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Incorrect Batt Current Readings in FOC but not in BLDC

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vadicus
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Incorrect Batt Current Readings in FOC but not in BLDC

This issue was mentioned in a few other threads together with other issues but I would like to have a thread dedicated specifically to the battery current readings in FOC mode. Hopefully, we can get to the bottom of it.

I am running my custom HW described here: https://vesc-project.com/node/1477

However, a few people reported similar observations on other HW including the original VESC HW such as 75/300.

I am running current control mode with FOC detected values for the motor. Here is what I am seeing.

At 5-10% throttle on unloaded motor, the battery current is reported about right (3-4A). If I go 100% throttle on an unloaded motor, it will go full speed and the current will be reported at around 11-12A while my ampermeter that I use as a reference reads only 6A or so. So, on an unloaded motor, the battery current readings are higher by at least 80% from actual consumption.

On a loaded motor, I get somewhat incorrect readings at 10-20% of the throttle. When I go full throttle, the battery readings on VESC are more or less close to the ampermeter readings (19-20A).

When I switch to BLDC, the battery readings on VESC are close to the ampermeter readings pretty much at any throttle and/or load. 

I also noticed, that tweaking flux linkage value changes the amp readings for the battery.

Any ideas/suggestions, how to make it read battery current correctly in FOC mode?