| Summary: | Electric construction machinery can achieve zero emissions and be pollution free in the process of construction. In an electric excavator, to make full use of the output power of the power source, the output power of the electric motor (EM) should be absorbed by a hydraulic pump on the most attainable level. Therefore, constant power control is generally employed to achieve power matching between the power source and hydraulic pump. In this paper, considering the shortcomings of a single constant power point in a traditional load sensing system of electric construction machinery, combining the discharge characteristics of the li-ion battery and the overload capability of EM, a piecewise constant power control strategy is proposed to realize the organic unity of power and safety for a novel electric construction machinery power train system. The control strategy is verified by simulations and experiments. The results show that the system can not only satisfy the large power output but also ensure the normal and stable operation of the system when the electric excavator meets the heavy load through the piecewise constant power control. The proposed control strategy improves the dynamic performance of the system on the basis of ensuring the safety of the system.
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