Integrated Control methods for asymmetrical cascaded H-bridge rectifier

The hybrid cascaded H-bridge rectifier (CHBR) with suitable modulation is superior in the performance for its ability to synthesize more levels at ac side. The structure of combing hybrid CHBR topology and the hybrid H-bridge inverter is applicable for AC/AC converter for aircraft applications, solid state transformer (SST), and so on. This paper proposes two kinds of modulation methods and corresponding control strategies applying to hybrid CHBR. First the control strategy for traditional hybrid modulation is proposed. Then a kind of quasi unipolar carrier disposition pulse width modulation (CD-PWM) is put forward to avoid the problem existing in hybrid modulation. Simulation verifies the adopted modulation and strategy.