throbber
Proceedings of the Institution of Mechanical
`Engineers, Part D: Journal of Automobile
`Engineering
`
`http://pid.sagepub.com/
`
`
`A Hybrid Internal Combustion Engine/Battery Electric Passenger Car for Petroleum Displacement
`I Foster and J R Bumby
`Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering
`DOI: 10.1243/PIME_PROC_1988_202_155_02
`
` 1988 202: 51
`
`The online version of this article can be found at:
`
` http://pid.sagepub.com/content/202/1/51
`
`Published by:
`
`http://www.sagepublications.com
`
`
`
`On behalf of:
`
`Institution of Mechanical Engineers
`
`
`
`Proceedings of the Institution of Mechanical Engineers, Part D: Journal of AutomobileAdditional services and information for
`
`
` can be found at:
`Engineering
`
`Email Alerts:
`
`http://pid.sagepub.com/cgi/alerts
`
`
`
`Subscriptions:
`
`
`http://pid.sagepub.com/subscriptions
`
`Reprints:
`
`http://www.sagepub.com/journalsReprints.nav
`
`
`
`
`
`http://www.sagepub.com/journalsPermissions.navPermissions:
`
`
`
`Citations:
`
`
`http://pid.sagepub.com/content/202/1/51.refs.html
`
`>>
`
`Version of Record
`
`- Jan 1, 1988
`
`What is This?
`
`
`
`  
`    
`
`Page 1 of 15
`
`
`
`Downloaded from Downloaded from
`
`
`
`
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`FORD EXHIBIT 1105
`

`  






`

`

`51
`
`A hybrid internal combustion engine/battery electric
`passenger car for petroleum displacement
`
`1 Foster, BSc, PhD and J R Bumby, BSc, PhD, CEng, MIEE
`School of Engineering and Applied Science, University of Durham
`
`This paper examines the potential of the hybrid electric vehicle in substituting petroleum fuel by broad-based electrical energy. In
`particular a hybrid car is considered. The way in which the powertrain can be controlled and the effect component ratings have on
`achieving the petroleum substitution objective are described. It is shown that a hybrid vehicle can be designed that can achieve a
`petroleum substitution of between 20 and 70 per cent of the equivalent internal combustion engine vehicle, be capable of entering
`environmentally sensitive areas and yet be capable of a range at high and intermediate speeds that is limited only by the size of itsfuel
`tank.
`
`NOTATION
`El energy input to the i.c. engine (J)
`E , energy input to the electric traction system (J)
`F objective function
`9, gear ratio
`L , petroleum energy weighting factor
`L, electrical energy weighting factor
`torque split ratio
`x
`
`defined, for example in urban delivery duty. Indeed, it
`has been in such vehicles as the urban milk delivery
`vehicle or milk float that relatively low performance
`electric traction drives have been traditionally applied
`with a great deal of success. Currently the demand is for
`urban electric vehicles to be developed with greater
`traffic compatibility in terms of speed and range. It is in
`such vehicles as the ‘Freight Rover Sherpa’ and the
`‘Bedford CF‘ one tonne vans that higher performance
`electric drives have started to appear (2).
`Although urban delivery vehicle applications will
`help to reduce the dependence of the road transport
`sector on petroleum-based fuels, the major part of this
`market requires vehicles that are not limited in range
`and have a performance compatible with today’s inter-
`nal combustion (i.c.) engine vehicles. The use of
`advanced traction battery technology to overcome the
`range limitation of electric vehicles is one possible solu-
`tion. However, this would still result in a vehicle limited
`in range and may in itself create additional problems.
`For example, due to the much greater on-board stored
`energy, the charging time required will be greater than
`at present while the higher continuous rating of the
`traction components required to achieve high-speed
`performance compatible with today’s vehicles will need
`careful attention.
`The range limitations of the pure electric vehicle can
`be overcome by using a hybrid i.c. engine/electric drive
`which incorporates both an i.c. engine and an electric
`traction system. Although such a vehicle can be
`designed to meet a number of end objectives, it has been
`argued (3) that a vehicle which seeks to remove the
`range limitation of the electric vehicle while substituting
`a substantial amount of petroleum fuel by electrical
`energy is the vehicle most worth pursuing. With the
`emphasis of the vehicle design biased towards the elec-
`tric drivetrain the intention may be to operate in an
`all-electric mode under urban conditions and to use the
`i.c. engine for long-distance motorway driving. The
`hybrid mode could then be used for extending urban
`improving vehicle accelerative per-
`range and/or
`formance on accelerator kick-down.
`The concept of a hybrid electric vehicle capable of
`substituting petroleum fuel is not new, Bosch (4) and
`Volkswagen (5) having built vehicles in the 1970s. More
`0265-1904/88 $2.00 + .05
`Proc Inst Mech Engrs Vol202 No DI
`
`1 INTRODUCTION
`The disruption to the world’s oil supplies that occurred
`in 1973 and 1978 helped focus international attention
`upon the finite nature of this particular energy resource.
`It also prompted the adoption of energy conservation
`policies and emphasized the need to transfer energy
`demand away from oil to other sources of energy, such
`as natural gas, coal and nuclear. As a result of such
`policies the inland deliveries of petroleum products,
`expressed as a percentage of the total energy consumed,
`dropped from 50 to 40 per cent over the period 1973-85
`(1).
`Although such an energy transfer is feasible in many
`energy sectors, it is more difficult in the transport area,
`due to the operational requirements placed on many of
`the vehicles. Some energy transfer has been achieved in
`the rail system by the use of increased electrification but
`in the road sector such an energy transfer is more diffi-
`cult as the ‘free ranging’ nature of the majority of vehi-
`cles requires the energy store to be on-board the vehicle
`itself. Consequently, in the period 1973-85, the use of
`petroleum in the road transport sector, expressed as a
`percentage of the total inland deliveries of petroleum
`products, increased from 12 to 39 per cent (1).
`A transfer of energy from oil to electricity, with its
`associated broad fuel base, can be achieved to a limited
`extent in the road transport sector by the increased use
`of electric vehicles. However such vehicles are limited in
`range due to the amount of energy that can be realisti-
`cally stored on-board the vehicle without unduly affect-
`ing payload. As a consequence of this, electric vehicles
`must be used in situations where daily usage is well
`
`The MS was received on 7 April 1987 and was accepted for publication on 25
`August 1987.
`22/88 0 IMechE 1988
`
`Page 2 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`FORD EXHIBIT 1105
`
`

