Help regarding H briges.....

[koolguy]

Hello everyone,


I have IRF 540 and IRF 9540 MOSFET and i want to drive motors of 24V and 10-12amps, so it require a H-Bridges.....
something like this.....so please give your view will this MOSFET is fine...??

Note:- now i am just using 12V supply after it will be 24V

Please post a schematic for that....

 

[ronv]

If it is 12 amps continuous they are a little marginal. They would dissipate about 23 watts at 12 amps. Your heat sink looks like about 5C rise per watt so they might be about 125C.
The second problem is when you are using 24 volts the gate to source voltage on the P Channel will be over the 20 volt spec.
It is often better to use all N Channel and a high side driver IC.

PS. That doesn't look like a 12 amp motor. Is it just for test?

 

[koolguy]

Hi,

PS. That doesn't look like a 12 amp motor. Is it just for test?

yes...

but please post circuit of it, when using 12V supply..

 

[Reloadron]

This should be what you are looking for.

Ron

 

[ericgibbs]

Hi,


yes...

but please post circuit of it, when using 12V supply..

hi Ritesh,
Did you look at the 74LS06 and 07 IC's which I suggested yesterday on Chat.

You require voltage level shifter if you are using PMOS FET's in the upper section of the H Bridge when using +12v Or +24v supply and a 0/+5V control voltage output from your PIC.

The 06/07 IC's work upto a maximum open collector of 30V.

 

[koolguy]

Hi again,


I have tried this circuit it was working fine ( i have tested up to 1.5A) in this case i have used 12V supply but now i want to change it to 24V.
so, for that i think the circuit will be different.

 

[ericgibbs]

hi Ritesh,
Did you look at the 74LS06 and 07 IC's which I suggested yesterday on Chat.

You NEED level shifters from the PIC to the MOS 12/24V

 

[koolguy]

Did you look at the 74LS06 and 07 IC's which I suggested yesterday on Chat.

But some one suggest me not to use it don't know why..
I am not sure what do....?
can u please post a schematic.....?

 

[ericgibbs]

But some one suggest me not to use it don't know why..
I am not sure what do....?
can u please post a schematic.....?

Who suggested not to use them and why.??

 

[koolguy]

Who suggested not to use them and why.??

Just leave it you tell me how to add this chip with 24V?
(I think i was not sure..)

 

[ericgibbs]

Just leave it you tell me how to add this chip with 24V?
(I think i was not sure..)

hi,
Look at this option , using 74LS06 and 07 IC's as level shifters.

 

[ronv]

updated

 

[ronv]

Eric,
I think that will violate the 20 volt gate to source spec. on the FETs.

 

[ericgibbs]

Eric,
I think that will violate the 20 volt gate to source spec. on the FETs.

hi Ron,
Thanks for the 20V point, as at this time I am not sure which power MOS the OP will choose.

When he lets me know I will tweak the values to suit.
He asked for an IC solution to level shifting rather than using transistors, why .????

E

 

[koolguy]

hi Ron,
Thanks for the 20V point, as at this time I am not sure which power MOS the OP will choose.

When he lets me know I will tweak the values to suit.
He asked for an IC solution to level shifting rather than using transistors, why .????

E

Hi again,

I am using IRF9540 AND IRF540..and i am ready to use transistor.
In your schematic i like that 4 diodes near motor!!

 

[ericgibbs]

Hi again,

I am using IRF9540 AND IRF540..and i am ready to use transistor.
In your schematic i like that 4 diodes near motor!!

Checking the datasheets you have posted, the +/-20Vgs limit does apply. It will be necessary to limit the Vgs on the MOSFET's to less than this value.

Check the web for existing designs.
Google: 24V MOSFET h bridge circuit
http://hades.mech.northwestern.edu/index.php/Driving_a_high_current_DC_Motor_using_an_H-bridge

 

[koolguy]

In this schematic you are using pull up resistance at P-MOS upper side i think it will decrease the Speed due to Capacitance in MOSFET gate ..

 

[koolguy]

Will this schematic will work fine.......?
and what should best PWM freq ...??

 

[4pyros]

Will this schematic will work fine.......?
and what should best PWM freq ...??

You said;

I am using IRF9540 AND IRF540..and i am ready to use transistor.

This circuit dose not use transistors.

 

[4pyros]

what should best PWM freq

Some ware around 10 to 15 Khz, depends mostly on the motor and some on the application. You may have to experiment to find the best freq.