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Wrightspeed secures $5M in funding for series hybrid drive system for high-performance vehicles and medium- to heavy-duty trucks; gas turbine as extender
9 November 2010
Wrightspeed, Inc., the developer of the high-performance electric X1, has secured $5 million in a Series A financing from a private investor. The funding will be used to support the development of Wrightspeed’s Digital DriveSystem—an extended-range hybrid electric drive system targeted at high fuel consumption (e.g., medium and heavy-duty trucks) as well as high-performance vehicles. Both applications are similar in needing high power motors, Wrightspeed notes. Unlike conventional internal combustion engines, the same electric motors can be used in both high-power/continuous use (trucks) as well as high power/transient use (sportscars).
The DDS platform includes: the battery system, electric motors and drive electronics, generator control system, vehicle dynamics control, user interface and the software control plane. The system uses motors modularly, enabling tailoring to a vehicle’s specific use.
The motors are light—approximately 40 lbs (18 kg)—and high power, delivering up to 250 hp (186 kW). A DDS system can be configured with one, two or four motors. The light weight makes packaging them in high performance cars or in truck axles (replacing the differential) easier than with existing motors.
The battery system delivers and absorbs sufficient power that the generator engine load is completely de-coupled from the road load. This allows always running the generator at its most efficient operating point. In a highly variable drive cycle, this alone can show a two times gain in fuel efficiency, Wrightspeed says. The battery system delivers peak power, while the generator engine delivers average power.
For the high fuel consumption applications, the peak power is 10 or more times higher than the average power, which means the engine can be very much smaller than the engine it replaces in the conventional powertrain. In some niche applications, the generator may be omitted, making the drivesystem a pure battery EV, the company says.
The battery system is smaller and less expensive than in a pure battery EV, but much larger than in a mild hybrid. As a result, the payback time can be much shorter than in pure battery EV: the system is cheaper, yet it allows displacement of more fuel per day, because it does not have the range limitation; and more regenerative braking energy can be recaptured than in the mild hybrid case, or with hydraulic hybrids.
The cell chemistry is chosen for power density and maximum delivered energy over the life of the cell. Pure battery EVs need high energy density cells, which can’t deliver the power, nor do they last as long.)
The generator system uses a gas turbine, and has no cooling system, no lubrication system, no exhaust after-treatment to meet emission standards, and is about one-tenth the weight of a conventional piston-engine generator with similar durability, Wrightspeed says. The turbine is also omnivorous, burning almost any available fuel with only minor fuel system changes, including landfill gas at up to 7% sulfides.
The vehicle dynamics control system takes advantage of the fast, precise control over individual wheel torque and speed to deliver advances in safety at extreme levels of performance, or under poor traction conditions, or with unusual loading conditions in trucks. A further benefit is the recapture of more regenerative braking energy than conventional systems allow. Competing systems which use one motor driving a conventional differential cannot achieve any of this, Wrightspeed says.
Joining the board of directors is David Welch, Ph.D., co-founder, Executive Vice President and Chief Strategy Officer of Infinera. Wrightspeed’s announcement comes on the heels of the announcement by the US Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) of the first ever programs to improve fuel efficiency for medium and heavy-duty vehicles. (Earlier post.)
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