Research On High Frequency Link Matrix Inverter And Parallel Operation

The high-frequency link three-phase matrix inverter consists of a high-frequency inverter, a high-frequency transformer, a matrix converter/cycloconverter and an output filter. The topological structure not only achieve the isolation of the circuit system and two-way flow of energy, but also overcome the large size, high cost, big noise and other shortcomings of the traditional inverter. It is a popular kind of topology in recent years study. The topology is gradually being applied to the new energy power generation and network systems, motor control and other fields. However, a single inverter can not meet the needs of the application in some high power applications. It needs multiple inverters in parallel operation to expand the capacity of the system. The study of inverter in parallel operation is earlier, and it is also relatively mature now. But most studies of parallel are only limited to ordinary inverters. The study of high-frequency link matrix inverter in parallel operation is less. It not only need large capacity, small size, light weight, low noise, and safety isolation to inverter system, but also claim the cost is not too high in some occasion. The high-frequency link matrix inverter in parallel operation meets the above requirements. So the study of high-frequency link three-phase matrix inverter in parallel operation that proposed in this article has far-reaching practical significance.Firstly, in this paper, it is made a corresponding summary of the research status of the high-frequency link matrix converter and the inverter in parallel operation. That made very good foreshadowing to the study of topic.Secondly, the article refers to the modulation strategy suitable for high-frequency link matrix inverter which called de-re-couple SPWM modulation strategy. With the voltage peak’s problem that produced when the topology is converting using the modulation strategy, de-re-couple SPWM modulation strategy is optimized to form integration SPWM modulation strategy. And the relationship between the mathematical model of high-frequency link three-phase matrix inverter and the mathematical model of general three-phase inverter is analyzed by the modulation strategy. The high frequency link three-phase matrix inverter is mathematical modeled follow the modeling method of general three-phase inverter. And the corresponding closed-loop control is designed.Thirdly, in this paper, the parallel operation of the high-frequency link three-phase matrix inverter is studied. The circulation is defined and the general circulation expression with the arbitrary inverter’s capacity ratio is deduced, and it provides convenience for the analysis of experiment. The droop-control equation used in this research is determined.The necessary and sufficient condition that realizes sharing load according to the capacity ratio of each inverter module is analyzed and summarized. And the robust droop-control method is applied to the parallel operation of the high-frequency link three-phase matrix inverter, that improving the defects of the traditional droop-control.Finally, the hardware and software circuit of the system are designed in this paper.The experimental platform of the high-frequency link three-phase matrix inverter parallel system is set up, that adopting digital control method of DSP and CPLD cascade. The correctness and feasibility of the theoretical analysis and simulation are verified by experiments.