Fuel Consumption Analysis and Optimizing of a Heavy Duty Dual Motor Coaxial Series-Parallel Hybrid Lorry under C-WTVC

Energy saving is becoming one of the most important issues for the next generation of commercial vehicles. The fuel consumption limits for commercial vehicles in China have stepped into the third stage, which is a great challenge for heavy duty commercial vehicles. Hybrid technology provides a promising method to solve this problem, of which the dual motor coaxial series parallel configuration is one of the best options. Compared with parallel configuration, the powertrain can not only operate in pure electric or parallel mode, but also can operate in series mode, which shows better flexibility. In this paper, regulations on test cycle, fuel consumption limits and calculation method of the third stage will be introduced in detail. Then, the quasi-static models of the coaxial series parallel powertrain with/without gearbox under C-WTVC (China worldwide transient vehicle cycle) are built. The control strategies are designed based on engine and motor performance. The comprehensive fuel consumptions of configurations with different structures and control parameters are calculated by simulation to figure out the possible technology roadmap to meet the regulated fuel consumption limits. Sensitivity analysis is also conducted to show which structure parameter can most effectively reduce the fuel consumption. Results show that a 31 tons coaxial series parallel hybrid lorry with a four speed gearbox can realize fuel consumption of 26.07 L/100km under C-WTVC.