Indirect Matrix Converter Control Strategy

Indirect matrix converter, as a new topology converter, has high-quality input current waveform and output voltage waveform, high power factor characteristics. Therefore, it is not only the little harmonic pollution, but also for high-performance speed of induction motor drive. Based on the indirect matrix converter prototype which based on IGBT, this paper has completed the study on its control strategies combining with simulation.This paper has carried out the study on the control strategies of indirect matrix converter. At present, two-part PWM modulation strategy and space vector modulation (Space vector modulation, SVM) strategy are used generally. The Matlab/Simulink model of motor system drived by the indirect matrix converter was established in this paper, and the simulation of two modulation strategies was complished. The simulation results are analyzed also, including the harmonics of input current and the output current, the output torque and speed, and so on. It was shown from the harmonic that indirect matrix converter had good performance and was superiored to matrix converter obviously.The paper analyzed the commutation method of the indirect matrix converter. According to the topology features of the indirect matrix converter, the traditional four-step commutation method based on the current direction was slected in rectifier and the dead commutation was slected in inverter. Through set properly of the step time of four-step commutation and the dead time of dead zone, safe commutation between IGBTs has been complished and output waveform quality and voltage transfer ratio have been improved.In the process of the rectifier experiments debugging, for the issue of intermediate DC link voltage appearing negative randomly, anti-interference synchronous trigger mode was proposed based on traditional synchronization trigger mode. Through the successful application of the synchronous triggering mode, the problem of the random negative DC-link has been solved.In this paper, the study on control strategies has been finished on the experimental platform of the indirect matrix converter based on DSP+CPLD. Space vector modulation has the controller DSP TMS320F2812, and four-step commutation and the dead commutation has been relized by CPLD EPM9320A. Experimental studies include the two modulation strategies rectifier experiments, space vector PWM inverter experiments and experiments both rectifier and inverter. In the experiments both rectifier and inverter, considering the advantages and disadvantages of the two modulation strategies, two-stage PWM modulation strategy had been used finaly. Now some preliminary results have finished, and the prototype can operate safely.