Lecture 13 - Concept of Drive Cycle - 1

00:31:09
https://www.youtube.com/watch?v=ftWx0mE3ivE

摘要

TLDRCette vidéo aborde plusieurs aspects essentiels relatifs à l'usage de l'énergie dans les véhicules électriques. D'une part, elle met en lumière l'importance de disposer de suffisamment d'énergie pour garantir le déplacement efficace du véhicule, en illustrant que l'énergie joue un rôle semblable à celui du carburant. Les calculs de puissance, de vitesse, de force et d'énergie sont cruciaux dans la conception des moteurs, des contrôleurs et des batteries. La vidéo souligne l'importance de choisir la bonne tension pour affecter le courant et, ainsi, minimiser les pertes d'énergie manifestées sous forme de chaleur résiduelle (pertes i²R) dans les conducteurs. Une tension élevée est préférée afin de maintenir un courant plus bas, bien que nécessitant une meilleure isolation pour des raisons de sécurité. Un autre aspect mis en avant est la gestion des pertes de chaleur, lesquelles peuvent affecter la durabilité et l'efficacité des moteurs et batteries, nécessitant parfois des systèmes de refroidissement. Enfin, la vidéo discute des cycles de conduite standardisés, vitaux pour évaluer l'efficacité énergétique de différents véhicules en fonction de leur conception et des conditions de conduite simulées. Des questions liées à la dynamique de la friction, la consommation énergétique sur les pentes et la récupération d'énergie (régénération) sont également abordées.

心得

  • 🔋 L'énergie est essentielle au fonctionnement et à l'autonomie des véhicules.
  • ⚡ La tension et le courant influencent les pertes d'énergie et la sécurité.
  • 🔥 Les pertes de chaleur peuvent affecter les composants du véhicule, nécessitant un refroidissement.
  • 🔄 La régénération permet de récupérer partiellement l'énergie lors des décélérations.
  • 🛠️ La conception du moteur doit prendre en compte la puissance nominale et de pointe.
  • 📏 Les cycles de conduite standardisés évaluent l'efficacité énergétique.
  • ⚙️ Un courant élevé entraîne des pertes thermiques importantes (i²R).
  • 🚗 Une tension élevée réduit le courant et donc les pertes thermiques.
  • ⛰️ L'énergie nécessaire augmente lors des trajets en pente, mais peut être récupérée en partie.
  • 🌡️ La dissipation de chaleur excessive nécessite un système de gestion thermique efficace.

时间轴

  • 00:00:00 - 00:05:00

    L'énergie est cruciale pour permettre à un véhicule de se déplacer comme le carburant pour une voiture. Il faut considérer la conception des moteurs, des contrôleurs et des batteries en fonction de la tension nécessaire, car cela affecte le courant et les pertes de chaleur (pertes par effet Joule I^2R). Une tension élevée réduit le courant nécessaire mais nécessite une isolation pour des raisons de sécurité. La conception doit également tenir compte de la durée de vie de la batterie affectée par des courants élevés.

  • 00:05:00 - 00:10:00

    Les pertes énergétiques dans les systèmes motorisés, telles que les pertes résistives et magnétiques, affectent l'efficacité du véhicule. Le contrôle de la chaleur générée est essentiel pour préserver la batterie, le moteur et le contrôleur. Calculer la puissance de traction et le couple requis selon différents scénarios aide à concevoir un moteur efficace. L'importance du couple de démarrage est soulignée, avec des considérations sur la friction statique et dynamique.

  • 00:10:00 - 00:15:00

    Le couple et la puissance de pointe (utiles pour les manœuvres rapides comme le dépassement) se distinguent du couple et de la puissance nominale qu'un moteur peut maintenir de façon prolongée. Les besoins énergétiques augmentent significativement sur de longues montées, bien que la régénération lors de la descente puisse compenser en partie la consommation énergétique. La capacité d'un véhicule à grimper une pente dépend du couple et de la puissance nominale pour éviter une surchauffe prolongée.

  • 00:15:00 - 00:20:00

    La discussion se poursuit sur les cycles de conduite – comment les caractéristiques du parcours (comme la vitesse, l'accélération, l'arrêt, etc.) influencent la consommation d'énergie en wattheure par kilomètre, un équivalent de l'efficacité énergétique en moteurs à combustion. Un cycle de conduite normalisé permet de comparer les efficacités entre différents véhicules dans des conditions contrôlées.

