AC Battery Inverter (ACBI) Evaluation Board...of ACBI Evaluation Platform, a battery, battery...

Solantro Semiconductor Corp. AC Battery Inverter User’s Guide

Solantro Semiconductor Corp. DPD1127 rev. 2.2 1

AC Battery Inverter (ACBI) Evaluation Board User’s Guide

Document Number: DPD1127 rev. 2.2

The Solantro trademark is owned by Solantro Semiconductor Corp. Windows® is a registered trademark of Microsoft Corporation. Javatm is a trademark of Oracle® Corporation. Caution - Use of Controls, adjustments or performance of procedures other than those specified herein may result in injury or damage to equipment. © 2019 Solantro Semiconductor Corp. ("Solantro"). Strictly Confidential & Proprietary to Solantro. Use and disclosure of this document and its contents is subject to a Non-Disclosure Agreement between you and Solantro. Except as permitted by such agreements, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, recording, or otherwise, without the written permission of Solantro Semiconductor Corp. All rights reserved.



1. TableofContents1 Introduction.....................................................................................................................4

2 ACBIBenchTestingOverview...........................................................................................52.1 PowerInputRequirements.....................................................................................................52.2 CommunicationCables...........................................................................................................52.3 RequiredSoftwareandPrograms...........................................................................................5

3 SettinguptheACBIEvaluationPlatformhardware...........................................................63.1 PoweringtheACBI..................................................................................................................7

ACBIEvaluationPlatformcommunications.............................................................................73.1.1 BootingtheACBIBoard...........................................................................................................83.1.2

3.2 OperatingModeSelection......................................................................................................9

4 ProgrammingtheFlashMemory.....................................................................................11

5 HeliosParametersDescription........................................................................................12

6 TestingtheACBIEvaluationPlatform..............................................................................176.1 LEDStatusIndicators............................................................................................................176.2 PuttyTelemetryMessageDescription...................................................................................176.3 Grid-TiedModeTesting........................................................................................................18

BatteryCharging/DischarginginGrid-TiedMode................................................................196.3.1 FourQuadrantOperation......................................................................................................196.3.2

6.4 Off-GridModeTesting..........................................................................................................20

Revisionhistory....................................................................................................................22

Figures

Figure 1: ACBI Development Platform perspective view. ........................................................................... 6Figure 2: ACBI Evaluation Platform top view. ............................................................................................ 7Figure 3: DC Connected for ACBI ............................................................................................................... 8Figure 4: Putty Window start up text ............................................................................................................ 9Figure 5: ACBI code structures view in Helios .......................................................................................... 12Figure 6: Putty message description ........................................................................................................... 17Figure 7: Grid Tied test setup ..................................................................................................................... 18Figure 8: Islanded Mode with external AC source attached ....................................................................... 21

Tables

Table 1:Description of ACBI code structures ............................................................................................. 12Table 2: VAR structure variables description ............................................................................................. 13Table 3: SOFTWARE_INFO structure variables description .................................................................... 14Table 4: CAL structure variables description ............................................................................................. 14Table 5: CONST structure variables description ........................................................................................ 14Table 6: STATE structure variables description ......................................................................................... 15Table 7: LED Status indicator operation ..................................................................................................... 17Table 8: Power Notation ............................................................................................................................. 18Table 9: Example power targets .................................................................................................................. 19Table 10: Example 220V Off-Grid Mode voltage settings ......................................................................... 20



Warning – Electric Shock Hazard There are exposed, high voltages on the ACBI board. It should only be operated by experienced power supply professionals. ACBI evaluation board surfaces may be hot during operation. Do not touch. To evaluate this board as safely as possible, the following test configuration must be used:

• Follow the power-up and test procedure below.

• Only use isolated oscilloscope probes.

• Use isolated test equipment, with appropriate overcurrent and overvoltage protection.

• In Off-Grid / Islanded mode, the output is energized when the input is connected. Do not touch terminals while the board is energized



1 Introduction This document provides step-by-step instructions on how to operate the ACBI Evaluation Board using the evaluation firmware load. For information on establishing communication using the Helios user interface and PuTTY terminal applications see document: DPD1006 Helios User’s Guide. This document discusses physical connections, a high-level description of the evaluation firmware Helios variables, then an overview of operation.

