Computer-Aided Electric Circuit Design of an Automotive Heated Window.

Abstract

In general, the electric circuits of automotive heated windows are designed on empirical knowledge and trial and error to satisfy the required power densities which substitute for the required window temperatures. In order to satisfy strict requirements and constraints in all cases, this paper presents a computer-aided design method of the electric circuits. The method devises an electric circuit model for the power density and a steady-state heat conduction model for the window temperature. The steady-state heat conduction of an element is calculated iteratively by the finite-difference method, considering heat transfers to six elements adjacent to the element. Width of filaments, thickness and width of bus bars, and kinds of paste (specific resistance) are revised iteratively until the required power density or the required window temperature is satisfied. The method was applied to a two-boxed passenger car and proved able to satisfy strict requirements.