Feasibility study of Li-Fe batterypacks for a 12v car system
MASTER-THESIS
MA 709
written by
Gernot Hehn
Institut fur Elektronikder Technischen Universitat Graz
Leiter: Univ.-Prof. Dipl.-Ing. Dr.techn. Pribyl Wolfgang
in cooperation with
AMS Ag
Evaluator: Ass.Prof. Dipl.-Ing. Dr.techn Winkler GunterSupervisor at AMS: Dipl.-Ing. Manfreg Brandl
Graz, September 2012
1
Contents
1 Car Batteries 71.1 Typical Car 12V Electric System . . . . . . . . . . . . . . . . . . . . . . 71.2 Standard Car Batteries (wet cell lead-acid) . . . . . . . . . . . . . . . . 71.3 AGM Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.4 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4.1 Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.4.2 Discharging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5 Problems with Today’s System . . . . . . . . . . . . . . . . . . . . . . . 11
2 Li-Batteries 122.1 LiFePo4 Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2 Comparison with Lead Acid Batteries . . . . . . . . . . . . . . . . . . . 122.3 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.1 Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.3.2 Discharging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.3.3 Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 LIN 183.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.2 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2.1 Break Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.2.2 Sync Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.2.3 PID Protected IDentifier Field . . . . . . . . . . . . . . . . . . . 203.2.4 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.2.5 Checksum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.2.6 Frame Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.2.7 LIN Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4 USB2LIN 234.1 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.2 Choice of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.3 Schematic & Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.4 Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.5 Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5 LiFe Battery Management 265.1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275.2 Choice of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275.3 Schematic & Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.4 LiFe Battery Management Firmware . . . . . . . . . . . . . . . . . . . . 30
6 PC-Software 36
7 Evaluation 397.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.1.1 Car Battery Setup . . . . . . . . . . . . . . . . . . . . . . . . . . 397.1.2 Lab Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
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Contents
7.2 Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427.3 Power Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457.4 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457.5 Safety Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467.6 Car Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8 Conclusion 54
9 APPENDIX 559.1 USB2LIN Schematic and Layout . . . . . . . . . . . . . . . . . . . . . . 559.2 LiFe Battery Management Schematic and Layout . . . . . . . . . . . . . 559.3 3D Drawing of the Retrofit Battery . . . . . . . . . . . . . . . . . . . . . 55
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Contents
EIDESSTATTLICHE ERKLARUNG
Ich erklare an Eides statt, dass ich die vorliegende Arbeit selbststandig verfasst, andereals die angegebenen Quellen/Hilfsmittel nicht benutzt und die den benutzten Quellenwortlich und inhaltlich entnommenen Stellen als solche kenntlich gemacht habe.
Graz, am September 20, 2012 . . . . . . . . . . . . . . . . . . . . .
(Unterschrift)
Englische Fassung:
STATUTORY DECLARATION
I declare that I have authored this thesis independently, that I have not used other than the
declared sources / resources and that I have explicitly marked all material which has been
quoted either literally or by content from the used sources.
September 20, 2012 . . . . . . . . . . . . . . . . . . . . . . . .
(signature)
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Abstract
Vehicle electronics have been hugely influenced by the enormous advantages that have beenmade in the fields of electronic and microelectronics. New appliances like climate controlvehicle safety systems (ABS/ESP/. . . ), modern route and navigation systems, on board en-tertainment and passenger comfort applications have increased the demand for power and en-ergy in cars dramatically. Adding to these new environmentally driven trends like start/stop,regenerative breaking, electrical power steering and mild hybrid solutions are increasing thedemand for energy even more. The load on a modern mid to high end limousine powersystem has reached levels that will wear out the battery in an unsatifactorily short time. Tar-geting these problems two solutions are presently discussed by the big German automotivecompanies. Either a higher voltage (preferrably 48V) board net is implemented, partiallysubstituting the classic 12V net, or the battery chemistry is changed towards a more robustand cycle resistant LiFePO4 system.
This thesis will evaluate the viability of the second solution. The goal is to enable under-standing of the differences in battery chemistry, why they help target today’s problems, andto explain necessary changes in the cars system to make the transistion. It will also propose abattery management system that performs all the necessary operations to keep the Lithiumbattery within its operating conditions. The last chapter will outline the practical evalua-tion of this system in a real world application and show how well the new system performscompared to a classic lead-acid battery system.
5
Zusammenfassung
Die Fahrzeugelektrik wurde enorm beeinflusst durch die Fortschritte in den Feldern Elek-tronik und Mikroelektronik. Neue Zusatzausstattungen wie Klimaanlage, Sicherheitssysteme(ABS/ESP/. . . ), moderne Navigationsgerate, integrierte Entertainment Systeme und Ap-plikationen fur den Fahrerkomfort haben die Energie und Leistungsanforderungen in Au-tos drastisch erhoht. Zusatzlich zu diesen Systemen haben auch durch Umweltbewusst-sein getriebene Trends wie start/stop Automatik, regeneratives Bremsen, elektrische Serv-olenkung und mild Hybrid Antriebe den Bedarf an elektrischer Leistung im Auto weiter indie Hohe geschraubt. Die elektrische Last in einem modernen Mittel- und Oberklassewagenhat einen Bereich erreicht in dem eine klassische Batterie in unzulanglicher Zeit ihre Funk-tion aufgibt. Um diese Probleme in den Griff zu bekommen werden derzeit zwei Losungenvon den deutschen Automobilkonzernen diskutiert. Entweder ein Bord Netz mit hohererSpannung (vorzugsweise 48V) wird implementiert das die Aufgaben des 12V Netzes zum Teilubernimmt, oder die Batteriechemie wird geandert, zu einer LiFePO4 Chemie mit wesentlichbesserer Zyklenfestigkeit und Hochstromeigenschaften. Diese Arbeit wird die Machbarkeitder zweiten Losung beleuchten. Ziel ist es das Verstandnis fur verschiedene Batteriechemienaufzubauen und zu zeigen warum mit diesen die heutigen Probleme gelost werden konnen.Auch die notigen Anderungen, die fur diese Umstellung am Auto selbst vorgenommen wer-den mussten, werden besprochen. Diese Losung wird anhand eines Batterie ManagementSystems, welches alle notwendigen Operationen beherrscht um eine Lithium Batterie inner-halb ihrer Operationsbedingungen zu betreiben, beleuchtet. Das letzte Kapitel wird sichmit der Evaluierung diese Systems in einem handelsublichen Fahrzeug auseinandersetzen unddabei einen Vergleich zu herkommlichen Losungen bieten.
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1 Car Batteries
1.1 Typical Car 12V Electric System
The typical electric system in today’s car would look somewhat like Figure 1.1 The alternator,which is directly coupled to the engine block, will supply a uniform 12V net. The battery willbe charged until it reaches a defined maximum voltage. A control unit within the alternatorwill regulate its exciting current so that the output voltage won’t surpass a level of 13.8 ≈14.4V . With the application of a Battery management system and the knowledge about theState of Charge (SOC) of the battery it has become possible to only charge the battery whennecessary or in desired conditions (regenerative breaking for example). This also allows to stopcharging the battery when the motor power is needed elsewhere (for example in accelerationphases).
Figure 1.1: Typical car battery system
1.2 Standard Car Batteries (wet cell lead-acid)
The car battery most commonly used today is a ”flooded cell” wet type lead-acid battery.The battery consists of 6 serially connected primary lead acid-cells with a typical voltage of2V each. A single cell typically consists of a negative electrode made of spongy or porouslead, the positive electrode made of lead oxide and an electrolyte made out of 35% SulfuricAcid and 65% water. Additionally there is a permeable separator separating the electrodes tostop them from accidentially connecting. As the name of the battery suggests both electrodesare submerged in the electrolyte. The chemical reaction that allows these batteries to workis as follows:
Overall reaction:
PbO2 + Pb + 2 H2SO4
discharge−−−−−−−−−−−−−−charge
2 PbSO4 + 2 H2O
At the negative terminal:
Pb + SO2−4
discharge−−−−−−−−−−−−−−charge
PbSO4 + 2 e−
7
1 Car Batteries
At the positive terminal:
PbO2 + SO2−4 + 4 H+ + 2 e−
discharge−−−−−−−−−−−−−−charge
PbSO4 + 2 H2O
1.3 AGM Batteries
AGM (Absorbed Glass Mat) batteries belong to the group of VRLA (Valve Regulated LeadAcid), ”sealed” or ”maintainance free” batteries. AGM batteries use a very fine fiber Boron-Silicate glass mat seperator to immobilize the sulfuric acid in the battery. This type of batterywas invented for military applications in the 80’s. The main advantages compared to a classiccar battery are
• Lower self discharge rate
• Higher number of charge cycles
• Less capacity degradation
• Safer than wet batteries
• Virtually maintainance free
• Can withstand hazardous environments better
Their main disadvantage is that they are more expansive (≈ 20−30%) compared to standardbatteries.
However car manufacturers tend to use these kind of batteries in modern cars featuringStart/Stop to get acceptable lifetimes.
1.4 Handling
Like all batteries lead-acid batteries have special requirements concerning their operation.These can be split into charging and discharging conditions.
1.4.1 Charging
As Figure 1.2 shows there are 4 distinct phases in the charging process
1. Bulk Charge or CC (Constant Current) mode:
In this mode the battery is somewhere between 30% and 80% SOC (discharge below30% SOC will damage the battery permanently) The charger applies a constant currentsomewhere between 1
10and 1
3of the battery’s capacity. The voltage climbs to a level
called the ”quick charging voltage”. This phase is where most charge is absorbed bythe battery in the shortest amount of time.
2. Absorbtion Charge or CV (Constant Voltage) mode:
In this mode the battery receives another 15% of charge. This phase is qualified bythe constant voltage applied to the battery. The current drawn by the battery slowlydecreases due to the chemical process in the battery coming close to equilibrium.
3. Equalization Charge Mode:
In this mode a modest constant current in the range of 5% to 10% is applied to pushthe battery to the gasing phase on purpose. This mode helps to deliver the remaining5% of capacity into the battery and to equalize the charge between the 6 cells in atypical system. This phase is typically not used in automotive application as gasing is
8
1 Car Batteries
Figure 1.2: Diagram of the 4 lead-acid battery charging phases [24]
highly undesired in a car (the gas consists of elementar Hydrogen and Oxygen and ishighly explosive).
4. Float Maintenance Charge Mode:
This mode is only used in charging systems for battery storage. Typically a very smallcurrent in the 50 to 100mA range is applied to compensate the battery’s self dischargeprocess. This mode is not implemented in a car system as there is no power sourceother than the battery to charge from during the time the car is parked.
1.4.2 Discharging
Like every chemical process the discharging process of a lead acid battery is dependent on thetemperature at which the reaction takes place, the concentration of the active partners in theelectrolyte and the rate of Ion transfer (ie. the amount of current drawn from the battery)
This leads to the discharge performance of a Lead-acid battery being significantly dependenton
• Discharge current relative to the total capacity of the Battery (C-rating)
• The percentage of capacity used during a cycle (aka. cycle depth)
• The temperature of the battery during discharge
This means that the amount of charge the battery is able to deliver as well as the number ofcycles the battery is able to endure is dependent on those parameters.
A dependence which is illustrated in Figure 1.3 through 1.5
9
1 Car Batteries
Figure 1.3: Influence of the discharge current on the usable capacity [5]
Figure 1.4: Influence of the discharge current on the usable capacity [4]
10
1 Car Batteries
Figure 1.5: Influence of the discharge current on the cycle life [5]
1.5 Problems with Today’s System
A classic car system typically used its battery only once per drive to start the motor andsupply power to lights etc. when the car was parked. In a modern car system the load onthe battery is mounting drastically due to the increased number of electrical appliances. Inaddition to that a start stop automatic makes it necessary to cycle the battery more thanonce during a drive cycle and use a higher percentage of its capacity. This leads to thebattery beeing constantly in a charge state somewhere around 50% SOC rather than beingfully charged most of the time as this was the classic case.
This leads to early battery failures in the field and the necessity to change batteries moreroutinely than it was the case before.
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2 Li-Batteries
”One of the important things to understand about lithium batteries is that the term ’LithiumBattery’ summarises a whole lot of different battery chemistries. In fact the technology inthis field is still changing, so I can’t even give a full overview of the existing technologies.”[23]
In this text I will focus on the LiFePo4 type of batteries and the differences in handlingcompared to lead acid batteries to point out the problems and advantages arising from thischange in battery chemistry.