`

`52
`
`I FORSTER AND J R BUMBY
`
`
`
`- -
`
`
`
`- -
`
`I
`
`U
`
`
`
`
`
`Engine Engine
`
`
`
`t t
`
`
`
`Transmission Transmission
`
`
`Final Final
`
`drive drive
`
`
`
`I I
`
`
`
`I I
`
`
`
`- -= - -=
`
`
`
`L L
`
`2 THE BASE HYBRID VEHICLE
`Although a large number of hybrid i.c. engine/electric
`traction drive system arrangements are possible the
`configuration selected as having the greatest potential
`for use in a passenger car application is shown in Fig. 1.
`In this parallel arrangement both the electric traction
`motor and the i.c. engine are capable of driving the road
`wheels directly, and independently, through a common
`transmission. Such an arrangement offers the potential
`for maximizing
`the overall
`transmission efficiency
`between either prime mover and the road wheels,
`although, when both prime movers are operative, a
`compromise must be achieved. Although minor gains
`are possible if each power source is fed through its own,
`independent, transmission the efficiency benefit of such
`an arrangement must be carefully balanced against the
`added complexity, weight and cost.
`To examine the potential of the hybrid drive as a
`means of displacing petroleum fuel a set of vehicle
`parameters typical of a mid-range European passenger
`car are defined in Table 1. Included in this table is a
`comparable parameter set for a conventional i.c. engine
`vehicle. Because the hybrid arrangement has two on-
`board energy sources the selection of the engine and
`traction motor rating must be carefully balanced. In this
`base hybrid vehicle specification the i.c. engine is sized
`to meet the maximum level road speed and is capable of
`sustaining 120 km/h on a 2 per cent gradient. The elec-
`tric traction motor is rated so as to give adequate all-
`electric performance and also, when combined with the
`i.c. engine, provides the required acceleration demand
`placed on the vehicle. This value is comparable with
`that of a similar i.c. engine vehicle. The performance
`curves for the i.c. engine and the traction motor selected
`are shown in Fig. 2. Also shown in Fig. 2 is the com-
`bined torque capability of the drive system and the road
`load requirement in top gear. Throughout this paper,
`whenever any changes are made to the size of a com-
`ponent the installed power capacity of the vehicle is
`
`Accelerator
`
`Brake
`
`Controller
`Controller
`
`Motor
`Motor
`
`I
`
`recently, the advent of the Electric and Hybrid Vehicle
`Research, Development and Demonstration Pro-
`gramme in the United States of America initiated the
`design and construction of a Near Term Hybrid Vehicle
`(NTHV) with the principal aim of substituting pet-
`roleum fuel by ‘wall plug’ electricity (6, 7).
`As part of the NTHV programme a large number of
`conceptual studies were conducted but on vehicles
`aimed at the American passenger car market. In this
`paper optimization studies were conducted, but now on
`a vehicle suitable for the European medium-sized pass-
`enger car market. Such optimization studies are impor-
`tant as, with two sources of traction power available,
`the way in which they are controlled, and their relative
`sizing, is fundamental to the way the vehicle performs.
`In order to optimize the control and component
`rating of the hybrid drivetrain, the performance and
`energy consumption of
`the vehicle over standard
`driving cycles is assessed using the road vehicle simula-
`tion program Janus (8). Janus is a flexible road vehicle
`simulation program capable of predicting the energy
`use and performance of vehicles with a variety of
`powertrain configurations and has been used previously
`to study the performance of advanced i.c. engine vehi-
`cles (9) and hybrid electric vehicles (3).
`Before examining in detail the optimum control strat-
`egy for the drivetrain, Section 2 defines the hybrid
`arrangement under study. A description of the opti-
`mization process using an appropriate cost function is
`then presented in Section 3 followed by a method of
`translating the resulting control structure into a sub-
`optimum algorithm capable of being implemented in
`real time. Using the optimum control structure the
`effect of component ratings on the vehicle’s performance
`is evaluated in Section 4, while Section 5 discusses the
`practical implementation of an overall vehicle control
`algorithm. Finally, in Section 6, an indication of the
`vehicle’s potential for substituting petroleum fuel by
`electricity is given.
`Proc Instn Mech Engrs Vol 202 No D1
`
`Page 3 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`@ IMechE 1988
`
`FORD EXHIBIT 1105
`
`

