H bridge Solder-less Output Stage

[clow57]

Hi I am trying to build a motor controller for a small electric utility vehicle I am building. See pics and video.



[youtube]5r6EV0Xsa7I[/youtube]



The project is being documented at Hackaday https://hackaday.io/project/4997-light-electric-utility-vehicle

My main goal is to keep things as simple, cheap and repairable as possible, because I would like this project to be reproducible by local people where I work in South Sudan. Currently I am using a sabertooth 2x60 as the controller, but I'm running into the current limit, and I only have two of four motors installed. They are brushed unite 650w @24v motors 550 rpm with built in planetary gearbox. I am looking to upgrade to something more like the OSMC open source motor controller at 160a continuous. I want to parallel two motors per controller and have two controllers. Does anyone have experience or thoughts on the osmc? My initial thought was I don't really like the idea of no heat sink on the fets. I started thinking through it and I had a number of scraps of 50x50x3mm aluminum angle and came up with an idea for an 16fet output stage that wouldn't need soldering except for the gate connection. I thought I would check here to get some feedback. Please tell me if I am way off. I tried running the positive and ground rails as close together as possible based on the info from the Lebowski output stage. Here are some renderings:


The general idea is that the heat sinks act as busbars connected to drain on the fets. There would be bolts where there are holes in the rendering to keep a good connection between fets and the heatsink. The source leg would be sandwiched between two aluminum plates bolted together. The only soldering would be for the gate which would be in a twisted pair like lebowski shows on his output. No soldering to the heat sink.



I would love any feedback to see if I should actually pursue this, or why this is stupid. Obviously I have not drawn in any caps, but I would also love to have any suggestions that way as well.

Thanks

 

[dnmun]

you should clarify by a re edit, 'would be source'.

the idea is to not use soldering because there is no electric power for a soldering iron? how about a small pencil gas soldering iron? or prebuilt kits assembled where there is electricity?

there so little clearance between the legs in comparison to the size of the metal angle, i would expect just normal flexing would end up shorting the source drain legs or the gate leg so the occupants would be subject to failures they could not begin to comprehend imo.

maybe build them in a location where there is power and have a spare available to swap out or would anything not nailed down be lost?

 

[clow57]

Thanks for the catch I have changed it. The lack of soldering is to make it easier to assemble and especially repair. I haven't tried it, but I would imagine trying to solder a to-220 fet to a big 3mm heat sink would be rather difficult without damaging it. This way someone with limitted soldering skills can still build the output stage, and fix it easily if they blow a fet.