A novel design methodology for low pass filter stage of a voltage source inverter

A low pass filter, an invariable constituent of a PWM based voltage source inverter, poses several challenges in its design. With a higher rating of the inverter, the volume as well as the cost of the components increases. With time, the filter design has evolved from the simpler first order filter to higher orders, the most popular being the third order LCL filters. Though the attenuation of high frequency components, offered by the higher order filters, has resulted in improved efficiency, the inherent instability of the higher order filter systems requires complex controls for proper functioning. Keeping this in mind, the paper describes the design methodology of a second order LC filter system based on certain performance indices that reflect the ratings of the components.