FCM 8201 - Over voltage protection of motor driver

Electric Motors and Controllers
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Lagoethe
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FCM 8201 - Over voltage protection of motor driver

Post by Lagoethe » 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.

victorcastro89
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Re: FCM 8201 - Over voltage protection of motor driver

Post by victorcastro89 » Feb 27, 2012 12:12 pm

Hello, you succeeded in using the FCM8201?
i tried stand- alone and spi mode but don't worked.

trike20
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Re: FCM 8201 - Over voltage protection of motor driver

Post by trike20 » 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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Lagoethe
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Re: FCM 8201 - Over voltage protection of motor driver

Post by Lagoethe » 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)
There are very few people on this earth that are totally free. I'm not free but I'm working on it.

e-doc
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Re: FCM 8201 - Over voltage protection of motor driver

Post by e-doc » Jul 11, 2012 4:03 pm

Has anybody of you a FCM 8201 controller successfully running?

e-doc
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Re: FCM 8201 - Over voltage protection of motor driver

Post by e-doc » Jul 14, 2012 9:17 am

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

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