基于多热流路径热网络模型的压接型IGBT在线结温估计方法

Online junction temperature (Tj) estimation of press-pack insulated gate bipolar transistors (PP IGBTs) plays an important role in the reliability assessment of flexible direct current converter valves. Due to the bidirectional heat transfer characteristic of PP IGBTs, traditional thermal network models are difficult to use to estimate Tj of PP IGBTs. An online junction temperature estimation method based on the thermal network model with multiple heat flow paths is proposed in this article. The double-sided junction-to-case thermal resistance (Rthjc) is measured based on the transient dual interface method (TDIM). By analyzing the physical meaning of double-sided Rthjc, the single-sided Rthjc is derived based on the heat flow ratio between both sides. The thermal network model with two IGBT modules sandwiched between three water-cooled heatsinks is established by considering the thermal resistance of the water cooling system. The bidirectional heat transfer characteristic and the thermal coupling effect of PP IGBT modules are analyzed to propose the Tj estimation method. Based on a half-bridge inverter, the feasibility and accuracy of the online Tj estimation method are validated by comparing Tj estimated by the proposed model with the temperature measured by thermocouple. The absolute error for online Tj estimation of PP IGBTs is within 2.1°C.