Optimized Thermal Impedance Model of Thyristor Based on Heat Transfer Characteristics

This paper discusses the meanings, advantages and disadvantages of the Foster network and Cauer network models applied to the calculation of the junction temperature of thyristors in high-voltage direct current transmission converter valves. Aiming at the problem of simplifying the dynamic process of thermal diffusion in the traditional Cauer network, a piecewise lumped equivalent circuit thermal impedance model is proposed. Through the one-dimensional heat transfer equation, it is transformed according to the principle of difference. The difference equation is compared with the Cauer network to establish the connection between the heat transfer equation and the Cauer thermal network model. And solve the simplified Cauer network model to obtain the approximate solution of the heat transfer equation. The accuracy of the model has been effectively improved.