  • 00:20:00 - 00:25:00

    Un exemple de calcul de consommation énergétique est présenté pour un véhicule roulant à une vitesse constante de 50 km/h en tenant compte de la traînée et de la résistance au roulement. Cela démontre une consommation de 94 wattheure par kilomètre dans des conditions idéales et soulève l'importance du cycle de conduite réel qui inclut des phases d'accélération et de décélération pour une estimation plus précise.

  • 00:25:00 - 00:31:09

    Les exercices proposés visent à calculer les consommations énergétiques pour différents scénarios de conduite, illustrant l'importance de la régénération d'énergie et ses limitations. R comprend tous les types de force dans l'efficacité de régénération, simplifiant les calculs tout en reconnaissant des variations dans la résistance au roulement et la traînée.

显示更多

思维导图

视频问答

  • Pourquoi l'énergie est-elle importante pour un véhicule?

    L'énergie est nécessaire pour permettre au véhicule de se déplacer, déterminant l'autonomie et la distance que le véhicule peut parcourir.

  • Comment le courant électrique est-il impacté par la tension dans un moteur électrique?

    Une tension plus élevée réduit le courant nécessaire à une puissance donnée, minimisant ainsi les pertes par effet Joule (i²R).

  • Qu'est-ce que i²R?

    i²R représente la perte d'énergie (chaleur) dans un conducteur résultant de la résistance électrique lorsque le courant (i) le traverse.

  • Quels problèmes peuvent causer les pertes de chaleur dans un véhicule électrique?

    Les pertes de chaleur peuvent surchauffer le moteur, la batterie et le contrôleur, nécessitant un système de refroidissement pour éviter des dommages.

  • Qu'est-ce qu'un cycle de conduite standard?

    Un cycle de conduite standard définit comment un véhicule est testé dans des conditions simulées pour évaluer sa consommation énergétique.

  • Pourquoi la tension élevée est-elle considérée comme moins sûre?

    Une tension élevée nécessite une isolation complète des composants électriques pour éviter des risques électriques.

  • Comment l'énergie est-elle calculée lors de la conduite sur une pente?

    L'énergie requise augmente à la montée et peut être partiellement récupérée à la descente grâce à la régénération.

  • Qu'est-ce que la régénération dans un véhicule électrique?

    La régénération est la récupération d'énergie lors des phases de décélération ou de descente, réduisant la consommation d'énergie globale.

  • Comment la conception du moteur influence-t-elle les performances du véhicule?

    Un moteur doit être conçu pour gérer la puissance et le couple à la fois nominaux et de pointe, avec un système de dissipation de chaleur approprié.

  • Comment les pertes d'énergie sont-elles minimisées dans les véhicules électriques?

    En concevant des systèmes à haute tension pour réduire le courant, et en utilisant des moteurs et contrôleurs efficaces limitant les pertes thermiques.

