| Energy saving and emission reduction has been put on the agenda on a global scale, using a hybrid power system has become an important and effective way for hydraulic excavator to save energy and reduce emissions. In recent years, foreign manufacturers spared no effort in the development of hybrid hydraulic excavator, the company and research institute in our country also keep pace. Master the hybrid technology of hydraulic excavator which has independent intellectual property rights is a significant thing. In this paper, several studies for parallel hybrid power system in hydraulic excavator carried out:(1) For the shortcomings of current research in hybrid power system, a dynamic model of entire hybrid power system including diesel engine and motor/generator was built. Based on the cylinder combustion dynamics, the transient model of four -cylinder diesel engine was built emphatically. The dynamic model of hybrid power system provided a good foundation for the development and optimization of control strategy.(2) The typical load of hydraulic excavators was analyzed. Based on the typical load, optimized multi-fuel economy work point control strategy was used, and for the permanent magnet synchronous motor/generator, space vector control method was used to control its output speed and torque quickly and accurately.(3) The throttle step response of diesel engine was tested on the platform to verify the effectiveness of the dynamic model of diesel engine; multi-fuel economy work point control strategy of parallel hybrid power system was tested on the platform to verify the effect of energy saving.
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