ElectricMotorcycleForum.com
Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: evtricity on February 08, 2015, 03:39:19 AM
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Over the last few weeks I've been trying to eke out some extra performance improvements from my 2014 Zero SR for use on both the road and the track.
Having recently acquired the Sevcon software and CAN adapter to modify the Sevcon Gen 4 Size 6 motor controller, a multitude of options have opened up to tweak the bike's performance. While many Zero owners have trodden this path before me I thought I would post some of the changes to:
- give everyone some more insight into the out of the box torque settings of a Zero SR;
- highlight opportunities to improve performance; and
- compare notes with those who have made similar tweaks to improve on what is already a high performance naked bike
Torque curves:
The diagram at the end of the post shows the standard Zero SR 2014 torque curves as set on the Sevcon controller.
The key highlights are 100% torque from 0 rpm and a tapering of that torque beyond 2350rpm (default motor max is 6,000rpm). I asked some forum members about what would happen if I increased these settings and was told to watch out for two things - motor cutouts and to stay within the 6,000rpm limit. I was also told that field weakening limits motor performance as rpm increases and so I can't be like a kid playing with his Dad's graphic equaliser and put everything up to the max!
While I don't have a torque curve diagram for the actual Zero SR motor, I think the one for a Remy 250-90 (see bottom of past) is a good example of how a similar motor's torque would reduce as rpm's increase (presumably suffering the same field weakening as my SR). The gradual reduction for the Remy made me think that the Zero could handle a gradual reduction rather than the steep reduction set on the stock motor.
Looking at the two curves together it seemed to me that there was an opportunity to increase the SR's torque at higher rpm without reaching the motor's limits which would result in motor cutouts. After some trial and error on the road and recent testing on the track, I have been able to successfully increase torque by 30Nm @ 4680 rpm and by 45Nm @ 5320 rpm as shown in the updated torque curve at the bottom of this post.
In my trials I also tried to increase the mid-range torque @ 3,590 rpm but when I moved from 155Nm to 165Nm I got cutouts so left it at the 155Nm.
I think I've made some small but important performance improvements and the bike now accelerates much better at high rpm (which was particularly useful when I'd lowered the gearing in the successful search for wheelies and reduced the max speed to 135kph). I think there may be a few more Nm I could eke out in the higher rpm range and I'll try that in the coming weeks and update this thread accordingly.
On the opposite end of the spectrum, I've also learnt a lot about improving the stopping performance of my SR and you read more on that in my "powerful regen" post.
Keen to hear others success in tweaking their Zero's performance and any questions you may have around the changes I have made.
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Thats pretty interesting. I have a SR powertrain in my R6, while already fast, it would be cool to see how the limits may be pushed. I'll look into giving this a try.
Also the Remy motor is not a good comparison for field weakening. The Remy is an IPM (internal permanent magnet) motor and the Zero is a SMPM (surface mount permanent magnet). Basically the remy as more reluctance torque capabilities which allows the field weakening capabilities to be greatly enhanced from my understanding.
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Would you care to share the weight of your R6 with SR drive combination and the size battery you are using?
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Somewhere between 370-390lbs plus rider. 6kWh of Nissan Leaf cells.
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well done
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First of all, props for putting out all this info dgh853!
Interesting that the stock torque settings are 100% from 0 RPM. There have been numerous posts relating to the lack of off-the-line (until ~20-30 mph) pull for a bike that puts out 106 ft lbs of torque, some have purported that the sevcon settings must have been detuned to prevent snapping of the belt and/or unwanted wheelies. This seems to put that to rest but still leaves open the question as to why the SR can't wheelie with all that torque... (motor design, battery discharge limitation, weight distribution???)
Have you found any settings in the controller that would allow for traction control? That and the variable regen lever you posted would be great aftermarket features!
I'd love to start modding my bike (I just got a 15 SR) but I don't want to void the warranty so I've got a couple of years, in the meanwhile learning and accumulating the tools that I'll need.
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There have been numerous posts relating to the lack of off-the-line (until ~20-30 mph) pull for a bike that puts out 106 ft lbs of torque, some have purported that the sevcon settings must have been detuned to prevent snapping of the belt and/or unwanted wheelies. This seems to put that to rest but still leaves open the question as to why the SR can't wheelie with all that torque... (motor design, battery discharge limitation, weight distribution???)
I was one of the chief instigators of that discussion, and I think I've finally figured it out, at least to my satisfaction. The key is torque multiplication, which is why ICE vehicles have gearboxes in the first place.
