The inverter, which is composed of IGBT’s (Insulated Gate Bipolar Transistor’s) and transformer, etc., is being applied for a wide range of home appliances, industry automations, etc. due to its high efficiency, high reliability, accurate speed control, and small size. The IGBT combines the advantages of s power MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) and a bipolar power transistor. As the power of an inverter increases, the higher the reliability and power density are required especially in a power module and gate driver design. In this paper, the electrical characteristics including the power losses for variations of inductance are studied through simulations by P-SIM.