Power factor improvement of single-phase ac voltage controller employing extinction angle control technique

The general study of power converters is to improve the overall efficiency of the power system by some advanced methods of control techniques. Forced commutation of the power semiconductor switches leads to improved power factor in dc converters. Similar techniques may be applied to improve the performance of ac controllers. For example, an ac controller can be used to adjust the stator voltage of an induction motor running under variable load in order to maintain better efficiency. With the present semiconductor technology (MOSFET's, IGBT's, GTO's and improved bipolar transistors), many solutions exist to alter the power factor of dynamic ac loads through an ac controller. In this paper, the performance evaluation of the extinction-angle control technique has been illustrated as applied to a single-phase voltage converter by examples of static load and the widely used single-phase induction motor to verify the feasibility of the proposed technique. Observations on power factor, displacement factor and motor efficiency make up the results of this work.