Feedback Control Strategy to Eliminate the Input Current Harmonics of Matrix Converter Under Unbalanced Input Voltages

It is generally considered that feedback control of input currents in the matrix converter (MC) is hard to be realized due to the coupling of input control and output control, which reduces the degree of freedom and robustness. Moreover, under unbalanced input voltages, the coupling also results in severe distortion of input currents when the commonly used feedforward compensation control method with fixed input power factor is adopted. To address these two issues, this paper proposes a feedback control strategy on the input side of MC. This strategy is based on a control method which can modify input reference currents. The input control strategy is embedded into the output control strategy and thus is the inner loop of the system control. The input-side controllers can be designed to achieve expected input control objectives and maintain the output performance at the same time. On this basis, resonant controllers are applied to regulate input currents and instantaneous active power, so as to directly eliminate the input current harmonics and meanwhile ensure the load absorbing constant active power under unbalanced input voltages. The validity and feasibility of the proposed strategy are verified by the simulation and experimental results.