Research On AC-DC Matrix Converter Close-Loop Control Strategy For Automotives

The technology of matrix converter has many advantages compared with traditional AC-DC-AC power converter, such as: the topology of circuit is simple and small; there is no big capacitor as energy storage during the energy conversion; it has single stage energy conversion, large power transmission density and bidirectional energy transmission; adjustable input power factor can be any value between 1 and -1; it step-down power conversion and very low pollution on the grid. Since matrix converter has so many unique advantages, it will definitedly obtain rapid development in the field of power conversion in future.This paper gives a brief introduction to the background at first, and then states the history of matrix converter and the research status at home and abroad in detail, makes an explanation about the importance and urgency of developing the technology of matrix converter. Finally,it describes the main work of this paper.The main content of this paper is as follows:Firstly, this thesis presents the mathematical model of 3 to 3 phase matrix converter based on its circuit topology, and based on this, deduces the circuit topology and mathematical model of AC-DC matrix converter. With respect to its mathematical model, this paper proposes two kinds of modulation strategy: optimized AV algorithm and indirect space vector modulation algorithm. The work of the two modulation algorithm is described under the AC-DC matrix converter. The advantage and disadvantage of the two algorithm are compared and summerized. Then the indirect space vector modulation algorithm used for closed-loop control is obtained.Secondly, the commutation strategy of matrix converter technique is analyzed and discussed in detail, and four-step commutation mode is decided to be used for safe commutation strategy, and logic circuit is designed to achieve the four-step commutation strategy. The four-step commutation mode is simulated in QuartusII and the results verify the correctness of the principle of four-step commutation.Thirdly, this paper makes a simulation analysis of the two control strategy of AC-DC matrix converter, and builts the system model in Matlab/Simulink, and verifies the correctness of the proposed control strategy. In addition, according to the derived indirect space vector modulation algorithm, this paper brings up a closed-loop control strategy in control of the modulation ratio m.At last, this thesis builts the experimental platform of AC-DC matrix converter system, describes the selected experimental hardware, and designs the software of the system. It also experimentally verifies the proposed closed-loop control strategy. In the experiment, the system achieves the experimental objectives, such as the unit input power factor and single stage buck energy conversion. The result lays foundation for further study.