Sliding Mode Variable Structure Control For Matrix Converter Fed Permanent Magnet Synchronous Motor Drive System Based On Perturbation Model

Matrix Converter (MC) is an AC-AC conversion device without dc-link energy storage elements. It has some very attractive advantage and is suitable for permanent magnet synchronous motor drive, such as energy regeneration, sinusoid input currents with low THD, no need of DC-link energy storage elments and unity power factor. However, disturbances of the input voltages will be immediately reflected to the output voltages as the absence of dc-link energy storage elements in a MC fed PMSM drive(MC-PMSM). Line voltage source unbalances is one of typical disturbances in power grid. It causes harmonics in input currents of MC, and deteriorates performance of torque and speed of MC-PMSM. Another disturbance for output of MC-PMSM is parameters perturbation. It affects torque and speed of PMSM by deteriorating control performance of current loop in the vector control.In this paper, a sliding mode variable structure current control (SMC) strategy is used in current controller design for MC-PMSM drive to improve roboustness to input voltage disturbance and parameters perturbations to replace the PI controllers, combined with forward compensation. Sturcture and cost of the system is simplified and reduced.The principles and implementation of the vector control of PMSM drive system are firstly presented. Then, the space vector modulation of MC is introduced. The effects of grid disturbances on output of matrix converter (MC) are discussed and analyzed. The decoupled model of PMSM is given in which perturbation of input voltage and parameters of motor is considered. Based on the model, an SMC current controller is designed by using integral sliding mode surface and exponential approach law. Digital simulation has been done to verify the performance of the proposed strategy. As can be seen from the results, input voltage disturbance and parameters perturbation have slight effect on current control by using SMC.Finally, an experimental setup is built based on the theoretical analysis and simulation to implement the proposed SMC strategy for MC-PMSM drive. The results show that the effect of input voltage disturbance and parameters perturbation is significantly reduced. The second order harmonic in stator currents of PMSM produced by input voltage unbalance, which always causes perturbation on torque and speed of motor, is cosequently decreased. The SMC strategy for MC-PMSM proposed here is proved to be implemental by the experimental results, and the research of this paper is valuable for the practical application in industry of MC-PMSM.