I have a dc motor with 12V, 13.5A and power output of 106W. I already made a circuit but every time I try to simulate it won't work. The frequency I want of the 555 is 24khz and a duty cycle from 0% to 100%. I need to have the most efficient components but affordable to produce low power dissipation across the PWM circuit. What do you think is the problem with my circuit ?

 

First impression the IRFZ44 is characterized, largely, at Vgs = 10V, but your
divider does not achieve ~4V. Also available 555 output current due to R3
very limited. I would eliminate R3/R4, and put a series R from 555 output
to IRFZ44 gate. Start with 100 ohms. Point of this is to partially decouple
MOSFET gate C from output of 555 timer to limit excessive chip current
and to minimize transients due to wiring L at gate of MOSFET. You will
have to experiment with this value.

At 24 Khz driving the MOSFET gate right out of 555 timer without a gate
driver for the MOSFET questionable. You want lots of current to minimize
the time MOSFET in linear region dissipating lost of power.

Regards, Dana

 

First impression the IRFZ44 is characterized, largely, at Vgs = 10V, but your
divider does not achieve ~4V. Also available 555 output current due to R3
very limited. I would eliminate R3/R4, and put a series R from 555 output
to IRFZ44 gate. Start with 100 ohms. Point of this is to partially decouple
MOSFET gate C from output of 555 timer to limit excessive chip current
and to minimize transients due to wiring L at gate of MOSFET. You will
have to experiment with this value.

At 24 Khz driving the MOSFET gate right out of 555 timer without a gate
driver for the MOSFET questionable. You want lots of current to minimize
the time MOSFET in linear region dissipating lost of power.

Regards, Dana

Thanks for the help Dana, I will try it