Part Number:DRV10970EVM
I am running the DRV10970 with a Maxon 339267 BLDC, with an input voltage of 12V. I am able to spin the motor without issue in trapezoidal mode, however in the desired sinusoidal mode I am encountering two issues. I have the Rcs resistor set to 33k, which should keep the current limit to 900ma
1) At low PWM the motor is "skipping", successfully making 3/4 of a rotation before slowing and then resuming.
Blue = Current through single winding
Green = FG pin
2) At higher PWM the motor spins continuously, however the waveform, which starts out as the third-order harmonic shown in the datasheet then turns into something much more trapezoidal.
Blue = Current through single winding
Green = FG pin
Is it possible for the output to be sinusoidal for the entire range? I understand that trapesoidal could be needed to at higher RPM's however, this should not be an issue at low RPM. I also increased the current limit, by reducing the value of Rcs, and did not see any improvement.
The DRV10975 was also tested and it was able to maintain sinusoidal current draw for the entire RPM range tested.