Observation:
- The main contactor has it's contacts welded together. 0.1 ohms all of the time. I removed it from the circuit. But the interesting part is that the solenoid still makes noise - click - and you can feel it when it turns on and off. But the resistance is 0.1 ohms all of the time. I will likely keep the contactor with an NFG label on it. I'll cut it open later and take pictures, or maybe a teardown video. It's useless as a contactor ...
Re-arrange the wiring.
Code:
+125v Battery Pack +--S1 switch S2---- R1 10 Ohm R2---- AC BUS+
| |
+125v battery pack R1 (contactor) R2
+125v pack ground --------- AC controller ground
+ for pack, S1 and S2 are terminals on switch, R1 and R2 are terminals on pre-charge resistor
So now we are connected as Paul has suggested. I replaced a ring terminal on the precharge resistor to make sure there is good, solid contact. And I have added a meter on the DC bus to show when it is charged. This visual feedback was added since I can't trust the contactor to open!
I've add to my test procedure. I now turn on the meter at the beginning of the test set, verify that the DC bus is low, then turn on the DC breaker. I observe a precharge (it only takes a second or two) then I turn on the 12V to the controller and it does another 5 seconds of precharge, then the main contactor pulls in. More time, hopefully less equipment damage!
I went over the logs and it appears that perhaps 500 was almost too high - file 153 for those of you following along at home. The first sample is 512 at line 5. And the sample drops to 1 at line 13, just 8 samples later. It starts to oscillate a bit, from 33 - 97 counts. Since Paul said it was OK to have -60 or -50 for noise, I'll assume that 33 - 97 is OK for noise.
So I'll just use 500 * 8 = 4000 for Kp. Then I'll go through Ki at 1,2,4,8 ... until it .. umm ... not sure when I stop! I would normally stop increasing Ki when you get a nicely underdamped response (curve drops quickly, then approaches the target of 0 with no overshoot). Maybe I'll just capture and graph, then post them for Paul to review!
File 190 - Kp 4000 Ki 0. Looks good, like file 153. So file 191 will be at Kp 4000 and Ki 1. This looks weird. A bunch of negative numbers. Try Ki 2. Just as weird, but different.
Umm .. but Paul .. help?