XM3 Inverter Module Drawing Current while off

Tom

I'm testing a new XM3 inverter unit and trying to run the sample code with the XM3 inverter software. I apply DC voltage to the +/- inputs, and I expect to measure a AC output. Right now there is no 3 phase load connected, just a scope to monitor the output, open circuit voltage.

But I think something may be wrong with the module. It is drawing current from the DC input, 10A sustained current even at a low 5V DC input. I have not tried increasing the voltage much beyond that since this seems to indicate a problem. It draws current when all the logic switches are set to off. It also draws current whether the module is powered on or powered off.

Also, with no DC input connected, I still measure around 2.5 V at the input bus. Is this leaking from the control board power supply? This is enough voltage where I can actually run the unit and get an AC output, with no connections on the DC input.

Does this unit have a bad FET? Why is it drawing so much input current while not running?

I tried re-programming the device following the guide but get the same results.

This is with no input DC, but still measure output switching somehow.

Forum_Moderator

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Tom

Nevermind, embarrassing mistake. The cover plate was turned over, swapping the + and - symbols. Since U, V, W, +, and - all look the same when mirrored, it's hard to tell that the cover was reversed.

AustinC

Hi Tom,

I'm glad you found the solution to your question. To provide some additional information, it is common to have an output voltage similar to the first image you posted even with no bus voltage connected. This is due to the over-current (DESAT) circuits providing a small voltage across the power devices when the gate drivers turn on. This is the expected operation and no need for concern.

Best Regards,

Austin C.

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.