Surron Motor tuning with datalogs! FOC experts needed

[Ohbse]

My favorite controller by a mile, the Nucular 24f has recently added the ability to datalog to the onboard microSD card. This allows for some awesome analysis that previously would only be possible with a handful of high end controllers and custom logging solutions or with a lot of external, expensive sensors on a Dyno.

As an example, here's an acceleration run up the moderate hill next to my house. Peak power of 13.4kw, 500a phase, peak of 235a battery on my 16s pack. Battery amps limit was set to 300a here and the pack can support that in a burst.




While the bike isn't slow (remembering this is up a big hill to deliberately load it up more than normal) I am wishing for more area under the curve. Power peaks very sharply and then falls off rapidly. The area that I was immediately drawn to is Motor voltage - beyond a specific RPM this increases very non-linearly. Is this expected behaviour? I've heard the Surron motor is a weird one. This is the limiting factor here in power output - the controller limits motor V to the silicon voltage limit. The no load speed with the same settings here is >130km/h with motor voltage of only 65v

For that same run, here's the graph of some of the FoC parameters over same time period


These logs were taken with 100ms polling intervals, this can be altered to 1ms or even finer, but I haven't done enough tests with this yet. This is a Beta feature and I've already identified one issue with attempting to log at 10ms interval - under acceleration from 0-64km/h with high throttle the log cuts out with 5.9s of skipped data. This happens on the street or on the stand with no load.

Has anybody got any explanation for the behaviour I'm seeing? Is there any specific tests that would be of benefit to run? From 30km/h to 60km/h torque has halved and this is very obvious while riding. If I could extend the usable RPM range of peak torque this bike would be amazing.

 

[flat tire]

Looks normal. Is the motor supposed to do more at your voltage?

 

[peters]

I see what you mean but can't explain.
You'd expect a flat horizontal section on the battery current (and power) curve after the peak, that would be a range where the peak batt current setting limits the acceleration, and the fall off would be only at higher RPM.
The positive bump on the FOC Id graph seems to be in conjunction with the battery current falling off, and after that the negative Id shows the field weakening is in operation. Maybe try to turn the FW completely off and check the difference.
Or for a test lower the battery current limit (100..150A), because then the expected flat part of the curve would be longer.
(note it's just theoretical, I don't have a Nucular controller or Surron motor)

 

[Tolkano]

Any updates on this? I understand the motor current dropping off as you run out of phase amps but why does the battery current also drop off in the mid/high end?

 

[st35326]

I believe the drop off is from back EMF countering pack voltage. I've found the easiest way to tune, if your interested in performance, is to run from a stop to full throttle 0-30mph, 0-40mph and 100 meter elapsed time via the Dragy. What I do is make a change, then go out and log all three in one WOT blast, on the Dragy.

Then I can see what changes effect acceleration and how. Generally more phase amps = faster times, for me up to saturation point. Stator heat and battery sag (lowest voltage) are logged and noted via the Cycle Analyst as well as max DC amps through the shunt.

 

[Ohbse]

Any updates on this? I understand the motor current dropping off as you run out of phase amps but why does the battery current also drop off in the mid/high end?

That is the million dollar question! This is doubtless due to BEMF, however the fact that it increases so non-linearly with motor RPM is unusual to me.

I have done a bunch of iterative testing with various settings. The best performance was with my original settings, with everything essentially maxed out. Unfortunately I haven't found a combination of settings that will result in a longer constant power section as I would expect and have observed on other controllers running this motor.

I haven't been riding much given NZ has been under full lockdown which we are exiting tomorrow.

If anybody has some ideas for FOC changes that could extend the useful power range of this motor, please let speak up!

 

[thoroughbred]

What kind of parameters have you been adjusting? I'm trying to learn what to tweak to get a mobipus 200 working on the surron

 

[John in CR]

It looks like that knee in the battery current occurs as the field weakening kicks in, so I'd definitely start with the FW turned off. That will give you a more gradual tapering of battery current with rpm due to BEMF. FW is for extending top speed, and your graph seems to confirm what I've suspected for a while...that FW can negatively impact lower rpm.

