Patents by Inventor Ed Piedra

Ed Piedra 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).

  • Method and apparatus for encoderless operation of a permanent magnet synchronous motor in an elevator
    Patent number: 6492788
    Abstract: A permanent magnet synchronous motor is controlled using d-axis current and q-axis current along with respective d-current and q-current feedback loops. The speed and position of the motor are determined by injecting a first signal into the d-axis current and observing the response in the q-current feedback loop. Part of the q-current feedback signal is demodulated with a second signal which is 90 degrees out of phase from the first signal. The demodulated signal is preferably sent through a low pass filter before being received by an observer controller. The observer controller outputs a position estimate which is used to modify the d-current feedback signal and a speed estimate which is used to modify the q-axis current.
    Type: Grant
    Filed: November 10, 2000
    Date of Patent: December 10, 2002
    Assignee: Otis Elevator Company
    Inventors: Ismail Agirman, Aleksandar M. Stankovic, Chris Czerwinski, Ed Piedra