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    [Music]
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    [Music]
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    next
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    we are going to talk about energy
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    why is energy important well does the
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    vehicle have enough energy
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    to let the drive take place is like fuel
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    energy is like fuel does it have enough
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    fuel
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    does it store enough fuel
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    it will give you the range that to which
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    you can travel
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    and that becomes an important role and
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    we will talk about energy required
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    another thing that we will come across
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    throughout the course
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    ok with all this known talk power
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    speed force
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    and energy you have to now design motor
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    controller
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    and batteries at what
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    voltage should you design all this
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    you will see that depending on the
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    voltages
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    ah your currents will become very
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    different if you have high voltage
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    your current will go down to give a
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    certain power
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    um after all battery will give you sun
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    power so if you suppose you want a power
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    p
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    if you wanted a voltage v then the
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    current is
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    that power divided by voltage if i want
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    a
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    lower voltage my current will go up
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    if i want higher voltage my current will
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    go smaller
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    normally i prefer lower current
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    why because
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    current i have to carry in conductors
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    and when i carry current in the
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    conductor there is a
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    heat dissipation there is i square r
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    loss
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    now one would say well i square r loss
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    should be small
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    depends on what the current is
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    we will see the currents in some of
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    these vehicles can become 100 ampere
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    200 ampere 300 ampere
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    i square can become very large
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    i therefore do not like this 200 300
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    ampere
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    if i use higher voltage my current may
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    be more like
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    30 ampere 50 ampere 70 ampere 80 ampere
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    much less much easier manageable
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    of course high voltage has another thing
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    lower voltage is safer
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    high voltage is less safe it will
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    require a complete isolation of
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    all the electrical components with the
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    rest of the vehicles
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    finally we will have to see where
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    should we pay the cost of isolation
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    and reduce the currents and where
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    i do not want to get into this isolation
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    let me use low voltage
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    let current go up a little bit so this
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    voltage will be
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    become very important a related
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    thing will be so if i know my peak power
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    requirement what is the current that i
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    will draw
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    what is the average current that i will
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    draw what is the peak power current that
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    will do
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    currents are plays a important role not
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    just in terms of heat loss and
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    conductors but a battery also
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    is normally designed to give you only so
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    much current
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    if you try to draw higher currents from
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    the battery
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    the life of the battery gets impacted
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    we will study that in detail later on in
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    a battery
