Supercapacitor Electrical and Thermal Modeling, Identification, and Validation for a Wide Range of Temperature and Power Applications

Supercapacitors benefit from unique features including high power density, long cycle life, wide temperature operation range, durability in harsh environments, efficient cycling, and low maintenance cost. This paper presents a validated lumped and computationally efficient electrical and thermal model for a cylindrical supercapacitor cell. The electrical model is a two-state equivalent electric circuit model with three parameters that are identified using temporal experiments. The dependence of the parameters on the state of charge, current direction and magnitude (20-200 A), and temperatures ranging from -40 °C to 60 °C is incorporated in the model. The thermal model is a linear 1-D model with two states. The reversible heat generation which is significant in double-layer capacitors is included in the thermal model. The coupling of the two models enables tuning of the temperature-dependent parameters of the electrical model in real time. The coupled electrothermal model is validated using real-world duty cycles at subzero and room temperatures with root-mean-square errors of (82 mV-87 mV) and (0.17 °C-0.21 °C) for terminal voltage and temperature, respectively. This accurate model is implementable in real-time power applications and also thermal management studies of supercapacitor packs.