I am designing a new controller using the FCM 8201 chip which seem perfect fo our applicationshttp://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.
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
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