A new configuration of single-phase symmetrical PWM AC chopper voltage controller

With the increased availability of power MOSFET's and insulated gate bipola r transistors, a new generation of simple choppers for ac inductive loads i s foreseen. These new power semiconductors ease the use of forced commutati ons of thyristor snitches to improve the supply power factor, even with hig hly inductive loads. The ac controllers with thyristor technology can be re placed by pulsewidth modulation (PWM) ac chopper controllers which have imp ortant advantages. In this paper, a symmetrical PWM ac chopper designed to operate with single-phase inductive loads with a reduced number of controll ed switches is described. The operation as a variable voltage source of thi s converter is evaluated. This includes the conversion characteristics, har monic generation, harmonic distortion factor, and input power factor. By di gital simulation, these characteristics are investigated theoretically, and to correlate the measurements,vith theory, an experimental setup is presen ted to confirm the analytical analysis.