2.1 LiFePo4 Batteries
To start off let us have a look at a LiFePo4 Cell and what it is made of.
This type of cell consists of a cathode made out of LiFePo4 material, an anode of graphite orhard carbon and a lithium ion conducting electrolyte, usually an organic solvent mixed witha lihium salt. The chemical reaction taking place in such a battery is as follows:
LiC6(s) + Fe3+PO4
discharge−−−−−−−−−−−−−−charge
6 Cs + Li+Fe2+PO4(s)
2.2 Comparison with Lead Acid Batteries
The table 2.1 gives a good overview of the difference in properties between lead acid batteriesand LiFePo4 batteries. I have added the LiCoO2 type of lithum batteries for comparison.This is the type used in most modern computers and cell phones. Although these cells have aneven higher energy density, they are not considered for automotive application since they arenot intrinsically safe and suffer from a process called thermal runaway. This process can leadto an explosive decomposition of the battery when overcharged, which has led to a lot of recallsof batteries where the protection mechanism wasn’t adequate [19] & [18]. Needless to saythat such an instable nature disqualifies these batteries for usage in automotive applications.
Summarized the main advantages of LiFe batteries are the following:
• ≈ 4 times higher cycle life
• ≈ 3 times the energy density which is shown in Figure 2.1
• Very flat voltage curve 2.2
• High charge rates
• Low self discharge
• Unlike lead acid batteries, can be left in a partially discharged state for extended periodswithout causing permanent damage
• Maintenance free for the life of the battery
• Can be operated in any orientation
• No heavy metals used
In contrast these new batteries also have the following disadvantages:
12
2 Li-Batteries
Figure 2.1: Comparison of energy density of various battery types [20]
Figure 2.2: Comparison of discharge curves of various battery types [7]
13
2 Li-Batteries
• ≈ 2 - 3 times the costs
• Problems with low temperatures
• More critical in over and undercharge conditions
Battery Type Lead Acid LiFe LiCoO2
Commercialisation 1881 2002 1990Cell Voltage [V] 2 3,2 3,7
Energy by Weight [Wh/Kg]: 30-40 90-110 130-200Specific Power [W/Kg] 180 300 250 - 340
Energy by Volume [Wh/L] 60-75 220 340-400Max charge rate 1C 3C 5C
Continous discharge rate 3C 3C-10C 10C-30CPeak discharge rate 10C 10C-30C 30C-70C
Recharge Time ≥ 10 Hours 1 Hour 15min - 1hourCycle Life [Cycles] 500 - 800 2000 - 3000 500-1000
Self Discharge per month 5%-25% ≈ 3% ≈ 5Temp Range [C] -15 to 40 0 to 45 0 to 45
Preferred Charge Method CC/CV CC/CV CC/CVAverage Energy Cost [$/kWh] $100 $300 $200
Size [%] 100 75 30Weight [%] 100 35 25
Table 2.1: Comparison of Lead Acid and Lithium cells
2.3 Handling
As discussed in the disadvantage section above, Lithium based batteries are very susceptibleto over- and underload conditions. This requires the usage of specialised electronics whichkeeps the batteries within their specified parameters under all conditions. We can summarizethe tasks such an electronic has to fulfill as:
• Measure the pack voltage
• Measure the individual cell voltages
• Do a plausability check of pack voltage versus sum of cell voltages
• Measure the current being charged into or discharged from the battery
• Measure the temperature of the battery stack
• Try to equalize the charge between the different cells of a stack
• Compare the measured values against the maximum ratings described by the batterymanufacturer
• If any of the values is out of spec, disconnect the battery immediately
• Try to estimate the amount of charge still available in the battery
• Report the battery status and the system status to the ECU (typically via a LINinterface)
2.3.1 Charging
The charging system used for Li-type batteries is the CC (Constant Current)/CV (ConstantVoltage) system. This is the same as the first two phases in a lead acid charging process.
14
2 Li-Batteries
The third phase may never be used due to the reaction of lithium batteries to overchargeconditions and the fourth phase is mostly unnecessary due to the low self discharge rate thatall lithium batteries have in common. A typical charging curve (taken form the datasheet[6]) is shown in Figure 2.3
Figure 2.3: Plot of charging operation
2.3.2 Discharging
As with lead acid batteries the discharging characteristics hugely depend on current consump-tion (Figure 2.4) and temperature (Figure 2.5) as well as aging effects and the SOC.
These effects have to be addressed by the battery management in order to allow safe operationof the battery in its final application.
2.3.3 Balancing
Balancing is the process we use to equalize the charge of individual cells within a batterypack. There are a couple of different topologies in use to achieve these goals. [23] gives agood overview of the various possibilities. In this work I will however concentrate on activebalancing using an inductive coupler to transport charge between various cells. As discussedin section 5.2 we are using an AS8505 chipset to enable this functionality. A block diagramof this chipset can be seen in Figure 2.6.
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2 Li-Batteries
Figure 2.4: Plot of discharging operation at various discharge rates
Figure 2.5: Plot of discharging operation at various temperatures
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2 Li-Batteries
Figure 2.6: Block diagram of the AS8505/06 chip including peripheral components
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3 LIN
3.1 Basics
‘LIN (Local Interconnect Network) is a concept for low cost automotive networks, whichcomplements the existing portfolio of automotive multiplex networks.’[21]
LIN is a single wire serial communication bus that was mainly developed for automotiveapplications which don’t require the complexity and speed of CAN and want to profit froma cost effective simple solution. The main benefits of the LIN architecture are:
• one master multiple slave network
• low cost implementation using standard uart (Universal Asynchronous Receiver Trans-mitter) hardware
• possibility to synchronize slaves that don’t have a stable clock source
• low cost single-wire implementation
• speed up to 20 kbit/s.
In the LIN Interface the master has control over all bus functions. It initializes transfersto and from the slaves and manages the bus activity schedule. The slave waits for its PID(Protected IDentifier) and responds with a pre defined answer.
Figure 3.1: Typical LIN network
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3 LIN
3.2 Protocol
Figure 3.2: LIN Frame
The LIN Protocol describes a LIN frame consisting of
• Break field
• Sync field
• PID
• 1-8 bytes of data
• Checksum
The first three items are considered to be the header and are always sent by the master. Thedata bytes and checksum are the slaves response to the master request. LIN protocol definesan LSB first bit order. We will now take a look at the function of each item
3.2.1 Break Field
The break field stands at the beginning of each LIN communication. It is essential to signalthe beginning of a new transmission and to wake up all devices connected to a LIN Bus (ifthey are in sleep mode). The break field shall be at least 13 nominal bit times of dominantvalue (low voltage) followed by a break delimiter as shown in Figure 3.3 The slave node shalluse a threshold of 11 slave bit times to detect the break field in order to allow for clockvariations.
Figure 3.3: LIN Break field
3.2.2 Sync Field
The Sync field always transmits the data value 0x55 and is used to calibrate the bit clock ofthe slave with the master. This is essential if the slave uses a cheap low accuracy rc oscillator.Modern microcontrollers have integrated hardware that auto detects the sync field and makesthe baud (data transfer rate) calibration easier.
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3 LIN
Figure 3.4: LIN Sync field
3.2.3 PID Protected IDentifier Field
The protected identifier consists of the frame identifier (Bits 0 to 5) and two parity bits (6and 7). ID Values 0 to 59 are used for signal carrying frames, 60 and 61 for diagnostic framesand configuration data 62 and 63 are reserved.
The Parity calculation works as follows:
P0 = ID0⊕ ID1⊕ ID2⊕ ID4
P1 = ¬(ID1⊕ ID3⊕ ID4⊕ ID5)
The mapping of the PID frame is shown in Figure 3.5
Figure 3.5: LIN PID field
3.2.4 Data
The Data frame carries between 1 and 8 bytes of data. Data is always transported LSB first.This also applies to data fields that span over multiple bytes. The LSB is always transmittedin the byte that is sent first.
3.2.5 Checksum
The last Field of a LIN transmission is always a Checksum. According to the new LIN2.2 specification, the Checksum is calculated over the data bytes as well as the PID. Thechecksum is an inverted eight bit sum with carry. For example if we transmit the followinginformation: PID=20 Data1 = 80 Data2 = 200 Data3 = 14 we would get
20 + 80 + 200 + 14 = 314− 255 = 59
¬59 = 196
So the checksum would be 196. The receiver checks this by adding the PID and Data fieldsand the Checksum. The result should always be 0xFF.
3.2.6 Frame Types
The LIN protocol distinguishes between three types of frames
• Unconditional Frame
• Event triggered Frame
• Sporadic Frame
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3 LIN
Unconditional Frames are in the PID range between 0 and 59. The header is transmittedby the master in the allocated time slot. The response of the slave shall be immediate. Allsubscribers to this frame will receive it and make it available to their application.
Event triggered Frames are used to request data from slaves only in case the data has changed.Subscribers to this frame only respond if the requested value has changed since the lastrequest.
In addition to these frames, Diagnostic Frames (with PID 60 and 61) carry a special transportlayer and are used for in-system diagnosis and calibration.
3.2.7 LIN Schedule
The master has knowledge about all PIDs used in this particular network. It uses a prede-fined schedule table to request data from the slaves and makes these data available to theapplication. The default flowchart for such a schedule looks like this:
Figure 3.6: LIN Master Task [21]p.41
For our purpose we did not implement a schedule table into our LIN master as can be seenin the software flowchart 4.1 and rather let the application running on the PC decide whenand which PID is going to be sent. This makes the overall software design easier and allowsfor more flexibility during testing, furthermore we do not need scheduling since there is onlyone LIN slave in this particular network.
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3 LIN
The LIN slave on the other hand has to follow a procedure shown in Figure 3.7
Figure 3.7: LIN Slave Task [21]p.43
The implementation of this behavior is discussed in detail in the Firmware section 5.4.
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4 USB2LIN
In order to test the functionality of the whole platform in general and the LIN system indetail and to create a user friendly way to access the module data on a computer a smallUSB to LIN interface was developed.
4.1 Operation
This system uses the power of a modern PIC 18f14K50 microcontroller to implement a fullyUSB compatible PC Interface that is represented as a virtual COM PORT on PC side andthe AS8530 LIN SBC to provide a standard compatible LIN interface.
In Figure 9.1 you can see that this chip is powered by an AS1340 DC/DC converter whichprovides the 12V supply necessary for correct LIN operation. The switch S2 allows forsystem reset as well as for the possibility to update the firmware via an integrates USB HIDbootloader. For system diagnosis two LEDs are placed which display the status of the board(connected/driver installed/operational).
4.2 Choice of Components
Microcontroller: The PIC 18F14K50 was chosen for its integrated hardware USB slave func-tionality and LIN Interface. Good application support for both these Interfaces is also pro-vided by Microchip.
Lin System Basis Chip: The AS8530 is a house internal LIN SBC. It provides the necessarylevel translations for the 12V LIN interface as well as load dump and ESD protection. It alsoallows for remote wakeup via LIN.
Dc/Dc: The AS1340 high efficiency DC/DC converter uses an internal 1.4A MOSFET toreduce the external part count and makes the small board layout possible.
4.3 Schematic & Layout
Schematic 9.1 and Layout9.2 can be studied in the Appendix section of this document. P1is a connector to the TTL compatible UART/LIN Interface of the microcontroller, whichallows easy observation of the LIN Bus through a logic analyzer. P2 is the connector to theLIN Interface. It also outputs the 12V power rail which can supply up to 200mA of powerto a slave application. Remember however that there is no short circuit protection, so theUSB port of your computer might get damaged in an overload condition. J3 is a PicKitcompatible header to allow direct programming and debugging of the PIC controller. If thePic programmer is used to upload firmware directly, you will however lose the Bootloaderfunctionality. It is worth noting that the LIN interface is ESD protected by the internal ESDprotection of the AS8530 chip, however the USB interface does not sport any ESD protectionother than that of the microcontroller itself.
Additionally I want to give a short connector pin listing starting from left to right with theUSB connector facing to the left side and the populated side of the board facing upwards.
