The Lincoln Electric Company

Scott Joseph Schraff

Keith Leon Clark

Denis Michael Osowski

A method and system of controlling the output current/voltage characteristic curve of an engine driven alternator welder with a maximum open circuit output voltage, including a rotary engine, a three phase alternator, a rectifier bridge having a number of electronic switching devices for directing current to the output at an operating point determined by the firing angle of the switching devices, a sensor for sensing output current, a sensor for sensing output voltage, and a microprocessor output control device for controlling the firing angles of said switching devices in response to the sensed current and sensed voltage. The method and system comprise a device for creating a desired fixed slope operating current/voltage characteristic curve; an arrangement for sensing the present operating current/voltage point of the welder; and, a control for changing the firing angles of the switching devices to shift the current operating point to a new operating point on the desired, fixed slope current/voltage curve of the welder. Preferably, the switching devices include an SCR for each phase of the alternator.

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Lakewood, OH, United States of America

Scott Joseph Schraff