Research On Modulation And Basic Control Of Single-phase High-frequency Link Matrix Inverter

The high-frequency link matrix inverter is composed of an inverter in the former circuit,a high-frequency transformer,a matrix converter,an output filter and the load,which can realize the energy DC-HFAC-LFAC(HF:high frequency;LF:low frequency)transformation.Therefore,it has the advantages of compact circuit structure,bidirectional energy flow and no intermediate energy storage link,and the high-frequency link inverter has the light weight 、 small volume and low noise,for which the research on the high-frequency link matrix inverter has attracted widely attention.However,the key problem to the development of this kind of inverter is the safe commutation for the matrix converter.Therefore,this paper introduces the series resonant circuit in high-frequency link former circuit,and proposes a current-mode de-re-couple uni-polarity modulation strategy,which involves the series resonance.The method can avoid the interruption of the transformer secondary leakage current,while all the switches of the matrix converter can achieve zero current switching(ZCS),to accomplish the purpose of safe commutation.This paper selects the single-phase high-frequency link matrix inverter as the research object.First of all,aiming at the problem of safe commutation of matrix converter,it analyses the existing de-re-coupling SPWM modulation strategy and the de-re-coupling uni-polarity phase-shifted modulation strategy,and optimized the control logic for the de-re-coupling uni-polarity phase-shifted modulation strategy.Then,the working principle of the circuit and the mechanism of surge voltage are summarized.Secondly,for the possible reasons to cause the surge voltage in the existing modulation strategy,it introduces the series resonant circuit in high-frequency link circuit and proposes a current-mode de-re-coupling uni-polarity modulation strategy.Then,a detailed analysis of the working process of the modulation strategy for matrix converter commutation and zero current switching is given out.And from the angle of mathematical analysis and simulation,it is proved that the modulation strategy can effectively suppress the surge voltage.Thirdly,the research on the closed-loop control for the single-phase high-frequencylink matrix inverter is conducted.Based on the principle of current-mode de-re-coupling uni-polarity modulation strategy,the equivalent mathematical model of high frequency link inverter is established.On this basis,the voltage double closed loop control system is established,which based on quasi PR control and PI control.Then,the parameter optimization design method of PR regulator and PI regulator is analyzed in detail.Finally,after theoretical analysis and simulation research,the hardware and software of the system are designed in detail.It adopts DSP and CPLD to form the digital control circuit,and the experimental platform of the high frequency link matrix inverter is built,the experimental results show the feasibility and effectiveness of the proposed method.