FCM 8201 - Over voltage protection of motor driver

Electric Motors and Controllers

FCM 8201 - Over voltage protection of motor driver

Postby Lagoethe » Thu Jan 12, 2012 5:23 am

Hello everybody,

I am designing a new controller using the FCM 8201 chip which seem perfect fo our applications
http://www.fairchildsemi.com/an/AN/AN-8201.pdf

My problems come quite late in the application note: Page 14

"Braking and instantaneous speed/load change during operation of BLDC motors may generate back-EMF voltage and feed it back to input voltage of motor drive, bringing about a sharp rise in input voltage. If the sharp voltage rise is not appropriately checked, it may burn down the power transistor and the whole driver circuit"

Isn't there also a risk to damage the battery?

"Basic application circuit for motor drive OV protection is shown in figure 25. With the divider resistor [...]. Once the voltage of the VSENSE pins exceeds 4.5V, the OV protection function of motor drive triggers."

Assume we have 48V Battery.
Vbatmax= 60V is it a clever choice?
V_SENSE x (R1+R2) = Vbatmax x R2
V_SENSE =4.5, Vbatmax=60V then I choose R1 I find R2.
Solved
But..
What would happen with a fully charged battery or nearly discharged one. Could anything bad happen?

Thanks for your help

PS: Pretty soon I'll have a web site, explaining the whole design of the controller.

Have a nice day
There are very few people on this earth that are totally free. I'm not free but I'm working on it.
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Re: FCM 8201 - Over voltage protection of motor driver

Postby victorcastro89 » Mon Feb 27, 2012 12:12 pm

Hello, you succeeded in using the FCM8201?
i tried stand- alone and spi mode but don't worked.
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Re: FCM 8201 - Over voltage protection of motor driver

Postby trike20 » Sun Mar 04, 2012 10:21 pm

I am also doing a breadboard with the FCM 8201. I should have it ready for smoke in 2 weeks.
Going to use stand alone open loop for testing.
Cheers,
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Re: FCM 8201 - Over voltage protection of motor driver

Postby Lagoethe » Wed Mar 07, 2012 2:26 am

I'm waiting for last components.
They should be home next week.
Have you got some schematics of your boards/bread boards?

Have a nice day (I can post mine in eagle if someone want)
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Re: FCM 8201 - Over voltage protection of motor driver

Postby e-doc » Wed Jul 11, 2012 4:03 pm

Has anybody of you a FCM 8201 controller successfully running?
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Re: FCM 8201 - Over voltage protection of motor driver

Postby e-doc » Sat Jul 14, 2012 9:17 am

Lagoethe, you have mail (PM)... :wink:
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