Electro-Hydraulic Variable-Speed Drive Networks—Idea, Perspectives, and Energy Saving Potentials

Schmidt, Lasse; Hansen, Kenneth

doi:10.3390/en15031228

Cited by 12 publications

(10 citation statements)

References 50 publications

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“…Regarding the A2FM, the measured flow losses account for both cross-port leakage flow and drain flows. It is assumed that the flow losses are evenly distributed in the reference measurements and that these can be scaled to relevant displacement unit sizes using scaling laws [2,10]. The scaling of the EMS1 assumes that the efficiency map is invariant with respect to the motor size i.e., that any motor has the same efficiency map as the reference EMS1-20, with the axes scaled to the max.…”

Section: Loss Models Used In Case Studiesmentioning

confidence: 99%

“…Even though many hydraulic systems contain more than a single cylinder, limited attention has so far been given to dedicated multi-axis electro-hydraulic drives. This field has, however, begun to emerge in the last few years ranging from solutions combining displacement units in variable-speed and/or displacement-controlled cylinders with valve-controlled cylinders in a mix [6,7] to more disruptive drive design approaches such as the so-called HHEA [8,9] and so-called electro-hydraulic variable-speed drive networks [10][11][12]. The latter approach generally contains a tremendous amount of possible drive architectures, with this number increasing exponentially with the number of cylinders (or motors) in a system.…”

Section: Introductionmentioning

confidence: 99%

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Energy Efficient Excavator Functions Based on Electro-Hydraulic Variable-Speed Drive Network

Schmidt,

Binsbergen-Galán,

Knöll

et al. 2024

14th International Fluid Power Conference

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Electrification of mobile working machines is subject to increasing focus in both industry and academia. At this stage, focus has been the replacement of conventional internal combustion engines with cable or battery fed electric motors driving the main pump(s), and the replacement of rotary functions with electro-mechanical drive solutions. However, the linear functions remain controlled by hydraulic control valves resulting in substantial throttle losses, which in turn necessitates large battery sizes and/or low machine uptimes. Alternatively, the valve-controlled hydraulic cylinders may be replaced with electro-mechanical solutions in applications with limited forces, whereas heavy duty working machines such as medium/large excavators may benefit from standalone electro-hydraulic primary controlled drives, i.e., variable-speed standalone drives. The use of such solutions will substantially increase efficiency due to the absent/limited throttle control and the ability to share power through the electric supply/DC-bus. A main drawback is that each axis needs to be designed to meet both the maximum force and maximum speed, hence in the case of using single motor standalone drives, each motor and associated inverter needs to be designed to meet both the maximum force and maximum speed, potentially rendering these somewhat large. Alternatively, dual motor standalone drives can be applied, enabling power distribution via more motors. However, the use of numerous motors requires more extensive system integration and potentially large motor power installations considering industrially available non-specialized components. This paper presents a novel so-called electro-hydraulic variable-speed drive network, applied for actuation of three linear functions of an excavator implement. Cylinder chamber short-circuiting's and electro-hydraulic variable-speed units constitute a drive network allowing both electric and hydraulic power sharing. The drive network is realized with Bosch Rexroth A2 displacement units and eLION electric motors as its core components. Results demonstrate that the proposed drive network is realizable with similar energy efficiency as a standalone dual motor electro-hydraulic drive solution, but with less motor power and with fewer motors, displacement units and integration effort, rendering this a more sustainable and cost-efficient solution. Finally, it is shown that the proposed drive network is superior in terms of installed displacement, electric motor power and energy efficiency, compared to a separate metering valve drive supplied by a battery fed electro-hydraulic pump.

