SPWM control based on compensation function for matrix converter

Non-controlled rectification and SPWM (Sine Pulse Width Modulation) are applied to the virtual rectifier and virtual inverter of matrix converter equivalent AC/DC/AC model respectively. Virtual rectifier generates fluctuant DC voltage when symmetric or unsymmetric three-phase voltages are supplied. In order to eliminate the effect of the fluctuant DC voltage on the SPWM output voltage and current of virtual inverter, the compensation function is deduced for modulation wave based on the concept of switching function. The principle is that, a sine wave, which follows the fluctuant DC voltage with reversed polarity, is injected to the modulation wave to eliminate the low harmonics of output voltage. This method is also applicable to unsymmetric input voltage condition and its realization is very simple. Simulations with Matlab/Simulink show that, high quality output voltages are obtained under both symmetric and unsymmetric three-phase input voltage conditions, which verifies the validity and effectiveness of the proposed control method.