EM57 motor to run a fixed rpm

Nissan Leaf/e-NV200 drive stack topics
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PaulHeystee
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EM57 motor to run a fixed rpm

Post by PaulHeystee »

Hi,
Does anyone know if it is possible to have the Leaf motor turn at a specified rpm?
I assume it can be done by software, however, I wanted to first ask
Did anybody do this before?

I want to have the motor to match same speed as the gearbox (not Leaf) to make gear changes while driving easier.

thanks
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Re: EM57 motor to run a fixed rpm

Post by Bratitude »

Yes. Are you using oi or can control? ether way you give it it a throttle command of the rpm you desire.
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Re: EM57 motor to run a fixed rpm

Post by Tremelune »

Easiest solution is to get better at rev matching.
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Re: EM57 motor to run a fixed rpm

Post by Alibro »

PaulHeystee wrote: Tue Oct 05, 2021 11:20 am Hi,
Does anyone know if it is possible to have the Leaf motor turn at a specified rpm?
I assume it can be done by software, however, I wanted to first ask
Did anybody do this before?

I want to have the motor to match same speed as the gearbox (not Leaf) to make gear changes while driving easier.

thanks
I've been changing gear without the clutch for years due to a bad left knee. Some cars are easier than others but mostly get the revs slightly higher than required and put gentle pressure on the gear stick so when the revs drop it slips into gear.
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Re: EM57 motor to run a fixed rpm

Post by johu »

The software lets you map the value "cruisespeed" to be read from CAN. Then set cruisemode to "CAN" and you're off. Send "-1" there to disable the speed control loop or any other speed to make the controller run at that speed.

One quirk: the speed controller is set up for cruise control, not idle motor speed control. So the control loop is too slow by default and will oscillate. Setting the parameter "cruiseflt" to 0 will cure that.

I do second Alibro in that I always shift without the clutch. Automating it seems too much of a hassle as you also need to communicate the target gear to your VCU.
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Re: EM57 motor to run a fixed rpm

Post by PaulHeystee »

Thanks for the replies!
The problem is that other drivers will use the converted Daihastu Rocky/Fourtrack so it must be easy to shift. Mainly from 2nd to 3rd or even 4th.
I normally drive it in 3rd, it is fast enough for town traffic, the 4th would be better when already upto speed. hence the gear shift.

I use a EV-resolve controller, I am not sure if this cruisespeed command is an inverter controlled thing or done by the EV-resolve VCU.
I would switch controllers if this can solve this issue, would the ZombieVerter be able to do this?

mvg
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Re: EM57 motor to run a fixed rpm

Post by Bratitude »

Having a “ready to shift to N gear” indicator might be worth considering then.

this is a bit of a slippery sloop, as setting up automatic throttle commands for matching gear rpms for shifts leaves a large margin of error....undesired acceleration...
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Re: EM57 motor to run a fixed rpm

Post by PaulHeystee »

Good point Bratitude, I guess the safest way is to simply add a milled down flywheel and clutch, old school shifting :-)
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Re: EM57 motor to run a fixed rpm

Post by EV_Builder »

PaulHeystee wrote: Tue Oct 05, 2021 7:55 pm Good point Bratitude, I guess the safest way is to simply add a milled down flywheel and clutch, old school shifting :-)
How would you do it without that then?
Without a clutch there isn't much to match ..
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Re: EM57 motor to run a fixed rpm

Post by celeron55 »

If you want to go with your original idea, you basically need to have a VCU that is freely programmable, add the necessary inputs to it, and program it to do this.

Basically it needs to somehow know if you're wanting to go to neutral gear (so that it can kill throttle and regen), and also afterwards it needs to somehow know which gear you're trying to engage, so that it can match the rpm. Also obviously it needs to have speed input from the gearbox and speed input from the motor.

HOW can it know which gear you're trying to switch to? I guess maybe with some sort of pressure sensors in the shifter knob or linkages.

Of course you have to program a PID loop to control the rpm using rpm feedback and torque commands, and for safety you'll want to limit the torque to something that won't move the vehicle but will change the rpm quickly.

My personal opinion is, get a gearbox with non-destroyed synchros, minimize the extraneous spinning mass and add a button to the shifter to kill throttle and regen. It's not super easy or super fast, but it's a system even the average grandma can learn to use if needed.

Even more personally, I don't have any of this. I just press the throttle to the deadzone between throttle and regen, pop it out of gear, then rpm match and engage the desired gear. Sometimes it grinds if I don't do it slowly and precisely enough, but most of the time not. It has lasted 50 000 km so far, in addition to the original 300 000 km. If my mom had to drive the thing, I'd tell her to just put it in 3rd.
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Re: EM57 motor to run a fixed rpm

Post by PaulHeystee »

Good point, Once the motor / controller knows the driver wants to change gears it would be simple and safe.
I guess the old clutch pedal can be utilised with a spring and a switch to give the signal to the controller. Once released it will go back into drive.
Perhaps also some switches on the gear selector to know which gear is trying to engage. In practice we need only 3 -> 4 and back.
It will be possible to get the speed of the gearbox with a hall sensor.
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Re: EM57 motor to run a fixed rpm

Post by arber333 »

PaulHeystee wrote: Sun Oct 10, 2021 2:40 pm Good point, Once the motor / controller knows the driver wants to change gears it would be simple and safe.
I guess the old clutch pedal can be utilised with a spring and a switch to give the signal to the controller. Once released it will go back into drive.
Perhaps also some switches on the gear selector to know which gear is trying to engage. In practice we need only 3 -> 4 and back.
It will be possible to get the speed of the gearbox with a hall sensor.
I am using Mazda gearbox and ACIM motor without clutch for a long time now. I use simple Mil rated switch on the shifter and whenever i want to shift i push the button and move the shifter toward the next gear. Synchros are perfectly capable of capturing motor speed, but regen needs to be off at the time.
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