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Wheel motors - too good to be true?

The following is from a "Voltage Forum":

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I checked the company website:

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and found specs for their wheelmotors which seem reasonable enough

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However, the power specs for the car seem way off base for any of the listed wheel motors or any known technology, AFAIK. Particularly, the assertion of 160 bhp per wheel. The torque of 750 N-m (552 ft-lb) is close to the advertised maximum spec of 640 (160 cont), but the power is 14.4 kW, or about 20 HP, at 900 RPM. I think somebody mistook the 160 Newton torque for bhp, and ran crazy with it! Do you think the acceleration spec is believable? An actual total torque of 2200 ft-lb for a 3600 lb vehicle, with 24" dia tires, would provide about 0.7 G, and 0-60 in about 3.5 seconds.

So, aside from the overblown HP hoopla, this still looks like an impressive vehicle. It's a shame they still feel a need to design and advertise so much on the basis of raw HP and amusement park acceleration. It looks like they could have made a still impressive car with half the power and perhaps

120 MPG, which would impress me a lot more than burning rubber.

Paul

============================================================================

June 29, 2006

Dear Jim,

BRITISH MOTOR SHOW - 20TH TO 30TH JULY 2006 EXCEL CENTRE LONDON

On behalf of PML Flightlink, I would like to invite you to visit us at the upcoming British Motor Show at the Excel Centre, London. It runs from the

20th - 30th July. Please take a look at the website for more information
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We will be on stand 270.

PML will be exhibiting the new Super Mini QED, produced to demonstrate the EW series wheel motors and generator technology co-ordinated on the vehicle as a Quad Electric Drive system, together with additional new technology developed in tandem, including Energy Management Systems and In Car touch-screen interfaces.

Vital Statistics:

0 - 60 in 4.5 seconds! Approx. 80mpg! Approx. 150mph top speed! No brakes?!

I have attached a report (see below) on the new Super Mini QED specifications - it should be an interesting read.

The new Super Mini QED from PML demonstrates the future of CLEAN transportation cleverly packaged in a stylish and desirable vehicle.

QED - Quod Erat Demonstrandum

Please let me know if you can make it. It would be great to see you there.

Best regards, Chris Newman Sales Manager

PML FlightLink Ltd. Riverwey Industrial Park, Newman Lane, Alton, Hants GU34 2QW Direct Phone +44 (0) 1420 594142 Switchboard +44 (0) 1420 594140 Fax +44 (0) 1420 83930 E-mail snipped-for-privacy@pmlflightlink.com

This message may contain confidential or legally privileged information. In the event of an error in transmission, unauthorised recipients are requested to contact the sender immediately and not to disclose or make use of this information.

Super Mini QED - Quad Electric Drive

For the past 4 years PML has been quietly working on something of a literal revolution. Its QED technology is set to move the Electric/Hybrid vehicle market into Top Gear! With some notable car manufacturers releasing various embodiments of so called "Hybrid Technology" the general public is becoming more aware - at least of the terms, and to some extent, of the technology itself.

Of course the term "Hybrid" has many levels of stratification in it's realisation, starting with the "switch off the engine if the vehicle remains stationary for more than a set time" through to so called "Parallel Hybrids" which drive the wheels via the engine and gearbox as well as an electric motor powered by a battery, along with a generator fitted to the engine.

The problem with all the above remains the poor efficiency of the internal combustion engine, which even on a good day returns no more than 20% of the fuel it burns as usable mechanical energy to move the vehicle. Although IC engines can have efficiencies of up to 40% this is rarely, if ever, realised in practice due to the continuously varying loads and speeds involved in a typical "real life" journey.

Battery technology is improving year by year and there are some interesting options which look promising in the next 5 to 10 years. Today however, the battery technology is still the limiting factor in realising a full utility vehicle. Do not despair; there are ways to manage this!

It seems today that anyone with an environmental conscience has the limited choice of a Toyota Prius or a Honda Civic! Of course there are other vehicles on the market but they all require substantial sacrifice of motoring pleasure and utility if your Green conscience is to be placated.

Well this does not have to be the case any longer. The PML solution, which can be seen at the British Motor Show at the Excel centre, London from 18th July this year, strips away all of the misconceptions about electric hybrid vehicles to showcase a truly awesome car.

Take a standard BMW Mini One:

Discard the engine, the disc brakes, the wheels, and the gearbox. Add instead four electric wheels, a lithium polymer battery, a large "super capacitor", a very small IC engine with generator (so small it fits alongside the spare wheel!), an energy management system and a sexy in-car display module. Give the vehicle 3 modes of operation, Eco mode for in town/city frequent start-stop operation, Normal mode for daily commuting and equivalent ICE car operation and Sport mode for all the bells and whistles you would expect from a super car.

