| Range-extended electric vehicle exhibits great advantages such as low cost, excellent fuel economy, low emission, range extendibility and less infrastructure investment demand. It is not only a significant direction to which automotive industry evolves, but also the optimum solution for a transition to the pure electric vehicle. The engine cabin is the primary location in a range-extended electric vehicle where every thermal source interacts with each other. For this reason, the thermal management of engine cabin has an immediate impact on vehicle performance and emission characteristics. Therefore, how to construct a highly efficient engine cabin thermal management system has always been a vital part in the development of range-extended electric vehicle.Firstly, current developing status and trend of thermal management technology are discussed in this study. Starting from the consideration upon the engine cabin, an integrated thermal management system which is highly efficient and complete, with interflowing circulation, is designed for a research-team-owned range-extended minivan. This system consists of engine cooling system, generator cooling system, driving motor cooling system, HVAC system, and power battery module thermal management system.Aiming at the engine cabin system structure of range-extended electric vehicles, the paper studied and analyzed the power output of engine, generator, driving motor and battery in various driving cycles. Typical data points are extracted out of driving cycles as limit working conditions for parameter matching purpose in the design process of the thermal management system. By analyzing the thermal equilibrium relationships between major devices in a typical engine cabin thermal system, basic thermal loading calculation method of systems of engine, generator, motor, battery and HVAC is established. The interaction and influence between them exist not only in the engine cabin airflow space, but also interact in liquid working fluid of some subsystems. Thermal characteristics and parameters determination are further studied by typical subsystem thermal interaction analysis.The heat dissipation requirements and relevant parameter matching are emphatically analyzed through selected typical working conditions, which include heat dissipation requirements of engine, generator, driving motor and battery pack operating in high temperature; Cooling requirement of HVAC system; Heating requirement of battery pack and HVAC system operating in low temperature. Temperature condition of basic thermal management mode is further clarified. System parameter matching and key components are determined.To further validate the feasibility and temperature controllability of as-designed integrated thermal management system in extreme operation conditions, an integrated thermal managing system model of the range-extended electric vehicle is built on the platform of AMEsim, which contains engine cooling, battery pack cooling and pre-heating, motor electric cooling, as well as HVAC cooling and heating element models and modules. By correlatively coupling each thermal flow subsystem modules, simulation of thermal managing system for the interaction process is conducted. Brief analysis for temperature variation in each thermal process in specific working conditions, while setting environment temperature as the main external factor, is presented by typical calculation examples. Performance optimization and rationality validation of the integrated system are also conducted. |
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