Copper Development Association scores well at The Business of Plugging In 2011
The Copper Development Association (CDA) is at the Business of Pluggin IN 2011, a Center for Automotive Research conference in Dearborn, Michigan to spread the word about the value of copper induction motors now used by Tesla Motors in their electric vehicles.
Today, I spoke directly with Bob Weed, CDA vice president OEM, who demonstrated the innovation of the copper motor. If the conference theme this year was cross-industry collaboration, offering attendees the opportunity to discuss the potential for growth and consumer acceptance of PEVs, then it succeeded.
“It’s a perfect opportunity for the CDA to collaborate with engineers and designers as we show how this improved technology will enhance the hybrid and electric vehicle industry,” Weed says. “Copper has always been recognized as the preferred material for conducting electricity, which is why it’s used universally in motor windings.”
Copper Induction Motors vs. Permanent Magnet Motors for EVs
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. Copper induction motors have comparable torque and efficiency, along with a rugged, durable design. Other advantages to the copper induction motor include:
1. 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.
2. 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.
3. 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.
“With these advantages, more motor manufacturers are now evaluating induction motors with cast copper rotors for future vehicles,” Weed says.
Copper Induction Motors – the Choice for Tesla Motors
Today, Tesla Motors, a leading manufacturer of EVs and EV powertrain components, uses the copper rotor at the core of its vehicle propulsion systems. Tesla’s high-performance copper rotor motor delivers 300 horsepower and weighs only 100 pounds. The stator uses only copper and steel – no rare earth metals are involved.
Tesla chose copper rotor motors because they are “rugged and have lower materials costs” than the rare earth permanent magnet motors, says JB Straubel, chief technical officer for Tesla Motors. “As we transition further from a fossil fuel economy to a renewable energy economy, electric vehicles can be a key piece of that. In a world where we are building millions of electric vehicles, I think the copper rotor induction motor can be the technology of choice to make that happen.”
How Much Copper in an EV?
1. 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.
2. More than two-thirds of the copper will be found in car’s wiring harness and electrical components.
3. Copper has the highest conductivity of any metal that can be practically used for conveying electricity.
4. Each year in the U.S., nearly as much copper is recovered from recycled material as is derived from newly mined ore.
About the Copper Development Association
The Copper Development Association Inc. is the market development, engineering and information services arm of the copper industry, chartered to enhance and expand markets for copper and its alloys in North America. More information may be found at Copper.org
TorqueNews Interview Highlights
I hit Mr. Weed with quite a few technical questions, but his explanations about copper satisfied my curiosity. One important factor centers on how we need to look at copper. You cannot isolate it; meaning you have to compare how it contributes to the entire system; in other words a systems approach.
Take for example the rotor. Aluminum is certainly cheaper, but copper provides sufficient current carrying power and heat dissipation even relative to its greater weight to allow for smaller and more powerful motors, especially replacing permanent magnet (PM) motors which rely heavily on rare earth materials. Induction motors (IM) using copper rotors can easily replace them, which is exactly what Tesla did.