Despite my last post regarding the miniscule number of actual electric cars on the road, and admonition that we are firmly at the BEGINNING of the tinkerer/innovator market stage, the wider press frenzy and flurry of OEM press releases has had an effect of urgency. Although remaining largely unobtanium, the blizzard has certainly spurred the aspirations of the more inventive among us. And it solidifies my feeling that there is a lot of electric car to be yet built. Basically, we don’t know what the future vehicle looks like.
This is a bit startling when you think about it. Not only do we have new batteries finally, but innovation in this area continues predictably enough. But on things like the Electric Motor, what can really be done that hasn’t been done in the past 150 years?
Actually, a lot. Several viewers have pointed me to some startling innovations, largely coming out of the United Kingdom.
Electric drive trains share the basic problem ICE drivetrains for automobiles exhibit. A typical 15 inch wheel and tire rotates about 750 rpm at 70 mph and correspondingly less at lower speeds of course. Electric motors do not operate well at 750 rpm and are really unwell at 50 rpm. We say they develop full torque at 0 rpm, but that is a little misleading. What they mostly develop is heat at those levels.
The “sweet spot” of course is much wider at perhaps 2000-3500 rpm for most motors of AC or DC. And so in direct drive applications, you will often see a gear ratio of 8.25:1 in a single speed gearbox.
Converting existing cars, the single speed 8.25:1 gearbox is largely unavailable. So it is usually easier to just retain the existing manual transmission.
A couple of problems there, none insurmountable. First, many desirable vehicles don’t have a manual transmission. Would you believe the most popular vehicle of ANY make is still the Ford F150 pickup truck? ANd would you believe they just don’t make them with manual transmissions any longer? Unobtainium.
There is weight and efficiency loss through the transmission, and one of the most popular questions we receive at EVTV is the continuous suggestion that we bail on the transmission and go direct drive.
Direct drive poses some all around problems, but by far the largest is this matter of RPM matching.
Basically, this would involve a drive train somewhat like the Tesla Model S with a motor IN an axle with gear reduction linearly between the motor and the wheel. All doable. All expensive. All custom.
There is actually an alternative – magnetic gearing.
Magnetic gearing does an rpm reduction and a torque multiplication based on magnetic coupling using rare earth permanent magnets. Magnegear is a good example. They do a rotary magnetic gear reduction for the oil and gas industry drilling operations.
These are frictionless, very low maintenance and very volumetrically attractive notions. But aren’t electric motors mostly about magnets and magnetic fields. Yes, Johnny, they are.
The video above describes a company with a technology for magnetic gear reduction, but their Pseudo Direct Drive takes this a step further – putting the gear reduction IN the motor. By combining magnetic field windings with a series of rare earth magnet rotors, they do both the motor thing and the gear reduction in one package.
In this way, you can have a motor spinning at 2500 rpm and the shaft of the motor spinning at 500 rpm in a very small package.
Yasa Motors carries this a step further. Robert Lewellyn does a take on this I found engaging.
They are cloyingly careful not to include any details in their description, but it appears to use a three phase Sevcon controller to spin an outer rotor of a few neodymium magnets that then induce current in a series of wound armature coils – effectively doing the gear reduction with an output of 750 NM of torque in an incredibly small package. Better it appears you can STACK these pancakes to get whatever power level you want.
Forget wheel motors. By putting these inboard with a short shaft, you can get all the advantages without the unsprung weight and durability issues.
So electric motors for electric vehicles really do have some peculiar needs and requirements. And there is indeed room for innovation in such a mature technology as electric motors. I find both of these technologies utterly fascinating. But they share a common theme – a 3 phase space vector inverter.
We don’t really have one.
I have gone on about bottom balancing since late 2009 in a world of top balancing BMS gurus who insist I’m a whacko. Now WHAT OEM has MORE experience with Lithium Cells than ANY other?
The answer will NOT surprise you. DeWalt. They’ve been using these cells in power tools for years now. And as it turns out, their BOTTOM BALANCING PATENT rather predates anything I might have ever said about this.
