Hub Motor speculation...

[cobraphx]

Ran mentioned being disappointed by the design loosing the Hub motors in another thread. That spurred me to look and see what I could find about the PML Flightlink Motors...


What has really thrown a wrench into the works is that the V-1 was originally conceived to be powered by PML Flightlink hub motors. They're small, simple, powerful, and they leave the whole power pod area free to hold batteries, genset, and electronics.

Many months ago, Ian decided that those motors were not, in his words, "ready for prime-time." Strangely enough, though, the Lightning GT in England is going to use them. One would think, that if they're good enough to use in a $200,000, high-performance GT, they should be good enough to use in a $20,000 3 wheel tilter. Volvo is looking at them too. The logical conclusion is that something fell through in the PML deal (and I'd love to know the details on that), not that they're not good enough to use.


I wouldn't be too tough on Ian for the PML Flightlink motors. Notice the ONLY vehicle moving to production using those motors is £150,000car ($265,000); morethan double the price of the Tesla and ten times the price of the V1. I'm sure pricing isn't the only thing Ian considers, but I'd guess that Ian weighs pricing and availability fairly heavily when evaluating whether something is "ready for primetime". In a $25,000 vehicle you can use two $7,000 hub motors and expect to be able to make it to market. Here's a quote from Jan 2007 about the PML Flightlink Electric Mini Cooper - Car News (http://www.caranddriver.com/reviews/hot_lists/car_shopping/green_machines/pml_flightlink_electric_mini_cooper_car_news)
.
This 640-hp Mini exists just to get our attention. According to PML, the Mini cost about $350,000 to build, but the motors and their casings were handmade. Mass-producing the motors and control systems could bring the price down substantially, and only two of the powerful motors would suffice in most applications. PML hopes to hook up with a car manufacturer or investor seeking to enter the electric-car business.

The motors were in a $350,000 car, now in an upcoming $265,000... seems to be a while longer before they are in a price range VV can afford to put them in the VV. In a quarter Million dollar car, you can afford to use hand made (expensive) electric motors. I have seen no info yet about PML actually setting up a volume manufacturing line for the PML Hi-Pa Drive (http://www.pmlflightlink.com/motors/hipa_drive.html) motors.Maybe the Zap or Volvo deals will allow them to build manufacturing capacity and reduce costs.

Seems that these wheel hub motors are stuck in the chicken and egg stage, they can't afford to build volume MFG without a large order, and no one can a large order until they can prove they can produce them in volume. This is the same place a lot of the Lithium Battery companies are in. EnerDel has a great battery, but it's to expensive because they don't have volume mfg yet.

[Lumberjack]

Close. The actual problem is proving there is a viable market for the motors and proving that they can be produced for a price usable to that market.

[waboom]

Also, there's this blurb from AutoBlogGreen (http://www.autobloggreen.com/2008/01/23/zap-working-with-a-chinese-company-on-in-wheel-electric-motors/), back in January:


Recently, I wrote a post that talked about Volvo's statement that they were working exclusively with PML (a company that makes in-wheel electric motors). I found this concerning because I thought PML was working with Zap on the Zap-X, a Lotus-designed, affordable, normal-looking electric car. I contacted Zap Communication's Alex Campbell, who checked with Zap's CEO Steve Schneider about Volvo's statements. Zap says they are in a relationship with PML but only on three-wheeled vehicles. As for four-wheeled cars, Zap tried but it looks like PML went with Volvo. Zap has moved on to a Chinese company that they say is not only cheaper than PML but can provide in-wheel electric motors sooner. So there is no confusion, here is exactly what Zap says:

We signed an exclusive agreement with PML on 3-wheelers and at the time were negotiating with them on other vehicles. We have since partnered up with a company in China with rights to their wheel hub motors. The significance is that the wheel hub motor that we have acquired is currently working in application and we believe will be commercially available within a shorter period of time than PML's. It is my understanding that the PML motor has still yet to work in any automotive application. And they are expensive so it would need to be manufactured in China to stay competitive.

