| With the rapid development of power electronic technology, it is closely related to every field of industrial manufacture and our social activities. The voltage source inverter is being widely used in different occasions of UPS, motor speed-governing system and renewable energy generation as the most mature of traditional power converter. But it also exists some drawbacks due to the limitation of the structure, 1) upper and lower tubes are able to produce shoot-through state easily result from EMI which would hurt the circuit. 2) the scope of traditional voltage source inverter applications is greatly limited because of its buck topology, which the AC output voltage cannot exceed the dc link voltage. Z-source inverter and the corresponding derived topology can effectively overcome disadvantages of traditional power converter and have wide application prospects, which can achieve buck-boost function with the shoot-through state.A new single-stage inverter is proposed in this dissertation, which is referred to soft-switching trans-Z-source inverter with active clamp(SSTZSI), through the analysis of tans Z-source inverter. Compared to existing topologies, the new converter has some merits, such as good reliability, high voltage ratio and efficiency.SSTZSI allows the shoot-through state possible comparing with the traditional topologies, which can greatly enhanced the reliability of the circuit. Avoiding one-to-one correspondence between shoot-through duty ratio and output voltage gain of Z-source inverter, SSTZSI alleviate the contradiction between modulation factor and duty ratio by utilizing the coupled inductor to adjust the DC link voltage in the aspect of boost principle. Through adding active clamp circuit, which is used to eliminate the voltage spike that is induced by the trapped energy of the leakage inductor, both the main and auxiliary switches can be turned on with ZVS condition that results in high efficiency of SSTZSI.The specific operating mode and mechanism of SSTZSI is analyzed and the relationship of energy conversion between the parts of the circuit is described in detail, on the base of which, the effects of parasitic parameter and boost factor on the circuit performance is expressed, which gives the theoretical basis for practical design. The DC link voltage and three-phase ac output voltage are stability controlled by closed loop control system, which is designed according to the building of small-signal model. Experimental results of 1kw inverter are given for hardware verification, which agrees well with the theoretical analysis and simulation results. |