I also said that Akio Toyoda, Chairman of Toyota Motors might have FELT the Winds of the Future but he could not BE the Winds of the Future. Apparently he does not agree. The company announced at their Las Vegas Dealer meeting that there would be 35 Tesla/Toyota RAV-4s built in 2011 with a product introduction in 2012.
Purported to equal performance of the gasoline version, the vehicle should have a 100 mile range and drive much like the ICE version.
The company also announced the 2012 launch of the Scion IQ EV – a 65 mile per charge city roadster about the size of the ill fated Daimler Smart ForTWo. Again, no pricing or planned production numbers.
They do also plan a plug-in version of the Prius with an electric range of 14 miles. So Toyota seems to have gotten electric religion, at least at the press release level. Next year in Jerusalem. Always next year…
I must say I find both these pure electrics from Toyota attractive.
Jack Rickard
As wonderfull as these inovations are and as large an impact that they could have on the conversion industry , one thing is missing. Availability. Can I , for money , have one tomorrow? The answer is usually always a resounding no. OEM only , patent pending , testing and development phase blah blah. What I love about the Chinese lithium suppliers is phone call + chinglish + credit card = cells. No BS.
Damien Maguire
Agreed with Damien.
We should learn from those Chinese, and perhaps from others to do the same with EV conversions…
Just do it!!!
I would say: “Build 1 EV at a time, innovate through uniqueness!”
My 2c…
-Y.
OK, I took delivery of my Leaf last week (a week ahead of schedule) and am delighted. It’s in every way a real car: nice quality, great A/C, very smooth, lots of bells and whistles, seats five in comfort with luggage space. I don’t come close to using all the available range and it just seems effortless.
I’ll admit that I’m a heat seeker on these things – I had one of the first rotary RX2’s and a couple of ZENNs. The dealer says he can sell every one he can get. I’ve given lots of rides to friends and the reaction is predictable – they want one. You can’t justify it financially – you can buy a lot of gas for the premium on the car price – but it just feels good.
So Jack, I agree that we are at the very beginning of the curve, but if the product to follow improves on this one, we will have some exciting times ahead.
Now to get the rear battery pack on the e-Bugeye finished up ….
Fred
I have been wondering about how well a CVT transmission would work with electric drive.
http://en.wikipedia.org/wiki/Continuously_variable_transmission
I was hoping to find a old DAF 750 to experiment with but these were sold in the UK and I never found any here in the US.
Here’s a image of the drive system in the DAF 750.
http://www.forix.com/8w/altpower/daf33-transmission.jpg
Had the idea I might be able to get one to work in my Opel GT. Something about shifting gears in a electric car feels wrong to me.
To anyone here that likes videos with in-depth info on all things EV ;), check out some of the other ‘fully charged’ videos via the YouTube link below the YASA motors one.. The previous episode (no#22) features the CEO of Nissan/Renault in an interesting 20 minute interview.
I’ll be back for your 2 hour session next week Jack! And thanks for giving me something to watch in the meantime..
mcrickman, There’s a fair few small cars sold in the UK who’s auto box is the CVT type. The belt is a kind of steel chain that also works on the compression side stiffening up into a straight piece believe it or not.
Nissan, Chevy Volt, Mini, Audi, Honda, Toyota, Volkwagon….. Try Google Images with “car cvt”.
The trick might be to make it suit the motor.
===========================
Good pair of Blog write-up’s JR. I’m indebted.
One small thing. I could of sworn on my cats grave there was such a thing as an Automatic magnetic clutch and gearbox they once used on diesel electric trains. Mag. clutch, yes but also an auto box?
This comment has been removed by the author.
@mcrickman
I’m not sure I’d want to apply that much torque to a belt driven CVT. Sounds like a catastrophic failure waiting to happen.
Personally I’ve been considering employing a hydrostatic drive setup, like Hydraulic Innovations has done with their motorcycle.
I too have been running transmission options through my head. Unfortunately building a better battery is a little beyond my abilities, so too is designing a better electric motor. But tinkering with existing ICE transmissions to make them better suited to electric drive seems within reasonable ability.
