E-Fun- Experiences and development of an PRC EV Vehicle manufacturer, latest products and developments

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marcopolo
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E-Fun- Experiences and development of an PRC EV Vehicle manufacturer, latest products and developments

In response to the very interesting offer by leading PRC EV manufacturer, E-Fun to contribute to the forum as a result of the somewhat controversial thread 'E-fun or Mountain Chen'. I thought it would be useful to create a separate thread where forum members could create a dialogue with this manufacturer.

E-Fun has kindly offered to discuss a wide range of commentary, from product technical details to import export problems. E-fun has expressed a real interest in benefiting from the vast technical and practical experience forum members possess. Here is a chance to talk directly to an EV maker. (John, we already value your contribution).

Amoyee Chen, we appreciate that it is not always possible for your staff to post in English, but if you feel more comfortable, please feel free to send me your material in Chinese, and I will post a (fairly) accurate translation.

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear marcopolo

Thanks for your trust and interesting in EFun,may I konw your mail box ,so that i can PM you directly?

Amoyee Chen

procrastination inc
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

thanks for direct the open contact.

I hope this is the new trend for customer relations. It would be nice to see other manufacturers having open, collaborative dialogue with current and future customers

congratulations, respect and who is your australian distributor? :)

wookey
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

I've had a very useful discussion with E-fun regarding the E-fun A, sold in the UK as the Sakura S50.

I posted a summary of that discussion on the UK forum:
http://electricmotoring.forumup.co.uk/viewtopic.php?p=2053&mforum=electricmotoring#2053

Wookey
Sakura s50 (Efun A)

myocardia
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear marcopolo

Thanks for your trust and interesting in EFun,may I konw your mail box ,so that i can PM you directly?

Amoyee Chen

Hi, Amoyee. Nearly all forum software, including the software used here at VisforVoltage allows you to just left-click on any person's name whom you wish to send a PM, and one of the options will be to send them a PM. That works for anyone registered here. I realize that you were asking marcopolo for his private e-mail address, but sending PM's is very, very easy and is sometimes considered the best option (by some members of some forums). If you (or any other members) need screenshots of the process of sending a PM through this forum, just let me know, and I can provide them.

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Casually,I found website http://www.zelectricvehicle.com/12.html that referred to EFUN products.

Third - The motor. Our motor makes more torque at less amps than any other known competitor. We obtain our torque at 70 amps to 80 amps.(model dependent) Others use far more amps to get the same torque. The higher amps of the competitors reduces range. A quick way to guage the motor effectiveness of a hub motor is to simply look at the diameter of the motor. The larger the diameter, the more torque at equal volts/amps. Our motor fills the wheel right to the rim. All others are much smaller in diameter with visible "spokes" or area between the motor and the rim like the EFun or Liberty (renamed ZAP and EFun) bikes.

Yes,I agree the higher amps not only reduce ranges,but also hurt batteries cycle life if more than 2C discharging currents.For example, consuming current 80A at 40Ah cells and less 120A at 60Ah would be best.Only max 100A current limiting strictly in EFUN's 6000W controllers,then 85A,65A...in less power output.No one can doubt our powerful motors even EVD with heavy 5*50Ah lead acid batteries or 2008 Zapino with 65A/60V controller.Please see our website http://www.efun-ev.com/video/EFUN%20EVs%20climbing%20mountain.html

On the other hand,I oppugn why the diameter of the motor will make effect on torque?The same size 13'wheel arround it needs the equal torque,no matter how full rim motor or EFUN's separable motor and visible "spokes". We require it for airflow cooling and easy maintenance.More important is that our 6 phases motor and controller are comparative differ from other products in the world.They're build of distinctive materials and designs.So EFUN EV is unique.

Amoyee Chen

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Here are some conventional diagrams of our motor testing reports.What're difference between our motor/controller and other products?Please see the details in http://www.efun-ev.com/technology.asp

3000W testing report.JPG4000W testing report.JPG5000W testing report.JPG6000W testing report.JPGLCD instrusment.JPGactive BMS.JPG

Amoyee Chen

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Amoyee, torque is always a product of force times leverage at which the force is active. In our case the force is generated between coils and magnets. If the same magnets and coils are used for a 13 inch motor and for a 10 inch motor, the magnetic force they can create will be similar (this is highly simplified). But the leverage of the 13 inch motor will roughly be 13/2=7.5 inches, wheras the 10 inch motor will only have 5 inches of leverage to bring into the equation. This means the 13 inch motor could be capable of approximately 30% higher torque than the 10 inch motor simply due to it's higher leverage.
The downside is a smaller transmission ratio from motor to tire surface for the 13 inch motor, meaning top speed might not be as high as a 10 inch motor in 13 inch wheel could achieve.

