Can I emulate BLDC motor torque control with a speed controller?
The DRV10975 already is a BLDC sensorless speed controller. You should avoid this product, if you want to control the torque. What you need is a current controller, PWM controlled bridge and then a feedback information about the current and speed. You have to limit the torque if the motor reaches max. speed. This is a classic cascaded loop:







simulate this circuit &ndash; Schematic created using CircuitLab

Speed setpoint is the max. speed. The block diagram is simplified due to the screen size, it has also some factor multiplications and what's important, the speed controller outputs the reference torque [Nm] that goes trough a limiter - this becomes your torque setpoint.

The encoder can be replaced by sensorless hardware and algorithm. More suitable IC is DRV8302 or similar, where you get the current and adding comparators, you can do the sensorless stuf.