A fixed switching frequency sliding mode control for single-phase voltage source inverter

Maintaining good voltage regulation and achieving fast dynamic response under sudden load fluctuation are extremely important in distributed generation (DG) as well as uninterrupted power supply (UPS) systems. This paper presents a fixed frequency hysteresis controller, which is implemented on the basis of sliding mode control (SMC) technique and fixed frequency controlled logic with a hysteresis band. The controller retains the benefit of hysteretic current control having fast dynamic responses and mitigates the drawback of the variable switching frequency. Here a ellipsoidal switching surface for the inverter control is taken in phase plane, rather than the time-plot. The control scheme leads to a robust behavior against any load fluctuations. The designed switching surface allows a faster tracking of the externally given sinusoidal reference. The proposed method is then applied to 1-KVA, 110V, 50Hz islanded 1-Φ voltage source inverter (VSI) system. The results show that the dynamic response is quite faster.