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Motor Power Calculation (Watt)

Associate III


I am working on a motor control project that is to be driven battery-powered. This means that the DC current has to be monitored in order to avoid overloading the battery. 
I have made a Control Loop which takes in a DC Current reference as input and adjust the torque. The Current Calcuation is derived of the power calculation for the dq-framework.
P = (id*vd+iq*vq) * Conversion_Factor ... 
(I am using the standard power calculation provided by ST)
My Problem is that the Internal Power Calculation doesn't match with the external power measurements from the power-supply. 

Take a look at the following signals:

Internal Power CalculationInternal Power Calculation
Internally measured power, W (red)

Power Supply MeasurementPower Supply Measurement
Externally measured power, Pin (orange)

The main problem is that (Pin) isn't held stable (flat at ~160W). What could the reason be for the difference between the internally measured power (W) and the externally measured (W)?

Best Regards Nikolaj


Motor: BLDC with Hall sensors

Motor Control WorkBench: Version: 6.2.1


Inverter Board: STEVAL-SPIN3201

Algorithm: FOC

Control Mode: DC Link Current Control (Custom)