Modelling, Design and Control of Cascaded H-bridge Single Phase Rectifier

This paper describes first the mathematical model of a single phase cascaded H-bridge rectifier with three modules. Secondly, a direct-quadrature (DQ) synchronous reference frame transformation is employed in transforming the orthogonal pair of the rectifier output voltage and current and their corresponding time shifted versions from stationary frame to rotating frame synchronous to the line frequency. A controller is designed based on this transformation for regulating the rectifier DC link capacitor voltages to the desired level. Simulation results show that the controller is capable of maintaining the DC link capacitor voltages to the reference values even during unbalanced load.