Like Jack i dont like things in my car that seem strange (some after market engine immobilizers drive me crazy) and having a clutch pedel in an electric drive car seems strange to me. If you watch through the “Fully Charged” series mentioned above, Robert Lewellyn get a ride in a converted range rover in which the driver trys to explain loud clunking noises in the transmission as always been there, but just masked by engine noise. I dont buy it. Again i think that is a working solution but not the best we can come up with as a community of “tinkerers and Innovators”
I have not yet looked at the CVT option yet but im looking into it. My favorite idea right now (and will probably change by weeks end) is using an automatic planetary system with 3 gears and no torque converter and changed manually. A sequential shift style system would feel very drivable and not to strange. A paddle shift system on the steering wheel i think would feel very natural. I know this doesn’t leave room for Jacks beloved squishy bits (clutches and such) but from a user interface it might seem simpler. I like to think of it giving the keys to my grandma and imagining how easily she could adapt to the vehicle.
If anyone has any references to this style of set up working (or not working) please share with us all. As well as all opinions both for and against.
Cheers!
There were a number of CVT cars produced here, too, including many hybrids. The problem with them is their generally electronically controlled, so there’s a big problem hacking the Powertrain Control Module to operate the transmission, especially without its bespoke engine.
More practically, the Subaru Justy from 1987-1994 offered a CVT that was a “push belt” design powered in compression as Andyj points out. Here’s a good overivew of it:
http://www.dustysjustys.com/ecvt.htm
Problem there is the unit is just not strong or durable enough for EV use, being designed for a sub-2000lb car with a 1 liter 70hp engine. Its going to have trouble with the low rpm torque an electric motor can dish out, particularly if the car also gains weight.
The DAF unit is much more robust, and probably also more numerous, even today. It was in production through the late 1960s, and Variomatics and parts are out there, primarily in Northern Europe, but it will take something of a devoted effort to use this powertrain. Always been a favorite of mine, the twin belt Variomatic. It has never gone away, either, just been continuously refined and adapted by Van Doorne Transmissie, and still the transmission in some CVT versions of cars in production today. In theory, a CVT is the ideal ICE transmission.
Remember, snowmobiles and scooters also use CVTs, so depending on the size of your vehicle and your talent, a light 2WD or 4WD car using a motor and snowmobile transmission with a propshaft to every driven wheel might be just the ticket. Its a little too science fair/barnyard engineered for my taste, but it could be a light and elegant system, particularly with agni or pancake motors.
The really nice thing about the CVT is the motor always spins at its ideal RPM. That takes care of motor fan cooling, burning brushes when stalled, and high-amp low-rpm wear & damage. That’s also why you see it on hybrids- its an effective way to positively control the speed and load profile of the accessory electric boost motor.
On the road, a CVT also takes a little getting used to, especially with an ICE. Nissan or Toyota actually had to program some of the benefit of fixed motor RPM out of one of their CVT cars because the customers complained about the “racing motor” that never shifted and vibrations at lower speeds. Silly, really, but that’s what the customer wants.
Still, for an EV a CVT is an interim step primarily useful for making a forklift-based motor into a road EV motor. Lots of parts, mechanical losses, weight and packaging issues, but it does more or less solve the problem. True road EV motors are coming, though, so I wouldn’t build a whole car I wanted to keep forever around a CVT.
Just a thought…
Ben-Canada:
There is a transmission precisely as you suggest- the Lenco. It is made of two range planetary gearsets, in a huge variety of ratios, and you just stack up the gearset housings to make as many gears as you want. Most EVs would do with 2 well spaced ratios. Very, very few would need more than 3. Also can be had with a nifty fixed reduction box up to 56%, and can be used to make the transmission an OD by installing that gearset “backwards” for overdrive instead of reduction.
Very expensive. Something like $6500 for a two-speed with the OD/reduction box and reverse CS3 unit, not including machining for the input/coupler and motor mount interface plate. They apparently don’t particularly want the EV business, either, having brushed Jack’s inquiry off to a “supplier partner” who wanted $12k to get started on a transmission. Whatever.
Its a slick piece of hardware. Strong, light, direct drive. Can’t spin it backwards, though, so no electric reversing with an AC motor. You use the reverse gear. You shift with either a rod/linkage setup of one rod for every gear, or a CO2 air shifter. The Lenco is bulletproof, completely configurable in ratio and the CS-3 is relatively light.
