This is an electronic reprint of the original article.This reprint may differ from the original in pagination and typographic detail.

Powered by TCPDF (www.tcpdf.org)

This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user.

Minav, Tatiana; Heikkinen, Jani; Pietola, MattiDirect driven hydraulic drive for new powertrain topologies for non-road mobile machinery

Published in:Electric Power Systems Research

DOI:10.1016/j.epsr.2017.08.003

Published: 01/01/2017

Document VersionPublisher's PDF, also known as Version of record

Published under the following license:CC BY-NC-ND

Please cite the original version:Minav, T., Heikkinen, J., & Pietola, M. (2017). Direct driven hydraulic drive for new powertrain topologies for non-road mobile machinery. Electric Power Systems Research, 152, 390-400.https://doi.org/10.1016/j.epsr.2017.08.003

Direcnon-r

T.A. Mia School of Eb Independe

a r t i c

Article histoReceived 22Received inAccepted 2Available on

Keywords:DriveDirect driveEnergy efficTopologyNon-road mServomotorVariable spHydraulics

1. Introd

Energing as a

valve-conand lowemachinerpact, efficapplicatiotrial hydrdemand,

nologicaland imprments. Hsolutionsples of NRthese, theand fuel

Abbreviery; SOC, st

∗ CorrespE-mail a

http://dx.do0378-7796/0/).

Electric Power Systems Research 152 (2017) 390–400

Contents lists available at ScienceDirect

Electric Power Systems Research

j o ur nal ho me page: www.elsev ier .com/ lo cate /epsr

t driven hydraulic drive for new powertrain topologies foroad mobile machinery

nava,∗, J.E. Heikkinenb, M. Pietolaa

ngineering, Department of mechanical engineering, Aalto University, P.O. Box 14400, Finlandnt Researcher, Helsinki, Finland

l e i n f o

ry: July 2015

revised form 24 August 2016 August 2017

line 10 August 2017

a b s t r a c t

Tightening of emission rules and a desire to improve energy efficiency pushes even further the need forhybridization of non-road mobile machinery (NRMM). Consequently, this paper illustrates potential ofthe application of directly driven hydraulic drive (DDH) for NRMM from an energy efficiency point of view.The control of the DDH system was implemented directly with a servomotor driving a pump withoutconventional hydraulic control valves. Angular speed of the servomotor, in-coming oil flow from thepump, and out-going flow to the hydraulic motor determined the velocity of the double-acting cylinderpiston. An earlier study by the authors presented that the hydro-mechanical losses were dominant in

n hydraulicsiency

obile machinery

eed drive control

the original DDH setup. Resulting theoretical investigation indicated that the best scenario efficiencyfor DDH was estimated to be 76.7%. Therefore, this paper provides a detailed analysis based on Sankeydiagrams of various powertrain topologies with DDH. This study of powertrains illustrated that DDHhas the highest impact with 174% efficiency improvement with an electric NRMM powered by batteriesinstead of a conventional topology.

© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).

atsuitachevedcallyhanictric mlengerline

cost ineraevelM is

atterpecia

to d

uction

y efficiency is becoming crucial in all fields of engineer-result a tightening of emission rules [1]. At present,trolled hydraulic systems with throttled pressure, lossesr efficiency are applied commonly in Non-road mobiley (NRMM). Currently, industry is investigating for com-ient and powerful solutions for control and powertrainns in NRMM. Similar demands are recognized in indus-

aulics where a flexible layout of production, lower energyand avoidance of additional heat and noise. New tech-

solutions are needed to further reduce fuel consumptionove energy efficiency to fit new governmental require-ybrid technology has been identified to be one of the key

to achieve these targets. There are already some exam-

KomA HachiTypimecelecchalundeand

of gethe dNRMto b– esneed

MMs in the market that provide hybrid solutions [2,3]. In hybridization targets mainly in improving performanceeconomy. In [4], a 20-ton parallel hybrid excavator by

ations: DDH, direct driven hydraulics; NRMM, non-road mobile machin-ate of charge.onding author.ddress: Tatiana.minav@aalto.fi (T.A. Minav).

