MCF8316A: MCF8316A

carl troili

Part Number: MCF8316A

Hi,

I have two questions regarding this motor. Does it support regenearative braking ie returning energy to the dc bus to lower the speed. I am aware of that any overvoltage situation have to be handled.

Our application will speed up and down the motor freqently and we would like to save power and avoid heating the motor.

Is there a maximum rotational speed that is possible. We would like to achieve up to 75000 rpm.

Regards

Carl Troili

over 2 years ago

0 Vishnu Balaraj over 2 years ago

TI__Mastermind 24405 points

Hi Carl,

Thanks for posting your question in MD forum. MCF8316A supports regenerative braking. When Anti voltage surge (AVS) function is disabled, supply voltage will overshoot during the motor deceleration. In order to protect the device, ensure the voltage on VM and phase pins does not exceed abs max voltage of 40V.

I'm not sure about the number of pole pairs of your motor. MCF8316A can support up to 1300 Hz (Electrical speed). Use below equation to convert electrical speed (Hz) to mechanical speed (rpm).

Motor speed (rpm) = 60*electrical speed (Hz)/pole pairs

Regards,

Vishnu

0 carl troili over 2 years ago

Prodigy 50 points

Hi Vishnu. that means that for a two pole motor it limits the speed to roughly 40 000 rpm ie about half of what I need. What limits the speed in this IC ?

0 carl troili over 2 years ago in reply to Vishnu Balaraj

Prodigy 50 points

Hi Vishnu, is this 1300 Hz a hard limit or what causes that limit. Given that we the minimum poles ie 2 that gives us a maximum rpm of 40000 which is a bit low.

0 Matt Hein over 2 years ago in reply to carl troili

TI__Mastermind 21805 points

Hi Carl,

Vishnu will get back to you tomorrow!

Thanks,

Matt

0 Vishnu Balaraj over 2 years ago in reply to carl troili

TI__Mastermind 24405 points

Hi Carl,

For a two pole motor, maximum speed will be 60*1300/1 = 78000 rpm. Maximum speed is limited by the bandwidth of FOC speed and torque loop.

Regards,

Vishnu

0 Matt Hein over 2 years ago in reply to Vishnu Balaraj

TI__Mastermind 21805 points

Hi Carl,

Most of the time we see that ultra-high speed motors try to use trapezoidal control rather than FOC to achieve a higher speed. Is your motor designed for trap control or FOC control?

Thanks,

Matt

0 Vishnu Balaraj over 2 years ago in reply to Matt Hein

TI__Mastermind 24405 points

I will close this for now, since I haven't heard a response back. If you want a follow-up, please feel free to reply to this thread or create a new thread.

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MCF8316A: MCF8316A