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My Power Controller

6884 Views 23 Replies 5 Participants Last post by  kennybobby
Finished Soldering 6 Power Controller boards last night. :)

In my Solectria E10, I am planning on having 4 parallel groups of 20 Leaf modules in series (150V @ 65Ah per group), and thus I need a way to pre-charge, connect, and disconnect them to/from the main vehicle power bus.

That is the main function of my Power Controller board:
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The main problem with paralleling large battery packs together, is when one cell fails shorted. You now have lots of available power from the other good packs, attempting to charge the (now lower voltage) pack with the short in it.

This can cause thermal runaway (fire). :eek:

So the power controller monitors the stack and pack voltage (individual cell voltages, via the BMS), and current into and out of the pack.

If it detects an anomaly* it will disconnect that pack from the main bus.

Pack over/under volt
Pack over/under temperature
Pack over/under charge (Amp Hours)
Cell over/under volt
Current over/imbalance (compared to other power controllers)

It can also send a CAN message and/or +12V signal to force a controller into limp home mode, and/or stop a battery charger.

Designed to bolt directly* on to the Nissan Leaf Contactor.
Standalone, or CAN controlled mode.
Solid state pre-charger.
Pre-charge resistor temperature sensor.
Two contactor drivers, with economizers.
Limp home / end charge signal.
Isolated voltage sense of the A and B side.
External current sensor.
Low power sleep mode.
4-bit unit ID (for CAN address / Standalone mode).
5V I2C with interrupt line for future expansion. ;)

Power cables are bolted and torqued to the contactor first, then the power controller board is bolted on top.

Next, I need to build up the Current Sensor boards, and write some firmware, and test.

Then they go in the truck. :D

Here is a video:
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This is a great idea and project that you have built-- to be able to take an entire parallel group of cells off-line in the event of some anomaly. Thanks for sharing the video and progress.

Have you reverse engineered the leaf BMS such that you can tap in to the cell monitoring and balancing, or is your microcontroller going to handle all those functions?
Any testing or progress to report on your power controller?
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