I am trying to control the speed of the motor by pwm the gate of a mosfet. the circuitry that I am using works but it keeps frying the mosfet.
can some one help me?
http://www.mikeamick.com/misc/MC2100_rev_engrd.pdf

 

That can happen if it is hooked up wrong.

Can you show us how you hooked it up?

John

 

if it works for a while, then fries, is the mosfet rated high enough?

 

Do you have a protection diode? I fried one of my MOSFETs that way... lesson learned.

 

What is the motor voltage?
Motor Current?
What drives the FET?
What is the PWM frequency?
Is the FET bolted to a heatsink?

 

Post your circuit and the others as Mike ML mentioned.

 

Also, did you size the mosfet for the inrush current or the running current? Motors pull a high initial current when they are building their magnetic field on startup. I've seen it burn up solid state relays, so it's something to keep in mind.

 

 

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I need some help to figure out why i keep frying a mosfet. belove you will find a striped out motor control circuitry that i want to use to control the speed of a brushed motor. the motor rating is as follow: Brushed motor rated 120vac 12amps 1400w 50/60hz. The circuit start working at a low pwm pulse( analogWrite(pinNum, 20) ). I works slow but it is a litle noicy. When i increase the pwm pulse it snaps the mosfet and the motor start working at full speed and it gets wery hot in a short time. I had run the motor with a full motor controller circuitry that has it is own controller chip and the motor runs fine. I can pwm that circuitry with my controller at any pwm pulse. I want to pwm the mosfet gate and be able to control the speed of my motor. below are both circuitris the full motor control and the striped out version. I believe that some how i need to limit the current that the motor is getting because when i use the full circuitry the motor does not get hot and it runs smooth and i can controll the speed. I am not very electronic involved person but I am a quick learner.

 

What is the type number of mosfet that you used?

 

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