In-Wheel Electric Drive Company Names EV Industry Veteran Bob Purcell Chairman and CEO
06 October 2010
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| Protean in-wheel system. Click to enlarge. |
Protean Holdings Corp, a developer of advanced in-wheel electric drive systems, has named Bob Purcell its Chairman and CEO. Purcell, best known for his leadership at the General Motors Corporation with the GM EV-1, moves into this role after serving as a board director and strategic advisor to the company.
Protean Electric designs, develops and manufactures the Protean Drive, a fully integrated, in-wheel motor, direct-drive solution. Each motor has a built-in inverter, control electronics and software, targeted at small- to full-size vehicles. Protean’s in-wheel motors are based on a modular redundant architecture, in which individual autonomous submotors are controlled by associated micro-inverters and work cooperatively to deliver the total power and torque or the motor as a whole.
Protean Electric has created a cost-effective, modular electric drive system designed for a wide range of vehicle applications. Protean Electric is moving aggressively from technology development and demonstration to volume production. My goal is for Protean to set the new industry standard for electric drive systems in partnership with industry-leading vehicle manufacturers and suppliers.
—Bob Purcell
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| Individual micro inverter/power electronics modules with embedded motor control software. Click to enlarge. |
The distributed architecture offers system redundancy, as the failure of one sub-motor reduces performance but does not cause total system failure. Each sub-motor contains an embedded processor with control software that communicates with the System ECU (SECU). With the micro-inverters, heat is dissipated over a larger area rather than concentrated in a few very large semiconductors, the company says.
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| The SECU. Click to enlarge. |
Protean’s control system is a combination of an electronic control unit (ECU) and dedicated system control software, which together are referred to as the SECU. The SECU software is developed with model-based techniques using Simulink together with auto-code generation. The software can be supplied as individual Simulink modules, or as a complete control system for use on standard industry hardware such as dSpace MicroAutobox.
The SECU controls and manages motor and vehicle behavior based on a selection of system inputs. Each motor is directly connected to the SECU via a dedicated CAN bus.
The Brakes Controller function in the SECU is responsible for maximizing use of regenerative braking through interaction with an external brakes modulator, available from various manufacturers including Continental and Bosch.
When the driver applies the brakes, if the system is able to provide required braking using the motors, then the brakes controller will instruct the brakes modulator to hold-off the mechanical brakes so that maximum kinetic energy can be recovered. A failsafe system built into the brake modulator will ensure that friction brakes are applied if regenerative braking fails or if high brake pedal pressure is applied.
Protean is working on several aspects of “blending” regenerative braking and friction braking and integration with ABS systems. Protean says that it has an advantage over other electric vehicle drive systems in that in-wheel motors apply regenerative braking directly at each wheel independently, in a similar way to standard friction brakes.
Other solutions, such as the Toyota Prius, apply regenerative braking centrally, which involves transmitting braking torque through many mechanical components including differential and gears. Protean has developed a detailed Simulink model of blended braking in order to optimize the control strategy, ensuring maximal energy regeneration, dynamic stability, safety and seamless transitions between electric and hydraulic braking.
Protean is currently in production with the PD18, a motor designed to fit inside an 18 inch wheel rim. A range of other sizes are planned to support different types of passenger and commercial vehicles.
Purcell brings a long track record of electric drive experience to Protean Electric. From 1994 to 2002, he led the GM Advanced Technology Vehicles Group (GM ATV) that launched the GM EV-1. His group also developed and produced the S-10 Electric Truck and the GM Precept concept hybrid vehicle, part of President Clinton’s Partnership for a New Generation of Vehicles program. Many of the technologies that were pioneered at GM ATV are still widely used today throughout the industry in electric, hybrid and fuel cell vehicles. Purcell also served as Chairman of the GM-Ovonic advanced battery joint venture.
Prior to leaving General Motors in late 2008, Purcell was Vice President of Global Planning, Sales and Strategic Alliances at the General Motors Powertrain Group, where he was responsible for business and technology planning for GM’s global engine and transmission operations. His group also managed Powertrain’s $2 billion annual direct component sales and $1 billion technology licensing activities.
I don't like the idea of complex electronics and other motor hardware inside a wheel. Not all America's roads are created equal...hit a curb or big pothole and you are going to be hit with a major, major bill to repair or replace a motor. Also, you'll be creating a major incentive to have wheels stolen from parked cars so thieves can resell the motors.
Posted by: ejj | 06 October 2010 at 10:46 AM
I agree, it also is not clear where the mechanical braking is if these are on all four wheels. Regenerative braking can only do so much, towards the end of the deceleration you still need mechanical brakes.
Posted by: SJC | 06 October 2010 at 01:19 PM
Using 9-12 separate micro-inverters inside each motor just seems like massive duplication of the microprocessor and IGBT driver stage components.
The only time I've seen a similar approach was a backyard experimenter who used 7x RC model BLDC inverters in parallel to run a 7kw motor.
Posted by: Paul | 06 October 2010 at 02:48 PM
Mechanical braking is also provided, per the article. With powerful inductive braking, the mechanical braking can be a small fraction of the size and weight of conventional disc or drum brakes.
