Patents by Inventor Peter W. Vanderhelst

Peter W. Vanderhelst 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).

  • Patent number: 4849873
    Abstract: Active snubber structure and method for use with an electronic power inverter to reduce turn off losses in electronic switches in the power inverter. The snubber structure includes a resistor and a capacitor connected in series with each other and in parallel with the load on the power inverter and parallel, inverse connected silicon controlled rectifiers connected in parallel with the resistor for selectively shorting the resistor.
    Type: Grant
    Filed: November 5, 1987
    Date of Patent: July 18, 1989
    Assignee: Medar, Inc.
    Inventor: Peter W. Vanderhelst
  • Patent number: 4493040
    Abstract: A computer-controlled welding apparatus includes a phase-controlled resistance welding circuit (A) for selectively conducting pulses of a welding current to a workpiece (B) and a control circuit (C) for controlling the conduction of the welding current. The control circuit includes a line clock generator (30) for determining the beginning of each voltage half line cycle and a conduction sensor (34) for determining whether or not a contactor (14) is conducting current to the workpiece. A microcomputer (40) is preprogrammed with a plurality of power factor correction curves, each of which represents weld current vs. firing angle for a fixed hangover angle. The computer is programmed to select one of the power factor correction curves. If the preceding half line cycle was conductive, the program selects the curve which corresponds to the hangover angle of the preceding half line cycle.
    Type: Grant
    Filed: June 1, 1982
    Date of Patent: January 8, 1985
    Assignee: Midland-Ross Corporation
    Inventor: Peter W. Vanderhelst