Electrohydraulic Drive with a Flow Valve Controlled by a Permanent Magnet Synchronous Motor

This article presents an electrohydraulic drive with a new electrohydraulic flow valve controlled by a Permanent Magnet Synchronous Motor (PMSM), designed and built by the authors. In comparison to a valve with a proportional electromagnet, the use of a PMSM has enabled significant improvements in the key characteristics of the valve. A theoretical framework and a model of a PMSM are presented; subsequently, a valve with this motor is proposed and tested. Step responses of the real valve and its static and frequency characteristics are measured. The characteristics obtained in the simulation are compared with those obtained in the laboratory investigations, showing their good compliance. The obtained characteristics of the new valve are better than those of a typical proportional valve. The new valve is applied in an electrohydraulic linear actuator. For positioning tasks, two types of controllers are applied and compared: a proportional-derivative controller and a fractional order proportional-derivative controller showing satisfactory parameters

A Thermal Analysis of Direct Driven Hydraulics

This paper focuses on thermal analysis of a direct driven hydraulic setup (DDH). DDH combines the benefits of electric with hydraulic technology in compact package with high power density, high performance and good controllability. DDH enables for reduction of parasitic losses for better fuel efficiency and lower operating costs. This one-piece housing design delivers system simplicity and lowers both installation and maintenance costs. Advantages of the presented architecture are the reduced hydraulic tubing and the amount of potential leakage points. The prediction of the thermal behavior and its management represents an open challenge for the system as temperature is a determinant parameter in terms of performance, lifespan and safety. Therefore, the electro-hydraulic model of a DDH involving a variable motor speed, fixed-displacement internal gear pump/motors was developed at system level for thermal analysis. In addition, a generic model was proposed for the electric machine, energy losses dependent on velocity, torque and temperature was validated by measurements under various operative conditions. Results of model investigation predict ricing of temperature during lifting cycle, and flattened during lowering in pimp/motor. Conclusions are drawn concerning the DDH thermal behavior

Study of Permanent Magnet Synchronous Motor With LQG Controller and Observer On The Hydraulic Pump System

In today's aircraft industry, the flight control system and landing gear system cannot be separated from the role of the hydraulic technology system. As the prime mover of the hydraulic pump or actuator hydraulic system, a permanent magnet synchronous motor (PMSM) is used. This PMSM is a substitute for the role of conventional combustion engines, and PMSM is considered to have several advantages in increasing performance and efficiency. This research will develop a system to find parameter values for Linear Quadratic Gaussian (LQG) controllers in a hydraulic pump system that is installed as a load from PMSM and then observe and analyze the performance of the response of the synchronous motor system, namely in the form of changes in rotor rotation speed, torque electric power, and stator current on the q-axis. The results of the research on the characteristics of the PMSM implemented in the hydraulic pump system show that the LQG controller is more optimal when compared to the observer controller. The LQG controller is known to have a faster transient response, which is indicated by the value of the settling time improvement at no load, namely 116.67% for the observer controller and 364.705% without the controller. Then when the synchronous motor serves the nominal load, the rotational speed of the rotor produced in the steady state becomes 8.29% faster than the observer controller and 74.49% without the controller. This rotor's rotational speed affects the time the actuator needs to extend and retract motion

Electric-driven Zonal Hydraulics in Non-Road Mobile Machinery

The goal of this research is to apply direct-driven hydraulics (DDH) to the concept of zonal (i.e., locally and operation-focused) hydraulics, which is an essential step in the hybridization and automation of machines. DDH itself aims to combine the best properties of electric and hydraulic technologies and will lead to increased productivity, minimized energy consumption and higher robust performance in both stationary and mobile machines operating in various environments. In the proposed setup, the speed and position control of a double-acting cylinder is implemented directly with an electric motor drive in a closed-loop system without conventional control valves and an oil tank. The selection of the location of the hydraulic accumulator and connection of the external leakage lines will also be part of this study. Simulations and experimental research to study the details of the hydromechanical and electrical realization of the DDH are performed

An Alternative Nonlinear Lyapunov Redesign Velocity Controller for an Electrohydraulic Drive