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    chapter
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    ok so this is another thing that we have
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    to start
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    discussing and then get into details
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    later on
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    and the fourth thing that we will
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    discuss start discussing
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    what are the losses in each subsystem so
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    far we assumed everything is perfect
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    not so motor never runs at 100
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    efficiency
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    you are given a certain amount of power
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    certain amount of energy certain amount
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    of power
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    part of that power is going to get lost
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    into heat it has a double problem
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    problem number one some power and
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    therefore some energy is wasted
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    so i will require more energy to drives
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    the vehicle
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    number two whatever
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    losses are there
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    heat is generated
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    that heat is going to heat up the
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    battery
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    heat up the motor heat up the controller
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    and heat is not good for either the
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    battery
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    or for the motor or for the controller
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    you can allow a certain amount of heat
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    after that you will have to do cooling
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    you have to limit
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    the heat so
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    we have to worry about the losses one is
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    the losses due to i square r
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    but i square r is not the only losses
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    in motor there are other losses
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    and heat is generated so wherever heat
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    is generated we have to worry
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    motors consist of a lot of coils
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    so there is going to be a lot of losses
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    it is not just in simple conductors
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    motor basically is a lossy
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    there are other losses like iron losses
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    you will see in
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    motors so where you worry about this
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    magnetic loss
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    higher losses of magnetic loss
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    so we will start looking at it
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    as we go on we look at more and more
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    all these four things in next section i
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    am going to start with energy
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    that it requires to travel some
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    assignment problems
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    for a two wheeler three wheeler and eric
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    shaw
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    we have shown how to compute traction
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    power
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    torque at different velocity given
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    a certain wheel radius what would be the
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    power and talk required
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    we are basically asking you to learn to
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    compute get some
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    feel of numbers assuming that
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    sedan is stuck on a climb at 12 degrees
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    when it is stuck it has to start
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    and during a start it will require a
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    torque plus i will have to give a
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    minimum acceleration
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    for it to get moving i have taken the
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    very small acceleration
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    0.5 meter per second square so now
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    what do i have to do for that vehicle
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    at zero speed i have to worry about the
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    torque then i have to
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    worry about the acceleration and torque
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    due to acceleration
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    plus there is a drag force i have to
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    worry about the drag
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    ah um acceleration of course with a very
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    zero low velocity so it will be nearly
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    zero
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    there will be some rolling resistance i
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    have to worry about
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    the force due to that and therefore
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    torque due to that
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    so how to combine all these torque and
