The copper rotor induction motor is the best and most practical way to power electrical vehicles. What automakers may not know – a high volume process for casting copper rotors is available, making their use a practical reality, according to the Copper Development Association (CDA).
“Copper has always been recognized as the preferred material for conducting electricity, which is why it’s used universally in motor windings,” says Bob Weed, CDA’s vice president OEM, adding that the copper industry is now providing assistance to engineers and designers to bring this improved technology to the hybrid and electric vehicle industry.
When compared to permanent magnet motors, a popular alternative in the EV industry, copper rotor motors offer the following advantages:
· Copper rotor motors have comparable torque and efficiency, along with a rugged, durable design.
· Copper rotors 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.
· Copper rotors provide an economic advantage over aluminum rotors. Although the raw material cost for aluminum may be less than copper, the motor with a cast copper rotor can be up to 25% smaller than an equivalent motor with an aluminum rotor. The superior heat conduction of copper also contributes to cost savings.
· The use of die-cast copper rotors (an improved technology that takes into account copper’s much higher melting temperature than aluminum, for example) provides an efficient, high production process.
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 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 rotor and stator use only copper and steel – no rare earth metals are involved.
“With these advantages, more motor manufacturers are now evaluating induction motors with cast copper rotors for future vehicles,” Weed says. “The copper industry is ready and willing to provide assistance to engineers and designers as they work to enhance the technology in hybrid and electric vehicles.”
Automotive Copper Facts to Consider
· The average car produced in North America has 50-55 pounds of copper in it. In a hybrid vehicle, the amount will double. In a pure electric car, the amount of copper will triple.
· More than two-thirds of the copper will be found in car’s wiring harness and electrical components.
· Copper has the highest conductivity of any metal that can be practically used for conveying electricity.
· Each year in the U.S., nearly as much copper is recovered from recycled material as is derived from newly mined ore.