A Three Phase five level cascaded H-Bridge rectifier with zero current injection scheme

A Three-Phase five level AC/DC Converter with Cascaded H-Bridge (CHB) Converter topology is presented to achieve unity power factor and improve power quality. The CHB active rectifier is an attractive topology that allows feeding of similar or different multiple DC loads. In this paper, the AC/DC converter is controlled in Synchronous Reference Frame (SRF) scheme, such that it draws a sinusoidal line current with unity power factor from the AC source. The SRF is adopted in the system to track line current command and output voltage reference. The system model and control algorithm are described. A Zero Current Injection (ZCI) solution is presented for voltage balancing of distinct dc buses in multi level CHB rectifier. This method ensures that the dc bus capacitor voltages converge to the reference value, even when the loads attached to them are extracting different amounts of power with acceptable load power limits. Multilevel Sine Pulse Width Modulated (SPWM) scheme is used to reduce the current harmonics in the input and obtain regulated DC output. The effectiveness of the proposed control algorithm is verified by the computer simulations and validated with experimental results.