`

`53
`A HYBRID INTERNAL COMBUSTION ENGINEIBATTERY ELECTRIC PASSENGER CAR
`Table 1 Base vehicle data
`severe discharge condition on the battery during hard
`acceleration at high speed. However, during normal
`Parallel hybrid
`operation battery discharge rates are substantially
`reduced and are within acceptable bounds.
`
`Conventional
`
`1640 kg
`1900 kg
`
`950 kg
`1200 kg
`
`0.35
`0.01
`1.95 m 2
`
`0.35
`0.01
`1.95 m2
`
`3 CONTROL OF THE HYBRID ELECTRIC
`DRIVETRAIN
`
`55 kW, 5000 r/min
`-
`
`3.1 General
`
`35 kW, 5000 r/min
`35 kW, shunt
`lead-acid EV2- 13
`E, = 150 kJ/kg
`(42 W-h/kg)
`wt = 300 kg
`3.5 : 1
`4 speed automatic
`gear ratios
`1st 3.5 : 1
`2nd 2.4 : 1
`3rd 1.3 : 1
`4th 1.0: 1
`
`14 s
`
`130 km/h
`145 km/h
`
`3.5 : 1
`4 speed manual
`
`3.5 : 1
`2.4 : 1
`1.3 : 1
`1.0: 1
`
`12 s
`
`145 km/h*
`
`Vehicle weights:
`kerb weight
`test weight
`Vehicle parameters:
`
`CR
`A
`Component sizes:
`i.c. engine
`traction motor
`battery
`
`final drive
`transmission
`
`Performance:
`0-60 mile/h
`(driver only)
`Maximum speed :
`i.c. engine only
`hybrid
`* at 5000 r.p.rn.
`
`With the hybrid arrangement shown in Fig. 1 it is pos-
`sible to operate the drive in a number of different ways,
`or modes. As the use of these different operating modes
`is fundamental to the operation and control of the
`hybrid drive it is important to clearly define what these
`modes are. This is done in Table 2. Although it is clear
`that the regenerative braking mode should be used to
`recover vehicle kinetic energy during braking, how the
`other modes should be utilized is much less obvious.
`This statement is particularly true of the hybrid mode
`when both the i.c. engine and electric traction motor
`drive the road wheels together. The picture is further
`complicated as the battery charge mode, the primary i.c.
`engine mode and the primary electric mode are all
`essentially hybrid modes. However, they differ from the
`true hybrid mode in that one or other of the two prime
`movers is the principal power source and is only aug-
`mented by the other when it, the principal source, is
`unable to provide the requested output torque. In con-
`trast in the true hybrid mode either one of the two
`prime movers is capable of providing all the necessary
`torque but to improve drivetrain efficiency the load is
`shared in some way between the two prime movers.
`How the load should be shared, or indeed if this mode
`should be used at all, is unclear.
`
`a Combined maximum torque line
`b Traction motor torque
`c Engine full-throttle torque
`A Constant-speed road load
`
`modified so as to maintain an acceleration performance
`and level road speed similar to those values defined in
`Table 1.
`The battery system selected for use in the base hybrid
`vehicle is a high-performance lead-acid battery. In any
`hybrid electric vehicle a major limitation in sizing the
`battery is the allowable maximum discharge power
`density the battery can withstand. The selection of a
`300 kg Iead-acid battery for the base vehicle imposes a
`
`250 r
`
`-
`
`200
`
`150
`
`501
`
`100 I-
`
`\
`\
`\
`
`I- /.=
`
`I50 km/h
`
`0 1
`
`I
`1000
`
`I
`2000
`
`I
`3000
`
`I
`4000
`
`I
`5000
`
`Engine speed
`rlmin
`Fig. 2 Base hybrid electric vehicle performance curves
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`Proc Instn Mech Engrs Vol 202 No D1
`
`FORD EXHIBIT 1105
`
`@ IMechE 1988
`
`Page 4 of 15
`
`

