TMS320F28069: Instaspin at low RMP

Part Number:TMS320F28069

Team, 

My customer is having trouble in getting the AC induction motor to start and run smoothly at low RPMs (<500) using Instaspin dev board.  There is a lot of torque ripple.  

They don’t know if they have something set wrong, or if the chip is just not capable of driving the motor that slowly.

Thanks

Viktorija