The control for a five-level grid-connected inverter based on passive sliding mode

In order to improve the grid connection control performance of the inverter under non-ideal operating conditions, the control strategy of single-phase five-level inverter with coupled inductors is investigated. Firstly, the five-level generation mechanism of the inverter is analyzed and its mathematical model is established; secondly, to address the problems of slow dynamic response and poor quality of grid-connected current for non-ideal conditions that exist in traditional control, a passive sliding mode (PBC + SMC) control strategy based on the combination of passive control (PBC) and sliding mode control (SMC) is proposed, which the output of the sliding mode controller is used as the input of the passive controller; finally, a passive sliding mode control simulation system for a five-level grid-connected inverter is built on the simulation platform, and a variety of different operating conditions are simulated. By comparing the simulation and experimental results of three control strategies: passive sliding mode control (PBC + SMC), passive control (PBC), and proportional–integral control (PI), the proposed passive sliding mode control strategy has good steady-state and dynamic performance, with faster response, lower harmonic content, and better robustness than the other two control strategies.