Development History of the Patented Variable Torque Motor - Expansion

More Innovations and Patents

To further increase efficiency, Messrs. Zepp and Hendershot developed a new motor construction to allow much thicker copper for the motor coils. The innovative construction separates the steel laminations for each coil from the normally one-piece stator ring.

With this innovation, a massive copper coil with very low electrical resistance can be used to boost motor efficiency. Three patents have been issued on this invention. Dyno testing of a liquid-cooled second generation motor on November 1, 2004 measured a peak efficiency of 96% and a broad range of efficiency above 90%.

Controller

To efficiently control this motor with integrated field weakening a custom motor controller was developed. The motor is driven with a three phase sine drive rated at 96 volts DC and 800 amp peak current. When the operator calls for extended speed and current is below maximum, the controller automatically applies field weakening to produce extended speed. The controller automates the shifting with motor drive functions, providing a seamless vehicle drive system for the operation.

Company Expansion

To accelerate commercialization of the motor, Rob Suedhoff, a Fort Wayne businessman and successful entrepreneur, proposed formation of a separate company that would license the manufacturing rights for the motor. The new company, Variable Torque Motors, LLC, was formed in February 2004. As Variable Torque Motors (VTM), additional and significant progress has been made.

Some examples

• 75% reduction in size of motor controller by incorporating power module technology.
• Customized power output
• Controller and motor are totally enclosed and liquid cooled using and electric pump, blower and radiator system.
• Retrofit design for on-road delivery trucks, busses, and other vehicles.
• Hybrid controller incorporates continuous ground fault interrupter (GFI) sensing of system.  If any leakage to vehicle frame occurs, the system is automatically isolated.
• The VTM hybrid system uses compact and highly efficient ultra capacitors for energy storage.
• Doubling horsepower using two motors in series.
• Common motor and controller components for three series of motors.

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