PGC|PGD|GND|VCC|MCLR RX|GND|TX GND|LIN|12V
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4 USB2LIN
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via
vir
tual
co
m p
ort
PID
: 0x2
3B
AL
_ST
AT
(1B
yte)
[CE
LL
1 | C
EL
L2
| C
EL
L3
| CE
LL
4]
0 -
> C
ell i
s lo
wer
th
an r
efer
ence
1 ->
Cel
l is
hig
her
th
an r
efer
ence
ST
AT
US
(1B
yte)
[ER
RO
R |
RE
LA
IS |
OP
-MO
DE
| C
AL
IBR
AT
ED
]
PID
: 0x2
0C
UR
RE
NT
[mA
] (3
Byt
e)
VO
LT
AG
E [
mV
] (2
Byt
e)T
emp
erat
ure
[°C
/10
] (2
Byt
e)
PID
: 0x2
2C
ell 1
[m
V]
(2B
yte)
Cel
l 2 [
mV
] (2
Byt
e)C
ell 3
[m
V]
(2B
yte)
Cel
l 4 [
mV
] (2
Byt
e)
PID
: 0x2
1C
har
ge
[uA
h]
(4B
yte)
Imp
edan
ce [
mO
hm
] (4
Byt
e)
Dep
end
ing
on
th
e se
con
d c
om
man
d
char
acte
r se
nd
Co
mm
and
PID
in t
he
ran
ge
of
0x1
0 t
o 0
x1F
Ch
eck
if s
lave
an
swer
s w
ith
co
rrec
t ch
ecks
um
Ret
ry u
p t
o t
hre
e ti
mes
Rep
ort
co
mm
and
O
K
PID
: 0x1
#
US
B u
np
lug
ged
Rep
ort
err
or
Aft
er 3
rd t
ime
Figure 4.1: USB2LIN Software Flowchart
24
4 USB2LIN
As one can see in Figure 4.1 the software flow of the USB2LIN Interface is based arounda virtual serial port presented to the PC side. This port allows connection with any soft-ware capable of serial communication with communication settings 115200kBaud 8N1. Afterconnection to a USB port the USB2LIN Firmware awaits the entry of a human readablecommand. The Firmware will accept either a ”p” [ASCII: 0x70] data package query followedby a hex number between 0 and F and upon reception it will start to request the informationassociated with this PID or and ”s” [ASCII: 0x73] followed by a hex number between 0 andF which will prompt it to send the according Command PID in the range of 0x10 to 0x1F.Upon reception of the slave answer it will check the data for integrity with the help of theLIN checksum and report it back to the PC via the virtual serial interface as human readableASCII data. In case of an error the Interface will try to resend the command up to threetimes. If this doesn’t work, it will report an error to the host with the string ”er”.
4.5 Bootloader
The PIC18 Microcontroller is programmed with the microchip HID-Bootloader available aspart of the Microchip Application Libraries[22] After installation of this package the nec-essary software can be found under ”Microchip Solutions v2012-12-05\USB\Device - Boot-loaders\HID \HIDBootloader (Windows).exe” This program will allow you to upload newfirmware to the microcontroller in use via the USB connection and an easy to use graphicalinterface.
To upload new firmware perform the following steps:
1. Start the HIDBootloader according to your operating system
2. Press the button on the USB2LIN board
3. While pressing the button connect the board to the USB interface of the Computer
4. The Bootloader software will recognize the attached board and display ”Device at-tached”
5. Click the ”Open Hex File” button and select the new firmware file
6. Click the ”Program/Verify” button. This will program the new firmware
7. After successful flash operation (as in Figure 4.2) disconnect the board from USB andthen reconnect it
8. The new Firmware should now be in operation
Figure 4.2: HID Bootlader after successful flashing operation
25
5 LiFe Battery Management
As was discussed in the section about Battery technologies the usage of lithium based batteriesnecessitates the installation of a battery management system. In the following chapter I willintroduce a concept for a system that provides all the features required to safely operate aLiFePo4 Battery in a car environment.
The main design concerns for such a system were:
• Accuracy
The system has to achieve an accuracy of <10mV and <100mA over the whole auto-motive temperature (-40 - +125C) range and the complete voltage and current rangeof the batteries
• System Safety
The system has to be able to detect malfunctions and react to them accordingly.
• Processing Power
For the implementation of a complex battery model, which is essential for good SOC/SOHestimation, a fast processor is required to compute the mathematical model within anacceptable time frame
• Power consumption
The targeted power consumption in standby mode was 100µA for the whole system.
26
5 LiFe Battery Management
5.1 Block Diagram
The Block diagram (Figure 5.1) gives a good overview of the interaction of the differentfunctional blocks in use. The batteries are connected to the AS8515 ADC chip as well asthe AS8506 balancing chip. These two ICs supply most of the functionality required in thissystem. A battery disconnect switch and a 100 µΩ Shunt are connected in series with thepower path of the battery, which is available at two pole plugs on the top of the case likein a classic lead acid battery. USB and JTAG connectivity have been implemented to makethe debugging process easier. However the production version would obviously only have theLIN connection to communicate with the ECU.
5.2 Choice of Components
Microcontroller:Since the trend in Battery Management Solutions points towards ever more complex math-ematical models for the battery chemistry and behavior, the major decision factor for themicrocontroller used was to supply enough power for such a model in a small affordable pack-age. The ARM Cortex M Series of microcontrollers is gaining widespread acceptance in thedeveloper community due to the possibility of choosing from a number of different develop-ment and debugging tools and the possibility to change chip manufacturers whilst staying inthe same architecture. The microcontroller of our choice is the Fujitsu MB9AF312K[9]. Itbelongs to the FM3 Series of Fujitsu microcontrollers which are based on the ARM Cortex-M3architecture and sport a wide variety of peripheral units. With 128Kbyte of Flash storagefor program data and 32Kbyte of Work Flash, a maximum operating Frequency of 40MHz,a number of peripheral functions including LIN,USB and multiple SPI interfaces in a small48pin LQFP package, it is well equipped to serve as the processing unit in this device.
Data acquisition + System Basis Chip:To measure total current, four cell voltages, total pack voltage and temperature the systemis using the AS8515 IC[3]. This chip provides two independent ADC channels with pro-grammable gain amplifiers to support a wide measurement range. Measurement of batteryvoltage is supported through resistive attenuator with disable function for power saving instandby. After analog to digital conversion and digital filtering, the resulting digital valuesare accessible through 4-wire serial interface. The device is powered directly from the batterythrough an integrated linear regulator and provides a 3.3V supply for the microcontroller.Additionally the IC integrates a LIN 2.1 transceiver which is used as the main communicationinterface in this application.
Active Balancer:The balance portion of the circuit is handled by the AS8506[2] active balancing IC. This chipssupports balancing up to 7 cells via integrated transmission gates and an external flybacktransformer which is commutated via the chip. The balancing decision is made by simulta-neous comparison of all cell voltages against an internal or external reference voltage. Cellswhich are below reference/average will receive charge packages from the external transformer.Communication with the microcontroller is handled via a 4 wire serial interface as well as theBalance done, Cell Voltage NOK, Wake and Trigger signals.
Voltage Level TranslatorTo translate the logic signals between the 5V domain used by the active balancing circuit andthe 3.3V domain used by the rest of the circuit a ”TI TXB0108 8-BIT BIDIRECTIONALVOLTAGE-LEVEL TRANSLATOR WITH AUTO-DIRECTION SENSING AND ±15− kVESD PROTECTION”[13] chip was used. The auto direction sensing feature comes in handysince we need to translate signals in both directions and didn’t want to use two chips. Addi-tionally the chip features a very low power consumption of just 4µA
Flyback TransformerIn order to operate the active balancing we need a flyback transformer that translates the
27
5 LiFe Battery Management
AS
851
5A
DC
4 t
o 1
M
UX
10
0 μΩ
Sh
un
t
Sen
se C
ell
32-b
itF
ujit
su-F
M3
Mic
roco
ntr
olle
r
AS
850
6A
ctiv
e-B
alan
cin
g-I
C
3,3V
/ 5V
Lev
el S
hif
ter
SPI + lin
SPI + Status signals
Sen
se V
bat
BatteryDisconnect
Switch
Su
pp
ly O
ut
Su
pp
ly V
bat
3,3V
3,3V
SP
I + S
tatu
s si
gn
als
5VV
ref
in
Fly
bac
k C
on
vert
er
Figure 5.1: Battery Management Hardware Block Diagram
28
5 LiFe Battery Management
≈ 12.8V pack voltage to a single cell voltage between 2.0V − 3.8V . The typical output cur-rent should be in the range of 100mA. So we can start with the following design considerations:
Uin/nom = 12.8V Uout = 3.8V Iout = 0.1A f = 100kHz wr(windingratio) = 1 duty = 25%
The minimum required inductance required for continuous mode operation is given by theformula:
L =T ∗ wr2 ∗ U2
in ∗ Uout
2 ∗ Iag ∗ (Uout + wr ∗ Uin)2
where Iag is given by
Iag =∆I
2∗ toff
T= frac0.12 ∗ 0.75 = 0.0375A
With this information we can calculate the required inductance to be at least
L =1E − 5 ∗ 1 ∗ 12.82 ∗ 3.8
2 ∗ 0.0375 ∗ (3.8 + 1 ∗ 12.8)2= 83.42µH
For our tests we used a Wuerth WE-FLEX[16] 749196111 type transformer. This transformerhas 6 individual windings that can be connected in parallel or series. Our configuration uses3 windings in series for both primary and secondary side, giving as a 1:1 winding ratio andan inductance of 246µH. Since this is about triple the inductance necessary for continuousoperation we decrease the current ripple to
Iag =T ∗ wr2 ∗ U2
in ∗ Uout
2 ∗ L ∗ (Uout + wr ∗ Uin)2= 0.0136A
and a typical current ripple of
∆I =2 ∗ Iag ∗ ttoff
= 0.036A
In the real application however we had to increase the duty cycle to 35 to 40% to achieve the100mA continous charge output into the battery, as can be seen in Figure 5.2
Figure 5.2: Secondary current of the flyback transformer
29
5 LiFe Battery Management
ESD ProtectionESD protection was added to the USB port to protect from problematic discharges in theenvironment of a car whilst driving. The protection device of choice was a ST USBLC6-2[15]. It offers a two data line protection with very low capacitance and is available in a tinySOT23-6L package.
5.3 Schematic & Layout
Schematic 9.1 and Layout 9.2 can be studied in the Appendix section of this document. Atthis point I want to emphasize the crucial ideas that influenced this design and what impactthey have on system performance.The board is split into two sections. On the right hand side you can see the balancingsubsection comprised of the AS8506, the flyback transformer and a few necessary passivecomponents. On the left hand side we have the AS8515 placed directly overhead the currentmeasurement, alongside the Fujitsu microcontroller and close to the 5pin battery connection,the multiplexer. The reason for this split was to make these parts easily discernible as theboard will be used for demonstration purposes at ams. For low offset measurements thisdesign has to observe the following rules for the AS8515:
• The placement of the AS8515 should be as close as possible to the shunt (for a goodthermal coupling and to keep the traces as short as possible)
• The traces leading to the shunt may not be coupled to the ground plane, instead theyshould be connected to the center point of the shunt solder connection only
• The voltage sense pin and the supply pin shall be routed separately to the point wherepower is supplied to the board, so as not to introduce voltage drop on the sense linedue to the current being consumed
• The current shunt has to be soldered directly to the board using 2 3x12mm solder pads
For the 4 channel mux we used a common centroid layout and high precision resistors to builda divider that barely is affected by temperature deviation.
Furthermore the board uses a 4 layer PCB with one Ground and one Power Plane inside soas to reduce EMI.
The top portion of the board features a lot of communication ports. From left to right andtop-down we have connections for LIN (P1 LIN,GND), USB, UART(J11 3.3V-Level GND,RX, TX), serial-programming (J13 MD0, VCC), the connection for the battery disconnectswitch (J15 SW1, GND, SW2), the single supply (J2 VSUP, GND), the battery connector(J1, BAT4, BAT3, BAT3, BAT1, GND) and the dcdc connector (J5 DCDC, VSUP). Thebottom portion features a standard JTAG connector using the pinout described in [1]. Theconnection for the shunt is battery at the top and load at the bottom.
At last we included an LED (D10) to indicate the operation state of the board.
5.4 LiFe Battery Management Firmware
The Software was written in KEIL µVision4 [12] in ANSI-C and debugged using a SEGGERj-link [8] JTAG adapter. The block diagrams (Figure 5.3 & 5.4) give an overview of thesoftware operation.
