Hey guys.
We designed a driver for BLDC motors recently and we replace ours with the destroyed one. We were searching for why the original driver would damaged and we have just one reasonable answer for this.These drivers may work 1 month or some years,so the thing damaging these drivers is something rare.
Below is the schematic of the h bridge controlling the motor.We guess that a spike on the power supply cause the p channel mosfets burn.
The n channel gate and the base signal comes from a microcontroller with 5 v regulated supply.So if the 24v drops to 18volts or less the micro controller is still sending signal to the mosfets.The n channel gate-source voltage is enough to keep it in saturation area with low Rds(on) but the pmos source gate voltage drop around 3 volts and much more Rds(on)and burns.
So we need a circuit to break the 24v in case of low voltage detection and it must work as fast as it can.What do you suggest?
We designed a driver for BLDC motors recently and we replace ours with the destroyed one. We were searching for why the original driver would damaged and we have just one reasonable answer for this.These drivers may work 1 month or some years,so the thing damaging these drivers is something rare.
Below is the schematic of the h bridge controlling the motor.We guess that a spike on the power supply cause the p channel mosfets burn.
The n channel gate and the base signal comes from a microcontroller with 5 v regulated supply.So if the 24v drops to 18volts or less the micro controller is still sending signal to the mosfets.The n channel gate-source voltage is enough to keep it in saturation area with low Rds(on) but the pmos source gate voltage drop around 3 volts and much more Rds(on)and burns.
So we need a circuit to break the 24v in case of low voltage detection and it must work as fast as it can.What do you suggest?
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