Electromagnetic-thermal-fluid coupled modeling and temperature analysis of a linear generator for linear range extenders

When the linear generator (LG) is used in linear range extender (LRE) systems, heat dissipation becomes a significant challenge due to limited installation space and poor working conditions. This paper proposes a coupled modeling method to analyze the thermal characteristics of the LG while considering the actual operating conditions of the LRE. An electromagnetic-thermal-fluid coupled model is developed to study the temperature distribution and heat transfer pathways of LRE under various operating conditions. Furthermore, the effects of different cooling strategies on cooling performance are evaluated. Results indicate that as the current increases, the temperature rises more rapidly, resulting in a higher steady-state temperature. During the cold start process, the temperatures of all components remain below their material limits. During the power generation process, natural cooling is insufficient to control the temperature rise, while air cooling can significantly reduce the overall temperature. The winding reaches the highest temperature, followed by the stator, cooling shell, and mover. The temperature distribution shows a gradient that decreases from the high-temperature areas at both ends towards the center, reflecting the heat transfer path from the piston to connecting rod, mover, and stator. Under water cooling conditions, the maximum temperature of the LG is reduced to only 37.3 °C. The windings, stator, and cooling shell display a temperature pattern with higher temperatures on the left and lower temperatures on the right. The mover exhibits a symmetrical temperature gradient that increases from the center to both ends. The cooling shell area closest to the cooling pipe has the lowest temperature.