This paper presents the results from a parametric simulation study that was conducted to optimize the design of a high-current 4.5 kV half-bridge Si-IGBT/SiC-JBS hybrid module for medium voltage hard-switched power conversion as well as to compare the performance of the hybrid module to the all-Si configuration. The simulations are performed for a circuit that emulates hard-switched conditions similar to a full wave inverter and utilizes validated electro-thermal models for the 4.5 kV Si IGBT, Si PiN diode, and SiC JBS diode and a validated thermal model for the module package. Simulations for various circuit and module parameters including the size and number of SiC JBS diode chips, gate resistances and switching frequencies are used to design the module to be used for demonstration in a Naval power converter application.