Research on Three-phase Hybrid-clamped Five-level PWM Rectifier

Due to the particular advantages, multilevel PWM rectifier has been widely researched and applied. However, for the diode-clamped neutral-point-clamped (NPC) topology, the problem of DC-link capacitor voltages imbalance has limited the relevant application to three-level. To solve the problem, this paper focuses on a hybrid-clamped five-level topology, which is applied in PWM rectifier, and the working modes of the converter under the condition of alternative hybrid PWM (AHPWM) modulation are analyzed. A method of calculating the equivalent capacitance of the switched- capacitor circuit is proposed. In addition, a practical dual-loop control method for the converter is discussed. The experimental results show that the five-level PWM rectifier can guarantee the DC-link capacitor voltages balance, restrain the distortion of the AC-side input current and realize power factor correction.