One really annoying thing that I have is the fact that so far, we can't get a OBC to actually run on the bench, without being re-fitted in the car. I've supplied the two 12v supplies to the top pcb, and 240vac to the input of the OBC, but the OBC sits there doing nothing. In particular, I see that the relay inside the doghouse does not even close when testing on the Bench. I added wires across D301 and ran them up above the top pcb to a LED and a 330R resistor
so I could have an indicator when voltage was applied to the relay. On the bench, I could see the Three big electrolytic caps charge to 347v but the relay never closed. This was not a problem at the time, because the IGBT section was also not running, so the only current that the 2x 4.7R resistors had to deal with was the electrolytics, and once they charged, there was not much current flowing through the resistors. Once I fitted the OBC back in the car, and the charge cable plugged in, you can hear the contactors click, the fan comes on, and within a second the LED that I added shows the doghouse relay closes. I guess this means that what drives this relay is not just a dumb timer circuit, but is reliant on the controller on the top pcb to be happy with everything before the relay gets activated. The Things that are currently not being connected to the OBC when its on the bench are the 360V Traction battery OUTPUT, 12v aux OUTPUT, and CANBUS lines. I would think that not having the 12v AUX OUTPUT connected would be a problem with the DC-DC Section running, but would not think this would keep the top OBC Section from running, as long as the 2x 12v supplies power the top pcb. I think it comes down to the OBC not being happy and running with no 360v traction battery load, since the output current and voltage sens values would all be wrong. The other problem would be not having proper CANBUS communications from the EV-ECU may prevent the charger from running.
Now that I have a running OBC in my test bed car, I will try purposely cutting one of the CANBUS lines to see if the OBC still starts charging. I think it will detect AC, the contactors will close, the fan will come on, the charging light on the dash will come on, but this will only last for a few seconds and then all will shut off due to a timeout error with no CANBUS Communications.
<EDIT>: I purposely cut one of the CANBUS Lines to see what the OBC would do. When I plug in the charge cable, I hear the fan start, showing AC was detected, but after a few seconds this stops and no charging even starts.
The LED that I added to show if the doghouse relay is activated, never lights up. This means that during the AC Detection phase, current is running through the 2x 4.7R resistors, but due to a CANBUS Connumications timeout, everything stops before the 2x 4.7R resistors even get bypassed, and the relay is never activated, and the IGBT's never run. So at the end of the day, we can't do full bench testing unless we can simulate the CANBUS Communications or simulate that the controller on the top PCB is happy with everything so it activates charrging.
Last edited by skylogger
on Thu Sep 13, 2018 8:47 pm, edited 1 time in total.