Hello,
I am testing the DRV8308EVM board with a small brushless DC vacuum pump. The motor has 3 hall effect sensors, and I am currently using the driver in "XOR of all three sensors" mode for commutation. The pump motor seemed to be working fine in PWM mode at first. The issue started if I set the duty cycle too low the motor would stall. This is understandable since the motor is unable to overcome the torque needed to start. However if I increase the duty cycle again the motor will stay stalled even at 100% duty cycle. I then toggled the motor enable pin off and on and the motor starts up just fine. Is there a special start-up mode that the motor uses to do a soft start? is there a ways to have the motor driver automatically respond to a stalled rotor?
When I was testing the motor stalling one of the times, one of the power fets started smoking and the power supply's over-current protection started going off. The FET is now not working at all. I am using the EVM board as is and the board should current limit based on the ISENSE resister. The rotor was not stalled for a very long time (maybe 8 seconds) which leads me to think that the current limiting did not work. Does the current limiting capability of the DRV8308 not work when the rotor is stalled. If so is there anything you can suggest to prevent the power FETs from burning in the future. The motor driver we need should be able to survive a stall.
Any help is appreciated,
Ilia
