Nonisolated Ultra-High Step-Up Quadratic Converter With ZVS Operation and Low Switch Voltage Stress

This article proposes a nonisolated quadratic converter with ultra-high voltage conversion ratio. In the presented structure, an auxiliary circuit containing coupled inductors (CIs) and a voltage multiplier cell is integrated with the quadratic converter to obtain higher voltage gain. As a result, voltage stress over switches is reduced significantly and
mosfet
s with low
on
-resistance can be used to lower the conduction losses. In addition, soft switching performance is achieved by the auxiliary circuit and all switches are turned
on
and turned
off
under zero voltage conditions to eliminate the switching and capacitive turn-
on
losses. Furthermore, the soft switching is load independent and is performed over the entire load variation. Moreover, due to leakage inductances of the CIs, the reverse recovery problem of the output diodes is alleviated. Due to the abovementioned advantages, the converter efficiency is enhanced notably. Also, the converter benefits from continuous input current and common ground between the input and output, which removes any limitation on the converter applications. In this article, the converter operation is investigated comprehensively and in order to validate the theoretical analysis, the experimental results of a 150 W prototype are provided.