[Source: Alex Campbell from Zap]

So if Zap found PML's hub motors expensive, I've got to imagine that VV would to!

Note that it doesn't really clarify which side the "exclusive agreement" on 3-wheelers applies to - either Zap will only buy from PML, or if the only 3-wheeled vehicle company PML will supply is Zap. If it's the latter, then that would kill VV's chances of using the PML units, so they decided to move on to a different engine technology.

I understand that it seems Zap has given up on using PML, based on this posting, so that could leave VV free to pursue them again. However, this far along in the process, they probably don't want to re-engineer the powertrain for the V1. Maybe in the V2.....

[cobraphx]

It looks like no one has been successful bringing the PML Flightlink Hi-Pa motors to market in an affordable vehicle yet. I do hope they can bring them into the market into vehicles most of us might consider buying. But it seems like it will be a few years before this can happen.

Not exactly a poor reflection on Ian, several companies with a lot more experience producing electric vehicles have projected using PML's hub motors and later recanted.

[RAN]

OK. I was under the impression that PML had the motors built and available... not that they still had to be hand-built with the resultant high cost. My bad.

[RAN]

The only problem I'm aware of with the PML hub motors is, there's no way to incorporate disc brakes with them. I don't know how much stopping power they can provide in regen mode, but if all 4 wheels have one, it should be quite a bit. Anyone have more insight on this?

[MVRacing]

The only problem I'm aware of with the PML hub motors is, there's no way to incorporate disc brakes with them. I don't know how much stopping power they can provide in regen mode, but if all 4 wheels have one, it should be quite a bit. Anyone have more insight on this?

RAN,
Can't find the article now, but I was reading that the PML system was MORE than adequate for full braking. They had incorporated a parking brake, but the biggest problem was overcoming peoples perception that they needed an additional baking system. It seems some were hesitant to have only electronic braking. The old fly by wire fears.

[RAN]

Thanks MVR. In that case, it seems that anybody who drove one would be reassured once they tried it out.

It certainly seems like PML has a winner... maybe when the Lightning comes out, it will give them the exposure they need.

It's really frustrating to see technology like this floundering. The use of hub motors would free up enough space in a normal car to allow enough batteries/ultracaps for decent range and decent performance <sigh>

[Lumberjack]

Electronic braking is very effective by itself BUT.... Safety may demand the inclusion of a emergency brake.

[cobraphx]

I totally agree Ran, there are several companies like PML Flightlink that have great and well thought out designs, but not the manufacturing capacity to build the product at a price price point low enough to penetrate the market in a significant way. Several of the advanced automotive Lithium battery manufacturers are in the same position. A123 got a foot in the door with the DeWalt deal, but companies like AltairNano and Electrovaya have great Lithium chemistries, but aren't in volume production (of those chemistries) yet.

[WarpedOne]

>> biggest problem was overcoming peoples perception that they needed an additional baking system

Nope, biggest problem is legislation. If law demands it, you're screwed.

[JoeU]

The issue might be- How do you keep a parked vehicle with wheel drives from slowly rolling down a hill?o:o:p:s12j:a:w:drop(((1 A resistive element will only do so much.du:n:n:o(

[cobraphx]

For rolling down a hill, a simple parking brake mechanism will take care of that. But a requirement for dual circuit hydraulic brake system, would throw a wrench in the works. Which in itself doesn't make it impossible, but certainly raises the cost and complexity of hub motors.

I haven't looked up the Arizona Motor Vehicle code lately for braking system info. So, I'm not sure what is required on a state and federal level for braking systems these days. Hopefully there is enough flex in the definitions to allow magnetic motor braking.

[RAN]

Hopefully there is enough flex in the definitions to allow magnetic motor braking.

Legislation just has to be changed sometimes to accommodate new technology. I think that hub motors could very well be the wave of the future for EVs. Shame to see them stopped by outdated laws.

[ppi]

this product is a motorcycle it requires only two wheel brakes, the 3rd for this product could be a, ebrake for parking,drum,friction

[Dutchy]

If there are brakes on a maglev train that does 300+ mph, I think a VV would not pose a great challenge.

