Space vector modulated matrix converter with minimized number of switchings and a feedforward compensation of input voltage unbalance

This paper presents a new double-sided modulation strategy for matrix power converters based upon an indirect conversion scheme which models the matrix converter as two independent stages performing rectification and inversion. The new modulation strategy keeps the number of switchings at a minimum. This paper shows that the indirect conversion scheme contains insufficient information to achieve the minimum. The new strategy establishes a link between the two modulations. Numerical simulations as well as analytical results show a reduction of more than 10% of the switchings compared to the conventional strategy. It is shown that the indirect conversion scheme is quite useful in the analysis of the input voltage unbalance. A feedforward compensation method based upon measurements of the instantaneous values of all three input voltages is presented. It is shown that, with a further restriction on the voltage transfer ratio, it is possible to operate the power converter with balanced output voltages, even when input voltages are unbalanced.