This research aims at developing control law strategies that improve the performances and the robustness of electrohydraulic servosystems (EHSS) operation while considering easy implementation. To address the strongly nonlinear nature of the EHSS, a number of control algorithms based on backstepping approach is intensively used in the literature. The main contribution of this paper is to consider an alternative approach to synthetize a Lyapunov redesign nonlinear EHSS velocity controller. The proposed control law design is based on an appropriate choice of the control lyapunov function (clf), the extension of the Sontag formula and the construction of a nonlinear observer. The clf includes all the three system variable states in a positive define function. The Sontag formula is used in the time derivative of our clf in order to ensure an asymptotic stabilizing controller for regulating and tracking objectives. A nonlinear observer is developed in order to bring to the proposed controller the estimated values of the first and the second time output derivatives. The design, the tuning implementation and the performances of the proposed controller are compared to those of its equivalent backstepping controller. It is shown that the proposed controller is easier to design with simple implementation tuning while the backstepping controller has several complex design steps and implementation tuning issue. Moreover, the best performances especially under disturbance in the viscous damping are achieved with the proposed controller

Improving Energy Efficiency and Motion Control in Load-Carrying Applications using Self-Contained Cylinders

Because of an increasing focus on environmental impact, including CO2 emissions and fluid spill pollution, inefficient hydraulic systems are being replaced by more environmentally friendly alternatives in several industries. For instance, in some offshore applications that have multiple diesel generators continuously running to produce electricity, all hydraulic rotating actuators supplied from a central hydraulic power unit have been replaced with AC induction motors containing a variable frequency drive and gearbox. However, hydraulic linear actuators are still needed in most load-carrying applications mainly because of their high reliability associated with external impact shocks. Moreover, their force capacity is higher than that of their linear electromechanical counterparts. Valve-controlled linear actuators (cylinders) supplied from a centralized hydraulic power unit are standard in offshore load-carrying applications. In addition to the advantages mentioned above of hydraulic linear actuators, they have, nevertheless, a number of important drawbacks, which include: 1) a high level of energy consumption due to significant power losses caused by flow throttling in both the pipelines and valves, 2) reduced motion performance due to the influence of load-holding valves, 3) high CO2 emissions and fuel costs related to the diesel generator that supplies electricity to the hydraulic power unit, 4) significant potential for hydraulic fluid leakage because of many leakage points, 5) demanding efforts with respect to installation and maintenance, as well as 6) costly piping due to the centralized hydraulic power supply. The work presented in this dissertation and the appended papers are devoted to replacing inefficient hydraulic linear actuation systems traditionally used in offshore load-carrying applications with more environmentally friendly solutions. Two alternative technologies are identified, namely electro-mechanical and electro-hydraulic self-contained cylinders. The feasibility of replacing conventional valve-controlled cylinders with self-contained cylinder concepts is investigated in two relevant case studies.publishedVersio

Active suspension control of electric vehicle with in-wheel motors

In-wheel motor (IWM) technology has attracted increasing research interests in recent years due to the numerous advantages it offers. However, the direct attachment of IWMs to the wheels can result in an increase in the vehicle unsprung mass and a significant drop in the suspension ride comfort performance and road holding stability. Other issues such as motor bearing wear motor vibration, air-gap eccentricity and residual unbalanced radial force can adversely influence the motor vibration, passenger comfort and vehicle rollover stability. Active suspension and optimized passive suspension are possible methods deployed to improve the ride comfort and safety of electric vehicles equipped with inwheel motor. The trade-off between ride comfort and handling stability is a major challenge in active suspension design. This thesis investigates the development of novel active suspension systems for successful implementation of IWM technology in electric cars. Towards such aim, several active suspension methods based on robust H∞ control methods are developed to achieve enhanced suspension performance by overcoming the conflicting requirement between ride comfort, suspension deflection and road holding. A novel fault-tolerant H∞ controller based on friction compensation is in the presence of system parameter uncertainties, actuator faults, as well as actuator time delay and system friction is proposed. A friction observer-based Takagi-Sugeno (T-S) fuzzy H∞ controller is developed for active suspension with sprung mass variation and system friction. This method is validated experimentally on a quarter car test rig. The experimental results demonstrate the effectiveness of proposed control methods in improving vehicle ride performance and road holding capability under different road profiles. Quarter car suspension model with suspended shaft-less direct-drive motors has the potential to improve the road holding capability and ride performance. Based on the quarter car suspension with dynamic vibration absorber (DVA) model, a multi-objective parameter optimization for active suspension of IWM mounted electric vehicle based on genetic algorithm (GA) is proposed to suppress the sprung mass vibration, motor vibration, motor bearing wear as well as improving ride comfort, suspension deflection and road holding stability. Then a fault-tolerant fuzzy H∞ control design approach for active suspension of IWM driven electric vehicles in the presence of sprung mass variation, actuator faults and control input constraints is proposed. The T-S fuzzy suspension model is used to cope with the possible sprung mass variation. The output feedback control problem for active suspension system of IWM driven electric vehicles with actuator faults and time delay is further investigated. The suspended motor parameters and vehicle suspension parameters are optimized based on the particle swarm optimization. A robust output feedback H∞ controller is designed to guarantee the system’s asymptotic stability and simultaneously satisfying the performance constraints. The proposed output feedback controller reveals much better performance than previous work when different actuator thrust losses and time delay occurs. The road surface roughness is coupled with in-wheel switched reluctance motor air-gap eccentricity and the unbalanced residual vertical force. Coupling effects between road excitation and in wheel switched reluctance motor (SRM) on electric vehicle ride comfort are also analysed in this thesis. A hybrid control method including output feedback controller and SRM controller are designed to suppress SRM vibration and to prolong the SRM lifespan, while at the same time improving vehicle ride comfort. Then a state feedback H∞ controller combined with SRM controller is designed for in-wheel SRM driven electric vehicle with DVA structure to enhance vehicle and SRM performance. Simulation results demonstrate the effectiveness of DVA structure based active suspension system with proposed control method its ability to significantly improve the road holding capability and ride performance, as well as motor performance