I’ve been looking on ebay and RacingJunk.com for 2 years for a CS-3. Not a single one has come up at any price. A factory freshened CS-1 sells for 85%-90% of a new one, even if its 25 years old. A Lenco transmission is apparently a keeper…
http://www.lencoracing.com/
TomA
Hey, good write-ups folks. At this rate JR can just sit back and sup the whiskey.
Scooter CVT’s usually have the belt grabbed on the engine side when the rev’s spin out the weights. There is also a speed related clutch on the driven side. Kinda ends the instant get up and go of an electric motor.
For Agni? Here’s a CVT Diesel motorbike:
http://www.dieselmotorfiets.nl/
Note the compact box at the rear of the motor.
I’ve always liked the idea of a hydraulic clutch/box. Throttle and load can be directly related to RPM with the right kit. It’s do-able, even on motorbikes!
http://en.wikipedia.org/wiki/Honda_DN-01
DN-01’s fully variable transmission box:
http://www.topspeed.com/motorcycles/motorcycle-reviews/honda/2008-honda-dn-01-ar47277/picture213295.html
So long as we’re off in the weeds here, don’t forget the NuVinci, maybe the most promising CVT. It uses spheres to change the ratios, not belts.
Very interesting, and in production by a few bicycle manufacturers under license.
http://www.fallbrooktech.com/home.asp
Unfortunately, the NuVinci is still pretty much an idea. Slick website with breezy, high concept sales talk about all the great applications from agricultural to windmills and supercharger drives, but no products. This is the classic “license my intellectual property to OEMs without building anything” American innovator play. They are busy appointing auto industry types to their board and raising money. Lots of press releases, Memoranda of Understanding with major industry players, Chinese government agencies and the like.
Still unobtainium. Worse, its mostly nevermadium.
Great idea, though.
Over & out.
TomA
NuVinci system has actually been used in several production bicycles, but they all disappeared and changed into regular bicycle gears after one year or so.. Maybe the cyclists just didn’t get the idea or maybe the efficiency wasn’t that great. You don’t want to waste energy, if it comes from your very own weak muscles.
The efficiency is probably very high, but on a bicycle you’re dealing with the most efficient machine ever designed, so small losses are magnified.
My WAG is the durometer, strength and durability of the balls and friction surfaces that transfer power are the problem. This is also the problem with scaling the unit up. There isn’t one word from Fallbrook Technologies about the materials science breakthrough their development curve needs in order to crack this design. Its like the rotor seals in Wankel engines, or the bearings in turbochargers. Getting the wear parts right in the field is the hard thing, not proving the patent or signing on partners. In this case, the “development partners” are supposed to figure all that out under license. Right.
Just what it looks like to me…
Yasa is technically available for 10k£ including a 100kW sevcon controller for it. and you need two sets..
the magnomatics thing is vaporware. will likely never be. it seems to me that while magnetic gearing can work, its strength at the final stage is the decisive one so you can’t think of it like a motor on a normal gearing. it is simply better to just have a stronger final magnetic stage thus a straight forward PM motor. and that’s also what the Yasa one is. it has no magnetic gearing.
I have come to believe in socalled direct drive directly on a differential. white zombie mananged 0-60mph in 1.8seconds directly on a 1:3.5 diff. and you can get diffs up to 1:5.71.
simple a nine directly on a 4.88 diff is probably a very good solution for typical conversion. although the controller will need some significant current capability for the first second from standstill.
but it’s super elegant to do with gearbox, clutch and the difficulty in making an adapter plate. plus the weight and the space you save.
I dunno, Dan.
Sure, with a transwarp motor already fitted with a standard yoke, its just a matter of buying a custom length driveshaft and you’re done, but is it really a good package on the road?
Drag strip performance aside, with 215R60/15 tires and a 4.88 R&P, the motor turns 4000RPM at just 61mph. I wonder how much torque is left at that point, and to do 75mph takes you right near 5000RPM. Even if you had the voltage to spin that, you’d probably have trouble developing enough torque to push the car through the air that fast.
My bigger concern is actually at the other end of the equation, though. A powertrain like that is going to have a hard time, even with external cooling, in really low speed work like the stop and go traffic we often see here in the Northeast and many other places. I don’t think 4.88 gearing is deep enough to protect the brushes and comm bars in a commuter crawl or some other low speed situations.