ture. Rec[7–9], ascustomeris underl

Beforesized theto utilizeand only

i.org/10.1016/j.epsr.2017.08.003© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the C

with supercapacitor achieved up to 41% energy savings.i serial hybrid loader with a battery as energy storage

energy savings of 25–30% depending on the cycle [5]., the diesel engine is running hydraulic pumps and theal powertrain. In these, the diesel can be supported byotor/generator located after the diesel engine. In [6] thes faced by researchers and NRMM manufacturers wered, such as energy storage, control of generation energyn general. These provide new dimensions into the controltion and distribution of electric energy. On the other hand,opment of an electric and plug-in powertrain proposal for

facing identical problems in the automotive sector relatedy technology and its charging issues. In electric vehicleslly passenger cars but also busses – there is now urgentefine charging systems and develop needed infrastruc-

ent research concentrates on charging of electric vehicles this is essential in order to ensure wider acceptance bys and facilitate more electric vehicles on roads. This need

ined also by politics in EU. these solutions enter wider markets, it can be hypothe-

re will be a need to have even more sophisticated means

electric energy for creating hydraulic pressure on board when it is required. Currently, a trend for a decentral-

C BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.

T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400 391

Fig. 1. DDH (a) Simplified schematics of the test setup: a—double-acting cylinder, b—wire-actuated encoder, c—pressure sensor, d—reversible gear pump/motor P1,e—pressure sensor in tank line, f—torque sensor, g- T-gear, h—torque sensor, (i) PMSM motor/generator, j—current and voltage probes, k—frequency converter, l—oil tank,m—hydraulic accumulator, n—pressure sensor, o—reversible gear pump/motor P2 and p—pressure sensor in the tank line. *Sensors are utilized for system diagnostic purposeonly. (b) PMSM motor/generator connected through T-gear into two internal gear motor/pumps [20], (c) experimental setup.

ud

idRs

q

d

Ls

Lmd

iPM

iD

RD

id+iD+iPM

LDmd

uq

iq Rsd

q

Ls

Lmq

iQ

RQ

iq+iQLQmq

iPM

its of P

ized powhybrid cisystems wthe marketems are

their sizeand torqunities, com

effices [1ertraonse

Fig. 2. Equivalent circuits of circu

er network opens up new approaches for hydraulic- andrcuits for NRMM [10–12]. As a result, electro-hydraulic

ith motor- or pump-controlled systems are observed ont and research areas [13–18]. These electro-hydraulic sys-

highvalvpow

C

attracting an attention of industry due to advantages of-to-power ratios and the ability to produce large forcee only on demand. These technologies provide opportu-pared with traditional systems, a compact structure and

systems

ciency anNRMM sysetup (DD

MSM [25].

iency with a speed regulation loop without conventional9,20]. All these features can be beneficial in creating newin topologies in NRMM.quently, the development of electro-hydraulic compact

motivates current research activities, however no effi-alysis was found concerning their application in thestems. Therefore, the effect of a direct driven hydraulicH) on the efficiency of a variety of powertrain topologies

392 T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400

Fig. 3. Efficiency chart of the utilized servomo

F

is investilating, orand calcu

This pprincipleical systemeasuremponent eSankey dthe conveand 5 con

2. Test sdriven hy

SimplFig. 1a. Thwith duaposition o

pump/mof the sesecond pVIEW prohydraulic

The psetup is aas the ‘enquency coand estimencoder

Hioki 339the voltasure tranused to m

of thIRO

8M-0p, as

nstrfor the teshe fopone

baseidedoachts is

Syste

he prolle

ig. 4. Efficiency chart of different hydraulic pump types [28].

gated in this paper. This study is realised by either calcu- measuring the efficiencies of various used componentslating their common effect on the topologies.aper structure as follows. In Section 2 scheme and thes of the DDH system are described in detail with a theoret-m component evaluation and validation of efficiencies by

ents. Topologies of NRMM’s powertrains and their com-fficiencies are introduced in a system study in Section 3.iagrams are utilized in Section 3 to analyze efficiency ofntional and alternative powertrain topologies. Section 4tains discussion and concluding remarks.

etup description: detail introduction of directdraulics

tionby M(IV5setuof coties

of thT

comtemprovapprmen

2.1.