When an ICE vehicle is run on a dyno, they rarely run torque and horsepower curves in all gears. It would just be repetitive and give no new information. Instead, they typically put the vehicle in top gear, and run the curves only once. That doesn't matter for horsepower, but it DOES matter for torque, because a lower gear gives higher torque multiplication. So when, for instance, they say that a Hayabusa peaks at 100 ft-lbs of torque, that's in top gear. I looked up the gear ratios for the Hayabusa, and first gear on that bike is 2.6 times higher numerically than top gear. So when a Hayabusa is in first gear, it's not putting 100 ft-lbs of torque on the pavement, it's putting down 260 ft-lbs. The SR has no gearbox, so its 106 ft-lbs of torque is what you get, period. That explains why other bikes may have wheelie and wheelspin issues our bikes don't have, even though many other bikes use much wider tires.
Of course, there are other issues involved -- smoothness of power delivery on the EV, instant throttle response, no time lost to shifting, etc., but the upshot is that the gearbox on the ICE vehicle does exactly what it's supposed to do, it multiplies the torque available at low road speeds.
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That is a great explanation and analysis, Doug. :)
No mater what the starting torque is, your typical street EV rider has a good chance of beating an IC rider off of the line. While your EV might have less starting torque, not having to rev the motor and slowly let out the clutch to prevent a scary wheel spin or a wheelie, really makes a difference. Anyone riding an EV can just open up the throttle and take off as fast as the bike will go, without needing the experience and skill of feathering the clutch properly. That is a real plus for any rider, especially a new rider. :) The gearbox-loving crowd might complain that takes away the challenge of owning a motorcycle and being a real motorcyclist, but I say that direct-drive is more likely to interest and increase motorcycle sales to new riders and I base my claim on the number of automatic transmission cars sales, compared with manual-transmission car sales.
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It's actually putting down more than that; besides the transmission gearing, you also have the ratio between the output sprocket and the rear wheel sprocket, assuming chain or belt drive.
The Zero SR has a 30 tooth front, 132 tooth rear sprocket. That means the motor is turning 4.4x as fast as the rear wheel, and also wheel torque is 4.4x as high as motor torque. So 106 ft-lb at the motor will be 466 ft-lb at the rear wheel. Of course, as vehicle speed and wheel RPM increases, motor RPM will increase as well; and around 2350 RPM (motor) = 39.2 mph the torque will start to fall off.
Compare that to a conventional motorcycle, which has a primary drive ratio, transmission gear ratio, and final drive ratio which all amplify torque. A Hayabusa has a 1.596 primary drive ratio, 2.352 final drive ratio, and in 1st gear has a 2.615 ratio. Multiply all of those up for a 9.82x multiplier.
At a 10 mph roll, for example, the Hayabusa rear wheel will be turning at about 137 RPM and the motor will be turning at about 1345 RPM. Most dyno plots for the motor don't go down that low, but the trend indicates it will be producing about 60 ft-lb at the motor at that RPM. With all of the multiplicative effects of the transmission, it should then produce about 590 ft-lb at the rear wheel.
Brammo Empulse R for reference has about 650 ft-lb in 1st gear.
All of that is ignoring the drag effects of the transmission and drive systems (gearbox will be higher drag), vehicle mass, clutch and flywheel effects, etc.
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@protomech: You're right, of course, that all gearing ratios between the motor and drive (rear) wheel count. I was really just pointing out that there's a CHANGE in gear ratio possible on ICE bikes that never happens on our direct-geared bikes. Effectively, I was assuming that the top-gear ratios were about the same, and discussing why that means more low-road-speed torque for the ICE bike. In reality, I'd be willing to bet that's not too far off -- the SR tops out about 6000 rpm just over 100 mph, where the Hayabusa is geared for considerably higher top speed but turns a lot faster too.
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Some reference on those numbers, not here to fight, just giving some additional information on the different torque numbers. Both with transmission and without have their benefits... I just wanted to share my calculations for you guys to use as needed.