Reducing energy consumption of hammering with electric excavators

Abstract. The aim of this master’s thesis is to research methods to reduce the energy consumption of hammering with electric excavators. To understand the energy consumption of hammering, the structure and energy consumption of a conventional excavator is explained thoroughly. The knowledge of a conventional excavator also lays foundation for studying the electric excavator. An electric excavator is not yet a widely used machine so different operating principles and models are presented in the work. Different technologies are described for utilizing electricity in hammering. Energy consumption of hammering is researched by measurements of the current situation. Measuring the power losses in hammering brings forward the challenges in the conventional hydraulic system and the excavator use in hammering. In addition to the measurements, hammer concepts are designed utilizing the technology researched. Quantitative and qualitative properties of the concepts are reviewed. The size of the power losses of hammering can be seen in the results of the measurements. The magnitude of the losses depend on what type of hammering work is done. The different hammering concepts bring large potential in reducing the energy consumption. The concepts also have new features, which can affect the productivity. The technology used in the different concepts still needs to be researched more and desired features deter- mined. The measurements show the magnitude of power losses in this excavator, but a working cycle should be determined to measure the energy consumption.Iskuvasaroinnin energiankulutuksen pienentäminen sähköisellä kaivinkoneella. Tiivistelmä. Tämän työn tavoitteena on tutkia tapoja, jolla iskuvasaroinnin energiankulutusta pystytään pienentämään sähköisellä kaivinkoneella. Iskuvasaroinnin energiankulutuksen ymmärtämiseksi työssä perehdytään perinteisen kaivinkoneen rakenteeseen ja energiankulutukseen. Perinteiseen kaivinkoneeseen perehtyminen luo myös pohjaa sähköisen kaivinkoneen toiminnan ymmärtämiseen. Sähköinen kaivinkone ei ole vielä yleisesti käytetty laite, joten sen eri toimintaperiaatteita käsitellään tässä työssä. Erilaisia teknologioita esitetään siihen, kuinka sähköä voidaan hyödyntää iskuvasaroinnissa. Iskuvasaroinnin energiankulutusta tutkitaan myös kokeellisesti. Tehohäviömittaukset iskuvasaroinnissa tuovat esiin tämän hetken ongelman kaivinkoneen hydrauliikkajärjestelmässä ja kaivinkoneen käytöstä iskuvasaroinnissa. Mittausten lisäksi työssä suunnitellaan sähköenergiaa hyödyntäviä iskuvasarakonsepteja. Konsepteja arvioidaan sekä energiatehokkuden kannalta että laadullisesti. Mittaustulokset tuovat esiin hydraulisten häviöiden suuruuden. Eri tyyppisissä iskuvasaroinnissa tehohäviöt ovat eri suuruisia johtuen kaivinkoneen hydrauliikasta. Eri konseptit tuovat suurta potentiaalia energiankulutuksen pienentämiseen sähköä hyödyntäen. Konseptit tarjoavat myös uusia ominaisuuksia rikotukseen. Konsepteissa käytettäviin teknologioihin pitää syventyä jatkossa vielä tarkemmin ja halutut laadulliset ominaisuudet tulee määrittää. Mittaustulokset osoittavat häviöiden suuruuden, mutta energiankulutuksen mittaamiseksi tulisi määrittää työsykli iskuvasaroinnille

Series Hybrid Mining Loader with Zonal Hydraulics

Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper