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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 23 1310701-5252-IJMME-IJENS © February 2013 IJENS I J E N S Abstract -- This paper proposes mechatronics design of small electric vehicles (SMEV), including Mechatronics design, modeling, simulation and integration of accurate sub-systems and overall system models. the proposed design and models can be used to select, integrate, analyze and validate Mechatronics deign process of SMEV and its sub-systems ; including mechanical system, control system, components and electrical energy, resulting in simplification, acceleration and increasing accuracy of design. The proposed overall system model can be modified to include any control strategy and/or any electric machine (motor), where the motor and its associated driving power circuit and /or controller can be replaced with different motors and/or control strategy. The proposed model intended to be used for research purposes as well as, for the application in educational process. The proposed models were created and verified using MATLAB simulink software . . Index TermMechatronics design, Electric vehicle, Electric Motor, simulink function block model. I. INTRODUCTION Mechatronics systems design is Modern interdisciplinary design procedure; it is a concurrent selection, evaluation, integration, and optimization of the system and all its components as a whole and concurrently, all the design disciplines work in parallel and collaboratively throughout the design and development process to produce an overall optimal design. Mechatronics engineer is expected to design products with synergy and integration toward constrains like higher performance, speed, precision, efficiency, lower costs and functionality, and in order to evaluate concepts generated during the design process, without building and testing each one, the mechatronics engineer, also, must be skilled in the modeling, simulation, analysis, and control of dynamic systems and understand the key issues in hardware implementation. The Electric Vehicle, EV, was invented around middle of 19 th century. An EV uses one or more electric or traction motors for propulsion and can be separated into three groups, based on how and where the electricity is produced; powered from an external power station, e.g. trolleybuses, powered by stored electricity from an off-board generation system e.g. battery electric vehicles and powered by an on-board electrical generator such as an internal combustion engine (a hybrid electric vehicle)[1] the last two groups are shown in Fig. 1. EV can also be categorized into two groups; big and small electric vehicles. In this paper we are most interested in design and control of Small Mechatronics Electric Vehicles, SMEV. Application examples of SMEV include; golf cars, power chairs for the disabled, go-karts, home mobile robots, mobility scooters, sea scooters and tiny quad bikes. A general model that can be used to simplify and accelerate the mechatronics design process of SMEV is desired. This paper suggests such model, we are to develop general mathematical and simulink models that can be applied in mechatronics design of SMEV, considering all dynamics, with corresponding optimal control strategy for desired output response, a general model that can be used to design, select, integrate, test, analyze and control SMEV to achieve desired performance. The EV system consists of two subsystems, the electric motor and the vehicle systems, the main components of the electric vehicle (see Fig.1) are an electric machine as drive system, electrical energy sources, control systems as a central control, and power converter as a device that converts electrical energy source with variable needs of the electric vehicle by switching devices [2]. Meanwhile electric vehicles generally use a battery as its main energy source [3],[4],[5]. But the batteries on electric vehicles have a weakness that has the capacity and service life is limited so that necessary arrangements for charging batteries do not work hard [2].To drive EV system, one electric motor can be used or two electric motor each for each wheel, we will consider the case of one front drive electric motor used. The EV system takes input voltage as electric motor input, and outputs the rotational speed of electric motor or the motion of electric vehicles, electric motors are capable of generating high torque at low speed, can operate efficiently over a greater range of speeds, that is their speeds can be smoothly controlled and in most cases are reversible, also electric motors and their features can be tested and analyzed both by control system design calculation and by MATLAB software, also by using a simple controller e.g. of PIC micro, with corresponding program and drive circuit, the rotation of electric motor, that is the motion of electric vehicles can be controlled easily and smoothly. The electric actuator most used for SMEV are DC motors, therefore, the SMEV motion control is simplified to a DC motor motion control. Controlling the performance of EV, in particular, smooth driving for comfortable riding, is not a simple task, where the design and operation parameters of EV, Mechatronics Design of Small Electric Vehicles; Research and Education Farhan A. Salem 1,2 1 Alpha Center for Engineering Studies and Technology Researches, Amman, Jordan. 2 Mechatronics program,. Dept. of Mechanical Engineering, Faculty of Engineering, Taif University, 888, Taif, Saudi Arabia. Email: [email protected]
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  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 23

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    Abstract-- This paper proposes mechatronics design of small

    electric vehicles (SMEV), including Mechatronics design,

    modeling, simulation and integration of accurate sub-systems

    and overall system models. the proposed design and models can

    be used to select, integrate, analyze and validate Mechatronics

    deign process of SMEV and its sub-systems ; including

    mechanical system, control system, components and electrical

    energy, resulting in simplification, acceleration and increasing

    accuracy of design. The proposed overall system model can be

    modified to include any control strategy and/or any electric

    machine (motor), where the motor and its associated driving

    power circuit and /or controller can be replaced with different

    motors and/or control strategy. The proposed model intended to

    be used for research purposes as well as, for the application in

    educational process. The proposed models were created and

    verified using MATLAB simulink software.

    .

    Index Term Mechatronics design, Electric vehicle, Electric

    Motor, simulink function block model.

    I. INTRODUCTION

    Mechatronics systems design is Modern interdisciplinary

    design procedure; it is a concurrent selection, evaluation,

    integration, and optimization of the system and all its

    components as a whole and concurrently, all the design

    disciplines work in parallel and collaboratively throughout the

    design and development process to produce an overall optimal

    design. Mechatronics engineer is expected to design products

    with synergy and integration toward constrains like higher

    performance, speed, precision, efficiency, lower costs and

    functionality, and in order to evaluate concepts generated

    during the design process, without building and testing each

    one, the mechatronics engineer, also, must be skilled in the

    modeling, simulation, analysis, and control of dynamic systems

    and understand the key issues in hardware implementation.

    The Electric Vehicle, EV, was invented around middle of 19th

    century. An EV uses one or more electric or traction motors for

    propulsion and can be separated into three groups, based on

    how and where the electricity is produced; powered from an

    external power station, e.g. trolleybuses, powered by stored

    electricity from an off-board generation system e.g. battery

    electric vehicles and powered by an on-board electrical

    generator such as an internal combustion engine (a hybrid

    electric vehicle)[1] the last two groups are shown in Fig. 1. EV

    can also be categorized into two groups; big and small electric

    vehicles. In this paper we are most interested in design and

    control of Small Mechatronics Electric Vehicles, SMEV.

    Application examples of SMEV include; golf cars, power chairs

    for the disabled, go-karts, home mobile robots, mobility

    scooters, sea scooters and tiny quad bikes . A general model

    that can be used to simplify and accelerate the mechatronics

    design process of SMEV is desired. This paper suggests such

    model, we are to develop general mathematical and simulink

    models that can be applied in mechatronics design of SMEV,

    considering all dynamics, with corresponding optimal control

    strategy for desired output response, a general model that can

    be used to design, select, integrate, test, analyze and control

    SMEV to achieve desired performance.

    The EV system consists of two subsystems, the electric motor

    and the vehicle systems, the main components of the electric

    vehicle (see Fig.1) are an electric machine as drive system,

    electrical energy sources, control systems as a central control,

    and power converter as a device that converts electrical energy

    source with variable needs of the electric vehicle by switching

    devices [2]. Meanwhile electric vehicles generally use a battery

    as its main energy source [3],[4],[5]. But the batteries on

    electric vehicles have a weakness that has the capacity and

    service life is limited so that necessary arrangements for

    charging batteries do not work hard [2].To drive EV system,

    one electric motor can be used or two electric motor each for

    each wheel, we will consider the case of one front drive electric

    motor used.

    The EV system takes input voltage as electric motor input, and

    outputs the rotational speed of electric motor or the motion of

    electric vehicles, electric motors are capable of generating high

    torque at low speed, can operate efficiently over a greater

    range of speeds, that is their speeds can be smoothly

    controlled and in most cases are reversible, also electric motors

    and their features can be tested and analyzed both by control

    system design calculation and by MATLAB software, also by

    using a simple controller e.g. of PIC micro, with corresponding

    program and drive circuit, the rotation of electric motor, that is

    the motion of electric vehicles can be controlled easily and

    smoothly. The electric actuator most used for SMEV are DC

    motors, therefore, the SMEV motion control is simplified to a

    DC motor motion control. Controlling the performance of EV, in

    particular, smooth driving for comfortable riding, is not a

    simple task, where the design and operation parameters of EV,

    Mechatronics Design of Small Electric Vehicles;

    Research and Education Farhan A. Salem

    1,2

    1 Alpha Center for Engineering Studies and Technology Researches, Amman, Jordan .

    2Mechatronics program,.

    Dept. of Mechanical Engineering, Faculty of Engineering, Taif University, 888, Taif, Saudi Arabia.