The flow starts when the battery is attached to the board. The board initializes the twomeasurement systems and tries to load the calibration data from the work flash area of thechip. If that fails, default calibration values are used. After calibration an initial measurementis performed to check if the battery is operating within its SOA (safe operating area). In caseof a success the battery is connected to the load by activating the battery disconnect switchand the board goes on doing continuous measurements. At the end of each measurement itwill detect if any of the individual cells has drifted away from the average cell voltage and in
30
5 LiFe Battery Management
that case activates the balancing feature. The board will keep on measuring for 5 seconds andenter the standby mode if no communication is received. If however the board receives a LINrequest, it will handle this request and reset the timeout timer. So in order to keep the systemin measurement mode regular LIN requests have to be broadcast to the board (which accordsto the LIN Standard). If at any point a measurement is taken which doesn’t comply withthe SOA of the battery, the battery is immediately disconnected using the battery disconnectswitch, and the board enters a reset state in which it will respond to status requests butwon’t allow any other activity. Only a full reset, which can be done via a LIN command orby disconnecting the battery, will bring the system back to normal operation.
The available LIN requests can be seen in the block diagram (Figure 5.4). Lin communicationis handled by an interrupt service routine which evaluates the checksum of the broadcast LINmessage and makes the transported data available to the main program.
Communication to the AS8515 is handled by an interrupt service routine described in Figure5.5 triggered by the new measurement available interrupt of this chip. This ISR will activatethe switches in the mux to measure the individual cell voltages, besides pack voltage andtemperature, and discard each first measurement after the mux is changed in order to isolatethe measurement results from parasitic switching effects.
After being triggered the AS8505/06 chip autonomously handles the whole balancing process.This process is done in three phases:
1. Wait for trigger: In this phase the Chip waits for a trigger signal to begin the balancingprocess:
2. Compare phase: In the compare phase AS8505 detects number of cells connected to thedevice. The connected cell voltages are then compared with upper & lower thresholdsand cell target voltage of all cells connected.
3. Balance phase: The balance phase is basically charging cycle in case of active balancingand discharging cycle in case of passive balancing. The balance phase is divided intoseven time slots. The device will move through all seven time slots irrespective ofnumber of cells connected to the device. One time slot is assigned to each cell (sequentialorder) for charging or discharging. In each timeslot the the CVT NOK flag and theresult of the compare phase is checked for the according cell. If the cell is marked forcharging, the corresponding transmission gates are switched on and a PWM signal issent to the flyback converter. At the end of the current time slot the PWM is turnedoff the switches are disconnected and the device moves to the next timeslot.
This is also explained in Figure 5.6
Functional Safety is provided by:
• Comparison of the individual cell voltage measurements against the pack voltage mea-surement to detect problems with the mux
• Shunt connection breaks are detected by applying a small current from the internalcurrent source
• Measurement of the Interrupt Timing of the AS8515 to determine correct operation
• A hardware watchdog is implemented in the Fujitsu controller to detect softwarehangups
31
5 LiFe Battery Management
Power On
Initial Measurement
LIN timeout?
Wait For measurement_completed
Flag
NO
Maximum Parameter Check
AS8505 CVT_NOK
Standby active?
Everything OK
Wait for AS8510 Interrupt
Go into Standby Mode / Set AS8515 into Standby Mode
MCU Wakeup/AS8515 Setup
YES
YES
InitialisationRead Calibration Values
Activate Power Relais
Maximum Parameter Check
Everything OK
Save Error
Deactivate Power Relais
Parameters not OK
Wait for Host reset
Command received
Execute command
YES
NO
Cell Misbalance Check
Start cell balancing (Trigger AS8505) Misbalance
NO
Stop Balance
Stop cell balancing
No MisbalanceBut AS8505 still active
Figure 5.3: LiFe Management Main Block Diagram
32
5 LiFe Battery Management
LIN
Inte
rru
pt
Wak
eup
if w
e ar
e in
S
tan
db
y M
od
e
Is t
his
a c
om
man
d o
r a
dat
a re
qu
est
Co
mm
and
PID
bet
wee
n 0
x10
an
d 0
x1F
Sen
d d
ata
pac
kag
e vi
a L
IN
En
d o
f In
terr
up
t
Req
ues
t: P
ID 0
x20
-0
x30
BA
L_S
TA
T (
1Byt
e)[C
EL
L1
| CE
LL
2 |
CE
LL
3 | C
EL
L4
]0
->
Cel
l is
low
er t
han
ref
eren
ce1
-> C
ell i
s h
igh
er t
han
ref
eren
ce
ST
AT
US
(1B
yte)
[ER
RO
R |
RE
LA
IS |
OP
-MO
DE
| C
AL
IBR
AT
ED
]
PID
?
CU
RR
EN
T[m
A]
(3B
yte)
V
OL
TA
GE
[m
V]
(2B
yte)
Tem
per
atu
re [
°C/1
0]
(2B
yte)
BR
EA
K|S
YN
C
CH
EC
KS
UM
PID
0x2
0
Cel
l 1 [
mV
] (2
Byt
e)C
ell 2
[m
V]
(2B
yte)
Cel
l 3 [
mV
] (2
Byt
e)C
ell 4
[m
V]
(2B
yte)
PID
0x2
2
PID
0x2
3
Ch
arg
e [u
Ah
] (4
Byt
e)Im
ped
ance
[m
Oh
m]
(2B
yte)
PID
0x2
1
PID
: C
om
man
d0
x10
: C
alib
rate
Bas
e0
x11
: Act
ivat
e P
ow
er S
wit
ch0
x12
: C
alib
rate
Cel
ls0
x13
: Sta
nd
by
0x1
4 :
Pri
nt
Cal
ibra
tio
n0
x15
: Pri
nt
Mea
sure
men
t0
x16
: C
alib
rati
on
Era
se0
x17
: Cal
ibra
tio
n T
est
0x1
8 :
850
5 S
tart
0x1
9 :
850
5 S
top
Exe
cute
Co
mm
and
in
mai
n p
rog
ram
Figure 5.4: LiFe Management LIN Block Diagram
33
5 LiFe Battery Management
Figure 5.5: LiFe Management AS8515 Interrupt Block Diagram
34
5 LiFe Battery Management
Figure 5.6: AS8505 state diagram
35
6 PC-Software
The PC Software was developed in C# using Microsoft Visual Studio Express [11] and runson Microsoft Windows XP and upwards. It requires the .NET Framework 4, which canbe downloaded from [10] and the Microchip CDC driver (which is part of the MicrochipApplication Library [22] Subfolder /USB/Device - CDC - Basic Demo/inf) for the USB2LINBoard. The software utilizes the excellent ZedGraph library [17] for all plotting functions. Itwas developed to display data from the battery management board which it requests via LINinterface using the USB2LIN converter board. A Screenshot of the Software can be seen inFigure 6.1
Figure 6.1: PC-Software screenshot
The Software Screen is partitioned in 3 parts.The top part is used for connecting to the USB2LIN interface.The Software will automatically enumerate all USB serial devices and display the associatedCOM port number as well as the Hardware Identifier in the drop down menu at the top of thesoftware, which makes it easy for the user to recognize the correct device without looking itup in the Windows Hardware Manager. The button to the left is to restart the enumerationprocess if new devices have been plugged in since the program start. The buttons to the rightallow connecting and disconnecting the device. A status field will show if the connectionsucceeded.A tab handler provides access to different portions of this software.
As the software was developed for a few different demonstration boards, we will only usethe Life and the calibration tab.The Life tab consists of:
• The button portion
Save: To save all raw data into a .csv file
36
6 PC-Software
Read volt \ current: to make a single read of pack voltage and current
Read cells: to make a single cell voltage reading
Read continuous: to start continuous reading and plotting of all values (updaterate 10Hz)
Pause: to pause the continuous reading
Clear: to clear all display fields
• A Label showing the integrated charge sum in [mAh]
• The left hand side which will display the raw data read back from the Life-BatteryManagement Board.
Values are from left to right
Current[mA]
Voltage[mV]
Charge Integration Sum[µAh]
Impedance [mΩ]
Cell Voltages 1 to 4 [mV]
AS8505 Balance Register
System status byte
Bit 1 Balance is done
Bit 2 Cell voltages are not ok
Bit 3 Balancing active
• The upper graphics will display instantaneous current [mA] and pack voltage [mV]
• The lower graphics will display instantaneous cell voltages [mV] of each individual cell.
• The middle part visualizes the data from the balancing IC. It shows which cells areselected for balancing, and which, if any, are over or under their specified voltage range.
Figure 6.2: PC-Software calibration tab
37
6 PC-Software
The Calib tab shown in Figure 6.2 consists of:
• Input fields for the Cell voltages [V]
• Button Calib Cells: to activate the calibration. Keep in mind that a measurement willbe taken and the raw data compared to the values you input in the fields, and then acalibration set is stored on the microcontroller
• Input fields for the pack voltage [V] Current [A] and Temperature[C]
• Button Calib Base: same as Calib cells but here the calibration for the whole pack andthe temperature is performed
• Button Calib Erase: All calibration data will be erased from the microcontroller
The whole software is available as an installer package, which will not only install the softwarebut also the driver into a specified directory. When Windows asks for a driver for the newdevice, just point it to the install directory driver sub folder.
38
7 Evaluation
7.1 Setup
To evaluate our Battery Management System we created two evaluation platforms:
7.1.1 Car Battery Setup
As a real world application we constructed a 12V car battery replacement consisting of 440Ah LiFePo4 Prismatic cells made by HiPower [6], out battery management electronics anda battery disconnect switch from Tyco electronics [14] encased in a construction of PMMA(acrylic glass). The rendering in Figure 7.1 shows the layout of the 4 individual cells. A plasticintermediate floor seperates the batteries from the electronics. The top has two terminalposts, similar to common lead acid batteries, to make replacement as easy as possible. A LINconnector is accessible from the top via an RJ12 connector.
Figure 7.1: Rendering of the Battery Assembly
The batteries performance data taken from the datasheet are listed in Table 7.1
This battery was integrated in a Citroen C5 shown in Figure 7.2 & 7.3
7.1.2 Lab Setup
Furthermore we used a small 4cell LiFePO4 Battery Pack (Figure7.4) with 4Ah capacityfor lab evaluation and to test the functionality of the battery management as well as thebalancing.
39
7 Evaluation
Nominal Voltage 3.2VMaximum continuous discharge current 120AMaximum peak discharge current 400AMaximum charge current 120AVolumetric energy density 142.7Wh/lGravimetric energy density 95.5Wh/kg
Table 7.1: LiFe Battery Performance Data
Figure 7.2: Citroen C5 with replacement battery installed
40
7 Evaluation
Figure 7.3: Citroen C5 replacement battery closeup
Figure 7.4: 4Cell LiFePo4 Pack from TopFuel
41
7 Evaluation
7.2 Balancing
To evaluate the balancing function, determine its functionality and to estimate what dutycycle would bring the best balance between time efficiency and self heating of the chip we dida couple of lab measurements with the small 4cell LiFePO4 battery.
First we compared internal and external supply for the balancing process. The difference canbe seen in Figures 7.5 & 7.6
Figure 7.5: Balancing with external supply
Figure 7.6: Balancing with internal supply
The reason why the balancing with external source isn’t charging the battery as much aswould be expected lies in the energy consumption of the board. Let us look at an example.We assume that only one of the cells is below the balancing threshold and therefore willget charged by the balancer IC. From that we can calculate that the average current beingcharged into the battery is:
100mA
7cycles= 14, 2mA average charging current
The power consumption of the whole board in active state is roughly 12mA leaving only≈ 2mA as active charging current.
42
7 Evaluation
During testing of the balancing features we also stumbled upon a chip internal latch upbehavior which can be observed in Figure 7.7.
Figure 7.7: Balancing failure
The condition that triggers this behavior is when the current flowing into the lowest mostcell exceeds a value of ≈ 100mA.
Figure 7.8: Schematic of the portion of the AS8505/06 responsible for the problem
With high charging currents from the secondary voltage drop across R1 can be about 0.78Vto 1.5V. As the CGND is connected to ground and TSECL is floating, TSECL can go to-0,78V to -1.5V. This will trigger the ESD protection diode on the TSECL. Current will passthrough the D cond and can trigger the latch-up as the current is in the order of 130mA anda peak current of 300mA.
