Sensorless Individual Cell Temperature Measurement by Means of Impedance Spectroscopy Using Standard Battery Management Systems of Electric Vehicles
Lithium ion technology is state of the art for actual hybrid and electrical vehicles. It is well known that lithium ion performance and safety characteristics strongly depend on temperature. Thus, reliable temperature measurement and control concepts for lithium ion cells are mandatory for applications in electrical cars. Temperature sensors for all individual cells increase the battery complexity and cost of a battery management system. Normally, temperature is measured on module level in current battery packs, without observation of the individual cell temperature. Sensorless cell impedance-based temperature measurement concepts have been published and are validated in laboratory studies. Dedicated test equipment is usually applied, which is not useful for automotive series application. This work describes a practical approach to enable impedance-based sensorless internal temperature measurement for all individual cells using state-of-the art battery management system components.