Static paralleling of power MOSFETs in thermal equilibrium

In automotive applications, sub-systems that used to be driven mechanically or hydraulically increasingly become electrically powered. The required inverters that feed such systems use parallel-connected power MOSFETs to switch hundreds of amperes. This paper investigates the static issues of paralleling MOSFETs, particularly the worst-case scenarios leading to the maximum temperature rise in the devices. A static electro-thermal MOSFET model is employed to describe current sharing and temperature rise for the general case of an arbitrary number of parallel devices. Analytical expressions are obtained to derive the worst-case conditions of the MOSFETs. Thus, designers can benefit from it to guarantee reliable circuit.