# Electric Drivetrain, (900kw?)



## ChargedM90 (Feb 9, 2014)

Hi guys, I am coming here from the testosterone filled high performance automotive world.

I was throwing around some ideas, and ever since I learned how locomotive drivetrains work I have been throwing around the benefits of having an electric generator, wires, and a motor (or motors) instead of mechanical drivetrains (gearshift, clutching, shaft drives, differentials) and the problems they cause.

Now in the applications I'm interested in, the total output would need to be up to ~900kw. Are there any controllers (digital or even analog) that can handle those kind of power levels with some sort of flexibility?

Also, the ideal application would be something where the wattage generated would be dictated by engine power output automatically. So it would require minimal tuning on the controller side and owners could focus on maximizing engine output.

I googled the heck out of this topic, and I can't find anything relevant to a pure electric drivetrain, it is all info about pure electric powertrains with a battery.


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## Nathan219 (May 18, 2010)

http://www.evwest.com/catalog/produ...ucts_id=148&osCsid=b9k6mdh9mf02grqnr3mnsb08l4

here is one


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## ChargedM90 (Feb 9, 2014)

Hmm, interesting.

I think when it's all said and done, to develop what is essentially an electric transmission seems like it could be prohibitively expensive... I can only assume motors and generators designed to handle that much power would be over $5k by themselves. So add the 10k for that controller and you're looking at $20k and you still don't have an ability to control the generator...


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## Ivansgarage (Sep 3, 2011)

Have you ever though about getting rid of the electric motor, generator, controller and just using the engine that runs the generator to run the car.

What a novel idea. Just think you could be the first.


Ivan


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## Karter2 (Nov 17, 2011)

Is weight a concern ?
you may want to consider the weight of the current transmission compared to the weight of a MW generator, control system, and motors.
Also, unless you have a previously unknown source of 500kW ,low rpm motors, you will still need a transmission ( rpm reduction) and/or possibly a differential.


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## ChargedM90 (Feb 9, 2014)

Karter2 said:


> Is weight a concern ?
> you may want to consider the weight of the current transmission compared to the weight of a MW generator, control system, and motors.
> Also, unless you have a previously unknown source of 500kW ,low rpm motors, you will still need a transmission ( rpm reduction) and/or possibly a differential.


I hadn't really considered the weight, I had kind of assumed the weight wouldn't be much of a concern versus getting rid of heavy transmissions, transfer cases and axles.

Weight is definitely a concern in any racing environment, Honestly this idea is more to develop a continually variable transmission that can handle racing levels of power, with the added benefit of reducing mechanical complexity, reducing mechanical binding produced by direction changes (GREATLY increasing agility and smoothing power delivery)



Ivansgarage said:


> Have you ever though about getting rid of the electric motor, generator, controller and just using the engine that runs the generator to run the car.
> 
> What a novel idea. Just think you could be the first.
> 
> ...


Like I said, there are no mechanical ways to deliver a CVT that can handle that much horsepower, and even then the pulsing piston action of the engine and the binding of the drivetrain is a hindrance. That is what gave me the idea in the first place. Basically all the performance benefits of a hybrid supercar, while getting rid of all the heavy and unnecessary parts.

Also, I pulled that 900kw from just a Horsepower to KW conversion. But basically I just need the performance of a vehicle that weighs from 3500lbs (stock cars, sports cars) to 5500 lbs (off road racing vehicles). More for the offroad as they have larger drivetrains that weight a lot and are under much heavier abuse. But both can use engines up to 1,500hp.


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## Karter2 (Nov 17, 2011)

Well, if you are thinking Off Road, or any performance car ( except drag, maybe ?) ,..then you wont want the weight of motors in the wheels.
So you are back to inboard motor(s) with drive shafts etc.
Probably something like the Drayson drive train . http://www.draysonracingtechnologies.com/product.html?Motor-Transmission-Units-2
..but again , each motor & wheel has a single speed reduction transmission and drive shaft assy, so you are not going to eliminate many mechanical parts.
..and it certainly is not cheaper !.... or reliability tested.
and you still need to find a MW generator system !

This is probably the most advanced "Hybrid" ICE / Electric off road racer i have seen.
But its not near 900kW !
http://driveeo.com/oscar-eo/


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## ChargedM90 (Feb 9, 2014)

Karter2 said:


> Well, if you are thinking Off Road, or any performance car ( except drag, maybe ?) ,..then you wont want the weight of motors in the wheels.
> So you are back to inboard motor(s) with drive shafts etc.
> Probably something like the Drayson drive train . http://www.draysonracingtechnologies.com/product.html?Motor-Transmission-Units-2
> ..but again , each motor & wheel has a single speed reduction transmission and drive shaft assy, so you are not going to eliminate many mechanical parts.
> ...


