A Quadratic Quasi-Z-Source Full-Bridge Isolated DC-DC Converter With High Reliability for Wide Input Applications

In this article, two configurations of the quadratic quasi-Z-source (Q-qZS) isolated dc-dc converters are presented, namely continuous input current and discontinuous input current configurations. The operating principles and steady state of the continuous input current topology analyzed in this article is characterized with the following features: 1) wider operating range due to buck and boost functions in a single stage; 2) draws continuous input current; 3) low input current ripple compared with other qZS-based isolated dc-dc converters; 4) better reliability and good immunity against EMI noise; 5) common ground between the input source and the inverting bridge; and 6) continuous control over the entire operating range. Compared with other qZS-based isolated dc-dc converters, lower current stresses on active and passive components used are realized. Hence, the total magnetic volume/energy required by the proposed converter is reduced with the potential of achieving high power density. A prototype of 40-140 V input voltage, 300 V output, and 550 W rated power is developed to validate the performance of the proposed converter presented.