Topology and Control of a Novel Voltage Self‐Balancing Four‐Level Converter

Aiming at the problems of complicated capacitor voltage control methods and poor dynamic voltage balancing capability under unbalanced working conditions in traditional multilevel converters, this paper proposes a voltage self‐balancing four‐level converter topology. The topology achieves voltage self‐balancing of both flying capacitors and DC‐link capacitors through structural optimization. Meanwhile, it significantly enhances dynamic voltage balancing response under unbalanced conditions. A mathematical model of the proposed topology is developed, and the pulse width modulation signals are analyzed using double Fourier transform. This analytical framework enables a systematic investigation into the voltage self‐balancing mechanism. In addition, an enhanced carrier cascade method is proposed in this paper. By selecting specific switching states, the capacitor voltage self‐balancing capability and dynamic voltage balancing capability of the topology are guaranteed under different operating conditions. Furthermore, compared with 4L‐NPC and 4L‐FC, the proposed topology shows better self‐balancing performance and reduced control complexity. Simulation and experimental results verify the feasibility of the topology and method.