Tcont

ified schematics of DDH test setup are demonstrated ine setup uses a speed-controlled electric servomotor drive

l rotating hydraulic pump/motors to directly control thef the double-acting cylinder via a T-gear. First hydraulic

setup is

Techniquvomotor

capability

tor in DDH setup.

otor P1 creates a flow depending on the rotating speedrvo motor and, simultaneously with the same speed, theump/motor P2 pumps oil out from the cylinder. A Lab-gram for the electric drive controls both the electrical and

sides of the system.ower source of the frequency converter in the currentn electric network, and an embedded brake resistor actsergy storage’. For the measurements of the system, a fre-nverter software was utilised to record the rotating speedated torque of the PMSM with help of an incremental

as the motor rotor position feedback. A power analyser0 with a sampling time of 50 �s was utilised for measuring

ges, currents and active powers. Gems 3100R0400S pres-sducers [21], installed at the pump’s inlet and outlet, was

easure system pressures. The actual velocity and posi-e cylinder’s piston rod (C-10-60/30 × 400 manufactured

) were measured with a wire-actuated encoder SIKO SGI039) [22]. Utilised components were chosen for the testthey were readily available or fast to purchase at the timeuction. The components do not have any specific proper-is kind of application. Figs. 1b and c illustrate photographst setup.llowing Section 2.1 introduces an evaluation of the DDHnts in detail and illustrates the efficiency of the test sys-d on background research and theoretical information

by component manufacturers with the best scenario in mind. A theoretical evaluation verified by measure-presented in Section 2.2.

m component evaluation

rime mover of the DDH system is an electric machined by a frequency converter. The servomotor in the DDH

a 3 kW PMSM (Unimotor 115U2C) by Emerson Controles [23]. In general, permanent magnet synchronous ser-is characterized by its high efficiency and high overload. Estimation for the total efficiency of the servomotor was

T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400 393

Input : energy100.0 [%]

Electrical machinelosses: 5.0 [%]

Pump losses14.2 [ %]

Cylinder losses: 4.0 [%]

Output: mechanical energy76.7 [ %]

Fig. 5. Best scenario Sankey diagram of the DDH setup (efficiency of the frequency converter is not included).

temp

made basfor a PMS

Fig. 3

based onhave largciency islrated powtion to dioperating

In thea frequenniques [2motion c97–98%.

ext

aulicent oeforeauliced diy. Thps. Aydra

ship bp/mo

Fig. 6. Total efficiency of DDH in ambient

ed on the motor parameters and vector equivalent circuitsM illustrated in Fig. 2. For detail explanation see Ref. [24].illustrates the efficiency chart for the servomotor made

the estimation. The efficiency contours are closed ande areas with efficiencies above 90%. Moreover, the effi-ands are typically located in areas of nominal speed ander. In electric motor’s case it may also be similar situa-

esel engine that the motor–controller combination is not in its optimum area.

experimental study of the DDH, a 400 V servomotor withcy converter Unidrive SP1406 by Emerson Control Tech-

Nhydrconttherhydra fixtivelpumthe htionpum

6] was utilised. The Unidrive provides speed, torque, andontrol for the servomotor with efficiency in the range of

pressure

take intowith time

erature +20 ◦C [19].

DDH setup components under investigation are the ones. Main hydraulic component is the pump. In thef this research, a hydraulic motor is utilised as a pump,, it will be named pump/motor. In the experiments, two

motors of type XV–2 M by Vivoil [27] were utilised withsplacement of 14.4 and 22.8 cm3/rev for P2 and P1 respec-ese hydraulic motors are also capable of working as according to Fig. 4, depending on the operating point ofulic pump/motor unit on its performance curve, the rela-etween flow and hydraulic losses varies significantly. Thetor internal leakage increases with the higher operating

and lower fluid viscosity. These variables are difficult to account in the calculation of unit efficiency as they vary

and temperature. Therefore, in our test setup, the power

394 T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400

Fig of 175 kg (efficiency of the frequency converter is not included) [19].

