Design of a Repetitive Controller for Matrix Converter

Abstract

Matrix converters are an area of interest for industry nowadays as they provide AC-AC power conversion directly with desired variable frequency and magnitude without any intermediate DC-link. It is also regarded as an all silicon solution because it uses bi-directional switches array for the purpose of conversion and no energy storage links are used. High quality waveforms can be generated with minimum losses just by executing the commutation of bidirectional switches in the right way. Matrix Converters can be used in many applications such as variable frequency applications, aircraft power supply applications, induction motors, uninterrupted power supplies etc. Many control structures have been proposed for Matrix Converter systems such as sliding mode control, dead beat control and selective harmonic control in order to improve systems performance. Since, Matrix Converter has a high switching frequency thus distortion and periodic errors will exist in the output voltage waveform, which creates a necessity to remove such unwanted periodic errors. Repetitive control structure is most suitable for removal of periodic errors. In this work, a repetitive controller for Matrix Converter is proposed. Main objective of a repetitive control structure is to track a periodic signal in stable closed loop by generating an extraordinary gain at periodic signal’s fundamental frequency and its multiples. Applications of repetitive controllers include PWM rectifiers/inverters, disk drive systems and robotic manipulators. Repetitive controller proves to have a good steady state performance but it is weak when its transient performance is considered, and that is why repetitive controller is equipped with a linear controller to ensure better performance in different conditions. Results of MATLAB simulation studies show that the repetitive controller proposed in this study is stable and provides exact tracking of the reference signal by the output voltage signal.