Result: Super Mini QED

0 - 60mph 4.5sec (Mini Cooper S around 7.5sec) Top speed (where allowed) approx. 150mph Electric only operation time 4 - 5 hours commute at 50mph or less Fuel economy approx. 80mpg (when powered by the generator) No loss of passenger or boot space Weight distribution and handling as original vehicle 3 driving modes Eco, Normal and Sport

"Look no brakes!"

All braking is performed by the wheel motors acting as very efficient electrical generators which return almost all of the energy back to the battery system. The beauty of this system is that unlike a conventional vehicle your green conscience can be quite content even when accelerating hard, since you are assured of collecting most of this expended energy should you have to slow down quickly!

ABS - forget that pulsating foot!

Because the wheels are high performance motors, ABS comes as a standard function built into each wheel's software. Now anti-skid can also be applied to acceleration since the motor can smoothly control torque delivery to/from the road in both cases. Slamming your foot to the floor results in controlled maximum torque, giving the shortest possible stopping or acceleration time.

Clever wheels!

No need for crude differential gears to share power between left and right sides. The wheels are in constant communication with each other deciding

1000 times each second how much torque share is optimum for the current driving conditions. Should one wheel detect a slippery surface and take appropriate anti-skid actions, the other wheels are aware of this instantly and adopt an appropriate compensating strategy to keep the vehicle as stable as possible.

Brake horsepower? - schmorsepower!

Each wheel develops 160bhp!! Yes that is correct, 640bhp in total! The original Mini One develops less than 100bhp with an engine that weighs nearly double the weight of the four electric wheels! Apart from wheel bearings there are no wearing parts in the electric wheels; this means the horsepower stays for the life of the vehicle - and beyond!

Charging? - schmarging!

As the battery level reduces, the rear mounted engine/generator starts to automatically top up the battery. So when you arrive at your destination you can simply park the vehicle knowing that when you return the battery will be replenished! Alternatively you can take advantage of lower cost mains electricity and plug in to recharge. Driving along the motorway to visit friends in Manchester - no need to worry about battery capacity or how to recharge. As the level falls the generator is started to sustain an average speed of 60 - 70mph with no further battery depletion.

Super capacitor - super acceleration!

Capacitors are used to store electrical energy. The difference between batteries and capacitors is that capacitors can release/absorb their energy

10 times faster than a battery. For acceleration or power boost at higher speeds the capacitor enables nitro-like performance, more than doubling the power from the battery during these events. Very efficient energy recovery means next to nothing is wasted during stop start city travel. The capacitors also allow the battery to have an extended life by smoothing out any peak loads.

Energy flow management

A significant key to super performance is optimum energy management. Continuously deciding where energy flows should be - battery, super capacitor, generator, wheels. By clever optimisation of the flows, best use can be made of available reserves, allowing a fun driving experience whilst protecting the planet.

Small engine and generator

The IC engine weighs a mere 15kg (less than 1/10th of the original Mini One engine) and delivers 15kw. A high efficiency electrical generator is fitted to the engine to provide power when the battery depletion level demands. The key point is the engine is run at a continuous speed and load - which results in optimum efficiency fuel conversion. After delivering the energy to the battery system the mile equivalent translates to around 80mpg!

In-car display

With all this advanced technology the driver needs to have clear and complete information presented to him. The in-car display module provides the latest touch screen technology with intuitive display and scroll options. Showing available mileage subdivided by battery and fuel along with boost status, the display gives comprehensive information. Of course the display shows speed and warning functions, but further it is GPRS enabled allowing:

Remote diagnosis of any fault to allow the "AA" man to come prepared Auto tracking of speed limits (optional!) Auto management of generator to prevent inner city operation History storage and system configuration interface.

PLUS:

Each of the 3 driving modes is selectable by a single touch of the in-car display. Imagine starting your journey in the city in Eco mode then selecting Normal mode as you reach the suburbs, and finally Sport mode as you hit the open road. There is no other way to make your journey! What more can be said?

Quad Quod Electric Erat Drive Demonstrandum

Summary:

Look No Brakes High power wheel hub motors Dual circuit operation High reliability electronics Anti skid braking and accelerating Torque share/traction control

High Power Wheels

160 bhp (120kw) each wheel = 640bhp total 750Nm per wheel = 3000Nm total braking/acceleration torque HI - Pa Drive technology

Provides world leading:

- Power to weight

- Reliability

- Safety

- Efficiency

Hand brake parking included in rear wheels

TMS - Torque Management system Full ABS functionality - but smooth! Anti skid acceleration control Optimum differential and torque share Full traction control All functions smooth and fast!

