Comparative Implementation of a two-stage DC-Link

Abstract:
This paper gives an approach and experiment to reduce voltage overshoots on hard switched semiconductors. Since the main reason for high-frequency oscillations is stray inductance in the commutation loop and components, a second stage, high-frequency capacitor is mounted to block high frequencies from the DC link. A remote DC link capacitor is used to provide sufficient capacitance. Different types of capacitors, values of capacitance and count of units are equipped close to the semiconductor and the voltage is measured at the low-side switch and DC connection. The effects of a single large capacitor and several small capacitors are evaluated. The plots are shown and compared against each other.