A series resonant sinewave output filter for PWM VSI loads

Modern industry installations using power electronic conversion systems are requiring improvements in the loadside output voltage waveshape to meet demands of various operating load conditions. This paper reveals a novel series resonant sinewave output filter apparatus inserted between a pulse width modulated (PWM) voltage source inverter (VSI) and passive load or dynamic motor load. Compared with conventional LC low pass filters, the topology given gives size, weight, fast circuit dynamic response advantages and is relatively cost effective. A description of circuit operation, mathematical analysis, analytical results and experimental results is given. The power electronic component work done to push the polypropylene filter capacitors to new high frequency current limits, as well as pushing a new low loss high-frequency pot core inductor material to new current and thermal constraint limits, is highlighted.