Abstract: A novel dynamic sliding mode control (DSMC) strategy for direct-driven PMSG system was proposed to improve wind energy generation efficiency in overall-wind-speed operating condition. Based on the multi-stage working characteristics, optimum torque control method was adopted to implement the MPPT task when wind speed was under the rating value, and power control method was adopted to implement the constant power generation task when wind speed was above the rating value. The controller was designed by the sliding mode reaching law method of power exponent function. Due to the switch function amplitude feedback, the switch gain was granted the capability of automatic adjust with tracking error. The tracking response time was shorten while the overshoot was effectively suppressed. The DSMC law involved a first-order integral process of the control input signal, which could make the actual PMSG control current continuously and smoothly. The integral process contributed greatly to weaken chattering. Simulation results demonstrate the effectiveness of the proposed DSMC strategy.

Key words: wind energy generation systems, permanent magnet synchronous generator, maximum power point tracking, power control, dynamic sliding mode control