The ACBI is capable of multiple modes of operation. Throughout this document ‘Off-Grid’ mode and ‘Islanded’ mode are used interchangeably to describe the ACBI running state where the ACBI acts to provide voltage and frequency regulation. In “Grid-Tied” mode, the ACBI requires a valid AC grid waveform, and acts as an AC current-source, sinking or sourcing real and/or reactive power to the grid.

The information, processes and procedures outlined in this document are intended for use only by trained and qualified personnel. The Helios Test and Control Tool functions only with Solantro Semiconductor Corp. chip sets.



2 ACBI Bench Testing Overview This chapter provides an overview of the ACBI Evaluation Platform system requirements. The Helios Test and Control Tool is used to program and test Solantro’s chipset firmware. Interaction with the running code on the development platform is performed through serial ports, using the Helios Test and Control Tool.

2.1 Power Input Requirements To boot the ACBI Evaluation Platform without starting up and performing power conversion, a single DC power supply capable of providing 40-60 VDC at approximately 3-4W is sufficient. A user may communicate with the processor, upgrade software, and inspect peripherals and data structures, but not start power conversion unless more powerful sources and sinks are provided for both AC and DC terminals. For the purposes of fully testing and evaluating the performance of ACBI Evaluation Platform, a battery, battery emulator (or a DC supply and DC load), and an AC source or grid emulator and AC load are required, all capable of at least 1kW power in/out.

2.2 Communication Cables Communication with the ACBI Evaluation Platform requires two USB to UART TTL isolators. UC-3100P isolated USB to UART TTL converter cables are provided as part of the kit. One cable is used for the Helios Test and Control Tool, and the other cable is for monitoring status through a terminal emulator such as PuTTY (this cable is optional, but highly recommended).

Note: The use of UC-3100P Isolated USB to UART TTL converter cables requires that you download and install a driver for the cable. The driver can be found at:

http://www.silabs.com/products/mcu/pages/usbtouartbridgevcpdrivers.aspx

2.3 Required Software and Programs You should have received Solantro’s Helios Test and Control Tool installation package along with the version of the firmware associated with the ACBI. If not, contact your Solantro representative. Additionally, PuTTY is used to interface with the board through the serial UART port. It can be downloaded from:

http://www.putty.org/

Further information can be found in the DPD1006 Helios User’s Guide.



3 Setting up the ACBI Evaluation Platform hardware This chapter explains how to set up the ACBI Evaluation Platform. The following illustrations show the ACBI Evaluation Platform from different perspectives.

Figure 1: ACBI Development Platform perspective view.



Figure 2: ACBI Evaluation Platform top view.

3.1 Powering the ACBI It is possible to power the ACBI from either a 240VRMS AC input or a 40 – 60 V DC input. Applying these voltages to either AC or DC input terminals will cause the Solantro SA4041 (IXC2) to boot.

Users unfamiliar with the ACBI and powering up the ACBI for the first time can use a power supply with a current limit of 100 mA.

ACBI Evaluation Platform communications 3.1.1

The ACBI has two UART ports for serial communications:

• HDLC UART port - This port provides access to real-time interaction with the IXC2, through Helios. It is an HDLC-framed UART port that sends or receives data, one packet at a time. Default bit rate is 115,200 bps.

• UART communications (COM) port - This port is for use with a terminal program, such as PuTTY, for monitoring, debug and status messages. This port is a simple UART that sends and receives data one byte at a time. Default bit rate is 115,200 bps.

The Helios Test and Control Tool (running on a PC) communicates with the ACBI using the HDLC protocol. The PC and the ACBI are physically connected by a UC-3100P Isolated USB to UART TTL converter cable. The USB connector plugs into the PC, and the TTL connector plugs into the HDLC UART port on the ACBI.

Refer to Figure 2 for the locations of the UART ports on the ACBI. Depending on the board build APC number, the UART port pins, for both COMS and HDLC ports, could be in slightly different locations on the board. The orientation of the connector may vary as well. This is important to note when connecting the UART cables as they could simply be connected



backwards. In the case of EPC0615 Rev. 1, the connector labelled “COM” refers to the PuTTY connection and the “HDLC” connector is for the Helios connection. In both cases, the white line on the cable aligns with the RX pin.

