Research on energy saving control strategy of parallel hybrid loader

• Four main control strategies of hybrid electric wheel loader are compared.
• Theoretical fuel consumption is compared to simulation results.
• Simulation results demonstrate the more feasible strategies for real control system.
• The theoretically best strategy can be applied to guide optimization.

Hybrid technology is a new energy saving method for wheel loaders. Currently, several energy management strategies (EMSs) have been applied to hybrid electric wheel loaders (HEWLs). Four main EMSs are available, namely, engine optimal control strategy (EOCS), minimum motor power control strategy (MMPCS), motor optimal control strategy (MOCS) and instantaneous optimal control strategy (IOCS). Analyzing and comparing the energy saving effects of these strategies are necessary to guide their application in parallel HEWLs. To determine the EMS, the characteristics of hydraulic torque converter which affects the torque distribution were analyzed, and the model was established by AMESim. Using the AMESim and Matlab/Simulink co-simulation platform, the four EMSs were carried out, respectively. In the simulation, the fuel economy of EOCS and MMPCS was improved by over 10%, and it is better than that of MOCS and IOCS, which were seriously influenced by the battery charge. Accordingly, EOCS and MMPCS were recommended for application.