This paper mainly focuses on ruggedness evaluation and design improvement of automotive power MOSFETs having a low voltage rating i.e. 50 V. The ruggedness of two types of power MOSFETs, i.e. planar and trench MOSFETs, have been investigated, simulated and compared under unclamped inductive switching (UIS) conditions by using industry-standard Technology Computer Aided Design (TCAD) tools. Additionally, the improvement to the ruggedness of the trench MOSFET due to gate corner smoothing is evaluated.