Solid state, reduced voltage motor starter enabling equalized input/output volt-amp ratings

摘要

A motor starter circuit for minimizing the amount of current drawn by the motor from a power source during starting of the motor through current transformation achieved by selectively controlling actuation of a plurality of high speed switches. The circuit is for use with a alternating current power source that provides positive and negative voltage alternations, and an alternating current motor. The motor starter circuit comprises a first bidirectional switch through which line current from the power source is provided to the motor, and a pair of switch-diode combinations electrically configured to carry the current in the motor when the bidirectional switch, which is controlled to cycle between an open and a closed position, is in an open position. Actuation of the pair of switch-diode combinations is controlled based on the polarity of the motor current alternation. The resulting current transformation minimizes the current drawn by the motor during starting, and enables equalized input volt-amp product and output volt-amp product. The starting current drawn is reduced from the available line current in proportion to the duty cycle of the bidirectional switch.