The way you drive such a car in real world traffic has to be different than what people would expect would be OK. The operator would have to be sternly warned not to use the go pedal to creep along uphill, but rather to hold the car with the brake, and use the throttle to actually move, because even against a light load and with forced air cooling, continuous moderate amps into a nearly stationary armature would likely push a series DC motor to the limit. Who would be thinking that creeping up an off-ramp at 2mph in a rush hour commute could blow the motor? Its enough to put an Amps/speed x time warning buzzer on the dash…
Single-speed may be a good setup for a no-compromises drag or street/strip car (especially where you are switching the pack back and forth from all-series to parallel banks, or switching the motor from 4-turn to 2-turn like the Enertrac prototype is doing) but on the road in a regular service passenger vehicle, it seems multiple gears are worth the trouble. The clutch is a little more debatable, but I don’t like 2 second gear changes that just eat up the synchros, so it isn’t all gravy to give that up, either. A clutch also makes a handy sacrificial shear pin protecting the more expensive hard parts in the driveline. Jack calls his a “fuse…”
That’s the nice thing about an AC motor, higher revs. I could live with my car as a single speed 7:1 (2nd gear overall) ratio, which is what I do most of the time anyway up to around 65mph, and that’s with the voltage limited Curtis 1238 set at 6500 rpm max, it can go to 8K. Not sure my transmission would be happy at 8K for long though.
What about monitoring the motor rpm and the transmission rpm and executing a shift only when the parts intending to mesh are a the same speed. The operator or an automated system indicates a desired shift, the motor unloads the transmission, shifts into neutral, and then the motor does what’s needed to synchronize the gears intended to mesh, engages them and reapplies power. With regenerative braking, an electric motor can do things an ICE can’t, something that can be taken advantage of.
Klaus, unless regen pumps into supercaps (too expensive) the gains are not there. 🙁
Tom Alvary, care to have a look?
http://www.industrial-gear-repairs.co.uk/kopp.htm
https://docs.google.com/viewer?url=http://www.net-eng.co.uk/pdfs/Kopp/variator_dimensions_list.pdf&pli=1
The downside is the weight. 388 lbs for 100 hp. 🙁
OK, I had a look.
These appear to be hydrostatic variable speed drives for running conveyor belts and such. Low speed- under 2000rpm, most about 1500. Very heavy. Fluid drives, so efficiency is between 20% and 85% at best. I just don’t see the application to a vehicle, let alone a road EV, unless its a JLG cherry picker, a movable stage or something similarly heavy that needs to move very slowly and gently.
Here’s the full Carter Variator Catalog:
http://www.renold.com/nmsruntime/saveasdialog.asp?lID=899&sID=894
Andyj, right you are. I was considering it’s use to quickly slow down the motor when accelerating and shifting to a higher gear and thereby significantly reducing the wear & tear on the synchros when no clutch & flywheel is used. (The motor would accelerate when downshifting for the same reason.)
“Andyj said…
Klaus, unless regen pumps into supercaps (too expensive) the gains are not there. :(“
I’m seeing a 3-4% gain from regen compared to the Ah delivered by my battery pack and this agrees with the number of Ah it takes to recharge my battery pack after a drive, too. If your system has regen then use it any time you would have used your brakes and you will see a benefit without ultracaps.
If you are choosing between two drive systems, one with regen and one without, and extending range is your _only_ reason to choose the regen system then it may not be worth it to you.
Klaus,
I was thinking the same way. I’d also intended to use a hat switch on top of the gear stick to pre-select the target gear, while in neutral.
Regen has many uses. Gizmo’s 3~4%.
Klaus’s & markrmarkr’s fire button on gearstick to drop motor revs for gearchanging.
Regen for me to stop uncontrolled speeding whilst going downhill.
Now a tale to tell. My old car at 87k miles (130Km) wore through a front pad on a disc brake. A quick drive side fix was spray the side of the disc with chain lube. Now as you can see I’m a fairly economical driver. But this really opened my eyes to using the brakes. My fuel mileage went up from ~390 miles to a tank to 450 miles. A 15% saving. I’m afraid that is why I’m a little down on regen for cell recharging but have nothing against it at all. They say they can find 40~60% gains with supercaps used in town driving.