    Email: [email protected]

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 24

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    as well as the road condition are always varying, therefore, the

    controller should be designed to make the system robust,

    adaptive and improving the system on both dynamic and

    steady state performances (fast responsive and low-ripple).

    With reference to testing a maximum speed of 23 m/s, (that is

    82.8 km/h) in maximum of 8 seconds, if an electric vehicle

    with total mass m= 900 kg , friction coefficient of 0.19, air

    density of 1.25 kg/m3 and aerodynamic factors of 0.75, the

    surface area of vehicles 1.5 m2, width of 1 m , height of 0.5,

    the gear ratio G, n at 2, wheel radius of 0.3 m, and maximum

    power efficiency of 0.77

    Battery Battery charger

    Mech

    an

    ical

    tran

    smis

    sio

    n

    Electric motorM

    ech

    an

    ical

    co

    up

    lin

    gPower

    converterDriversController

    Tacho

    Fig. 1. (a) Architecture of electric vehicle

    Battery Battery charger

    Me

    ch

    an

    ica

    l

    tra

    nsm

    issio

    n

    Electric motor

    Mech

    an

    ical

    co

    up

    lin

    gPower

    converterDriversController

    Tacho

    Fig. 1. (b)Architecture of electric vehicle

    Battery Battery charger

    Mech

    an

    ical

    tran

    smis

    sio

    n

    Electric motor

    Mech

    an

    ical

    co

    up

    lin

    g

    Gasoline en.

    Power converterDrivers

    Controller

    Fuel tank

    Fig. 1. (c) Architecture of hybrid electric vehicle; Hybrid vehicle

    combines an internal combustion engine and an electric motor.

    II. SMEV SYSTEM MODELING

    The SMEV system consists of two subsystems, the electric

    motor and the vehicle systems; both will be modeled,

    considering all acting forces and parameters, we will couple the

    SMEV platform with the wheel rotational velocity via

    characteristics of the electric motor and surface as well as to

    derive the expressions for the acting forces, to calculate

    required torque and power expressions, that can be used to

    build the simulink model, finally, suggest, design and couple

    control systems.

    II. I ELECTRIC MOTOR MODELING

    The electric vehicle is driven by an electric motor, the SMEV

    motion control is simplified to an electric motor motion control

    that may or not include gear system. In the proposed model,

    for design and control of SMEV motion control, only the motor

    and its associated driving power circuit can be replaced with

    different types of electric motors used, also with different

    electric motors, it is necessary to use different control

    strategies. EV requires that the driving electric machine has a

    wide range of speed regulation. In order to guarantee the

    speed-up time, the electric machine is required to have large

    torque output under low speed and high over-load capability,

    and in order to operate at high speed, the driving motor is

    required to have certain power output at high-speed

    operation[6]. Presently, brushed DC motor, brushless DC

    motor, AC induction motor, permanent magnet synchronous

    motor (PMSM) and switched reluctance motor (SRM) are the

    main types of motors used for electric vehicle driving [11].

    DC machines are characterized by their versatility. By means of

    various combinations of shunt-, series-, and separately-excited

    field windings, they can be designed to display a wide variety

    of volt-ampere or speed-torque characteristics for both

    dynamic and steady-state operation. Because of the ease with

    which they can be controlled, systems of DC machines have

    been frequently used in many applications requiring a wide

    range of motor speeds and a precise output motor control [13,

    14]. The selection of motor for a specific electric vehicle is

    dependent on many factors, such as the intention of the EV,

    correspondingly allowable variation in speed and torque and

    ease of control, etc. The dynamic equations of these motors

    can be derived, mainly based on the Newtons law combined

    with the Kirchoffs law. The fundamental system of

    electromagnetic equations for any electric motor is given by

    [16,17]

    ( ) (1)

    ks

    s s s s

    kR

    s R R b m R

    s s s R

    R R R S

    du R i j

    dt

    du R i j P

    dt

    L i L i

    L i L i

    Where :k the angular speed of rotating coordinate system

    (reference frame), Depending on motor construction (AC or

    DC), the method of the supply and the coordinate system

    (stationary or rotating with the rotor or stator flux) the above

    mentioned model becomes transformed to the desirable

    form[18], and the complement Eqs. (1) is equations describing

    mechanical part of eclectic motor.

    A series wound DC motor has the armature and field coils

    connected in a series across the power source as shown in Fig.

    2(b) A series wound DC motor is easy to use, will generate a

    larger torque increase (startup torque) compared with a shunt

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 25

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    wound DC motor for given increase in current. Series motors

    cannot be used where a relatively constant speed is required

    under conditions of varying load." this means series wound

    DC might not climb hills with varying slope briskly and

    smoothly. The voltage supply is divided between stator and

    rotor circuits and a common current flow through the field and

    armature coils current ia, this all can be expressed as:

    in a fV V V , ,m f ai i i

    Applying Kirchoffs law around the electrical loop,

    ( ) ( )a fin a f a f a adi di

    V s L L I R I R EMFdt dt

    ( ) ( ) * *a fin a f a f a mutual ndi di

    V s L L I R R L idt dt

    Where :Lmutual :is the mutual inductance between the armature

    winding and the field winding . Under steady state condition,

    induction (L=0), gives:

    ( )in f a a aV s R I R I EMF

    ( )in a f aV s I R R EMF The torque developed in the rotor is:

    * * *m f fT K i K i

    2 *m tT K i

    The back EMF, also, can be expressed as:

    * * ( * )b n b f a nEMF K I K K

    Substituting, we have the armature current given by:

    ( )ina

    a f b m

    V sI

    R R K

    And the developed torque given by:

    2

    2

    *in t

    a f t m

    V KT

    R R K

    From this equation, if the input voltage Vin is kept constant, the

    output angular speed is almost inversely proportional to the

    square root of the torque, therefore a high torque is obtained at

    low speed and a low torque is obtained at high speed. The sum

    of the torques must equal zero, we have:

    Te T T - TEMF = 0

    Substituting the following values, gives : 2

    2

    2* 0mutual Load m m

    d dL i T J b

    dtdt

    A shunt wound DC motor has the armature and field (stator)

    coils connected in parallel (or shunt) across the power source,

    in result the same voltage is applied to both coils this is shown

    in Fig. 2(a). Shunt wound DC motor is designed for

    applications where constant speed characteristics under

    varying load conditions are important such as pumping fluids

    and fans, shunt motor speed varies only slightly with changes

    in load. A shunt wound DC difficult to control, as reducing the

    supply voltage also results in a weakened magnetic field, thus

    reducing the back EMF, and tending to increase the speed.

    The stator and rotor circuits have the same voltage supply and

    therefore the same voltage drop, and the current drawn by the

    motor, im is the sum of the field current, if and armature current

    ia, this all can be expressed as:

    in a fV V V , m f ai i i

    The DC shunt motor has the same equations for torque as for

    the separately excited motor,

    A compound wound DC motor is a combination of shunt wound

    and series wound configurations as shown in Fig.2(c). This

    allows the compound motor to be used in applications where

    high starting torque and controlled operating speed are both

    required.

    The separately excited DC motor (Fig.2(d)) The voltage is

    applied to both to field and armature terminals, as shown, there

    are two currents, filed current, if and armature current, ia in

    order to have linear system, one of these two currents most

    held constant, this motor allows having independent control of

    both the magnetic flux and the supply voltage, which allows

    the required torque at any required angular speed to be set

    with great flexibility. The biggest drawback is they are noisy. In

    [12] the mathematical model, transfer function and simulink

    model of separately excited DC motor were derived and built,

    where from Eqs. (1);

    The air-gap flux, is proportional to the field current and

    given by:

    *f fK i 2

    The back EMF voltage is given by:

    3 EMF K* * - Im in a aV R

    The torque developed by the motor is related linearly to air-gap

    flux, and the armature current ia(t), and given by:

    1 * * ( )m aMotor Torque T K i t

    Substituting (2) in (3), and rearranging to separate current ,we

    have:

    1 * * ( )* ( )m f a fT K K i t i t

    1

    ( ) * * ( ) *

    m m

    f

    f a b

    T Ti t

    K K i t K

    4

    Substituting (4) in (3), gives:

    - K* * min m ab

    TV R

    K

    The torque developed, is given by:

    K*

    m in b na

    T V KR

    The transfer function relating input filed voltage Vin_field(s), and

    motor output speed m(s), with armature current ia(t) held

    constant and ,given by:

    _

    ( )( )

    ( )

    m

    angle

    in filed f f

    KsG s

    V s L s R Js b

    , the transfer function relating input armature voltage to output

    motor angular speed, with varying both armature current ia(t)

    and field current if(t ) , and given by:

