Application of Analytic Signal and Smooth Interpolation in Pulsewidth Modulation for Conventional Matrix Converters

Abstract

This article proposes an alternative and novel approach to the pulsewidth modulation (PWM) duty cycles computation for conventional matrix converters (CMC) fed by balanced, unbalanced, or nonsinusoidal ac voltage sources. The presented solution simplifies the prototyping of direct modulation algorithms. PWM duty cycles are calculated faster by the smooth interpolation technique, using only vector coordinates, without trigonometric functions, and angles. Both input voltages and output reference voltages are expressed by analytic signals in the proposed direct modulation. Input voltages are represented by the rotating vector collection in the 2-D Cartesian coordinate system. All reference output voltages are located inside the triangular surface, named here as the voltage synthesis field, formed by these rotating vectors. A certain degree of reference signals placement freedom allows us to maximize the voltage transfer ratio to 0.866 with less switching compared to the optimum-Venturini direct method. The proposed solution was verified by simulations and experiments for CMC3 × k. The comparison with the optimum-Venturini modulation is included. The proposed PWM duty cycle computation approach can also be applied to multiphase CMC converters for any number of inputs as well as outputs.