skylogger wrote: The DMM I'm using is a UNI-T CAT III I bought from Altronics rated to 1000V
The 0.8 on the DIODE test that I am measuring is when the + of the meter is connected to the - if the Electrolytics, and the - of the meter is connected to the + of the BIG 3X Electrolytics.
Yes, that's what is expected. These are the two back diodes across the main IGBTs. I was still trying to work out why there was nothing on the 3 large electros. But you say there is 345-348 V there now, so that's fine.
I'd still like to see the 0.4 V from the PFC IGBTs. You should see this on the other side of the PFC diode, e.g. J21 to J19.
In trying to check the 2 x 4.7 resistors in the doghouse, ... I am getting a reading of 9.7R so the EMI Filter is probably adding the 0.3R
More likely your multimeter leads add 0.3 Ω to the reading. At 14 ARMS, the I²R loss would be 59 W.
If I apply MAINs AC Input, and check the voltage at these same points, I see a voltage drop of 1.57vac
Interesting. I think it could be out-of-phase inductive drop, but it might indicate resistance. There would be a spike of current when the capacitors charge up near the peak of each mains half-cycle.
At this same time, I have a clamp AMP meter on the LIVE AC line in, and it is only measuring 0.09amps Since it's not drawing much current,
This would make me think the 1.57vac is mainly being droped across the 2x 4.7R Resistors and the relay is still open?
As above, I just don't know. It depends on the leakage inductance of the EMI filter inductors.
The situation on the voltage across the 3x electrolytics being 348vdc and then gradually dropping, may be due to my MAINS source. My house is powered by Solar power only, so my Mains is actually from an inverter. This may result in some weird readings when there is a surge trying to charge the electrolytics, and they charge up to 348vdc but now that I've been brave enough to let it run a few minutes, it only drops to 345.5vdc and stays constantly there for the rest of the testing session.
Well sleuthed. I think that explains it exactly. So the front end seems to be working as expected, except that there is no PFC boost.
So if I'm probing around the 1K gate pull down resistors, what other point would I use as the reference point. would this be the + or - of the 3x electrolytics depending on if I was checking the high side or low side?
Use the negative side of the big electros, and measure only the gates for what you think are the lower IGBTs. It won't hurt to measure the upper IGBT gates, but if they are switching, then they will have the ~340 VDC square wave superimposed on them. The reference for the upper IGBTs will be their outputs; the IGBTs act on the base to emitter voltage, and the upper IGBTs are emitter followers. It might make sense to measure the outputs with respect to big electro minus first, to see if there is any activity. As mentioned earlier, I don't expect to see switching pulses without a CAN message to start charging, and that likely requires either the charger in the car, or some service aid that we haven't discovered yet. In the Elcon/TC chargers, you could insert a jumper and get artificial switching pulses for testing. I think we need a fair bit of Kenny-work before we get to that stage
In short, there probably isn't much more that you can do till then.
Would it be worth unplugging the transformers, and in place of their primaries, temporarily put a 10w 10k dummy resistor.
I don't think so. Also, 9 watts in a 10 W resistor with no heatsink will get extremely hot.
I might have to put the charger back in the car and connect the communications cable to it so that the controller PCB is happy before it will generate the gate drive signals. It might run for a few seconds before the error is detected and shuts down.
Yeah. A slow test cycle, to be sure. It will be great to figure out some bench testing techniques.