Towards Energy-Efficient Electrified Mobile Hydraulics : Considering Varying Application Conditions
Fassbender, David (2023)
Fassbender, David
Tampere University
2023
Teknisten tieteiden tohtoriohjelma - Doctoral Programme in Engineering Sciences
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Väitöspäivä
2023-08-25
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-03-2952-5
https://urn.fi/URN:ISBN:978-952-03-2952-5
Tiivistelmä
In the face of global warming, companies in all kinds of industries need to take measures to reduce the use of fossil fuels, which is explicitly enforced by more and more upcoming emission legislation in many countries. In the case of heavy-duty mobile machines (HDMMs), a currently high-emitting sector, the most feasible method of reducing harmful emissions during operation is battery-based electrification. However, the relatively low capacities and high costs of available battery packs are restricting the operation times as well as upper power limits of battery-electric HD-MMs—at least under economically feasible conditions. In this scenario, the typically low energy-efficiencies of conventional hydraulic systems, which are essential for realizing linear actuation on HDMMs, are becoming more critical than ever before, and more efficient alternative concepts are required.
As an answer to this demand, this thesis and the six publications on which it is based analyze how alternative hydraulic concepts for electrified HDMMs should look like, and two specific concepts are proposed as well as evaluated. In this scope, the focus is not only on improving the efficiency but also on other aspects that can prevent or accelerate the success of alternative hydraulic concepts on the market, such as costs and feasibility. Since those aspects cannot be analyzed in isolation from the application conditions, the essential characteristics of HDMMs and the differences of those characteristics between HDMM types are elaborated systematically. Furthermore, the implications of the transition from internal combustion engines (ICEs) to electric machines (EMs) as the prime movers for hydraulic pumps are identified by means of a literature review. Considering the insights from the analyses of those aspects, already existing hydraulic concepts—i.e., conventional as well as proposed alternatives for improved efficiency—are reevaluated, and beneficial elements of those concepts are filtered out for constructing two new concepts.
Those two proposed concepts are characterized by a modular approach in which actuators can be valve-controlled, which might be less efficient but more cost-effective, or pump-controlled, as an alternative for more efficient yet costly actuation of selected functions on the HDMM. Simulation studies are used to demonstrate the efficiency of both concepts under varying configurations that are enabled through the modular nature of the concepts, and the differences in applying them on a telehandler, wheel loader, or excavator are analyzed. For the second concept, which is based on displacement-control and performed best in the simulations, a cost analysis is used to prove additionally that reasonably short payback times of the increased investment costs can be reached in different scenarios. Furthermore, the efficiency performance as well as feasibility—in terms of using commercially available components only and achieving good controllability—are experimentally validated on a telehandler.
As an answer to this demand, this thesis and the six publications on which it is based analyze how alternative hydraulic concepts for electrified HDMMs should look like, and two specific concepts are proposed as well as evaluated. In this scope, the focus is not only on improving the efficiency but also on other aspects that can prevent or accelerate the success of alternative hydraulic concepts on the market, such as costs and feasibility. Since those aspects cannot be analyzed in isolation from the application conditions, the essential characteristics of HDMMs and the differences of those characteristics between HDMM types are elaborated systematically. Furthermore, the implications of the transition from internal combustion engines (ICEs) to electric machines (EMs) as the prime movers for hydraulic pumps are identified by means of a literature review. Considering the insights from the analyses of those aspects, already existing hydraulic concepts—i.e., conventional as well as proposed alternatives for improved efficiency—are reevaluated, and beneficial elements of those concepts are filtered out for constructing two new concepts.
Those two proposed concepts are characterized by a modular approach in which actuators can be valve-controlled, which might be less efficient but more cost-effective, or pump-controlled, as an alternative for more efficient yet costly actuation of selected functions on the HDMM. Simulation studies are used to demonstrate the efficiency of both concepts under varying configurations that are enabled through the modular nature of the concepts, and the differences in applying them on a telehandler, wheel loader, or excavator are analyzed. For the second concept, which is based on displacement-control and performed best in the simulations, a cost analysis is used to prove additionally that reasonably short payback times of the increased investment costs can be reached in different scenarios. Furthermore, the efficiency performance as well as feasibility—in terms of using commercially available components only and achieving good controllability—are experimentally validated on a telehandler.
Kokoelmat
- Väitöskirjat [4790]