Effect of Energy Recovery on Efficiency in Electro-Hydrostatic Closed System for Differential Actuator

Abstract

This paper investigates energy efficiency and dynamic behavior through simulation and experiments of a compact electro-hydrostatic actuator system (EHA) consisting of an electric motor, external gear pump/motors, hydraulic accumulator, and differential cylinder. Tests were performed in a stand-alone crane in order to validate the mathematical model. The influence and importance of a good balance between pump/motors displacement and cylinder areas ratios is discussed. The overall efficiency for the performed motion is also compared considering the capability or not of energy recovery. The results obtained demonstrate the significant gain of efficiency when working in the optimal condition and it is compared to the conventional hydraulic system using proportional valves. The proposed system presents the advantages and disadvantages when utilizing components off-the-shelf taking into account the applicability in mobile and industrial stationary machines.

Integral Sliding Mode Backstepping Control of an Asymmetric Electro-Hydrostatic Actuator Based on Extended State Observer

“…where ⁄ is the angular acceleration; J is the rotational inertia of boom. Decomposed Equation (1) to obtain the output force equation of the hydraulic cylinder [15] =…”

“…According to the system (15), it can be known that the system feedback output is the state , and the tracking trajectory is defined as = . Hence, the position tracking error of the EHA can be represented as…”

“…To solve this problem, many novel methods were proposed such as the development of asymmetric flow distribution pumps [13], the research of pump-valve-coordinated system [14] and the use of dual-pumps control system [15], and on the other hand, advanced control algorithms such as robust adaptive control [16][17][18], backstepping control and sliding mode control.…”

Active Disturbance Rejection Control for Double-Pump Direct-Driven Hydraulics

“…The parameters of the DDH are shown in Table 2. Firstly, the experimental data from reference [10] is used to verify the accuracy of the mathematical model of DDH. The comparison between the simulation results of the mathematical model and the experimental results show that the position curve is basically consistent, as shown in Figure 3a.…”

“…However, in the pump-controlled differential cylinder system, unbalanced flow is caused by the unequal effective cross-section area of the two chambers. Much research has been carried out on this, such as using a pilot-operated check valve or solenoid-operated reversing valve [7,8], developing an asymmetric flow distribution pump [9], and proposing a double-pump or multi-pump compensation circuit [10][11][12] to solve the flow imbalance problem. Among them, the double-pump direct-driven hydraulic (DDH) system can better improve the dynamic performance and stability of the system.…”