H-Bridge circuit

[buteman]

Hi all,
I have a problem with the electonic window winder on my car. and the garage wants GBP148 for a replacement unit plus labour costs. i believe a simple mosfet circuit would do the job and have designed a circuit which I think will work.
I have attached a diagram. Please have a look and tell me what you think.

 

[4pyros]

What is controlling the up and down limits? Andy

 

[buteman]

At the moment my information is that the motor has built in protection for over current conditions which would occur at each end of travel. In truth I would be surprised if this is so.
This circuit is a preliminary one which I will try out first with a low power motor.
i intend to use a micro-controller with the final board. ( a cut-down version of my arduino Uno ) If this circuit functions as I hope I can add 2 extra jfets which would be used to turn on the p-channel mosfets to provide braking if needed. Also a low value resistor to allow the micro to detect stall current conditions and respond as needed.

 

[Grossel]

Hi. I se no reasons why this shouldn't work.

However, be aware that if Input1 and Input2 is high at the same time, then you get a short. But since this is for a car window system, I bet the switches is made so it isn't possible to have both inputs high.

 

[buteman]

Thanks Grossel,
I was aware that the short circuit condition could happen and indeed the switches are arranged so it would not happen normally.
Fortunately the circuit from which I will be taking the power from is also fused and I will be adding a low value resistor which would limit the maximum current anyway to less than the maximum the mosfets can handle.

 

[ronv]

How much current does your motor draw?

 

[buteman]

Not sure yet. To get at it and the control circuit I need to strip the door down to the point where it is just a shell.
Wonderful design here! I only have an open area of land to work in and this "summer" so far has been rain most days.
The whole mechanism is lots of wire under tension and to remove it means detaching the glass and propping it up somehow.
All I know is the fuse for this and other parts is 25 amp and what I can see of the wire it would only manage maybe 10 amp max.
The mosfets would be max 17 amp types.