Mobile machinery energy efciency and emission pollution are the national and worldwide issues. This paper contributes in solving these problems by applying a speed variable power source. Unfortunately, almost all of the speed variable systems have the dynamic response problem when the motor starts with full load or heavy load. To address this problem, a hydraulic accumulator is used to balance the load of the power source for assisting starting of the motor and a matching method combined with speed and displacement control of the pump is proposed to improve the energy efciency and dynamic performance simultaneously under diferent working conditions. Also, the power source/valve combined control strategy of an independent metering system is designed to realize fow matching of the whole system. Firstly, a test system is established to study the dynamic performance and energy efciency of the speed variable power source with an auxiliary accumulator. Working performance and energy consumption of the power source under diferent rotating speeds and diferent loads are studied. And then, the hydraulic excavator test rig with the proposed system is constructed. Furthermore, the working performance of the excavator with the speedfxed and speed-variable strategy are studied comparatively. Results show that, compared with fxed-speed strategy, the electric power consumption during the idle period and partial load condition can be reduced about 2.05 kW and 1.37 kW. The energy efciency of speed variable power source is about 40%-71%, which is higher than that of the fxed-speed power source by 3%-10%.
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