Honda’s F1 KERS motor: 60 kW, 21,000 RPM-7.8 kW/kg-99% eff

[MitchJi]

Hi,

Complete article here:
http://www.greencarcongress.com/2010/11/hondas-f1-kers-motor-60-kw-21000-rpm-7-kg.html#more

Excerpts:

Honda’s F1 KERS motor: 60 kW, 21,000 RPM, >7 kg
25 November 2010

During the EVS 25 electric vehicle expo in Shanghai earlier this months, Honda engineers presented a glimpse into the development of an advanced high-performance electric motor that Honda had designed as part of a KERS (Kinetic Energy Recovery System) intended for its 2009 Formula One race car...

Stator Core. A three-phase, four-pole, twelve-tooth design with a double lap-wound stator and permanent magnet rotor was selected. Operating motor speed would be roughly equivalent to engine speed, with a range of 13,000 to 21,000 rpm (engine speed was limited to 18,000 rpm during the 2009 F1 season).

An initial concern, particularly given the high motor speed, was the effect of iron losses in the stator core, which is typically an AC motor’s heaviest component. Conventional grain-oriented silicon steel was not efficient enough to be used in a motor that would meet the project’s motor size and weight targets, and an iron-cobalt alloy (49Fe-49Co-2V) was used to produce the motor’s stator core laminations. This yielded a 30% increase in flux density and a 15% increase in torque.

The iron-cobalt alloy’s iron losses were further reduced via a combination of technologies. A post-rolling heat treatment reduced core hysteresis losses, and an ultra-thin oxidized insulation coating was developed, which allowed the engineers to reduce stator core lamination thickness to a tenth of a millimeter per lamination while preserving the desired iron-to-insulation ratio. These refinements reduced the alloy’s iron losses by a further 60%...

Rotor Design. Honda developed a high-coercivity magnet with an intrinsic coercivity of at least 1.1 Ma/m at 160ºC (320ºF), and tuned the magnetization angles for maximum torque. To minimize temperature increases and resultant eddy current losses, 448 magnets (28 axially, 16 circumferentially) were used in the rotor’s interior PM configuration.

Rotor diameter was reduced by employing the rotor’s shaft as part of the rotor flux circuits. A high tensile filament winding made of organic high-strength fibers encloses the rotor, preventing magnet burst at the centrifugal forces produced at the rotor’s 21,000 rpm redline. The rotor’s ceramic ball bearings were lubricated by high-temperature grease rather than oil, to simplify the oil circuit and reduce losses...

Implementation and testing.
...The final design achieved 7.8 kW (10.46 hp) of power per kilogram, close to Honda's design goal of 8 kilowatts per kilogram. Peak motor efficiency was 99% and peak generator efficiency during regen was 93%. Motor weight was 6.9 kilograms...

 

[Biff]

Thats sweet, thanks. I had been looking for something like that.

RMS power (http://www.rinehartmotion.com/) did the controller for either Mclaren or Ferrari, since they listed on their website that it was for a team that ran KERS in both cars for at least 18 of the 19 races.

 

[olaf-lampe]

I can hardly imagine how someone puts 448 magnets on a rotor. Especially the ones with same polarity are hard to tame.
Maybe they installed the raw material on the rotor and magnetized them afterwards?
I wonder how much the lamination material would cost?

Very impressive indeed 8)
Olaf

 

[Jeremy Harris]

That's also a damned good point to support the 'racing improves the breed' argument which some seem to constantly seek to challenge. Without the big bucks and time pressure driven from an F1 need, I wonder how long it would have taken the auto industry to come up with something like this?

Reading between the lines, it seems as if this isn't 'new' technology as much as improving and using existing technology in a novel way, something the Japanese seem to excel at. I wonder if the magnets are on two axes? It seems possible that they may be utilising the flux from as much of the winding as possible - normally the current flowing in the end turns of each winding is just wasting power in the wire resistance. It'd be nice to see a picture of the internals of this motor, but somehow I doubt we will for a while.

Jeremy

 

[olaf-lampe]

When you wind the motor like our outrunners; each slot seperate; the copper at the statorhead doesn't have a significant size.
When you wind the stator with overlapping coils, then you'd have a different airgap between the coils or the magnets would interfere with the wrong coil too. Therefor it doesn't make sense to use the copperheads imho.
-Olaf

 

[Arlo1]

This is very cool I was just going to post it up but you beet me to it!
Now who do we talk to about getting the motor and controler off on of these cars??????? And for that mater a BMS!