I’m unaware of anyone who has demonstrated 40-60% gains with Supercaps. I BELIEVE I’ve read everything every published on the topic anywhere.
Supercap programs generally start with impossible goals, and degenerate in the end to with more advanced switching circuitry and better predictive software they BELIEVE they might achieve what they started out hoping for, in order to end the paper on a high note after really achieving almost nothing.
Kind of like the wheel motors.
I’m in the camp of using regenerative braking to produce power brakes without the vacuum pump. We did extensive testing of this to my satisfaction anyway. The believe system here stems from the fact that for 100Ah taken from the pack, REGEN will replace 15 AH and so it must offer an efficiency gain of 15%.
I think this is a terribly flawed view of it as it ignores free roll and lost free roll opportunities caused by the regen itself. We prefer to compare two identical drives in the same car, one with regen enabled and one not.
If, like MR. Noto, you believe the throttle is a two position device, OFF/ON, then indeed you CAN achieve 15% gains or very nearly anyway.
If you drive moderately, the gains are more like 4-5%. If you LIKE the feeling of free roll as I do, you will find yourself in negative numbers with regen.
The problem with regen is the ac drive trains that make it possible are three times the expense of a series DC drivetrain, and this makes no sense for real efficiency gains of 3-5% or even beyond.
Jack Rickard
You got it, markrmarkr. I can see it as an option built into motor controllers down the road.
That’s the biggest benefit of regenerative braking; reducing brake wear. Eliminating them altogether would would be nice but not when in a panic stop situation. As a long time distance bicyclist, I love free rolling. It’s impact on fuel millage was confirmed when we got a car with a manual box and real-time mpg display. Low r’s, on an ICE car, and free rolling boost mileage. Free rolling to the next light or turn, without using the brakes, is fun, saves energy and gets you in tune with the dynamics of your vehicle.
JR said: “I think this is a terribly flawed view of it as it ignores free roll and lost free roll opportunities caused by the regen itself.”
Jack I don’t understand why you say this. I know you have (or had) the mini set-up so that when not accelerating you turn on regen, but nothing is forcing you to set it up that way. You could easily disable this and just have brake based regen. Ideally using the pressure transducer when you can get it working.
That way when you take your foot off the accelerator you can roll to your hearts content, and when you eventually do need to brake it all goes back into the batteries.
Am I missing something?
Klaus,
I think it may be possible with some controllers. The Curtis 1238 looks like it is programmable to some extent. So it may be possible to get it to produce an output which tells you the motor speed, but it looks like a lot of work. It may be easier to just use the encoder to work out the motor speed. This together with the car speed from the gearbox, is all you really need. The hat switch tells you how to scale car-speed for the different gears, which is what the motor speed has to match. The difference is used via a PID controller to adjust motor speed (using the throttle/brake inputs) to the controller.
An interesting little project. I can’t wait to actually do it!
Mark
The 1238 does put out motor speed, but it’s a kind of inverted RS-232 that’s a little difficult to deal with. It also has a CAN bus interface though I don’t know of anyone using it.
We get motor speed using a Westach tachometer pickup and some ring magnets on the flywheel. It’s mounted where the starter used to be.
Jack Rickard
Hi Jack!
Glad you finally found that Yasa motor. I know i have mentioned it or the the sevcon controller here on the blog earlier. Maybe about a year ago. Anyway i have seen the motor irl and also the genV controller. The motor is very nice looking and is LC. Needs to be cooled with nonconducting fluid because the coolant is exposed directly to the coils. Might be able to get you in contact with people you can order from. Check out the swedish company ElectroEngine they have done a four Yasa motor Volvo C70 convertible.
Imagine the Yasa setup to do torque vectoring in racing.
Regards
Per
Hey guys, I came across the idea where DC motor has second AC motor hooked up to the auxiliary shaft, it will increase weight, but add benefits to use it during the braking plus 3-4% :-)… look at the 1st picture and Additional Features:
http://www.evalbum.com/837
My 2c.
-Y.