Real-time compact electronic thermal modelling for health monitoring

Temperature monitoring and management is emerging as an important tool for through-life cost optimization of high reliability power electronic systems. When combined with physics of failure based reliability analysis, such techniques can be employed to provide functions such as life consumption monitoring and prognostic maintenance scheduling. Requisite elements of such schemes are real-time electro-thermal models that can be used to predict the temperatures of device junctions, interfaces etc. that cannot ordinarily be measured during service. This paper presents a real-time reduced-order thermal model and its application to a half-bridge IGBT module including its associated thermal management system. Real-time electro-thermal modelling of the junction temperatures is accomplished using simplified circuit representations for the thermal model and look-up tables for the device loss estimation. The model is applied to a PWM modulated, current controlled full-bridge and implemented in dSPACE using a multi-rate computational process to improve efficiency. Validation is accomplished by comparing the model results with temperatures obtained from a high speed infra-red camera. Results are presented comparing the performance of the model for a range of PWM modulation inputs, including low frequency sine and square waves.