Also, motor temps will be a big factor running those kinds of currents, especially since that little motor can't handle what a 24F can deliver except in short bursts, so be careful not to compare results from a cold motor with a hot one.

 

[district9prawn]

The point in the curve where battery current suddenly drops off and motor voltage sharply increases, corresponds to a spike in Id. But it's POSITIVE! It looks like field weakening is going wrong.

 

[Ohbse]

I realised I never posted an update here - vasiliy released new firmware based on mine and others feedback which completely resolved the non linear behaviour and now this thing RIPS.

Still on 16s stock battery with a parallel booster pack from old 30qs, now hits 16.2kw on a daily basis. Power does not drop off hardly at all, dramatically increasing rates of acceleration above 50kmh. Removed plural seconds from my 0-80kmh time. Top speed now 110+, frankly I don't care to test beyond that - it's not what this bike is for.

16km journey with 10-15 full throttle 500a phase amp starts (depending how many red lights I get), cruising at 60km/h, peaks of 85kmh, power consumption averages 45-50wh/km. Motor Temperature on arrival is 55-65 degrees C depending on how hard I'm pushing.

Have done about 2500km with this setup - it works great.

Things I would change:

Gearing - I would hear this down further now that firmware has extended my effective speed range. That would give me that much more off the line - right now I'm still not able to power wheelie if I shift my weight forward so there's more acceleration to be had. Unfortunately the belt setup does not lend itself to this well. Allexs belt setup would be ideal and is superior to the Luna option, but I can't justify spending the money.

Voltage - a 20s pack with stiff cells capable of maintaining 250-300a combined with gearing change would be perfect imo for the motor and controller combo. Higher starting torque from the gearing plus extended range of peak torque, this would make 0-100kmh runs feasible and genuinely decent. 0-80kmh there wouldn't be much around that could complete with this combo. Going any further is exceeding motor capabilities and would become too inefficient.

Brakes - stock brakes aren't up to the task at this power level if you're pushing it. 95% of my braking is done with variable Regen on my left grip, but at higher speeds mechanical brakes are still required and the stock ones with upgraded pads struggle.

FW is for extending top speed, and your graph seems to confirm what I've suspected for a while...that FW can negatively impact lower rpm.

Also, motor temps will be a big factor running those kinds of currents, especially since that little motor can't handle what a 24F can deliver except in short bursts, so be careful not to compare results from a cold motor with a hot one.

New firmware fixed this issue. New graph just has MORE everywhere from 40kmh onwards. No downside at all!

I am running 100% maxed out controller settings on this little motor and as above, ride often and hard. Zero issues. Power is certainly reduced at 65c vs 20c, but not even close to reaching the exponentially inefficient range. All my testing I do from room temperature to normalise results. When it stops raining I will go get another log on the same course and publish the improvements

 

[sn0wchyld]

I realised I never posted an update here - vasiliy released new firmware based on mine and others feedback which completely resolved the non linear behaviour and now this thing RIPS.

Still on 16s stock battery with a parallel booster pack from old 30qs, now hits 16.2kw on a daily basis. Power does not drop off hardly at all, dramatically increasing rates of acceleration above 50kmh. Removed plural seconds from my 0-80kmh time. Top speed now 110+, frankly I don't care to test beyond that - it's not what this bike is for.

16km journey with 10-15 full throttle 500a phase amp starts (depending how many red lights I get), cruising at 60km/h, peaks of 85kmh, power consumption averages 45-50wh/km. Motor Temperature on arrival is 55-65 degrees C depending on how hard I'm pushing.

Have done about 2500km with this setup - it works great.

Things I would change:

Gearing - I would hear this down further now that firmware has extended my effective speed range. That would give me that much more off the line - right now I'm still not able to power wheelie if I shift my weight forward so there's more acceleration to be had. Unfortunately the belt setup does not lend itself to this well. Allexs belt setup would be ideal and is superior to the Luna option, but I can't justify spending the money.

