In-wheel electric motors from Protean Electric highlight a retrofitted Ford F-150 that the start-up company is showcasing at the Oct. 19-20 SAE Convergence 2010 show in Detroit.
"Since the vehicle's debut at the 2008 SEMA show, we've made a number of incremental engineering changes to the trademarked Protean Drive system, as well as other changes including new electronics, a new exterior paint scheme, new interior, and a new dc to dc converter from Delphi," said Tom Prucha, Principal Applications Engineer for Protean Electric in Troy, MI.
The 2009 model year factory-equipped F-150 had 1360 lb (617 kg) of components removed, including a 5.4-L V8 engine, an automatic transmission, a rear axle assembly, driveshaft, fuel tank assembly, and exhaust muffler and tailpipe assembly.
Four in-wheel electric motors with regenerative braking, along with friction brakes in the front, replaced the F-150's original drivetrain.
"Protean Drive is self-contained, in-wheel motor technology. Each dc-powered motor includes a built-in inverter, power electronics and software, as well as liquid cooling ports. Probably the most unique aspect is that each motor in this F-150 application has eight sub-motors," Prucha said.
The eight sub-motors can operate together or in any combination.
"This setup provides redundancy. So if one of the eight sub-motors fails, the other seven can continue to operate. The sub-motor concept also facilitates operating at optimum efficiency. For instance, if the vehicle is operating at a speed and load below the efficiency map's sweet spot, software controls can temporarily turn off a sub-motor so that the remaining sub-motors have to work harder—putting those sub-motors into a sweet spot for a net gain in efficiency," explained Prucha.
The sub-motor concept and the stator design facilitate automated assembly.
"By partitioning the motor into sub-motors, we can use smaller devices that are better suited to automated assembly techniques. The proprietary methodology we're using for the automated stator winding means we can get better 'slot-fill,' which correlates to an electric drive system with more power and better efficiency," said Prucha.
Next-generation BEV upgrades are en route.
"The friction brake system in the front uses half-shafts to connect the wheel motors to the braking system," Prucha explained. "But that will change, as we've already designed and tested an integrated friction brake for the Protean Drive motor to replace the in-board mounting that's on the F-150 test vehicle today. Protean Electric has several other friction brake solutions that will be available for future applications."
According to Bob Purcell, recently named Chairman and CEO of Protean Holdings Corp., the modular electric drive system from Protean Electric is "moving aggressively" from technology development to production applications.
Purcell's electric drive experience includes leading the GM Advanced Technology Vehicle Group that launched the EV1 electric car, the Chevrolet S-10 electric truck, and the GM Precept concept hybrid vehicle. He also served as chairman of the GM-Ovonic advanced battery joint venture.
Protean Electric engineers Andy Watts, Andrew Vallance, Andrew Whitehead, Chris Hilton, and Al Fraser are slated to present a technical paper, "The Technology and Economics of In-Wheel Motors" (paper no. 2010-01-2307) at 2 p.m. Oct. 19 at SAE Convergence 2010 conference and exhibition at Cobo Center in Detroit.