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This study experimentally investigates the energy flow characteristics of a fuel cell (FC) hybrid electric heavy-duty truck under user-defined driving cycles. The analysis comprehensively examines three critical aspects including energy consumption distribution patterns, efficiency metrics of key powertrain components, and thermal management system performance. The results show that the FC stack achieves 47.98% conversion efficiency but suffers 49.6% thermal losses through coolant systems with power fluctuations, resulting in only 38.99% of initial energy reaching the wheels after accounting for losses in power electronics, transmission and auxiliary systems. The power battery effectively balances loads but achieves only 26.1% energy recovery during deceleration and motor efficiency drops below 85% during medium-speed and low-torque operation in intermediate gears, indicating optimization potential for both energy recovery and shift strategies. Thermal management challenges emerge throughout the system with FC coolant temperature variations correlating with current changes while maintaining 10 °C differentials during load fluctuations. Under the current cooling configuration, the maximum temperature of the battery cell rose to 35 °C. Meanwhile, the motor temperature increased from 27 °C to 50 °C and then stabilized at 45-50 °C. Although the system achieved basic thermal management, there are limitations in handling the heat load at the battery end, indicating the need to further improve the cooling design by increasing cooling capacity or optimizing algorithms. Additionally, the 2-4 °C cabin temperature variations and compressor instability highlight heating, ventilation and air conditioning system needs for outlet redesign or control strategies enhancements. This study constructed a brand-new energy flow analysis framework for FCHE, which not only quantifies energy consumption distribution and powertrain component efficiency, but also conducts in-depth analysis of the thermal management system from multiple dimensions such as temperature response, heat loss mechanism, and subsystem coordination. This research also provides a reference for the subsequent improvement of the performance and engineering application of FC hybrid heavy-duty trucks.
Feng et al. (Wed,) studied this question.