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 26

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    22

    ( )

    ( )1

    t f

    a f

    armature b fielda a

    a a a f

    K I

    R R bs

    V s K VL J L Js s

    R b R b R R b

    Brushless DC motor (BLDC): The main disadvantages of

    brushed DC motor drawback is that they need a commutator

    and brushes which are subject to wear and require

    maintenance, therefore have low life-span. the rotor (armature)

    is composed of one or more permanent magnets, see Fig.2(f),

    and coils for the stator (field). The rotor, being a permanent

    magnet, simply follows the stator magnetic field around. The

    speed of the motor is controlled by adjusting the frequency of

    the stator power. In the BLDC motor, the electromagnets do

    not move; instead, the permanent magnets rotate and the

    armature remains static. The BLDC motor is actually an AC

    motor. The wires from the windings are electrically connected

    to each other either in delta configuration or WYE ("Y" -

    shaped) configuration (see Fig.2(f))

    The kinetics of the motor can be described as:

    Te T T - TEMF = 0 2

    20e Load m m

    d dT T J b

    dtdt

    The generated electromagnetic torque, Te is given by:

    * * *P a a b b c cee

    n m

    EMF i EMF i EMF iT

    Where : Pe electromagnetic power of the motor, ea, eb, ec : the

    back EMF in each phase . ia, ib, ic stator phase currents. Under

    normal operation, only two phases are in conduction, therefore

    the voltage balance equation, cross the two windings under

    conduction, is given by:

    ( )( ) ww w w w w

    di tV R i t L EMF

    dt

    Induction motor is a type of alternating current motor where

    power is supplied to the rotor by means of electromagnetic

    induction. Stator windings are arranged around the rotor so

    that when energized with a poly-phase supply they create a

    rotating magnetic field pattern which sweeps past the rotor.

    This changing magnetic field pattern induces current in the

    rotor conductors, which interact with the rotating magnetic

    field created by the stator and in effect causes a rotational

    motion on the rotor. It has the advantages such as low-cost,

    high-efficiency, high reliability, maintenance-free, easy for

    cooling and firm structure, etc. making it especially competitive

    in EV driving. Physical Model of 3-phase AC induction Motor

    is shown in Fig.2(h) [6].

    Permanent Magnets DC Motor,( Fig.2(e))

    DC Motor and its features can be tested and analyzed both by

    control system design calculation and by MATLAB software.

    The PMDC motor is an example of electromechanical systems

    with electrical and mechanical components, a simplified

    equivalent representation of PMDC motor's two components

    are shown in Fig.2(g). DC motor is a closed loop system in

    nature, the back EMF introduces a negative feedback signal

    proportional to the motor speed, which enhances the damping

    of the system. In [12] the detailed equations of deriving

    mathematical model of PMDC are introduced, where can get

    differential equation that describes the electrical characteristics

    of PMDC motor, by applying Ohm's law, substituting and

    rearranging, all that gives:

    ( ) ( )( ) ain a a a b

    di t d tV R i t L K

    dt dt

    (Las +Ra) I(s) = Vin(s) - Kb s(s) 5

    And, we can get differential equation that describes the

    mechanical characteristics of PMDC motor, by performing the

    energy balance on the PMDC motor system; the sum of the

    torques must equal zero, we have:

    Te T T - TEMF = 0

    Considering that system dynamics and disturbance torques

    depends on platform shape and dimensions the mechanical DC

    motor part, will have the form:

    Kt *ia = T + T + Tload +Tf

    The coulomb friction can be found at steady state, to be:

    Kt *ia - b* = Tf Simplifying and substituting, we have:

    2

    2* 0t Load m m

    d dK i T J b

    dt dt

    KtI (s) = (Jm s + bm) s (s) 6

    The PMDC motor open loop transfer function without any load

    attached relating the input voltage, Vin(s), to the angular

    velocity, (s), given by:

    ( )

    ( )( )

    tspeed

    in a a m m t b

    KsG s

    V s L s R J s b K K

    2

    ( )( )

    ( ) ( ) ( ) ( )

    tspeed

    in a m a m m a a m t b

    KsG s

    V s L J s R J b L s R b K K

    7

    The geometry of the mechanical part determines the moment of

    inertia, the mobile platform can be considered to be of the

    cuboid or cubic shape, with the inertia calculated as shown

    below, where the total equivalent inertia, Jequiv and total

    equivalent damping, bequiv at the armature of the motor with

    gears attaches, are given by: 2 2

    1 1

    2 2

    3

    12

    equiv m Load equiv m Load

    load

    N Nb b b J J J

    N N

    bhJ

    8

    The equivalent mobile robot system transfer function will be

    given by:

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 27

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    2

    ( ) /( )

    ( ) ( ) ( ) ( )

    robot tspeed

    in a equiv a equiv equiv a a equiv t b

    s K nG s

    V s L J s R J b L s R b K K

    9

    The next open loop transfer function, relating the armature

    input terminal voltage, Vin(s) to the output terminal voltage of

    the tachometer Vtach(s), with most corresponding load torques

    applied are considered, is given by:

    inV s *( )

    ( )

    tach t

    open

    tach a a m m a a b t

    K KG s

    V s L s R J s b L s R T K K

    Where :T the disturbance torque, is all torques including

    coulomb friction, and given by:

    T=Tload+Tf For high accuracy, the inertias of the gears and wheels have to

    be included in the calculations, this value can be obtained from

    literature or calculated using the equations for the inertia of a

    cylinder since the gear has a form of cylinder, this can be

    rewritten as follows: 2

    2 1

    2

    ( )equiv motor gear wheelN

    J J J J mrN

    Permanent magnet synchronous motor (PMSM)

    A permanent magnet synchronous motor is a motor that uses

    permanent magnets to produce the air gap magnetic field rather

    than using electromagnets. Such motors have significant

    advantages, such as high efficiency, small volume, light

    weight, high reliability and maintenance-free, etc., attracting

    the interest of EV industry. The PMSM has a sinusoidal back

    EMF and requires sinusoidal stator currents to produce

    constant torque[6].

    The d-q model of PMSM is shown in Fig.2(i) Voltage equations

    are given by:

    * *dd d d e q qdi

    V R i L L idt

    * *dq q q e d d b mdi

    V R i L L i Kdt

    The equations giving the stator current can be written in the

    following form:

    1

    *d d e q qd

    I V L iL s r

    1

    *q q e d d b mq

    I V L i KL s R

    The electromagnetic torque developed by the motor is given

    by:

    30.5* ( )

    2

    b q

    m d d q q d d

    K IT P L I I L I I

    The simulink model of series wound DC motor, shunt wound

    DC motor, Permanent Magnets armature controlled DC Motors

    are allmostly identical, the differences are in current filed or

    armature applied to both torque and back EMF constants, this

    can be seen by studying simulink models shown in Fig.3, the

    simulink model of the filed current controlled DC motor is

    shown in Fig.3(a), the simulink model of separately excited DC

    motor is shown in Fig..3(b), Equivalent block diagram of

    PMSM is shown in Fig. Fig.3(c) where Ts =Lq/Rs and =Pbm,

    and ea= f = Pbm f [18], the simulink model of PMDC motor

    is shown in Fig. Fig.3 (d)

    Fig. 2. (a) A shunt wound DC motor Fig. 2. (b) Series wound DC motor

    Fig. 2. (c) Compound DC motor Fig. 2. (d) Separately excited DC

    motor

    Fig. 2. (e) PMDC motor Fig. 2. (f) BLDC motor equivalent

    circuit [6]

    mm

    Electromechanical PMDC motor system

    MECHANICAL component of PMDC motor systemELECTRIC component of PMDC motor system

    Fig. 2. (g) Schematic of a simplified equivalent representation of the PMDC

    motor's electromechanical components

    Fig. 2. (h) Model of 3-phase AC

    induction Motor[6]

    Fig. 2. (i) The d-q model of PMSM

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    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    fi led

    current

    motor

    torque

    motor angular

    speed

    Motor linear

    speed

    1

    Lf.s+Rf

    filed

    Transfer Fcn

    1

    J.s+B

    Transfer FcnStep

    12 V

    Scope

    1

    s

    Integrator

    Km

    Gain

    Fig. 3. (a) Simulink model of the filed current controlled DC motor

    fi led current motor torquemotor angular

    speed

    Motor l inear

    speed

    angular

    speed

    armature

    Current,i Motor

    Torque

    Armature

    Field

    current

    the armature current IS maintained constant ia(t) = ia= constant

    SEPARETLY EXCITED DC MOTOR

    Armature

    inductance

    mutual

    inductance

    Table: Parameters of the DC Motor.

