Control Method Research On Three-Phase Inverter Based On High Frequency Linked Matrix Converter

Matrix converter is a novel power converter, which bases on bidirectionalswitches. It permits frequency conversion in a single-stage processing without theneed of large-capacity energy storage components. It can obtain sinusoidal inputcurrent and unit power factor. Besides these, the output frequency and voltageamplitude can be regulated freely, and the energy can flow on bi-direction. It has greatresearching value and broad application prospect.The paper focus on the research of the inverter based on high frequency linkedmatrix converter, which adopted DC to three-phase AC. It utilized DC/HFAC/AC twostage power conversion to achieve inverter function and the former DC/HFAC usesingle-phase full-bridge inverter; with the isolated high frequency transformer, thelater circuit makes use of single-phase/three-phase matrix converter to carry outHFAC/AC function. This paper proposes a novel topology de-coupling controlmethod, and establishes the mathematical model of the matrix converter, proved thecorrectness of the de-coupling control. The paper research two modulate strategiesbased on this novel control method: conventional SPWM modulation strategy andSPWM hybrid modulate strategy, and analysis their principles and the working stateof main circuit, design logic circuit. Finally, by comparing the simulation studies,compared with the conventional SPWM modulation strategy, the SPWM hybridmodulation strategy can reduce the switch voltage stress and achieve adaptivecommutation by one step.Because of the complex circuit structure and contains many power devices, howto reduce the switching losses, and solve the voltage spike problem has become a hotresearch topic. The theoretical analysis and detailed logic circuit design of asoft-switching pulse density modulation strategy based on phase-shift control arestudied in this paper. The former inverter use a phase-shift control scheme, which canoutput periodic zero-voltage; and the later matrix converter using a control method,which combined of the traditional SPWM control ideas and pulse density modulationstrategy, to achieve matrix converter ZVS soft-switching, to solve the above problems.According to the edge before and after of the high-frequency voltage pulse, soften theconventional SPWM waveform and analysis the output voltage harmonic. Thecomposite rules and combined circuit of softening SPWM, and the control rules andlogic circuit of PDM modulation are describes in this paper. Finally, simulation model is built to verify the control by the Saber simulation software.On the basis of theoretical analysis, the paper carries out the experimentalresearch on the three-phase high frequency link matrix inverter, and built anexperimental prototype. The former circuit output duty cycle0.5square-wave voltageby using conventional inverter control method, the later matrix converter using theSPWM hybrid modulation strategy. The control core circuit of TMS320LF2812DSPoutput conventional SPWM waveform. Experimental results verify the theoreticalanalysis of the de-re-coupling control method and the feasibility of the SPWM hybridmodulation strategy.