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JeremyW
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Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

MiM: Tricking the inverter for better performance

Tue Sep 30, 2014 10:02 am

As a few of you know I've been bugging everyone I've met at Nissan for the coveted "Nismo VCM" upgrade that is ONLY available in Japan. Since it's very very very restricted (it must be done in Japan on a '13+ leaf, etc etc) by Nissan I've begun to explore different avenues on how to get the equivalent performance. What follows is what I would call "Stage 1" which would be a Man-in-the-Middle technique of putting a box in between the CAN lines of the inverter and the rest of the bus. The box would consist of two AVR-CAN devices running a 1mb/s serial link between them. One side interprates the 1DC requested torque messages, adjusts it as needed, corrects the CRC byte(s) to make it a valid message, and finally sends it to the other side which turns it back into a CAN message for the inverter to see.

That's the theory anyway. Over the next few months I will try to see if it works. From what I've read in the service manual, the inverter will dial itself back if it or the motor gets too hot (there's 5 temperature sensors within the inverter on the 2011-2012 models).


Warning: this may be an easy way to break things like half shafts, gears, the motor, other cars or property, my own car or property, or worse. This is *highly* experimental.
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

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GeekEV
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Location: NorCal, USA

Re: MiM: Tricking the inverter for better performance

Tue Sep 30, 2014 12:43 pm

Planning on running the modified class at REFUEL 2015 are we? :D

2014 Chevy Spark EV 2LT
2013 Tesla Model S 60kWh[/url]
AV L2 EVSE + kWh meter
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JeremyW
Posts: 1518
Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

Re: MiM: Tricking the inverter for better performance

Tue Sep 30, 2014 12:50 pm

GeekEV wrote:Planning on running the modified class at REFUEL 2015 are we? :D

The goal is to get it done in time for that, yes. :)
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

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GeekEV
Posts: 1825
Joined: Tue Jan 18, 2011 4:11 pm
Delivery Date: 15 Feb 2011
Leaf Number: 0308
Location: NorCal, USA

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 1:01 pm

JeremyW wrote:
GeekEV wrote:Planning on running the modified class at REFUEL 2015 are we? :D

The goal is to get it done in time for that, yes. :)

Oh yeah? I have this harebrained idea to mist liquid nitrogen into the radiator intake of my Tesla to improve cooling and try to prevent power limiting. Whatcha think about that? ;)

2014 Chevy Spark EV 2LT
2013 Tesla Model S 60kWh[/url]
AV L2 EVSE + kWh meter
9.4kW Solar Array + enphase energy

LeftieBiker
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Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 1:31 pm

Why would throttling back the inverter increase power from the motor? Especially if the motor power commands include those that limit output from a dead stop?
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

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JeremyW
Posts: 1518
Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 2:31 pm

The inverter only throttles back if things get too hot to protect itself and/or the motor stator. Under normal conditions it should accept the torque values and implement them. I've got a few graphs at home showing the torque message from the VCM during a full throttle acceleration from stop. There is a significant amount of de-rating for the first second or two. We also do not know if the inverter will accept torque values higher than what the VCM currently maxes out at.

Another consideration is how much extra power/torque did Nissan leave on the table? What is the weak link in the drive train? Will I hit it early and break something expensive? :|
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

User avatar
JeremyW
Posts: 1518
Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 2:54 pm

GeekEV wrote:I have this harebrained idea to mist liquid nitrogen into the radiator intake of my Tesla to improve cooling and try to prevent power limiting. Whatcha think about that? ;)

I think Tesla should offer a "Track" option which you enable a few hours before a track day on shore power which runs the AC to bring the pack down to like 15 C. That way you could do a few more runs before hitting any thermal limit. If you suggest it to them, can I get a bit of credit? ;)

I want this thread to stay as close to the topic at hand so please no extra discussion on this! :)
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

User avatar
GeekEV
Posts: 1825
Joined: Tue Jan 18, 2011 4:11 pm
Delivery Date: 15 Feb 2011
Leaf Number: 0308
Location: NorCal, USA

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 4:13 pm

JeremyW wrote:
GeekEV wrote:I have this harebrained idea to mist liquid nitrogen into the radiator intake of my Tesla to improve cooling and try to prevent power limiting. Whatcha think about that? ;)

I think Tesla should offer a "Track" option which you enable a few hours before a track day on shore power which runs the AC to bring the pack down to like 15 C. That way you could do a few more runs before hitting any thermal limit. If you suggest it to them, can I get a bit of credit? ;)

I want this thread to stay as close to the topic at hand so please no extra discussion on this! :)

Bah. :cry:

2014 Chevy Spark EV 2LT
2013 Tesla Model S 60kWh[/url]
AV L2 EVSE + kWh meter
9.4kW Solar Array + enphase energy

LeftieBiker
Posts: 7205
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 5:26 pm

I asked an on-topic question and was ignored. I'm going to assume the inverter is inline between the controller and motor, and leave it at that.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

User avatar
JeremyW
Posts: 1518
Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

Re: MiM: Tricking the inverter for better performance

Wed Oct 01, 2014 6:10 pm

Ok leftie let me be more clear:

LeftieBiker wrote:Why would throttling back the inverter increase power from the motor? Especially if the motor power commands include those that limit output from a dead stop?
It doesn't. The throttling back only happens if things overheat. I'm not throttling back the inverter. The inverter itself would throttle back power, ignoring higher torque commands if the motor or the inverter gets too hot.

The VCM, vehicle controller, is the one taking in the throttle position and speed and sending out a torque command to the inverter. The idea is to intercept the torque command message from the VCM, change it to a higher value, then send it on to the inverter.
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

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