DRV8711: Optimizing DRV8711

Part Number: DRV8711

We are using the DRV8711-EVM to drive a motor that is fairly inductive (200 step/rev, 6.5mH, 2.1 ohms). For accuracy, we need to use microstepping of 64, and for speed, we need pps =100kHz. Our power supply is 28V, though we could use a 48V supply. We set the torque register to get 1A through the motor. As we try to increase the speed, our current waveform deviates from  a sinusoid and becomes triangular. We are using the forced fast decay mode. Increasing the supply from 28 to 48V helps, but doesn't quite get us to where we need to be. TBLANK = 1.5us, TOFF = 5us, ISGAIN=40.

Any insights as to how we could improve things?

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