`

`54
`
`I FORSTER AND J R BUMBY
`
`i.c. engine mode
`
`Primary electric mode
`
`Primary i.c. engine mode
`
`Table 2 Possible operating modes
`Mode
`Description
`All propulsion power supplied by the
`Electric mode
`electric traction system
`All propulsion power supplied by the
`i.c. engine
`The electric traction system provides
`the principal torque but when
`necessary its maximum torque is
`augmented by the i.c. engine
`The i.c. engine provides the principal
`torque but when necessary its
`maximum torque is augmented by
`the electric traction system
`Both the i.c. engine and the electric
`traction system together, in some
`way, provide the propulsion power
`The i.c. engine provides both the
`propulsion power and power to
`charge the batteries with the traction
`motor acting as a generator
`During braking the vehicle kinetic
`energy is returned to the battery with
`the traction motor acting as a
`generator
`Essentially a primary i.c. engine mode
`when increased torque is provided
`to give acceleration
`
`Hybrid mode
`
`Battery charge mode
`
`Regenerative braking
`
`Accelerator 'kick-down'
`
`/
`
`Acceleration
`
`\"' rake
`
`Parameter
`
`A
`
`Driving cycle
`B
`C
`
`D
`
`Maximum speed
`Vc (mileih)
`Acceleration time
`f a 6)
`Cruise time
`1, (s)
`Coast time
`t,, 6)
`Brake time
`f b (s)
`Idle time
`t , 6)
`Total time
`fs)
`
`102 I
`
`2 0 2
`
`30 '.
`
`45 5 1
`
`4 a l
`
`192
`
`0
`
`1 9 2
`
`18 2
`
`20 2
`
`2 2 1
`
`4 2
`
`8 2
`
`28 2 2
`
`50 2 2
`
`I02 I
`
`3 - t l
`
`5 ? 1
`
`9 2 1
`
`9'. 1
`
`3 0 5 2
`
`2 5 ? 3
`
`2 5 2 2
`
`2 5 k 2
`
`3 9 2 2
`
`7 2 2 2
`
`8 0 2 2
`
`12222
`
`Fig. 4 5227 schedule 'a' series of driving cycles
`
`and to provide any vehicle acceleration, is determined
`at discrete (typically one second) intervals. Over each
`discrete time interval the power and speed are assumed
`to be constant. These values are then reflected back
`through the drivetrain to the on-board energy sources.
`At each drivetrain component full account is taken of
`efficiency, which may vary with both torque and speed,
`so that the calculated energy consumed accounts for
`both the road load requirement and the system losses.
`At each time interval the optimization process com-
`putes the energy consumptions E l and E , associated
`with every possible combination of gear ratio and
`torque split. For a predefined set of weighting factors,
`L , and L, , a three-dimensional surface is therefore
`obtained with the objective function as the dependent
`
`3.2 Optimum control of the hybrid electric drivetrain
`In order to examine the hybrid control problem an
`optimization process has been developed whereby, for a
`given power and speed demand at the road wheels, that
`transmission ratio and torque split between the two
`prime movers which minimizes an objective function
`F(gr9 X) = L,E,(gr> XI + L, E,(gr, X)
`(1)
`is found. In this expression El and E , are the energy
`inputs to the i.c. engine and the electric traction system
`respectively, while L , and L, are weighting factors that
`allow total energy use to be biased towards one or
`other of the two on-board energy sources. The gear
`ratio gr and the torque split ratio x are two, indepen-
`dent, control variables that can be varied to minimize
`the objective function F(gr, x).
`To implement this optimization process over an
`urban driving cycle such as the ECE-15 (Fig. 3) or the
`J227a-D (Fig. 4) the torque required at the road wheels
`to overcome both vehicle drag and rolling resistance,
`
`?"I
`
`Time
`S
`Fig. 3 ECE-15 urban driving cycle
`
`~
`
`Proc Instn Mech Engrs Vol 202 No DI
`
`Page 5 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`0 IMechE 1988
`FORD EXHIBIT 1105
`
`