However, if the 10 inch motor uses different coils, stronger magnets, smaller airgap between stator and magnets, etc. it could reach similar torque levels per A as a 13 inch motor with inferior coils, magnets, airgap etc.

Just for comparison, your brother's 13 inch 5/8kW motor reaches 150Nm max with 60A, where your smaller diameter 6000W would only produce around 111Nm judging from your measurement of 184Nm at 99A. Size DOES matter :-)

Oh, and another thing to ponder: Even though your winding system and 6 phases are quite unique, the quality of power control of your special controllers is miserable, it is more less either on or off and is in dire need of finer controllability. Power-PWM should be used in order to improve this. I once did a 40km test ride on your D4000Li 4kW scooter (Innoscooter) and my right hand hurt very badly for several days after that because I, with my hand, had to work hard at the throttle switching current on and off in order to keep all speeds below max more or less constant. The controller is supposed to do this work, and my hand should only have to tell the controller: I now want just 20% power in order to drive at 30km/h, or just 2% power to get out of my driveway, or 100% to take off full blast. When will your bikes finally be able to supply this fine controllabilty???

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Just for comparison, your brother's 13 inch 5/8kW motor reaches 150Nm max with 60A, where your smaller diameter 6000W would only produce around 111Nm judging from your measurement of 184Nm at 99A. Size DOES matter :-)

Dear MEroller,

If the 5/8kW motor reaches 150Nm,it would depend on a preestablished rpm in the hub motor(donnot care about its size) and its output power,not only amps.As you know,the motor winding arrangements are closely related to power performance. The higher rotating speed, the faster speed , and the smaller torque; The lower rotating speed, then the contrary.Our 6kW motor is designed at arround 1138 rpm for high speed 95km/h real road tested by GPS,and what about your Thunder 5kW? In addition,there are 24 cells in your battery pack that consumes more 14% output power than our 21 cells/pack in 6kW scooter while the same 60A output current,that makes torgue bigger.

When will your bikes finally be able to supply this fine controllabilty???

Yes,we had made great improvements in our controller that will seperate the current from 6-phase to 3-pahse. In flat road if you choose the 3-phase mode on the throttle,you will gain a smooth start and cruise at all speeds constantly. If you are driving on the slopes or highway,you can just press the 6-phase mode and accelerate like a rocket:-)

Amoyee Chen

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

If the 5/8kW motor reaches 150Nm,it would depend on a preestablished rpm in the hub motor(donnot care about its size) and its output power,not only amps.As you know,the motor winding arrangements are closely related to power performance. The higher rotating speed, the faster speed , and the smaller torque; The lower rotating speed, then the contrary.Our 6kW motor is designed at arround 1138 rpm for high speed 95km/h real road tested by GPS,and what about your Thunder 5kW?

You DO realize though that with an idle (as in NO power output whatsoever) rpm of 1138 you can only reach real 95km/h on a rather strong downhill gradient??? On such a slope my 5kW Thunder has reached real (GPS) 100km/h. But idle RPM is completely irrelevant for level road max speed. 95 real km/h on level road would require a power output of around 6300W at the rear wheel at around 1016rpm. My Thunder can go around 86 real km/h at ambient temp. above 20°C. I have not yet tried to calculate your 6000W motor's level road top speed, but I will attempt to do that in the coming days. And it won't be anywhere near real 95km/h...
Here are the vital statistics of the 13in 5kW Erider motor, they speak for themselves:
Erider_5kW_72V_80A.gif

When will your bikes finally be able to supply this fine controllabilty???

Yes,we had made great improvements in our controller that will seperate the current from 6-phase to 3-pahse. In flat road if you choose the 3-phase mode on the throttle,you will gain a smooth start and cruise at all speeds constantly. If you are driving on the slopes or highway,you can just press the 6-phase mode and accelerate like a rocket:-)

The rocket part is true, but it is either rocket or nothing, there is nothing in between. And it does not matter much if 6 or 3 phases are used, both have very similar startup performance but diverge with increasing speed. What I mean to say is portrayed in the following graph:
Efun_Controllability.gif
At a small throttle position I also want (and need) small power output from the controller, and at high throttle position I want high power output. It needn't necessarily be absolutely linear, but you get the idea. That 4kW Efun scooter I rode behaved like the red graph: There was a small power output only around the first degree or two of throttle pos, only to slam into full blast at 3 degrees. Even to keep 50km/h constant in 6phase mode I had to regularly back off the throttle and then add it again, on-off-on-off... You NEED to implement power-PWM control like Kelly and Sevcon do, just two steps are not usable in real traffic conditions!

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

You DO realize though that with an idle (as in NO power output whatsoever) rpm of 1138 you can only reach real 95km/h on a rather strong downhill gradient???

Dear MEroller,

No,we and our reverential XM5000Li users all tested our scooters at 60 MPH on the flat road.see http://visforvoltage.org/forum/8476-xm-5000li-one-year-later and http://visforvoltage.org/forum/5668-my-xm5000li-experience?page=7 .We updated 5kW to 6kW only for more torques(from 133Nm to 184Nm) and put the fans into cotrollers hidden in scooter's bodies.As a matter of fact,our 5kW motor's 1046 rpm have reached to 95km/h,not only in Mr.Johnny's theory:

Can someone please verify my calculations for RPM (1085) to km/h?:

Rim: 13 inch = 33,02cm
Tire: 130/60/13, 130 x 0,6 = 78mm x 2 = 15,6cm
Total Diameter: 33,02 + 15,6= 48,62cm
Radius: 48,62 x 3,14 = 152,67cm
Km/min: 0.0015267km x 1085RPM = 1,6564
Km/h: 1,6564 x 60= 99,38?

As for your vital statistics of the 13in 5kW Erider motor,150Nm at 18.4 rpm is invalid because of closing to locked rotor.Anyway I congratulate my brother's rapid progress in high 88% efficiency.That's very important if over 90% high efficiency,in 13' wheel,Km/min: 0.0015267km x 945RPM = 1,4427 Km/h: 1,4427 x 60= 86,56.Our 4kw motor(945RPM) will reach to 86km/h in theory. In fact,D4000Li 4kW scooter (20cells/pack in Innoscooter) has run at speed +80km/h,right?

Even to keep 50km/h constant in 6phase mode I had to regularly back off the throttle and then add it again, on-off-on-off...

Even in our 6kW scooters,you can easily keep 0~70km/h smoothly with our new controller's 3 phase mode.Big start-up current in 6phase mode was exactly powerful and can't be fine controllabilty.Wide power-PWM is needed for a solution.

Amoyee Chen

Johnny J
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear Amoyee!

If you read further in that thread you will find that the motor of the "Thunder 8KW" I have has an idle of 1326RPM and the scooter a GPS verified top speed on flat ground of 97km/h, so there is really a big difference in idle and "real" RPMs.

Best regards

Johnny

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

I can assure you that at 213 rpm there still are around 125Nm available at just 75A on the 13 inch Erider motor. Pump in 100A and it will deliver over 165Nm at that point.
High startup torque (almost locked rotor) is necessary to get started on steeper slopes, so it is extremely relevant what torque a hub motor can muster at locked rotor. Of course this must be carefully monitored and limited by the controller so no thermal or magnetic damage can be done at locked rotor, but if I am standing at a red light on a slope and it turns green I need that inital impulse to get going.

As Johnny wrote, idle rpm must be a lot higher than the expected max level speed of the bike. "Idle" means lazy, no mechanical power can be extracted. For top speed however a significant torque and thus power must still be availabe to push the bike through the air and other friction sources. At idle rpm back-EMF and bearing and aerodynamic friction eat up all available mechanical power, thus idle RPM can only be reached in actual vehcile operation on a downhill gradient steep enough to produce suffcient gravitational force to overcome drag and friciton at that speed, as the motor cannot contribute a single mNm to vehicle propulsion at it's idle RPM.