losses in

scenario

A dousetup. Cylosses asstroke. Frpressure

temperatto Ref. [292–5% of twas assu

A mecpumps/mvalue doethereforetric cableneglectab

Takingcies, the DFig. 5 illulowing efand doubverter is n

Followare utilise

2.2. DDH

This sments. Inefficiencyhydraulicfor the topayload oFig. 6 poscorresponof lifting

to the pothe recovhave beeexplainedefficiencying, total

speed an

ig. 7

or spcy c

ompon o

rovem poteid traown

owe

ectioin to

Eachas inummnativns of

Pow

ost

aulicaulicaulicsmis

. 7. Measured Sankey diagram of the DDH with motor speed 300 rpm and payload

pump/motor are assumed to be 15% based on the bestapproach.ble-acting cylinder is utilised as the actuator in the DDHlinder’s overall efficiency is dependent on the frictionalsociated with the piston and the rod moving during itsictional losses depend on multiple characteristics such asdifference across the seal and its material, sliding velocity,ure, time, wear, and direction of the movement. According] total seal friction of a hydraulic cylinder varies between

he total cylinder force, therefore, the cylinder efficiencymed to be 95% for the best scenario approach.hanical T-gear is utilized as a coupling between the twootors and its efficiency varies between 98% and 99%. Thiss not significantly affect the total efficiency of the DDH;, this value is neglected from analysis. For this study, elec-

losses and hydraulic pipe losses were also consideredle and omitted.

into account all the components’ best scenario efficien-DH setup overall efficiency can be estimated to be 76.7%.

strates the best scenario of the DDH considering the fol-ficiencies: pump/motor – 85%, electrical machine – 95%le-acting cylinder −95% (efficiency of the frequency con-ot included).ing Section 2.2 introduces measurement results whichd for validation of efficiency values.

efficiency measurements

ection presents analysis of the DDH based on measure- order to determine the behaviour of the DDH system,

charts for the lifting and lowering operations of the boom are created. Fig. 6 displays the measurement resultstal efficiency. The experimental setup was tested with af 175 kg with a motor speed range from 300 to 500 rpm. Initive motor speed corresponds to lifting, negative speedsd to lowering motions. The electro-hydraulic efficiency

is defined as a ratio of the input energy from the motortential energy of the load, and for lowering as a ratio ofered energy to the potential energy. The efficiency curvesn calculated from the measured data by using equations

Fmotquen

CmatiimpThishybrto kn

3. P

Sertra2.1).ilar

are saltermea

3.1.

Mhydrhydrhydrtran

in detail in [19]. As illustrated in Fig. 6, the total lifting varies with motor speed from 50 to 20%. During lower-efficiency is in the range of 8–32% depending on the motord payload.

Depentem, the

from its

combusti

Fig. 8. Conventional powertrain.

illustrates the measured Sankey diagram of the DDH witheed 300 rpm and payload of 175 kg (efficiency of the fre-onverter is not included).arison Figs. 7 and 5 illustrates a significant underesti-f hydro-mechanic losses and the same time potential of

ent of DDH by better sizing and selection of components.ntial is especially highlighted in application of DDH fornsmissions. Therefore, following Section 3 will apply DDH

powertrain topologies as a system study.

rtrain study

n 3.1 begins by presenting the single components of pow-pologies which were not mentioned earlier (in Section

component is analysed from efficiency point of view sim- Section 2.1. Efficiencies for the following system studiesarised in the end of the section. Section 3.2 introduces thee powertrain’s topologies and their efficiency analysis by

Sankey diagrams.

ertrain components

of the operations functions in NRMM are powered bys. Usually, in conventional machines the powering of the

pump is achieved directly with a combustion engine. The pump and the combustion engine are connected using a

sion and a coupling as illustrated in Fig. 8.

ding on the working cycle and dimensioning of the sys-engine may be most of its operation time very far awayoptimum efficiency. Fig. 9 illustrates example of a dieselon engine efficiency map. According to Ref. [20], diesel

T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400 395

0.160.18

0.2

0.20.220.24

0.26

0.26

0.280.28

0.3

0.3

0.32

0.32

0.34

0.34

0.36 0.36

, [ rad/s]

T, [N

m]

80 100 120 140 160 180 200 220 2400

10

20

30

40

50

60

Fig. 9. Example of the diesel combustion engin

0.53

745

0.55

807

0.57

868

0.59

930.

