A unipolar fixed hysteresis band based sliding mode control of single phase grid connected LCL filtered voltage source inverter

This paper describes a Sliding mode control (SMC) technique for a single - phase grid connected voltage source inverter (VSI) through LCL filter for distributed generation applications. SMC technique is applied as a control method with a fixed band hysteresis controller. Mathematical modeling of the VSI circuit is done through state space analysis. This control method provides robust current voltage regulations under load and line parameter variations and achieve unity power factor. Both two level and three level switching algorithms are implemented with SMC. It has been found that the use of three level switching algorithms with SMC gives good grid current response with less total harmonic distortion (THD) in a VSI connected to the grid. Stability of system is obtained through frequency response analysis. Simulation results are presented to demonstrate the effectiveness of controller. PSCAD/EMTDC version 4.2 is used for simulation studies.