As for controllability, wide power-PWM is indeed needed for a solution. The beauty of such an electric direct drivetrain is that it does not need gear shifting in order to be usable from standstill to max speed, but it DOES need good power controllabilty. Having to additionally "shift gears" as Mr. Zehrbach puts it or switch from 3 to 6 phases as in your case is for me at least a backward step and can be detrimental to rider health due to carpal syndrome in the right arm when the right hand must perform the duties of the lacking controller power-PWM :-( In that case just a push button would suffice, no need for a twist throttle...

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

If you read further in that thread you will find that the motor of the "Thunder 8KW" I have has an idle of 1326RPM and the scooter a GPS verified top speed on flat ground of 97km/h, so there is really a big difference in idle and "real" RPMs.

Dear Johnny

Firstly,this is the motor's winding arrangements in unique way.6 phases designed would be more magnetic amplifier than 3 phases designed.So our 5kw scooter could be accelerated easily to 60MPH than 8kw's 97km/h,boosting our 6kw motor to 184Nm torque only needs 4108w output power.

Do you know our mechanical gearshift design(the similar as Vectrix's planetary gear)in 1.5kw and 2kw motors seven years ago? Mr.wookey has been great impressive in his Efun A 1.5kw.

I've had a very useful discussion with E-fun regarding the E-fun A, sold in the UK as the Sakura S50.I posted a summary of that discussion on the UK forum:
http://electricmotoring.forumup.co.uk/viewtopic.php?p=2053&mforum=electricmotoring#2053

Now our 3kw~6kw motor are advanced to electronical gearshift design with 6 phases winding arrangements.With good quality material and design, Efun motors can effectively maintain an idle current (no load) under 4A, and achieve max efficiency over 90%. All motors run mostly on the platform of average value 85% efficiency . This helps achieve less motor wear and longer lifetime while prolonging the range.

Amoyee Chen

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Secondly,idle rpm must be a lot higher than the expected max level speed of the bike because air resistance is over 70% in drag coefficient.

for instance my Vectrix has a peak input power of 29kw.
power needed to hold 110kmh is 13kw
power needed to hold 80kmh is 4.5kw

btw, how much extra are they charging for the 8000W model?

So faster speed is uneconomical.This needs more energy for ranges,but where to put bigger size and larger capacity battery such as 90Ah?

Amoyee Chen

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear MEroller,

Yes,we just add a push button for shift mode, not a twist throttle.

Amoyee Chen

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear MEroller,
Yes,we just add a push button for shift mode, not a twist throttle.
Amoyee Chen

Amoyee, that is clear to me. What I meant to say is that with just an on/off function of the normal twist throttle it in itself could be replaced with a push button. No need for a twist throttle if it just functions like a switch.

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Thanks MEroller,we will consider your suggestion and test it.

Amoyee Chen

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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

What we have here is either dry Asian humor or a misunderstanding of dangerously epic proportions. If we see a new model with a "Go" button instead of a throttle, we'll know to thank MERoller. ;-)

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Maybe we can design a multi cruising push button instead of twist throttle to avoiding Mr.MEroller's right arm hurt:-).Sorry,it must not be whole replacement.Wide power-PWM will be a consider either in 3 phase or 6 phase modes. We thank MEroller for his information and experience that will be a lot helps.

LeftieBiker
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

In my experience, going from a 1/4 turn throttle to a 1/2 turn throttle allows the rider to more finely modulate that steep power increase, by stretching out the increments over more travel of the Hall Effect magnet inside the throttle. It doesn't solve the problem, but it did noticeably improve the off-stop power delivery of my ZEV, as well as making it somewhat easier to hold a specific speed.

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Maybe we can design a multi cruising push button instead of twist throttle to avoiding Mr.MEroller's right arm hurt:-).Sorry,it must not be whole replacement.Wide power-PWM will be a consider either in 3 phase or 6 phase modes. We thank MEroller for his information and experience that will be a lot helps.

:-) However, I didn't buy your scooter (though it was highest on my wish-list) so my arm has healed again, and now I can ride on snow and ice too :-) Smooth power PWM rocks, go for it!

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

Dear LeftieBiker,

Before 6 phases separation in our controller,we had stretched out the increments over more travel of the Hall Effect magnet inside the throttle.The old design rang was only 1/3 available in its turning angle.
original designed range.JPGold design of Hall Effect magnet inside the throttle.JPG

New design could be extended BD to DE for getting total 1/2(BE) available range in its turning angle.See their comparative curve.
new design of Hall Effect magnet inside the throttle.JPGCurve-1.jpgCurve-2.jpg

Is the new design similar to your ZEV's?

