The Capacitor Voltage Balancing for a four-switch three-phase rectifier using a space vector modulation technique and auxiliary signal design

In this paper, an improved controller design for a three-phase, four- switch rectifier is designed to balance the voltage of DC capacitors. Today, the four-switch rectifiers have been considered due to the reduction of the two switches to the old six-switch rectifiers. However, the dividing of the same voltage across the capacitors as well as the current balance drawn from the rectifier input is one of the challenges facing these converters. Hence, in this paper, the design of internal and external loop controllers are described step by step. Also, to compensate for the capacitor voltage, the auxiliary signal is added to the internal control loop. Additionally, since the old space vector modulation (SVM) method is unable to control the converter to the purpose of balancing the input current, an improved SVM method is proposed to balance the input current of the converter. The simulation results performed in Matlab/Simulink show that using the proposed SVM method and the auxiliary signal, added to the controller, significantly compensates the capacitor voltage and the converter input current. With sensitivity analysis, it is also shown that the controller is resistant to load variations, output, and input voltage appropriately.