Well I'll be damned, seems that is probably what I'd be looking for for motors.

Seems like there's some product out there that could deliver, and I think a MW generator could be made compact enough in theory with some more advanced techniques, but all this probably isn't feasible for anyone with a budget of less than $100k.

Thanks for the input guys


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## rochesterricer (Jan 5, 2011)

You could copy John's drivetrain:

http://www.diyelectriccar.com/forums/showthread.php/assault-n-battery-build-thread-74539.html

He is currently in the low 9's in the quarter mile and should break into the 8's by mid-summer.


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## Karter2 (Nov 17, 2011)

rochesterricer said:


> You could copy John's drivetrain:
> 
> http://www.diyelectriccar.com/forums/showthread.php/assault-n-battery-build-thread-74539.html
> .












Whilst John's is a very impressive (and effective) drive train ,..
..it doesnt exactly meet the OP's requirement of...


> ...the benefits of having an electric generator, wires, and a motor (or motors) instead of mechanical drivetrains (gearshift, clutching, shaft drives, differentials) and the problems they cause.


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## rochesterricer (Jan 5, 2011)

Then he will want to copy something like White Zombie:

http://www.plasmaboyracing.com/whitezombie.php


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## Karter2 (Nov 17, 2011)

rochesterricer said:


> Then he will want to copy something like White Zombie:
> 
> http://www.plasmaboyracing.com/whitezombie.php


That would certainly eliminate the gearbox...
...but it still leaves the drive shaft, differential, axle shafts etc.
Direct motor drive to each wheel would be the ultimate, to eliminate all the shafts, couplings, and differential ass'y.
....But it doesnt exist ...yet.


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## rochesterricer (Jan 5, 2011)

Karter2 said:


> That would certainly eliminate the gearbox...
> ...but it still leaves the drive shaft, differential, axle shafts etc.
> Direct motor drive to each wheel would be the ultimate, to eliminate all the shafts, couplings, and differential ass'y.
> ....But it doesnt exist ...yet.


So he basically wants in-wheel motors with 900kw? Yeah, not gonna happen anytime soon.


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## ChargedM90 (Feb 9, 2014)

rochesterricer said:


> So he basically wants in-wheel motors with 900kw? Yeah, not gonna happen anytime soon.


Well more like 250kw motors in each wheel. But even then this is a pretty expensive drivetrain concept.

But I'm sure at those power levels inboard mounting will be required, which still minimizes the drivetrain and having one motor driving each side eliminates binding. It still eliminates a bunch of the driveline and many of the most vulnerable parts.

Maybe some rich guy who is into off-road racing will take this concept to the next level, but all the PC corporate types today tend to focus on the hybrid movement.


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## rochesterricer (Jan 5, 2011)

You would still likely have some sort of reduction gear assembly attached to the motor. At that point it is actually more complicated than the single motor and transaxle setups employed by most factory EVs.


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## toddshotrods (Feb 10, 2009)

I don't really understand the fascination with eliminating all gears. A, sealed, single reduction unit, uses very little fluid; doesn't leak it into the environment (if engineered and maintained properly), and adds a lot of flexibility to the motor's design and use. Eliminating it adds a ton of complications, and likely a compromised motor design, to save a tiny bit of complexity and an insignificant amount of (recyclable) fluid.

Consider how much that single reduction has allowed Tesla, Rimac, White Zombie, Rocket, etc, etc, to accomplish...

Additionally, it allows a point to fine-tune a single motor design to different uses. My motorcycle uses a single (chain & sprocket) reduction, which allows me to adapt different motors and tailor the gearing for urban riding and/or 200+mph speed feats.


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## Karter2 (Nov 17, 2011)

Something like this ..on a larger scale..
( from another thread)
http://vimeo.com/68397135

Or how does this sound from an off road vehicle site..


> But instead of spinning a mechanical driveshaft and differential, this engine pushes its 1,570 horsepower into a General Electric GE150AC drive system that fires 1,171 kilowatts of electric juice into a pair of motorized wheels.


 ..but possibly not exactly what you had in mind tho' ...
http://evworld.com/article.cfm?storyid=249


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## McRat (Jul 10, 2012)

Get 4 wrecked GM Volts. $28k. Over 900kW when using ELR calibration.