Brammo Empulse R:
http://electricmotorcycleforum.com/boards/index.php?topic=3871.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3871.0)
Torque at rear axle:
1st: 882.09 N-m or 650.60 ft-lbs
2nd:721.33 N-m or 532.03 ft-lbs
3rd: 597.68 N-m or 440.83 ft-lbs
4th: 507.00 N-m or 373.94 ft-lbs
5th: 428.68 N-m or 316.18 ft-lbs
6th: 391.58 N-m or 288.81 ft-lbs
Rear tire peak force at rubber:
1st: 2760 N or 620.47 lbf
2nd: 2258 N or 507.62 lbf
3rd: 1871 N or 420.62 lbf
4th: 1587 N or 356.77 lbf
5th: 1342 N or 301.69 lbf
6th: 1226 N or 275.62 lbf
Zero SR:
http://electricmotorcycleforum.com/boards/index.php?topic=3872.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3872.0)
Torque at rear axle: 633.6 N-m or 467.32 ft-lbs
Rear tire peak force at rubber: 1983 N or 445.80 lbf
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There have been numerous posts relating to the lack of off-the-line (until ~20-30 mph) pull for a bike that puts out 106 ft lbs of torque, some have purported that the sevcon settings must have been detuned to prevent snapping of the belt and/or unwanted wheelies. This seems to put that to rest but still leaves open the question as to why the SR can't wheelie with all that torque... (motor design, battery discharge limitation, weight distribution???)
I was one of the chief instigators of that discussion, and I think I've finally figured it out, at least to my satisfaction. The key is torque multiplication, which is why ICE vehicles have gearboxes in the first place.
I also posted that I thought the power was dialed down when starting. I was even told that by a Zero tech so I wonder where he got his info. We get so locked in to the 106 ft lb number that a simple concept like gear reduction and torque at the rear wheel gets forgotten. So, I need a gearbox to wheelie? Darn!
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So, I need a gearbox to wheelie? Darn!
Nope, you just need MORE TORQUE! If you want to wheelie or create wheelspin, you just need torque, whether you get it from lower gearing or however.
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The SR will wheelie if you run lower gearing - my 15 tooth front and 80 tooth rear sprockets will lift the front wheel on uphill grades sitting back on the seat!
Unfortunately the Sevcon controller does not support traction control although there are some settings about ramp rates for acceleration.
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Yes, good information. Remember too, ICE bikes don't have max. torque at 0 rpms, but they can have max torque at 0 mph by reving the engine and popping the clutch, so really ICE bikes have all their torque potentially available from takeoff just like an electric bike. With a clutch wheelie, you can even be moving in 1st or 2nd gear typically, then briefly pull the clutch to get the revs higher and pop the clutch again for a second or 3rd wheelie. The revs increase so rapidly when you do this that it might as well be instantaneous.
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Fantastic data and effort dgh853. I can see a trip over to your place coming up soon for some enhancements on my DS!
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on the gen 4 size 4 you can tun the same what are the limit someone know?
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on the gen 4 size 4 you can tun the same what are the limit someone know?
The Gen4 data sheet at http://www.sevcon.com/media/2461/Gen4%20Aug%202013%20web.pdf (http://www.sevcon.com/media/2461/Gen4%20Aug%202013%20web.pdf) has the amp limits for both the size 4 and size 6 contollers so you can compare.
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hi, on my dvt i do not have the power limit, do you have specale dvt file?
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If you click on power maps there should be 3 items appearing. Select the first one and that should bring up the torque limit at each rpm as per the torque curve screenshot at the start of this thread.
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Brammo Empulse R:
http://electricmotorcycleforum.com/boards/index.php?topic=3871.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3871.0)
Torque at rear axle:
1st: 882.09 N-m or 650.60 ft-lbs
2nd:721.33 N-m or 532.03 ft-lbs
3rd: 597.68 N-m or 440.83 ft-lbs
4th: 507.00 N-m or 373.94 ft-lbs
5th: 428.68 N-m or 316.18 ft-lbs
6th: 391.58 N-m or 288.81 ft-lbs
Zero SR:
http://electricmotorcycleforum.com/boards/index.php?topic=3872.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3872.0)
Torque at rear axle: 633.6 N-m or 467.32 ft-lbs
So an SR is equivalent to an Empulse R in 3rd and a Zero S is equivalent to a 5th gear?
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Zero SR is 637 Nm
Zero S is 434 Nm
So yes, that's about right.
With a rider the Zero ZF12.5 bikes weigh about 10% less than the Empulse, so the effect will be closer to matching acceleration in 2nd gear with the SR and 4th gear with the S.
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Yeah, they'll pretty much be the same at those different gears with the Brammo.... and here's the math to back up Protomech (because I'm bored at work), ignoring road resistance/aero. Yay math!!!!
