How to freewheel a Leaf motor with a Zombieverter

Nissan Leaf/e-NV200 drive stack topics
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m.art.y
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How to freewheel a Leaf motor with a Zombieverter

Post by m.art.y »

Hi, so there is a plan to construct a hybrid van, where diesel engine would remain at the front and Nissan motor at the back. Idea is to only run electric around town and diesel on longer trips. Would there be a problem freewheeling a permanent magnet motor like Leaf for long distances and how could that be achieved with a ZombieVCU? Any insight/advice appreciated 😊
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by Pete9008 »

You would have to be careful not to go much above base speed. If you did, without the inverter being active to control the motor back EMF, it could overvolt the inverter!

Edit - not sure what would happen if you powered the inverter but requested zero torque? It might be perfectly happy, and even allow regen braking, but then again it might not.
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by bexander »

My best guess is to request 0 torque from the inverter by sending 0 torque command from the ZombiVCU.
Any permanent motor will act as a generator if the inverter for it is not powered. Feeding current back to the battery through the body diodes on the IGBT:s. Above base speed you will likely create overvoltage and brake something if inverter is not powered and commanded to 0 torque.

This is a drawback with PM motors and for this case it is actually better with a induction motor. An IM will not act as a generator in the same maner with an unpowered inverter.
The tesla model 3 uses PM motor at rear axel and IM at front axle and I belive this is to have the best efficiency at low power levels where only the rear motor is powering the car and the front motor is just coasting along.
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by Pete9008 »

Agree, thinking about it you would have to power the inverter up. Does add some interesting possibilities too, regen braking, extra power boost if needed even recharging the battery while driving on the ICE, a proper hybrid!
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by m.art.y »

bexander wrote: Sat Jan 07, 2023 11:27 am Any permanent motor will act as a generator if the inverter for it is not powered. Feeding current back to the battery through the body diodes on the IGBT:s. Above base speed you will likely create overvoltage and brake something if inverter is not powered and commanded to 0 torque.
And if inverter is powered, battery connected and 0 torque is requested could it freewheel then? What would that base speed be? Obviously diesel engine would spin it up on a highway.
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by m.art.y »

Pete9008 wrote: Sat Jan 07, 2023 11:33 am Agree, thinking about it you would have to power the inverter up. Does add some interesting possibilities too, regen braking, extra power boost if needed even recharging the battery while driving on the ICE, a proper hybrid!
Yes, this is the idea if it would work? 😊 Wouldn't need extra power boost as the diesel is very powerful, but regen would be good. The question is if this can be done and would this cause issues when diesel will be spinning it up on a highway? What would that base speed be?
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by Pete9008 »

Depends on your battery voltage but probably 4-5krpm motor speed?

No idea whether anything in the Leaf inverter would object, shouldn't do as it is just like coasting. Might be worth checking what the Leaf towing recommendations are?

Edit - just remembered this https://www.locostbuilders.co.uk/v ... 5&page=1 , might be worth a look?
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by bexander »

m.art.y wrote: Sat Jan 07, 2023 12:02 pm And if inverter is powered, battery connected and 0 torque is requested could it freewheel then? What would that base speed be? Obviously diesel engine would spin it up on a highway.
Yes, I think it will and you would not need to care about base speed or not, as long as you don't force the leaf motor above maximum rated speed, 10400rpm or something like it, with no torque requested the inverter will frewheel the motor. Note that the inverter in this state will draw a current from the battery as it needs to spin the motor electrically to keep the torque at zero. The current drawn will depend on the motor speed. I saw approx 3A at 370V when freewheeling my Clio at 70km/h (5400rpm on the motor).
When you want regen send a negative torque request to the inverter.
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Re: How to freewheel a Leaf motor with a Zombieverter

Post by arber333 »

I can provide some insight about that. Although for lebowski not OI.
When i run the car downhill and speed is below the knee i can close the brake pot and release the throttle and the car just rolls down the hill. Consumption is about 3A which ammounts to dcdc draw.
If i would then reach the knee (fw speed) i would see the amps slowly going to 0A and then cross into +. With throttle released and motor running at 9000rpm i see some 5A going back at 380Vdc. Not shabby but definitely too much for DC link cap to absorb.
I have run Leaf motor at speed 12000rpm and it seemed fine there. But sanity prevailed and i reduced logic back to 10000rpm.

DC contactor needs to be on the whole time car is driven.
But you can use the diesel to charge your batteries while on the road. Road will provide linkage...

A question feels appropriate now. Would disconnecting both REV/FWD pins cause inverter to freewheel? Then your problem is solved.
Edit: sorry that was meant for use of OI board not OEM inverter via torque commands.
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