openinverter forum

Hi Everyone,
I'm reaching out to get some troubleshooting tips on getting my LDU too spin on low voltage. Here's where I've gotten to:
- Openinverter board connected to LDU powers up fine and I can get to the home page.
- Using a 30V 10A bench power supply for HV testing and a freshly charged car battery for 12V supply
- Set UCDNOM to 0 and UDCSW at 20
- Precharge and main contactors connected and working properly (turning on and off at the right times)
- After the precharge and momentarily connecting the start pin, I'm showing 30V at the HV motor leads so I know it's getting power.
- Calibrated the throttle pedal and can map/see the values responding properly when I plot and try to push the pedal
- Tried removing the encoder and starting in manual mode starting at 5 for "fslipspnt" and increasing in increments of 5 up to 100

Motor does not spin for any of this.

Are there values I should be specifically looking at in the parameters to see if everything has been done properly or if something's not working? Any other suggestions?

Make sure to watch this if you haven't, it could help avoid an expensive mistake.

spiff wrote: ↑Sat Jul 22, 2023 1:27 am Motor does not spin for any of this.

Is it drawing any current? It might simply be that it's not pulling enough power to get spinning.

Hi spiff. If all your connections etc are ok as per Damiens video then you could try increasing Boost. When I first started I could not get my motor to run with a low voltage source, increasing Boost solved that but its only a suggestion ok. I guess you have direction fwd or rev enabled ?

Thanks everyone for the responses. I did recheck/test everything as per the video. All initial meter readings on the inverter were fine.
The board is getting power and when I turn the axles manually and plot the speed it registers so I know the encoder wiring and connections are also good.
Again the contactor circuits (pre-charge and main) are working as I can hear them clicking on and off at the right times, and I do see 30V at the motor leads after "start" is pressed and the opmode is in "run". Direction is engaged (pin 7) showing forward.

Thank you for the tip on Boost. I will try that next. Hoping to update this thread with success!

SUCCESS!!!!
After months of waiting for parts, replacing bearings and seals and then wiring everything up, the used motor that I bought 5 months ago that I had no idea whether is functional, actually spins!

Two things I ended up doing:
1. Needed to increase the boost value from default is 1700 to 10,000.
2. When I did that the axles started moving but very slowly and in a stuttering way. Even though I was using a stock tesla wire harness connecting the 23-pin port to the 4-pin encoder port, it looks like pins 2 and 3 needed to be swapped. Once I did that the axles responded smoothly to pedal inputs!

Thank you all. I'd like to contribute my own thoughts to the FAQ as there's a few things that I struggled with that may help others. Do I need special access? Where is the best spot... On here or github?

Great to hear!

Maybe pinswapping of two PWM phases should be ported to async code, too. Should make encoder wire swapping redundant, right?

spiff wrote: ↑Sun Jul 23, 2023 11:30 pm I'd like to contribute my own thoughts to the FAQ as there's a few things that I struggled with that may help others. Do I need special access? Where is the best spot... On here or github?

Perhaps the Wiki?

https://openinverter.org/wiki/Tesla_Model_S/X_Large_Drive_Unit_(%22LDU%22)#Encoder_Issues

To edit the Wiki, all you need is to be logged in with your usual OI credentials; no special access needed.