Zero SR 12.5 is:
188kg (~12% less weight than the Empulse)
1983 N at the tire
(http://electricmotorcycleforum.com/boards/index.php?topic=3872.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3872.0))
Zero S 12.5 is:
185kg (~13% less weight than the Empulse)
1353 N at the tire
Brammo is:
213kg
1st: 2760 N at the tire
2nd: 2258 N at the tire
3rd: 1871 N at the tire
4th: 1587 N at the tire
5th: 1342 N at the tire
6th: 1226 N at the tire
(http://electricmotorcycleforum.com/boards/index.php?topic=3871.0 (http://electricmotorcycleforum.com/boards/index.php?topic=3871.0))
Lets say a rider like myself, ~90kg rides all three bikes. We know F = m*a. We want to know a, so a=F/m. Total Brammo weight is 213+90=303kg. Total Zero SR 12.5 weight is 188+90=278kg. Total Zero S 12.5 weight is 185+90=275kg.
Zero SR acceleration:
1983N/278kg = 7.13m/s^2
Zero S acceleration:
1353N/275kg=4.92m/s^2
Brammo acceleration:
2760N/303kg=9.11m/s^2
2258N/303kg=7.45m/s^2
1871N/303kg=6.18m/s^2
1587N/303kg=5.24m/s^2
1342N/303kg=4.43m/s^2
1226N/303kg=4.05m/s^2
Just going off those numbers, Brammo is only 6.5% quicker than a Zero S if the Brammo was left in 4th gear. Likewise, the Brammo is only 4.5% quicker than a Zero SR if the Brammo was left in 2nd. That's a pretty close acceleration between the bikes with the Brammo in 2nd and 4th.
What we don't have here is the torque curve of each motor (I kinda wish we had exact curves, they'd be fun to look at). The torques above are max torque. Torque rolls off at higher RPM, so this really only tells you what the max torque from stop/low RPM would be. Over 4kRPM, I'm not sure what each motor would deliver for torque. Its something only a Dyno (or some torque curves) would tell us.
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Looking at the two curves together it seemed to me that there was an opportunity to increase the SR's torque at higher rpm without reaching the motor's limits which would result in motor cutouts. After some trial and error on the road and recent testing on the track, I have been able to successfully increase torque by 30Nm @ 4680 rpm and by 45Nm @ 5320 rpm as shown in the updated torque curve at the bottom of this post.
Increasing 45Nm @ 5320 rpm is an increase of 25 kW!
Are you sure?
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I can confirm those are the actual before and after Nm values in the controller.
I've increased the torque by 25% (45/180) for that rpm range.
I don't believe that correlates to 25kW as the changes are to motor torque not actual power.
Bear in mind that for the SR, the max power is 50kW and 144Nm.
Others who understand the link between torque and power can comment here but if there was a direct correlation between the two then the increase would correlate to 25% of the maximum power of 50kW or 12.5kW.
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The way to calc power is this:
Power (kW) = Torque (Nm) * rpm* 2*PI/60
So, 45 Nm @ 5320 rpm is 25 kW
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The key highlights are 100% torque from 0 rpm and a tapering of that torque beyond 2350rpm (default motor max is 6,000rpm). I asked some forum members about what would happen if I increased these settings and was told to watch out for two things - motor cutouts and to stay within the 6,000rpm limit. I was also told that field weakening limits motor performance as rpm increases and so I can't be like a kid playing with his Dad's graphic equaliser and put everything up to the max!
Can anyone explain the technical background why the torque needs to get lower at higher rpm? Why does the motor cut out if the tourque is set too high?
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Mechanical power is product of torque and rpm (see above)
Electric power is V * A
If 160Nm was constant until 6000rpm the motor would produce 100kW.
If the motor is 90% efficient, that would mean 10kW of heat and the Zero motor wouldn't be able to dissipate that amount of heat...
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I have fastest zero on paper???? No way..... I know there are quicker in here. Who owns that 757 tandem bike? No he got me beat power to weight
Sr. tune vs gutted fx frame 8)
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Do you mean Death bike 7.0?
The owner is liveforphysics, in the endless-sphere forum
But that is, supposedly, a bicycle, not a motorcycle
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I suppose, given who the maker is, its "technically" a Zero... ;)
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Do you mean Death bike 7.0?
The owner is liveforphysics, in the endless-sphere forum
But that is, supposedly, a bicycle, not a motorcycle
;D supposedly, a bicycle....... LOL
Ya he's got a pretty mean 1/4 mile time if I dragged my bike that is the number I would chase; I would have to use high speed gearing, (I beleive) because I need more top end
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dgh,
have you experimented at all with change the speed (RPM) values for a give torque to find where the limits might lie? Just curious.
