Got out the stuff today to the old FS before I go.

Got some more flux core wire and did a bit of welding from a "sudden stop".

Hey there. Yet another future EV-er your project has inspired. I just bought myself a Baker 12" motor almost exactly like the one you sold off recently. Look Familiar? Square drive and all. I'm hoping to swap it into an Audi Coupe GT. I've got a bit of an electrical background, so I am attempting to make my own 'home-brew' motor controller to run this beast. While I intend to use the car for commuting and require 30mile range and 65mph+ speed, I too am doing mine on 'the cheap'. Cost so far (haven't even gotten the car yet) is $291.75, and includes the motor, and everything I need for 2 PWM controllers (assuming they work).

Thanks for documenting your project so thoroughly! Perhaps when I have something to show, I'll start my own thread and do the same.

Can you please create another thread or post to a link for your inspiration on the PWM? I found a couple schematics and bought all the stuff I need just haven't assembled it yet. But it'd be good if I understood the theory behind it a bit. For now I'm still trying to play with learning pic programming. This was going to be for an electric motorcycle job but now I'm thinking more about converting the front of an MR2 to electric and integrating my PWM controller with my megasquirt in someway to control when to turn the ICE on/off and blah. It will probably never happen but at least I'm assembling all the pieces.

Hi BigMouse

Yup, that motor end cap looks very familiar! If you do go ahead with the project, I hope you'll post a thread.

Building a PWM controller is way over my head. A contactor controller perhaps... What kind of controller specs are you aiming for?

I'm not exactly an electrical engineer, but from my research, this is my plan for the controller:

I ordered a few of these chips:
The one on top.

I plan to build that per the schematic in the manual that includes the power supply, and use it to drive an IGBT.

Here's an example of an IGBT being used in an AC Variable frequency drive application. Basically, if you just take one branch from that (with the PWM circuit as the "controller"), you have what I'm going for.

With a small PWM circuit driving an IGBT, the capacity of the controller is dependant on the capacity of the IGBT, since that, and that alone is carrying the load of the motor (in theory). I ordered some 400A 1200V IGBT's on eBay. If I run two of them in parallel, I should have a capacity of 800A. The specs on the IGBT's are such that they will be able to handle the 16khz PWM frequency with no problem. And if not, they frequency is selectable with that chip. Really looks to be pretty simple. I hope it ends up being as simple in reality as it is in theory.

That MR2 project sounds very cool. I'm running megasquirt on my 1990 Audi Coupe Quattro with a turbo engine swap in it. Such an awesome little box that is.

Have you discussed this on the EVDL? Someone got the regulars riled up recently discussing home-brew PWM controllers. Something about children building treehouses...

Definitely keep us posted here or in another thread.

Nope, wasn't me. I haven't joined that list yet. I can't stand the old style mailing lists where everything gets forwarded to everybody. An online forum like this one is much preferred for me.

Agreed - I'd much prefer a web-based EVDL.

But there are some incredibly smart, helpful & articulate people on there which make it worth following (if you can stand the volume of messages, which is another issue).

BigMouse: pregrommed PWM chips, that's cheap too. Much cheaper than me trying to figure out microprocessor programming myself... though maybe less robust.

Wow, looking through my gmail looks like it was last October since I last played with all this... I can't find any of my links either (which isn't helpful since I have a box of electrical bits based on those sites). I remember I had a couple sites, one for a converter to generate 200-300VAC and another for an inverter to output 3 phase with PWM. I was basically trying to build a variable frequency drive and use a throttle input and somehow decide what revs that should be and how much acceleration, etc. But like I said I have no idea what I'm talking about and at the time I even wanted to build my own motors in the wheels, I calculated I needed 0-16k or 0-20k rpms or so, which isn't really possible for a high HP motor.

I have too many projects....