Constrcuction Study Of Impedance-source Network-based DC-DC Converters

The power electronic converters play a critical role in the power conversion system. Therefore, the study of novel high-performance power electronic converters is a hot topic in the filed of power electronics. The impedance-source network-based power converters(e.g. the Z-source converters) which are gain a lot of attentions since they proposed in 2002. The impedance-source networks have the advantgage of simple structure. The converters based on the impedance-source networks can reduce the number of power conversion stages in the system power chain, which may improve the performance of the power system. However, the research of the impedance-source network-based converters in nowadays is manily in the aspect of DC-AC converters but only a few in the DC-DC converters. Furthermore, there has no systematic method of topology construction of the impedance-source network-based DC-DC converters.According to the above problems, firstly, this paper has summarized the topological characteristics of the existing impedance-source network-based converters, and it is found that a series of impedance-source network-based converters with different performances can be constructed by shifting the connection-way between the impedance-source network and the power source. Then, four basic impedance-source networks are designed based on a LDC circuit unit which is formed by connecting an inductor, a diode and a capacitor in series. Finally, a topology constrction method of impedance-source network-based DC-DC converters is proposed by shitfing the connection-way between the impedance-source network and the power source. And a series of high-gain DC-DC converters are derived.The main work of this paper includes following fields:1. The connection-way between the impedance-source network and the power source is summarized from the existing impedance-source network-based converters,including the source is in the branch of diode of the impedance-source network, the source is in the branch of inductor of the impedance-source network and the source is series with the impedance-source network.2. A LDC circuit unit which is formed by connecting an inductor, a diode and a capacitor in series is proposed. Then, four basic impedance-source networks, i.e. the quasi-Z-source, the common-anode-quaradic, the common-cathode-quaradic and the switched-inductor impedance-source networks are deduced based on the LDC circuit unit. And the operating characteristics of these four impedance-source networks are illustrated in briefly.3. Based on the four impedance-source networks and by shitfing the connection-way between the impedance-source network and the power source, a topology construction method of impedance-source network-based converters is proposed. And a series of high-gain DC-DC converters are obtained,including single impedance-source network-based DC-DC converters and compound impedance-source network-based DC-DC converters.4. Using the quasi-Z-source DC-DC converter and the switched-inductor quasi-Z-source DC-DC converter as examples respactively. Then, the operating analysis, parameter design, simulation and experimental verification of the two DC-DC converters are presented to verify the feasibility of the proposed topology construction method of impedance-source network-based DC-DC converters.