# Nissan Leaf electric motor position sensor (resolver)



## dadazan (Apr 21, 2018)

Hi, I'm new in the forum. I'm converting an old Westfalia into 100% electric using Nissan Leaf components. My question is about the resolver (position sensor) of the electric motor:

Basically, I swapped 2 (of 3) phases of the Nissan Leaf AC motor to change the driving direction (Because installed the other side). *When I try to spine the wheel, nothing happen and I suspect the resolver.*

The Nissan Leaf electric motor position sensor: p/n: 34VRX-1004-C01S

Here's my questions:
1) What are the 6 wires going out from the resolver?
2) Is it a 10 poles/ 3 phases / 4 magnets resolver? Where can I find a wiring diagram and/or a schematic view for me to understand?
3) Do I need a new custom resolver for my use or I can just retrofit the existing one my swapping wires? If yes, which wires? 

Thank you very much! Help will be very appreciated since I'm stock.


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## Hollie Maea (Dec 9, 2009)

dadazan said:


> Hi, I'm new in the forum. I'm converting an old Westfalia into 100% electric using Nissan Leaf components. My question is about the resolver (position sensor) of the electric motor:
> 
> Basically, I swapped 2 (of 3) phases of the Nissan Leaf AC motor to change the driving direction (Because installed the other side). *When I try to spine the wheel, nothing happen and I suspect the resolver.*
> 
> ...


Why not just command an opposite direction, and keep the phases and the resolver set up normally?


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## brian_ (Feb 7, 2017)

dadazan said:


> 1) What are the 6 wires going out from the resolver?


I know almost nothing about resolvers, but it seems likely that the 6 wires are three pairs: one for excitation, and two for outputs (sine and cosine). But perhaps you know that and are asking which wire has which function in this specific resolver - sorry, no idea.


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## brian_ (Feb 7, 2017)

Hollie Maea said:


> Why not just command an opposite direction, and keep the phases and the resolver set up normally?


I agree, that makes more sense... but if the vehicle uses the complete Leaf control system, will it happily drive in reverse at full speed? Electrically this is fine, and mechanically it's fine because the Leaf gearbox is not being used, but the control logic is designed with some assumptions about how a car is driven.


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## dadazan (Apr 21, 2018)

Hollie Maea said:


> Why not just command an opposite direction, and keep the phases and the resolver set up normally?


It was a decision I made earlier in the process. Unfortunately, everything is well installed in place and it's difficult to go back. Probably it will be my plan B. As a plan A, I now have access to the connector of the resolver so I can swap wires


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## brian_ (Feb 7, 2017)

It appears that the Leaf resolver was developed and is produced by MinebeaMitsumi, which has a web page dedicated to it:
Rotation angle sensor (resolver) for EV/HEV drive motor
Although a traditional resolver uses external excitation on one of the wire pairs (as I mentioned above), this statement


> The angle is detected by means of an electric signal generated due to the change in reactance of the rotating rotor and fixed stator.


and the appearance of the physical configuration suggest that this "VR" (variable reluctance) design produces three separate sinusoidal outputs; the excitation method isn't clear, but it seems to me that there must be one or there would be no position information at zero speed.

While that page doesn't specifically answer your questions, there may be useful information in the MinebeaMitsumi site.


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## brian_ (Feb 7, 2017)

dadazan said:


> 2) Is it a 10 poles/ 3 phases / 4 magnets resolver? Where can I find a wiring diagram and/or a schematic view for me to understand?


From the MinebeaMitsumi product page, this appears to be a "4X" rotor variant of the VRX (variable reluctance) series, and you can determine whether it is in the 15 or 21 frame size from the dimensions (I'm guessing the 21VRX). That gives you a specific model - if the Leaf is using a standard model design - and perhaps that site or another one offers more detail for that specific model.

The product page does list specs, including a 7VRMS input (excitation) voltage, and 10 kHz frequency (presumably of excitation), but I haven't seen wiring details.


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## brian_ (Feb 7, 2017)

You might want to check with Paul (_MPaulHolmes_)... he posted an earlier thread here with similar questions:
_*Nissan Leaf motor resolver datasheet*_
and in another forum with more technical detail:
_*nissan leaf resolver specs*_
... and although there are no answers in those threads he reported in the other forum that he was able to build a resolver-to-encoder converter, so he must have figured out the wiring:
_*Nissan Leaf Motor Test with my homemade controller*_

In the "specs" post, Paul lists the terminations:

R1-R2 - excitation input
S1-S3, S2-S4 - outputs
I don't know if the terminals have these markings, or if swapping S1-S3 with S2-S4 would provide the desired reversal.


