A 3-D Thermal Network Model for Monitoring of IGBT Modules

With the continuous improvement of power densities and power levels for power converters, temperature information at critical sites of the power modules has become essential in health monitoring and thermal management. However, existing thermal models often ignore the temperature distributions of the chip and rarely discuss their applicability under high-temperature operation conditions. Here, a novel 3-D physical RC network model is proposed for insulated-gate bipolar transistor (IGBT) modules, which considers the temperature effects. This model can be efficiently and conveniently obtained with the assistance of finite-element method (FEM) steady-state thermal simulations. Based on the heat flux curves inside the power module, a novel method for 3-D RC parameters extraction is presented to monitor the temperatures at critical sites of the IGBT chip, and meanwhile, the temperature effects and uneven power loss distribution on the chip are considered. Compared with the prior-art Foster-type temperature-dependent 3-D thermal models, the modeling time cost for the proposed model has been remarkably reduced under the same computing hardware facilities since the temperature responses are no longer needed. Finally, FEM simulation and experimental results verify the effectiveness and accuracy of the proposed 3-D physical RC network model.