Robust fractional order sliding mode control for solar based DC-AC inverter

Abstract

: Fractional order sliding mode control (FOSMC) strategy for a solar based DC-AC inverter is presented in this work. First FOSMC is implemented to voltage source inverter with a fixed DC input voltage of 400V to drive a load of 2.3 kW at a power factor of 0.8 lag. Here the load voltage and current through capacitor as state variables and a linear sliding surface are considered. FOSMC using Gao’s reaching law is derived for inverter circuit. FOSMC is implemented at load bus to control output voltage of inverter with linear and nonlinear loads to desired values. FOSMC controls the output voltage with good voltage regulation, less steady state error of 1.32 %, settling time of 0.15 ms, good dynamic response, and convergence to origin with less chattering compared to classical SMC. FOSMC based solar based VSI is presented. The maximum power from PV array is extracted using P&O MPPT algorithm. A boost converter is used to step up input voltage of 200 V to 400 V. P-V and I-V characteristics are obtained for a typical solar cell of 2.5 kW FOSMC requires less control efforts to obtain a pure sinusoidal output voltage waveform of 230 V (rms) with output voltage THD of 0.135% well within IEEE standards. PSCAD/EMTDC v4.6 is used for simulation work