NOTE: If a UART port appears non-functional after applying power to the ACBI, the 3-pin SIP header may be backwards or mis-installed. Try reversing the connector. No damage will occur if these connectors are installed backwards.

After the appropriate communication cables are applied to the ACBI, refer to document: DPD1006 Helios User’s Guide for starting communication to the ACBI via Helios and PuTTY.

Booting the ACBI Board 3.1.2

After the proper software is installed (Helios, Putty, and SiLabs drivers), and serial connections made, it is possible to power the ACBI and talk to it. While as-shipped, the ACBI Evaluation Board will auto-boot into either Islanded or Grid-Tied operating modes as soon as power is applied (see Section 6), it is highly recommended that Helios and PuTTY be used to monitor and control the ACBI.

1. Make the appropriate communication attachments between the ACBI and your computer. Launch both applications. Set up a PuTTY port as defined in document DPD1006 Helios User’s Guide.

2. Connect a DC power supply to the ACBI DC power input using the included connector, pictured in Figure 3 and set the supply to 48VDC. If you wish to boot the ACBI from the AC side, make the appropriate connections to the AC terminals and set the power AC power supply to 240V. AC terminal location pictured in Figure 2.

Figure 3: DC Connected for ACBI

DO NOT REVERSE POLARITY OF THE DC CONNECTION, ALWAYS ATTACH POSITIVE OF THE BATTERY TERMINALS TO THE POSITIVE OF THE ACBI DC CONNCETOR. REVERSE POLARITY CAN LEAD TO DAMAGE OF THE ACBI BOARD.

3. Once all the required communication and voltage links are established, turn on the ACBI by applying the correct voltage to either AC (212 – 264 VRMS) or the DC (40 – 60 V) side.



If the COM port is properly connected and configured, you should see the text similar to that shown in Figure 4:

4. If after turning the power supply on, no text appears in the PuTTY session window, first try turning your power supply off, waiting until the voltage goes to zero (until the board capacitors discharge) and turn it back on. If the PuTTY still does not print anything, turn off the power supply and reverse the COM connector and then turn the power supply back on. Verify that two COM ports show up in your PC’s “Devices and Printers” Control-Panel screen, and that PuTTY is pointed to the correct COM port.

5. Launch Helios and connect with the proper project and COM port. If Helios refuses to connect, try reversing the HDLC UART connector on the ACBI and reboot the ACBI. The ACBI should now be powered with communication established.

3.2 Operating Mode Selection The ACBI Evaluation Board ships with the STATE.AUTO_START_ENABLED bit set to TRUE in the flash defaults.

• If the ACBI is booted using a 240VAC grid voltage and no DC source the inverter will boot then wait until a 40 – 60 V DC voltage is applied before starting power conversion. On conversion start the ACBI will enter Grid-Tied Mode.

Figure 4: Putty Window start up text



• If the ACBI is booted using a 40-60V DC connection and no AC voltage is present the inverter will start in Islanded mode.

There are two state fields that control operating mode. STATE.REQUEST_MODE can be set by the user to request either mode. The actual output-stage control is dictated by read-only variable STATE.CONTROL_MODE. Firmware makes the mode-change on behalf of users.

Grid-Tied Mode: The AC output stage operates in current-mode, and the AC output current is adjusted through closed-loop control to hit P and Q targets provided by the user. No voltage nor frequency regulation is provided, and the ACBI follows the grid using the IXC-2 internal AC PLL. In this mode grid current should appear sinusoidal with a phase angle that is dictated by the combined P and Q commands. If requested Q is zero, the current phase angle will be 0 or 180 degrees, depending on the sign of the P command.

Islanded Mode: In Islanded mode, the AC output stage also operates in current-mode, but the current controller is wrapped with a voltage-control loop that attempts to minimize the error with respect to an internal free-running AC reference voltage. This allows the ACBI to provide clean sinusoidal 240VAC to power off-grid loads from the DC battery.

Further, two “droop control” functions are provided that can allow paralleling of multiple ACBIs on the same AC bus in Islanded mode.

Voltage droop: This function effectively increases the low-frequency output impedance at the output of the inverter. As real AC power is drawn from the inverter, the reference voltage is decreased, and as real power is pushed into the inverter, the reference voltage is increased. Voltage droop is enabled through STATE.DBG_VOLTAGE_DROOP (default on), and the droop coefficient is specified in CONST.KV_ACTIVE_POWER_VOLTAGE_SLOPE.

