A Five-Level Converter With Capacitor Voltage Control Capability for Medium-Voltage Power Conversion Systems

This paper presents a new five-level converter with capacitor voltage control capability. The topology is relatively simple and the required blocking voltages of all switching devices are the same without the need of device series-connection, so the five-level converter is suitable for medium-voltage power conversion systems. Meanwhile, the five-level converter only needs to control the flying capacitor (FC) voltages and the capacitor voltage control can be achieved with a proposed simple control method based on the level-shifted pulse width modulation (LS-PWM), which reduces the control complexity. Simulation and experimental results demonstrate the voltage control ability and the performance of the converter under various operating conditions including various modulation indexes, power factors, steady-state and dynamic response, which verifies the feasibility of the topology and the effectiveness of the control method.