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I'm seeing what seems like an unusual quirk with the Zombieverter controlling the contractors when restarting after ignition off. I've run a few tests and grabbed a few short videos. Hoping someone can help explain what I'm seeing!


Setup:
Zombieverter V1.10A, 4x12V batteries in series for HV (~49V, Udcsw set to 35V for pre-charge), GS450H transmission and inverter, 12V battery for LV, 3 x gigavac contactors (Pre-Charge, Neg, Pos), 100R 100W pre-charge resistor, 500A DC fuse, ISA shunt, 3 x contactor state LED's (left on screen = pre-charge, middle = HV positive, right = HV negative), control panel (from left: Zombieverter power, ignition on, start, brake, fwd/rev)


What's happening:
I can power up the system from scratch at any time and things work as expected, contactor switching sequence, gear select, transmission spin. If I switch ignition off (leaving constant power to Zombieverter) and switch ignition back on before the HV decays to lower than Udcsw, the system will power back up as expected.

However, if I let the HV decay to below Udcsw and try to switch ignition back on, pre-charge and negative contactors come on but positive never does. You can see in the video's the voltage momentarily climbs but then drops to only a few volts so Udcsw is never reached. Then all contactors open.

Simply power cycling the Zombieverter gets the system back running ok, and interestingly, using HV Request instead to bring on HV in similar tests works every time. Another observation is that when I move the meters positive lead to the output post of the pre-charge contactor, the voltage does jump to the 49V pack voltage (before the pre-charge resistor), but is only 1V to 2V after the pre-charge resistor.

I wondered if there's a simple electrical explanation like back voltage from the inverter cap, or the pre-charge resistor rating. But as everything works with the HV Request pin and not the ignition on signal, this made me think there could be something in the code or how the inverter might be brought into the system via the code as that looks like the only logical difference between the two start up methods?


Videos:
This first video simply shows the system being started up from scratch. The red LED's show the contactor sequence, meter shows the HV at the inverter input. Transmission is put into forward and run for a few seconds. At the end, the system is shut down to ignition off, but Zombie is kept powered on:

https://www.youtube.com/watch?v=l10xrlE ... Ax&index=1


In this test, ignition on is reapplied before the HV decays below Udcsw (set at 35V), and all contactors close and system powers up as expected:

https://www.youtube.com/watch?v=UJVqJoA ... Ax&index=2


This is the key video! In this next test, ignition on is reapplied after the HV decays below Udcsw. Note the pre-charge and negative contactors close, you can see the voltage momentarily jump up (24V) on the meter, but then drop to a few volts and the positive contactor never closes. Meter is measuring HV after the shunt and the HV+ fuse, so inverter HV input. I try ignition on a second time and same result. Then I power Zombie off and on again and retry and system powers up ok:

https://www.youtube.com/watch?v=2n4EZyo ... Ax&index=3


Here I repeated the same tests as above but using the HV Request input pin rather than ignition on. This video shows the system starting up from scratch. At the end, the HV Request is removed and the contactors open but Zombie remains powered:

https://www.youtube.com/watch?v=xIrZz0b ... Ax&index=4


With the system switched off (Zombie still powered) and HV decaying, HV Request is reapplied before voltage drops below Udcsw. Contactor sequence works ok and system powers up:

https://www.youtube.com/watch?v=CaDYfdU ... Ax&index=5


As above, HV Request is reapplied but after HV decays below the Udcsw value (35V), and unlike with the ignition on test above, the system now powers up as expected here:

https://www.youtube.com/watch?v=s6Kkkna ... Ax&index=6


Would appreciate any thoughts on what I'm seeing?

So precharge relay is dropping out then? If so it could be a bug in the timeout code

Edit: sorry, no you have leds indicating state
Can you disconnect the inverter HV?
Something is shorting out your precharge voltage. It must get quite hot

johu wrote: ↑Wed Dec 28, 2022 6:29 am So precharge relay is dropping out then? If so it could be a bug in the timeout code

Edit: sorry, no you have leds indicating state
Can you disconnect the inverter HV?
Something is shorting out your precharge voltage. It must get quite hot

Thank you for the reply Johu.
I have some videos of some more tests. The first three are repeats of earlier tests but with the meter leads moved to a different point in the HVJB setup (lead clamps can be seen in the videos). These three are attempted restarts after the system was turned on and running ok, then ignition switched off allowing HV to decay below Udcsw value, then attempts to restart the system. The meter negative lead is after the shunt on the connection to the inverter negative terminal.

In this video, the positive meter lead is after the fuse on the output of the positive contactor which is the connection to the inverter positive connection:

https://www.youtube.com/watch?v=m0kVkxY ... Ax&index=7

Here the meter positive lead is moved to after the pre-charge resistor and before the positive line fuse:

https://www.youtube.com/watch?v=htS6u9r ... Ax&index=8

Here the meter positive lead is moved to before the pre-charge resistor after the output of the pre-charge contactor. Notice that the full HV (49V) is seen here. So in all these tests, the full test HV is available to all contactors, and is available through the negative and pre-charge contactors, but only reads a few volts after the pre-charge resistor and the positive HV fuse.

https://www.youtube.com/watch?v=FuY_wtf ... Ax&index=9


For this last test, I disconnected the inverter HV positive lead from the output of the HV positive fuse so inverter was out of the system.

https://www.youtube.com/watch?v=L37KgYa ... x&index=10


I'm not sure this makes sense, the 49V available before the pre-charge resistor but only a few volts after the resistor and in the HV+ line? If there is shorting, it would seem to relate to the inverter only? But then, the HV Request input works as expected in all these same tests with the inverter also in the setup, and by cycling power to the Zombie VCU and retrying the tests, everything will work then.