 

[peterperkins]

If I win the euromillions I'll be flying to japan with my cheque book to speak with Mr Honda :lol:

 

[Biff]

This is very cool I was just going to post it up but you beet me to it!
Now who do we talk to about getting the motor and controler off on of these cars??????? And for that mater a BMS!

Talk to RMS (http://www.rinehartmotion.com/) for the controller, as for the motor, Expect to pay around $100,000 for one of them if you could get it. The technology just isn't feasable for a decent price.

I have designed a similar motor, but limited it to around 8000 RPM, efficiency decreases to approx 98%, the weight be about 14kg for 75kW. But since the volume will also be about 2x that of the Honda motor, you still have the surface area to remove the increased heat. With more exotic laminations increasing the price from around $1000/motor to $10,000 per motor (just for the laminations), you could increase the efficiency to maybe 98.5%

That's also a damned good point to support the 'racing improves the breed' argument which some seem to constantly seek to challenge. Without the big bucks and time pressure driven from an F1 need, I wonder how long it would have taken the auto industry to come up with something like this?

Reading between the lines, it seems as if this isn't 'new' technology as much as improving and using existing technology in a novel way, something the Japanese seem to excel at. I wonder if the magnets are on two axes? It seems possible that they may be utilising the flux from as much of the winding as possible - normally the current flowing in the end turns of each winding is just wasting power in the wire resistance. It'd be nice to see a picture of the internals of this motor, but somehow I doubt we will for a while.

Jeremy

That shows the overall geometry. Just a single axle, very elaborate cooling and lubricating system. With 4 poles and 12 stator teeth it would conform to the standard winding scheme of down one slot , skip 2 and back up the next, or it could also use a concentrated windindg scheme to minimize end turns and that would be AbCaBcAbCaBc I would bet that they did the standard winding scheme as it would provide a more sinusoidal waveform, and their engineers would probably be more familiar with it and the techniques required for manufacturing.

 

[texaspyro]

If I win the euromillions I'll be flying to japan with my cheque book to speak with Mr Honda :lol:

Sorry, but you are a loser! I have received several emails informing me that I have already won... and I didn't even need to enter the lottery. However, if you are willing to pay some small taxes and administrative fees, I'll split the lucre with you. And perhaps you would like to help out a friend of mine in Nigeria. He's a real prince of a fellow... but he's currently having a small banking problem

 

[peterperkins]

I have designed a similar motor, but limited it to around 8000 RPM, efficiency decreases to approx 98%, the weight be about 14kg for 75kW. But since the volume will also be about 2x that of the Honda motor, you still have the surface area to remove the increased heat. With more exotic laminations increasing the price from around $1000/motor to $10,000 per motor (just for the laminations), you could increase the efficiency to maybe 98.5%

Interesting is it in production? Link? More details?

 

[dangerzone]

I can hardly imagine how someone puts 448 magnets on a rotor. Especially the ones with same polarity are hard to tame.
Maybe they installed the raw material on the rotor and magnetized them afterwards?
I wonder how much the lamination material would cost?

Very impressive indeed 8)
Olaf

Actually, the motor and controller were made initially by Magneti Marelli a few years ago, an Italian company which makes accessories for Italian formula one racing cars. They even made it public so you can see the inside how the electric motor is made, step by step:

http://www.gentemotori.it/Foto/Gallery/Magneti-Marelli/Il-KERS-di-Magneti-Marelli-67450/

I just thought other forum members might like that, notice how wide the magnets
are spread and the line where you can see it is made of parts for 6 inrunner 10kW RC motors...

 

[HAL9000v2.0]

I think that Fiat made model 500 with 4 of those motors. Cant find the picture now but as I remember it has 2 motors in front and two in the back,

 

[dangerzone]

Talk to RMS (http://www.rinehartmotion.com/) for the controller, as for the motor, Expect to pay around $100,000 for one of them if you could get it. The technology just isn't feasable for a decent price.

I have designed a similar motor, but limited it to around 8000 RPM, efficiency decreases to approx 98%, the weight be about 14kg for 75kW. But since the volume will also be about 2x that of the Honda motor, you still have the surface area to remove the increased heat. With more exotic laminations increasing the price from around $1000/motor to $10,000 per motor (just for the laminations), you could increase the efficiency to maybe 98.5%

Well, $100,000 is a lot of money and I wonder if the cost of such a motor would be rational..?