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I haven't changed the rpm per se but experimented with different torque levels for each rpm level. Don't see a problem with trying different rpm points but I suspect the Zero engineers know the approx max rpm at which you can run full torque without cutouts so be mindful of pushing the 180Nm torque higher
As noted earlier in this thread you can push up the torque at higher rpm to a degree but if you push too far the motor will cut out momentarily which is not fun when you've got the bike leaned over coming out of a corner.
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I haven't changed the rpm per se but experimented with different torque levels for each rpm level. Don't see a problem with trying different rpm points but I suspect the Zero engineers know the approx max rpm at which you can run full torque without cutouts so be mindful of pushing the 180Nm torque higher
As noted earlier in this thread you can push up the torque at higher rpm to a degree but if you push too far the motor will cut out momentarily which is not fun when you've got the bike leaned over coming out of a corner.
I ahve experienced these cut out on my modified 2012 that use the 2013 75-7 motor... i have played with many parameters in the DVT but i forgot to reconsider the torque curve i have set ... lol.. this could be the reason of the cut out .. lol
Doc
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I haven't changed the rpm per se but experimented with different torque levels for each rpm level. Don't see a problem with trying different rpm points but I suspect the Zero engineers know the approx max rpm at which you can run full torque without cutouts so be mindful of pushing the 180Nm torque higher
As noted earlier in this thread you can push up the torque at higher rpm to a degree but if you push too far the motor will cut out momentarily which is not fun when you've got the bike leaned over coming out of a corner.
Cool, yea I currently have your most up to date settings on the torque values. But looking at the curve for torque it seems as if it should be smoother. If I play with the settings I will update this thread. My test would be on the streets, so less likely to be leaned full over.
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Keen to see how it goes for you. I took the bike out to Sydney Motorsport Park yesterday with no cutouts at those torque settings. If you're pushing the bike harder you'll definitely need to consider motor cooling options with the higher torque settings.
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This is electrical power, not actual power
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dgh853, I have noticed that the cutout seem to stop on my 2012 S 75-7 when motor is hot or after my battery is lower voltage, maybe reaching 50% or less SOC...
I guess that the torqure at high rpm that might be set too high on my setting can cause less cut out due to the lower power my battery have at lower SOC ( lower voltage but same amp limiting) = lower power..
Do you think it make sense?
Doc
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Very interesting observation Doc.
Cutouts do seem more prevalent on a cooler motor and with a higher battery voltage. I have had cutouts on the first lap of a track day but then go through the rest of the day with no cutouts. I can understand less cutouts at lower voltage but I can't see how motor temperature could make a difference.
David
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David, The motor winding when it is hot will have higher resistance meaning it might draw less current from the controller when it is not in current limiting mode at higher rpm ;)
I definitively need to correct mt torque vs speed map!.. but i have to buy a IXXAT as my local Zero dealer is at 2 hours run every time i need it...
There is a not really honnest person selling one for 600$ on ebay !! damn it! this thing when it was availlable brand new was priced 400$ !... lol
Doc
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I just picked up a IXXAT but it has not arrived yet. Maybe sometime down the road a bit I can loan it out. ;)
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If you are thinking about "performance tuning" your EV, you might want to check out this story:
https://rideapart.com/articles/will-u-s-copyright-office-decision-short-circuit-altering-bikes-software
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modifying your software is no different than modifying your ICE bike or car. If Suzuki tried to sue someone for modifying one of their bikes they would be laughed out of the court house. I didn't sign any wavers, NDA's, or agreements that I would not mod my bike. The only thing that was in the manual from the manufacture was that non approved mods could void the warranty. Good luck with that issue.
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They are arguing that its a violation of the DMCA, which is just ludicrous, but then a lot of stupidity had been justified using that act...
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I thought violating the DMCA required having to thwart some kind of password protection or encryption put in place by the vendor.
If it's open without any kind of protection, why would the DMCA have any bearing?
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if you can access the sevcon settings and change them without a password then 2 things: 1 you are not entering a passwords thus not doing anything that is shadie or wrong. 2 That is Sevcons software not Zero's so they can't claim DMCA on something that is not theirs.
With the MBB that may be a little less cut and dry as you do need to know or defeat passwords. That being said, this is on something that you own and is no longer owned by the manufacture. As long as you are not redistributing anything then you are not breaking any DMCA laws.
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You need to be in pass word level 4 (of 5) to make critical changes in the Sevcon settings.
If you use the Sevcon SW it will automatical use the standart PW. If you use CAN manually you need to know log in with the PW!