I propose that the motor's rotor is integrated with the wheel, thereby further save weight and increase the diameter of the motor, thereby increasing the torque to weight ratio of the motor.
Perhaps lighter run-flat polymer tires can further save weight of the wheel, and eliminate a spare tire, allowing a PHEV to have equal to or even more internal space than a conventional ICE vehicle.
Posted by: Roger Pham | 06 October 2010 at 03:43 PM
They talk in general about mechanical brakes, but do not describe where they are nor show them on the pictures. If you put the rotor in the wheel, tire repair and replacement would be problematic, any slip up and you destroy part of an expensive motor.
Posted by: SJC | 06 October 2010 at 03:50 PM
Ejj makes a good point about complex electronics in wheels.
Enron and other bankruptcies embarrass many resume's, but is "Purcell, best known for his leadership at the General Motors Corporation with the GM EV-1" a recommendation?
GM is convicted of destroying US urban rail. If the US had a comparable Eurail Pass, one could work in Atlanta, after two hours on a train lie on Pensacola Beach every weekend, and return for less than twenty dollars either way.
High speed rail was made for America, but we have oil spills, GM SUVs, promises, alumni, and crushed EV1s.
Posted by: kelly | 06 October 2010 at 04:00 PM
I have serious doubt that this concept can work, it will makes the wheel waaaay too heavy then the suspended mass will be huge and the suspension will perform poorly, each bump will shake this big mass with a huge. The concept of Michelin is much clever.
Posted by: Treehugger | 06 October 2010 at 04:16 PM
@Roger
To me, one of the most exciting things about EVs is the potential for different designs! Just think of how having wheel-hub motors, the ability to place batteries pretty much wherever you want, and the greatly reduced cooling needs affects one's design decisions.
Posted by: GreenPlease | 06 October 2010 at 04:28 PM
Just getting rid of the mechanical drivetrain gives huge design freedom. 6- and 8-wheel designs could give extraordinarily ride smoothness. All-wheel steering makes parking a breeze.
Posted by: Engineer-Poet | 06 October 2010 at 06:32 PM
@SJC,
For a permanent magnet motor with out-runner rotor, the rotor contains magnets and turns outside of the stators. In a wheel integrated with the rotor, the rotor is very simple, and simply contains magnetic bars (or poles) in the inside of the rotor, while the tire is on the outside of the rotor. During tire replacement, there is no need to touch the magnets at all. All the complicated electrical stuffs are in the hub, not in the wheel itself.
Posted by: Roger Pham | 06 October 2010 at 07:01 PM
This is exactly what I have been giving away for seven years now. I knew they would catch up someday.
I haven't been sitting still. In the meanwhile I have solved the problem of unsprung weight.
If you want to see what I first conceived, google: William Lucas Jones Hybrid.
Posted by: Lucas | 06 October 2010 at 07:36 PM
Siemens, Michelin, Protean developing in-wheel concept, but have not seen photo of working prototype. Just drawings. Volvo Recharge and Nissan i-Mev, GM tried to implement in-wheel concept. Nissan officially doped idea. What are the reasons?
Posted by: Darius | 06 October 2010 at 11:12 PM
Doing away with most mechanical moving part would simplify vehicle making and reduce manufacturing cost. In-hub e-motors are in their infancy and improved units will come out every year or so.
AWD and AWS will be common place ounce this technology is in common use.
People must be able to change (Wheels & Tires) quickly as they do today for winter months.
Posted by: HarveyD | 07 October 2010 at 08:37 AM
AeroVironment developed GM's EV1 prototype for $3 million in 1989. After that, GM used leaking Delphi lead acid batteries until 1999, when GM introduced it's NiMH batteries - which Toyota, Honda, etc had used for years with twice the performance in their EVs.
Then GM, by selling the NiMH patent to Chevron Oil, buried the EV battery and crushed the EV(1)s.
If history is a mentor, the hub motor concept is a winner, but an over complicated version is a patently red herring destined to be crushed.
Posted by: kelly | 07 October 2010 at 10:10 AM
Roger,
Have you ever seen a tire guy handle a car wheel? Care is not one of their main concerns. Now the tire spindle they put the wheel/motor on to change the tire has to be non magnetic, so every tire shop has to have at least one of these. I like the idea of putting the rotor in the wheel, but there are practical considerations.
Posted by: SJC | 07 October 2010 at 11:46 AM
One of the limiting features of most EV's is the range. Is there a way to split up the battery so that swapping out with a fresh re-charged unit is possible.
Many solar canopy plug-in units are hitting the market. It would be more convenient to swap out a solar (or wind) charged lithium unit.
$10,000 electric vehicle
http://voices.washingtonpost.com/virginiapolitics/2010/09/post_697.html
This would also help the bottom line cost to the average consumer.
Posted by: Ralph | 07 October 2010 at 11:49 AM
With 200 Wh per kilogram a 2000 Wh pack could weigh 25 pounds. After you swap 100 pounds of packs you would have energy for less than 30 more miles.
