Equivalent Electrical Model and Software Tool for SPICE-Compatible Thermal Simulations of High-Power Resistors

Optimized design of high-power braking resistors for traction applications is a complex task. The value of the power dissipated can be very high (up to the order of megawatts) and normally pulsating. In addition, these resistors should stay in predefined, usually small areas on the train, which makes them have to meet some tough specifications: minimum weight, high resistance to vibration, and high reliability and durability. Since it is necessary to anticipate and establish the distribution and evolution of the temperatures reached in different internal areas, it would be necessary to develop a complete numerical simulation using a software tool based on computational fluid dynamics (CFD) for each design, which implies a very high-computational cost. In this paper, a new equivalent electrical circuit is proposed to model the thermal behavior of this kind of resistors. The electrical equivalent circuit parameters are obtained by a newly developed software tool that collects results and trends obtained from a large number of previous CFD simulations. After that, SPICE can be employed to obtain thermal simulations and predict temperature evolutions.