DIY Electric Car Forums banner

Scott Drive 100kW AC motor & controller

174K views 441 replies 55 participants last post by  Hollie Maea 
#1 ·
efan said:
this controller+motor seem to be a new development, and I dont know of anyone who has used it..but it may be worth checking them out.

http://shop.greenstage.co.nz/product/100kw-scott-drive-ac-inverter-and-motor-package
Anybody actually seen or used this (new?) AC motor/controller combo? I see the Greenstage guys have a good history here, but this seems to be a first for them, and beats out the current HPEVS Curtis/AC50 combo by a good margin.

Thanks to efan for pointing this out!
 
#148 · (Edited)
I did.

The power is derated to 89% and the torque is derated to 76%. The power only affects the very right side of the chart where the power flat-lines and the torque drops. Shift that ever-so-slightly down if you desire. Max kw/hp only affects the very right side of the chart near the max rpm. All else would be the same.

For a really boring detailed explanation of torque and power derating see below.

1. This is a purely theoretical chart. There is no dyno data yet.
2. Some folks take the controller max voltage and multiply it by the max amperage to get the power (even if it only lasts 1 second). In this case that would be 425v x 600A = 255kw. I am using 384v which is already a 10% drop in the total power estimate.
3. If you look at the rating for this motor the manufacturer lists 55kw@190A and 320v. 190A x 320v = 60.8kw. 55/61= 90% So there is another 10% loss figured into the motor efficiency.
4. If you take 60.8kw @ 3200rpm it calcs to 181.5nm. The rated nm is only 164. So there's your 10% drop in torque.
5. If you take 164nm/190A you get .863nm/A. 600A x .863 = 518nm. But remember, we are at 384v, not 320v. 120% x .863 = 622nm. I rounded down to 600nm max which is another 4% derated just for fun.

All told, I de-rate the torque 24%. So I am figuring 76% efficiency at max amperage.

Cheers :)
 
#204 ·
Here is a chart with some info of the different motor models for comparison.

Again. Max power and torque figures are unverified and need dyno testing.

It just occurred to me that the 60kw motor is rated for 500A peak at 600V which is 300Kw, but it's listed with a peak of 240kw (4x 60kw). Which number's correct?

(240kw is just a little less than 488A(122A x4) at 500V..., but why bother to list 600V then?)
 
#150 ·
Ruckus. Im happy your working on this and i love permanent magnet ac motors but im afraid the efficiency drops as your raise the power imput the only way to know how much is to run dyno tests. Im betting the 55kw motor will be less then 50% efficient at 220kw. (just a guess based on my experiance). I also think the motors seem heavy for their rated power.... But i would love to see tests I have a dyno if anyone is interested but its for motorcycles.
 
#151 ·
...the efficiency drops as your raise the power imput the only way to know how much is to run dyno tests.
I certainly agree. That is the plan.

I also think the motors seem heavy for their rated power...
Really? An 11" series DC motor weighs 106kg and is only rated at 26kw. This is 85 kg and has more than double the rating at 55kw.

So 2X the power rating at 75% the weight. Doesn't see bad to me..
 
#154 ·
This 12kw liquid cooled motor weighs 11 lbs I plan to be using a chassis dyno soon. Unfortuanatly its a very hard to run motor and only some of the expensive controllers can run it. So Im building my own controller for it. http://endless-sphere.com/forums/viewtopic.php?f=30&t=16728

But when you have permant magnet AC motors and their liquid cooled I would expect them to be a lot more power dense then a series motor like an order of magnatude. Also check out the soup can sized motor for the BRD motorycle guys it makes 46hp rear wheel.
 
#155 ·
What must be taken into consideration is that higher horsepower can be achieved by high RPMs with the same torque and current at a higher voltage. Up to a limit, of course, which depends on the commutation frequency, and insulation resistance at higher voltage.