6199

10.

6405

30.

6611

50.

6817

60.

7023

8

0.70

238

0.72

299

0.72

299

0.743

61

0.74

361

0.764

22

0.76

422

0.784

84

0.78

484

0.805

45

0.805

45

0.82607

0.826

07

0.82

607

0.84668

0.84668

0.846

68

0.846

680.8

673

0.8673

0.8673

0.8673

0.88791

0.88791

0.88791

0.88791

0.90853

0.908530.90853

0.92914

0.929140.92914

0.94976

0.949760.94976

0.970370.97037 0.97037

Cur

rent

, A

0 10 20 30 40 50 60 70 80 90 10 0

50

100

150

200

250

300

350

Fig. 10. Calculated efficiency chart of a lithium–titanate battery [31].

combusticycle is nefficiencytotal efficcally low

A conunit for othe oil flociency of

conventio

leakage. Iare assum

So farvantagesfor poweisation ofrequired.Fig. 10 illbic efficiehigh statecovers wthe analy

In follthe currethe overatopologie

Pow

his salterains

ey dario

igs. 1al ann ba

iency of the NRMM system was calculated by multiplying the

on engine operating efficiency depending on the workingormally about 20%, and that is only half of the maximum

40% in optimum operating region. Due to this fact, theiency of any powertrain based on an engine is automati-.ventional proportional control valve is the main controln-board hydraulics, which ensures correct direction of

3.2.

Tand

contSankscen

Ftionregioeffic

w in the system. It was demonstrated in Ref. [30] that effi-a hydraulic boom is only 60% due to the characteristics ofnal valves, which have high flow resistance and internal

individuabrief predifferent

e efficiency map.

n this study, valve losses follow the best-case scenario anded to be 20%.

, a conventional powertrain was introduced and its disad-. To meet CO2 requirements, hybrid and electric solutionsrtrains are created. Alternative sources of energy for real-

new topologies for non-road mobile machinery are also In this research, battery is chosen as a source of energy.ustrates an example of lithium-titanate battery’s Coulom-ncy. Highest efficiency region is located in low current and

of charge regions. According to Ref. [31], efficiency of 95%orking region of NRMM and this value will be utilized forsis.owing Section 3.2 are the component efficiency datas fromnt section and Section 2.1. These were utilized to calculatell efficiencies for the conventional and alternative NRMMs.

ertrain topologies’ efficiency analysis

ection introduces the efficiency analysis of conventionalnative powertrains by means of Sankey diagrams. Table 1summary of the utilized theoretical efficiencies for theiagrams. Table 1 is the prime source of data to define bestoperation conditions for NRMM.1–14 demonstrate theoretical efficiencies for the conven-d alternative NRMM powertrains in optimum operatingsed on the above-mentioned data. The theoretical total

l component’s efficiencies. Each subsection ends with asentation of how the change of components effects thepowertrains.

396 T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400

Fig. 11. (a) Schematics of cconventional powertrain, (b) Sankey diagra

Table 1Maximum theoretical efficiencies and losses of powertrain components in %.

Component Maximum theoreticalefficiency, [%]

Diesel engine efficiency 40Electrical machine (generator andmotor) efficiency

95

Hydraulic pump efficiency 85Valve losses 20Hydraulic cylinder efficiency 95Frequency converter/rectifierefficiency

97

Measured DDH efficiency 50Best scenario DDH efficiency 76.7Lithium t

Fig. 1input ene

Accordpowertracarded asis 25.8% i

In ordNRMM sanalysed

Fig. 12erator (Gengine caIn this toto DDH, wFig. 12b

ciency. Inengine. F

topologyscenario

which is s25.8%.

