Investigation of the Disturbance-Rejection Performance of a Modular Multilevel Converter Based on Active Disturbance Rejection Adaptive Fuzzy Sliding-Mode Control

With the widespread adoption of modular multilevel converters (MMCs) in high-precision control and disturbance-rejection applications, traditional sliding-mode control suffers from chattering and parameter uncertainty. To tackle the aforementioned issues, we propose a new composite controller-Active Disturbance Rejection Adaptive Fuzzy Sliding Mode Control (ADAFSMC), which is a combination of an integral sliding surface and an active-disturbance-rejection adaptive fuzzy logic concept. To make robustness even better, to minimize chattering even more, an integrator control law which contains a saturation type of sliding mode controller has been put within the adaptive procedure. The integral sliding surface eliminates the steady state error and the weight of the rules of fuzzy logic is updated online and adaptively and an Active disturbance rejection observer compensates for the disturbances. Simulation results show that compared with the traditional SMC, ADAFSMC can make the system achieve smaller overshoot, smaller steady state error, faster response and much better broadband disturbance attenuation in the frequency domain of the current and voltage tracking. We provide a feasible and effective design scheme of high performance ADAFSMC against high-order perturbation.