Study of closed loop control based on double synchronous rotating frame for two-stage matrix converter under unbalanced load

Unsymmetrical output voltage in two-stage matrix converter (TSMC) is mainly caused by unbalanced load, which can be decomposed into positive-, negative-, and zero-sequence components. The representations of output voltage components are deduced both in positive- and in negative synchronous rotating frame (SRF), the problem of closed-loop control method based on single SRF is analyzed. A novel closed-loop control method based on double SRF is proposed, which used two groups of PI controllers, one in the positive SRF is used to regulate the positive-sequence components, the other in the negative SRF is used to regulate the negative components, the proposed control method can completely control both positive and negative components without error and restrain unbalanced load disturbances quickly. Numerical simulation verified the validity and effectiveness of the proposed control method.