EE 136 Final PresentationProfessor Dr. Zhou

Presented by:Cynthia David

AgendaAgenda Part 1, Chapter 22

Centering of Auxiliary Output Voltages on Multiple-Output Converters.

Part 1, Chapter 23 Auxiliary Supply Systems

Part 1, Chapter 24 Operation of Voltage-Stabilized Power

Supplies

Centering Auxiliary Output Voltages Centering Auxiliary Output Voltages on Multiple-Output Converterson Multiple-Output Converters

Problem Obtaining an absolute output voltage

value. Solution

Saturable reactors – small toroids Used to control voltage and current

control. Provides pulse width / timing

techniques

Centering Auxiliary Output Voltages Centering Auxiliary Output Voltages on Multiple-Output Converterson Multiple-Output Converters

Saturable ReactorsSaturable Reactors with a forward converter .with a forward converter .Vout = Vs × ton / ( ton + toff ) from Chapter Vout = Vs × ton / ( ton + toff ) from Chapter

21 Part 121 Part 1 ExampleExample

Given Vout = +12, -12, +5 Desire: 11.5 turns use 12 Higher Output Voltage is given ie. 12.7 ton = 15 µs toff = 18 µs

Centering Auxiliary Output Voltages Centering Auxiliary Output Voltages on Multiple-Output Converterson Multiple-Output Converters

Saturable ReactorsSaturable Reactors td = ton – required V × ton / (actual Vout )

= 15 - (12*15) / (12.7) = .827 µs

td is delay time, ton is on cycle, Vs = Vout ( ton + toff) / ton = 27.9 V . td = Np × ∆B × Ae / (Vs) Np is the primary turns, ∆B difference in remanance flux

from flux density saturation. Ae is the effective area of the core. Given ∆B = .4

Ae = Vs × td / ( Np × ∆B ) assume Np = 1.

Centering Auxiliary Output Voltages Centering Auxiliary Output Voltages on Multiple-Output Converterson Multiple-Output Converters

Saturable ReactorsSaturable Reactors Ae = Vs × td / ( Np × ∆B ) assume Np = 1. = 27.9*.827 µs / (1 * .4) = 57.7 mm^2

Centering Auxiliary Output Voltages Centering Auxiliary Output Voltages on Multiple-Output Converterson Multiple-Output Converters

ApplicationsApplications large industrial furnaces, welders and large industrial furnaces, welders and

high-power voltage regulators.high-power voltage regulators. Important ConceptImportant Concept

Depending on application, with Depending on application, with saturable reactors, decide to alter the saturable reactors, decide to alter the area or number of turn ratios to produce area or number of turn ratios to produce Vout.Vout.

Auxiliary Supply Systems

Auxiliary Supply Systems Provide power for control Drive circuits within the main switch-mode

unit. Need to be common to input and output

lines. Safety factors must be given

Creepage distance, isolation requirementsCreepage distance, isolation requirements Auxiliary supply methods must be Auxiliary supply methods must be

consideredconsidered

Auxiliary Supply Systems

Various auxiliary supply units Various auxiliary supply units 60 Hz Line Transformers 60 Hz Line Transformers

Energized before the main converter, allows Energized before the main converter, allows power available to the main switching mode. power available to the main switching mode.

Meets insulation and creepage requirements.Meets insulation and creepage requirements. Disadvantage: size & costDisadvantage: size & cost

Auxiliary Supply Systems

Auxiliary ConvertersAuxiliary Converters Two auxiliary power supplies from high Two auxiliary power supplies from high

frequency flyback converters.frequency flyback converters.

+ More efficient because energyIs returnted to the supply during Flyback period.

Auxiliary Supply Systems

Stabilized Auxiliary ConvertersStabilized Auxiliary Converters Modifications Zener Diode,Q2, winding Modifications Zener Diode,Q2, winding

P3P3 Maintains constant frequencyMaintains constant frequency

+ Maintains constant frequency. CanBe used as a clock.

Auxiliary Supply Systems

High-efficiency auxiliary supply.High-efficiency auxiliary supply. Includes a bridge rectifier supply the Includes a bridge rectifier supply the

converter & fan applicationconverter & fan application

+ Most efficient supply system+ Useful in 110-220V applications

Parallel Operation of Voltage-Parallel Operation of Voltage-Stabilized Power SuppliesStabilized Power Supplies

Voltage Stabilized Power Supplies Voltage Stabilized Power Supplies connected in parallel with high voltagesconnected in parallel with high voltages usually have small output resistancesusually have small output resistances big difference in current load!big difference in current load!

desire equal distribution in currentdesire equal distribution in current may cause output power supply to be may cause output power supply to be

overloaded! Domino Effect!overloaded! Domino Effect!

Parallel Operation of Voltage-Parallel Operation of Voltage-Stabilized Power SuppliesStabilized Power Supplies

Configurations of Power SuppliesConfigurations of Power Supplies Master Slave OperationMaster Slave Operation

Master controls the parallel supplies. P-Master controls the parallel supplies. P-terminal and Transistor 3 control currentterminal and Transistor 3 control current

KEY POINTS+ Similar output current - 20% Accurate - Limited to the number of supplies - If Master Fails, other units follow

Parallel Operation of Voltage-Parallel Operation of Voltage-Stabilized Power SuppliesStabilized Power Supplies

Configurations of Power SuppliesConfigurations of Power Supplies Voltage – Controlled Current SourceVoltage – Controlled Current Source

P terminal link adjust for output voltage, R1 P terminal link adjust for output voltage, R1 and R2 sense output current. and R2 sense output current.

KEY POINTS+ More accurate output current- Less percent of failure

Parallel Operation of Voltage-Parallel Operation of Voltage-Stabilized Power SuppliesStabilized Power Supplies

Configurations of Power SuppliesConfigurations of Power Supplies Force Current SharingForce Current Sharing

Compares Vref and V from R3 and R4 to maintain Compares Vref and V from R3 and R4 to maintain constant Voutput.constant Voutput.

A2 compares the currents and Rx alternates alters A2 compares the currents and Rx alternates alters V2 and Vout.V2 and Vout.

KEY POINTS+ More accurate output current+ Failure to one does not affect others.+ Redistribute load if others fail.+ Output voltage adjust itself to the average value of the independent units.

Parallel Operation of Voltage-Parallel Operation of Voltage-Stabilized Power SuppliesStabilized Power Supplies

Configurations of Power SuppliesConfigurations of Power Supplies Parallel Redundant OperationParallel Redundant Operation

Ensures maintenance of power in case Ensures maintenance of power in case supply fails. supply fails.

Diodes senses differences in Voutput.Diodes senses differences in Voutput.

KEY POINTS+ Failure to one does not affect others.+ Redistribute load if others fail

ConclusionConclusion

ReviewReview Centering of Auxiliary Output Voltages on Centering of Auxiliary Output Voltages on

Multiple-Output ConvertersMultiple-Output Converters Auxiliary Supply SystemsAuxiliary Supply Systems Parallel Operation of Voltage Stabilized Power Parallel Operation of Voltage Stabilized Power

Supplies.Supplies.