Wheels-a-spinning II
Hard to believe that it has been almost exactly 2 years since the wheels spun under electric drive. In my blog and video of May 2014 I described and showed how I connected the Siemens and DMOC to the car and had strapped up all the batteries in the wooden crates they were received in. Using a bench-top contactor system, a throttle body and a GEVCU I was able with the to get the wheels spinning, just to prove all the hardware worked. Now 2 years later I finally have all the components assembled in the car and all of the assembly has been completed in the engine compartment. I got the DMOC bolted in and connected to the buss bar and Siemens. I installed the GEVCU on top of the DMOC. In my last video I had made a measurement to test that the GEVCU would fit there. It really was the best place to mount it considering all the wiring connections. All those connections are now complete. I also came up with a mount for the throttle body. Using some angle aluminum pieces I fabricated a mount that would bolt to the side of the DMOC, using the screws that hold the DMOC cover as fastening points. I also came up with a fixture to hold the throttle cable. That throttle body from NetGain is real piece of bling. Very nicely anodized and is a dual Hall effect sensor. The only issue I have with the wiring is with the fabricated wiring harness I got for the GEVCU from EVTV. It is very nicely made, all the wires are color coded and labeled. The issue is that I only need about 2/3 of the wires in my build. There are 35 wires on that harness so I have about 20 wires that have no place to go. I might just coil them up and put them in an enclosure so I could use them in the future if I need any of the unused signals.
I finally got all the wiring and battery connections done so that I could start charging the full battery pack. Of course that did not go as planned. When I installed the new Siemens EVSE and turned it on for the first time it came up in failure mode. I called Siemens and they had me try all kinds of resets but nothing worked. So they are going to replace the unit. I did not really need the unit to charge the car. I really wanted it so I could test out the J1772 interface to the Brusa to make sure that would work with public charging. To charge the battery pack what I did was removed the J1772 cable and plug from my old EVSE and put a plug on the other end so it could plug into the 240V outlet I had installed for the Siemens. The Brusa charger did not start at first. I found through the monitor program for the Brusa that I had forgot to connect a thermisitor for the battery temperature measurement. Once I added that the Bursa started right up and I was able to set the parameters in the ChargeStar program. The batteries only had about 7 AH of energy so for the pack that corresponds to about 2.5KW. The pack is 25KW so at 3.3KW charge rate per hour that means it will take just over 6 hours to charge the pack.
Before fully charging the pack I wanted to make sure all the subsystems worked, from the DC/DC converter, DMOC, Siemens, GEVCU, BMS and instrument cluster and LEVID driver. When I first connected the high voltage through the contactor box that was controlled by the GEVCU the DC/DC converter did not initialize. The Delphi requires a CAN message to be sent with the target charge voltage before the unit will output any current. I thought that was in the GEVCU code, but apparently it is not. To get the DC/DC converter running I programmed another GEVCU board with the Delphi program. That worked to get the Delphi running and charging the 12V battery. The next test was to spin the Siemens motor. That would test the motor, DMOC, high voltage wiring and GEVCU. I calibrated the throttle and connected the gas pedal to the throttle cable. Pressing down on the pedal I expected to hear the nice sweet sound of the Siemens spinning up. Unfortunately all I heard was a rough sound and felt a lot of vibration. Even with full throttle the DMOC only drew 10 Amps. At that torque request it should have put out 100 or more amps. Something was definitely wrong. I brought up the embedded website on the GEVCU. The overview page showed all green indicators. Next I brought up the dashboard page. When I pressed the throttle, the throttle indicator ramped, the requested torque gauge ramped but the tachometer showed no rotation, even though the motor was making sounds. I next brought up the ccShell program that is used to program the DMOC. It has a viewer screen on which any parameter of the DMOC can be displayed. The one of interest was the IR2Hertz parameter, which is the motor RPM value. When I pressed on the throttle pedal the IR2Hertz value jumped around, first showing 22 rpm and then -24 rpm. To further check the system I mounted a tire on one of the rear wheels. Just powering the DMOC with 12V I brought up the ccShell program and watched the IR2Hertz value as I manually rotated the wheel. The IR2Hertz value showed the same wrong values from before. Unfortunately this is an indication the motor encoder signal is corrupted in some way or the DMOC has failed. I can't believe the DMOC could have failed, it has only be used a half dozen times and not really for very long or for high power output. The encoder hardware in the Siemens motor is most likely not bad either. Both the motor and DMOC have been tested together several time, the last time just a few months ago to test the GEVCU in the CINCH enclosure with the new wiring harness. Everything worked well then. The only thing linking them is the encoder cable. I removed the cable to test the continuity, but first I examined the connector shells and jacks on the cable and the DMOC and Siemens. What I found was on the Siemens jack one of the pins was bent over and pushed in. It turns out the bent pin is one of the encoder pins. I had to remove the connector jack from the Siemens to access the pin to push in back in and straighten enough so it would go into the connector. I was able to straighten the pin enough for the cable connector to go on. After remounting the connector jack and connecting the cable I tested the RPM reading by manually rotating the rear wheel again. Now I get a good reading of RPM. The bent pin was causing one of the encoder signals to be lost. Once I put the DMOC back together and got all the other connections reinstalled I started up the system and connected the high voltage. Finally a nice smooth spinning of the Siemens! I put the transmission in gear and spun the rear wheels! Now all that's left is to assemble the dashboard and install the new carpeting and seats and it will be ready for a test drive.
A video of all this fun can be found here.
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