Performance evaluation of passive voltage snubbers to attenuate the effects of leakage inductance In a Quasi-Y-Source DC-DC converter

The use of renewable energy sources, especially photovoltaic, generated the need to develop new power converters with the ability to operate in a wide range of voltages with higher levels of flexibility, efficiency, and voltage gain. In this scenario, the converters based on impedance source networks of Quasi-Y (QSY) type, satisfy these requirements, having the feature of continuous input current, suitable for use in applications involving renewable energy sources. However, converters based on impedance source networks with magnetic coupling as a QSY type, have the inherent characteristic of producing large voltage efforts across the power switches during the converter operation, due to the existence of leakage inductance in the coupled inductors. Hence, the development of dampening circuits, such as passive voltage snubbers, is essential to allow the safe operation and protection of the power switch. This paper presents the study of three different types of passive voltage-dampening snubbers (RC, RCD, and LCD) applied in a QSY DC-DC converter, to attenuate the unwanted effects of leakage inductance. The design methods of the damping circuits applied to the QSY DC-DC converter are presented and the evaluation of the operation is carried out through computer simulations. The proposed design equations for the RCD and LCD snubbers proved to be effective through the simulation results, demonstrating their effectiveness. Among the three damping circuits evaluated, the LCD type showed better results, reducing the voltage stress across the power switch by 30% and increasing the efficiency of the converter, these results are promising and may allow the use of QSY converters in renewable energy applications.