Frequency droop: This function adjusts the frequency of the internal voltage reference away from nominal as a function of the reactive power measured at the output. This allows wireless synchronization of multiple inverters paralleled on an AC bus. Two inverters that are slightly out of phase with each other will experience opposite Q, and one will speed up, and the other slow down until the two inverters are in phase. Frequency droop is enabled through STATE.DBG_FREQUENCY_DROOP (default on), and the droop coefficient is specified in CONST.KW_REACTIVE_POWER_OMEGA_SLOPE.

For further information on paralleling of inverters using resistive droop, or output-stage voltage-mode control in hardware, please contact Solantro support.



4 Programming the Flash Memory Your ACBI Evaluation Board will have the most recent firmware loaded as of the hardware ship date. If Solantro releases another version of the firmware after the ACBI hardware is delivered, the program stored in the flash memory of the ACBI will have to be updated. There are two methods for programming the flash memory: programming the flash memory using the Helios Test and Control Tool; and programming the flash memory using PuTTY. Refer to DPD1006 Helios User’s Guide for detailed instructions on both methods. Programming the flash with firmware not provided by Solantro could result in irreparable damage to the board. Please do so at your own risk. If you wish to develop your own firmware for operation on the ACBI Evaluation Board or other hardware, please contact Solantro support. The ACBI Evaluation Board allows evaluation of the SA4041 (IXC-2) IC, the ACBI platform, and the evaluation firmware, but an enhanced firmware/source-code package is required for end-user code development and testing.



5 Helios Parameters Description Once the ACBI project is loaded into Helios, it is possible to view several code structures in the left navigation menu. Helios preferences are shown in white, firmware code structures are shown in blue, and IXC-2 peripheral device registers are shown in tan. A typical set of Helios favourites is shown below in Figure 5.

The ACBI Evaluation Board firmware ships with a firmware variant that provides visibility to the more important variables and structures needed for evaluation, while suppressing display of many internal variables. If greater understanding of the operating principles of the firmware is desired, including PID controllers, AC output PR controller, and details of hardware gate control of each stage, please contact Solantro support.

Table 1:Description of ACBI code structures

Helios Code Structure Description

Software Info Multiple variables describing the software version, uptime, and CPU utilization.

CAL Calibration variables. Most low-level ADC gain/offset etc suppressed.

STATE Multiple Boolean or Enumerated type variables defining and modifying the running

Figure 5: ACBI code structures view in Helios



state of the inverter.

CONST Constants and variables used to set limits and control targets. Typically writable.

VAR Dynamic variables and measurements set by firmware depending on the inverter’s operational state. Typically read only.

SOGI Second Order Generalized Integrator to extract the fundamental component of the grid current and voltage waveform. (Variables named accordingly)

BOXCAR Single grid cycle FIR filter for grid power, voltage, and current calculations. (Variables named accordingly)

PLOTTING A structure used to control real-time variable-capture and graphical display in Helios. Up to four signals may be simultaneously captured.

Within each code structure there are multiple variables viewable to the user. These are described in the following tables.

Table 2: VAR structure variables description

Code Structure

Helios Parameter Description

VAR MEAS_GRID_AC_VOLTAGE Measured instantaneous grid voltage.

MEAS_GRID_CURRENT Measured instantaneous grid current.

MEAS_NTC_MAX Highest temperature reading from the 3 onboard temperature sensors.

PR_CURRENT_AC_NEXT_SAMPLE Grid current command just before being sent to hardware.

VBAT_DC Voltage at the DC terminals (Battery voltage).

BATTERY_CURRENT DC current from the battery (estimated)

PR_CURRENT Output of the Proportional Resonant current controller (before final filter).

GRID_VOLTAGE_RMS_TARGET Instantaneous grid voltage target in islanding mode (dependent on voltage droop).

GRID_FREQUENCY_TARGET Instantaneous grid frequency target in islanding mode (dependent on frequency droop).

REFERENCE_THETA Islanded grid voltage phase reference.

GRID_FREQUENCY Measured frequency of the AC voltage waveform.