    Vf=240[V]

    La=0.012[mH]

    Va=240[V]

    Lmutual=1.8[mH]

    Rf=240[W]

    J=1[Kg.m2]

    Ra=0.6[W]

    Cr=29.2[N.m]

    Lf=120[mH]

    Fc=0.0005[N.m.Sec/Rad]

    -K-

    rad2mps

    V=W*r1

    Km

    motor

    constant

    linear speed

    1/n

    gear ratio

    n=3.1

    fc

    friction

    coefficient

    1

    Lf.s+Rf

    filed

    Transfer Fcn

    1

    Lf.s+Rf

    field

    angular

    speed

    Vin.

    fi led

    Vin

    armature

    V armature

    V Field

    1

    J.s+B

    Transfer Fcn

    motor.mat

    To File..

    Step

    12 V

    Kb

    Scope

    Product1

    Product

    TloadLoad

    torque

    1

    s

    Integrator.,

    1

    s

    Integrator.

    1

    s

    Integrator,

    1

    s

    Integrator

    1/J

    Inertia

    Km

    Gain

    1/Lf

    Field

    inductance.

    Cr

    Couple

    resisting

    -K-

    .1

    .,

    1

    La.s+Ra

    ,.

    1

    Jequiv.s+bequiv

    ,

    -K-

    mutual

    Inductance

    La

    armature

    inductance1/Lf

    Field

    inductance

    Rf

    Field

    resistance

    Ra

    Armature

    resistance

    1/La

    Fig. 3. (b) Simulink model of separately excited DC motor

    Fig. 3. (c) Equivalent block diagram (simulink model) of PMSM

    angular

    speed

    Current,iTorque

    EMF constant

    Kt

    torque

    constant

    -K-

    rad2mps

    V=W*r1linear

    speed

    1/n

    gear ratio

    n=3.1

    Vin

    1

    La.s+Ra

    Transfer function

    1/(Ls+R)1

    1

    Jequiv.s+bequiv

    Transfer function

    1/(Js+b)1

    Motor.mat

    To File..Kb

    TloadLoad

    torque

    Fig. 3. (d) Simulink model of PMDC motor.

    II.II MODELING ELECTRIC VEHICLE, SMEV, DYNAMICS

    When deriving an accurate mathematical model for SMEV, it is

    important to study and analyze dynamics between the road,

    wheel and SMEV considering all the forces applied upon the

    EV system. The modeling of a SMEV system dynamics

    involves the balance among the several acting on a running

    SMEV forces, these acting forces are categorized into road-

    load and tractive force. The road-load force consists of the

    gravitational force, hill-climbing force, rolling resistance of the

    tires and the aerodynamic drag force and the aerodynamics lift

    force, where aerodynamic drag force and rolling resistance is

    pure losses, meanwhile the forces due to climbing resistance

    and acceleration are conservative forces with possibility to,

    partly, recover. This resultant force is the sum of all these

    acting forces, will produce a counteractive torque to the

    driving motor, i.e., the tractive force.

    The disturbance introduced to the EV system is changes in the

    road surface inclination angle, , it is required to design

    controller to be robust and should have a disturbance

    rejection. The disturbance torque to SMEV is the total

    resultant torque generated by the acting forces, and given by:

    aerod rolling climb Linear_acc angular_accF F F FTotalF F 10

    To determine the electric battery capacity, we need to

    estimated energy required of SMEV platform, the requested

    power in kW that SMEV platform must develop at stabilized

    speed can be determined by multiplying the total force with the

    velocity of the SMEV, and given by:

    ( )* *Total TotalP F F 11

    Electrical power (in watts) in a DC circuit can be calculated by:

    P= I x V

    Where: I is current in Amps and V is voltage. Based on

    fundamental principle of dynamics the acceleration of the

    vehicle is given: by

    *

    m totalP P

    M

    Where: Pm :The power available in the wheels of the vehicle.

    M,: vehicle mass and speed

    The total resistive torque, TotalT is the torque of all acting

    forces. The driving force comes from the powertrain shaft

    torque, which can be written as the wheel torque, given by:

    * *wheel shaftT G T 12

    This wheel torque provides the resultant driving, tractive force,

    FTotal to the vehicle:

    * *wheel shaftTotal

    T G TF

    r r

    13

    Referring to Fig.4, the relationship between the resultant

    tractive force and the torque produced by the motor Tshaft ,can

    be obtained as:

    **

    shaft Total

    rT F

    G 14

    The vehicle inertia torque can, also, be defined by the

    following relationship:

    vehicl

    Vehicl

    dT J

    dt

    The relationship between the linear velocity of SMEV platform,

    v, and the angular velocity of the electric motor is given by:

    * /r G Where: r: The tire radius of the mobile platform. G,n: The

    transmission gearing ratio. TL: Tshaft is the torque produced by

    the driving motor. : The transmission efficiency. v: the

    velocity of the vehicle. : the angular velocity of the motor. It

    is required to couple the SMEV platform with the wheel

    rotational velocity via characteristics of the electric motor and

    surface such as the traction force, the torque, etc. as well as to

    derive the expressions for the acting forces, to calculate

    required torque and power expressions that can be used to

    build the simulink models.

    Traction force

    F,wind

    Fgrafitation

    Faerod

    M*g

    Ftractive

    Fwheel_powertrain

    = r

    FLift

    Fig. 4. (a)

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    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    M*g

    Road incl.

    Fig. 4. (b)

    Fig. 4. (a)(b) Forces acting on moving vehicle.

    II.II.I Rolling resistance force, Frolling: is produced by

    flattening of the tire at the contact surface of the roadway and

    depending on the vehicle speed and it is proportional to the

    vehicle weight, and is given by:

    rolling _ r rF *C * *C *cos( )normal forceF M g 15

    For motion on a level surface, =0, cos()=1 , and Eq.(15)

    becomes:

    rolling _ r rF *C * *Cnormal forceF M g

    In terms of the vehicle linear speed Eq.(15) becomes:

    rolling r0 r1F M *g * C -C * * ( )sign Where : M : The mass of the SMEV and cargo (Kg). g .Cr The

    rolling resistance coefficients is calculated by the following

    expression:

    r

    3.6C 0.01 1

    100robot

    The rolling resistance torque is given by:

    rolling rT * *C *cos( ) * rM g r

    II.II.II Aerodynamic Drag force , Faerod: is the force opposing

    the motion of the SMEV due to air drag, the aerodynamic drag

    force is function of mobile platform linear velocity, and given

    by: 2

    aerod dF 0.5* *A*C * vehicl 16

    Considering car and wind speed Eq.(16) become:

    2

    aerod dF 0.5* *A*C * * ( )vehicle wind vehiclesign

    2

    aerod dF 0.5* *A*C * *vehicl wind vehicl windsign

    The aerodynamics torque is given by:

    2

    aerod d

    1T * *A*C * *

    2vehicle rr

    17

    Where: Cd : Aerodynamic drag coefficient characterizing the

    shape of the SMEV and can be calculated using the following

    expression:

    aerod

    2

    F

    0.5DC

    S

    S: frontal area of SMEV, assuming shape of the SMEV is long

    cylinder , Cd =0.80, for sphere Cd =0.47, and for

    streamlined body Cd =0.04 . A: Cross-sectional area of

    the SMEV where it is the widest, (m2) : The linear speed of the

    SMEV (m/s), o : The speed of the wind (m/s), against the

    direction of the SMEV's motion, rr: Rotor winding resistance

    (per phase), rr =0.0503 Ohm. : The air density (kg/m3) at STP,

    =1.25, At 20C and 101 kPa, =1.2041, The air density is

    calculated by Eq. (18) expression, where: o = 101325 Pa, sea

    level standard atmospheric pressure, T0 = 288.15 K sea level

    standard temperature. g = 9.81 m/s2.Earth-surface gravitational

    acceleration. L = 0.0065 K/m temperature lapse rate. R =

    8.31447 J/(mol*K) universal gas constant. M = 0.0289644

    kg/mol molar mass of dry air: *

    *

    0

    ** 1

    *

    g m

    R L

    O

    L hM

    T

    R T

    18

    II.II.III The aerodynamics lift force, Flift; is caused by

    pressure difference between the SMEV's roof and underside,

    and is given by:

    19 20.5* * * *lift L vehicleF C B

    Where: B : SMEV's reference area. CL: The coefficient of lift, (

    CL to be 0.10 or 0.16), and can be calculated using the

    following expression:

    20.5L

    LC

    A

    Where: L: lift, the air density (kg/m3) at STP, =1.25, V:

    velocity of SMEV, A: frontal area.

