A Single-Phase Active Filter Using an H-Bridge PWM Converter with a Sampling Frequency Quadruple of the Switching Frequency

Abstract

This paper proposes a new “quad-sampling” method for single-phase H-bridge converters, which performs voltage and current sampling not only at maximal and minimal points but also at zero crossings of the triangle carrier signal for PWM control. The proposed quad-sampling method makes it possible to increase the sampling frequency four times higher than the triangle carrier frequency, resulting in reduction of the control delay inherent in the digital current controller. This paper theoretically reveals that the quad-sampling method can perform correct sampling and control of the converter current at each sampling point. Theoretical analysis derives characteristics of the proposed quad-sampling method. Moreover, the proposed controller is applied to a single-phase active filter to verify its validity, and experimental results show a good performance in harmonic compensation.