`

`A HYBRID INTERNAL COMBUSTION ENGINEtBATTERY ELECTRIC PASSENGER CAR
`
`55
`
`a Fuel consumption of the base i.c. engine vehicle
`b 80 km range, 95% of all journeys
`c 50 km range, 90% of all journeys
`d 30 km range, 80% of all journeys
`
`L I ’L2
`Fig. 5 The influence of weighting factor ratio on the performance
`of the base hybrid vehicle (ECE-15)
`
`variable and torque split and gear ratio as the two
`control variables. A direct search for the minimum
`value of
`the objective function then identifies the
`optimum combination of gear ratio and torque split
`that minimizes the objective function F at that time
`instant. The time interval is then updated and the calcu-
`lation repeated. Such a process leads to a minimum
`control trajectory for the objective function F through
`the cycle. A more detailed explanation of the opti-
`mization process can be found in reference (3).
`When the base hybrid vehicle is simulated over an
`urban driving cycle, for example the ECE-15, with dif-
`ferent ratios of weighting factors, L J L , , the vehicle
`range to battery discharge and the i.c. engine fuel con-
`sumption can be expressed as a function of L J L , as in
`Fig. 5. At low values of L J L , greater emphasis is
`placed upon the i.c. engine while at higher values
`greater emphasis is placed upon the electric traction
`system. Thus, when L J L , = 0 the vehicle would com-
`plete the cycle solely on the i.c. engine while for
`L,/L, % 0 the vehicle would tend to operate as an elec-
`tric vehicle over the same cycle. In between these two
`extremes, hybrid operation occurs and, as L J L ,
`increases, greater emphasis is placed on the electric trac-
`tion system, so that range and fuel consumption
`decrease, with energy from the battery being used to
`substitute petroleum fuel.
`At L,/L, = 0.35-0.4 the range is infinite as no net
`energy is removed from the battery and yet fuel con-
`sumption is reduced relative to the ic. engine-only
`extreme. In this condition the energy recovered by the
`electric traction system during braking is used during
`the acceleration phase of the vehicle after accounting for
`system losses. This results in an increase in the average
`it. engine efficiency and a corresponding reduction in
`fuel consumption. This point also corresponds to the
`condition of minimum energy use (3). In this condition
`
`the hybrid vehicle can be described as operating in the
`‘energy-saving’ hybrid mode.
`Analysis of the UK Travel Survey Data (10) shows
`that 95 per cent of all journey lengths are under 80 km
`and, although this urban range cannot be achieved by
`the base hybrid vehicle when in its all-electric mode, it
`would satisfy 90 per cent of all journeys. This implies
`that the vehicle could undertake most urban journeys
`in an electric mode leaving the hybrid mode, with
`0.4 < L,/L2 < 1.0, for longer urban journeys and the i.c.
`engine mode for high-speed cruise. Such a control
`scheme has substantial potential for substituting pet-
`roleum fuel by ‘wall plug’ electricity. In the i.c. engine
`mode the fuel consumption of the hybrid at 90 km/h
`would be 5.5 litres/100 km and 7.8 litres/100 km at
`120 km/h.
`Inspection of the i.c. engine usage maps in Fig. 6 for
`two values of L J L , shows that the use of the i.c. engine
`tends to be restricted to an area surrounding the point
`of maximum efficiency, the size of which depends upon
`the emphasis placed on this particular power source.
`This implies that the operation of the i.c. engine tends
`to be the dominant factor in determining the drivetrain
`control. It should be noted that the optimization
`process is constrained in that i.c. engine clutch slip is
`not allowed such that the electric traction system is
`used to move the vehicle from rest. This operating pro-
`cedure results in efficient operation of the i.c. engine and
`simplifies the drivetrain control in that no automated
`clutch control is necessary. To further improve driveline
`efficiency the i.c. engine is assumed to be switched off
`and decoupled from the driveline when not in use. The
`traction motor is permanently connected to the drive-
`line to ensure that regenerative braking capability is
`always immediately available.
`The torque variations experienced by the i.c. engine
`and the electric motor throughout the cycle are shown
`Proc Instn Mech Engrs Vol 202 No D1
`
`Q IMechE 1988
`Page 6 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`FORD EXHIBIT 1105
`
`