EFM - Energy Flow Management Manages energy flows between battery, capacitor, generator and wheels Provides torque boost at high speeds for rapid overtaking Optimises energy use/flows Allows top speed of around 150mph

ICD - In Car display Immediate selection of driving mode: Eco Normal Sport

Provides full driver information service: Speed Range Performance Status Energy flow map

Reports warnings of: Low battery Extreme temperatures Other out of limit warnings

Future option to link to GPRS allows: Journey / energy reserve matching Prediction of journey radius available Automatic speed limit control (optional!) Driving license optimised speed constraints Remote diagnosis of any system fault conditions Auto reporting of breakdowns Auto location for attending engineer

REG - Range Extending Generator

15kw continuous power allows normal cruising with zero battery impact Optimised running conditions enable approx. 80mpg equivalent fuel consumption Compact unit weighs less than 40kg total Operates automatically to charge battery when level drops to 50%

Battery system

21kw hr Lithium polymer Over 2000 charge/discharge cycles to 80% dod = 10yr estimated useful life

Super Mini QED High performance series hybrid Full four wheel electric drive + range extending generator No intrusion into base vehicle utility space Weight distribution and handling same as base vehicle No mechanical dynamic brakes No gears or other mechanical transmission Super high performance wheel hub drives Dynamic torque distribution for skid free braking and acceleration Top speed approx. 150mph

0 - 60mph 4.5sec

Super capacitors give boosted top end performance and optimum energy management

Who are PML?

PML (originally Printed Motors Limited) invented and patented the printed armature motor some 40 years ago. The printed armature motor was the first "pancake" format motor and led the world in compact high performance brushed motors. In the last 4 years, under private ownership, PML has concentrated on the pancake format brushless electric traction "wheel motor" development and wind turbine generators. This year marks the launch of several new products pushing forward direct (gearless) motor drive systems.

The mini project has been undertaken to demonstrate the super high performance now possible from PML Hi - Pa drive and QED technology lead. With very high efficiency, light weight and extreme levels of reliability PML Wheel drive systems are suited to harsh environments needing extreme levels of safety.

Set to take off in a big way, PML is a British company investing heavily in R&D to take advantage of the benefits of super efficiency lightweight wheel motor drive systems. In a global economic climate looking for steep changes in transport efficiency improvements, PML is well positioned to take the technological lead.

(Much of the data above is predicted and is dependent upon the terrain, weather conditions, driving style etc. PML has used its best endeavours to present accurate information, but accepts no liability for any errors and/or omissions).

Reply to
Paul E. Schoen
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SNIP

CSIRO developed a wheel motor having 98% efficiency for use on solar powered vehicles in the Darwin - Adelaide Solar Car Challenge. I checked out the cost a couple of years back and from memory the cheap version was some AUD50K and the expensive version was about AUD70K.

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Reply to
Ross Herbert

[hybrid car specs snipped]

Refreshing to see a car maker touting actual performance advantages, rather than the fact that they'll pay for part of the gas their vehicle will guzzle.

Okay, so it's not *actual* performance yet, but on the right track. Present "weak" hybrids are little more than a conventional drivetrain with an electric booster. Direct-drive would let one drop the tranny, clutch, differential, and weight and mechanical losses of same. Also, with per-wheel drive the tiny on-board internal combustion engine, de-coupled from the road, can then be run at optimum rpm and torque...much more efficient.

The 21KWH LiPoly battery looks like a nasty wear item -- last time I looked, LiIon cells were about $0.50 / WH.

Cheers, James Arthur

Reply to
dagmargoodboat

Motors tend to have torque proportional to their volume. There's a maximum feasible value of the B field, around 1 tesla. As you increase the diameter, you win linearly because the torque is force X distance, and linearly again because you can pack more wires into the circumference of the rotor. In addition, you win torque linearly by increasing the length. Multiplying out, you get torque proportional to volume.

That means that the only way to get high torque out of a small motor is to run it at high speed and gear it down. Disadvantage #1 for wheel motors. Disadvantage #2 is that they have terribly high unsprung mass, which makes for very poor handling, especially over bumps.

We'll have transmissions quite awhile longer, I think.

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

Disadvantage number three and the real biggie, is that a parallel hybrid can get half its peak power from the ICE and half from the electric motors.

In-wheel motors thus have to be a lot larger if all power is to be funneled through them.

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: don@tinaja.com

Please visit my GURU\'s LAIR web site at http://www.tinaja.com
Reply to
Don Lancaster

But then they were only talking about a lawnmower sized ICE so it wouldn't make much difference. I think they got some sums seriously wrong or have a lot of wishful thinking.

What is the charging efficiency of LiPoly batteries? A quick look at the Sanyo site and it was talking about a 2.15Ah battery being charged at 2.15A for 3 hours. Didn't look too promising running a small ICE efficiently so you can loose half it's output charging batteries?

