Nonlinear high-frequency switching filters for the DC-Side of AC/DC power converters

In most of high power DC applications, phase-controlled rectifiers are still the preferred power converter because of their simplicity and reduced cost. However, the output voltage of a rectifier contains harmonics in addition to the desired DC voltage. This paper explains the concept of the nonlinear shunt- and series-type switching filters, using high-frequency switching PWM power converters. Two new circuits for DC-side switching filtering are developed and compared to the existing topologies. The design, modelling, control and principle of operation of the new DC-side switching filters are described. The salient features of the proposed fillers are the reduced filter power converter rating, reduced size of passive elements, and the elimination of the auxiliary power supply that has been used for series-type and shunt-type active filters. All analyses and control system designs are verified with simulation as well as experimental verification.