`

`56
`
`-
`90
`-
`81
`-
`12
`-
`3 63
`g
`5 4 -
`’ E
`.- 8 2 4 5 -
`-
`Do
`6
`36
`-
`27
`-
`18
`9 -
`01
`0
`
`I
`
`1000
`
`(a) L,IL, = 0.4
`
`d
`
`l
`
`
`
`I FORSTER AND J R BUMBY
`
`701
`
`60
`
`I
`1
`3000
`2000
`Engine speed
`rlmin
`
`I
`
`4000
`
`L
`5000
`
`150
`
`200
`
`L 1
`100
`Time __
`S
`
`(a) Internal combustion engine
`
`100
`
`20
`
`- 20
`
`,% - 630 -
`540 -
`5 450 -
`360 -
`2 7 0 -
`
`U
`
`$
`
`E
`
`8
`
`0
`
`1000
`
`3000
`2000
`Engine speed
`r/min
`
`4000
`
`5000
`
`Fig. 6
`
`0.6
`(b)L,/L,
`Usage data for the i.c. engine for two values of L J L ,
`(ECE-15) (the figures indicate the percentage of the
`cycle time the i.c. engine spent in each area of the fuel
`map)
`in Fig. 7 for the hybrid with L J L , N 0.6. These results
`show that sharing of the load between the two energy
`sources is only resorted to when either alone cannot
`meet the power demand and then it is the primary i.c.
`engine mode that is used. When in this mode the i.c.
`engine torque is limited to about 90 per cent of full-
`throttle output in order to maximize the i.c. engine eff-
`ciency. The true hybrid mode defined in Table 2
`whereby torque is proportioned between the two prime
`movers is never selected and nor is the primary electric
`made. The torque variations also show that with the
`optimization process used here battery charging from
`the i.c. engine is avoided if at all possible due to the low
`overall conversion effciency associated with this route.
`However, on long journeys, should the state of charge
`of the battery become unacceptably low, then battery
`charging from the i.c. engine would be adopted.
`Although Fig. 5 shows that potential exists for the
`hybrid drive in substituting petroleum fuel by ‘wall
`plug’ electricity, the so-called ‘petroleum substitution’
`hybrid, no account has yet been taken of the effect
`variations in the rating of the driveline components may
`have. In addition,
`the optimal control algorithm
`described above uses a direct search method to deter-
`mine the minimum of a discontinuous and highly non-
`Proc Instn Mech Engrs Vol 202 No D1
`
`Time __
`S
`
`(b) Electric motor
`Fig. 7 Torque variations over the ECE-15 urban driving
`cycle for L J L , ‘v 0.6
`
`linear objective function. As a result, a large amount of
`computing time is required, so making implementation
`of the algorithm in real time difficult. However, the i.c.
`engine usage data presented in Fig. 6 suggest that a
`control strategy that seeks to limit the operation of the
`i.c. engine to a specified region of high effciency could
`produce comparable results.
`
`3.3 Sub-optimum control
`To develop a control algorithm that can be implement-
`ed on an actual vehicle a sub-optimal control algorithm
`is postulated that seeks to restrict the operation of the
`i.c. engine to the high-efficiency region. This algorithm
`accepts demand power as its control variable and, by
`sensing road speed, transforms this power to a torque at
`the output of the transmission. Demand power, as far as
`the simulation is concerned, is simply transmission
`output power, but in reality would be driver-demand
`power, expressed as a function of accelerator pedal posi-
`tion. Knowing the fixed transmission ratios available, a
`set of torque and speed values at the torque split point
`can be defined, the number of which will correspond to
`the number of discrete gear ratios available.
`By defining an operating region or ‘box’ around the
`i.c. engine maximum effciency region as shown in Fig. 8
`then a region of acceptable engine performance is
`defined. The control algorithm always seeks to place the
`i.c. engine operating point within the ‘box’ using the
`available transmission ratios. If no points occur in the
`@ IMechE 1988
`
`Page 7 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`FORD EXHIBIT 1105
`
`

