Modelling and designing the RC snubber circuit for a buck converter and testing its effectiveness

Abstract

The semiconductor power devices are the main core of all power electronic devices. Therefore, the protection of semiconductor devices and their operation at a safe level are required. Semiconductor power devices, resistors, and capacitors usually have parasitic inductances and capacitances. When a rapid switching transition occurs in the switching devices, it creates a noise, an electromagnetic interference and ringing, on the waveforms. These issues in power switching devices can be resolved by either replacing the switching device with another switch that has rated to exceed the stress or by using a series Resistor-Capacitor (RC) circuit to reduce the stresses to a safe level. The former solution increases the cost, while the snubber circuit, which is a simple RC circuit, is popular and is commonly used for any practical switching circuit, such as power converters, motor drivers, and power electronic devices. Although some works have been addressed in designing the RC snubber circuit, those studies are either based on simple work, or they involve very complex method with results that are often difficult to interpret. In this paper, therefore, we establish how to design an RC snubber circuit experimentally for a buck converter. The buck converter is modelled in PSpice software with and without the RC snubber circuit, where the comparison can be made. The model results show that the current across the switching device is reduced by the RC snubber circuit. In addition, the experimental results validate and verify the effectiveness of the RC circuit and eliminate the ringing and the noises.