Normally the brakes on a hub motor work in regen mode, but for emergency purposes I guess you can also put it in reverse and hit the accelerator... this poses an interesting problem: how is the driver on the rear side going to prove you hit him instead of the classic way (him hitting you). Will skidmarks suffice ?o:o:p:s12

[waboom]

PML Flightlink has posted a page (http://www.pmlflightlink.com/news_volvo.html) talking about the Volvo Recharge QED. On it, they talk a lot about braking, including that the only need for mechanical brakes is for parking. Since the Volvo is shown with 4 in-wheel motors, PML (or Volvo) must have figured out a way to integrate the wheel motors with a mechanical brake, either e-brake or parking brake.

[waboom]

They also posted a youTube video of the Volvo with PML in-wheel motors in action (sorry if this was already posted elsewhere):

h0niFw9X3wg

[cobraphx]

If there are brakes on a maglev train that does 300+ mph, I think a VV would not pose a great challenge.

Normally the brakes on a hub motor work in regen mode, but for emergency purposes I guess you can also put it in reverse and hit the accelerator... this poses an interesting problem: how is the driver on the rear side going to prove you hit him instead of the classic way (him hitting you). Will skidmarks suffice ?o:o:p:s12

The motor controller and software will be able to prevent anything like going into reverse while braking from actually happening. The motor controller knows the speed of the vehicle and the rpm of each of the motors, it will control the braking force of each wheel just as ABS does now.

Electric motor braking has been used on diesel-electric locomotive for years now, in that industry it's called dynamic braking. The train uses each traction motor to generate electricity (and thus drag) to slow the train and then converts the electricity to heat and dissipates that with fans. This is why some locomotives you see have a lot of fans along the top of the locomotive body. For a vehicle like the V1, we just need to store the electricity back in the battery. Assuming the battery technology chosen can sustain the charge current to provide maximum braking power, there will never be a reason to try and run the motor backwards under braking.

[RAN]

I read that page where they discussed braking, but I hadn't seen the video. Thanks waboom! I would totally consider buying one of those. I never liked the C30 before, just because it's FWD, but this solves that problem (and others) nicely!!!

[RAN]

Electric motor braking has been used on diesel-electric locomotive for years now, in that industry it's called dynamic braking. The train uses each traction motor to generate electricity (and thus drag) to slow the train and then converts the electricity to heat and dissipates that with fans. This is why some locomotives you see have a lot of fans along the top of the locomotive body.

It sure seems like a waste to convert it to electricity and then into heat. :-{(]


For a vehicle like the V1, we just need to store the electricity back in the battery. Assuming the battery technology chosen can sustain the charge current to provide maximum braking power, there will never be a reason to try and run the motor backwards under braking.

Ultracaps could be used in normal situations to be able to recapture that much braking energy... but real estate in the V-1 power pod is about as scarce as apartments in Tokyo. I really don't know if they could find room for them.

[cobraphx]

Besides the V1 and Volt, the Recharge is on the short list of cars I'd seriously consider if it makes it to market. Now if PML can gear up and make the motors in volume quantities at volume pricing, they can certainly be a game changer.

It certainly simplifies the braking system, requiring no extra parts from those required to move the vehicle. A hydraulic brake system has hundreds of components that aren't required to move the vehicle, only to stop it. The Unsprung weight issue isn't as much of an issue as some will make it out to be. While it does weigh 21kg, you are removing the wheel hub, axle, brake drum/rotor, brake pads, calipers, spindle and CV joints. While these parts don't add up to 21kg in most cases, the loss of those parts means that you are not adding 21kg more unsprung weight than with a comparable car.

