Laminated Bus Bar Design for Power Converter Circuit Considering Structural and Electrical Limitations

Abstract

In order to improve the reliability of a power converter circuit, it is important to analyze the DC-side stray inductance between the DC capacitor and the power devices because this may affect the switching losses, lead to the occurrence of over-voltages in power devices, and increase the short-circuit current. As such, a number of studies have investigated these effects through calculations, experiments, and circuit simulations. However, thus far, no paper has discussed a design of the stray inductance. In this paper, the authors propose a design procedure for the stray inductance of the laminated bus bar for a high-speed switching circuit using SiC power devices. The relationship among the bus bar inductance, the over-voltage, and the short-circuit current is clarified using an analytical MOSFET model. In order to verify the analysis results, an experiment using SiC-MOSFET and SiC-SBD rated at 1,200V is conducted. From these results, the upper and lower limitations of the bus bar inductance for the buck chopper circuit are found, and the design procedure for the wiring structure considering the stray inductance is discussed using the inductance map.