Utilization of electric prime movers in hydraulic heavy-duty-mobile-machine implement systems

Fassbender, David; Zakharov, V. N.; Minav, Tatiana

doi:10.1016/j.autcon.2021.103964

Cited by 33 publications

(18 citation statements)

References 56 publications

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“…However, information on the bulk modulii is uncertain, and the piston velocities are not measured. Hence, estimates of the bulk modulii and the piston velocity references ẋ * 1 , ẋ * 2 , together with Equations ( 35)- (38), are used to estimate the pressure dynamics, with these estimates given by Equations ( 41)- (44). Here, ẋ = [ ẋ1 ẋ2 ] T , ω PP = [ω 1,0 ω 1,2 ω 3,0 ω 3,4 ] T and • * denotes a reference for a given state/input.…”

Section: Vdn-pp Flow Decoupling Schemementioning

confidence: 99%

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

Schmidt

Hansen²

2022

Energies

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Electro-hydraulic differential cylinder drives with variable-speed displacement units as their central transmission element are subject to an increasing focus in both industry and academia. A main reason is the potential for substantial efficiency increases due to avoidance of throttling of the main flows. Research contributions have mainly been focusing on appropriate compensation of volume asymmetry and the development of standalone self-contained and compact solutions, with all necessary functions onboard. However, as many hydraulic actuator systems encompass multiple cylinders, such approaches may not be the most feasible ones with respect to efficiency or commercial feasibility. This article presents the idea of multi-cylinder drives, characterized by electrically and hydraulically interconnected variable-speed displacement units essentially allowing for completely avoiding throttle elements, while allowing for hydraulic and electric power sharing as well as the sharing of auxiliary functions and fluid reservoir. With drive topologies taking offset in communication theory, the concept of electro-hydraulic variable-speed drive networks is introduced. Three different drive networks are designed for an example application, including component sizing and controls in order to demonstrate their potentials. It is found that such drive networks may provide simple physical designs with few building blocks and increased energy efficiencies compared to standalone drives, while exhibiting excellent dynamic properties and control performance.

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Section: Vdn-pp Flow Decoupling Schemementioning

confidence: 99%

“…These include the use of hydraulic energy storages [38] and the use of valves enabling flow regenerative functionalities [39][40][41][42]. Comprehensive reviews on developments of such types of drives are available in [43,44].…”

Section: Introductionmentioning

confidence: 99%

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

Schmidt

Hansen²

2022

Energies

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“…This must also be considered in pump-controlled systems. The problems are well summarised by Fassbender et al in their article about the electrification of hydraulic systems in mobile machinery [85].…”

Section: Auxiliary Functionsmentioning

confidence: 99%

On Electrified Fluid Power Systems in Mobile Machinery

Kärnell

2022

Linköping Studies in Science and Technology. Dissertations

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High power density in combination with flexible power distribution possibilities and extreme robustness are reasons why fluid power has been the preferred technology in mobile machinery, such as excavators and cranes, since the mid-20th century. In principle, the machines have been powered by a combustion engine which powers a pump, with the output from the pump being distributed to different functions via valves. However, a transformation is currently underway. Combustion engines are being replaced by electric motors, and batteries able to store energy corresponding to several hours of operation are often desired. Since batteries tend to be heavy and expensive, reducing the energy consumption is getting higher priority than ever before. There are applications where electrification means that hydraulic components are replaced by electric counterparts, but fluid power has characteristics that are highly desirable in mobile machinery. Therefore, many hydraulic actuators will remain. Conventional hydraulic systems, which are known for their inefficiency, should, however, be adapted to the new conditions brought about by electrification. The question, and the overall subject of this thesis, is: how? The research has focused on two main topics: pump-controlled systems, which are systems where each actuator has its own supply unit, and the use of variable displacement pumps in electrified systems.A large proportion of the losses in many conventional hydraulic systems is due to the simultaneous operation of functions that require different pressure levels. One way to avoid these losses is to use pump-controlled systems. How these systems should be designed is, however, far from obvious. In this thesis, different types of pump-controlled systems are compared, both statically and dynamically.Regarding variable displacement pumps, they have had a natural place in many conventional systems, but electrification may change this, since speedcontrol can now also be used for flow-and pressure control. However, there are still aspects relating to energy consumption and component dimensioning, among other things, that makes variable pumps relevant. These aspects are investigated here, and different types of variable pumps are reviewed.Linköping, August 2022 Samuel Kärnell v vi PapersThe following publications are included in the thesis and can be regarded as its foundation. They will be referred to by their Roman numerals. Apart from formatting changes, they are reproduced in their original form. Notice that they are not appended in chronological order. Instead, they are sorted based on the topics; the first three focus on displacement control and the last two on pump-controlled systems.[I] S. Kärnell and L. Ericson, "Classification and review of variable displacement fluid power pumps and motors," International Journal of Fluid Power (submitted), 2022.[II] S. Kärnell, A. Rankka, A. Dell'Amico, and L. Ericson, "Digital pumps in speed-controlled systems -an energy study for a loader crane application," in

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“…The electrification and digitalization trend of heavy machinery supports the development of both these alternatives. The use of electric batteries with limited capacity requires more frequent and longer recharge times [9] or a complete battery exchange [10]. In this regard, having a hydraulic system with higher efficiency is advantageous, as the machine can operate for longer periods, but also reduce the overall energy cost even for newer or conventional fossil fuel equipment or hybrid solutions, thus also reducing emissions.…”

Section: Introductionmentioning

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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Utilization of electric prime movers in hydraulic heavy-duty-mobile-machine implement systems

Cited by 33 publications

References 56 publications

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

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

On Electrified Fluid Power Systems in Mobile Machinery

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

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