Comparing Heating Systems for Degradation-Aware Battery Thermal Management in Electric Minibuses: PTC Heater vs. Heat Pump

Battery thermal management is critical for electric vehicles operating in cold climates, where low temperatures reduce battery efficiency, limit regenerative braking and accelerate degradation. This study compares PTC heater and heat pump systems for battery thermal management in electric minibuses using optimization-based control strategies. A control-oriented model of the vehicle thermal system, validated against chassis dynamometer measurements, and a heat pump system model, validated against testbed measurements, are used to optimize thermal management strategies via nonlinear programming, minimizing energy consumption while accounting for Joule losses, regenerative braking energy and thermal system consumption. Battery degradation is evaluated using a Doyle-Fuller-Newman (DFN) electrochemical model incorporating physics-based degradation mechanisms. Results show that optimized thermal management strategies can simultaneously reduce energy consumption and degradation. With the PTC heater system, only marginal improvements are achievable, and further reductions in degradation come at the cost of increased energy consumption. In contrast, the more efficient heat pump system enables simultaneous reductions in both degradation and energy consumption through optimized thermal management. These findings highlight that advanced thermal management leveraging heat pump systems can enhance both driving range and battery lifetime in cold-climate electric vehicle operations.