Low-inductance snubber arrays for high-power, high-bandwidth switch-mode amplifiers

摘要

This paper presents a low inductance snubber design incorporating a damped DC bus capacitance and multiple RC+RCD cells arranged in two arrays. The design suppresses transient over-voltage peaks seen at the switching transitions in hard-switched, high-frequency switch-mode circuits which are created by an unavoidable interaction between circuit parasitic inductances, IGBT turn-off current slopes and free-wheeling diode reverse recovery currents. The array arrangement allows the use of small surface-mount, ultra-fast diodes by enforcing current sharing between many devices. An industrial application example is presented where the snubber design enables an increase in DC bus voltage from 200 V to 400 V when using 600 V Si IGBT's operated at a switching frequency of 75 kHz.Simulation results are presented and compared to experimental measurements to illustrate the operating principle and effectiveness of the array design.