But when you try to get higher torque the current goes up proportionally and the resistive losses go up by the square of the current. So a 90% efficient motor at 100 amps will have 9 times the losses at 300 amps so efficiency is down around 10%. Liquid cooling will help some, but it is difficult to cool all of the motor parts, and the piping and extra components for coolant pump and radiator add weight, cost, and expense. The liquid cooling will only allow you to run the motor at higher power for a longer time before it burns up, and does not increase HP output.

I was not that much impressed by the video. You can burn out a bike tire with less than 1 HP. And the 300 amps at 100 volts is 30 kW or 40 HP into the motor. At 20% efficiency it's only about 8 HP to the wheel.
 
#156 ·
It is too bad that no one is using 400 Hertz 3-phase AC induction motors as used in aircraft as hydraulic pumps for EV conversions. There has been many forum posts of these high frequency design 3-phase motors, but they simply get buried away. I guess for the DIYselfer it is nearly impossible to source a 400 Hertz 3-phase motor, not to mention an appropriate controller. Baldor was kind enough to provide a 50 HP, 60 Hz, industrial motor for the EV community to purchase. Now if they can just build a 400 HZ version, so it will weigh about 50 LBS instead of 490 LBS...:( We the little guys though, so I do not see this happening.
 
#157 ·
The size and weight of the motor is not the major concern for EVs. It is quite possible to rewire a standard 240 VAC 6 pole 20 HP motor for 138 VAC and then overclock it to 180 Hz and 415 VAC to get 60 HP at 3500 RPM, which matches the ICE speed and torque pretty well. You should start with a high efficiency motor which will be somewhat bigger and heavier, but still it will be only about 150 lb which is less than the ICE. And you can safely get 2-3 times the torque for short durations as needed. The 400 Hz motors are specially made from very thin special steel laminations, which are very expensive, and they are also usually 10,000 RPM or more, which is not compatible with the drive train of the donor vehicle.

The battery pack is by far the largest, heaviest, and most expensive part of the build. An exotic motor is not really necessary, and the initial cost as well as compromises in ruggedness, maintenance, controller complexity, and reliability "outweigh" these amazing but often unrealistic and impractical little motors.
 
#166 · (Edited)
The Yasa motor would also be ironless, judging by its thinness and its very low weight. These motors have many advantages, but they have a few problems, one is that due to the inductance of the motor and the required external inductors, it is difficult to get power into the motor at higher speeds.

Here is the power-speed curve for the ironless Ultramotive motor: Honda Civic Conversion. Note the curved part of the power-speed curve above constant torque. The steps are because this motor has series/parallel switching of its windings. They feel they need this switching (which involves many fat cables and a lot of contactors) to overcome this problem.

Still very interesting technology. I wish they would produce them in bulk so the price can be reasonable.
 
#167 · (Edited)
It is indeed ironless - http://www.mojaladja.com/upload/elmotor/Analysis of the Yokeless and Segmented Armature machine.pdf

This shouldn't need external inductors. The YASA 750, which is a lower RPM motor has much more inductance than a Tritium WS200 Controller needs to run it. Don't have the exact numbers on the 400, but it is a very similar motor, just a smaller diameter, same pole count and a different wind I would assume to change the Kv value.

Both YASA and Tritium saw no problem using the WS200 with this motor except that power would be reduced (due to lower bus voltage and phase current). Some other issues exist with sensor and software compatibility, but this isn't too hard to get fixed.
 
#170 · (Edited)
Very interesting motor design. It is not exactly ironless, since it uses powdered iron magnetic components which have lower losses at the 300 Hz frequency. And it also uses permanent magnets. Both of these components are fairly expensive, fragile, and susceptible to damage from heat. I guess that is why the motor is liquid cooled.

