Improved Direct Power Control for Rectifier Based on Fuzzy Sliding Mode

An improved direct power control (DPC) is proposed for a three-phase voltage-source rectifier based on fuzzy sliding mode. It introduces the sliding mode controller (SMC) to enhance the disturbance rejection ability of the outer dc voltage loop. To ensure the stability of SMC, a fuzzy-based switching state controller is developed for the inner power loop, with which the switching states can be provided directly at the fixed time interval. This can contribute to the digitalization of controller and eliminate the drawbacks of the predefined switching table and the variable frequency that exists in the classical DPC. The effectiveness of the proposed DPC is verified by the simulation and experiment. Compared with the classical DPC, the current total harmonic distortion in the steady state is reduced by nearly half, and the transient setting time is shortened by at least 23%. The results indicate better performance of the proposed DPC in both the steady and transient states.