Variable Structure Back-Stepping Control of Two-stage Three Phase Grid Connected PV Inverter
This work presents a detailed analysis of a three phase grid tied photovoltaic inverter with variable structure back-stepping control approach. A nonlinear model of the system is derived and presented in rotational frame using the direct quadrature zero transformation (DQ). For the derivation of active and reactive power loops of the inverter, nonlinear back stepping approach is used. Moreover, sliding mode control method is used to derive the inner current loops while for the outer loop a virtual controller is derived using the Lyapunov function. The control loops are implemented in MATLAB/Simulink environment. To test the controller performance, active power variation, DC link voltage variation and reactive power variations are inflicted. The obtained results under the proposed control scheme are compared with boundary layer design based sliding mode controller. From the comparative analysis it is concluded that the proposed controller exhibit superior and robust performance under all test conditions.