Does that suggest that the Zombie and the power cycle fix the problem and so could relate to resetting some of the VCU inputs/outputs? Or simply just an artifact of the test HV batteries I'm using. Not just sure what to think on this one or what to check!

Maybe when started from scratch the inverter is not enabled and takes no current, but when restarted the current is higher and therefore drops too much voltage across the precharge resistor. If this is the case a lower value precharge resistor might help. From the video it looks like it's dropping 47-48V across the resistor so taking about 0.5A.

royhen99 wrote: ↑Fri Dec 30, 2022 9:27 pm Maybe when started from scratch the inverter is not enabled and takes no current, but when restarted the current is higher and therefore drops too much voltage across the precharge resistor. If this is the case a lower value precharge resistor might help. From the video it looks like it's dropping 47-48V across the resistor so taking about 0.5A.

Thank you for the reply. I can try some different resistor values. Wondering what would change then by turning off and on the VCU power to restart the VCU. Everything works as normal again after a power cycle

A note to add on the tests mentioned earlier.

After some more tests, I've noticed that when the system is powered up the first time (after zombieverter powered on, or power cycled), and ignition and start signals, the pre-charge works and HV is applied to the inverter and system can run ok. While doing this, there is no movement at all from the output of the gearbox or no clunk suggesting motors are trying to turn. The same is true when restarting the system before HV decays to below the Udcsw value.

However, when trying to restart when HV has decayed to below the Udcsw value, and ignition is turned on and start signal applied, just when the meter in the videos above shows the voltage suddenly drop to a few volts, the output of the gearbox jolts slightly. sometimes you can just hear the clunk of the motors starting to turn slightly over the noise of the contactors. It's like the pre-charge contactor closes, voltage starts to come up, motors for some reason just go to turn slightly, and then the HV after the pre-charge resistor drops so Udcsw is not hit and positive contactor won't close.

As mentioned above, simply cycling power to the VCU and trying again let the system power up and run as it should. Also, the HV Request method of bringing on HV works in all cases.


So what would make the motors want to turn in that use case when the HV has dropped below Udcsw and a restart is requested? Would that have to be the VCU requesting the inverter to try run the motors? And if so, could that be a slight glitch in the firmware (such as something not resetting)?

Or can that be explained electrically (inverter cap vs battery for testing, or wiring)?

You’ve probably thought of this but when the motor jolts are you seeing any torque request?

AdrianB wrote: ↑Sun Jan 01, 2023 9:42 am You’ve probably thought of this but when the motor jolts are you seeing any torque request?

No, not showing any torque request when plotting

Got back to a few tests I wanted to run on this issue. Plan was to repeat while connecting/reconnecting different combinations of MG1 and MG2 cables to the inverter to isolate the cause. Also wanted to test the effect of Park/HSDN signal as this is intended to shut off inverter drive when signal is high.

Test 1: Baseline. Create the HV restart issue

• Still using 4 x 12V batteries in series for HV supply (49V), started system up from complete shut off and contactor control works and motor spins

• Ignition off and contactors open as normal. Before HV at inverter input drops below UDCsw (set at 35V), reapplied ignition and start signals and contactors work and motor spins again

• Ignition off and contactors open as normal. Wait until HV at inverter input drops below UDCsw, reapplied ignition and start signals and contactor previous issue reappears. Negative and pre-charge contactors close but HV suddenly drops to a few volts (something shorts?) and HV positive contactor doesn't close as UDCsw value never reached, start times out

Test 2: Park/HSDN signal

• Start system up again and get motor spinning

• Ignition off and contactors open as normal. This time put transmission into park so HSDN signal to inverter goes high

• Wait for HV to drop below UDCsw and restart. This time system starts up as expected, unlike baseline, inverter whines and motors spin

Test 3: MG1 disconnected from inverter, MG2 connected

• Start system up again and get motor spinning

• Ignition off and contactors open as normal. Park/HSDN not connected

• Wait for HV to drop below UDCsw and restart. This time system starts up as expected, unlike baseline, inverter whines and motors spin

Test 4: MG1 and MG2 disconnected from inverter

• Start system up again

• Ignition off and contactors open as normal. Park/HSDN not connected

• Wait for HV to drop below UDCsw and restart. This time system starts up as expected, unlike baseline, no motors connected to spin

Test 5: MG2 disconnected from inverter, MG1 connected

• Start system up again and get motor spinning

• Ignition off and contactors open as normal. Park/HSDN not connected

• Wait until HV at inverter input drops below UDCsw, reapplied ignition and start signals and contactor previous issue reappears. Negative and pre-charge contactors close but HV suddenly drops to a few volts (something shorts?) and HV positive contactor doesn't close as UDCsw value never reached, start times out

• As with baseline, restarting before HV drops below UDCsw works as expected, but restarting after HV drops below UDCsw causes the issue

Test 6: Swap to a second inverter and repeat tests

• Same results

Next Steps:

• The Park/HSDN signal at start or restart solves the issue, but I don't believe HSDN should be required in a typical conversion. Others are operating without it from what I see. So still a route cause to be found

• The issue is MG1 specific, so I need to remove and inspect the MG1 transmission to inverter cables. Could be a cable issue, or transmission MG1 issue, or maybe still a code issue trying to drive MG1 at the wrong time? Will do some checks

• I probable need to try some measurements/tests on MG1 motor windings or isolation tests, but need to figure out what to check and how