VLINK_DC Link capacitor voltage (C225 & C226)

TRANSFORMER_DC Voltage of Transformer T4 output.

PLL_THETA_INTEGER 10-bit value representing grid phase.

VARC_Id_MANUAL, In-phase and orthogonal AC current command if



VARC_Iq_MANUAL VARC_Idq_MANUAL_MODE is set, thus disabling P and Q closed-loop control when in Grid-Tied mode

GRID_VOLTAGE_RMS_SLOW Filtered value for measured RMS grid voltage.

REAL_POWER_SLOW Filtered value for measured real grid power

REACTIVE_POWER_SLOW Filtered value for measured reactive grid power.

APPARENT_POWER_SLOW Filtered value for measured apparent power.

AC_REFERENCE_DC_OFFSET Output of grid current DC cancellation loop.

Table 3: SOFTWARE_INFO structure variables description

Code Structure Helios Parameter Description

SOFTWARE_INFO SOFTWARE.ID Solantro project identifier (typically year/month/day of project start).

VERSION.ID Current firmware revision.

UP_TIME.TIME Time since IXC2 boot.

TIMER Free running ms counter.

INTERUPT_DUTY Percentage of total CPU cycles spent in the interrupt handlers.

Table 4: CAL structure variables description


CAL AC_CURRENT_DC_OFFSET_STATIC_COMP Grid DC current offset calibration value.

Table 5: CONST structure variables description

Code Structure Helios Parameter Description Default

Value

CONST BKBT_DCLINK_ TOLERANCE

Maximum deviation from link voltage target before fault is declared.

45 V

BKBT_DCLINK_TARGET Target voltage for the DC link capacitors. 410 V

VARC_Iq_MANUAL Manual current reference input, must have “STATE.VARC_Idq_MANUAL_MODE”

switched to “ON”. View ‘DPD1128 AC Battery Inverter Functional Description…’ for more

information on VARC MANUAL CONTROL.

0 A

VARC_Id_MANUAL Manual current reference input, must have “STATE.VARC_Idq_MANUAL_MODE”

switched to “ON”. View ‘DPD1128 AC Battery Inverter Functional Description…’ for more

0 A



information on VARC MANUAL CONTROL.

VBAT_MIN Minimum input battery voltage before fault is declared.

40 V

VBAT_MAX Maximum input battery voltage before fault is declared.

60 V

GRID_VOLTAGE_RMS_ TARGET

Inverters target grid voltage in off-grid mode. 240 V

GRID_NOMINAL_ FREQUENCY

Inverters target grid frequency in off-grid mode. 60 Hz

KV_ACTIVEPOWER_ VOLTAGE_SLOPE

Resistive droop coefficient for voltage. Output voltage decrease per watt of output power.

3.91 mV / watt

KW_REACTIVEPOWER_OMEGA_SLOPE

Resistive droop coefficient for frequency. Reference frequency decrease per Var of output

power.

300 uHz/Var

P_REFERENCE Real power target during Grid-Tie Mode. 0 W

Q_REFERENCE Reactive power target during Grid-Tie Mode . O Var

VARC_OVER_CURRENT_THRESHOLD

Current is limited to this value at the output of the PR controller.

6.5 A

MIN_GRID_VRMS Bottom limit for grid voltage fault counter. 211.2 V

MAX_GRID_VRMS Top limit for grid voltage fault counter. 264 V

GRID_FAULT_ THRESHOLD

Amount of consecutive samples of out-of-range grid voltage before inverter turns off the power

train and goes off with fault.

3 Grid Cycles (768)

TRAFO_FAULT_ THRESHOLD

Amount of consecutive samples of out-of-range transformer voltage before inverter turns off the

power train and goes off with fault.

1 Grid Cycle (256)

TEMP_LIMIT Above this limit the inverter will turn off with temperature fault.

80 C

Table 6: STATE structure variables description


STATE FORCE_RESET Forces a hard reset to the IXC-2

SAVE_CAL_TO_FLASH Save any change to a calibration ‘CAL’ variable to flash memory for persistence through IXC2 restarts.

CONTROLLER_MODE Current controller mode of the ACBI, See the ACBI State machine section in document ‘DPD1129 AC Battery

Inverter Firmware Description’ for information on the various states.



