Novel Active Snubbers for SSCBs to Improve Switch Voltage Utilization Rate
Reza Kheirollahi, Shuyan Zhao, Hua Zhang, Fei Lu
Abstract
This article proposes two novel active snubbers for direct current (dc) solid-state circuit breakers (SSCBs): metal-oxide-varistor with resistor–capacitor-switch (MOV-RCS) and active-MOV with resistor–capacitor–diode (AMOV-RCD). In the snubber branch, either a half- or full-controlled switch can be applicable, leading to four novel topologies. There are two main contributions: 1) MOV is disconnected from the power line during SSCB OFF-state, which enhances reliability as neither voltage nor power appears on MOV and 2) voltage utilization rate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{v}$ </tex-math></inline-formula> of the main switch is remarkably increased, which improves efficiency and power density, and reduces design cost. Experiments of five prototypes are conducted including four proposed snubbers and a comparison with conventional MOV-RCD snubber. Results show that, for 1.2-kV MOSFETs as the main switch, new snubbers can enhance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _ {v}$ </tex-math></inline-formula> from 37.5% to 60%, achieving 183-A dc current interruption under 720-V dc bus voltage within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.4~\mu \text{s}$ </tex-math></inline-formula> . Meanwhile, the voltage peak is limited to 1.112 kV.