Event

Announcement: Ph.D. Dissertation Defense

 

Name: Ayodhya Gamwari

Committee:
Prof. Alireza Khaligh (Chair)
Prof. Xin Zan
Prof. Sahil Shah

Prof. Behtash Babadi
Prof. Damena Agonafer (Dean's Representative)

Date/time: July 23, 2026 / 2.00 PM 

Location: AVW 1146

Title: A LOW-INDUCTANCE SIC BARE-DIE HALF-BRIDGE POWER MODULE FOR TRACTION INVERTER APPLICATIONS

Abstract: 

Conventional traction inverters employ packaged power devices such as the TO-247, which introduce wire-bond lead inductance, high junction-to-case thermal resistance, and a large package footprint that constrains PCB layout and increases commutation-loop inductance. These limitations result in increased voltage overshoot, higher switching losses, and reduced operational reliability. Achieving next-generation high-power-density traction inverters therefore requires a holistic electro-thermal design approach that minimizes parasitic inductance while providing effective thermal management. 

 

This dissertation presents the design, modeling, fabrication, and experimental validation of a modular bare-die SiC half-bridge power module that addresses these challenges through integrated electro-thermal design. A modular ultra-low-parasitic bare-die SiC half-bridge architecture is developed in which additively manufactured, liquid-cooled multifunctional components simultaneously provide electrical interconnection and thermal conduction paths. This architecture enables scalable implementation across multiple traction inverter topologies. To support the electrical design of the proposed architecture, analytical switching-transition models are established to estimate switching power loss, predict crosstalk-induced spurious turn-on, and determine the required high-frequency decoupling capacitor sizing. To enable practical realization of the proposed architecture, a repeatable assembly methodology is developed to overcome coefficient-of-thermal-expansion (CTE) mismatch and high-voltage insulation challenges. The developed phase-leg module is integrated into a two-level, three-phase voltage-source inverter, whose DC-link capacitor bank is further modeled to optimize inverter volume.

The power-loop inductance of the developed module is estimated using finite element analysis (FEA) to be 1.48 nH. The analytical switching models are validated through double-pulse testing (DPT), achieving a mean crosstalk prediction error of 3.6 %. The thermal resistance of the liquid-cooled heatsink path is measured to be 0.8 K/W. The complete inverter is experimentally validated up to 18 kVA per phase, corresponding to a 54 kW three-phase system, with single-phase operation imposing more severe DC-link ripple than balanced three-phase conditions. This operation corresponds to a peak power density of 93 kW/L.

The modular phase-leg architecture presented in this dissertation provides a scalable foundation for future high-power SiC traction inverter platforms. The proposed electro-thermal design methodology establishes practical guidelines for simultaneously optimizing electrical packaging, thermal management, manufacturability, and DC-link integration, thereby providing a foundation for next-generation high-power-density automotive traction inverters.