Hi Chris
These are the answers:
1. Are you sure your parameters are correct? It is a very large flux and a very small Ls.
Using the Isc equation:
Isc= Flux(V.s) / Ls (H) = 0.019/0.000165= 115.15 A
Isc= (Flux(V/Hz) / 2*pi) / Ls (H) = (0.12/2*pi) / 0.000165= 115.74 A
I agree, it is a very large flux in reference with the stator inductance; unfortunately the manufacturer does not count with the parameters data (Rs, Ls and PMflux). I obtain these data from the back-EMF signal of the motor, the figures below show the voltage measured with the oscilloscope.
Figure 1. Phase to Phase back-EMF signal at 100 RPM
Figure 2. Phase to Phase back-EMF signal at 300 RPM
I obtain the inductance from a LCR meter with a frequency of 200Hz (which is greater that the maximum electrical frequency of the motor, Electrical Frequency= Maximum Speed*Pole Pairs / 60= 900*10/60= 150Hz) the result is Ls= 330uH and Rs= 324mOhms phase to phase. I don’t know if the machine is salient poles or non-salient poles, I am using the average of the measurements with the LCR meter.
If they are close to correct, as stated you certainly need to PWM faster. Have you looked at the outputs of your competitor's controller to see what PWM rate they use? Can you post a scope of their current waveform in the same conditions?
I don’t have a sample from other controller, we have choosen this motor about its low cost and InstaSpin for the FAST feature for a sensoless control scheme.
Do you think that I am measuring the parameters in a wrong way?
What do you recommend to do?