Thermal Analyses of Reactor under High-Power and High-Frequency Square Wave Voltage Based on Improved Thermal Network Model

In order to quickly calculate the stable temperature of a reactor driven by high-frequency and high-power pulse voltage, an improved thermal network model suitable for a reactor under this condition is established in this paper. In power electronic equipment, the maximum temperature of the reactor is usually concentrated in its internal core. Moreover, with the increasing demand of high-power density in power electronic devices, the structure design of the reactor is more compact, and the internal magnetic field will affect the accuracy of the temperature-measuring device. Therefore, it is difficult to measure the internal temperature rise of the reactor directly. However, its stable operating temperature could be analyzed by the thermal network modeling methods and heat transfer analysis tool. Therefore, a convenient and accurate thermal network model of the reactor under high-frequency and high-power square wave voltage is established by considering the equivalent thermal resistance of the winding, the three-dimensional geometrical effect of the core and the effect of the high-frequency repeated pulse stress on the thermal penetration depth. Additionally, the internal temperature of the reactor can be obtained through the external temperature in terms of the presented model. To verify the feasibility of the thermal network model, the corresponding multiphysical field finite element simulation and the reactor temperature measurement platform is built. The simulation and experimental results show that the proposed thermal network model has a high precision and fast calculation speed, and it is an effective tool for thermal analysis of the reactor.