Development of a heat flow sensor for battery electric vehicle (BEV) investigations

This paper describes the development of a ceramic heat flow sensor with gold-platinum thermocouples. The sensor was developed to investigate the thermal behaviour of lithium-ion batteries in electric vehicles. To adapt the sensor properties, in particular the thermal resistance, we created an equivalent model based on the electro-thermal analogy and the given requirements. In addition to geometric parameters, the significance of thermal conductivity of the individual materials was experimentally determined. A uniform cell, that fulfils the requirements in terms of thermal resistance was successfully developed by optimizing the model using optiSLang. The uniform cell consists of an Au-Pt thermocouple embedded in a ceramic carrier material and can be assembled into a larger sensor by multiplication. The design principle underlying this approach allows scalability. The article describes the final sensor design comprising both a three-dimensional resistance thermometer that enables the measurement and compensation of the average temperature and a thermopile for heat flow measurement.