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Section: Loss Models Used In Case Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energy Efficient Excavator Functions Based on Electro-Hydraulic Variable-Speed Drive Network

Schmidt,

Binsbergen-Galán,

Knöll

et al. 2024

14th International Fluid Power Conference

View full text Add to dashboard Cite

show abstract

“…Another alternative for electric-powered hydraulic systems is presented in [17]. Here the discussion revolves around controlling two cylinders with multiple fixed pumps connected to different chambers of the actuators and powered by variable-speed electric motors, a system denominated as an electro-hydraulic variable-speed drive network.…”

Section: Current Research On Electrified Systemsmentioning

confidence: 99%

A Novel Multi-Pump System for Hydraulic Actuation in Electric Mobile Machinery

Gama

Heybroek

Ericson

2023

Linköping Electronic Conference Proceedings

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An observable trend nowadays is the change in the prime movers of mobile heavy machinery to electric alternatives to achieve more eco-friendly equipment. These solutions often require large and heavy batteries with limited capacity, making the research of more efficient components and the development of different system architectures an important topic of study. Hydraulic actuation is still a relevant application for these vehicles because of its reliability, controllability, and high power density. The electrification and digitalization of mobile machinery allow for innovative designs and control strategies to be implemented that take advantage of electro-hydraulic systems and their characteristics. Similar research has shown that a higher number of degrees of freedom allow for the system to operate with higher total efficiency. This paper introduces a novel actuation architecture that combines multiple fixed displacement hydraulic pumps and on/off directional valves to control the position and force of two hydraulic actuators for the working functions of a mobile machine. Each pump is powered by a variable speed electric drive so that each one can be operated independently, and together with the set of directional valves, allows the selection of different combinations of pumps and flow sharing between the actuators’ chambers to achieve the desired flow and pressure on each cylinder. The multi-pump system favours the use of smaller pumps, and the possibility of combining their flows reduces the need to operate the components at lower efficiency points such as partial displacement. At the same time, controlling the pumps’ flow through the variable-speed electric motors means that throttling valves are not needed. The development of this architecture will allow for its use in mathematical models to analyse its behaviour and efficiency and to obtain insights regarding points of improvement in the system architecture.

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“…In [4] Schmidt and Hansen introduce the concept of multi-cylinder/motor drives connection as a variable-speed drive network. Electrical and hydraulic interconnected variable-speed displacement units allow for the complete avoidance of throttle elements, while also for the sharing of auxiliary functions and fluid reservoirs, as well as hydraulic and electric power.…”

Section: Of 28mentioning

confidence: 99%

Power Drives Architectures for Industrial Hydraulic Axes: Energy Efficiency-based Comparative Analysis

Tiboni

2023

Preprint

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In hydraulic systems, energy dissipation can be significant. The pressure drops that can occur in the hydraulic circuit, influenced by the adopted drive architecture, result in an absorbed power often significantly greater than that required by the mechanical system. In this paper, a comparative study of energy efficiency among five drive common architectures in industrial hydraulic axes is carried out. The analysis is applied to a hydraulic blanking press with variable speed and force, a fairly frequent industrial system, e.g. in the production of semi-finished brass products. Standard, regenerative, high-low, variable displacement pump and variable speed drive for a fixed displacement pump configurations have been analysed and compared. An adequate and optimized sizing of the various components of the system has been carried out in each case and subsequently the energy consumption has been estimated for a load cycle common to all the considered cases. The results show that the choice of power generation architecture of the hydraulic system has a very significant impact on energy efficiency and consequently operating costs and carbon footprint. The performed quantification of the potential energy efficiency of the considered drive architectures can be very useful in guiding energy-conscious choices.

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Electro-Hydraulic Variable-Speed Drive Networks—Idea, Perspectives, and Energy Saving Potentials

Cited by 12 publications

References 50 publications

Energy Efficient Excavator Functions Based on Electro-Hydraulic Variable-Speed Drive Network

Energy Efficient Excavator Functions Based on Electro-Hydraulic Variable-Speed Drive Network

A Novel Multi-Pump System for Hydraulic Actuation in Electric Mobile Machinery

Power Drives Architectures for Industrial Hydraulic Axes: Energy Efficiency-based Comparative Analysis

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