Voltage - a 20s pack with stiff cells capable of maintaining 250-300a combined with gearing change would be perfect imo for the motor and controller combo. Higher starting torque from the gearing plus extended range of peak torque, this would make 0-100kmh runs feasible and genuinely decent. 0-80kmh there wouldn't be much around that could complete with this combo. Going any further is exceeding motor capabilities and would become too inefficient.

Brakes - stock brakes aren't up to the task at this power level if you're pushing it. 95% of my braking is done with variable Regen on my left grip, but at higher speeds mechanical brakes are still required and the stock ones with upgraded pads struggle.

FW is for extending top speed, and your graph seems to confirm what I've suspected for a while...that FW can negatively impact lower rpm.

Also, motor temps will be a big factor running those kinds of currents, especially since that little motor can't handle what a 24F can deliver except in short bursts, so be careful not to compare results from a cold motor with a hot one.

New firmware fixed this issue. New graph just has MORE everywhere from 40kmh onwards. No downside at all!

I am running 100% maxed out controller settings on this little motor and as above, ride often and hard. Zero issues. Power is certainly reduced at 65c vs 20c, but not even close to reaching the exponentially inefficient range. All my testing I do from room temperature to normalise results. When it stops raining I will go get another log on the same course and publish the improvements

Good stuff mate... guess i need to update my firmware too ha.

 

[sn0wchyld]

I realised I never posted an update here - vasiliy released new firmware based on mine and others feedback which completely resolved the non linear behaviour and now this thing RIPS.

Still on 16s stock battery with a parallel booster pack from old 30qs, now hits 16.2kw on a daily basis. Power does not drop off hardly at all, dramatically increasing rates of acceleration above 50kmh. Removed plural seconds from my 0-80kmh time. Top speed now 110+, frankly I don't care to test beyond that - it's not what this bike is for.

16km journey with 10-15 full throttle 500a phase amp starts (depending how many red lights I get), cruising at 60km/h, peaks of 85kmh, power consumption averages 45-50wh/km. Motor Temperature on arrival is 55-65 degrees C depending on how hard I'm pushing.

Have done about 2500km with this setup - it works great.

Things I would change:

Gearing - I would hear this down further now that firmware has extended my effective speed range. That would give me that much more off the line - right now I'm still not able to power wheelie if I shift my weight forward so there's more acceleration to be had. Unfortunately the belt setup does not lend itself to this well. Allexs belt setup would be ideal and is superior to the Luna option, but I can't justify spending the money.

Voltage - a 20s pack with stiff cells capable of maintaining 250-300a combined with gearing change would be perfect imo for the motor and controller combo. Higher starting torque from the gearing plus extended range of peak torque, this would make 0-100kmh runs feasible and genuinely decent. 0-80kmh there wouldn't be much around that could complete with this combo. Going any further is exceeding motor capabilities and would become too inefficient.

Brakes - stock brakes aren't up to the task at this power level if you're pushing it. 95% of my braking is done with variable Regen on my left grip, but at higher speeds mechanical brakes are still required and the stock ones with upgraded pads struggle.

FW is for extending top speed, and your graph seems to confirm what I've suspected for a while...that FW can negatively impact lower rpm.

Also, motor temps will be a big factor running those kinds of currents, especially since that little motor can't handle what a 24F can deliver except in short bursts, so be careful not to compare results from a cold motor with a hot one.

New firmware fixed this issue. New graph just has MORE everywhere from 40kmh onwards. No downside at all!

I am running 100% maxed out controller settings on this little motor and as above, ride often and hard. Zero issues. Power is certainly reduced at 65c vs 20c, but not even close to reaching the exponentially inefficient range. All my testing I do from room temperature to normalise results. When it stops raining I will go get another log on the same course and publish the improvements

Good stuff mate... guess i need to update my firmware too ha.