It would be interesting to compare the performance of this motor to an induction motor made from thin high quality laminations, and run up to maximum speed. My guess would be that a 95% efficient standard three phase motor, carefully rewound to about 150 volts and having 6 poles, could be overclocked to 180 Hz at 450 volts and attain 3x the power at about 3x the losses, or 85%. Still very good. :)

I would expect a motor made from special laminations could be run at much higher frequencies, probably at least 400 Hz. I have done testing on a toroidal transformer which uses similar tape wound laminations as its core, and it seemed to perform well up to 16 kHz. The magnetization current actually dropped at the higher frequencies, although higher voltage would cause them to increase. I know an induction motor is not the same as a transformer, but there are similarities. :cool:

I have also wondered about the possibility of making a motor with ferrite components. That would possibly allow the use of 20 kHz or even 100 kHz, which would mean that the motor would need to have something like 200 poles, or else it would run at 1200000 RPM! Even 200 poles would be 12000 RPM at 20 kHz, but that would be workable. And of course a PWM drive would need a carrier frequency close to 1 MHz. But that is far out stuff and way off topic. :D

[edit]
You posted while I was composing my post. For as many years as I have been proposing 360 or 400 Hz motors, I'm surprised I have not coma across that website before. But it seems odd that their only vehicle motor is a big 200 HP job while 50 HP would normally be enough, especially if you can boost the torque for short durations. I don't know why you would need their special controller, although most standard controllers might not be set up to allow the appropriate motor characteristics. Some of their lower speed motors must have 24 or more poles, while the highest number I know of for a standard motor is 12. That's how many poles I used for my design of a 3-phase 8 VAC motor which I wound on a 36 slot stator from a 1/2 HP single phase fan motor. I don't know why other companies don't join the bandwagon and offer similar motors, at least maybe 180 or 240 Hz.

Actually, rereading the website, it seems that the slower motors have gearboxes. A 2 pole motor at 400 Hz is 24,000 RPM, so their 6000 RPM motor is 8 poles, and all slower speeds use gearboxes. A 12 pole version would be 4000 RPM which would be just about right for an EV.

Thanks!
 
#171 ·
Hey Ruckus,

I'm interested in the group buy. I rode in Peter Thompson's 914 this past weekend with the 40kw BLDC motor and was impressed, even with the Chinese controller which seems to have some issues.

I have a completely disassembled 914 that has been waiting for a motor/controller decision to start the conversion process. I also will be helping a friend convert a Karman Ghia so I'll probably use the same general system for both cars (probably different sized motors).

I tried to send you a PM but it's not showing up in my 'sent messages' folder so I wanted to make sure you received my inquiry.

Thanks - Jason
 
#175 · (Edited)
Hello,
Each person can choose the motor they want from the list for the group purchase. I am going with the 55kw continuous rated motor for my testing. The 600+v controller is still in development. When it becomes available I will order the 60kw high-voltage motor for testing. By then I should have a decent amount of data at 400v for comparison. They are really the same motor with a different gauge wire and number of wraps used in the winding.

I will probably test it direct drive to the rear axle to get a feeling for how that kind of setup works. A 1990 Eagle Talon will be the test vehicle.



Ultimately, though, I will be moving to AWD and full race chassis. Something like this:


or this:


If you watch some of Crodriver's vids it is clear that AWD is needed to put the torque down without undue wheel spin.

Cheers :)
 
#176 ·
i am not sure if you were inferring this method, however, you could hook motor up to the AWD transmission in the Talon and use the transmission to help you study the power delivery at different ratios e.g. in different gears....in the end you may end up wanting to keep the transmission, the only reason Tesla and the other OEMs get away with one is the ability of the motors to spin 10,000+rpm, where as most of the motors available to the DIY conversion market can only spin up to 5000rpm.
 
#180 · (Edited)
Well, before we get into a high vs. low rpm war, please everyone consider that power is power, regardless of the rpm. A low-rpm motor needs to be geared up, and a high-rpm motor needs to be geared down.

The real question is what works with the engineering already present in the vehicle? Most vehicles are designed to be happy between 2000 and 4000 rpm, so that is the optimum rpm the electric motor should be wound for as well.

The faster you spin a tranny, the more hp is lost. This is a simple fact. Not only is more hp lost at high rpm, but there is increased mechanical wear and increased likelihood of failure (not to mention the noise pollution).