Two solutions for this problem seem viable:
• Put a 4.3V zener diode between TSECL and TSECH, which limits the over voltage butis wasteful. If the cells are fully discharged, then this may not work
• Decrease the PWM duty cycle to a value where this effect is not triggered.
A comparison of both variants can be seen in Figures 7.9 & 7.10
Judging from these graphs it seems that the added diode consumes a lot of the balancingpower. Therefore it makes more sense to use lower balancing currents than to introduce this
43
7 Evaluation
Figure 7.9: Balancing with Zener Diode
Figure 7.10: Balancing with lower current
44
7 Evaluation
wasteful diode.
7.3 Power Consumption
Power consumption was evaluated for the four operation states the board can enter. Allmeasurements were done using the Agilent 34401A Digital Multimeter.
Measurement + Balancer active: In this state all electrical systems are active. The typicalpower consumption here is ≈ 18mA
Measurement active: In this mode the balancer is in sleep mode whereas the microcontrollerand the AS8515 remain active. Power consumption in this mode is ≈ 10mA
Measurement standby + Balancer woken We run into this mode when the system is in sleepmode but wakes up to perform a balancer check. For this operation the AS8505/06 is wokenvia the WAKE pin and remains active for 1.2sec Power consumption in this mode is ≈ 9mA
Full standby: In this mode the microcontroller enters STOP Mode, the AS8515 is in StandbyMode 1 and the AS8505/06 is also in standby. Current consumption in this mode is ≈ 1mA,which is quite a lot for full standby. The reason for this lies in a few shortcomings of thishardware version as follow:
1. The resistive voltage divider for the reference of AS8505/06 is always connected drawingabout 300µA of current. This will be solved by the next chip sample version which hasan internal disconnect transistor to power down the voltage divider.
2. The AS8515 Standby Mode is not working correctly due to a bug in the recognition ofthe EN pin signal leading to another 300µA of current consumption. This bug is alsoknown and will be corrected in the final chip version.
The total power consumption can be split in the following sections:
Table 7.2: LiFe Management Power Consumption
Device Estimated Power Consumption Measured Power consumptionAS8515 5 5
MB9AF312K 3,9 4AS8505/06 10 9
As can be seen from Table 7.2 the estimated power consumption matches the realized powerconsumption pretty well. A total power consumption of below 20mA is very much acceptablefor a system such as this. The standby power consumption however should be reduced downto ≈ 100µA. An issue that will be resolved by the final version of the respective chip sets.
7.4 Accuracy
Accuracy measurements were done using an Agilent E3631A 80W Triple Output Power Sup-ply, an Agilent 34401A Digital Multimeter and a TTi CPX400A PSU. We tested linearityof all four individual cell voltage measurements as well as common mode dependency of theindividual voltage measurements. In addition we also tested the full voltage and currentchannel for accuracy.
In the first test (shown in Figure 7.11) we sweeped each of the individual cell voltages in 0.1Vincrements and measured all cell voltages. As can be seen the voltage sweep doesn’t influenceany of the other cell voltage readings. Also the measured voltage remains accurate down to0.5V (observable in Figure 7.12) at which point we start making a measurement error, which
45
7 Evaluation
is irrelevant, because the cell voltages won’t ever reach such a level unless they have longpassed their Safe Operating Area.
The second test was to show how well the system performs if the voltages are varying quickly.For this test we ramped the single voltages in 1V increments and observed all the measuredcell voltages. We can observe that the voltage jumps in one cell can lead to a wrong readingin another cell. The reason for this is the way the individual cell voltages are obtained. Weare using a multiplexer to measure the individual tabs of the cell stack. The cell voltagesare obtained by subtracting these values from each other. Because these values can notbe obtained simultaneously (because we are only using one ADC channel) it can happenthat one of the cell values is already updated to the new stack voltage while the other isnot, resulting in a faulty calculation of cell voltage. This can be seen in Figure 7.13. Tocircumvent this one could use multiple synchronous ADCs or a sample and hold circuit foreach voltage. Both solutions are costly, require more board space and are not required in thepractical application since the single cell voltages can’t be properly read during operation ofthe alternator anyway. It is however important that the total pack voltage measurement andthe current measurement are synchronized, so that we may calculate internal resistance ofthe battery pack or use a model to correctly estimate the battery’s SOC.
The last test was to show total pack measurement accuracy for current and voltage. Thistest was performed by stepping the voltage from 5V to 18V in 0.1V increments and thecurrent from 1A to 40A. Measurement accuracy is limited by the accuracy of the suppliesin use, which is 0.05% + 20 mV for the Voltage supply and 0.3% ± 2digit(20mA) for thecurrent source and the remaining output ripple, which is ≤ 350V rms/2mV pp for the voltagesupply. The voltage channel was however corrected by the usage of the Agilent Multimeterwith an accuracy of 0,0020% of the measurement value + 0,0006% of the range value givingan uncertainty of
0.002 ∗ 0.01 ∗ 12 + 0.0006 ∗ 0.01 ∗ 100 = 0.84mV
The conclusion we can draw from these measurements is that the accuracy of the measurementsystem is within the uncertainty of the supply. Overall accuracy can be established to bebetter than 2mV of 0.04% for the full voltage measurement and better than 80mA or 0.5%for the current measurement.
7.5 Safety Shutdown
The autonomous shutdown in case the battery SOA was breached turned out to be toounforgiving to allow normal operation in a car (as can be seen in Figure 7.16). The loadduring ignition triggered the safety shutdown more often than not.In order to allow normaloperation in a car while still being able to safely disconnect the battery in case of an error ashutdown counter was integrated in the battery management. With each measurement cycleif one of the SOA criteria is violated this count is incremented, each cycle if it is not thecase it will be decremented (down to 0). If the counter reaches a critical level, a shutdown isinitiated. The value of the counter was chosen so that the extreme conditions during ignitionwould be tolerated for ≈ 4seconds.
7.6 Car Application
As a final test we put the battery management to use in a real world car application. Asexplained above a Citroen C5 was retrofitted with a LiFePO4 battery pack. This car wasthen started and driven around for a number of times. Figure 7.17 shows one of the test drivecycles we recorded with the software.
We can distinguish a number of load cases in this cycle:
• Standby from 0 to 20 seconds
• Wakeup from 20 to 60 seconds
46
7 Evaluation
Figure 7.11: Common Mode rejection and linearity for the four individual channels
47
7 Evaluation
Figure 7.12: Absolute and relative accuracy for the four individual channels
48
7 Evaluation
Figure 7.13: Common Mode rejection for fast changing voltages
49
7 Evaluation
Figure 7.14: Total Voltage measurement error
50
7 Evaluation
Figure 7.15: Total Current measurement error
51
7 Evaluation
Figure 7.16: Shutdown during ignition of the car
Figure 7.17: Test Car driving cycle
52
7 Evaluation
• Ignition at 60 seconds with current draw of ≈ 350A
• Charging phase where the alternator charges the battery while the diesel engine isrunning. Charge current ≈ 50A till 200 seconds
• Shutdown where current is again drawn from the battery up to 350 seconds
• Subsequent Power down of the various systems
Looking closer at the current and voltage curves we can see that the current has a huge rippleof ≈ 10A, which is also represented in the single cell voltage measurements seen in Figure7.18
Figure 7.18: Test Car driving cycle single cell plot
The reason for this lies in the way a car alternator operates. It is basically a dc excitedsynchronous generator with a regulator that changes the excitation current so that the outputvoltage of the alternator stays at ≈ 14.2V and the output current stays below the maximumrated current for the alternator. The output of the alternator therefore is a 3-phase ACvoltage which is then rectified by a 6 diode network. The battery is then used as a buffer tostabilize the board voltage, leading to the ripple in current flowing to the battery.
53
8 Conclusion