Fig. 13and genequency cmachine.thru conv

Fig. 13topologyare due to

overen po

Fig.ne ispply

batteal hyctua

ig. 14is popareDH in

46.1ollowrovemges i

itanate battery efficiency 95

1 illustrates a conventional powertrain, where 100% isrgy from fuel.ing to Fig. 11, significant concentration of losses of the

in is located in diesel engine, where 60% is generally dis- heat loss. Total system efficiency in conventional NRMMn optimal operational region.er to compare the disadvantages of the conventional

ystem, the proposed hybrid and electric topologies are in identical way.a displays a hybrid topology for NRMM with DDH. Gen-

) collects energy generated by the engine; as a result then be forced to constantly work in the high-efficiency zone.pology energy is transferred using direct current directly

fact,driv

Inengito suthe

tionper a

Fof thcomof Dfrom

Fimpchan

here the actuator is driven directly by an electrical motor.illustrates hybrid powertrain with measured DDH effi-

this topology, DDH losses are second biggest after theig. 12c presents the theoretical efficiencies of the hybrid

4. Discu

The exachieved

m of the conventional NRMM powertrain.

with the best case scenario of the DDH. The best casetotal efficiency of the powertrain of this system is 27.5%,lightly higher compared to the conventional powertrain’s

a presents the electric version where the original enginerator of the NRMM was replaced with a battery. A fre-onverter is used to supply and control the electrical

Pump delivers the flow to all the actuators in the systementional valves that control the actuator motions.b illustrates the Sankey diagram for the electric NRMM

with a conventional hydraulic line. Most significant losses the valves in hydraulic section of the system. Despite thisall efficiency is higher compared to conventional enginewertrain (Fig. 11a).

14a is illustrated the second electric approach where the replaced with a battery, frequency converter is utilised

the ac network of the machine, control the charging ofries and maintain voltage levels in the system. Conven-draulics including the valves are replaced with the DDHtor.b illustrates a Sankey diagram where the total efficiencywertrain topology is 46.1% which is significantly higher

d to the conventional system. By applying the best scenario Fig. 14c, efficiency of the electric powertrain is increased% to 70.7%.ing section contains overall discussion about possibleents in the powertrain, which can be achieved by

n the utilized topology.

ssion

perimental investigation of the DDH demonstrated that measured performance was up to 50%. However, the lim-

T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400 397

Fig. 12. (a) Schematics of hybrid powertrain with a DDH, (b) Sankey diagram of the series hybrid powertrain with measured DDH efficiency, (c) Sankey diagram of the hybridpowertrain

iting factoof 76.7% cthe DDH.optimisatple, with

17.9 to 2from 46.1

Combpowertranents and

ario

all efrom

rolled onhat e

with best case scenario DDH efficiency.

r of the DDH is hydraulic losses. The best scenario valuesan be achieved with optimal selection of components for

Based on the Sankey diagrams, it can be seen that theion of the DDH’s total efficiency is important. For exam-DDH optimized, the powertrain efficiency increased from7.5% in hybrid (Figs. 12b and c) and in electric proposal

scenover

Fcontbaseing t

to 70.7% (Figs. 14b and c).ustion engine is clearly the most non-efficient part in anyin and it was shown that optimizing of hydraulic compo-

locating them closer to the actuators (creating the best

techno-eThe c

increase

verting c

DDH) gives an improvement of 7% (Figs. 11b and 12c) officiency of NRMM’s powertrain.electrification of a conventional NRMM with valve-

d hydraulics it is possible to get a 118% improvement comparison of Figs. 11b and 14b. It is worth mention-lectric proposal is limited mainly by battery capacity and

conomical boundaries of today’s technical solutions.omparison of Figs. 11b and 14c indicated that, 174%in overall powertrain efficiency can be achieved by con-onventional NRMM to electric topology with the best

398 T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400

Fig. 13. (a) ram of

case scenbesides thone of thcosts, we

Assumengine is

cycle is vcauses nohybrid toDespite tertrain pr

Thereciency ofis converthat currewithout eopment,

5. Concl

Tightestrates a

M).) effand

suredctionario

o thee DDin w

scenevedeforeponetal in

owl

Schematic of an electric powertrain with conventional hydraulics, (b) Sankey diag

ario of efficiencies of a DDH. Improving efficiency woulde energy savings, reduce the demand of cooling which is

e system issues of today’s machines in terms of volume,ight and maintenance.ptions that efficiency of a combustion engine is constant,

working in its maximum efficiency and excluding workingery optimistic and simplifies things significantly, whichn-significant difference between the conventional andpology with regards to efficiency (Figs. 11b and 12c).

hat, effect of the DDH is clearly visible in the electric pow-oposals.

fore, the study indicates that DDH can increase the effi- NRMM. Its full potential can be only realized if NRMMted to be fully electric. It is important to also mentionnt study analysed only linear movements of NRMM andnergy regenerative features of the DDH. For future devel-

these features should be taken into account.

