something above 40 kHz maybe even 100, 200 kHz and it would push the noise out of the range of your ears. You could set the primary chop frequency really really high in your controller. It would be similar to a 3 phase motor controller, but respond to pulse inputs like a stepper and have 2 phases out. You would be looking at something that converts a digital amplitude value signal into an analog voltage output (a DA converter) of maybe at least 8 bits to create a 'smooth' out for each coil that is fed into a circuit that can deliver sufficient current for each coil.

The way around it would be to build a hybrid analog stepper controller that can microstep, but without chopping DC up. Even microstepping doesn't exactly get rid of this since the intermediate steps are created by high-speed sushi chefs cutting the supply voltage into itty bitty fishy pieces. What you're hearing are the squeals and high-frequency chopping that occurs in stepper controllers. Hi all! here is the video of my setup noise, any advice on what's the possible reason or how to get rid of it would be appreciated.

Stellarium arduino