H-bridge problem

[shahzad-h]

Hi to all

I am working on h-bridge project my h-bridge cotains four N-channel mosfet part no(IRFP460) and TL494 IC as PWM generator the h-bridge works well on small Dc motor but not work on 3A dc motor the 3A dc motor runs only in one direction and not in other in one direction rotation upper single mosfet becomes heatup and other three remains cool also when pwm outputs r disconnected the motor runs automatically with slow speed and it stops when the gate terminals of mosfet r shorted together
plz help.............

Thanks

 

[audioguru]

You forgot to attach (upload) your schematic.

 

[shahzad-h]

HI audioguru

here is the schematic

 

[audioguru]

Your problem is that the upper Mosfets are used as source-followers. Then their gate voltage needs to be boosted to +10V higher than the supply voltage to turn on properly.
H-bridge ICs that are designed to drive Mosfets have the voltage booster (called bootstrap circuit) built-in.

Maybe yor circuit will work if you used P-channel Mosfets at the top and change the phase of their drive.

 

[ClydeCrashKop]

Some motors, like a starter motor are only meant to turn one way. They have the commutator advanced for best power in that direction.

 

[shahzad-h]

Thanks audioguru

circuit is working properly with p-channel

Thanks

 

[Hero999]

Some motors, like a starter motor are only meant to turn one way. They have the commutator advanced for best power in that direction.

Sometimes it's only because the field coils are wound in series with the armature so when you reverse the power the field is reversed, the net result being rotation in the same direction.