Special-Purpose AC Converter Systems for Constant Horsepower Applications

The ac converter system discussed involves a design concept that results in a total cost that is competitive with dc converter systems when applied to specific application requirements. The particular application used as a reference is the limited speed range, constant horsepower grinder. This application may be satisfied by a constant voltage, adjustable frequency converter, and motor combination. First, the application requirements are presented. Next, the discussion covers satisfaction of these requirements by means of specific design as to minimize cost. Finally, other unusual aspects of the system are presented, such as the method of modifying the motor voltage during acceleration, the requirement for high voltage output, and a unique packaging design to satisfy the severe ambient conditions of the application.