From the measurements performed and discussed in the evaluation section 7 we can concludethat the replacement of existing lead acid batteries with modern LiFePo4 based battery packsis a viable and promising solution for the problems car manufacturers are facing with todaysimplementation. The 4 series connected LiFe cells match very well with the voltage domain ofa classic 12V battery and therefore do not require any changes in the alternator or the boardpower system. The life management and balancing board discussed in this thesis performs allthe necessary functions to safely operate such a new cell stack in any classic car applicationnicely. Therefore it provides a ready-made swap in solution for existing cars as well as a goodtesting platform. With the addition of a full featured battery state of charge and state ofhealth diagnostic algorithm it will also support advanced features like active breaking andmild hybrid support.
54
9 APPENDIX
9.1 USB2LIN Schematic and Layout
9.2 LiFe Battery Management Schematic and Layout
9.3 3D Drawing of the Retrofit Battery
55
9 APPENDIX
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RA
0/IO
CA
0/D
+/PG
D19
RA
1/IO
CA
1/D
-/PG
C18
RC
1/A
N5/
C12
IN-/I
NT1
/Vre
f-15
RC
2/A
N6/
P1D
/C12
IN2-
/CV
ref/I
NT2
14
RA
4/A
N3/
IOC
A3/
OSC
2/C
LKO
UT
3
VU
SB17
RC
0/A
N4/
C12
IN+/
INT0
/Vre
f+16
RB
5/A
N11
/IOC
B5/
RX
/DT
12
RB
7/IO
CB
7/TX
/CK
10
RC
3/A
N7/
P1C
/C12
IN3-
/PG
M7
RC
4/P1
B/C
12O
UT/
SRQ
6
RC
5/C
CP1
/P1A
/T0C
KI
5
RA
3/IO
CA
3/M
CLR
/VPP
4
VD
D1
RB
4/A
N10
/IOC
B4/
SDI/S
DA
13
RB
6/IO
CB
6/SC
K/S
CL
11
RC
7/A
N9/
SDO
/T1O
SCO
9
RC
6/A
N8/
SS/T
13C
KI/T
1OSC
I8
VSS
20
RA
5/IO
CA
5/O
SC1/
CLK
IN2
U1
PIC
18F1
4K50
GN
D
VC
C
D-
D+
GN
DV
CC
R1
150K
100n
F
C1
C08
05
470n
F
C2
C08
05
D+
D-V
CC
12
Y1
12M
Hz
22pF
C4
C08
0522
pF
C3
C08
05
GN
D
D1
LED
2
D2
LED
2
R2
470R
R3
470R
GN
DR
X
TX
1 2 3
P1 Hea
der 3
GN
D
TXRX
123
P2 Hea
der 3
GN
D
EN1
VSU
P2
LIN
3
VSS
4R
X5
TX6
RES
ET7
VC
C8
U2
AS8
530
RX
TX
VC
C2
POK
4
EN1
GN
D7
FB8
LX5
SWVIN3
SWVOUT6 GN
D_B
9
U3
AS1
340
VSU
P47
0nF
C5
C08
05G
ND
VC
C
GN
D
GN
D
R4
100K
R5
860K
D3
PMEG
4010
BEA
VSU
P
4u7
C6
C12
102u
2
C7
C12
10
GN
D
L1 LPS4
018-
682M
L_
GN
D
S2SW-P
B
VC
C R7
10K
7 62345 1
89J1 U
SB-C
ON
1 2 3 4 5
J3 PicK
it
MC
LR
MC
LR
VC
CG
ND
D+
D-
USB
2 L
IN
R8
1K
Figure 9.1: USB2LIN Schematic
56
9 APPENDIX
PAC102
PAC101COC1
PAC202
PAC201
COC2
PAC302
PAC301
COC3
PAC402
PAC401
COC4
PAC502
PAC501
COC5
PAC602
PAC601
COC6
PAC702
PAC701
COC7
PAD102
PAD101CO
D1PAD2
02PAD2
01COD2
PAD3
02PA
D301CO
D3
PAJ106
PAJ105
PAJ104
PAJ103
PAJ102
PAJ108
PAJ101
PAJ109
PAJ107
PAJ10MH2
PAJ10MH1
COJ1
PAJ301
PAJ302
PAJ303
PAJ304
PAJ305
COJ3
PAL102PAL101
COL1
PAP101
PAP102
PAP103
COP1
PAP201
PAP202
PAP203
COP2
PAR102
PAR101
COR1
PAR202
PAR201 COR2PAR3
02PAR3
01CO
R3
PAR402
PAR401
COR4
PAR502
PAR501
COR5
PAR701
PAR702COR7
PAR802
PAR801
COR8
PAS201
PAS202
COS2
PAU1
011
PAU1
012
PAU1
013
PAU1
014
PAU1
015
PAU1
016
PAU1
017
PAU1
018
PAU1
019
PAU1
020
PAU1010
PAU109
PAU108
PAU107
PAU106
PAU105
PAU104
PAU103
PAU102
PAU101
COU1
PAU2
05
PAU206
PAU2
07
PAU208
PAU2
04
PAU203
PAU2
02
PAU201
COU2
PAU309PA
U308
PAU307
PAU3
06
PAU305
PAU304
PAU3
03
PAU302
PAU3
01CO
U3
PAY102
PAY101
COY1
Figure 9.2: USB2LIN Layout
57
9 APPENDIX
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FD_O
UT
TSEC
HTS
ECL
TSEC
H
TSEC
L
TRIG_IN_5V
CVT_NOK_5V
BD_OUT_5V
FD_OUTS
CLK
_5V
SD
I_5V
SD
O_5
V
C10 100n
F
C44.7u
F
D5
Q5
C11
D4
GN
D
GN
D
VB
AT
VB
AT
GN
D
5V_8
505
GN
D
GN
D
VSU
P
HR
SHL
HR
SH
H
SD
I
VC
CV
SS
SDO
SCLK
AV
SS
8510/INT
VC
C
8525/CS
RXlin
TXlin
8510/EN
HR
SHL
HRSHH
8510/CS
VSUP
VSS
LIN
VSS
VCC
R2
100R
C1
100n
F
D2
SU
P D
iode
C8
100n
F
R1
100R
D1
DIO
DE
C2
100n
F
C9
100n
F
RSH
L1
VR
EF2
AG
ND
3
AV
DD
4
AV
SS5
ETR
6
ETS
7
VSENSE_GND 9
LIN 10
VSS 11
VSENSE 12
VSUP 13
VCC 15
CSB 16
SCLK
17SD
O18
DV
SS19
DV
DD
20C
HO
P_C
LK21
MEN
22SD
I23
CLK
24
INT26 CST27 TX28 RX29 RESET30 EN31 RSHH32
VSE
NSE
_IN
8
EPAD 33
U2 AS
8515
C7
200n
F
C6
22uF
AV
SS
LIN
12
P1 LIN
SHU
NTH
8510
/CLK
C3
1.2n
F To m
eet G
erm
anO
EM E
MC
requ
irem
ents
8505
/CS_
5V
BA
T1B
AT2
BA
T3B
AT4
BA
T_D
IV_I
N
Q1
BSS
123
Q2
BSS
123
Q3
BSS
123
Q4
BSS
123
BA
T1B
AT2
BA
T3B
AT4
AV
SS
VSS
VB
AT
BA
T_D
IV_I
N
GN
D
VB
AT
GN
D
BAT1
BAT2 BAT1
BAT3 BAT2
BAT4 BAT3
GN
D
D3
SU
P D
iode
J5V
BA
L_SE
LEC
T3V
3
A1
1
VCCA2
A2
3
A3
4
A4
5
A5
6
A6
7
A7
8
A8
9
OE
10
GND 11
B8
12B
713
B6
14B
515
B4
16B
317
B2
18
VCCB19
B1
20
U3
TXS0
108
5V_8
505
3V3
GN
D
R11
100K
R4
91K
0.1
%R
575
K 0
.1%
R6
47K
0.1
%R
724
K 0
.1%
R8
1K 0
.1%
8505
/CS_
5VS
CLK
_5V
SD
I_5V
SD
O_5
V
BD
_OU
T_5V
CV
T_N
OK
_5V
TRIG
_IN
_5V
8505
/CS
SCLK SD
ISD
O
BD
ON
EC
VT_
NO
K85
05/T
RIG
8505
/WA
KE
8505
/OE
SD
OS
DI
SC
LK
8525
/CS
8510
/CS
8510
/CS
8525
/CS
RX
linTX
linTX
linR
Xlin
8510
/EN
8510
/EN
8510
/INT
8510
/INT
S1S2
S3S4
R12
GN
DR13
300K
R14
100K
8505/VREF
8505
/VR
EF
1 2 3 4 5
J1 BA
TT_C
ONB
AT2
BA
T3B
AT4
BA
T1 GN
D
VB
AT
1 2
J2 BA
T_C
ON
_2G
ND
VB
AT
S1 100u
R
SHU
NTL
D6
D7
D8
D9
1 4
10 72 5
11 83 6
12 9
T1 WE-
FLEX
749
1961
11
GN
D
Q7
BSS
123
C5
100n
F
AS8506
TSEC
H1
TSEC
L2
VC
ELL7
3
VC
ELL6
4
VC
ELL5
5
VC
ELL4
6
VC
ELL3
7
VC
ELL2
8
VC
ELL1
9
C_G
ND
10
VREF_IN 12GND 13TRIG_IN 14CLK_IN 15CVT_NOK_OUT 16BD_OUT 17FD_OUT 18WAKE_IN 19
SDO
21SD
I22
SCLK
23C
S24
CEL
L_TH
U25
CEL
L_TH
L26
TEM
P_IN
227
TEM
P_IN
128
V5V
30
V5V_IN31
WAKE_OUT32
FD_IN33
BD_IN34
CVT_NOK_IN35
CLK_OUT36
TRIG_OUT37
VSUP38
MS_SL39
GND_PLATE 41NC 11
NC_T 20
REF
_T29
VREF_H40
U1
8505
/VR
EF_
OU
T
8505
/VR
EF_
OU
T
GN
D
R15
0R
VB
AT
R16
0R
PIC101 PIC102COC1
PIC201 PIC202COC2
PIC301 PIC302
COC3
PIC401
PIC402COC4
PIC501 PIC502COC5
PIC601 PIC602
COC6
PIC701 PIC702
COC7
PIC801
PIC802
COC8
PIC901
PIC902
COC9
PIC100
1
PIC100
2
COC1
0
PIC110
1
PIC110
2COC1
1
PID101
PID102
COD1
PID201PID202
COD2
PID301 PID302
COD3
PID401
PID403
COD4
PID501PID503COD5
PID601PID602CO
D6
PID701PID702CO
D7
PID801PID802CO
D8
PID901PID902CO
D9
PIJ101
PIJ102
PIJ103
PIJ104
PIJ105
COJ1 PI
J201
PIJ202
COJ2
PIJ501
PIJ502
COJ5
PIP101
PIP102
COP1
PIQ101
PIQ102PIQ103 COQ1
PIQ201
PIQ202PIQ203 COQ2
PIQ301
PIQ302PIQ303 COQ3
PIQ401
PIQ402PIQ403 COQ4
PIQ501
PIQ502PIQ503 COQ5
PIQ701
PIQ702PIQ703 COQ7
PIR101
PIR102
COR1
PIR201
PIR202
COR2
PIR401 PIR402COR4
PIR501 PIR502COR5
PIR601 PIR602COR6
PIR701 PIR702
COR7
PIR801 PIR802
COR8
PIR1101 PIR1102COR11
PIR1201 PIR1202COR12
PIR1301 PIR1302
COR1
3
PIR1401 PIR1402
COR1
4
PIR1501 PIR1502
COR15
PIR1601
PIR1602
COR16
PIS101 PIS102PIS103
PIS104
COS1
PIT101
PIT102
PIT103
PIT104
PIT105
PIT106
PIT107
PIT108
PIT109
PIT1010
PIT1011
PIT1012
COT1
PIU101
PIU102
PIU103
PIU104
PIU105
PIU106
PIU107
PIU108
PIU109
PIU1010
PIU1011PIU1012
PIU1013PIU1014
PIU1015PIU1016
PIU1017PIU1018
PIU1019PIU1020
PIU1021
PIU1022
PIU1023
PIU1024
PIU1025
PIU1026
PIU1027
PIU1028
PIU1029
PIU1030
PIU1031PIU1032
PIU1033PIU1034
PIU1035PIU1036
PIU1037PIU1038
PIU1039PIU1040 PIU1041
COU1
PIU201
PIU202
PIU203
PIU204
PIU205
PIU206
PIU207
PIU208
PIU209PIU2010PIU2011PIU2012
PIU2013PIU2015PIU2016
PIU2017
PIU2018
PIU2019
PIU2020
PIU2021
PIU2022
PIU2023
PIU2024
PIU2026PIU2027PIU2028PIU2029PIU2030PIU2031PIU2032
PIU2033
COU2
PIU301
PIU302PIU303
PIU304
PIU305
PIU306
PIU307
PIU308
PIU309
PIU3010
PIU3011
PIU3012
PIU3013
PIU3014
PIU3015
PIU3016
PIU3017
PIU3018
PIU3019PIU3020
COU3
PIC401
PIC501PIU1030
PIU3019PIU301
PIU1024
PIU3020
NL85
050C
S05V
PIR1101PIU3010
PIU307
PIR1302 PIR1401
PIU1012
NL85050VREF
PIR1601
PIU1040
NL85050VREF0OUT
PIQ701
PIU2024
NL85100CLK
PIU2016
NL85
100C
S
PIU2031
NL85
100E
N
PIU2026NL85100INT
PIU2027NL
8525
0CS
PIC102 PIC201
PIC302
PIC402
PIC502
PIC602PIC702
PIC801 PI
C901
PID201
PID601
PIJ105
PIJ202
PIP101
PIQ502
PIQ702
PIR802
PIR1102
PIR1402
PIS102
PIU1010
PIU1013
PIU1027
PIU1028
PIU1039
PIU1041
PIU205
PIU209PIU2011
PIU2019
PIU2033
PIU3011
NLAV
SS
NLVS
S
PID602PID701
PIJ104
PIR701
PIU109
NLBA
T1
PID702PID801
PIJ103
PIR601
PIU108
NLBA
T2
PID802PID901
PIJ102
PIR501
PIU107
NLBA
T3
PIQ102PIQ202
PIQ302PIQ402
PIR801
PIU206
NLBAT0DIV0IN
PIU1017
PIU3012
NLBD0OUT05V
PIU309
PIU308
PIU1016
PIU3013
NLCVT0NOK05V PIQ501
PIU1018
NLFD0OUT
PIC101PIR101
PIU2032NLHRSHH
PIC202PIR201
PIU201
NLHR
SHL
PIC301PIP102
PIU2010 NLLIN
PIC802
PIU202
PIC902
PIU203
PIC100
1
PIJ502
PIR1201
PIT101
PIC100
2 PID503
PIR1202
PID401
PIT107
PID501 PIQ503PIT106
PIQ103PIR402
PIQ203PIR502
PIQ303PIR602
PIQ403PIR702
PIQ703
PIU1019
PIR1301PIR1502PIR1602
PIS101
PIT102
PIT104
PIT103
PIT105
PIT108
PIT1010
PIT109
PIT1011
PIU1011PIU1015
PIU1020
PIU1025
PIU1026
PIU1029
PIU1032PIU1036
PIU1037
PIU207
PIU208
PIU2021
PIU2022
PIU2030
PIU306
PIU3015
PIU2029NL
RXli
n
PIQ401
PIQ301
PIQ201
PIQ101
PIU2017
PIU303
NLSCLK
PIU1023
PIU3018
NLSC
LK05
V
PIU2023
PIU304
NLSDI
PIU1022
PIU3017
NLSD
I05V
PIU2018
PIU305
NLSD
O
PIU1021
PIU3016
NLSD
O05V
PIR102
PIS103
NLSHUNTH
PIR202
PIS104
NLSHUNTL
PIU1014
PIU3014
NLTRIG0IN05V
PIC110
1
PID302
PID403
PIU101
NLTS
ECH
PIC110
2
PID301
PIT1012
PIU102
NLTS
ECL
PIU2028NL
TXli
n
PID101
PID202
PID902
PIJ101
PIJ201
PIJ501
PIR401
PIR1501
PIU103
PIU104
PIU105
PIU106
PIU1031PIU1033
PIU1034PIU1035
PIU1038
PIU2012
NLBA
T4
PIU204
PIU2015
PIU2020
PIU302NLVCC
PIC601PIC701
PID102
PIU2013 NLVSUP
Figure 9.3: LiFe Management Schematic Page 1
58
9 APPENDIX
11
22
33
44
DD
CC
BB
AA
Title
Num
ber
Rev
isio
nSi
ze A4
Dat
e:11
.04.
