Model Adaptive Controller for Multi-Level Quasi Z-Source Inverter

Abstract

The Model Reference Adaptive Controller (MRAC) is implemented for the model of nine- level Cascaded H Bridge (CHB) asymmetrical Quasi Z Source Inverter (QZSI). The proposed MRAC controller forces the output current to be sinusoidal, with low current harmonics, and to be in phase with the line voltage. The advantages of using MRAC over conventional proportional-integral control are its flexibility, adaptability, and robustness; moreover, MRAC can self-tune the controller gains to assure system stability. Since the QZSI is a non linear system, it is hard to design the controller. MRAC is simple and predict the future values of output variables using a dynamic model of the process comparing conventional PI controller. In this work, the performance of MRAC is compared with conventional PI controller based on the settling time and harmonic distortion. The simulation results clearly showed that the MRAC can lead to reduction in the settling time and harmonic distortion of the obtained output for the system. In addition to this the cascaded nine level QZSI with asymmetrical input voltage in the ratio of 1:3, whose performance is analyzed to provide a boosted output voltage and due to the asymmetrical input configuration the output voltage can be obtained with more voltage levels with lesser number of component thus lead to better outputvoltage quality with the reduction in filter size.