REQUEST_MODE Used for changing between ‘GRID-TIED’ and ‘ISLANDED’ (Off-Grid) modes. Sends a mode request, view “STATE.CONTROL_MODE” for the inverter’s

active control-mode.

CONTROL_MODE Indicates the inverters current Gird-Mode state.

INVERTER_START Turns on the inverter powertrain.

INVERTER_RESET Quick turn off of the inverter powertrain. If “STATE.AUTO_RESET_ENABLE” is set to ‘ON’ then

the inverter will restart the powertrain after restart.

ENABLE_SRES, ENABLE_BKBT, and

ENABLE_VARC

Enables only the specified inverter stage, useful for testing individual stages of the ACBI. Only sampled at inverter

startup to determine which stages will run.

VARC_Idq_MANUAL_MODE Enable Manual inputs for Id and Iq, view ‘DPD1128 AC Battery Inverter Functional Description…’ for a

description of Id and Iq.

SRES_RUNNING, BKBT_RUNNING, and

VARC_RUNNING

Specifies which inverter stages are actively running.

DBG_VOLTAGE_DROOP If set to ‘ON’ the inverter will implement a resistive output voltage droop in “ISLANDED” control mode

DBG_FREQUENCY_DROOP If set to ‘ON’ the inverter will implement vary frequency as a function of measured reactive power.

GRID_WITHIN_SPEC Indicates if the voltage at the AC terminals is within specification. See “CONST. MIN_GRID_VRMS” and “CONST.MAX_GRID_VRMS” for a description of

required voltage to meet specifications.

HIGH_TEMP_ERR Indicates if inverter is shut down due to temperature fault.

AUTO_START_ENABLED Allows for automatic inverter start if STATE.CONTROLLER_MODE = = ‘OFF’.

BATT_RELAY_ON State bit set when the battery inrush relay is closed.

GRID_RELAY_ON State bit set when the grid inrush relay is closed.

ENABLE_DC_CURRENT_ CANCELLATION

State bit to control whether to perform DC current cancellation at the AC output.

CANCEL_DC_CURRENT Set by the control loop that actively works to minimize the DC current component in the AC current waveform.

Works in both ‘ISLANDED’ and GRID-TIED’ Control modes. If set, then AC_REFERENCE_DC_OFFSET will be subtracted from the PR controller output before being

sent to the hardware current-loop.

Note: Please keep a record of your test set-up and operating conditions during all testing. In case of board damage, Solantro engineers will require this information for debug.



6 Testing the ACBI Evaluation Platform The following section outlines the test procedures to verify the operation of Solantro’s ACBI. First, testing the grid-tied mode will be explained in Section 6.3, then the testing procedures for off-grid mode will be outlined. Since the Solantro ACBI is a bidirectional inverter, each section will discuss both charge and discharge testing.

In Grid-Tied Mode, the inverter acts as a current source feeding the grid with Real and Reactive power components set with CONST.P_REFERENCE and CONST.Q_REFERENCE.

In Off-Grid Mode, the inverter acts as a voltage-controlled current source with voltage and frequency set by: CONST.GRID_VOLTAGE_RMS_TARGET and CONST.GRID_NOMINAL_FREQUENCY (and perhaps adjusted through droop-control).

To toggle between Grid-Tied Mode and Off-Grid Mode use STATE.REQUEST_MODE and to see which mode the inverter is currently in use STATE.CONTROL_MODE.

For ease of testing utilize the ‘Favorites’ functionality built into Helios. For additional details refer to: DPD1006 Helios User’s Guide.

6.1 LED Status Indicators

The ACBI has three status LEDS. Table 7 below describes their operation and functions.

LED Off On (solid) 1s on/off 0.5s on/off 0.25s on/off 0.125s On/off

Grid (Red)

ACBI unpowered or no AC voltage

ACBI in Grid-Tied Mode

ACBI in Islanded Mode

N /A AC voltage is present and ACBI

off with fault

AC Voltage but ACBI in

Off state

Battery (orange)

ACBI unpowered

DC Voltage within 1 V

below VBAT_MAX

DC Voltage greater than 50% of

allowed range but less than

VBAT_MAX – 1 V

DC Voltage less than 50% of allowed range

but greater than VBAT_MIN + 1 V

DC Voltage within 1 V greater than VBAT_MIN

DC Voltage out of range

Status (green)

ACBI unpowered

N / A Controller running, no faults

N / A ACBI powered but in ‘Off’ state

ACBI fault or ACBI booting

Table 7: LED Status indicator operation

6.2 Putty Telemetry Message Description

During ACBI boot the serial port is used to display bootloader information and messages. After initial boot, the ACBI will output various messages from its Putty COM port describing state changes, error conditions and warnings. A telemetry message is produced every ten seconds in

Figure 6: Putty message description



the following format shown in Figure 6.