Posted by: SJC | 07 October 2010 at 12:06 PM
Time is the only sure way of telling but I feel certain that hub motors will dominate new car sales within 30 years or so. The mechanical simplicity advantage is just too compelling to be ignored.
That said, it seems very silly to put the motor drive electronics into the hub. Making the motor drive that small would be very costly. When one adds cooling difficulty, harsh environment, and added unsprung weight it seems like a total loser idea to me.
Posted by: Kevin Cameron | 07 October 2010 at 10:39 PM
The light weight wheel (rim) and tire could be attached to the e-motorized wheel hub with 4 or 5 bolts much the same as is done today. This would make rim/tire replacement as easy and as rugged as it is today.
Posted by: HarveyD | 08 October 2010 at 09:38 AM
There is the obvious point that if a rim/motor design were possible, they would be doing it. Perhaps they just want to go with what is done now. Rims are made by the millions and after market rim sales are happening as well. I really like the idea, but maybe there is more to it than meets the eye.
Posted by: SJC | 08 October 2010 at 11:54 AM
In time these could be common and reliable but the unsprung weight issue will not be resolved with the usual approach.
Infared laser or similar type road surface scanning and linear type retraction motors could remove most road irregularities from the equation.
A virtual no unsprung weight approach.
For now my rough roader will stay with the high center mounted siamese e-motor, inboard secondary disc braking and drop axle shafts. Managed by some form of long travell suspension.
With a similar front wheel design.
As per many military designs for the last 3 decades.
Heaps of regen braking please.
Posted by: Arnold | 08 October 2010 at 08:17 PM
If you look at the diagram, they have effectively done a rim motor, but it is separate from the rim. It might not add much weight for the shell and gets around any problems with wheel removal and tire changes.
This is a good design, except for the electronics in the wheel. If they can integrate a small brake that can stop the car in the final stage, it should last and do the job. The last item is power. If each motor is only 30 hp, you need a light car or all four wheels.
Posted by: SJC | 09 October 2010 at 02:36 PM
Many of the commentators above would have benefited from going to Protean's web site (http://www.proteanelectric.com/)to read more about the technology before posting.
1) The Protean Drive system uses a conventional wheel and tire that can use conventional mounting and balancing equipment. Removing the motor to steal it will be considerably more difficult than removing the wheel, especially if the intent is to not damage it or its cables while removing it.
2) Indeed friction brakes (albeit smaller) are still likely to be needed with the Protean Drive system and it can support several mechanical braking configurations, but the motor isn't the cause for this need. It is the battery that is main reason the regenerative braking energy can't always be absorbed, due to too high a state of charge, maximum charge rate limitations, or too high or low of operating temperature. Solving this problem will pave the way to all-electric brakes someday.
3) The concept of multiple internal inverters provides modularity and redundancy, benefits from a wider selection of power electronics components, and leverages the proven economies-of-scale associated with high volume electronics manufacturing.
4) Mr. Purcell is attributed to bringing the EV1 into production, along with many other technical innovations that likely flew in the face of GM's upper management. He was never implicated in having pulled the plug on the EV1 in any movies, books, or Internet conspiracies. He should be a great asset to Protean as this technology moves toward production.
5) Unsprung mass concerns are overblown, especially on mid-size and larger vehicles, as only time and test driving will prove. Damper tuning has tremendous positive effects, especially with modern day active damping technology and upcoming active suspension systems. Consider the live rear axle in a modern pickup or SUV and how much this technology could actually reduce unsprung mass.
6) Other in-wheel motor systems, such as Michelin's, use gear drives to increase torque at the wheels which causes audible gear noise and efficiency losses. Integrating the power electronics as Protean's system does offers great packaging and EMC advantages by not needing to find another place in the vehicle for that electronics.
7) There are several working concept vehicle models, as Protean has been publicly demonstrating, and as shown on their web site. The existing motor, their PD18, is just one of many models coming in their future road map, and each one is capable of more than 80 kW (>100 HP), battery permitting.
Posted by: Tom | 10 October 2010 at 09:57 AM
Dynamic braking isn't an issue of power dissipation; if you recover more power than you can store, you can always dump it in a resistor (e.g. a heater in the engine coolant loop). The big problem is that heavy braking requires far more power-handling capability than most cars are designed for. A 4000-lb car braking at 0.7 G from 80 MPH needs to move a whopping 445 kW and put it somewhere. If the electronics can handle the power of a panic stop from maximum speed, great. Otherwise you need something else, and that's going to be friction brakes.
Posted by: Engineer-Poet | 10 October 2010 at 04:09 PM
54KW @ 31 KG (motor only) plus mechanical brakes plus rim, tyre and the relevant suspension elements is very heavy. But maybe I've missed something?
Not such an issue on non-steer wheels, and that may flow through to steer wheels that are fixed geometry. In this instance we are looking at steerable.
Other interactive suspenders will be applicable to lightweight conventional linkages.
Posted by: Arnold | 10 October 2010 at 06:11 PM