###### Abstract
Two corresponding models were established using FEM and thermal network, and thermal characteristics of the permanent magnet linear motor under continuous, short-term, and intermittent operating conditions was obtained. The results obtained by the two methods were compared and analyzed through experiments. The impact of the water-cooling system on the overall temperature rise distribution of the linear motor was investigated. [PERSON] et al. [6] developed a plate moving-magnet LG for an opposed piston FPEG. To prevent demagnetization from causing unstable operation of the LG, a CFD model was established using FEM and the temperature field was analyzed. It was found that the air-cooling condition was enough to meet the heat dissipation requirement under long-term stable operation. [PERSON] et al. [24] proposed a simplified fluid model separated from the coupled calculation of a permanent magnet linear motor. Interpolation and polynomial fitting were used to compute the average velocity of the surfaces. Steady-state temperature distribution characteristics were then calculated by a coupled model. The simplified fluid model greatly reduced the computational time of the electromagnetic-fluid-thermal coupling simulation without sacrificing computational accuracy. [PERSON] et al. [22] investigated the temperature rise characteristics of a coreless permanent magnet synchronous linear motor under different conditions, using thermal-fluid-solid coupling FEM and thermal network analysis as the modeling methods. A water-cooled structure suitable for a coreless double-layer permanent magnet synchronous linear motor was designed and the heat dissipation effects of different topologies were compared and analyzed. Then, a response surface model was developed to obtain maximum sustainable current and electromagnetic performance. According to the literature, the study of the LG temperature field is increasingly receiving attention from scholars, and various simulation and experimental methods are being tried to estimate the temperature field. Reasonable distribution of the LG temperature field can ensure its safe and reliable operation and service life. LGs have multi-physics field coupling characteristics, and relationships of electromagnetism, heat, and fluid are quite complex [25,26]. The accuracy of electromagnetic loss calculation has a significant influence on the temperature rise calculation. However, the influence of temperature rise on the material performance of the motor is ignored in one-way coupled simulation, which inevitably leads to differences between the calculated results and the actual values. During the actual operation of the electric machine, the electromagnetic field and temperature field are coupled and affect each other. Therefore, it is necessary to study and analyze the bidirectional coupling of electromagnetic and thermal fields considering the influence of temperature on material properties to obtain more accurate temperature field distribution. Thus, electromagnetic-thermal characteristics could be understood more thoroughly, allowing better cooling to be provided for LGs [27], ensuring stable operation at appropriate operating temperatures. In this paper, an electromagnetic-thermal bidirectional coupling was adopted to calculate the temperature field distribution of the TPMLG. The structure of the FPEG system was introduced and the main parameters of the TPMLG prototype analyzed were provided. Furthermore, a two-dimensional electromagnetic field and three-dimensional temperature field coupling model was erected to analyze thermal characteristics under different air-cooling conditions. Then, the temperature field of the TPMLG was investigated. Consequently, change patterns of the steady temperature field with loss and air flow velocity were analyzed. This study could provide some reference for material selection and support for cooling design of LGs.