Home > Automotive > Why Choose the Induction Motor? (Part 1 of 2)

Why Choose the Induction Motor? (Part 1 of 2)

September 12th, 2011

By Bob Weed, CDA Vice President, OEM

The Copper Rotor Motor : An Alternative to Permanent Magnet Motors in Hybrid or Plug-in Electric Vehicles (EVs)

It’s a time of change and innovation in the auto industry. Automotive manufacturers are looking at options to reduce fuel consumption and emissions. As a result, electric propulsion has become a popular alternative.

In the past, internal permanent magnet motors have been a popular design. But that view is evolving as automakers consider the induction motor, a potential alternative to the permanent magnet motor. These motors have comparable torque and efficiency, along with a rugged, durable design. They don’t have a drag loss when the motor turns on and they don’t lose their efficiency during high speed or low torque conditions. This makes them well suited for hybrid and plug-in hybrid vehicles. In contrast, permanent magnet motors can experience significant stator losses. These motors also require expensive controllers and rely on rare earth magnet materials.

There’s a reason the Copper Development Association is addressing this issue. We want automakers to know there’s a real advantage to using copper induction motors over permanent magnet motors for hybrid or plug-in electric vehicles.  The use of copper rotor induction motors isn’t new. The General Motors EV1, produced by the automaker in the 1990s, had an induction motor. Today, Tesla Motors, a leading manufacturer of EVs and EV powertrain components, uses the copper rotor at the core of its vehicle propulsion systems.

J.P. Strauber, Tesla’s vice president, was quoted recently as saying, “In a world where we are building millions of electric vehicles, I think the copper motor rotor will be the technology of choice to make that happen.” Tesla’s high-performance copper rotor motor delivers 300 horsepower and weighs only 100 pounds. The motor rotor and rotor stator use only copper and steel – no rare earth metals are involved.

Copper-based induction motors are 20 percent less costly to manufacture than their permanent magnet counterparts, yet provide performance advantages. The CDA supports the automobile industry by bringing our technical expertise to aide engineers and designers in the U.S. and worldwide.  If you’d like to learn more about the advantages of copper rotor motors in EVs, please contact me, rweed@cda.copper.org.


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