I've made some good progress over the last week. The majority of the low voltage wiring has been completed and I was able to power everything up today and spin the wheels!
It's still only on a 30V power supply as I've got the battery pack to sort out. I was able to turn on via the key and the forward/reverse switch and throttle worked perfectly. The precharge and contactor circuits seemed to work fine too.
The bad news is that I still have an intermittent problem with the inverter gate drivers/IGBTs. I had this before when testing on a bench but I decided to get it all wired in properly before investigating further in case it was a wiring problem with my test setup.
This is the process I went through today:
- I turned the ignition on, and then to the momentary start position after a couple of seconds. The power supply hit the current limit (20A). (no throttle input and neither forward or reverse selected)
- I knew the problem before had been related to the gate drivers/IGBTs so I unplugged the lead between the driver board and the first IGBT. The whole system then turns on fine and forward or reverse can be selected.
- I then plugged this lead back in. Everything turned on but the PSU hit the current limit as soon as I selected either forward or reverse. (no throttle input). If I then flick back to 'neutral' it stays at the current limit but if I turn it off and back on again it will be fine until I then select forward or reverse again.
- Unplugging the other driver-IGBT leads doesn't help at all so it seems related to the first IGBT lead that I unplugged.
- Eventually, after a few minutes of turning it on and off and fiddling with these leads I got it to the point where I could select forward or reverse without it hitting the current limit but upon applying some throttle the PSU would cut in and out and the motor would turn rather jerkily.
- It then started working perfectly, spun the wheel up fairly quickly without hitting the PSU current limit
- After taking some videos and enjoying seeing the wheels spinning for the first time it then stopped working again. This time there was no PSU current limit but the motor would only jerk back and forth however much throttle I applied (as if one phase was not working?).
- It then went back to hitting the current limit every time forward or reverse was selected
My feeling is that it is something to do with the gate driver or connections on the combi board. The intermittent nature makes me think it's not a parameter issue or a something broken in the power electronics. I had a few suggestions back when I was testing it on the bench that I still haven't tried but if anyone has any ideas let me know.
I have some videos of it working that I'll try to upload later.