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## jhuebner (Apr 30, 2010)

Here is the info I used for designing my resolver interface:
http://productions.8dromeda.net/c55-leaf-inverter-protocol.html

Interface wise it's a completely standard resolver with a sine and cosine output and an excitation input. It has 4 pole pairs matching the motor, so gives you 4 electrical rotation per mechanical rotation.

Unlike encoders, resolvers output absolute angle info. Heres what you can try (including permutations)


Swap sin/cos (pins 17/18 to 20/21)
Swap sin polarity (17/18 to 18/17)
Swap cos polarity (20/21 to 21/20)
No sure of any of this will help, good luck.


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## Kevin Sharpe (Jul 4, 2011)

dadazan said:


> Basically, I swapped 2 (of 3) phases of the Nissan Leaf AC motor to change the driving direction (Because installed the other side).


It's a long time since I worked with the Leaf drivetrain but iirc the motor uses splash lubrication and won't run reliably in permanent reverse 

Probably worth asking Mike Schooling (here) at Indra before you go to far down this path


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## dadazan (Apr 21, 2018)

brian_ said:


> From the MinebeaMitsumi product page, this appears to be a "4X" rotor variant of the VRX (variable reluctance) series, and you can determine whether it is in the 15 or 21 frame size from the dimensions (I'm guessing the 21VRX). That gives you a specific model - if the Leaf is using a standard model design - and perhaps that site or another one offers more detail for that specific model.
> 
> The product page does list specs, including a 7VRMS input (excitation) voltage, and 10 kHz frequency (presumably of excitation), but I haven't seen wiring details.


I have communicate with Minebea with my questions but no response yet (This forum is way faster for information!). As mention above, the part number is 34VRX-1004-C01S on the 2016 Leaf. so it mean the frame size mounting is 34, the speed is 4X


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## dadazan (Apr 21, 2018)

jhuebner said:


> Here is the info I used for designing my resolver interface:
> http://productions.8dromeda.net/c55-leaf-inverter-protocol.html
> 
> Interface wise it's a completely standard resolver with a sine and cosine output and an excitation input. It has 4 pole pairs matching the motor, so gives you 4 electrical rotation per mechanical rotation.
> ...


Wow thanks, it'll sure be a first test. Question: Why not make a permutation of R1 (pin19) and R2 (pin27) ? Maybe I need to create/find a graph for a visual understanding..


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## dadazan (Apr 21, 2018)

Kevin Sharpe said:


> It's a long time since I worked with the Leaf drivetrain but iirc the motor uses splash lubrication and won't run reliably in permanent reverse
> 
> Probably worth asking Mike Schooling (here) at Indra before you go to far down this path


I think it's only the reduction gear with oil. Usually, it's pretty simple and oil is at the bottom of the pan and the gears are soak at the bottom... but it's what I think and I have no data on it, so yes, I will check it for sure! Thanks for the input


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## brian_ (Feb 7, 2017)

Kevin Sharpe said:


> It's a long time since I worked with the Leaf drivetrain but iirc the motor uses splash lubrication and won't run reliably in permanent reverse





dadazan said:


> I think it's only the reduction gear with oil. Usually, it's pretty simple and oil is at the bottom of the pan and the gears are soak at the bottom...


I agree - this is far more likely to be an issue with the gearbox than with the motor. This sort of lubrication is normal for a transmission with gears on parallel shafts and without hydraulic controls (e.g. a traditional "manual", not an "automatic"), and that's what's in a Leaf (and Tesla, and almost everything else).

I have no idea how the motor bearings are lubricated. Is the motor cooling oil (which is presumably ATF - automatic transmission fluid) circulated through the motor's bearings?


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## dadazan (Apr 21, 2018)

jhuebner said:


> Here is the info I used for designing my resolver interface:
> http://productions.8dromeda.net/c55-leaf-inverter-protocol.html
> 
> Interface wise it's a completely standard resolver with a sine and cosine output and an excitation input. It has 4 pole pairs matching the motor, so gives you 4 electrical rotation per mechanical rotation.
> ...


I've done the modification on the wires. The wheels are moving (i'm happy) but....:
D: going in the right direction (reverse way)
R: going in the same direction of D ?????? but less power

I honestly don't understand this behavior...


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## dadazan (Apr 21, 2018)

I've tested almost every combination of the resolver wires but still doesn't work.

I suspect the traction motor offset. Every electric motor is unique (You cannot swap two Leaf electric motor unless you register the new offset in the system).

In my case, as an example, IF my traction motor is 5deg offset, I need to register -5deg (and swapping the right wires of the resolver ---s1 to s4 and s2 with s3).