6.3 Grid-Tied Mode Testing Once connected to the board with both Helios and PuTTY, the board functionality can be tested. For Grid-Tied testing, a 48 V battery or battery emulator capable of 25 A, a grid connection or an AC Load, and an AC source combination capable of 6.5 Amps peak is required. An example test set-up can be found in Figure 7. See Figure 2 for where to connect the battery and grid on the board.

For all Grid-Tied testing, ACBI output real and reactive power levels are set with CONST.P_REFERENCE (W) and CONST.Q_REFERENCE (VAR) in Helios. Both power references can be either positive or negative with the notation:

Table 8: Power Notation

Power Constant Sign Maximum Value Convention

P_REFERENCE Positive 1000 W Real Power from the battery to the grid (Discharge)

P_REFERENCE Negative -1000 W Real Power from the grid into the battery (Charge)

Q_REFERENCE Positive 1000 Var Supplying Vars (Capacitive)

Q_REFERENCE Negative -1000 Var Absorbing Vars (Inductive)

Different power factors can be achieved by setting a combination of P_REFERENCE and Q_REFERENCE.

The inverter’s apparent power limit of 1000VA is enforced by the firmware in grid-tied mode. The ACBI will prioritize Real Power targets over Reactive Power targets.

Figure 7: Grid Tied test setup



Battery Charging / Discharging in Grid-Tied Mode 6.3.1

If using an AC power supply, set the grid voltage to 240Vrms and the frequency to 60 Hz. Note also that in grid-tied mode, the inverter will not operate without grid presence. At the start of this procedure make sure zero voltage is being applied to both the AC and DC terminals.

If you are using a grid emulator that can not handle back-feeding of power, do NOT set P_REFERENCE to a positive value in any tests unless an AC load is placed in parallel with the emulator to absorb power from the ACBI. Note that, similar to the grid emulator, the DC source must also be capable of sinking current. A load in parallel with DC supply, a battery emulator, or a real battery can be used. Charging:

1. Apply valid grid voltage to the ACBI, this will cause the ACBI board to boot. The inverter will wait until a DC voltage is present before starting the powertrain.

2. Turn ON / apply a DC voltage in the range of 40 -60 V DC. As shipped from the factory, the unit is set to auto-start when it detects a battery is connected.

3. Wait until “STATE.CONTROLLER_MODE” is read as “Running”, or the final characters of the telemetry message is “G RUN”, indicating that the inverter is running in grid-tied mode.

4. Set “CONST.P_REFERENCE” to a negative value between 0 and -1000W to charge the battery / battery emulator at different power levels.

Discharging:

1. If you are using a grid or a grid emulator which can be back-fed, set “CONST.P_REFERENCE” to a positive value between 0 and 1000W to discharge the battery.

Four Quadrant Operation 6.3.2

The following section describes setting CONST.P_REFERENCE and CONST.Q_REFERENCE simultaneously to achieve various power factors.

1. Apply valid grid voltage to the ACBI, this will cause the ACBI board to boot. The inverter will wait until a DC voltage is present before starting the powertrain.

2. Turn ON / apply a DC voltage in the range of 40 -60 V DC. As shipped from the factory, the unit is set to auto-start when it detects a battery is connected.

3. Wait until “STATE.CONTROLLER_MODE” is read as “Running”, or the final characters of the telemetry message is “G RUN”, indicating that the inverter is running in grid-tied mode.

