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Old 08-31-2015, 11:09 PM   #1924 (permalink)
thingstodo
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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?
Attached Files
File Type: txt 190.txt (4.2 KB, 21 views)
File Type: xls 190.xls (88.5 KB, 12 views)
File Type: txt 191.txt (4.2 KB, 14 views)
File Type: xls 191.xls (88.5 KB, 15 views)
File Type: txt 192.txt (4.2 KB, 18 views)
File Type: xls 192.xls (96.0 KB, 50 views)
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MPaulHolmes (08-31-2015)