Also the MBB and BMS has PW levels.
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Over the last few weeks I've been trying to eke out some extra performance improvements from my 2014 Zero SR for use on both the road and the track.
Having recently acquired the Sevcon software and CAN adapter to modify the Sevcon Gen 4 Size 6 motor controller, a multitude of options have opened up to tweak the bike's performance. While many Zero owners have trodden this path before me I thought I would post some of the changes to:
- give everyone some more insight into the out of the box torque settings of a Zero SR;
- highlight opportunities to improve performance; and
- compare notes with those who have made similar tweaks to improve on what is already a high performance naked bike
Torque curves:
The diagram at the end of the post shows the standard Zero SR 2014 torque curves as set on the Sevcon controller.
The key highlights are 100% torque from 0 rpm and a tapering of that torque beyond 2350rpm (default motor max is 6,000rpm). I asked some forum members about what would happen if I increased these settings and was told to watch out for two things - motor cutouts and to stay within the 6,000rpm limit. I was also told that field weakening limits motor performance as rpm increases and so I can't be like a kid playing with his Dad's graphic equaliser and put everything up to the max!
While I don't have a torque curve diagram for the actual Zero SR motor, I think the one for a Remy 250-90 (see bottom of past) is a good example of how a similar motor's torque would reduce as rpm's increase (presumably suffering the same field weakening as my SR). The gradual reduction for the Remy made me think that the Zero could handle a gradual reduction rather than the steep reduction set on the stock motor.
Looking at the two curves together it seemed to me that there was an opportunity to increase the SR's torque at higher rpm without reaching the motor's limits which would result in motor cutouts. After some trial and error on the road and recent testing on the track, I have been able to successfully increase torque by 30Nm @ 4680 rpm and by 45Nm @ 5320 rpm as shown in the updated torque curve at the bottom of this post.
In my trials I also tried to increase the mid-range torque @ 3,590 rpm but when I moved from 155Nm to 165Nm I got cutouts so left it at the 155Nm.
I think I've made some small but important performance improvements and the bike now accelerates much better at high rpm (which was particularly useful when I'd lowered the gearing in the successful search for wheelies and reduced the max speed to 135kph). I think there may be a few more Nm I could eke out in the higher rpm range and I'll try that in the coming weeks and update this thread accordingly.
On the opposite end of the spectrum, I've also learnt a lot about improving the stopping performance of my SR and you read more on that in my "powerful regen" post.
Keen to hear others success in tweaking their Zero's performance and any questions you may have around the changes I have made.
Evtricity. How is the bike going with the new torque settings?
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Very good.
I have been running these settings for many months. The bike accelerates from 0-100kph in 4.0 seconds with 80kg rider on 17/66 gearing that tops out at 184kph at 6,000rpm.
The motor can cut out momentarily under hard acceleration in the first minute or two of the first session of a track day when the battery and motor are cold. This never occurs later on the day so have left the settings as is. I could lower the torque a little to remove this cutout but may trade off some acceleration when the battery/motor is warmer. The cutout occurs just under 3,000 rpm usually and I'm guessing that is when the motor's torque limit starts to fall away from peak.
The increased torque settings and gearing do overheat the motor faster but it's worth it for the few minutes of better performance. I would love to use the new IPM motor and run higher rpm for more top speed or more likely in conjunction with lower gearing for better acceleration and the same top speed. The IPM will likely overheat as well just not as soon.
Sent from my LG-D855 using Tapatalk
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Just a thought, but how about adapting a tire warmer to pre-heat your batteries and motor?
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Maybe! I just hold it a little less than full throttle when accelerating under 120kph (for the first 3-4 minutes of the first session) to avoid the problem. If I'm racing I do 3-4 90% throttle accelerations on the warm up lap and usually no problem pinning it on the start line and for the rest of the race.
Sent from my LG-D855 using Tapatalk
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This is great information, thanks for sharing evtricity! I'm sure just about everybody on this site is as curious and excited as I am to find out how much of this can be applied to the 2016 Zero lineup using the IPM motor. I think there is going to be a lot of new learning that takes place when those things get into the hands of hot rodders!
In the spirit of spreading knowledge....
The key highlights are 100% torque from 0 rpm and a tapering of that torque beyond 2350rpm (default motor max is 6,000rpm). I asked some forum members about what would happen if I increased these settings and was told to watch out for two things - motor cutouts and to stay within the 6,000rpm limit. I was also told that field weakening limits motor performance as rpm increases and so I can't be like a kid playing with his Dad's graphic equaliser and put everything up to the max!
