Article
Optimal Design of Accumulator Parameters for an
Electro-Hydrostatic Actuator at Low Speed
Gexin Chen
1,2,
*, Gengting Qiu
1
, Guishan Yan
1
, Tiangui Zhang
1
, Huilong Liu
1
, Wenbin Chen
1
and Chao Ai
1
Citation: Chen, G.; Qiu, G.; Yan, G.;
Zhang, T.; Liu, H.; Chen, W.; Ai, C.
Optimal Design of Accumulator
Parameters for an Electro-Hydrostatic
Actuator at Low Speed. Processes 2021,
9, 1903. https://doi.org/10.3390/
pr9111903
Academic Editor: Arkadiusz Gola
Received: 31 August 2021
Accepted: 20 October 2021
Published: 26 October 2021
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
1
School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China;
gengtingq@stumail.ysu.edu.cn (G.Q.); gsyan@stumail.ysu.edu.cn (G.Y.); tianguiz@stumail.ysu.edu.cn (T.Z.);
huilongl@stumail.ysu.edu.cn (H.L.); wenbinchenysu@163.com (W.C.); aichao@ysu.edu.cn (C.A.)
2
Mechanical and Electrical Engineering, Xinjiang Institute of Engineering, Urumqi 830023, China
* Correspondence: jygxchen@ysu.edu.cn; Tel.: +86-0991-7977195
Abstract:
The electro-hydrostatic actuator (EHA) is a type of highly integrated, compact, closed pump
control drive system composed of a servo motor, a metering pump, a hydraulic cylinder and other
components. Compared with the traditional valve control system, the electro-hydrostatic actuator
has the advantages of a high power-to-weight ratio, high integration, environmental friendliness, and
superior efficiency and energy saving. However, due to the complex mechanical–hydraulic coupling
mechanism of the system and the existence of non-linear multi-source disturbances, the dynamic
and static performance of the system is limited, particularly the pressure pulsation phenomenon
under low-speed conditions, which seriously affects the high precision control requirements of the
system. In order to address the low-speed pressure pulsation problem of the electro-hydrostatic
actuator, first, the mathematical models of the servo motor, metering pump and hydraulic cylinder
are established, and the simulation model of the EHA system is created based on MATLAB/Simulink.
Second, from aspects of the servo motor and the quantitative piston pump, the causes of the pressure
pulsation under low-speed working conditions are analyzed, and the parameter selection method of
the accumulator is proposed to eliminate the pressure pulsation based on
ω
n
and
ζ
of the EHA system.
Finally, the optimal charging pressure of the accumulator is simulated and experimentally analyzed.
The simulation and experimental results show that the charging pressure range of the accumulator
calculated with this method can effectively improve the pressure pulsation phenomenon of the
EHA system under low-speed working conditions, and it plays a positive role in the engineering
popularization and application of the EHA system.
Keywords:
electro-hydrostatic actuator (EHA); pressure pulsation; accumulator; cogging torque;
flux harmonics
1. Introduction
The electro-hydrostatic actuator (EHA) is a type of high-performance servo drive
device originating from the field of aviation. It has the advantages of a high power-
to-weight ratio, low operation and maintenance costs, environmental friendliness, and
superior efficiency and energy saving [
1
]. It has been successfully applied in automobile
active suspension [
2
], tank guns [
3
], robots [
4
], ships [
5
] and in other fields. However,
the EHA system uses the concept of a servo motor driving a metering pump for volume
speed regulation. The coupling mechanisms between the mechanical, electronic and fluid
components in the EHA system are complex; at the same time, due to the time-varying
parameters of the external load, the internal leakage of the system, the oil compressibility
and other non-linear factors, the dynamic and static performance of the system is limited,
particularly with regard to the pressure pulsation problem under low-speed operating
conditions. This issue seriously restricts the popularization and application of the system.
With a view to investigating the pressure pulsation phenomenon inside the system under
low-speed output conditions, researchers started with the causes of the pressure pulsation,
Processes 2021, 9, 1903. https://doi.org/10.3390/pr9111903 https://www.mdpi.com/journal/processes
