Design of a Controller for Three Phase Four Leg Matrix Converter /

Abstract

Matrix converter is the direct AC-AC power conversion technique. There are two types of matrix converters, direct matrix converter having no storage elements or DC components and indirect matrix converter having stages and DC link components. To design a controller for direct matrix converter is the main concern of my research work here. For the classification upon working there are two types of matrix converters 3-Phase 3-leg matrix converters and 3–phase 4-leg matrix converter. 3-Phase 4-leg matrix converter has 4th leg as a path for the flow of zero sequence current in the case when it feeds un-balance load. Here as the main topic of concentration is 3-Phase 4-leg matrix converter. The control of 3-Phase 4-leg matrix converter is different and complicated as compared to the controller design for 3-phase 3-leg matrix converter. In case of 3-Phase matrix converter system there are different control techniques previously used among which are various types of repetitive controllers, model predictive controllers and sliding mode controllers. In this work a proportional resonant controller is used for the control of 3-Phase 4-leg matrix converter system considering the un-balance load. The main advantage of this controller as compared to other controller is selection harmonic control as well as to satisfy the required delay margin. The loop to be tracked is considered the output voltage loop as the main controllable entity as compared to inner current loop to guarantee the desired stability in the amplitude and frequency to feed the sensitive un-balance load. As in these types of applications the inner current is not considered due to faster rate and bandwidth limitation. The system is consisting of a matrix converter, an output filter and un-balance load for this purpose. The general scenario for the designing of a controller for any system is based on the worst condition that a system can face so that practical response of controller is enough strong to reject all the unwanted changes in the system. The software to be considered for this simulation is Matlab Simulink. On the basis of Bode diagrams and reference voltage tracking the system performance fulfills the stability criterion which shows the correctness of simulation.