With tighter emission regulations for road vehicles pushing the technology forward, fuel savings are indirectly affecting the designs and technical solutions of loader cranes. By decentralizing the hydraulic power through driving each actuator separately, the goal of a more efficient crane drive is strived for. This thesis analyzes if the simple concept of a pump-controlled cylinder directly driven by an induction motor is achievable for a loader crane. Further, the crucial role of the induction motor is studied both mathematically and physically. A special research is also performed on energy efficiency and the capability of electric energy regeneration. By forming the transfer function of the system and performing measurements on a physical setup, the conclusion is drawn that the proposed pump-controlled cylinder concept is fully functional for its purpose which implies that the technology is promising. The report identifies a number of complications with this configuration, such as the induction motor demonstrating reduced performance at high loads and low speeds. Suggestions of improvements are presented with regards to these issues. The thesis also demonstrates high efficiency during a lifting motion and that the possibility of efficient electric energy regeneration is achievable if an optimum lowering speed is considered.

The desire to use more energy efficient heavy equipment in the earth-moving industry has rapidly increased due to higher environmental awareness. Studies within electrification and new types of hydraulic circuit architecture has shown great potential regarding energy savings. The advantages of implementing a closed, pump-controlled, hydraulic system for controlling the boom cylinder on the back-hoe of an articulated backhoe loader is evaluated in this thesis. The possibilities of electric energy regeneration is investigated and to what extent energy savings can be expected for the complete hydraulic system during normal operation. In order for pump-controlled systems to even be conceivable alternatives to conventional valve-controlled system, they must be able to achieve the same characteristics and driveability as the original valve-controlled systems. The possibilities of imitating the characteristics of a valve-controlled hydraulic system with hydro-mechanical pressure feedback is also investigated in this thesis. The original characteristic is able to be imitated with the implemented pump-controlled system with simple means by defining the current characteristic as the relationship between the operator input, cylinder load and cylinder flow. The evaluated sectioned hydraulic system demonstrates energy savings of 30% during both a light and a heavy duty cycle. With components more suitable for this type of system and an improved control strategy, energy savings of over 50% compared to the original system is believed to be possible.

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The main purpose of this thesis was to develop and evaluate Key Performance Indicators (KPIs) and battery usage associated with Lithium-ion Battery Energy Storage Systems (LiBESS) used as Frequency Containment Reserve (FCR). The investigation was based on three of Vattenfall´s LiBESS projects that use the same lithium-ion battery technology but vary in system rating and configuration. It was found that two of the most important KPIs are response time and energy efficiency. The response time describes how fast the system can respond to changes in grid frequency. Additionally, the energy efficiency describes how effectively the system can provide energy storage during service and it can be parametrized into the efficiency of the battery, converter and transformer. The results show that all the considered LiBESS can fulfill the response time requirements of 30 seconds for FCR provision. In the future stricter requirements for the response time in grid stabilization services will most likely be required. Nevertheless, the results showed that a well configured LiBESS can provide response times on the millisecond scale. The energy efficiency evaluation showed that the system energy efficiency decreased from 89% to 85% when the power increased from 50% to 100% of rated power. At 75% of rated power it was found that the converter had the lowest efficiency (92%) based on the analysis of the efficiency of all the system components. It was also found that the power consumed by auxiliary loads was nearly constant for the examined power rates and that it significantly reduced the energy efficiency. Lastly, the battery usage analysis showed that the battery often idles or operates at low power rates if the frequency dead-band of ±10 mHz is applied around the nominal value of 50 Hz. Moreover, the battery usage can be characterized by an average State of Charge of 50% and a maximum Depth of Discharge of 30% during both charge and discharge of the batteries.