Back EMF is your enemy, not field weakening. Field weakening is a technique that can be used to overcome back EMF. The EMF created by the spinning magnets generates a voltage in the stator coils. This voltage cancels out the voltage being applied by the controller. This is referred to as back EMF because when you apply a voltage to the stator coils the current creates a magnetic field that spins the magnets/rotors and the spinning magnets then generate a magnetic field BACK which opposes the magnetic field created by the current in the stator coils.
Volts from controller - volts from back EMF = working voltage.
At low RPM the voltage from the controller is high and volts from back EMF is low so you have lots of working voltage. As RPM increases the working voltage approaches zero.
Zero working voltage = zero torque
Basically, the harder you push the more it pushes back. But field weakening limits the amount it pushes back.
Field weakening basically allows you to keep positive working voltage at high RPM. Field weakening can be applied to SPM motors but requires LOTS of current and you need to have a better cooling solution because of the amount of heat generated.
IPM motors are perfect candidates for field weakening and it can be done at the power levels required at lower RPM. As a result IPM motors can hit much higher RPM without additional cooling required
2015 Zero SR Final drive ratio = 30/132 and should hit 101.9 mph at 6100 RPM (Zero claims 102 mph top speed)
2016 Zero SR Final drive ratio = 30/130 and should hit 101.8 mph at 6000 RPM (again a claimed top speed of 102 mph)
2015 SR uses an SPM and 2016 SR uses an IPM. Based on the ratio of sustained speed to top speed used on previous Zero's, since the 2016 SR can sustain 95 mph it should be able to hit a top speed of 114 mph
2015 SR top speed/sustained speed = 102/85 = 1.2.
1.2 * 95 mph = 114 mph (113.7 mph at 6750 RPM using 30/130 gearing)
Yet the 2016 SR is limited to 102 mph which is only about 6000 RPM (101.8 mph) with the 2016 gearing. hmmm :-\
When you say "cutouts" what do you mean? Like you get when you hit temp limit?
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Thanks for the electrical motor 101!
The cutouts I mention are a momentary (just under one second) complete loss of motor power. It's the equivalent of chopping the throttle instantly.
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Thanks for the electrical motor 101!
The cutouts I mention are a momentary (just under one second) complete loss of motor power. It's the equivalent of chopping the throttle instantly.
Do you know if it is being caused by the controller cutting power to the motor or if the controller is applying voltage to the motor but the motor is providing output power?
Have you done tests on a dyno to see how much more torque is being produced at the wheel by making the torque setting changes?
Heat affects the strength of the magnets. They get weaker when they are hotter. They will return to full strength when they cool unless they have exceeded the temp were permanent demagnetization occurs.
Dyno tests might reveal that you are actually better off with the lower settings in the scenarios where you get cutouts at lower temps but not after heating up. Or it might reveal that there are other areas on the curve where you can bump up the settings and only suffer cutouts while temps are low but gain torque once things heat up. More data is needed to find out the objective answer.
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Very good.
I have been running these settings for many months. The bike accelerates from 0-100kph in 4.0 seconds with 80kg rider on 17/66 gearing that tops out at 184kph at 6,000rpm.
The motor can cut out momentarily under hard acceleration in the first minute or two of the first session of a track day when the battery and motor are cold. This never occurs later on the day so have left the settings as is. I could lower the torque a little to remove this cutout but may trade off some acceleration when the battery/motor is warmer. The cutout occurs just under 3,000 rpm usually and I'm guessing that is when the motor's torque limit starts to fall away from peak.
The increased torque settings and gearing do overheat the motor faster but it's worth it for the few minutes of better performance. I would love to use the new IPM motor and run higher rpm for more top speed or more likely in conjunction with lower gearing for better acceleration and the same top speed. The IPM will likely overheat as well just not as soon.
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This is great news evtricity, great job!
I'm a bit confused on the cut-outs comment.
When you made the first modification -posted std. and modified torque graphs- there were no torque changes on the sub 3500 rpm range from my understanding, so there should not be cut-outs…have you made more changes?
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Have you ever looked at the draw side? You might be hitting the cutbacks to protect the battery just a thought
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The motor can cut out momentarily under hard acceleration in the first minute or two of the first session of a track day when the battery and motor are cold.
Sorry for the thread hijack, but can you tell me more about these cut outs? This sounds suspiciously like something I have experienced a couple of times in my stock 15SR - early in my commute during heavy acceleration the engine "stutters". It's only happened a few times, but it is worrying.
