Design and evaluation of automotive power module : 650V GaN E-HEMT with meandered interconnection and integrated motor-inverter power module
ABSTRACT
With increasing demand in automotive fuel efficiency and ever-strengthening global carbon dioxide emission regulations, electrification has become an indispensable trend. Especially in the automobile industry, miniaturization and performance are other major challenges, and they should be considered with electrification as goals in the equipment design stage. Because of the challenges, a tailored design and evaluation process is necessary for power modules that perform high-level power conversion for motor driving.
This dissertation attempts to present the design and evaluation of power modules used in electrified vehicles. The dissertation starts with the configuration of a power module and a description of each module component. A power module includes power devices and packaging components. Among the power devices, wide bandgap (WBG) devices have recently been widely used in power modules, and their characteristics are described. In addition, the roles of packaging components and their design considerations are presented. Because the power module treats electric power, electrical verification is important. Electrical verification methods based on the finite element method (FEM) and circuit simulation tools are introduced.
The aforementioned design and evaluation methods are applied to the proposed models of two applications. First, a new interconnection design is proposed. The interconnection is specially designed for the GaN E-mode High-electron-mobility Transistor (E-HEMT). The design process for the proposed interconnection is presented in detail, and a parametric study is conducted considering major design variables, to achieve minimum parasitic inductance and thermal resistance objectives. The expected advantages of the optimal interconnection design, as obtained from the parametric study, are described. To verify these expected advantages, various simulations and experiments are conducted. A prototype of the proposed interconnection is fabricated and experimentally evaluated. Secondly, the inverter power module is designed and analyzed to be applied in the motor-inverter integrated structure of the electric compressor and starter-generator components used in 48-V mild hybrid vehicle system. An improved power module design is proposed, and it demonstrates all of the electrical and thermal performances required in the integrated structure. The performances are evaluated by conducting electrical/thermal simulations and experiments. As a result, the superiority of the proposed interconnection for GaN E-HEMTs and the improved power module considering the integrated structure was demonstrated, and their evaluation processes were validated based on the similarity between the simulation and experimental results.
