|An electric traction motor (right) and stator (left) at the GM Powertrain Engineering Development Center Friday, 15 January 2010 in Pontiac, Michigan. (Photo by John F. Martin for General Motors) Click to enlarge.|
Noting that power electronics and electric machine technology as well as battery technology will be core to General Motors in its multiple paths to vehicle electrification, Tom Stephens, GM Vice Chairman, Global Product Operations announced that the company will expand its in-house electric vehicle development capabilities by becoming the first major US automaker to design and manufacture electric motors.
By doing so, Stephens said, GM will lower cost and improve performance, quality, reliability and manufacturability of electric motors by controlling design, materials selection and production processes. The first GM-designed and built electric motors are scheduled to debut in 2013 in next-generation, rear-wheel-drive two-mode hybrid technology.
The expected improvement in power density in the GM-designed and built motors for the longitudinal application of the two-mode hybrid—on a per motor basis, these machines are about 25% smaller, output is about 20% higher, and efficiency is up—will allow its application in a range of vehicles smaller than the full-size trucks and SUVs in which it is applied today, including cars.
GM will invest some $246 million in the next-generation hybrid system and a manufacturing site for the motors, and will announce the new site and specifics later this week.
In the future, electric motors might become as important to GM as engines are now. By designing and manufacturing electric motors in-house, we can more efficiently use energy from batteries as they evolve, potentially reducing cost and weight—two significant challenges facing batteries today.—Tom Stephens
GM has been building this in-house capability for years, expanding electric motor research and development, design and validation capabilities at facilities in Michigan, Indiana and California. GM also has developed state-of-the-art math-based design and computing capacity for electric motors.
GM was selected in August by the US Department of Energy for a $105-million grant for the construction of US manufacturing capabilities to produce electric motors and related electric drive components.
In a briefing, Pete Savagian, GM Engineering Director, Hybrid and Electric Architecture and Electric Motors, said that four things related to electric motors really matter to customers:
Power density. Savagian said that automotive electric motors will need about twice the power density of motors applied in machine tool drives. The company’s expertise with transmission development will help with the overall packaging, he noted.
Noise, vibration and harshness (NVH). “A lot of subtlety in the electromagnetic design gets us there.”
Quality and reliability. Comparable to that of an elevator—i.e., it doesn’t fail.
|GM has been making investments since 2003 in design, development process and validation capabilities. Click to enlarge.|
GM’s position is that exceptional power density, NVH, high reliability, and affordability with motors is only achievable by understanding and engaging the entire electric motor value chain—e.g.., down to the manufacture of the component wires. By designing and manufacturing motors itself, GM can control the design, manufacturability, materials selection and production processes.
GM will also continue to work with the best electric motor suppliers; it will not make all of the motors, but it will make some of them—and analagous strategy to other core electrification technologies.
Initially, GM is committing to building all the motors for the next-generation two-mode transmission. For the other programs, including extended range electric vehicles, plug-in hybrids, hybrids, and battery electric vehicles—which GM has been studying—the company may decide to buy the motors from other suppliers, or might elect to make them.
Different applications will call for different types of motor technology. For example, a motor used as a generator in an extended range electric vehicle is mostly going to generate off the shaft—it has to be very efficient and run at very low speed, Savagian said. For that, GM would think of a high-flux permanent magnet motor. For motors within hybrid applications that run at medium torques or in a medium speed range, GM would look at lower flux permanent magnet type motors. Motors for a BAS (belt alternator starter) application run at high speed frequently, and a different technology would be appropriate. Just as automakers now have a set of core engines, they will likely have a set of core powertrain motors.