Patents by Inventor Robert A. Fournier

Robert A. Fournier 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 to prevent midrange resonance during operation of a multi-phase step motor
    Patent number: 7154245
    Abstract: The frequency of the pulse width modulator within a step motor control circuit is increased above a base frequency under defined conditions to enable more accurate construction of the phase current waveform for preventing mid-range resonance. The PWM frequency is stepped between frequencies by a fixed amount above the base frequency, to prevent the excitation of system harmonics and prevent step motor operational instability.
    Type: Grant
    Filed: December 20, 2005
    Date of Patent: December 26, 2006
    Assignee: IMS Inc.
    Inventors: David Coutu, Robert A. Fournier
  • Method and apparatus for independently controlling each phase of a multi-phase step motor
    Patent number: 6879128
    Abstract: The current in each phase of a multi-phase step motor is monitored and the excess phase current above the set point current, as required on a cycle-by-cycle PWM basis, is reduced thereby bringing each phase current down to the set point. The PWM frequency is automatically adjusted to maintain a minimum number of PWM edges within a portion of the current waveform. A maximum charge/discharge time is specified as a percentage of the PWM period. These provide an accurate independent current control within each phase of a multiphase step motor.
    Type: Grant
    Filed: July 28, 2003
    Date of Patent: April 12, 2005
    Assignee: IMS Inc.
    Inventors: David Coutu, Robert A. Fournier
  • Method and apparatus for improved low current accuracy in multi-phase step motors
    Patent number: 6867566
    Abstract: The sense signal, which is used to indicate that the motor phase current in a stepper motor is at the set point, is marked both before and after each pulse width modulator edge thereby reducing susceptibility to commutation noise from any phase. A mask time is created for a period before and after a PWM edge. The phase current is balanced during this mask time by removing and replacing the phase current.
    Type: Grant
    Filed: August 15, 2003
    Date of Patent: March 15, 2005
    Assignee: IMS Inc.
    Inventors: David Coutu, Robert A. Fournier