2012
Shee
t o
fFi
le:
Z:\T
rans
fer\.
.\mcu
.Sch
Doc
Dra
wn
By:
VC
C1
P50/
INT0
0_0/
AIN
0_2/
SIN
3_1
2
P51/
INT0
1_0/
BIN
0_2/
SOT3
_13
P52/
INT0
2_0/
ZIN
0_2/
SCK
3_1
4
P39/
DTT
I0X
_0/A
DTG
_25
P3A
/RTO
00_0
/TIO
A0_
1/R
TCC
O_2
/SU
BO
UT_
26
P3B
/RTO
01_0
/TIO
A1_
17
P3C
/RTO
02_0
/TIO
A2_
18
P3D
/RTO
03_0
/TIO
A3_
19
P3E/
RTO
04_0
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A4_
110
P3F/
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05_0
/TIO
A5_
111
VSS
12
C13
VC
C14
P46/
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15
P47/
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16
INIT
X17
P49/
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018
P4A
/TIO
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019
PE0/
MD
120
MD
021
PE2/
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22
PE3/
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VSS
24P1
0/A
N00
25P1
1/A
N01
/SIN
1_1/
INT0
2_1/
FRC
K0_
2/IC
02_0
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UP1
26P1
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N02
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1_1/
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AV
CC
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P23/
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CK
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P22/
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07/S
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1/SI
N0_
0/IN
T06_
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KU
P236
P00/
TRST
X37
P01/
TCK
/SW
CLK
38P0
2/TD
I39
P03/
TMS/
SWD
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P04/
TDO
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P0F/
NM
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UH
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P60/
SIN
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CC
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046
P81/
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P047
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D
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D
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D3V3
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11
22
33
44
55
66
77
88
99
1010
1111
1212
1313
1414
1515
1616
1717
1818
1919
2020
J12
JTA
GG
ND
nTRST
TDI
TMS
TCK
RTC
KTD
ORES
ETDBGRQ
JTAG_5V
TDO
TDI
nTRST
TMS
TCK
RES
ET
X0 X1
D-
D+
GN
D
7 62345 1
89J1
0
USB
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N
D+
D-
SIN0
SIN1
SOT0
SOT1
SCK1
TXlin
RX
lin
SCLK
SDO
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8510
/CS
8525
/CS
8510
/EN
GN
D
8505
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BD
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E
CV
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8505
/TR
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8505
/CS
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/WA
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8510
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12
Y1
4MH
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C23
12pF
C24
12pF
GN
D
X0 X1
MD0
R20
27R
R21
27R
Q10
BC
857B
R22
1K5
R23
2K2
R24
10K
3V3
3V3
UHCONX
3V3
UHCONX
S1S2S3S4
J13
PRO
G_J
MP
MD0
R25
1K R26
10K
GN
D
3V3
1 2 3
J11
UA
RT0
SOT0
SIN0 GN
D
P_SW_1
P_SW_2
3V3 R
2710
K
RES
ET
LED
GN
D
D10
LED
LED
R28
470R
USB_VCC
Q11
IRFM
L824
4TR
PBF
Q12
IRFM
L824
4TR
PBF
GN
D
P_SW_1
P_SW_2
123J1
5B
ATT
_SW
ITC
H
VB
AT
3V3
R29
20K
R30
10K
GN
D
INT15_1
INT15_1
C21
100nF
C22
100nF
USB_D+
USB_D-
I/O 1
1
GN
D2
I/O 2
3I/O
24
VB
US
5
I/O 1
6U
5
USB
LC6-
2
3V3
PIC2001 PIC2002CO
C20
PIC2101 PIC2102CO
C21
PIC2201 PIC2202CO
C22
PIC2301 PIC2302COC23
PIC2401 PIC2402COC24
PID1001 PID1002
COD10
PIJ1
001
PIJ1
002
PIJ1
003
PIJ1
004
PIJ1005
PIJ1
006
PIJ1
007
PIJ1
008
PIJ1009COJ
10
PIJ1101
PIJ1102
PIJ1103
COJ11
PIJ1201
PIJ1202
PIJ1203
PIJ1204
PIJ1205
PIJ1206
PIJ1207
PIJ1208
PIJ1209
PIJ12010
PIJ12011
PIJ12012
PIJ12013
PIJ12014
PIJ12015
PIJ12016
PIJ12017
PIJ12018
PIJ12019
PIJ12020
COJ12
PIJ1301
PIJ1302
COJ13
PIJ1501PIJ1502
PIJ1503COJ15
PIQ1001
PIQ1002 PIQ1003
COQ10
PIQ1101
PIQ1102PIQ1103COQ11
PIQ1201
PIQ1202PIQ1203COQ12
PIR2001
PIR2002
COR2
0
PIR210
1PIR
2102
COR2
1
PIR2201 PIR2202
COR2
2
PIR2301
PIR2302
COR23
PIR2401PIR2402CO
R24
PIR2501 PIR2502
COR2
5
PIR2601 PIR2602
COR2
6
PIR2701 PIR2702COR27
PIR2801 PIR2802COR28
PIR2901
PIR2902COR29
PIR3001PIR3002COR
30
PIU401
PIU402
PIU403
PIU404
PIU405
PIU406
PIU407
PIU408
PIU409
PIU4010
PIU4011
PIU4012
PIU4013
PIU4014
PIU4015
PIU4016
PIU4017
PIU4018
PIU4019
PIU4020
PIU4021
PIU4022
PIU4023
PIU4024
PIU4025
PIU4026
PIU4027
PIU4028
PIU4029
PIU4030
PIU4031
PIU4032
PIU4033
PIU4034
PIU4035
PIU4036
PIU4037
PIU4038
PIU4039
PIU4040
PIU4041
PIU4042
PIU4043
PIU4044
PIU4045
PIU4046
PIU4047
PIU4048
COU4
PIU501
PIU502
PIU503
PIU504
PIU505
PIU506
COU5
PIY101PIY102 COY1
PIC2101PIC2201
PIJ1201
PIQ1002PIR2402
PIR2501
PIR2701
PIU401
PIU4014
PIU4031
PIU4045
PIU4018
PIU409
PIU4016
PIU4019
PIU4011
PIU405
PIU404
PIU406
PIU4010
PIC2001
PIU4013
NLC
PIU4015
PIR2002
PIR2202
PIU4047
NLD0
PIR210
2
PIU4046
NLD0
PIJ12017
NLDBGRQ
PIC2002PIC2102
PIC2202
PIC2302 PIC2401
PIJ1
004
PIJ1005
PIJ1
006
PIJ1
007
PIJ1
008
PIJ1009
PIJ1103
PIJ1204
PIJ1206
PIJ1208
PIJ12010
PIJ12012
PIJ12014
PIJ12016
PIJ12018
PIJ12020
PIQ1102PIQ1202
PIR2602
PIR2802
PIR3001
PIU4012
PIU4020
PIU4024
PIU4033
PIU4048
PIU502
PIR2901
PIU4044
NLIN
T150
1
PIJ12019
NLJTAG05V
PID1001
PIU407
NLLE
D
PIJ1302 PIR2601
PIU4021
NLMD0
PID1002 PIR2801
PIJ1
001
PIR2902
PIR3002
PIU505
PIJ1202
PIJ1301PIR2502
PIJ1501
PIQ1203
PIJ1503
PIQ1103
PIQ1001
PIR2301
PIQ1003 PIR2201
PIR2001
PIU506
PIR210
1PIU504
PIU4032
PIJ1203
PIU4037
NLnT
RST
PIQ1101
PIU408
NLP0SW01
PIQ1201
PIU4042
NLP0SW02
PIJ12015
PIR2702
PIU4017
NLRESET
PIJ12011
NLRT
CK
PIU402
PIU4025
PIU4029
PIU4030
PIU4034
PIU4028
NLSC
K1
PIJ1102
PIU4036
NLSI
N0
PIU4026
NLSI
N1
PIJ1101
PIU4035
NLSO
T0
PIU4027
NLSO
T1
PIJ1209
PIU4038
NLTCK
PIJ1205
PIU4039
NLTD
I
PIJ12013
PIU4041
NLTDO
PIJ1207
PIU4040
NLTMS
PIU403
PIR2302
PIR2401
PIU4043
NLUHCONX
PIJ1
003
PIU501
NLUSB0D0
PIJ1
002
PIU503
NLUS
B0D0
NLUSB0VCC
PIJ1502PIC2301
PIU4022
PIY102NL
X0
PIC2402
PIU4023
PIY101NL
X1
Figure 9.4: LiFe Management Schematic Page 2
59
9 APPENDIX
PAC102
PAC101 COC1
PAC202
PAC201
COC2
PAC302
PAC301
COC3
PAC402
PAC401
COC4
PAC502
PAC501
COC5
PAC602
PAC601
COC6
PAC702
PAC701
COC7
PAC802
PAC801COC8 PAC90
2PAC9
01COC9
PAC100
2
PAC100
1CO
C10
PAC1102
PAC1101 COC1
1
PAC200
2PAC
2001
COC20PAC2
102
PAC2101
COC21
PAC2202
PAC2201
COC2
2
PAC2302PA
C2301COC23
PAC2402PAC
2401COC24
PAD1
01PA
D102
COD1
PAD202
PAD201 COD2
PAD302P
AD301
COD3
PAD401PAD402
PAD403COD4
PAD5
01
PAD5
02PA
D503COD5
PAD602
PAD601COD6
PAD702
PAD701COD7
PAD802
PAD801COD8
PAD902
PAD901COD9
PAD1001
PAD1002
COD1
0
PAJ105
PAJ104
PAJ103
PAJ102
PAJ101
COJ1
PAJ202
PAJ201
COJ2
PAJ502
PAJ501
COJ5
PAJ1007
PAJ1009
PAJ1001PAJ10
08PAJ1002PAJ1003PAJ1004PAJ1005
PAJ1006PAJ100
MH1PAJ100
MH2
COJ10
PAJ1103
PAJ1102
PAJ1101
COJ1
1
PAJ12020
PAJ12019
PAJ12018
PAJ12017
PAJ12016
PAJ12015
PAJ12014
PAJ12013
PAJ12012
PAJ12011
PAJ12010
PAJ1209
PAJ1208
PAJ1207
PAJ1206
PAJ1205
PAJ1204
PAJ1203
PAJ1202
PAJ1201
COJ1
2
PAJ1302
PAJ1301
COJ1
3
PAJ1501
PAJ1502
PAJ1503
COJ1
5PAP
101
PAP102
COP1
PAQ103
PAQ102
PAQ101
COQ1
PAQ203
PAQ202
PAQ201
COQ2
PAQ303
PAQ302
PAQ301
COQ3
PAQ403
PAQ402
PAQ401
COQ4
PAQ503
PAQ502
PAQ501
COQ5
PAQ703
PAQ702
PAQ701
COQ7
PAQ1001PAQ1002
PAQ1003
COQ10
PAQ1101
PAQ1102
PAQ1103
COQ1
1
PAQ1201
PAQ1202
PAQ1203
COQ1
2
PAR102
PAR101 COR1PAR2
02PAR20
1COR2
PAR402
PAR401
COR4
PAR502
PAR501
COR5
PAR602
PAR601
COR6
PAR702
PAR701
COR7
PAR802
PAR801
COR8
PAR1102
PAR1101COR11
PAR120
2
PAR1201
COR1
2
PAR1302
PAR1301
COR1
3
PAR1402
PAR1401
COR1
4
PAR1501
PAR1502
COR1
5
PAR160
2
PAR160
1CO
R16
PAR200
2
PAR200
1COR20
PAR210
2
PAR210
1
COR21
PAR2202
PAR2201
COR22
PAR230
2
PAR230
1
COR23
PAR240
2
PAR240
1
COR24
PAR250
2
PAR250
1
COR25
PAR260
2
PAR260
1
COR2
6
PAR2702
PAR2701
COR27
PAR280
2
PAR280
1COR28
PAR290
2
PAR290
1
COR29
PAR300
2
PAR300
1
COR30
PAS104
PAS103
PAS102
PAS101
COS1
PAT107
PAT108
PAT109
PAT101
0PAT
1011
PAT101
2
PAT106
PAT105
PAT104
PAT103
PAT102
PAT101
COT1
PAU1041
PAU1040PAU1039PAU
1038PAU1037PAU1036
PAU1035PAU1034PAU
1033PAU1032PAU1031
PAU1030
PAU102
9PAU1028
PAU1027
PAU1026
PAU1025
PAU1024
PAU102
3PAU1022
PAU1021
PAU1020PAU1019PAU1018PAU1017PAU1016PAU1015PAU1014PAU1013
PAU1012PAU1011PAU1010
PAU109
PAU108
PAU107
PAU106
PAU105
PAU104
PAU103
PAU102
PAU101
COU1
PAU201
PAU202
PAU203
PAU204
PAU205
PAU206
PAU207
PAU208
PAU209PAU2010
PAU2011PAU2012
PAU2013PAU2014
PAU2015PAU2016
PAU2017
PAU2018
PAU2019
PAU2020
PAU2021
PAU2022
PAU2023
PAU2024
PAU2025PAU2026
PAU2027PAU2028
PAU2029PAU2030
PAU2031PAU2032 PAU2
033COU2
PAU301PAU302PAU303PA
U304PAU305PAU306PAU3
07PAU308PAU309PAU301
0
PAU3020PAU3019PAU3018P
AU3017PAU3016PAU3015
PAU3014PAU3013PAU3012P
AU3011COU3
PAU4048PAU4047PAU4046PAU4045PAU
4044PAU4043PAU4042PAU4041PAU404
0PAU4039PAU4038PAU4037 P
AU4036
PAU4035
