hello,
I'm using this circuit to control a dc motor speed using a PWM from a microcontroller.
details:
using n-channel enhancement mosfet , 400V , 30A ratings.
1 KHZ pwm signal connected to the mosfet gate.
30A flywheel diode
dc motor ratings : 160V , 20A .
I first tried this with VGS value of 5volts (connected the pwm directly from micro to mosfet gate) , but the mosfet got burned (drain and source were short circuited) .
the mosfet datasheet mentions that the VGS value could be up to 30V , so I used an op-amp to amplify the pwm signal to a max of 15v and connected that to mosfet gate , the motor worked fine for about quarter the scale , then the mosfet got burned again and I lost control of motor speed (rotated full speed regardless of VGS)
also the motor is not loaded , so current can't have reached more than 30A.
can any one help me with that?
I'm using this circuit to control a dc motor speed using a PWM from a microcontroller.
details:
using n-channel enhancement mosfet , 400V , 30A ratings.
1 KHZ pwm signal connected to the mosfet gate.
30A flywheel diode
dc motor ratings : 160V , 20A .
I first tried this with VGS value of 5volts (connected the pwm directly from micro to mosfet gate) , but the mosfet got burned (drain and source were short circuited) .
the mosfet datasheet mentions that the VGS value could be up to 30V , so I used an op-amp to amplify the pwm signal to a max of 15v and connected that to mosfet gate , the motor worked fine for about quarter the scale , then the mosfet got burned again and I lost control of motor speed (rotated full speed regardless of VGS)
also the motor is not loaded , so current can't have reached more than 30A.
can any one help me with that?