    II.II.IV The force of wind , Fwind ; can be calculated by:

    2

    wind dF 0.5* *A*C * vehicle wind 20

    II.II.V The hill-climbing resistance force Fclimb; while the

    SMEV is moving up or down a hill, the weight of the SMEV will

    create a hill-climbing resistance force directed downward, this

    force will oppose or contribute to the motion, it is a

    conservative force with possibility to, partly, recover. Two

    components of gravity, the component of gravity in the

    dimension of travel is the hill-climbing resistance force and is

    given by:

    climbF * *sin( )M g 21

    Where: M : The mass of the SMEV and cargo (Kg). g: The

    gravity acceleration (m/s2). :Road or the hill climbing angle,

    road slope (Rad.). If we assume the SMEV is on a level surface,

    this force is zero, 0 = ,sin(0)=0. The hill-climbing resistance, slope, torque, is given by:

    22 climb slopeF F = * *sin( ) * wheelM g r

    II.VI The normal force Fnorm: is the force exerted by the road

    on the mobile SMEV's tires, the magnitude of Fnorm equals the

    magnitude of the Facc in the direction normal to the road, The

    normal force Fnorm can be found as by:

    2norm climbF * *sin( ) 0.5* * * *lift LF F M g C B

    23

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    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    II.VII The linear acceleration force Facc : is the force required

    to increase the speed of the SMEV, The acceleration force is

    the total tractive effort of the SMEV minus the summation of

    forces opposing the motion of the SMEV and can be described

    as a linear motion given by:

    acc 2F * wheel

    Jd dM a M M

    dt dtr

    24

    accF *

    TdM a M M

    dt J

    Where: M : the mass of the SMEV and cargo, a : acceleration

    experienced as a result of the force exerted by the motors or as

    a rotational movement, T: the resultant torque acting on the

    wheels (Nm), J: the total inertia of the SMEV (kgM2), Jwheel : the

    inertia of the wheel (kgM2)

    II.VIII The angular acceleration force Facc_angle , is the force

    required by the wheels to make angular acceleration and is

    given by: 2

    acc_ angle 2F

    wheel

    GJ a

    r 25

    The angular acceleration torque is given by:

    26 2 2

    acc_ angle 2*wheel

    wheel wheel

    G GT r J a J a

    r r

    Substituting derived equations in total force equation, we have

    r0 r1

    2

    d

    Linear_acc 2

    * *sin( ) M *g * C -C * * ( )

    0.5* * A*C * *

    F

    Total

    vehicl wind vehicl wind

    wheel

    F M g sign

    sign

    J dM

    r

    dt

    Based on derived equations, a suggest simulink function block

    model (shown in Fig. 11 that represents SMEV the dynamics,

    and couple the SMEV with the wheel rotational velocity via

    characteristics of the electric motor and surface.

    III. CONTROL SYSTEM SELECTION AND DESIGN

    Electric vehicle speed controller takes the nominally fixed

    voltage from the power source (battery) and outputs a variable

    voltage supply needed to control the motor speed. Its voltage

    output to the drive motors changes in response to control

    signals supplied by the user from foot pedal, [8] When the

    pedal is pushed, the controller delivers electrical currents from

    the battery to the motor; this gives the car acceleration to

    accelerate to the desired output speed, the sensors sense the

    actual output speed and fed it back to controller. the main

    voltage conversion is done very efficiently using PWM

    technique, where controller sends pulses of power to the motor

    thousands of times per second, where very short pulses cause

    the motor to go slowly and long pulses cause the motor to go

    fast. There are many motor control system strategies that may

    be more or less appropriate to a specific type of application

    each has its advantages and disadvantages; the designer must

    select the best one for specific application. In [9], [10]

    The proposed control system composed of two loops, inner

    and outer; The first loop is inner current regulation loop that

    accomplishes current regulation control to meet the current

    needs in accordance with the needs of electric vehicle, and the

    second loop is outer speed regulation loop that adjusts the

    speed of the motor (see Fig. 6).

    PID controllers are ones of most used to achieve the desired

    time-domain behavior of many different types of dynamic

    plants. The sign of the controllers output, will determine the

    direction in which the motor will turn. The PID gains (KP, KI,

    KD) are to be calculated and tuned experimentally to obtain the

    desired overall desired response. The PID controller transfer

    function is given by:

    2

    2

    P ID

    D DI D P IPID P D

    K KK s s

    K KK K s K s KG K K

    s s s

    The transfer function of PID control can be rewritten in terms

    of derivative time and integral time to have the form:

    2 11

    1 I D IPID P D PI I

    T T s T sG K T s K

    T s T s

    Where: IT is the integral time

    P

    I

    K

    K

    and is the derivative time DD

    P

    KT

    K

    PI controller: because of its simplicity and ease of design, PI

    controller is widely used in variable speed applications and

    current regulation of electric motors. The output of the PI

    controller in time domain is defined by the following equation

    (27)

    0( ) ( ) ( )

    t

    C P IV t K e t K e t dt 27 Integrator is added to eliminate the steady state error in the

    control variable. Taking Laplace transforms and manipulating

    Eq. (27) will result in the following transfer function:

    ( ) ( )

    I

    P

    P I P oPI

    current PI P

    KK s

    K s K K s ZKKG s G s K

    s s s s

    ( 1) 1( ) * * 1IPI PI PI

    I I

    T sG s K K

    T s T s

    Where, Vc(t) is the output of the PI controller, KP is the

    proportional gain, KI is the integral gain, and e(t) is the

    instantaneous error signal Zo: zero of the PI-controller KP: the

    proportional gain, KPI: the proportional coefficient; TI: time

    constant. This transfer function, shows that, PI controller

    represents a pole located at the origin and a stable zero placed

    near the pole, at Zo=- KI/ KP, resulting in drastically eliminating

    steady state error due to the fact that the feedback control

    system type is increased by one. The PI pole and zero will

    affect the response, mainly the PI zero, Zo=- KI/ KP, will

    inversely affect the response and should be cancelled by

    prefilter.

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    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    Systems design with prefilter; Prefilter is defined as a transfer

    function Gp(s) that filters the input signal R(s) prior to

    calculating the error signal. Adding a control system to plant,

    will result in the addition of poles and/or zeros, that will effect

    the response, mainly the added zero, will significantly inversely

    effect the response and should be cancelled by prefilter,

    therefore the required prefilter transfer function to cancel the

    zero is given by (28). In general. The prefilter is added for

    systems with lead networks or PI compensators. A prefilter for

    a system with a lag network, mainly, is not , since we expect the

    effect of the zero to be insignificant.

    Pr( ) Oefilter

    O

    ZG s

    s Z

    28

    Controller with deadbeat response design: Deadbeat response

    means the response that proceeds rapidly to the desired level

    and holds at that level with minimal overshoot, The

    characteristics of deadbeat response include; Zero steady

    state error, Fast response, (short rise time and settling time)

    and minimal undershoot, 2% error band[19].

    PI-controller with deadbeat response design: With PI

    controller with deadbeat response design, the overall closed-

    loop transfer function, T(s), will be of third order will and

    contain a zero of the PI-controller, Zo, This zero will

    significantly affect the response of the closed-loop system,

    T(s), and should be eliminated while maintaining the

    proportional gain (KP) of the closed-loop system that can be

    achieved by a prefilter. Thus, the requiring pre-filter transfer

    function [3]:

    Pr( ) PIefilter

    PI

    ZG s

    s Z

    29

    Referring to [19], The controller gains KP and K

    I depend on the

    physical parameters of the system, to determine gains that

    yield optimal deadbeat response, the overall closed loop third

    order transfer function T(s) in terms of Zo and/or KP and K

    I, is

    compared with standard third order transfer function given by

    Eq. (24), and knowing that parameters , and are known

    coefficients of system with deadbeat response given by

    [19],also we choose n based on the desired settling time or

    rise time , this way we obtain the optimal values of Zo and/or

    KP and K

    I , that yield optimal deadbeat response,(for third

    order system =1.9 and =2.2) 3

    tan 3 2 2 3( ) ns dard

    n n n

    G ss s s

    30

    Current controller: The current control loop guarantees

    limited variations of the current trough the inductor during

    important load variations. The current regulation loop is the inner loop connected to the stator circuit; this is shown in

    Fig.5. In this paper we are to suggest to design current

    regulator as PID or PI controller, in order to have small

    overshoot and good tracking performance current regulation

    can be designed as type-I system. In case current controller is

    designed as PI regulator, the parameters of PI current controller

    can be designed as the follows: The motor voltage can be

    written as

    (Las +Ra) I(s) = Vin(s) - Kb s(s) 31

    The Laplace transformed equation of motor stator circuit, in

    terms of input voltage Vin(s) and output current, I(s) is given

    by

    1

    ( ) in b a a

    I s

    V s K s s L s R

    32

    In practical systems, due to the fact that the electromagnetic

    time constant is smaller than electromechanical time constant,

    current regulation is faster than speed regulation. Hence,

    speed regulation is faster than the variation of back EMF,

    therefore, the effect of back EMF on current regulation loop

    can be neglected, therefore (32), can be rewritten as

    1

    in a a

    I s

    V s L s R

    In terms of time constant, motor stator circuit will have the

    form:

    1/

    T s 1

    a

    in electric

    I s R

    V s

    Where : Telectric electrical motor (stator circuit) time constant.

