Control of Cascaded H-bridge Active Rectifier Providing Active Voltage Balancing

This paper deals with topology of indirect frequency converter for new mining machine drive fed directly by 6kV ac power grid. The proposed topology is composed of input cascaded H-bridge active rectifier and output cascaded H-bridge inverter. The main attention is paid to control of input cascade H-bridge active rectifier especially to voltage balancing of the individual power cells (H bridge). The proposed control uses conventional PWM with shifted carriers and voltage balancing is solved separately by control algorithm. The paper describes results of the simulation tests for designed low-voltage laboratory prototype of rated power of 10 kW.