PAU4
034
PAU4
033
PAU4032
PAU4031
PAU4030
PAU4029
PAU4
028
PAU4027
PAU4026
PAU4025
PAU4024PAU4023PAU4022PAU4021PAU4020PAU4019PAU4018PAU4017PAU4016PAU4015PAU4014PAU4013PAU4012
PAU4011
PAU4010
PAU409
PAU408
PAU407
PAU406
PAU405
PAU404
PAU403
PAU402
PAU401
COU4
PAU506PAU
505PAU504PAU50
3PAU5
02PAU50
1
COU5
PAY1
02PA
Y101
COY1
PAC401
PAC501
PAU1030
PAU3019 PAU301
PAU4018
PAU1024
PAU3020
PAR1101
PAU3010
PAU409
PAU307
PAU4016PAR1
302
PAR1401
PAU1012
PAR160
1
PAU1040
PAQ701
PAU4019
PAU2024
PAU2016PAU4011
PAU2031
PAU405
PAU2026PAU404
PAU2027
PAU406
PAC102PAC201
PAC302
PAC402
PAC502
PAC602
PAC702
PAC801
PAC901
PAC200
2
PAC2102PAC2202
PAC2302
PAC2401
PAD201
PAD601
PAJ105
PAJ202
PAJ1004PAJ1005PAJ10
06
PAJ1007
PAJ1008
PAJ1009
PAJ1103
PAJ1204
PAJ1206
PAJ1208
PAJ12010
PAJ12012
PAJ12014
PAJ12016
PAJ12018
PAJ12020
PAP101
PAQ502
PAQ702
PAQ1102
PAQ1202
PAR802
PAR1102
PAR1402
PAR260
2
PAR280
2
PAR300
1
PAS102
PAU1010
PAU1013
PAU1027
PAU1028
PAU1039 PAU1041
PAU205
PAU209PAU2011
PAU2019
PAU2033
PAU3011
PAU4012
PAU4020PAU4024PA
U403
3
PAU4048PAU502
PAD602
PAD701
PAJ104
PAR701
PAU109
PAD702
PAD801
PAJ103
PAR601
PAU108
PAD802
PAD901
PAJ102
PAR501
PAU107
PAD1
01PAD2
02
PAD902
PAJ101
PAJ201
PAJ501
PAJ1502
PAR401
PAR1501
PAU103
PAU104
PAU105
PAU106
PAU1031PAU1033
PAU1034PAU1035PAU1038
PAU2012
PAQ102
PAQ202
PAQ302
PAQ402
PAR801
PAU206
PAU1017
PAU3012 PAU309
PAU4010
PAC200
1PAU4013
PAU308
PAU4015PAU1016
PAU3013
PAR200
2
PAR2202
PAU4047PAR210
2
PAU4046
PAJ12017
PAQ501
PAU1018
PAC101
PAR101
PAU2032
PAC202
PAR201
PAU201
PAR290
1
PAU4044
PAJ12019
PAD1001
PAU407
PAC301
PAP102
PAU2010
PAJ1302
PAR260
1
PAU4021
PAC802
PAU202
PAC902
PAU203
PAC100
1 PAJ502PAR1
201
PAT101
PAC100
2PAD5
03
PAR120
2
PAD401PAT
107PA
D501
PAQ503
PAT106
PAD1002
PAR280
1
PAJ1001PAR
2902
PAR300
2
PAU505
PAJ1301
PAR250
2
PAJ1501
PAQ1203
PAJ1503
PAQ1103
PAQ103
PAR402
PAQ203
PAR502
PAQ303
PAR602
PAQ403
PAR702
PAQ703
PAU1019
PAQ1001PAR230
1PAQ1003PAR22
01
PAR1301
PAR1502
PAR160
2
PAR200
1
PAU506
PAR210
1
PAU504
PAT102
PAT104
PAT103
PAT105
PAT108
PAT101
0PAT
109
PAT101
1
PAJ1203
PAU4037
PAQ1101
PAU408
PAQ1201
PAU4042
PAJ12015PAR27
02
PAU4017
PAJ12011
PAU2029PAU402
PAQ401
PAU4025
PAQ301
PAU4029
PAQ201
PAU4030
PAQ101
PAU4
034
PAU2017
PAU303
PAU4
028
PAU102
3
PAU3018
PAU2023
PAU304
PAU4027
PAU1022
PAU3017
PAU2018
PAU305
PAU4026
PAU1021
PAU3016
PAR102
PAS103
PAR202
PAS104
PAJ1102
PAU4036PAJ1
101
PAU4035
PAJ1209
PAU4038
PAJ1205
PAU4039 PAJ12013
PAU4041
PAJ1207
PAU4040
PAU1014
PAU3014
PAC1101PAD302PAD403
PAU101
PAC1102
PAD301
PAT101
2
PAU102
PAU2028PAU403
PAR230
2PAR
2401
PAU4043
PAJ1003PAU50
1
PAJ1002PAU503
PAC2101
PAC2201
PAJ1201
PAQ1002PAR240
2
PAR250
1
PAR2701
PAU204
PAU2015
PAU2020
PAU302
PAU401
PAU4014
PAU4031
PAU4045
PAC601
PAC701
PAD1
02
PAU2013
PAC2301
PAU4022
PAY1
02
PAC2402
PAU4023 PAY1
01
Figure 9.5: LiFe Management Layout
60
9 APPENDIX
212
274
134
battery_packGEWICHT:
A4
BLATT 1 VON 1MASSSTAB:1:2
ZEICHNUNGSNR.
BENENNUNG:
ÄNDERUNGZEICHNUNG NICHT SKALIEREN
WERKSTOFF:
DATUMSIGNATURNAME
ENTGRATENUND SCHARFEKANTENBRECHEN
OBERFLÄCHENGÜTE:WENN NICHT ANDERS DEFINIERT:BEMASSUNGEN SIND IN MILLIMETEROBERFLÄCHENBESCHAFFENHEIT:TOLERANZEN: LINEAR: WINKEL:
QUALITÄT
PRODUKTION
GENEHMIGT
GEPRÜFT
GEZEICHNET
Figure 9.6: Long side board
61
List of Figures
1.1 Typical car battery system . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.2 Diagram of the 4 lead-acid battery charging phases [24] . . . . . . . . . . . . 91.3 Influence of the discharge current on the usable capacity [5] . . . . . . . . . . 101.4 Influence of the discharge current on the usable capacity [4] . . . . . . . . . . 101.5 Influence of the discharge current on the cycle life [5] . . . . . . . . . . . . . . 11
2.1 Comparison of energy density of various battery types [20] . . . . . . . . . . . 132.2 Comparison of discharge curves of various battery types [7] . . . . . . . . . . 132.3 Plot of charging operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.4 Plot of discharging operation at various discharge rates . . . . . . . . . . . . . 162.5 Plot of discharging operation at various temperatures . . . . . . . . . . . . . 162.6 Block diagram of the AS8505/06 chip including peripheral components . . . . 17
3.1 Typical LIN network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.2 LIN Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.3 LIN Break field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.4 LIN Sync field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.5 LIN PID field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.6 LIN Master Task [21]p.41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.7 LIN Slave Task [21]p.43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1 USB2LIN Software Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.2 HID Bootlader after successful flashing operation . . . . . . . . . . . . . . . . 25
5.1 Battery Management Hardware Block Diagram . . . . . . . . . . . . . . . . . 285.2 Secondary current of the flyback transformer . . . . . . . . . . . . . . . . . . 295.3 LiFe Management Main Block Diagram . . . . . . . . . . . . . . . . . . . . . 325.4 LiFe Management LIN Block Diagram . . . . . . . . . . . . . . . . . . . . . . 335.5 LiFe Management AS8515 Interrupt Block Diagram . . . . . . . . . . . . . . 345.6 AS8505 state diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.1 PC-Software screenshot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366.2 PC-Software calibration tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.1 Rendering of the Battery Assembly . . . . . . . . . . . . . . . . . . . . . . . . 397.2 Citroen C5 with replacement battery installed . . . . . . . . . . . . . . . . . . 407.3 Citroen C5 replacement battery closeup . . . . . . . . . . . . . . . . . . . . . 417.4 4Cell LiFePo4 Pack from TopFuel . . . . . . . . . . . . . . . . . . . . . . . . . 417.5 Balancing with external supply . . . . . . . . . . . . . . . . . . . . . . . . . . 427.6 Balancing with internal supply . . . . . . . . . . . . . . . . . . . . . . . . . . 427.7 Balancing failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437.8 Schematic of the portion of the AS8505/06 responsible for the problem . . . . 437.9 Balancing with Zener Diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447.10 Balancing with lower current . . . . . . . . . . . . . . . . . . . . . . . . . . . 447.11 Common Mode rejection and linearity for the four individual channels . . . . 477.12 Absolute and relative accuracy for the four individual channels . . . . . . . . 487.13 Common Mode rejection for fast changing voltages . . . . . . . . . . . . . . . 497.14 Total Voltage measurement error . . . . . . . . . . . . . . . . . . . . . . . . . 507.15 Total Current measurement error . . . . . . . . . . . . . . . . . . . . . . . . . 517.16 Shutdown during ignition of the car . . . . . . . . . . . . . . . . . . . . . . . 527.17 Test Car driving cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
62
List of Figures
7.18 Test Car driving cycle single cell plot . . . . . . . . . . . . . . . . . . . . . . . 53
9.1 USB2LIN Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569.2 USB2LIN Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579.3 LiFe Management Schematic Page 1 . . . . . . . . . . . . . . . . . . . . . . . 589.4 LiFe Management Schematic Page 2 . . . . . . . . . . . . . . . . . . . . . . . 599.5 LiFe Management Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 609.6 Long side board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
63
Bibliography
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[11] Microsoft visual studio. http://www.microsoft.com/germany/express/.
[12] µvision ide overview. http://www.keil.com/uvision/.
[13] Txb0108 product page. http://www.ti.com/product/txb0108.
[14] Tyco battery disconnect switch. http://www.te.com/catalog/pn/en/1-1414939-4?
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[15] Usblc6-2 product page. http://www.st.com/internet/analog/product/93353.jsp.
[16] We-flex flexible transformer for dc/dc converter. http://katalog.we-online.de/
kataloge/eisos/index.php?language=en&pf=WE-FLEX.
[17] Zedgraph. http://zedgraph.sourceforge.net/index.html.
[18] Sony recalls notebook computer batteries due to previous fires. http://www.cpsc.gov/
cpscpub/prerel/prhtml07/07011.html, 2006.
[19] Laptop fires prompt sony battery recall again. http://www.wired.com/gadgetlab/
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[20] Lifepo4 batteries: A breakthrough for electric vehicles. http://www.metaefficient.
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html, 2008.
[21] Lin specification package revision 2.2a. LIN Consortium, 2010.
[22] Microchip application libraries. http://www.microchip.com/stellent/idcplg?
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Bibliography
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65
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