    Depending on [15],[16] , the open loop transfer function of

    current loop is given by:

    _

    1( )

    ( ) (2 1)

    P

    current loop

    a electric s

    KG s

    R T s T s

    The parameters of PI current controller can be deduced

    depending upon generic open loop transfer function with

    damping factor =0.707and given by:

    1( )

    2 ( 1)genericG s

    s s

    4

    a electric P

    P I

    s electric

    R T KK K

    T T

    Therefore, the current regulator transfer function, PI controller,

    is given by:

    _

    _ _

    _

    _ _ _

    ( )

    ( 1) 1( ) * * 1

    I current

    P

    P current I P current

    PI current

    I

    PI current P current P current

    I I

    KK s

    K s K KG s

    s s

    T sG s K K

    T s T s

    Where: KP_current: the proportional gain; KI_current: integral gain;

    TI: time constant of current regulator. mainly the PI zero, Zo=-

    KI/ KP, will inversely affect the response and it could be

    cancelled by prefilter, the required prefilter transfer function to

    cancel the zero is given by:

    Pr1/

    ( )1 /

    o I

    efilter

    o I

    Z TG s

    s Z s T

    33

    Speed regulator controller: The Speed regulation loop is the

    outer loop, this is shown in Fig. 5. In this paper, in order to

    have smooth driving for comfortable riding, no steady state

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 32

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    error and acceptable anti-disturbance capability at transient

    state, we are to suggest designing speed controller as PID or

    PI controller. In case speed controller is designed as PI

    regulator, a PI transfer function given by:

    _

    _

    _ _

    _

    _ _ _

    ( )

    ( 1) 1( ) * * 1

    I

    P

    P I P

    PI speed

    PI speed P P

    KK s

    K s K KG s

    s s

    T sG s K K

    T s T s

    Where, KP_: the proportional coefficient of speed regulator;

    KI_: the integral coefficient of speed regulator; T: time

    constant of motor speed. Depending upon generic open loop

    transfer function, the parameters of speed controller loop can

    be found to be:

    _ _2 4

    P

    P I

    c c

    KJK K

    T T

    Where: Tc is the sum time delay due to speed loop, The same

    approach, with PI prefilter to cancel the zero, can be applied to

    speed loop PI controller.

    The inverter: The input voltage Vin to inverter is considered as

    constant (36V), the main voltage conversion is done very

    efficiently using PWM techniques, the output voltage is

    adjustable via the duty cycle ,of the PWM signal. The

    transfer function of the inverter can be given as in [6] The PI

    current controller is affecting the inverter switching frequency

    to reduce the ripples in the torque and current

    ( )1

    PWM

    converter

    s

    KG s

    T s

    Where: Kpwm: gain of inverter; Ts: time constant of PWM

    controller, (to be 0.25 ms)

    IV. SIMULATION AND RESULTS

    The SMEV subsystems; including the electric motor, the

    vehicle systems and dynamics considering all acting forces

    and control system; all was modeled and coupled, were SMEV

    is coupled with the wheel rotational velocity via characteristics

    of the electric motor and surface and both coupled with control

    systems. The simulink model is shown in Fig. 6. Three control

    strategies are introduced; first strategy controlling both loops;

    current and speed loops with two separate PID controllers for

    each, second strategy, controlling the whole system with one

    PID controller and third strategy controlling both loops;

    current and speed loops with two separate PI controllers for

    each current and speed loop. The simulation of these

    strategies are shown in Fig.7(a)(b)(c), For our design and

    simulation, the desired output max linear speed is to be 23 m/s,

    (that is 82.8 km/h)

    Running simulink model applying two separate PI controllers,

    one for inner current regulation and other for outer speed

    regulation will result in linear speed/time curve shown in Fig. 8

    , adding PI controllers prefilter to simulink block, will eliminate

    the affect of PI zeros on the response, resulting in more

    improved response in the form of smooth driving for

    comfortable riding. Replacing, in Fig Fig.6, both PI controllers,

    for current and speed regulation, with the derived PID

    controllers, defining parameters, running simulink model will

    result in speed curve shown in Fig. Fig. 9,

    Now, Removing PID controller for the current loop, and

    running simulink model with one general PID controller for the

    whole SMEV, and tuning PID gains values, will result in speed

    curve shown in Fig. 10. The obtained response curves show

    that, applying two separate PI controllers , for both inner

    current loop and outer speed loop, will result in more improved

    response in the form of smooth driving for comfortable riding,

    minimum settling time and less power consumption.

    Fig. 6. General Simulink model of SMEV using PI-controller for both,

    inner current and outer speed regulation loops.

    Volt(0:36)

    -K-

    vehicle anglular feedbacK.

    s

    Tw.s+1

    Tw.s

    Speed regulator

    PI Controller

    1/Tw

    s+1/Tw

    Speed loop

    prefilter

    Kb

    S1S

    Manual Switch

    s+1/Ti

    1/Ti

    Current loop

    Prefilter

    1

    Constant11

    Constant

    Add.1Add,

    Kpw

    ,.

    Fig. 7. (a)

    Fig. 7. (b) Two PID controllers for both inner current and outer speed

    regulations loops.

    speed regulator

    PI Controller

    EMF constant Kb

    Speed regulator

    PI controller

    -K-

    vehicle anglular

    feedbacK

    Kpwm

    Ts.s+1

    inverter TF .2

    Kpi*Ti.s+Kpi

    Ti.s

    current regulator

    PI Controller.1

    Kb

    Add.3Add

    Kpw

    .,1

    Kpw

    .

    Tw.s+1

    Tw.s

    -1

    (speed)

    Tw.s+1

    Tw.s

    Fig. 7. (c) PI controllers for both; inner current and outer speed

    regulation loops.

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    Rad/se

    c

    Angular speed/time

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    m2

    Acceleration/time

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    m2

    Acceleration/time

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    Rad/se

    c

    Angular speed/time

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    m2

    Acceleration/time

    0 2 4 6 8-10

    0

    10

    20

    30

    sec

    m2

    Acceleration/time

    Fig. 8. (a) Fig. 8. (b)

    Fig. 8. (a) linear speed/time and (b) acceleration/time responses of SMEV

    using two separate PI controllers for inner current and outer speed loops.

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 33

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    0 5 10-50

    0

    50

    100

    sec (s)

    Rad

    /sec

    Angular speed/time

    0 5 10-10

    0

    10

    20

    30

    sec (s)

    M/s

    Linear speed/time

    0 5 100

    500

    1000

    sec (s)

    Am

    p

    Current/time

    0 5 10-100

    0

    100

    200

    300

    sec (s)

    Nm

    Torque/time

    Fig. 9(a) Fig. 9(b)

    Fig. 9. (a)(b) Two linear speed/time of SMEV response curves using two

    PID controllers for current and speed regulations loops, obtained for

    different values of PID gains.

    0 2 4 6-50

    0

    50

    100

    Time (seconds)

    Rad/s

    ec

    Angular speed/time

    0 2 4 6-10

    0

    10

    20

    30

    Time (seconds)

    M/s

    Linear speed/time

    0 2 4 60

    500

    1000

    1500

    Time (seconds)

    Am

    p

    Current/time

    0 2 4 6-200

    0

    200

    400

    600

    Time (seconds)

    Nm

    Torque/time

    Fig. 10. linear speed/time of SMEV using one PID controller for whole

    SMEV system.

    V. A SUGGESTED FUNCTION BLOCK WITH ITS FUNCTION

    BLOCK WITH IT 'S PARAMETERS WINDOW FOR

    MECHATRONICS SMEV DESIGN, TESTING AND VALIDATING.

    To simplify and accelerate Mechatronics design process of

    SMEV in terms of most mechanical components and control

    system selection and integration, a function block with its

    function block parameters window is proposed, shown in Fig.

    11, , this function block can be used as follows: using

    supporting m.file , designer is to define form, dimensions and

    weight of required SMEV, define required variables and

    coefficients for calculating acting forces e.g. CD, CL A, also

    selected controller and its corresponding gains and/or zeros,

    use manual switch to switch between controller types, PI,PD,

    PI with prefilter, PID for the whole system , one PID for current

    loop and other PID for speed loop, one PI for inner current

    loop and other PD for outer speed loop, finally run the

    suggested model with defined parameters, analyze, evaluate

    and decide.