Run 8 tires, with linked steering. Batteries will weigh 900lb air-cooled, 1700 watercooled.

Tube frame, glass body, about 4000/5000 lb.

High 8 second ET's and a 200 mile range.


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## Karter2 (Nov 17, 2011)

McRat said:


> Get 4 wrecked GM Volts. $28k. ....
> .... and a 200 mile range.


 Not exactly simplifying the drive train is it ?
and how do you figure a 200mile range ??


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## toddshotrods (Feb 10, 2009)

McRat said:


> ...about 4000/5000 lb...
> 
> ...High 8 second ET's...


That's the one that gets me - 2000lb, single-focus, drag cars haven't been able to cross into 8-second territory (tough Metric is close) with the same amount of power, or more...

Unless you're talking 8-second 1/8-mile ETs?


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## Karter2 (Nov 17, 2011)

toddshotrods said:


> I don't really understand the fascination with eliminating all gears..


 Well, i suspect a transmission designed to handle 1500bhp, 1000+Nm Torque, will be a sizable, heavy, and expensive , unit.
Also even a simple reduction transmission will consume (5-8%..pick a number) of power/efficiency. At these power levels, that is a significant loss , and significant amount of heat to deal with (extra cooling system needed)
Then there are the maintenance and reliability concerns..
So..i suspect we would all rather not have a large, heavy, expensive, power wasting,.... .extra piece of kit to deal with ..
...If it can be avoided !
..But i agree, there doesnt seem to be a viable option currently available !


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## ChargedM90 (Feb 9, 2014)

McRat said:


> Get 4 wrecked GM Volts. $28k. Over 900kW when using ELR calibration.
> 
> Run 8 tires, with linked steering. Batteries will weigh 900lb air-cooled, 1700 watercooled.
> 
> ...


Holy crap, I know you from Duramax forums. Never thought I'd see you here. 

Lol, That sounds crazy enough that it might just work!

Also, my whole concept included the use of gear reduction units, probably should've clarified that!

The problem I have with mechanical drivetrains is more the binding, and the torsioning problem many of them have. I watch many offroad guys who have problems with wasting power and losing stability in drivetrain binding forces.


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## toddshotrods (Feb 10, 2009)

toddshotrods said:


> ...eliminating *all* gears...





Karter2 said:


> Well...a transmission designed to handle 1500bhp, 1000+Nm Torque, will be a sizable, heavy, and expensive , unit....


Not necessarily. One gear reduction, can be rather small, lightweight, and less costly - relatively speaking.






Karter2 said:


> ...even a simple reduction transmission will consume (5-8%..pick a number) of power/efficiency....


I have no data to back my assumptions, but I find that hard to believe when multi-ratio transmissions can be in the 10% range. We generally subtract 10-20% for entire drivetrain losses; with multiple ratios and differentials. I could be wrong...





Karter2 said:


> ...there are the maintenance and reliability concerns...
> 
> So..i suspect we would all rather not have a large, heavy, expensive, power wasting,.... .extra piece of kit to deal with...


Chosen properly, differential gears, the final ratio, rarely go bad and the maintenance is limited.



It just sounds like spending millions to save pennies - looking for a nail to hit with the hammer (engineering prowess) one happens to have.


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## Karter2 (Nov 17, 2011)

McRat said:


> Get 4 wrecked GM Volts. $28k. Over 900kW when using ELR calibration.
> 
> Run 8 tires, with linked steering. Batteries will weigh 900lb air-cooled, 1700 watercooled.
> 
> ...


Oh wait a mo ! ...its already been done ..










> The *Eliica* (or the *E*lectric *Li*thium-*I*on *Ca*r) is a battery electric vehicle prototype or concept car first shown in 2004 and designed by a team at Keio University in Tokyo, led by Professor Hiroshi Shimizu. The 5.1 m (17 ft) car runs on a lithium-ion battery and can accelerate from 0–100 km/h (62 mph) in four seconds (faster than the Porsche 911 Turbo at the time).[1] In 2004, the Eliica reached a speed of 370 km/h (230 mph) on Italy's Nardò High Speed Track. The team's goal is to exceed 400 km/h (250 mph), breaking the record set by today's street-legal gasoline-powered vehicles....
> ...The Eliica weighs 2,400 kg (5,300 lb) and seats the driver and three passengers. The body was tested in a wind tunnel. The front doors open forward and the rear doors open upward like wings. The car's platform contains 4 tracks of 80 batteries, which make up one third of the vehicle's cost. They currently require about 10 hours of recharging at 100 volts from empty to full charge, and can be easily charged off a residential power grid.
> The car has eight wheels to improve traction, and they are smaller than normal passenger vehicles, so it can be lower to the ground for better aerodynamics and stability. Each of the wheels has a 60 kW (80 hp) electric motor, giving a 480 kW (640 hp) eight wheel drive


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## McRat (Jul 10, 2012)

Karter2 said:


> Not exactly simplifying the drive train is it ?
> and how do you figure a 200mile range ??