Amoyee Chen

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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

The half-turn throttle I'm using isn't the (1/4 turn) one that comes on the ZEV. It was tested and then suggested by Chasbro in this topic:

http://visforvoltage.org/forum/11039-xm-3150-throttle-response It comes from the TNC scooter site. It isn't the same unit shown above, and I have no way of plotting its response, but I suspect it's similar in function.

wookey
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

MERoller - You generalise about the throttle/controller combo being too 'digital' (i.e on/off) in E-fun models, but have you tried any model other than the 4kW version you mention? The power/throttle response on the E-funA 1.5kW (with BLC3000A controller) seems sufficiently well-graduated to me. Clearly things have moved on since then (to controller-based electronic phase-switching rather than mechanical, which has to be agood thing), and much higher peak power, but I just thought it worth mentioning that this not an accross-the-board issue. I don't know how many controller variants there are in the newer, higher-powered models - are they effectively all the same? Amoyee? It does seem that they have recognised this is an issue and are in the process of fixing it.

Wookey
Sakura s50 (Efun A)

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

@wookey: I think the problem stems from the fact that a 500W or even a 1500W Scooter really doesn't need that much fine control, as there is not that much power available in the first place. But this simple more or less commutation-only approach of operating a brushless PM synchronous motor no longer works well with a more powerfuly 4, 5 or 6 kW Motor, as they have a lot more power that needs some finer moderation in many traffic situations. Stronger motors therefore need more sophisticated power control in order to operate them safely.
No, the only Efun Scooter I rode was that 4kW D scooter. After that I was so disghusted I had to look for more promising sources.
Why am so intense about this? Because professionally I deal with VERY smoothly power-PWM-controllable rotary solenoids. The only difference of these solenoids to a pancake-style synchronous motor is that they have a matching number of magnetic poles and stator poles and thus can only be used in a limited angle range, in our case with four poles around 70°. But they can generate a lot of torque without the help of gear reductions and are lightning quick and thus are a very robust alternative to brushed "DC"-Motors with gear reductions for the valves we produce.

So it was nothing more than natural for me to assume that an electric scooter with a FAR more powerful motor than these 60 to 100W solenoids would also employ this proven power-PWM technology (our company has been using it for over 10 years now!) for smooth throttle response and torque control, particularly from an EV-veteran like Amoyee Chen. I was proven wrong :-(

However, this thread and the discussions which have developed here are clearly helping to improve this situation in the future, which is a good thing! Only when issues that require attention are actually brought to the attention of a developer will progress become possible.

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

Xiamen Efun
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

I don't know how many controller variants there are in the newer, higher-powered models - are they effectively all the same? Amoyee?It does seem that they have recognised this is an issue and are in the process of fixing it.

Mr.MEroller is right.Your 1.5kW/48V motor needs max 40A and our 2~2.5kW/60V need only 50A even with powerful mode in power/speed gearshift,their throttle responses all seem sufficiently well-graduated. But using the same throttle,our 3kw(like XM3150)~6kW motors no longer work well especially in the first place.Now it seems there are 3 threads for solution.

1)Mr.Charles replaced his stock throttle with the TNC and Magura throttle adding resistors would be a help because of only max 65A supplying with his XM3150 controller.
2)As for more power of our 6 phases motor,we have recognised that a scooter with the start-up current less 50A really doesn't need that much fine control if it is in 3 phases mode.So electronic phaseswitch must be waken inside our controller just like mechanical gearshift in your motor.That is our improvement now.
3)About wide power-PWM design,Mr.MEroller is an expert.I have two questions for your advice (also concerned by most of customers):

a)With a smooth throttle, is it possible going quickly across a street intersection while a green light turning?It seems to need an acceleration to max speed within 7.2 seconds they hope.
109.JPG111.JPG

b)Sometimes high startup torque is necessary to get start-move-stop-start on the halfway of steeper slopes.Can a smooth throttle be able to hold and restart quickly?
the steepy hill with 20 degrees not 20%(3).jpgD2.JPGD.JPGC.JPG

These all are our works with 6-phase mode in the controller.

