Model Predictive Current Control with Duty Ratio Optimization for Three Phase Grid Tie Micro Inverter Based on Runge Kutta Approximation

Abstract

In conventional model predictive current (MPCC) only one voltage vector is chosen and applied through one control cycle by using the discrete time system model. The selection of the voltage vector is based on minimizing a cost function. However, due to the restricted number of switching states which produced by three phase micro inverters, this will produce high current harmonics and limit the steady state performance. To enhance the effectiveness of the conventional MPCC, this research proposed an improved MPCC with duty ratio optimization for three phase grid tie micro inverter. The proposed strategy divides the one control period into two sub periods for two voltage vectors. This strategy uses the current error minimization principle to obtain the duration of the chosen voltage vectors. The simulation results prove the performance of the proposed MPCC in obtaining better steady state performance and reducing the total harmonic distortion of current to 0.77%.