    VI. FUNCTION BLOCK TESTING AND RESULTS

    Switching the proposed model, to PID control strategy for

    both, inner and outer, loops, defining mechanical system

    parameters, and defining variables and coefficients for

    calculating acting forces, then running model for desired

    output linear speed of 23m/s (82.8 km/h), will return response

    curves shown in Fig. 12, curves show that using PID

    controller for both loops, will result in system response with

    overshoot and allmostly, but not smooth driving for

    comfortable riding, as well as settling time is about 1.4

    seconds.

    Now, making use of simulink PID built-in block capabilities, to

    switch it to PI for inner current loop, and PD for outer speed

    loop , then running model for desired output linear speed of

    23m/s (82.8 km/h), and tuning ,will return response curves

    shown in Fig. 13(a). Now, keeping same arrangement (PI and

    PD controller) but switching input signal to motion profile will

    return response curves shown in Fig. 13(b). Response curves

    show that using PI controller for inner current loop and PD for

    outer speed loop, will result in system response without

    overshoot and in smooth driving for comfortable riding, as well

    as settling time is about 1.8 seconds

    Switching the general model, to PI control with prefilter for

    both , inner and outer, loops, considering that the time

    constants (speed gain Kpw=3.3, speed time constant

    Tw=0.009 , current regulator and current prefilter values Kpi =

    1.51, time constant Ti=0.08, and inverter time constant

    Ts=0.0025, Kpwm=5), Running model for desired output linear

    speed of 23m/s ( 82.8 km/h), will return response curves shown

    in Fig. 14 , settling time is about 5.3 seconds , the performance

    of SMEV is controlled desired response that is with smooth

    driving for comfortable riding,

    The proposed model can be modified, where only the electric

    motor can be replaced with different types of electric motors

    most used for EV, also with different electric motors, it is

    necessary to use different control strategies, model can be

    modified to include PI with dead beat response and IMC

    control.

    0 1 2 3-10

    0

    10

    20

    30

    Seconds (s)

    lin

    . speed M

    Linear speed/time

    0 1 2 3-50

    0

    50

    100

    Seconds (s)

    ang.

    speed R

    ad/s

    ec

    Angular speed/time

    0 1 2 3-50

    0

    50

    100

    150

    Seconds (s)

    Accele

    r. m

    /sec

    2

    linear acceleration m/sec2

    0 1 2 3-500

    0

    500

    1000

    Seconds (s)

    Torq

    ue N

    mTorque/time

    Fig. 12. (a) Linear speed/time, angular speed/time, current/time,

    torque/time, response of SMEV for desired output linear speed of 23

    m/s (that is 82.8 km/h) applying PID control for both inner and outer

    loops

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 34

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    0 2 4 6-10

    0

    10

    20

    30

    Seconds (s)

    lin

    . speed M

    Linear speed/time

    0 2 4 6-50

    0

    50

    100

    Seconds (s)

    R

    ad

    Angular speed/time

    0 2 4 6-10

    0

    10

    20

    Seconds (s)

    m

    linear acceleration m/sec2

    0 2 4 6-100

    0

    100

    200

    300

    Seconds (s)

    Torq

    ue N

    m

    Torque/time

    Fig. 12. (b) Linear speed/time, angular speed/time response,

    current/time, torque/time, of SMEV for desired output linear speed of

    23 m/s (that is 82.8 km/h), applying PID control for both inner and

    outer loops and adding current limiting saturation block (250)

    0 2 4 6-10

    0

    10

    20

    Seconds (s)

    lin

    . speed M

    Linear speed/time

    0 2 4 6-20

    0

    20

    40

    60

    Seconds (s)

    R

    ad

    Angular speed/time

    0 2 4 6-10

    0

    10

    20

    30

    Seconds (s)

    m

    linear acceleration m/sec2

    0 2 4 6-50

    0

    50

    100

    150

    Seconds (s)

    Torq

    ue N

    m

    Torque/time

    Fig. 13. (a) Linear speed/time, angular speed/time Linear

    acceleration/time, current/time, torque/time, response curves of SMEV

    for desired output linear speed of 23 m/s (that is 82.8 km/h), applying

    PD control for outer speed loop and PI for inner current loop .

    0 5 10 15-5

    0

    5

    10

    Seconds (s)

    lin

    . speed M

    Linear speed/time

    0 5 10 15-20

    0

    20

    40

    Seconds (s)

    R

    ad

    Angular speed/time

    0 5 10 15-5

    0

    5

    10

    15

    Seconds (s)

    m

    linear acceleration m/sec2

    0 5 10 15-50

    0

    50

    100

    Seconds (s)

    Torq

    ue N

    m

    Torque/time

    Fig. 13. (b) Linear speed/time, angular speed/time Linear

    acceleration/time, current/time, torque/time, response curves of SMEV

    applying motion profile input and applying PD control for outer speed

    loop and PI for inner current loop .

    0 2 4 6 8-10

    0

    10

    20

    30

    Seconds (s)

    lin

    . speed M

    Linear speed/time

    0 2 4 6 8-50

    0

    50

    100

    Seconds (s)

    R

    ad

    Angular speed/time

    0 2 4 6 8-10

    0

    10

    20

    Seconds (s)

    m

    linear acceleration m/sec2

    0 2 4 6 8-100

    0

    100

    200

    300

    Seconds (s)

    Torq

    ue N

    m

    Torque/time

    Fig. 14. Linear speed/time, angular speed/time Linear

    acceleration/time, torque/time, response curves of SMEV for desired

    output linear speed of 23 m/s (that is 82.8 km/h), applying PI

    controller with prefilter for both , inner and outer, loop

    speed regulator

    PI Controller

    angular

    speed

    Load

    Dynamics

    EMF constant Kb

    input (0:36)

    -K-

    vehicle anglular feedbacK.

    -K-

    rad2mps

    V=W*r1

    linear speed.

    Kpwm

    Ts.s+1

    inverter TF .

    1/n

    gear ratio

    n=3.1

    Kpi*Ti.s+Kpi

    Ti.s

    current regulator

    PI Controller.2

    1

    den(s)

    Transfer function

    1/(Js+b).

    Tw.s+1

    Tw.s

    Speed regulator

    PI Controller

    Kb

    -K-

    Kt.Add.1Add,

    Kpw

    .,1

    -K-

    .

    Tw.s+1

    Tw.s

    -1

    Kpw

    ,.

    1

    La.s+Ra

    ,,

    Fig. 5. SMEV model inner current and outer speed loops.

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 35

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    r/2Rolling resistance force

    M*g*Cr*cos()

    aerodynamics lift force

    r*m/2r*m/2

    angular

    speedTorquecurrent

    Coloum friction

    10

    OUTER LOOP from

    summing d1

    9INNER LOOP from

    summing d3

    8

    OUTER LOOP from summing d2

    7

    OUTER controller output

    6INNER controller

    output5

    linear speed

    in m/s

    4 Current, I

    3

    output anguale speed, Omega

    2T, Torque,

    1Acceleration

    in m/(s^ 2)

    1

    wheel radius,

    V=W*r2

    -K-

    rads2mps=

    R_wheel*(2*pi)/(2*pi).1

    -K-

    r^2m/2. correct2

    0.5

    r*m*g/2 , correct2

    r^2*m*g/1

    d2d1

    Cd

    aerodaynamic torque,

    0.5*p*A*Cd*v^1

    1

    den(s)

    Transfer function

    1/(Js+b).

    sin(u)

    cos(u)

    SinCos.1

    Saturation

    1

    s

    Integrator1

    Divide50

    Divide49Divide48

    Divide47

    Divide46Divide45

    Divide43

    Divide42

    Divide41

    Divide40

    Divide39

    Divide37Divide36

    Divide35Divide34

    Divide33Divide32

    Divide31

    Divide25

    Divide24Divide23

    Divide20Divide19

    Divide1

    Divide,2 du/dt

    Derivative1

    du/dt

    Derivative,1

    Cd

    Cd=0.1

    87

    610

    CL

    .1

    0.5.