4. Start changing both “P_REFERENCE” and “Q_REFERENCE” to achieve different power factors, examples are included in Table 9:

Table 9: Example power targets

P_REFERENCE Q_REFERENCE Output (W / Var)

+ 1000 0 1000 / 0

- 1000 0 -1000 / 0



0 +1000 0 / 1000

0 -1000 0 / -1000

500 500 500 / 500

500 -500 500 / -500

-500 500 -500 / 500

-500 -500 -500 / -500

1000 1000 1000 / 0

-1000 -1000 -1000 / 0

6.4 Off-Grid Mode Testing For Off-Grid testing, a 48 V Battery or Battery Emulator capable of 25 A is required as well as a load bank rated for 1 kW at 240 V. For optimal Off-Grid Mode testing the load bank should be able to perform load steps of at least 250 W, from 0 – 1000 W. If it is desired to test “battery charging” in Off-Grid Mode, a connection to a PV inverter or other compatible AC source is required, an example test set-up is illustrated in Figure 8.

In Off-Grid mode, the inverter acts as a voltage-controlled current-source with the target voltage and frequency set by the Helios parameters CONST.GRID_VOLTAGE_RMS_TARGET and CONST.GRID_NOMINAL_FREQUENCY. The target frequency defaults to 60 Hz and the target voltage defaults to 240 VRMS. An example for 220 V Off-Grid Mode testing change the target voltage accordingly (it is also recommended to modify the voltage limits):

Table 10: Example 220V Off-Grid Mode voltage settings

Helios Parameter Value

CONST.GRID_VOLTAGE_RMS_TARGET 220 V

CONST.MIN_GRID_VRMS 176 V

CONST.MAX_GRID_VRMS 242 V

To test Off-Grid mode, “STATE.REQUEST_MODE” should be set to “ISLANDED”. As-shipped, the inverter will enter Off-Grid mode automatically if it is powered-up from the battery while there is no grid present at the AC terminals (STATE.AUTO_START_ENABLED is default “ON”).

Firstly, the battery inverter discharging should be tested with just a load via AC bus, without a PV inverter or other AC source connected. To test discharge operation, the load can be varied and the reaction of the ACBI monitored. Then, the PV inverter or AC source output can be connected to the AC bus, along with the AC load and batter inverter output. The AC voltage will depend on the power output of inverter and the power required by the load, and the ACBI will be either charging or discharging, depending on the relative levels of measured grid voltage versus internal voltage reference.



NOTE: IT IS CRITICAL THAT BOTH VOLTAGE AND FREQUENCY DROOP BE ENABLED IF THE AC OUTPUT OF THE ACBI IS TO BE PARALLELED WITH OTHER AC SOURCES USING RESISTIVE DROOP CONTROL.

1. Connect battery/battery emulator, and AC load to the battery inverter

2. Turn ON / apply a DC voltage in the range of 40 -60 V DC

3. Set “STATE.INVERTER_START” to “ON” and wait until “STATE.CONTROLLER_MODE” is read as “Running”

4. The ACBI should by default start in Off-Grid Mode, verify that “STATE.CONTROL_MODE” is read as “ISLANDED”

5. Adjust the load size and observe current and voltage at the AC output

6. Set “STATE.AUTO_START_ENABLED” to “OFF” so the ACBI does not start when the controller mode is set to ‘OFF’. Set “STATE.INVERTER_RESET” to turn off the inverter.

7. Connect output of PV Inverter in parallel with the load. Ensure PV inverter output does not exceed 6.5 Amps peak.

8. Set “STATE.INVERTER_START” to “ON” and wait until “STATE.CONTROLLER_MODE” is read as “Running”

9. Vary the load. To test charging, disconnect the load completely or ensure that its power consumption is less than the PV inverter output.

To test the bidirectional functionality, monitor current and voltage before, during, and after the load is disconnected.

Based on load size and PV inverter output, the ACBI will charge or discharge automatically. Roughly, if the grid voltage is above nominal, the battery will charge, assisting in voltage regulation, and if the grid voltage sags below nominal, the battery will discharge to support the grid.

Figure 8: Islanded Mode with external AC source attached



Revision history Rev. Author Description Date

1 Trevor Hadden Initial release 2017-09-20

2 Thomas Corkum Edit 2019-06-12

2.1 B Bacque + T Corkum Small fixes for release 2019-06-14

Solantro Semiconductor Corp Address: 146 Colonnade Rd

Suite 200 Ottawa, On, Canada K2E 7Y1

Phone: (613) 274-0440 Fax: (613) 482-4748 Email: [email protected] Web: www.solantro.com

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