Several small ground transportation manufacturers have gone beyond the technology discussed in the box “A Doubly Efficient Electric Hybrid” on page 33. The cars discussed require the alternator-motor to rotate the gasoline or diesel engine crankshaft in battery-operated mode, reducing efficiency. That problem can be eliminated.
Magnet-Motor GmbH of Starnberg, Germany, replaces the conventional drive train with two “hub motors”—inside-out permanent-magnet DC motors with the magnets rotating and connected directly to the wheel hubs without gears. The engine drives a large alternator, and the design offers state-of-the-art speed control, rectification, and regenerative braking with battery storage. This technology is applied in hundreds of Swiss trolley buses and in nearly all diesel European airport buses; the technology is available for all power sources.
Lockheed Martin Control Systems of Johnson City, New York, uses a similar arrangement that has an alternator, state-of-the-art control, and regenerative braking with battery storage, but one large DC motor delivers power through a drive shaft, differential, and rear axle, or through double drive shafts and planetary gears. The New York City Transit Authority is apparently pleased with the performance of these vehicles and now has a large fleet.
G. G. S. Engineering/Stored Energy Technology in Derby, UK, has taken the magnet-motor concept and placed it in a standard resilient wheel (for a light-rail car or streetcar), reducing weight and complexity. The concept should have even greater advantages for automobile applications.
Also in the UK, J. P. M. Parry & Associates of Cradley Heath has several low-floor, lightweight, flywheel-storage tramcars in trial operation for low-cost public transit, but has not yet used the hub- or wheel-motor concepts.
I suggest taking the hub- and wheel-motor concepts and reducing weight and complexity by replacing the rotating permanent magnets with rotating slanted copper or aluminum bars to form an inside-out hysteresis-nonsynchronous AC motor, that is, one with slanted rotating conducting bars allowing efficient operation below synchronous speed; the bars would be shaped to ensure efficient air cooling by fan action. US transit engineering expert William Vigrass has suggested possible all-wheel steering, “crab” berthing when standing, and the ability to follow a slightly modified rail right-of-way with automatic guidance and rear wheels following front wheel paths.
An experimental bus line in Trieste, Italy, designed by Breda of Italy, is all electric, using rails in the street that are powered only when the bus is over them. The bus has battery storage for limited off-rail capability, and does not require the rail for steering. Why not place power rails at specific bus stops and use battery power between? And why not extend the concept to an all-electric personal car system with the driver positioning his car on power rails at “filling stations” to charge the battery for, say, 500 km to the next charge? A similar French system is on trial on the Marseilles, France, tram line. Perhaps my “wheel motor” suggestion can make such a system even more practical for personal vehicles.
