New method for electrothermal simulations: HDTMOS in automotive applications

In this paper, an original method for electrothermal simulation is presented. This method is intended for automotive applications where an HDTMOS™-driven electronic actuator operates at a high switching frequency (20kHz). First, a SPICE electrical model of the switching cell is developed. The temperature-dependent intrinsic electrical parameters are extracted with thermally-controlled electrical I-V measurements. Power dissipation is calculated from the duty cycle, δ, load current, I_M, and the junction temperature T. The results, which are the power dissipation values for all combinations of (δ,I_M,T), are used to fill in a look-up table. Then the HDTMOS structure (chip, packaging and heatsink) is described with the help of the REBECA-3D software package, and the electrothermal balance is found for given waveforms of current and duty cycle. The originality of this method lies in the effective way of processing the great difference of thermal and electrical time-constants in the procedure of communication between the two simulation programs.