On the other hand, there is a cheaper solution to having such an electric motor. If anyone has seen Hal's Collossus 12kW motor they have noticed they can be stacked together onto the next motor's shaft thus connecting electric motors in series. If the Colossus would have been made with a Mumetal core that would have reduced the weight to some 2.5kg per motor, 6 of them would then produce 72kW in a 15kg package. Even if such a motor would cost some 1000$ as the Predator 37 (which has a Mumetal core) and 6 of the 36FET infineon controllers some 3000$ you are still at 1/10th of the $100,000 budget. If u don't mind the weight then the Colossuses are even cheaper at some 500$ a piece (5kg each, 30kg total) which could be ok even for a small racing car.

Are there any Mumetal laminations that are affordable to be used in such a concept..? They are quite expensive here in Europe, I know Siemens is selling them for a lot of money and I was just wondering if someone in the US or China has better or more reasonable prices..?

 

[Jeremy Harris]

They have an interesting way of getting a good copper fill, using cut copper plates welded together to form the "windings". See these photos on the site linked to above:

http://www.gentemotori.it/Foto/Gallery/Magneti-Marelli/Il-KERS-di-Magneti-Marelli-67450/index.html?p=3

I recall that the Lynch motors used a similar system of cut out plates bent into a U shape and soldered together at the ends to make the windings. I can see how this is reasonably easy to do with an axial flux design, but to do it with a radial flux motor takes some ingenuity.

Jeremy

 

[Biff]

They have an interesting way of getting a good copper fill, using cut copper plates welded together to form the "windings". See these photos on the site linked to above:

http://www.gentemotori.it/Foto/Gallery/Magneti-Marelli/Il-KERS-di-Magneti-Marelli-67450/index.html?p=3

I recall that the Lynch motors used a similar system of cut out plates bent into a U shape and soldered together at the ends to make the windings. I can see how this is reasonably easy to do with an axial flux design, but to do it with a radial flux motor takes some ingenuity.

Jeremy

Ecycle uses aluminum wedges and custom formed end-turns, to create single turns per slot.

http://www.ecycle.com/motorgenerator/SolidSlot.htm

Their motor has very small inductance and resistance and a high kv, which is why I suggested their controller technology might be suitable for the colossus controller development.

Increasing the slot fill is one way of increasing efficiency, but at such high frequencies core loss is very significant so increasing copper fill is only marginal. For example in the simulations of my motor, increasing copper fill from 65% t0 85% increases efficiency (at max RPM and torque) from 88.5% to 88.7%

Well, $100,000 is a lot of money and I wonder if the cost of such a motor would be rational..?

Not Likely

On the other hand, there is a cheaper solution to having such an electric motor. If anyone has seen Hal's Collossus 12kW motor they have noticed they can be stacked together onto the next motor's shaft thus connecting electric motors in series. If the Colossus would have been made with a Mumetal core that would have reduced the weight to some 2.5kg per motor, 6 of them would then produce 72kW in a 15kg package. Even if such a motor would cost some 1000$ as the Predator 37 (which has a Mumetal core) and 6 of the 36FET infineon controllers some 3000$ you are still at 1/10th of the $100,000 budget. If u don't mind the weight then the Colossuses are even cheaper at some 500$ a piece (5kg each, 30kg total) which could be ok even for a small racing car.

Are there any Mumetal laminations that are affordable to be used in such a concept..? They are quite expensive here in Europe, I know Siemens is selling them for a lot of money and I was just wondering if someone in the US or China has better or more reasonable prices..?

I haven't found any suppliers. There must be a reason they are priced so high, either they are hard to make or they don't offer a great increase in performance in the normal electrical steel application. If you can find a data sheet to get a BH curve, I can add the material to FEMM Library then I can see what the decrease in core loss would be with Mumetal core in my motor design.

 

[GCinDC]

not sure if this is the same forumula one race car, but a sweet video with animation of the regen braking and booster...

here's a teaser photo:

 

[Hillhater]

Latest intel on this Magneti Marelli system, which is being used by several of the F1 teams, indicates that they have further reduced the weight by 30% and increased the operating speed to near 40,000 rpm !