Achieving sinusoidal rectifier input currents while minimising the kVA rating of controllable switches

A three-phase diode bridge rectifier is commonly used in many power electronic systems to convert the utility voltages into a DC voltage. Nonsinusoidal supply currents drawn by such systems are of concern to electricity supply authorities. With the objective of obtaining sinusoidal current, this paper compares three techniques in terms of total kVA rating of the controlled switches: (1) an active filter added between the supply and rectifier; (2) an active filter with a boost converter controlling the DC current of the diode rectifier; (3) a six switch, PWM power converter. Computer and experimental results of the active filter in combination with the boost power converter are presented which show the system to be an economical solution in terms of the total kVA rating of controllable switches.<<ETX>>