Emerson Will Build Electric Bike Motors

DN Staff

July 18, 2005

3 Min Read
Emerson Will Build Electric Bike Motors

In what may be a nod to the future of personal transport, motor manufacturing giant Emerson inked an agreement in June with Dulles, VA-based WaveCrest Laboratories to help the design company with its motor development and commercialization efforts.

"We have a great technology but needed high reliability and lower cost," says WaveCrest vice president of motors and operations, Tim Hassett. Emerson's reputation for manufacturing and high process control promises to deliver both, he says.

Emerson and WaveCrest engineers have been working together for over a year already, according to WaveCrest communications vice president, Tom McMahon.

Followers of electric propulsion will recognize WaveCrest as a pioneer of motors for rugged on- and off-road electric bikes. The company's Adaptive Motor System uses a multi-phase, dc brushless design that places the stator at the machine's central axis, reversing the customary rotor-stator arrangement and creating what's known as a hub-type design. The rotor revolves around the central stator, making convenient points on which to lace spokes.

The motor delivers high torque and efficiency throughout its speed range, due in part to a power electronics module that drives a series of independent electromagnets in the stator. A digital signal processor assesses motor position, torque demand, and energy availability before instructing the power electronics how strongly and in what sequence they should excite the electromagnets to produce the right match of speed, torque, and energy use. The design outperforms by as much as three times the heat management of traditional motor designs, Hassett said.

WaveCrest sells the motors in its line of Tidal Force electric bikes and even offers a conversion kit for DIYers. It anticipates big Asian demand for the bikes, particularly in Thailand. The first 10,000 motors will probably be made in the U.S., Hassett says, to flatten out any bugs in the manufacturing process. Production will then likely head overseas, he adds.

A 10,000-unit order is comparatively small for a motor maker of Emerson's magnitude, according to Mark Gallion, president of the company's Automotive and Precision Motors division. Ordinarily, the company shies away from small orders because of their potential for disrupting full-scale production.

The WaveCrest agreement does mean a possible presence for Emerson in electric vehicles-something it's skipped so far with its concentration on big volume appliance and air conditioner applications. And the demand for electric vehicles hasn't grown large enough to justify much attention from the industrial giant. Not yet, anyway. But the agreement sets up a convenient way for the St. Louis-based manufacturer to dip a toe in those waters. It also gives Emerson a chance to build Asian awareness of its brand, Gallion says.

Tidal Force bikes use 750 or 1,000W WaveCrest hub motors on the rear wheels to reach speeds of 25 mph. A NiMH battery pack mounted on the front wheel can power the machine for 20 miles between charges.

High torque at zero and low speeds suits the WaveCrest motor well to electric vehicles. Low voltage operation lessens the thicket of regulatory red tape that the manufacturer must cut through.

For more information on WaveCrest, check out the link below:/ http://rbi.ims.ca/4394-518

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