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    say what is the starting talk required
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    before i start this new chapter there
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    were two questions
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    that were asked to me and let me try to
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    answer
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    the first question was asked is that
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    when a vehicle is starting
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    is mu going to change is there a
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    something called static
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    friction versus dynamic
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    make friction mu is related to friction
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    now there are two ways of dealing with
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    it you can either have a different value
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    of mu
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    mu due to during movement and mu due to
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    starting
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    thats one way of dealing with it
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    very often that is not what is done what
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    is
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    in the vehicle computation what you
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    assume mu is same
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    but you require certain extra
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    acceleration minimal acceleration will
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    require
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    so compute the torque required due to
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    acceleration
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    plus torque required due to the drag
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    mu and that is the dynamic that is
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    during the starting static
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    so in fact in this problem that i talked
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    about
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    in here i have not done it
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    i have done starting but i have to say
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    there is a slope
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    very large slope 12 degrees
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    but i also said include a certain
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    acceleration
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    it is at zero speed but include
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    acceleration
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    so take the acceleration of 0.5 meter
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    per second square you can convert
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    that into ah kilometer
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    whatever any other units now can
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    compute the torque due to this plus
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    compute the torque due to
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    slope that is basically a starting
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    torque which would have otherwise also
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    say mu has changed but we in
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    electric vehicle or even for ic engine
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    vehicle
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    normally mu is assumed to be constant of
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    course there is a small function of
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    velocity
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    at high velocity it matters a lot
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    starting
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    starting torque is the same as
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    moving torque plus acceleration
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    required without acceleration fine you
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    cannot move
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    when you are zero speed you have to get
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    to
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    some kilometer per hour that is starting
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    acceleration starting acceleration
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    is another term used for the change in
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    value of mu
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    so that is a question number one which i
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    think this
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    problem when you do you will get an idea
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    will give you more
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    assignment problem note down on
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    something like this there was a second
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    question that
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    was asked and the second question was
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    achilla yeah suppose you have a long
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    slope
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    in many hills the slope is constant and
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    it continue for 2 kilometers
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    is the energy requirement is the power
  • 00:10:59
    requirement all that
  • 00:11:01
    talk requirement what will happen we
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    will actually
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    deal with that to some extent in this
  • 00:11:06
    chapter of concept of drive cycle
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    but let me let me point out
  • 00:11:15
    it is related to motor design and
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    battery design
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    you normally talk about in a motor
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    the power that motor has certain power
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    but it also has something called peak
