Patents by Inventor Donald E. Letterman

Donald E. Letterman has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Motor speed control by measurement of motor temperature
    Patent number: 4626753
    Abstract: A process for controlling the speed of an electric motor. A reference value of motor temperature is provided and directed to a summing junction. The actual temperature of the motor is sensed and also directed to the summing junction. The two values are summed and employed as a reference of motor current. This reference is directed to a second summing junction while the value of actual motor current is sensed. The actual value is also directed to the second junction. These last two values are summed at the second junction to provide a reference for adjusting motor speed.
    Type: Grant
    Filed: October 19, 1984
    Date of Patent: December 2, 1986
    Assignee: Aluminum Company of America
    Inventor: Donald E. Letterman