[RAN]

Exactly. And 21 kg is the total weight of all four hub motors and controllers, IIRC. So while it does add a little unsprung weight, it's probably only in the neighborhood of 2-3 kg/wheel, and look at all the space it frees up in the rest of the car for batteries/ultracaps and a genset! Not to mention the power/handling advantages. A game changer indeed... which is probably why they're having so much trouble getting them into production :-{(]

[ziggy951]

Does anyone know of a report or study as to the ability of these, or any other in hub motors, over a period of time...say 1 year or more? Just curious if they have done long term testing on these things or if the first ones will be the guinea pigs. I read a while back that these types of devices really could not stand up to the harsh characteristics of a daily driven vehicle and that was why they weren't being used yet. Has this changed recently? I would hate to have to replace in hub motors on an EV as often, or even twice as often, as a battery in an ICE. Otherwise, they do make far more sense, from a control perspective alone.


Z

[cobraphx]

I haven't really seen anything like that publicly released yet. That may have also been part of what Ian was considering when he said they weren't ready for primetime yet.

[ziggy951]

I actually did research on this about 5, maybe 6 years ago in college. It was a white paper from some European group. It was so long ago I dont recall their name or the report name. If Ian suggested the same then I would suspect they really arent ready for such use. The problems I read about related to the constant shock they received from being only a tire away from the road. This led to many problems with parts bending, breaking, and getting loose. Especially on American roads, I can see how this could be a problem. Hit a pothole and you have to replace a $7000 part, yeah real fun. I asked because I would be interested in that research if they had come up with a solution as that would be fantastic.


Z

[waboom]

I know that most (all?) car testing facilitits include some varient of the "cobblestone track", where a vehicle can be subjected to a very uneven roadway to test the suspension and to see that all vehicle components have a "tight fit". I would speculate that Volco has already subjected it's car to the cobblestones pretty thouroughly, and possibly redesigned the suspension to accomadate this issue. Hopefully Volvo will shed some light on this at the auto show.

[RAN]

There's really only 1 moving part in those motors other than a couple bearings. Not a lot to break. I can see where perhaps the seals might need to be checked every few years, but other than that, I don't know why they wouldn't hold up.

[ziggy951]

Moving parts is only part of the issue. It is the increased load on all of the bearings of that moving part that take the massive amount of abuse when you hit a pothole, or run over the cobblestone track at a testing facility. This is where some of the problems I read about occured. The increase in load during these circumstances was leading to massive failures. Think about connecting a small engine directly to a wheel. Think about the severe duty those bearings would have to endure on a daily basis. They just arent made for it. Like I said though, I hope they have or can overcome these issues and may have with recent tech.



Z

[ppi]

My God does any company do any real world testing anymore, a computer is only going to tell you so much, i see it all the time in my business i say guys you must test for this people will do this or that, they just look like deer in the headlights??? a million dollars later they go ahhhh you were right? i take that back they won't say anything just run more test.

[RAN]

I've never seen them done that way, and I don't know if it's possible.

VV took a gamble that the hub motors would be ready for prime-time when they were ready to use them... I'm really sorry that one didn't pay off.

[Sanity]

I just saw a "how it's made" on segways. I think that's what they're called anyway. But they used hub motors. Of course segways have practially no weight and a max speed of 40mph, but they seem to be pretty reliable. Still don't get how they don't just fall over.

VV is already making a pretty big step in transportation. I think they're better off sticking to a more tried and true drive train until they're up and running well. Then maybe some more innovation could be introduced.

I wonder what the news of that new transmission for the Tesla could mean to VV. They gained quite a few mpg's just by re-designing the gearbox.

[MVRacing]

From Autobloggreen,
PML Flight link, the producers of in wheel hub motors has filed for chapter 11 bankruptcy. This affect a number of vehicles ... ZAP Alias, the Lightning GT, and others.
Hopefully some copycat will be able to takeoff with the design.

[waboom]

At least it's Chapter 11 (reorganize the company while holding off the creditors) instead of Chapter 7 (liquidate the company.) Hopefully PML can get its act together and emerge from this a viable company. I still think in-wheel motors is the way to go with EV vehicles, and PML has the best implementation that I've seen so far.

[RAN]

I hope PML survives as well. It's really a shame that PML and eVionyx can't get together with a start-up company that has the $$ to get their respective balls rolling. Hub motors and zinc-air fuel cells is about the best combination we're going to see until the technology and infrastructure exists to charge EV's on the run while they're driving down the road.