`

`A HYBRID INTERNAL COMBUSTION ENGINEjBATTERY ELECTRIC PASSENGER CAR
`
`57
`
`A Electric operation
`B Internal combustion engine operation
`C Hybrid operation
`
`D Operation not allowed A E Reduced sub-optimum region
`
`I
`
`- - - - - \
`
`\
`
`\
`
`\ \
`‘ , Upper torque bound
`
`IS0 k
`I
`
`100
`
`so
`
`O l
`0
`
`I
`I
`I
`I
`( E l
`I
`I
`
`I
`I
`
`I
`1000
`
`
`
`B
`
`D
`
`speed bound
`
`2
`
`I
`4000
`
`Lower
`torque bound
`
`I
`5000
`
`. _
`I
`I
`3000
`2000
`speed
`r/min
`Fig. 8 Sub-optimum control operating regions
`
`box and all points fall below or to the left of the box,
`then the electric mode of operation is selected. If all
`points occur above the box then primary i.c. engine
`operation is selected with the i.c. engine set at about 90
`per cent throttle (to maximize engine efficiency) with the
`electric traction system making up the additional torque
`requirement. Should more than one point occur inside
`the region, then the box is ‘shrunk’ towards the point of
`maximum efficiency and the test repeated.
`During the electric mode of operation a transmission
`ratio is selected that places the traction motion speed
`closest to its ‘break speed’ as it is in this region that
`maximum traction motor efficiency occurs.
`The result of applying such a control algorithm to the
`hybrid drive designed for petroleum substitution is
`shown in Fig. 9 where the i.c. engine fuel usage map and
`the variation in i.c. engine and traction motor torque
`and speed over the cycle are shown. As can be seen, i.c.
`engine usage is successfully restricted to the high-
`efficiency region and is comparable with the usage data
`for the optimally controlled case shown in Fig. 6b. A
`comparison of the i.c. engine and electric motor torques
`with Fig. 7 shows a similar profile but with a reduced
`number of gear changes. This results because the
`optimum algorithm always seeks the minimum of the
`objective function F, and therefore may make rapid
`changes in the operating strategy that are practically
`unacceptable. Such changes are avoided with the sub-
`optimum algorithm, making for a more practical
`control policy.
`
`4 OPTIMIZATION OF THE HYBRID DRIVE
`4.1 The influence of battery size
`To ensure that satisfactory electric mode performance is
`obtained from the hybrid drive, designed for ‘petroleum
`0 IMechE 1988
`
`substitution’, it is necessary that sufficient energy is
`stored on-board the vehicle to give a range of about
`60 km. To achieve acceptable range in electric vehicles
`it is necessary to use a battery that is typically 25-30
`per cent of the gross vehicle weight (GVW). In order to
`understand why this is so it is necessary to consider
`how the power density of a lead-acid traction battery
`varies with energy density, a typical variation of
`which is shown in the Ragonne plots of Fig. 10. This
`figure shows that not only is the maximum energy
`density available relatively low [typically 144162 kJ/kg
`( 4 M 5 W h/kg) for an advanced lead-acid cell] but also
`as the power density discharge increases the available
`energy density decreases. Therefore, in order to improve
`the discharge efficiency of the battery, it is necessary to
`limit the maximum power density excursions of the
`battery by employing a large battery weight. However,
`as the battery weight increases an increasing proportion
`of the battery energy is being used to propel the addi-
`tional battery weight and not the payload, even though
`vehicle range may still be increasing. To quantify how
`well the battery is being utilized the range per kilogram
`of battery weight (the specific range) can be expressed as
`a function of the ratio of battery weight to total vehicle
`weight (the specific battery weight or battery fraction).
`Such a variation is shown in Fig. 11 for the hybrid car
`in the electric mode for several different driving cycles
`and battery types.
`When using a lead-acid battery and simulating the
`hybrid vehicle over
`the ECE-15 urban cycle the
`optimum battery weight for maximum battery uti-
`lization occurs at about 25 per cent of vehicle weight
`while for a constant 90 km/h cruise it increases to about
`30 per cent of vehicle weight. At battery fractions below
`the optimum, power discharges are high, and so limit the
`available energy from the battery while with too large a
`
`Page 8 of 15
`
`Downloaded from
`
`
`
` at WAYNE STATE UNIVERSITY on January 21, 2014pid.sagepub.com
`
`Proc Instn Mech Engrs Vol 202 No D1
`
`FORD EXHIBIT 1105
`
`

