COMBINED EXTINCTION ANGLE AND PWM CONTROLLED THREEE PHASE INDUCTION MOTOR DRIVE

摘要

Conventional three phase voltage control drives suffers from disadvantages such as higher torque oscillations, low input power factor and higher dv/dt across motor at low speed. These disadvantages are more prominent in low motor speed. The present invention deals with the direct ac to ac variable voltage control drive with only four power semiconductor switches associated with diode bridge to overcome above drawbacks. The control strategy used in present invention simple and practically easily implementable at low cost. The most prominent feature of proposed drive is unity and high input power factor besides smooth speed control and power saving.