A Quasi-Interleaved DC-DC Converter with High Voltage Gain Based on the Z-Source Structure

In this paper, a new high voltage gain DC-DC converter is proposed. The method of connecting the Z-source network to the primary side of an interleaved step-up converter achieves the advantages of both Z-source and interleaved converters, and realizes their benefits. Using the pulse width modulation (PWM) technique to control the output, zero voltage switching (ZVS) conditions at turn on times are provided for the active semiconductors and zero current switching (ZCS) conditions at the turn off times of the diodes are provided in the converter. The realization of the soft switching conditions for all power switches and diodes in the converter has reduced EMI noise and switching losses and thus increased the converter efficiency. Therefore, it is possible to design the converter to operate at high frequencies, if the appropriate devices are available, in order to reduce the size and volume of passive components of the converter, including inductors, capacitors, and filters required to increase the power density. In addition, soft switching operation helps to increase their useful life by reducing voltage and current stresses of the components. To verify the proposed converter performance, a laboratory sample of it is also designed and implemented and experimental results are given under different conditions, in addition to simulation and mathematical analysis. Here, despite changes in input voltage of 40-50 V and output power of 200-400 W, the output voltage value of 400 V is well regulated, by properly controlling the pulse width at the switching frequency of 100 kHz. In addition, maximum efficiency value of this converter is 96% in simulation results and 92.5% in the given experimental results. Considering that, the EMI noise and switching losses are effectively reduced in this converter; low conduction loss components can be used, if necessary to increase the converter efficiency, practically.