|A prototype plug-in hybrid retrofit kit is applied to a research vehicle’s rear wheels. After switching on the traction motors, the vehicle fuel economy increased from 50–100%. Click to enlarge.|
A group at Middle Tennessee State University (MTSU), led by Dr. Charles Perry, who holds the Russell Chair of Manufacturing Excellence, has developed and demonstrated a proof-of-concept for a wheel motor plug-in hybrid retrofit kit for almost any car.
The core of the system is a new wheel motor invented by Perry and Paul Martin III; four patents are pending. They took the space that exists around the rear-wheel brake structure and packaged in a 3-phase DC brushless traction motor on each rear wheel. The stator magnets are packaged all the way around the backside; these are electromagnets switched on and off at the proper intervals as controlled by three Hall effect sensors. An array of 40 permanent magnets are on the backside of the rotor.
|Design of the new wheel motor. Click to enlarge.|
When the system is actuated, says Perry, each motor delivers 200 lb-ft (271 N·m) of torque, without modification to the wheel mounts. For the research vehicle, the system uses an 80V, 100A Li-ion phosphate battery pack with dual DC brushless motor controllers (one for each wheel motor). The production version pack will be smaller, Perry suggests.
The system is targeted at lower speed and city cycle driving; at high speeds the system deactivates and is transparent to the vehicle, Perry says. Perry and his current five-member team saw gas mileage increase anywhere from 50 to 100% on a 1994 Honda station wagon retrofitted with laboratory prototype plug-in hybrid capability.
Perry is now talking with several potential investors—companies with vehicle fleets—to solicit funds to build and demonstrate a manufacturing version of the plug-in hybrid technology.
The whole point was to demonstrate the feasibility of adding the electrical motor to the rear wheel of the car without changing the brakes, bearings, suspension—anything mechanical.
We have gained proof of concept in terms of feasibility. We need quite a bit of money to have proof of product. What we’ve achieved is a demonstrated technology, not a proven technology. Investors want to see proven field-tested performance and reliability. We have to pass through this transition, from feasibility to true, viable product.—Charles Perry
Perry, who had 40 patents in a 28-year career with IBM before coming to MTSU, said a manufacturing partner has stepped forward “and is totally committed to us” and will accompany him to anticipated upcoming presentations.
Perry said Lou Svendsen, university counsel with the Tennessee Board of Regents, will join him in approaching companies that have both US and worldwide fleets of vehicles, especially those “interested in green technology, reducing carbon footprint and savings in fuel costs.”