`

`-
`
`0'5 2'o
`
`0.5
`
`I FORSTER AND J R BUMBY
`r
`
`I<
`
`C
`
`58
`
`0
`
`1000
`-
`900
`8 0 0 -
`
`7 0 0 -
`-
`
`u1 g,
`h
`600
`8 m
`$ 2 2 5 0 0 -
`C g
`400-
`B
`3 0 0 -
`E
`200-
`
`EV-106
`
`Improved state of the art } Lead acid
`7
`
`EV2- 13
`-
`d Nickel iron
`e Nickel zinc
`
`1
`3.6
`
`J
`
`I
`36
`
`\ \\\ I
`'
`\
`
`I
`360
`
`Energy density
`kJ/kg
`Fig. 10 Ragonne plots for various battery types
`
`charge efficiency is increasing. For a pure electric
`vehicle with a lead-acid battery, typical battery weights
`are 25-30 per cent of the total vehicle weight and are
`close to the maximum utilization as defined by Fig. 11.
`In practice, selected battery fractions may err to the
`right of the maximum to ensure adequate range and
`maintain driver confidence.
`With the hybrid electric vechicle designed particularly
`for petroleum substitution battery utilization can be
`maximized with a battery fraction of 2&25 per cent.
`Choosing a battery fraction slightly below the optimum
`will help to minimize vehicle weight and is acceptable as
`driver confidence from a range point of view is achieved
`
`w
`
`ECE- 15:Ni/Zn
`
`90 km/h:Ni/Fe
`
`0.3.
`
`ECE- I5 : Ni/Fe
`
`90 km/h
`
`0
`
`0.1
`
`0.2
`
`0.3
`
`Battery fraction
`W k g
`Fig. 11 The influence of battery fraction on specific range
`
`0
`
`1
`lo00
`
`1
`
`I
`3000
`2000
`Engine speed
`dmin
`
`I
`4000
`
`1
`5000
`
`(a) Internal combus

This document is available on Docket Alarm but you must sign up to view it.


Or .

Accessing this document will incur an additional charge of $.

After purchase, you can access this document again without charge.

Accept $ Charge
throbber

Still Working On It

This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.

Give it another minute or two to complete, and then try the refresh button.

throbber

A few More Minutes ... Still Working

It can take up to 5 minutes for us to download a document if the court servers are running slowly.

Thank you for your continued patience.

This document could not be displayed.

We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.

Your account does not support viewing this document.

You need a Paid Account to view this document. Click here to change your account type.

Your account does not support viewing this document.

Set your membership status to view this document.

With a Docket Alarm membership, you'll get a whole lot more, including:

  • Up-to-date information for this case.
  • Email alerts whenever there is an update.
  • Full text search for other cases.
  • Get email alerts whenever a new case matches your search.

Become a Member

One Moment Please

The filing “” is large (MB) and is being downloaded.

Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.

Your document is on its way!

If you do not receive the document in five minutes, contact support at support@docketalarm.com.

Sealed Document

We are unable to display this document, it may be under a court ordered seal.

If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.


Access Government Site

We are redirecting you
to a mobile optimized page.





Document Unreadable or Corrupt

Refresh this Document
Go to the Docket

We are unable to display this document.

Refresh this Document
Go to the Docket