TMS320F28069F: InstaSpin - Torque is really low at low speeds

Dave Reagan

Intellectual 810 points

Part Number: TMS320F28069F

Tool/software:

Hello,

I'm working on a project using InstaSpin FOC, based heavily on the DRV8301-HC-EVM Rev D Eval kit.

It's for an Electric Dental Handpiece, so I need the speed to go from 100 rpm to 40,000 rpm.

The speed isn't an issue currently, but the torque at the low end is almost nonexistent.

At 100 rpm to 500 rpm, all I have to do is touch the motor shaft and it stops.

At the high end, I can't stop it with bare hands at all. I'd have to use needle-nose pliers.

I thought electric motors were supposed to have MORE torque at low speeds.

What's going on here?

Thanks,

Dave

over 1 year ago

0 Yanming Luo over 1 year ago

TI__Guru** 117160 points

That's normal. The test you did is not right. You should use a dyno or braker to add load for test, not by your hand. The output torque is dependent on the torque current of the output of the speed regulator.

0 Dave Reagan over 1 year ago

Intellectual 810 points

Hi Yanming,

Is there some way to increase the current at low speeds? It's very low.

Thanks,

Dave

+1 Yanming Luo over 1 year ago in reply to Dave Reagan

TI__Guru** 117160 points

You can try to increase the maximum current to enable a high torque output and tune the speed controller to improve the response.

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TMS320F28069F: InstaSpin - Torque is really low at low speeds