Amoyee Chen

MEroller
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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

3)About wide power-PWM design,Mr.MEroller is an expert.I have two questions for your advice (also concerned by most of customers):

Don't stress that "expert" bit too much in my case, but from my own experience I can at least answer the two questions :-)

a)With a smooth throttle, is it possible going quickly across a street intersection while a green light turning?It seems to need an acceleration to max speed within 7.2 seconds they hope.

First of all, the term "smooth throttle" could be ambiguous (two or more meanings): It could mean that throttle gain is not directly translated into increased power output of the controller, but rather dampened, with a certain delay. In Kelly-speak "Throttle Up/Down Rate". This is not what I mean with that term.
I mean that there simply is a more or less linear ratio between throttle position and controller power output, and that the controller "obeys" the throttle with only minimal, ideally unnoticable delay. In that case quick acceleration from standstill is more or less up to the quickness of the rider's throttle hand, and that will ideally be in the range of 100 to 200ms from zero to max throttle. But just as much it is a functionality of the controller, in that startup current / stall current is not unreasonably tuned down. With a highly stall current limited controller even the most instant throttle surge will only allow sluggish takeoff performance. With the best Wuxi throttle and the bigger Kelly KEB72801X in my 5...8kW scooter I can now easily outperform many of the less powerful cars out there when it comes to taking off from a green light, despite the fact that I can almost as easily keep a constant sub-walking pace speed with minmal throttle setting.
As for 7.2 seconds - what speed would that apply to? 0 to 50km/h? If it is meant for that speed range 7.2 seconds under full load (2 persons for example) would be quite sufficient for normal traffic situations, though quicker would be more fun :-) (but less range...)
And by the way: sitting two people on the scooter in a dynamometer test won't really make much difference to an acceleration measurement, unless the dynamometer's inertia/load setting is also increased accordingly. But I am sure you are aware of this.

b)Sometimes high startup torque is necessary to get start-move-stop-start on the halfway of steeper slopes.Can a smooth throttle be able to hold and restart quickly?

My answer is basically the same as above, this time though the other way round: high startup torque is first and foremost dependent on the motor and controller setup, especially regarding how quickly the controller steps down locked rotor current, and how strongly locked rotor current is limited in the first place.
For example: If maximum locked rotor current was initially limited to 60A, but was stepped down in -20A steps every 100ms, then a linear throttle/power ratio will inevitably lead to trouble in getting going on a steep slope, as by the time max throttle was applied (assuming the slower 200ms) only 20A max motor current would remain to get it to move. With the original Kelly KBL72201 in my scooter this was the main problem that prevented me to get going even on rather docile gradients, particularly with a warm motor. It started on only 40A but almost immediately fell down to just 20A and below.
However, with the more powerful controller I can easily start on even the 22% gradient up to my dealer's garage, and don't have to whip open the throttle very quickly either. I even have to throttle back in order not to scare myself too much :-) So, yes, linear throttle response, paired with a practical locked rotor and startup current strategy, can easily cope with starting, moving, stopping and re-starting even on steeper gradients. I would think starting with 60A locked rotor current for 0.5 to 1 second, and then beginning to tune down in -10A steps every half second should work rather well without causing harm to motor coils and magnets, but also without compromising hill startup capability. Because as soon as the controller senses rotor movement normal startup current control should commence, which again should be kept within reasonable limits.

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

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Re: E-Fun- Experiences and development of an PRC EV Vehicle ...

My experience with a "smooth throttle" is that it doesn't inhibit either rapid starts or high-torque starts. You have to turn the grip farther, but that isn't a problem. And I second the observation that putting two people on a scooter sitting on a dynomometer doesn't simulate the load of actually carry two people on the scooter. This also means that the weight of a single person sitting on a dyno-mounted scooter doesn't affect the performance measured. The person can be tiny or extremely obese, and the dyno will still only measure the power output at the rear wheel, not the effect of the weight on that output.

I forgot to add earlier that having a 'smooth throttle' can actually make it safer to cross intersections. My XM-3000, along with other similar scooters, can "stall" (stop moving) from voltage sag in the battery pack if the throttle is opened wide from a dead stop with only a partial charge in the pack. Being able to call up, say, 75% of full power from a stop under these conditions would make the scooter less likely to stall, and having a half-turn throttle is the easiest way to be able to do that.

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