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My 2014SR does not cut-out, but it becomes a bit "weak" from 60mph-on specially when the motor is cold (I guess this may have something to do with the internal windings resistance, as when it becomes warmer it is not that bad...but not sure)
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I'm not certain on what is causing the motor cutouts. I actually had cutouts although very rarely with the stock settings before I modified the SR at all.
The cutouts are a brief loss of power. You could call it a stutter I suppose as the power comes back on pretty quickly. Not to be confused with the metallic noise/vibration of the SR under hard acceleration.
When I did change the settings with increased torque, my testing was done on the road and the motor and battery were warm. Under that scenario I found settings that would not cutout when the bike was warm. It was later on, on the track when I pinned it on the first lap or two at the start of the day when motor / battery were cold that I got the cutouts.
I could get the bike dynoed to confirm different torque settings but I can only effectively do a cold motor / battery test once per day. In essence the cutout problem is difficult to replicate as it only occurs when motor /battery are cold with the current settings.
I have effectively set the torque settings to avoid cutouts when the motor is warm.
One thing that I also had forgotten about is that I now have a higher gear on the bike than stock. I'm not sure that was the case when I first tested the higher torque settings. That would effectively increase the duration of high loads on the motor and increase the likelihood of cutouts.
Thanks for all the questions. It's good to think harder about a problem to understand the cause and overcome it.
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In the video at https://www.youtube.com/watch?v=0D5tlkY0sHU (https://www.youtube.com/watch?v=0D5tlkY0sHU) you can hear the cutout. It occurs 10 seconds in. It's only momentary and the power comes back on.
Hope this helps explain the cutout.
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Not to be confused with the metallic noise/vibration of the SR under hard acceleration.
Is this the same noise I would hear heading up a very steep hill under acceleration?
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Probably. Listen to the video I just posted right from the start of the race and you will hear the sound of the SR motor under full acceleration.
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Well heck, that doesn't sound anything like anything I've ever heard of before :)
I've got a phone mount, I should try recording it. Was that inside your windshield?
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Yes, behind the windscreen. There is also a loud white noise even before the bike leaves the start line. That is the electric ducted fan that forces air through the motor for cooling.
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The best is when you overtook the rider ahead of you 2'45" ;)
He's got a damn powerful bike :o
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Volts from controller - volts from back EMF = working voltage.
At low RPM the voltage from the controller is high and volts from back EMF is low so you have lots of working voltage. As RPM increases the working voltage approaches zero.
Zero working voltage = zero torque
Basically, the harder you push the more it pushes back. But field weakening limits the amount it pushes back.
Field weakening basically allows you to keep positive working voltage at high RPM. Field weakening can be applied to SPM motors but requires LOTS of current and you need to have a better cooling solution because of the amount of heat generated.
IPM motors are perfect candidates for field weakening and it can be done at the power levels required at lower RPM. As a result IPM motors can hit much higher RPM without additional cooling required
Great info Mrwilsn, thanks!
Can you point to some books and/or papers online about field weakning?
IPM = internal mounted PM rotor and SPM = surface mounted PM rotor?
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I would like to modify the torque settings as described, can they be modified using a sevcon hand held calibrator or do you need the pc program? Ive been trying to rent the hand held from Thunderstruck, but the last person to borrow it, will not return it. Therefore I would need to buy one at $450,ugh. What is the best way to go. Ive got a dongle but without the passwords it doesnt go far.
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What dongle do you have?
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Purchased Dongle from Hollywood Electric.
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Purchased Dongle from Hollywood Electric.
I believe that the dongles only allows you to access the Main Bike Board (MBB). You need an IXXAT USB to CAN adaptor and Sevcon PC software to change torque curves on the Sevcon controller on a Zero.
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Will the sevcon handheld calibrator work?
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The handheld calibrator plugs directly into the controller or the obd2 port. Im not sure what the capabilities are, it note that it is "suitable for fine tuning an existing setup" whatever that means.
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I'm not aware of anyone using that device to configure a Zero's torque curve. Perhaps it could be used to upload/flash a Sevcon configuration file however the Zero OBD port uses an uncommon pin format which I doubt this hand-held unit would work with.
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is the controller running off is own program or is it running off zeros?
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Zero have heavily customised the Sevcon configuration to work with their motors. That includes passing parameters between the Sevcon and MBB via the CANBUS.
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What do the adapter and software sell for?Does the dongle work with the programmer? Is that what doctorbass has for sale?
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I see now that the adapters were on eBay hum