Reply to
nospam

But the above wouldn't preclude a short motor of large diameter--a pancake motor--or a toroidal-shaped motor. The large diameter would provide torque, and the short and/or hollow structure would save weight.

I confess to being motor-ignorant and mostly taking the PML Flightlink people at their word. They claim 4.2Kw (5.6hp) continuous power for their model EW25/30, with a mass of 8.5Kg. Given the phenomenon of 300g CD-ROM motors run at 400W-to-1.3Kw, e.g.

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the PML Flightlink figures didn't seem outrageous.

8.5Kg *is* a chunk to add to the unsprung mass, but there are some savings too--don't forget to subtract the brake disc/drum, calipers/shoes (which PML eliminates), and axles/linkages. (Dunno how much these amount to--Google's s/n ratio was horrible.)

It would all seem to come down to how much power one *really* needs.[1]

Cheers, James Arthur

[1] I measure my Acura as needing 14 hp (10.4 KW) cruising at 60 mph (96 Kph). It has a 113 hp (84 Kw) engine--about 8x oversized--to accommodate acceleration. In turn, I calculate roughly 68 hp (51 KW) needed to accelerate 0-60 mph in 10 leisurely seconds, so at least 54 hp (40 Kw) reserve is needed in bursts. Electric motors should be good in this respect, having high peak capability.

Torque-wise my car produces 13.7 N-m peak @ 5,500 rpm, versus the EW25/30's rated 42 N-m @ stall (continuous), 168 N-m @ stall, peak (30sec), per motor.

Finally, my Acura's EPA-rated for 30 highway MPG, but I average 37, for a calculated overall gasoline-to-locomotion efficiency of 21%.

Reply to
dagmargoodboat

But the internal combustion engine (ICE) is the *last* place you want to draw peak power from, since it means the ICE has to be so grossly oversized compared to cruising requirements. ICEs have abysmal output at low rpm, necessitating a monsterous beast for decent acceleration, e.g., from a stoplight. Thereafter you're stuck lugging around a huge chunk of metal, running inefficiently at a fraction of its rated power.

The chief advantage a hybrid promises is the ability to run a much smaller ICE optimized for your *average* load, while relying on the flexibility and efficiency of the electrical motors and support system to provide peak power. Small electrical motors can provide large intermittent bursts. ICEs, I'm told, can be twice as efficient when operated at optimum torque & rpm.

Cheers, James Arthur

Reply to
dagmargoodboat
[snip]

But V8's are so-o-o-o much fun ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Varrroooommmm! We all like to go fast, but you *can* save a lot of fuel if you're willing to take a little longer winding up. With Arizona gas--seems juicier than CA gas--I got 41 or 42 mpg cruising @ 85 last time I checked.

James Arthur (who once passed Gila Bend on I-8, going about the same speed as you) (and also drove through your southern deserts one summer, 120F or so outside, with heater on max and windows wide open to cool the engine. Hot, but a dry heat ;-)

Reply to
dagmargoodboat

In what kind of a vehicle? Motorcycle ?:-)

The benefit of buying a car in Arizona is that *everything* comes standard with the "desert cooling package"... oversized radiator, electric fans.

Monday I was stuck in traffic at about 3PM in the "Broadway Curve" where I10 and US60 merge, due to a multi-car accident... debris strewn from the merge point all the way to the Broadway exit :-(

Running the A/C, the engine temperature didn't rise enough to even be visible on the gauge.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Sn-orrt!

No silly, Acura Integra.

Best, James Arthur

Reply to
dagmargoodboat

Sounds about right. 5.5-6 l/100km at 135km/h. And lots of pep.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Two updates to this topic: 1) A car-crazy pal reports that electric racers use chassis-mounted motors, with flex-shats driving planetary reduction gears on the wheels, fixing the sprung/unsprung weight problem.

2)
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Mitsubishi's Lancer Evolution MIEV. It uses four outer-rotor in-wheel motors on 20-in. wheels, each wheel-hub motor producing 50 kW and 518 Newton-meters of torque. 0 to 60 mph in < 8 seconds. Top speed ~110 mph.

Earlier in the same article: "GM showed us a couple of battery-powered S-10 pickups that had a 114-hp three-phase, liquid-cooled ac induction motor driving the forward wheels, and separate wheel-hub motors for the back wheels (Fig. 3). [...] In the new versions, the wheel hub motors provide a 60% increase in torque when the driver calls for acceleration. Each generates about 25 kW. They also add 33 lb to each of the rear wheels, which is why they aren't used in the front of the vehicle. And, they add the possibility of electric anti-skid control."

Best, James Arthur

Reply to
dagmargoodboat

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