Every offset in stamp under the traction motor. But now.... What does the stamp code mean? degree? rad? minutes? (see picture)


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## kennybobby (Aug 10, 2012)

Looks like a hexadecimal number scheme. Can you read a couple of real codes off of some cars and post them up here--may be able to cipher the offset meaning after looking at the hex codes.


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## arber333 (Dec 13, 2010)

dadazan said:


> I've tested almost every combination of the resolver wires but still doesn't work.
> 
> I suspect the traction motor offset. Every electric motor is unique (You cannot swap two Leaf electric motor unless you register the new offset in the system).
> 
> ...


Yes i had the same problem you have. I have older version of motor and resolver. You could be 180deg off in your offset. I will try to look up what hex digit i have on my motor. I think i had 21pt offset. And when i used 180deg version i got spinning without effective regen. You could use same setting and just change phase cables...

I will be doing more with my Leaf motor and i will write about it here:
https://leafdriveblog.wordpress.com/

There is also old motor resolver connector wiring detailed. I am not sure it is the same though:
https://leafdriveblog.wordpress.com/2016/11/16/resolver/

A


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## Drum (May 26, 2017)

Hi, I have seen a video (sorry, can't find it again) where some testers in America got Nissan technicians to "unlock" the Nissan Leaf speed restriction in reverse, and set what they claimed was a world record speed in reverse, smashing the old record by a huge margin. They said something like "It will go just as fast in reverse as in forward now, we just have to keep it on the road".
There is a current video of a stunt driver completing the Goodwood Festival of Speed hillclimb in reverse in a Leaf, averaging 88kph.
Therefore I believe that the Leaf motor in standard wiring configuration is capable of running full speed in "reverse", and that the 50kph limit is a setting in the vehicle management system that can be bypassed if you know how.
I have no personal experience, this is just from seeing the videos, but I would be researching that possibility before tackling the reversal of wiring etc.
Good luck!
Dave


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## Kevin Sharpe (Jul 4, 2011)

Drum said:


> Therefore I believe that the Leaf motor in standard wiring configuration is capable of running full speed in "reverse"


If you swap two of the phase cables the motor will run at full speed in 'reverse'. However, the issue is the splash lubrication which only works in one direction, 'forward'.


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## brian_ (Feb 7, 2017)

Kevin Sharpe said:


> If you swap two of the phase cables the motor will run at full speed in 'reverse'. However, the issue is the splash lubrication which only works in one direction, 'forward'.


... in the transaxle, not the motor, right?


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## brian_ (Feb 7, 2017)

Drum said:


> Therefore I believe that the Leaf motor in standard wiring configuration is capable of running full speed in "reverse", and that the 50kph limit is a setting in the vehicle management system that can be bypassed if you know how.


Since the direction of rotation doesn't matter to the motor electrically, magnetically, or mechanically, and doesn't matter to the inverter's power stage (just to the controller and drivers) this isn't a surprise.

The speed in reverse is limited to prevent the car from being driven in reverse at excessive speed, and probably to keep the rest of the drive unit (transaxle and cooling system) from being rotated in reverse for too long. My understanding is that dadazan isn't using any of those other components - just the motor. I don't know how the motor is lubricated.



Drum said:


> I have no personal experience, this is just from seeing the videos, but I would be researching that possibility before tackling the reversal of wiring etc.


See post #5.


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## rowen01960 (Jun 17, 2018)

So .... to reverse the typical Leaf Motor/Reducer installation, ie Motor is now AFT of the Drive Shafts, one needs only to resolve the Reducer gear lubrication splash? ... perhaps a custom Reducer Housing with appropriate galleys? All else is doable?


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## drother (Sep 11, 2014)

brian_ said:


> I don't know how the motor is lubricated.


The motor uses sealed bearings. Grease only. They won’t care about direction.


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## rowen01960 (Jun 17, 2018)

Ahh ... so an “equivalent” Gear Reduction Housing with rearranged Oil Galley(s) should allow the motor (after electrical mods) to run full time in reverse?


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## brian_ (Feb 7, 2017)

drother said:


> The motor uses sealed bearings. Grease only. They won’t care about direction.


Good to know 

So motor bearings are not lubricated by oil which is also circulated for cooling, or oil which is also used for the reduction gears (both of which are common practices).


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## drother (Sep 11, 2014)

brian_ said:


> Good to know
> 
> So motor bearings are not lubricated by oil which is also circulated for cooling, or oil which is also used for the reduction gears (both of which are common practices).


Motor is dry, only the reduction box has oil (ATF) lubrication


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