A Novel Direct Power Control Strategy with Wide Input Voltage Range for Three-level PWM Rectifier

This paper focuses on a three-level pulse width modulation (PWM) rectifier using direct power control (DPC) strategy, analyzes the relationship between the input power source voltage, the output dc voltage and the switching table, and presents the key-point which limits the input voltage range of the rectifier. A novel DPC strategy with wide input voltage range for three-level PWM rectifier is proposed through optimizing the switching table and consummating the rules of vector switching. Employing the proposed strategy, the effective region of input voltage vector is enlarged, the rectifier achieves satisfying stead-state and dynamic performances with low input voltages while maintaining the constant dc output, the ride-through capability of the three-level PWM rectifier against the power source voltage sags is significantly improved, the excessive voltage jumps in phase and line-to-line voltages are avoided and the neutral-point voltage is balanced at the same time. Simulation and experimental results verify the validity and feasibility of the proposed scheme.