A Developed Structure for DC-DC Quasi-Z-Source Converter with High Voltage Gain and High Reliability

In this paper, a developed structure for DC-DC quasi-Z-source (QZS) converters is proposed. First, the proposed two-stage structure is presented and analyzed. Then, the proposed structure is extended to n stages and its relations are calculated. Compared with other conventional structures, the proposed structure has higher voltage gain and higher reliability. The proposed topology is suitable for high power applications. To have the correct performance of conventional QZS converter, all impedance network elements must be intact. In the case of small failure in one of the elements, the operation of the whole system is disrupted. The proposed structure has high reliability because when one stage fails, the fault management system separates that stage from the other stages and the remaining stages continue to transmit power. In this paper, in addition to analyzing the operation of the proposed converter in different operating modes, calculations of voltage gain, voltage stresses across capacitors and reliability analysis are also presented. Reliability is calculated according to well-known Markov model. Moreover, a comprehensive comparison in terms of voltage gain and reliability is made between the proposed converter and the other conventional structures. Also, the rating values of inductors and capacitors are designed. Finally, experimental and simulation results are presented by using power system computer-aided design (PSCAD) software to verify the theories.