Low-torque, high-rpm motors are just not well suited for conversions. If you could get 6:1 or 8:1 differential gears then they would be fine if yo wanted to put up with all that racket).

Think of it this way. In a brushless motor the only wear component is the bearings. If you take the same bearing and run it a double the rpm you will get half the life (actually much less). That is not a winning proposition.

This fact is very well quantified in hydraulic pump/motor literature where they chart bearing life against rpm. It decreases dramatically with increased rpm.
 
#181 ·
I have found that motors with higher numbers of poles tend to be larger and heavier than those of the same HP but with 2 or 4 poles. I have asked about this on a motor design forum which seems to be inactive now, and they suggested that it might be that the higher torque required a stronger frame. But I think it has to do with the efficiency of the winding pattern and with more poles there is more overlap and more space is needed for the windings. I rewound a motor with a 36 slot stator as a 12 pole three phase and that is the limit for that number of slots.

Larger motors probably have more slots so they can be more efficiently wound, and I have found that motors in the 20-50 HP range and above seem to be about the same size and weight for various pole counts and the same HP. I have three motors just about identical in size, NEMA 56 frame, and the two pole motor is 2HP, the four pole is 1.5 HP, and the eight pole is 1.0 HP. 12 pole motors are rare.

But if you can overclock the motor and maintain the V/F ratio you should be able to get higher power from the same size, and a motor with more poles can be safely pushed to a maximum of at least 3600 RPM and perhaps 4000-5000. Core loss may go up with higher frequency and efficiency may suffer, but since current remains the same, copper losses will not change. IMHO a 240/480V motor can be driven at least 2x using 480 VAC on the 240 winding without insulation breakdown or deterioration, and maybe as high as 600 VAC since that is the typical limit of the "low voltage" class of electrical devices.
 
#191 · (Edited)
Sorry folks, had to put my head down and crank for a bit (the blisters will heal). Motor ($3400) + Controller ($3500) + battery ($8-12,000) = Tough love on the bank account. :eek:

3 motors are slated for the U.S., with 2+ going to NZ. This achieves the 5+ motor price. Jack's kidding aside, each member is paying exactly their portion (depending on motor/controller model and options). Is it possible to get a motor in my hands before EVCON? Good question. Looking into air-freight options. (recommendations anyone?)

The nice thing about the Scott Drive is it already comes with many additional components which normally nickel and dime a project while creating that special look of spaghetti not uncommon to DIY. The drive includes a 40 Amp DC-DC on four 12v circuits, EVA200 contactor, controller precharge unit, external coolant temperature inputs, 9 digital switch inputs, RPM sensing, etc.. I can leave the bulk of the wiring to the gurus and focus on other things. This really helps to simplify the components needed down to a motor, controller, battery, and charger(s). I am expecting this to be pretty plug-and-play, but there is only one way to find out.

Regards,

edit: just for interest, the motors coming to the U.S. are as follows:
Scott Drive 100kw - Karmann Ghia
Scott Drive 200kw - Porsche 914
Scott Drive 200kw - my testing
 
#195 ·
Well, the IGBT's are rated for 600v continuous duty, so 425 or even 475 is quite conservative. I am thinking 136 batts at 3.65v will be 496v max, and settle to around 455v. At max amps or max range the bats will sag to about 2.8v so 136x2.8v= 380v. In summation it should be 380v-450v during use and 600A.

This calculates to 228-270kw gross. Net power should easily be 200kw. (Thus the name Scott Drive 200)

Yes, this is the "55kw" continuous rated motor weighing only 85kg (187lbs).

Motor and Controller together weigh 99kg (217lbs) and a 60-120 mile batt weighs 300-600lbs. Compare this to 600lb V8, 150lb tranny, and 100lb transfercase, and you see that the EV configuration is coming out the same weight or lighter.

Hopefully next year I will be able to test the 600-800v/ 600A version which should be in the 3-400kw range. I may order 2 (one for each axle). Watch out Tajima! (This would be called the Scott Drive 300x2)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top