One Volt battery will push a 4000lb car 50 miles.
4 Volt batteries will push a 4000lb car way more than 200.

Factory software limits the 16 kWh battery to 10 kWh.

A Volt weighs 3750 without a driver.


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## McRat (Jul 10, 2012)

Believe it or not...

Not only is this possible, it would be reliable as the Volt if setup correctly. The components are over-engineered to survive 100,000mi.

Why so cheap? Salvage title cars. Not much of a market for salvage title EV's yet. You are buying the batteries, controllers, and motors for a small fraction of what aftermarket costs are.

The problem? Getting the components to work in unison.


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## Duncan (Dec 8, 2008)

Karter2 said:


> Well, i suspect a transmission designed to handle 1500bhp, 1000+Nm Torque, will be a sizable, heavy, and expensive , unit.
> Also even a simple reduction transmission will consume (5-8%..pick a number) of power/efficiency. At these power levels, that is a significant loss , and significant amount of heat to deal with (extra cooling system needed)
> Then there are the maintenance and reliability concerns..
> So..i suspect we would all rather not have a large, heavy, expensive, power wasting,.... .extra piece of kit to deal with ..
> ...


Hi Karter
mechanical gearboxes do not rob anything like those numbers - most if not all manual gearboxes do not have and do not need any cooling at all
I would suspect a single reduction to be about the 1% level


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## Karter2 (Nov 17, 2011)

Duncan,
im not saying a cooling system would be needed,... but we are talking of a 1500bhp transmission in a performance situation.
Even a 1% loss in a gear box ( its certainly more) at that power level suggests 11kW of heat to be dissipated !
Coolers for differentials and transmissions are not uncommon in competition vehicles.

But the point is that there are good reasons and significant advantages to be gained by eliminating even single stage reduction transmissions if possible.


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## Tomdb (Jan 28, 2013)

Elimination of the gear reductions would mean that the rpm of the motors would have to drop significantly.

Slow turning electric motors are usually of a very large diameter and heavy.
Having available options turn slow would cause them to run in an inefficient part of tier performance range.

One gear reduction can solve alot, even at a loss of 1-2%. This loss will be compensated by the gain in efficiency of the motor inverter being allowed to run at higher speeds/frequencies.

From my experience in the field of drivetrain specification and sourcing (my daytime job), i have seen motors that make your jaw drop. 

For a sports car project, unfortunately which is now in the freezer, we went looking for an high performance dual motor setup.

We ended up with the following setup:
2x ac inductions motors
Specs:
100 kg total driveline (motor plus reduction)
320 Kw peak
30.000 rpm redline

efficiency of 93% average battery to wheel during normal driving.


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## Karter2 (Nov 17, 2011)

Tomdb said:


> Elimination of the gear reductions would mean that the rpm of the motors would have to drop significantly.
> 
> Slow turning electric motors are usually of a very large diameter and heavy..


Exactly,..low rpm is part of the challenge for "wheel motor" designers.
However, size and weight do not seem to be a problem, with commercial designs ( Protean)of 420mm dia giving 80+kW, 1000Nm, @1000rpm, and weighing only 31kg including the inverter drive and controls.
And naturally the usual claims of high efficiency !

As a drive train specialist, i am sure you would also welcome the possibility of eliminating as much unnecessary moving parts and weight , as possible.
This is already a reality in low weight EVs (scooters etc), and heavy commercial vehicles ( bus's), so is just a matter of time and development for it to reach the mass consumer vehicles.
..Maybe soon ?


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## Tomdb (Jan 28, 2013)

Thing is i would go for the delft approach. 









A "normal" motor and then a single stage reduction. Because this is existing and proven technology. And in a performance vehicle designing new hub motors will be a giant undertaking. 

But without drifting offcourse of the opening post; 
Do you have a budget? i would suggest going the rimac way. Inboard motors based on existing core (stator rotor) with a single end reduction for the most effective in terms of cost and time.


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