Other Parts Discussed in Thread: DRV8301, MOTORWARE
I inherited a TI Instaspin motorware based project that runs on a custom board using a DRV8301. It turns a 24V BLDC motor that is embedded in a water pump. The software was based on motorware v16 proj_lab11a, so much so my predecessor didn't even bother to create a new instance and just edited the original V16 project. The issue with the controller is that at a speed just below nominal rated RPM of 3450 the motor spins up out of control.
The test setup is the water pump/motor in water with a flow meter and I'm using a multimeter to measure the RMS voltage across two of the motor leads. I can control the pump speed with a pot on the custom board and monitor the controller via the emulation probe and debugger. With 36V supplied to the board I can control the motor up to about 3200 rpm as reported by the debugger. This puts about 24.5V RMS across the two phases of the motor. Any higher and the motor takes off at high speed. I can tell the motor is spinning fast as the flow rate jumps way up, and the voltage across the two phases jumps to 27.5V RMS. The interesting part is the controller thinks the motor is running at the commanded RPM of about 3300. Also interesting is if I increase the supply voltage the controller is able to stay in controller at a faster speed. Still spins out of controller at some point, but better. Also, note I'm able to control the pump/motor smoothly through it's whole range with controller board from another manufacturer.
It looks like my predecessor was in the process debugging the issue as he has commented out the speed PI controller calls. Not sure what that was to accomplish. I started moving the project over to V18 in hopes something in there would fix the issue, but I've since gotten feedback that it probably wouldn't.
Any suggestions or thoughts would be appreciated.
Thanks, John
