I have been reading here for a while and I'm simply impressed by the projects shown here.
So today I want to make my first humble contribution.
1,5 years ago I came up with the idea of converting a regular ICE car electric (how unusual
). I decided it would have to be an AC-motor since most of the complicated parts of spinning it are done in software plus it offers the best effiency. I also found out that standard ACIMs are really cheap and can be overpowered for short periods. Unfortunatly I also found out that controllers are really expensive.
Being an electrical engineer I decided to give it a try. My first inverter consisted of some BUZ50 mosfets and controlling circuitry around it. It basically worked but of course would only drive a 1:10 model of a car
So I scaled up and have now got this:
It uses a 1200V 90A IGBT, IGBT drivers, a hardware PWM-module and a PC. It basically spins the motor at whichever frequency you set it to and it even uses the space-vector modulation scheme to achieve the highest possible amplitude. I know 90A isn't much but it's a start.
At the top you see the voltage with the little space vector "dent" and the current at the bottom.
There is one problem though: it is all open loop and it uses a PC. Also the PWM resolution is just 8 bits.
My plan is to put the controller program on a little µC which offers 16-bit pwms. For closing the control loop I want to start out with a speed sensor and thereby control the slip of the ACIM in some clever way that is still to be figured out. Since I have never seen any serious motor controller without current sensors and vector control I might have to implement that as well. There are closed loop sensors already on the IGBT-module but their output somehow didn't seem to linearly follow the amplitude of the current.
When all is finished I want to document it like the well known Open Source Motor Controller.
So... do you think this is a promising project worth continuing? And if yes, any suggestions?
Looking forward for replies