(NRM(DDHgies

meadirescening tin thertrabestachiThercomis vi

Ackn

usion

r emission and energy efficiency requirements demon- need for hybridization of non-road mobile machinery

The rArcticWEMechanicPanu Sain

the electric NRMM powertrain with conventional lifting cylinder.

This paper investigates a directly driven hydraulic drive’sect on the efficiency of various NRMM powertrain topolo-

analyses them with help of Sankey diagrams. DDH’s energy efficiency varies up to 50% depending on the

of the cylinder’s motion and the motor speed. The bestefficiency for the DDH was estimated to be 76.7%. Accord-

Sankey diagrams, the hydro-mechanical losses dominateH and should be improved. Despite this, the DDH pow-ithout conventional control valves illustrated a 174%

ario increase in overall powertrain efficiency that can be by converting a conventional NRMM to electric topology., further study on optimising the DDH hydro-mechanicalnts and investigation on the regenerative energy modes

order to explore all benefits of proposed powertrains.

edgements

esearch was enabled by the financial support of thell project, and internal funding at the Department ofal Engineering at Aalto University. The cooperation ofio is highly appreciated.

T.A. Minav et al. / Electric Power Systems Research 152 (2017) 390–400 399

Fig. 14. (a) e elecdiagram of

Referenc

[1] EmissiAvaila

[2] VOLVOvolvocwheel%

[3] Komat2008/p

omatontribomat. Och

utom. Lin,

onstr

Schematic of an electric powertrain with DDH hydraulics, (b) Sankey diagram of ththe electric powertrain with best scenario DDH efficiency.

es

on Standards, United States: Nonroad Diesel Engines, [Online].ble: https://www.dieselnet.com/standards/us/nonroad.php.

WHEEL LOADER L220F HYBRID, [Online]. Available: http://www.e.com/SiteCollectionDocuments/VCE/Documents%20Global/20loaders/brochureHybridloader 21A1004471 2008-02.pdf.

[4] Kck

[5] MA

[6] Tc

su, [Online]. Available: http://www.komatsu.com/CompanyInfo/csr/df/04.pdf.

[7] Javier

Guerrefor sm

tric powertrain with measured DDH efficiency during lifting, (c) Sankey

su corporateprofile 2008, PC200-8 hybrid hydraulic excavatorutes to reducing CO2 emissions, [Online]. Available: http://www.

su.eu/displayMagazine.ashx?fileid=59657.iai, Development for environment friendly construction machinery,. Constr. 9 (2003) 24–28.Q. Wang, B. Hu, W. Gong, Development of hybrid powered hydraulicuction machinery, Autom. Constr. 19 (1) (2010) 11–19.

Gallardo-Lozano, M. Isabel Milanés-Montero, Miguel A.ro-Martínez, Enrique Romero-Cadaval, Electric vehicle battery chargerart grids, Electr. Power Syst. Res. 90 (September) (2012) 18–29.

400 earch

[8] D.Q. OelectriRes. 98

[9] Y. Ota,distribSyst. R

[10] J. LodeMobile

[11] J. WebDresde

[12] T. Minwith Z

[13] T.A. MsystemConstr

[14] M. IvanIntern

[15] H. Odastabili7th JFP15–18

[16] T. Minsystem

[17] J. Zhendoi.org

[18] S. Kuchhydrauin: 200Mecha14–17

[19] T.A. MhydrauConfer

. Minth Inermaemssww.

eptemIKO Se, vismersww.rochu. Minizing:nd. El. Pyrhohn Wmersttp://ivoil

ttp://. Kau

Funda.R. McGra. Lian

n: The 5th International Conference on Fluid Power Transmission andontrol, Hangzhou, China, 2001.. Minav, T. Schimmel, K. Murashko, R. Åman, J. Pyrhönen, M. Pietola, Towards

T.A. Minav et al. / Electric Power Systems Res

liveira, A.C. Zambroni de Souza, L.F.N. Delboni, Optimal plug-in hybridc vehicles recharge in distribution power systems, Electr. Power Syst.

