Tronic H-bridge

[eloverphx]

Just wanted to move this discussion to the new site as I would like to see this forum to continue and for the scene to get larger.

Anyways, I have my AMC and my H-bridge built and working with small motors. When I try to use my wiper motors (2005 Chevy truck wiper motor) they pull to much current and fry my FET's and the motor won't turn. I'm thinking maybe do as one person was saying and tying both side of the H-bridge together to get more current capabilities but waiting on more of his testing results. Also I was thinking what if I could add A/C capacitors before the motor to help with the in-rush current to get the motors started? I'm hoping there is some one out here that may have some engineering background that could confirm if this would work and possibly what size cap would be needed. I'm guessing the start up current is about 10-15a at 12v DC. My motors are around 0.9-1.1 ohms of resistance sitting on the bench.
Thanks for the hard work on the new x-sim software and I hope to start building my motion sim and help test and assist people as they make their journey to this exciting project!!

Erik.

[motiondave]

I did a search and found that 2005 Chevy Trucks (big ute) should be 12 volt. But just to add some confusion, the trucks were released with low and high output alternators. This shouldn't make a difference to the wipers you have though.
Still test and get the wipers earth isolated as Bob says. I nearly blew a JRK from an un-earth-isolated wiper.

[eloverphx]

Thanks to you both I will try to check on those items today when I get home and give you the results. I do know the motors are 12 volt motors but will check on the isolation.

[eloverphx]

Here are some pictures that I took. Can't seem to attach a video using tapatalk on my iPhone. But here are some pictures of my AMC, h-bridge, and wiper motor. I took the motor apart and isolated the ground and still no luck. It made my FETS get hot instantly and the motor doesn't move. Getting frustrated. I just want to get my motors working so I can start building my sim. And I can't afford to buy JRK's

Ok also I just tested my other wiper motor and haven't isolated or done anything to it yet. I hooked up high speed and same result. Then I tried low speed and it struggled to move the motor but it did so for a min in both directions. I didn't let it go too long with no heatsinks on and the FETS got very hot. This motor has more resistance sitting on the bench then does my other one. It has almost 2 ohms on low speed and only around 1 ohm on high speed. Also I thought I would mention I am using a 12v 300w dc power supply to run the motor. It runs them fine when I hook each motor to the power supply and run them. I don't know exactly what amperage they are since my meter only does 10amps I don't want to blow up the fluke. Anyways. What do you all think. I'm running low on positive thoughts at this point.

[motiondave]

Ok, before you explode, and I know how you feel, if you have successfully earth isolated the motors so the case does not allow any negative power to run the motors, you are ahead one step.
Next step, test the motors with power only and NOT related top the h-bridge. Just power the motors and find the faster speed. If the motors move with no issues, then you are also on your way.

As for the h-bridge, I cannot help with that as I was lazy and bought JRKS. I have not the patience to build my own. And by the way, I have had to replace 3 JRKS from my own stupidity, so a cost factor was involved but sure worth it. I just didn't tell the wife.
Perhaps send a PM to tronic and ask him about the h-bridge.
Cheers, David.

[eloverphx]

http://www.youtube.com/watch?v=eyZGD49wvAQ&feature=youtube_gdata_player


Thank you for your help. I'm so close * I ran the motor off a car battery and had better luck. Looks like the power supply dipped too much on the voltage and the current was spiking and causing most of the problems. Ultimately did some damage to something on half the h-bridge. Have to look into it tomorrow. The side that is sorta working I'm getting great forward direction but reverse is super slow and really not functional. I read the voltage with no load in reverse and get 11.89v. With the motor connected it dips to 5v-6v rather that sticking to 12v. Not sure what is going on but getting soooooo close. I'll upload a video maybe tomorrow.

[RafBR]

Are you using IRFZ44N or IRLZ44N mosfeet? The right one is the IRLZ44N!!!

[tronicgr]

http://www.youtube.com/watch?v=eyZGD49wvAQ&feature=youtube_gdata_player

What kind of LED you a using on the h-bridge??? It looks kinda TOO MUCH BRIGHT!!!

Did you try test the motor without that LED connected (you know remove the jumper for the leds)!!!!!

[RafBR]

Just wanted to move this discussion to the new site as I would like to see this forum to continue and for the scene to get larger.

Very good idea!

[eloverphx]

http://www.youtube.com/watch?v=eyZGD49wvAQ&feature=youtube_gdata_player

What kind of LED you a using on the h-bridge??? It looks kinda TOO MUCH BRIGHT!!!

Did you try test the motor without that LED connected (you know remove the jumper for the leds)!!!!!

Tronic, I got the green led from digikey. I think it's just a super bright. They are a bit obnoxious but they do the job.

I finally have figured all my problems out on the h-bridge. I was about to give up but finally prevailed. Hopefully someone will learn from this craziness.
My very first problem was the wrong chips as j went with the non- logic model (about 3 months ago I got the right ones. The logical ones.)
My next problem was bad solder joints and cracks on the traces that I couldn't see. Had to use a meter to find them.
Next was my power supply wasn't stony enough to run the motors through the h-bridge although it ran them fine without the h-bridge. Attaching to a car battery fixed the high current low voltage situation that was burning up my FETs so instantly.
A little after that I would move my FETs around to see if I could move my problem from one direction to the other and cause more problems by breaking the solder joints on the screw terminals.
And last but not least. Chinese FETs. Grrrrrrrrrr. I think I should have paid more rather than less on e-bay. I had a handful of FETs that would not close completely do I would get slow rotations and some the legs would just simply break off when I barely would start to bend them or had sever cracks in them that would cause me problems with intermittent connection.
Anyways. It's finally working complete with heatsinks and a fan.
Now to save enough money to start my frame. And I need to finish drawing it up. That is another post of mine that I have started.
Good day and thank you all for your help along this journey I am on!