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    power
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    a motor will be a 5 kilowatt but its
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    peak
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    power may be eight kilowatt
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    the same motor it can drive at eight
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    kilowatt it can drive at five kilowatt
  • 00:11:53
    so what what is the motor kilowatt
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    what is the peak implies actually
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    as far as the mechanical part of the
  • 00:12:02
    motor is concerned or
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    even the electronic part of the motor is
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    concerned it is the same
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    a five kilowatt motor is eight kilowatt
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    motor is actually designed for
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    torque it is a heat dissipation
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    for at five kilowatt the heat
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    dissipation is small
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    or whatever is the heat dissipation it
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    is taken care of
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    by the cooling system eight kilowatt
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    the speed dissipation is going to be
  • 00:12:28
    much higher
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    now that much higher heat dissipation
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    what do you do if it is fifteen twenty
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    second
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    that extra heat dissipation
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    motor temperature will go up and fifteen
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    twenty seconds will pass
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    and now it will cool down so it will be
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    all right
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    if on the other hand you require a
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    constant
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    eight kilowatt then you require a very
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    different kind of heat dissipation
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    system which will
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    take out this p the losses
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    the heat dissipation at eight kilowatt
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    so i will say a peak power
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    is related to that if it is 15 20 second
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    i can handle it
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    the motor is actually designed for the
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    nominal power
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    or rated power you can say because heat
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    dissipation is designed for rated power
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    so that is what and we will this look at
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    this
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    later on the heat dissipation to some
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    extent
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    same thing about the torque peak torque
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    and rated torque
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    ready torque is you can keep on running
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    with that torque and
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    heat dissipation will be something that
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    you will have to keep on
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    removing such that the temperature does
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    not go up
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    if you go to peak torque you will have
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    extra heat
  • 00:13:59
    generated which is all right for a very
  • 00:14:01
    short period of time
  • 00:14:03
    but its not all right if you reply it
  • 00:14:06
    cons constantly now look at
  • 00:14:09
    what does it mean in terms of driving of
  • 00:14:11
    a vehicle
  • 00:14:14
    if i am trying to overtake somebody
  • 00:14:17
    i need 15 20 second extra power and
  • 00:14:20
    extra torque
  • 00:14:22
    because i will i am moving behind i am
  • 00:14:26
    behind
  • 00:14:26
    i will actually move like this this
  • 00:14:28
    vehicle and then move up 15
  • 00:14:30
    20 25 second that's the time
  • 00:14:34
    peak power and peak torque help normally
  • 00:14:36
    i am not driving above
  • 00:14:38
    the rated power so that is fine
  • 00:14:44
    what about in slope and particularly the
  • 00:14:47
    long slope question that was asked
  • 00:14:50
    in a long slope i may actually drive
  • 00:14:53
    that at that slope
  • 00:14:57
    for five minutes
  • 00:15:00
    maybe even longer because i can reduce
  • 00:15:03
    my speed and all those kind of things
  • 00:15:05
    for power
  • 00:15:06
    but for my torque speed does not matter
  • 00:15:10
    so that cannot be done using peak torque
  • 00:15:13
    or peak power
  • 00:15:14
    it has to be done at rated torque and
  • 00:15:16
    rated power so
  • 00:15:20
    you have to look at the motors rated
  • 00:15:22
    power
  • 00:15:24
    and rated torque and you can
  • 00:15:26
    continuously climb the
  • 00:15:27
    slope at the rated torque rated power
  • 00:15:31
    but if you are using the peak torque and
  • 00:15:33
    peak power to try
  • 00:15:34
    to go up then it can be only for a short
  • 00:15:37
    period of time
  • 00:15:40
    all right what about energy required
  • 00:15:44
    which will be dealing in this chapter
  • 00:15:48
    energy required will go up
  • 00:15:51
    if it is a short period of time it will
  • 00:15:54
    go up
  • 00:15:56
    if it is a stage for a long period of
  • 00:15:58
    time energy
  • 00:15:59
    requirement will go up considerably
  • 00:16:02
    because energy is
  • 00:16:04
    integration of power over time
  • 00:16:08
    so sure in a long slope energy
  • 00:16:11
    requirement will go much higher
  • 00:16:15
    but remember that we also talked about a
  • 00:16:16
    concept of regeneration
  • 00:16:21
    so if you are climbing for long
  • 00:16:24
    you require certain amount of energy
  • 00:16:27
    after that you are going to climb down
  • 00:16:31
    to the same extent and if we