    .1

    1,1

    1

    3

    1

    2

    1

    11

    24Inclination angle (0:75)1

    23

    Cr: The roll ing resistance coefficients1

    22P: The invironment ( air) density (kg/m3) 2

    21A:Cross-sectional area of SMEV, where it is the widest, (m2)1

    20Cd : Aerodynamic drag coefficient1

    19

    Kb, EMF constant

    18Current PI Prefilter17Speed PI Prefilter

    16 Inverter

    15B : SMEV underside area1

    14CL: The coefficient of l ift, ( CL to be 0.10 or 0.16)1

    13

    g: The gravity acceleration (m/s2).1

    12

    M : The mass of the mobilr robot 1

    11

    r, wheel radius10Kt, Torque

    constant

    9

    R, Armature Resistance

    8L, Armature

    Inductance

    7 All viscous damping

    6

    Ktac, Tachometer constant , 5

    n, Gear ratio

    4 Inertia motor+ load

    3PI or PID (Inner current)

    2PI or PID (outer speed)

    1

    Vin, Input Volt,(0 :30)

    Fig. 11. (a) SMEV actuator subsystem

    Speed regulator

    PI Controller

    r

    r

    n

    n

    Kpwm

    Ts.s+1

    inverter TF .

    9.8

    g

    Kpi*Ti.s+Kpi

    Ti.s

    current regulator

    PI Controller.

    acceleration

    Torque

    Out1

    Subsystem3

    Out1

    Subsystem1

    Vin, Input Volt,(0 :30)

    PI or PID (outer speed)

    PI or PID (Inner current)

    Inertia motor+ load

    n, Gear ratio

    Ktac, Tachometer constant ,

    All v iscous damping

    L, Armature Inductance

    R, Armature Resistance

    Kt, Torque constant

    r, wheel radius

    M : The mass of the mobilr robot 1

    g: The grav ity acceleration (m/s2).1

    CL: The coef f icient of lif t, ( CL to be 0.10 or 0.16)1

    B : SMEV underside area1

    Inv erter

    Speed PI Pref ilter

    Current PI Pref ilter

    Kb, EMF constant

    Cd : Aerody namic drag coef f icient1

    A:Cross-sectional area of SMEV, where it is the widest, (m2)1

    P: The inv ironment ( air) density (kg/m3) 2

    Cr: The rolling resistance coef f icients1

    Inclination angle (0:75)1

    Acceleration in m/(s 2^)

    T, Torque,

    output anguale speed, Omega

    Current, I

    linear speed in m/s

    INNER controller output

    OUTER controller output

    OUTER LOOP f rom summing d2

    INNER LOOP f rom summing d3

    OUTER LOOP f rom summing d1

    Subsystem

    Step Input Volt(0:36)

    1/Tw

    s+1/Tw

    Speed loop

    prefilter

    Signal 1

    Signal Builder

    P

    Rou, air

    0

    Road slope

    Ramp Input Volt(0:36)

    Ra

    RaPID(s)

    PID current

    PID(s)

    PID speed

    Manual

    Switch

    m

    M

    Linear speed

    La

    La

    Ktach

    Ktach

    Kt

    Kt

    -C-

    Kb, EMF

    s+1/Ti

    1/Ti

    Current loop

    Prefilter

    Current

    Cr

    Cr

    CL

    Cl

    Cd

    Cd

    -C-

    B4

    -C-

    B3

    B

    B

    Angular speed

    A

    A

    Kpw

    .,

    Tw.s+1

    Tw.s

    -

    electic_vehicl4.mat

    ,4

    electic_vehicl3.mat

    ,3

    electic_vehicl2.mat

    ,2

    electic_vehicl1.mat

    ,1

    electic_vehicl5.mat

    ,

    6

    4

    3

    2

    1

    Fig. 11. (b) Function block with its function block with it's parameters window for SMEV design, testing and validating

  • International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 36

    1310701-5252-IJMME-IJENS February 2013 IJENS I J E N S

    VI. CONCLUSION

    Mechatronics design of small electric vehicles (SMEV),

    including Mechatronics design of accurate general models

    and control are proposes, the proposed model can be used

    to select, integrate, analyze and validate, both mechanical

    system with all acting forces and control system, resulting in

    simplification, acceleration and increasing accuracy of

    mechatronics design of SMEV. The proposed model

    intended to be used for research purposes as well as, for the

    application in educational process.

    Testing the models and analysis of resulted response

    curves show that, applying two separate PI controllers with

    corresponding prefilter, for both inner current loop and

    outer speed loop, will result in more improved response in

    the form of smooth driving for comfortable riding of SMEV

    and minimum settling time.

    The proposed model can modified to include any control

    strategy and/or any electric motor, where the motor and its

    associated driving power circuit and /or controller can be

    replaced with different motors and/or control strategy,

    include PI with dead beat response and IMC control. to

    overcome the drawbacks of PI and PID controllers, mainly

    re-tuning process when the operating condition changes

    and motors parameter variations, an m.file can be written to

    calculated the desired values as well as PI-Fuzzy Controller

    can be designed

    REFERENCES

    [1] Asif Faiz, Christopher S. Weaver, Michael P. Walsh, an air pollution from motor vehicles, , standards and technologies for

    controlling emissions, the world bank Washington, D.C. 1996.

    [2] Bambang Sri Kaloko, Soebagio, Mauridhi Hery Purnomo, Design and Development of Small Electric Vehicle using

    MATLAB/Simulink, international Journal of Computer

    Applications (0975 8887) Volume 24 No.6, June 2011

    [3] Dhameja, S., 2002, Electric Vehicle Battery Systems, Newnes, United Stated.

    [4] Husain, I., 2003, Electric and Hybrid Vehicles Design Fundamentals, Pertama, CRC Press, United Stated.

    [5] Larminie, J., Lowry, J., 2003, Electric Vehicle Technology Explained, John Wiley & Son

    [6] Qi Huang, Jian Li and Yong Chen, Control of Electric Vehicle, University of Electronic Science and Technology of China

    P.R.China.

    [7] A. Shekeena1, P. V. R. L. Narasimham, Hybrid control of brushless DC motor for variable speed application, International

    Journal of Computer Science and Management Research, Vol 1

    Issue 3 October 2012

    [8] http://buggies.builtforfun.co.uk/FactFiles/controller.html

    [9] Farhan A. Salem, Ahmad A. Mahfouz, Modeling and controller design for PMDC motor, using different control strategies and

    verification using MATLAB/Simulink , Submitted and accepeted

    but not puplished yet to I.J. Intelligent Systems and

    Applications, Submission ID 124 , 2012

    [10] Hedaya Alasooly, ''Control of DC motor using different control strategies'' global journal of technology and optimization 2011

    [11] Chan, C.C. (1999). The Past Present and Future of Electric Vehicle Development. IEEE Power Electronics and Drive

    Systems,1999, pp.11-13

    [12] Ahmad A. Mahfouz, Mohammed M. K, Farhan A. Salem Modeling, simulation and dynamics analysis issues of electric

    motor, for mechatronics applications, using different

    approaches and verification by MATLAB/Simulink (I).

    Submitted and accepeted but not puplished yet to I.J. Intelligent

    Systems and Applications, Submission ID 123 , 2012.

    [13] Halila A., tude des machines courant continu, MS Thesis, University of LAVAL, (Text in French), May 2001.

    [14] Capolino G. A., Cirrincione G., Cirrincione M., Henao H., Grisel R., Digital signal processing for electrical machines,

    International Conference on Electrical Machines and Power

    Electronics, Kusadasi (Turkey), pp.211-219, 2001.

    [15] Hamdy Mohamed Soliman, S.M.EL. Hakim Improved Hysteresis Current Controller to Drive Permanent Magnet Synchronous

    Motors through the Field Oriented Control International Journal

    of Soft Computing and Engineering (IJSCE) ISSN: 2231-2307,

    Volume-2, Issue-4, September 2012.

    [16] M.P.Kazmierkowski, H.Tunia "Automatic Control of Converter-Fed Drives", Warszawa 1994

    [17] R.D. Doncker, D.W.J. Pulle, and A. Veltman. Advanced Electri-cal Drives: Analysis, Modeling, Control. Springer, 2011.

    [18] Grzegorz SIEKLUCKI,Analysis of the Transfer-Function Models of Electric Drives with Controlled Voltage Source

    PRZEGL AD ELEKTROTECHNICZNY (Electrical Review),

    ISSN 0033-2097, R.88NR7a/2012

    [19] Richard C. Dorf and Robert H. Bishop. Modern Control Systems. Ninth Edition, Prentice-Hall Inc., New Jersey, 2001.

    Authors Profile:ta

    Farhan Atallah Salem : B.Sc., M.Sc

    and Ph.D., in Mechatronics of

    production systems, Moscow state

    Academy. He is author and co-author of

    textbooks and scientific papers in

    Refereed Journals. Now he is ass.

    Professor in Taif University,

    Mechatronics program, Dept. of

    Mechanical Engineering and gen-

    director of alpha center for engineering

    studies and technology researches.

    Research Interests; Design, modeling

    and analysis of primary Mechatronics Machines, Control selection,

    design and analysis for Mechatronics systems. Rotor Dynamics and

    Design for Mechatronics applications