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Hi everyone, I’m a bit confused about the currents in my FOC-controlled PMSM AC motor.
At maximum speed and with a load connected, I measured the following currents using a current probe:
The current in quadrature is not "constant" because my motor has two rollers that press alternately against the load... so we can say that the current (and therefore the torque) is variable, but that shouldn't be the point of my query.
1) If I set Iq,max = 20A via firmware .. will Iphase,max then be 20A? Or are these two independent values?
From my measurements, it seems the answer is "yes, the maximum values are the same" … but I’d like to hear the opinion of someone who knows more about the subject. To confirm this, in the event of a motor stall, one of the three phases has reached exactly the Iq,max value (the others have stopped earlier at different values, as is to be expected)
2) So, if it is true that Iq,max = Iphase,max … does this hold for all other values? Such as the average, the RMS and the minimum values? … for example, for the minimum value, the equality no longer holds because Iq cannot be less than 0, whereas (as you can see from my measurements) Iphase,min is negativ
At maximum speed and with a load connected, I measured the following currents using a current probe:
- Idc,bus = 1,3 A
- Iphase,rms = 2 A
- Iphase,span = [-3,7 .. 3,9] A
- Iq,span = [1 .. 3,9] A (I measured this value in the firmware)
The current in quadrature is not "constant" because my motor has two rollers that press alternately against the load... so we can say that the current (and therefore the torque) is variable, but that shouldn't be the point of my query.
1) If I set Iq,max = 20A via firmware .. will Iphase,max then be 20A? Or are these two independent values?
From my measurements, it seems the answer is "yes, the maximum values are the same" … but I’d like to hear the opinion of someone who knows more about the subject. To confirm this, in the event of a motor stall, one of the three phases has reached exactly the Iq,max value (the others have stopped earlier at different values, as is to be expected)
2) So, if it is true that Iq,max = Iphase,max … does this hold for all other values? Such as the average, the RMS and the minimum values? … for example, for the minimum value, the equality no longer holds because Iq cannot be less than 0, whereas (as you can see from my measurements) Iphase,min is negativ