(May) (2013) 77–85. H. Taniguchi, J. Baba, A. Yokoyama, Implementation of autonomousuted V2G to electric vehicle and DC charging system, Electr. Poweres. 120 (March) (2015) 177–183.wyks, P. Zurbrügg, Decentralized Energy-Saving Hydraulic Concepts for

Working Machines, IFK, Dresden, Germany, 2016.er, et al., Novel System Architectures by Individual Drives, 8–10 March,n, Germany, 2016, IFK-2016.

av, T. Lehmuspelto, P. Sainio, M. Pietola, Series Hybrid Mining Loaderonal Hydraulics, 8–10 March, Dresden, Germany, 2016.inav, L. Laurila, J. Pyrhönen, Analysis of electro-hydraulic lifting’s energy efficiency with direct electric drive pump control, J. Autom.. 30 (2013) 144–150.tysynova, Innovations in pump design-what are future directions, in:

ational Symposium on Fluid Power, Toyama, 2008., K. Ohtsu, H. Sato, K. Kanehiro, Designing advanced rudder rollzation system—using high power with small size hydraulic system, in:S International Symposium on Fluid Power, TOYAMA 2008, September

, 2008.av, L. Laurila, J. Pyrhönen, Effect of driving electric machine type on the

efficiency of an industrial forklift, in: ICEM, France, Marsel, 2012.g, S. Zhao, S. Wei, J. Cent, South Univ. Technol. 17 (2010) 316 https:///10.1007/s11771-010-0048-9.ler, O. Sawodny, K. Schneider, K. Langer, Vibration damping for alic driven luffing cylinder at a boom crane using feedforward control,9 IEEE/ASME International Conference on Advanced Intelligent

[20] T9G

[21] GwS

[22] Sd

[23] EwB

[24] TsI

[25] JJ

[26] Eh

[27] Vh

[28] H[

[29] SM

[30] XiC

[31] T

tronics, Suntec Convention and Exhibition Center Singapore, July, 2009, pp. 1276–1281.inav, C. Bonato, P. Sainio, M. Pietola, Efficiency of direct drivenlic drive for non-road mobile working machines, 2014 Internationalence on Electrical Machines (ICEM) (2014) 2431–2435.

betterProc. I

152 (2017) 390–400

av, C. Bonato, P. Sainio, M. Pietola, Direct driven hydraulic drive, in: Theternational Fluid Power Conference, 9. IFK, March 24–26, Aachen,ny, 2014.ensors 3100R0400S pressure transducers, [Online]. Available: http://gemssensors.com/Products/Pressure/Pressure-Tranducers, visited on

ber, 2013.GI (IV58M-0039), [Online]. Available: http://www.siko-global.com/en-ited on October, 2013.on Control Techniques Unimotor 115U 2C, [Online]. Available: http://emersonindustrial.com/en/documentcenter/ControlTechniques/res/unimotor fm product data.pdf, visited on September, 2013.

av, L. Laurila, J. Pyrhönen, Permanent magnet synchronous machine effect on the energy efficiency of an electro-hydraulic forklift, Trans.ectron. 59 (June (6)) (2012), 2012.önen, T. Jokinen, V. Hrábovcová, Design of rotating electrical machines,iley & Sons, Chichester, 2008.

on Control Techniques Unidrive SP1406 drive, [Online]. Available:www.emersonindustrial.com, visited on September 8, 2013.motor, Data Sheet: reversible motor – series XV, [Online]. Available:www.vivoil.com/files/xm en/xm201.pdf, visited on September 8, 2013.ranne, J. Kajaste, M. Vilenius, Hydraulitekniikan perusteet.mentals in Hydraulic Technology], WSOY, Helsinki, 2006 (in Finnish).

ajumdar, Oil Hydraulic Systems Principles and Maintaince,w-Hill, 2002, pp. 548.g, T. Virvalo, What’s wrong with energy utilization in hydraulic cranes,

energy efficiency through systems approach in an industrial forklift,MechE, Part D: J. Autom. Eng. 229 (February (3)) (2015) 273–282.