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Member

Join Date: Nov 2006
Posts: 6

Can I Use an H Bridge For Two Motors?

11/15/2006 9:10 PM

hello

Can anyone tell me if I can use a mosfet h bridge for two motors?

I don't have any problem with reduced speed.

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Guru
Engineering Fields - Electrical Engineering - New Member

Join Date: Sep 2006
Location: El Lago, Texas, USA
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Good Answers: 65
#1

Re: Can I Use an H Bridge For Two Motors?

11/16/2006 10:14 AM

I'd connect the motors in parallel, that way they will each get the full voltage from your h-bridge. Just be sure you can supply that much current. The mosfets will see the two motors as a single load, there shouldn't be any problem. If the two motors are not identical, and you're using a PWM type motor controller, there will be some issues in controlling the speed of one versus the other. But for simple on/off control, I don't see any problem.

Of course, I'm an optimist.

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Anonymous Poster
#2

Re: Can I Use an H Bridge For Two Motors?

11/17/2006 8:14 AM

what kind of motors? What kind of mosfets? I tinkered with a project like this but found that finding powerful mosfets that didn't cost a lot was pretty difficult...

Is there a reason you want one controller for two motors? Does your schematic contain a typical h-bridge or something specific for two motor control?

Like the last post mentioned, unless they're perfectly balanced one will have less rotational resistance or inertia and the other one will always lag behind in terms of speed. if you need them turning synchronously or balanced in any way then a different setup, possibly with feedback might be necessary.

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Guru
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#3
In reply to #2

Re: Can I Use an H Bridge For Two Motors?

11/17/2006 9:41 AM

You can get 80A, 60V mosfets, like the IRF1010E, for a few bucks.

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Member

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#5
In reply to #3

Re: Can I Use an H Bridge For Two Motors?

11/17/2006 10:13 AM

thanks ppl

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Anonymous Poster
#4

Re: Can I Use an H Bridge For Two Motors?

11/17/2006 10:12 AM

My company was selling an intergrated MOSFET dual H-bridge IC for an audio "digital amplifier". We had thought that these parts could be used as stepper-motor drivers, but we never bothered to investigate. STMicroelectronics is selling the line.

http://www.st.com/stonline/products/literature/ds/9821/sta508.pdf

Depending on your specific requirements, this could work. Be advised these were intended as audio devices and designed to operates with impedances ranging from 2-16ohms, so I'm not sure of the impact of going "mo-pow". These devices also have over-current / thermal protection, and a warning-flag pin.

wndrtch

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Anonymous Poster
#6

Re: Can I Use an H Bridge For Two Motors?

11/17/2006 9:01 PM

why dont you just go to Yaskawa or Lenze.... they both make drives that can be set up in a master/follower arrangement with either electronic"lockstep" or one as a gear ratio of the other with pretty much any combination of said gear ratio from follower to master available(yaskawa's is available to eight places on either side....) and no i dont work for either of them or sell their stuff..

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Member

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Posts: 6
#7
In reply to #6

Re: Can I Use an H Bridge For Two Motors?

11/18/2006 7:15 AM

i want to drive a car wiper motor of 12 volts and i am using TO 220 packege mosfet

i doin rite or wrong

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Guru
Engineering Fields - Electrical Engineering - New Member

Join Date: Sep 2006
Location: El Lago, Texas, USA
Posts: 2639
Good Answers: 65
#8
In reply to #7

Re: Can I Use an H Bridge For Two Motors?

11/20/2006 9:46 AM

You need to know how much current is going to the motor. You need to know the maximum current rating for your mosfet. You need to know the ON resistance of your mosfet - this times the current will give you the power your mosfet has to dissipate. From that you will need to calculate the temperature ris of the mosfet so you can provide the correct sized heatsink.

Or, you can just hook up the mosfet and see how hot it gets. If it's too hot to touch, then you need a bigger heatsink. Keep increasing the size of the heatsink until it's cool enough to keep your finger on it. If you connect the source of the mosfet to ground (chassis ground) and the drain to the motor, with the other side of the motor connected to +12V, AND if your mosfet has the tab (body) connected to the source, then you can bolt the mosfet onto the body of the car, and use that as your heatsink. Don't forget to put a fuse in series with the motor. Provide a resistor to ground on the gate so that stray voltages don't turn the motor on accidentally.

Good luck.

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Power-User
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Location: Mexicali, BC, México
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#10
In reply to #8

Re: Can I Use an H Bridge For Two Motors?

11/22/2006 12:37 PM

Take care what bhankiii said!!!.

I control some power motor with power mosfet transistors... and belive me that we invest a lot of money on mosfet just because we did not took care what Bhakii said.

Just in our sample and experience:

Our mosfet transistor was able to drain 24A... we calculate to run the electric motor with 10A... o surprice!!.... allways the mosfet burn out. So we knew that each time we run this motor it consume 8 times the current we calculate at the starting point.

So please take in mind this.

Delmar

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Member

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Posts: 6
#9

Re: Can I Use an H Bridge For Two Motors?

11/20/2006 9:04 PM

thanks

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Member

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#11
In reply to #9

Re: Can I Use an H Bridge For Two Motors?

11/25/2006 11:56 PM

hey

sir plz check my link in which i hav posted the ckt which i hav used as a hbridge wiht the specifications

and plz tell me where should i make changes

mosfet here is TO 220

http://ajbisht.googlepages.com/

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Users who posted comments:

ajbisht (4); Alhuey23 (1); Anonymous Poster (3); bhankiii (3)

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