  • 00:16:34
    had a regeneration efficiency my energy
  • 00:16:37
    requirement
  • 00:16:38
    will not make any difference
  • 00:16:43
    but to the extent that i do not have 100
  • 00:16:45
    percent regeneration
  • 00:16:46
    efficiency i have to pay the penalty of
  • 00:16:49
    extra energy
  • 00:16:51
    if i am only recovering let us say 30
  • 00:16:53
    percent of the energy during
  • 00:16:56
    going down so 70 percent of that has to
  • 00:16:59
    be
  • 00:16:59
    spent
  • 00:17:02
    all that issue of how much energy will
  • 00:17:05
    be spent
  • 00:17:06
    is exactly this concept of a drive cycle
  • 00:17:10
    and what is a drive cycle
  • 00:17:15
    the question that we are asking in this
  • 00:17:17
    how much energy will vehicle
  • 00:17:20
    take per kilometer
  • 00:17:24
    how much energy will the vehicle take
  • 00:17:27
    during certain drive
  • 00:17:31
    per kilometer energy per kilometer is
  • 00:17:33
    very important
  • 00:17:34
    it is like your fuel efficiency
  • 00:17:41
    amount of petrol consumed per kilometer
  • 00:17:44
    or
  • 00:17:45
    amount of kilometer for one liter of
  • 00:17:47
    petrol
  • 00:17:49
    the kitna it's the same thing
  • 00:17:54
    energy efficiency is defined in terms of
  • 00:17:57
    water per kilometer
  • 00:17:58
    that depends on the vehicle design but
  • 00:18:01
    it does not depend only on the vehicle
  • 00:18:03
    design
  • 00:18:04
    it also depends on how is the vehicle
  • 00:18:07
    travels
  • 00:18:10
    when you do the measurement what is the
  • 00:18:13
    speed at which it travels
  • 00:18:15
    remember that when it travels at higher
  • 00:18:17
    speed you require larger power
  • 00:18:19
    which means larger energy is consumed
  • 00:18:22
    so you cannot talk about energy
  • 00:18:25
    efficiency or water per kilometer at all
  • 00:18:28
    speeds it will be different
  • 00:18:32
    if a vehicle accelerates it consumes
  • 00:18:34
    tremendous amount of power
  • 00:18:37
    so it will depend on how much you
  • 00:18:38
    accelerate
  • 00:18:40
    how much time you are
  • 00:18:44
    just idling not moving at all you are
  • 00:18:47
    stopped on red light
  • 00:18:50
    how well it decelerates
  • 00:18:54
    when it decelerates it gives you back
  • 00:18:55
    some power energy
  • 00:18:58
    but only fracture of energy so at what
  • 00:19:01
    speed you travel
  • 00:19:02
    for how long then what is acceleration
  • 00:19:05
    for how long
  • 00:19:06
    from what velocity to what how much do
  • 00:19:09
    you decelerate
  • 00:19:10
    for how long how much are you idling all
  • 00:19:13
    these things become an
  • 00:19:14
    important component in the amount of
  • 00:19:16
    energy
  • 00:19:18
    consumed therefore how do you now talk
  • 00:19:21
    about water per kilometer
  • 00:19:24
    you can talk about watt hour per
  • 00:19:27
    kilometer
  • 00:19:28
    by defining what is called a drive
  • 00:19:31
    cycle this by the way is done in a
  • 00:19:33
    petrol engine is also going to be done
  • 00:19:35
    for electrical engineering
  • 00:19:38
    it is a standard a drive cycle a
  • 00:19:41
    standard drive cycle
  • 00:19:43
    a drive cycle says a definition of
  • 00:19:46
    how the vehicle is driven
  • 00:19:50
    try to standardize the driving pattern
  • 00:19:54
    vehicles are tested as per standard
  • 00:19:57
    drive cycle
  • 00:19:58
    the standard drive cycle will tell you
  • 00:20:01
    how long did you travel at what speed
  • 00:20:04
    you traveled for how long
  • 00:20:06
    at how much did you accelerate how much
  • 00:20:08
    did you decelerate
  • 00:20:10
    did you wait idle it will define this
  • 00:20:15
    and for a class of vehicle it will
  • 00:20:18
    standardize it
  • 00:20:19
    and that is called a standard drive
  • 00:20:21
    cycle a standard drive cycle for a two
  • 00:20:23
    wheeler
  • 00:20:24
    a standard drive cycle for a three
  • 00:20:25
    wheeler a standard drive cycle for a
  • 00:20:28
    four wheeler
  • 00:20:30
    what is the purpose of this well
  • 00:20:34
    a dry cycle will help you compare
  • 00:20:37
    if you have made a vehicle you have made
  • 00:20:39
    a vehicle similar
  • 00:20:41
    to wheelers and i can compare what is
  • 00:20:43
    the energy efficiency of yours
  • 00:20:45
    we service data phase
  • 00:20:51
    so i will take example
  • 00:20:54
    a sedan which is driven at a constant
  • 00:20:58
    speed
  • 00:21:00
    of 50 kilometer per hour and let's
  • 00:21:03
    assume
  • 00:21:04
    this is the vehicle this is the vehicle
  • 00:21:07
    the vehicle
  • 00:21:08
    sedan it is in page number slide number
  • 00:21:11
    29 here not 28 because i probably added
  • 00:21:14
    a slide here
  • 00:21:15
    um
  • 00:21:18
    area is 2.5 square meter drag is 0.35
  • 00:21:23
    weight is 1200 kg and suppose it is
  • 00:21:26
    driven at a constant speed of 50
  • 00:21:29
    kilometer per hour
  • 00:21:30
    for 5 minutes
  • 00:21:34
    compute the distance travel
  • 00:21:37
    in energy used
  • 00:21:40
    so if i compute the distant travel
  • 00:21:42
    energy used which i will do out here
  • 00:21:45
    the drag is what 150 newton meter
  • 00:21:50
    that's what comes at 50 kilometer per
  • 00:21:53
    hour
  • 00:21:54
    50 kilometer per hour
  • 00:21:57
    drag comes to 50
  • 00:22:02
    150 newtons 150 newtons
  • 00:22:05
    rolling resistance is higher 190 newtons
  • 00:22:08
    at 50 kilometer
  • 00:22:09
    and if i am driving at a constant speed
  • 00:22:11
    and let us assume no slope
  • 00:22:13
    only the drag and the rolling resistance
  • 00:22:16
    has to be taken into account
  • 00:22:18
    so the total force that i have is 340
  • 00:22:20
    newtons
  • 00:22:22
    power consumed is due therefore 340
  • 00:22:24
    newtons
  • 00:22:25
    multiplied by the velocity velocity is
  • 00:22:28
    50 kilometer per hour after
  • 00:22:30
    convert it into ah meters per second by
  • 00:22:33
    dividing by 3.6
  • 00:22:35
    and actually i am consuming 4.72
  • 00:22:39
    kilowatt to overcome this 4.72 kilowatt
  • 00:22:46
    i am consuming throughout
  • 00:22:49
    for five minutes i am consuming five
  • 00:22:51
    force point seven two kilo
  • 00:22:53
    watt what is the energy that i am
  • 00:22:56
    consuming
  • 00:22:56
    4.7 kilo 2 kilowatt for 300 second
  • 00:23:01
    huh this was the veloci the velocity
  • 00:23:05
    300 second but i want to
  • 00:23:08
    um 300 second
  • 00:23:13
    divided by sorry 5 minutes 500 minutes
  • 00:23:17
    is 300 second but actually
  • 00:23:21
    why do i divide by three point thirty
  • 00:23:23
    six hundred
  • 00:23:24
    uh converting into hour
  • 00:23:28
    huh because i want to actually con write
  • 00:23:31
    down
  • 00:23:32
    not in terms of what second but what
  • 00:23:34
    hour
  • 00:23:35
    and if i do this calculation i get
  • 00:23:39
    393 watt hour
  • 00:23:41
    so every i am consuming 393
  • 00:23:45
    watt or if i continue to drive this for
  • 00:23:47
    one hour it will be
  • 00:23:49
    393 watts
  • 00:23:54
    what hour if i consume continue to well
