Patents by Inventor Randall A Shaffer

Randall A Shaffer 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).

  • Controller for AC motor
    Patent number: 5969499
    Abstract: A speed controller for a three phase induction motor using sliding mode control to generate estimates of stator current and rotor flux to control motor speed. The controller receives only the actual operating speed and the desired operating speed as input signals. The controller establishes linked non-linear hyperplaces containing the operating points of each phase and coerces the operating points to move along the line of intersection. A change in operating conditions causes a change in the power supplied to the phase terminals.
    Type: Grant
    Filed: September 4, 1998
    Date of Patent: October 19, 1999
    Inventor: Randall A Shaffer