  • 00:23:57
    for 5 minutes i am consuming
  • 00:23:59
    393 watt hour if i continue to drive for
  • 00:24:02
    60 minutes i will consume 12 times this
  • 00:24:06
    what is the distance traveled well 50
  • 00:24:09
    kilometer divided by
  • 00:24:10
    3.6 per meter per second into
  • 00:24:14
    300 seconds that gives me so many meters
  • 00:24:18
    of 4.16 kilometers
  • 00:24:21
    so what is the energy used per kilometer
  • 00:24:26
    so i am consuming 393 watt hour for 4.6
  • 00:24:30
    k
  • 00:24:31
    ah kilometer so per kilometer i am
  • 00:24:34
    consuming
  • 00:24:34
    94 water per kilometer
  • 00:24:38
    so if i am taking a ideal vehicle
  • 00:24:42
    and just overcome drag and rolling
  • 00:24:44
    resistance at 50 kilometer per hour
  • 00:24:48
    i will consume 94 watt hour
  • 00:24:51
    per kilometer
  • 00:24:55
    now is this the energy efficiency of the
  • 00:24:56
    vehicle
  • 00:24:58
    no this is assuming i am travelling
  • 00:25:00
    constant speed at 50 kilo
  • 00:25:02
    meter per hour but what if i accelerate
  • 00:25:05
    or decelerate what if my velocity goes
  • 00:25:07
    to 30 kilometer
  • 00:25:08
    and then 70 kilometer i will consume
  • 00:25:11
    different
  • 00:25:12
    water per kilometer
  • 00:25:16
    so this is a water per kilometer for
  • 00:25:19
    that drive
  • 00:25:22
    for a standard drive it will be
  • 00:25:24
    something else
  • 00:25:25
    and therefore i have to define standard
  • 00:25:28
    drive
  • 00:25:29
    i am giving a assignment problem
  • 00:25:32
    where i change the drive i have taken
  • 00:25:34
    the same
  • 00:25:35
    sedan this time first i am accelerating
  • 00:25:40
    from 0 to 50 kilometer per hour in 20
  • 00:25:43
    seconds
  • 00:25:45
    now when i am is accelerating at 0 to 50
  • 00:25:50
    50 kilometer per hour in 20 second i can
  • 00:25:53
    actually compute
  • 00:25:54
    the power requirement due to
  • 00:25:56
    acceleration and that is coming
  • 00:25:59
    close to 6000 watts
  • 00:26:03
    for 20 seconds then it travels for 50
  • 00:26:07
    kilometer per hour
  • 00:26:08
    for 5 minutes then it decelerates
  • 00:26:12
    to twenty second
  • 00:26:16
    and i say compute the energy required
  • 00:26:19
    assuming
  • 00:26:21
    r equal to one r equal to 1
  • 00:26:24
    100 regeneration what will be the energy
  • 00:26:27
    required
  • 00:26:30
    can someone tell me
  • 00:26:34
    it is exactly the same 393
  • 00:26:39
    watt hour
  • 00:26:43
    why whatever energy i spent during
  • 00:26:48
    climbing during accelerating i am
  • 00:26:51
    recovering that
  • 00:26:52
    during deceleration
  • 00:26:56
    because r is 1 but in reality r is not 1
  • 00:26:59
    let us take r equal to 0.3 now i have to
  • 00:27:02
    actually compute the energy required
  • 00:27:04
    may required during acceleration i have
  • 00:27:07
    to add the acceleration force
  • 00:27:10
    plus the drag force
  • 00:27:14
    plus the
  • 00:27:18
    rolling resistance force compute the
  • 00:27:21
    power required for all these three
  • 00:27:23
    i have to add the power that's the power
  • 00:27:25
    that i will be requiring for
  • 00:27:26
    accelerating
  • 00:27:28
    figure out how much time will i require
  • 00:27:30
    to get to
  • 00:27:31
    20 second in double in 20 seconds i am
  • 00:27:34
    going to get it
  • 00:27:35
    and i compute the energy and then i also
  • 00:27:39
    compute the
  • 00:27:40
    kilometer travel well the previous
  • 00:27:42
    kilometer
  • 00:27:43
    traveled what i had was assumed earlier
  • 00:27:47
    the 4.16 kilometer was on the when i was
  • 00:27:50
    traveling at 50 kilometer
  • 00:27:51
    but during acceleration also i will be
  • 00:27:53
    traveling some some distance
  • 00:27:55
    so i compute that and then divide it i
  • 00:27:58
    will get water per kilometer
  • 00:28:02
    i take a second problem again assignment
  • 00:28:04
    problem
  • 00:28:06
    this time i am travelling starting from
  • 00:28:08
    0 to 25 kilometer for 15 seconds
  • 00:28:11
    travel at 25 kilometer hour for two
  • 00:28:13
    minutes
  • 00:28:15
    and then i speed from 25 kilometer per
  • 00:28:17
    hour to 50 kilometer per hour
  • 00:28:19
    in another 15 seconds travel for four
  • 00:28:23
    minutes
  • 00:28:24
    at 50 kilo per hour and then decelerate
  • 00:28:27
    to
  • 00:28:27
    0 kilometer per hour and 20 kilo seconds
  • 00:28:31
    compute the energy requirement
  • 00:28:36
    so method is same compute also the
  • 00:28:39
    distance traveled compute what is water
  • 00:28:43
    per kilometer these
  • 00:28:46
    problems are somewhat
  • 00:28:50
    not very difficult problem will get you
  • 00:28:53
    used to
  • 00:28:54
    a concept of a drives what is pointed
  • 00:28:57
    out is very little
  • 00:28:58
    correct we have assumed
  • 00:29:01
    he body is assumed that only the
  • 00:29:04
    acceleration force is reversed
  • 00:29:07
    the drag and rolling resistance is not
  • 00:29:10
    reversed
  • 00:29:12
    so ideally only for the acceleration
  • 00:29:14
    force or the gradient force
  • 00:29:16
    you should apply r
  • 00:29:20
    but you know acceleration force and
  • 00:29:23
    gradient force are so much more
  • 00:29:26
    than the
  • 00:29:29
    rolling resistance and drag drag
  • 00:29:33
    that all that is taking into account in
  • 00:29:36
    r itself
  • 00:29:37
    the regeneration efficiency a and
  • 00:29:41
    you do not separate them you just
  • 00:29:44
    compute that
  • 00:29:45
    and just assume the regeneration
  • 00:29:46
    efficiency if it was only for
  • 00:29:48
    acceleration deceleration
  • 00:29:49
    may have been 0.35 due to combined it is
  • 00:29:52
    only 0.3 so
  • 00:29:54
    you just assume that and in reality in
  • 00:29:57
    computation
  • 00:29:58
    r is assumed for all all the energy
  • 00:30:03
    we are assuming that during climbing up
  • 00:30:06
    and climbing down
  • 00:30:07
    net and energy consumed is zero
  • 00:30:11
    so not exactly correct with r equal to
  • 00:30:14
    one
  • 00:30:15
    but if you want you can do this detailed
  • 00:30:17
    calculation
  • 00:30:18
    but that gets into a little bit of
  • 00:30:21
    trouble we just assume that is
  • 00:30:23
    same for our first course we will assume
  • 00:30:27
    it is same
  • 00:30:28
    it is a combined and will not separate
  • 00:30:30
    out
  • 00:30:31
    otherwise things will get complicated
  • 00:30:35
    ok i mean it is just like that is the
  • 00:30:37
    road always same
  • 00:30:39
    is the rolling resistance always same it
  • 00:30:41
    is not
  • 00:30:42
    it will vary we do not take that into
  • 00:30:45
    account
  • 00:30:49
    so we have somewhat simplified
  • 00:30:54
    in reality you will get slightly worse
  • 00:30:55
    result
  • 00:30:57
    and you will say regeneration efficiency
  • 00:30:59
    is lower
  • 00:31:00
    that's fine okay
  • 00:31:04
    [Music]
标签
  • énergie
  • véhicules électriques
  • batteries
  • moteurs
  • pertes de chaleur
  • isolation électrique
  • tension
  • courant
  • régénération
  • efficacité énergétique