Lecture 16 - Drive Cycles and Energy used per km - Part 2

00:34:56
https://www.youtube.com/watch?v=CN0VQOCYa7Q

Summary

TLDRDans cette vidéo, l'accent est mis sur la dynamique des véhicules, en particulier pour les électriques, en se concentrant sur le cycle de conduite modifié de l'Inde, souvent utilisé pour l'évaluation des voitures dans le pays. Ce cycle, qui imite les conditions réelles de conduite impliquant beaucoup d'arrêts et de démarrages, est couramment utilisé pour évaluer l'efficacité énergétique des véhicules électriques. Un point majeur est l'importance du coefficient de traînée et de la résistance au roulement, qui affectent directement l'efficacité énergétique. Les véhicules électriques montrent comment des changements dans la conception et l'aérodynamisme peuvent impacte significativement la consommation d'énergie. De plus, la vidéo explore les exigences en termes de taille de batterie, d'efficacité du moteur, en particulier en ce qui concerne les moteurs à induction et PMSM, et comment ils affectent l'autonomie et les performances du véhicule. Les défis uniques liés à la conception de camions électriques, incluant la gradabilité et les cycles de conduite sur pente, sont également discutés.

Takeaways

  • 🚗 Le cycle de conduite indien modifié est crucial pour évaluer la performance des voitures en Inde.
  • ⏱️ L'arrêt et le démarrage fréquents sont typiques de la conduite urbaine.
  • 🌬️ Un meilleur coefficient de traînée augmente l'efficacité énergétique.
  • ⚡ Les moteurs PMSM offrent une meilleure efficacité que les moteurs à induction à faible vitesse.
  • 🔋 La taille de la batterie doit équilibrer le poids et l'autonomie.
  • 🚛 Les camions électriques doivent gérer les pentes élevées avec efficacité.
  • 📐 Le couple du véhicule est essentiel pour la conception du moteur.
  • 🔧 L'efficacité du moteur affecte directement la consommation d'énergie.
  • 📉 Réduit le coefficient de traînée et le roulement pour maximiser l'efficacité.
  • 🛠️ L'analyse de sensibilité est cruciale pour une conception optimisée.

Timeline

  • 00:00:00 - 00:05:00

    La première partie de la vidéo explique le cycle de conduite indien modifié, un cycle de 20 minutes pour les voitures, standardisé à l'origine pour les véhicules à essence mais utilisé également pour les véhicules électriques. Le cycle inclut des périodes de conduite, d'arrêt, et peut atteindre 90 km/h. Le conférencier illustre l'importance de la résistance au roulement et des coefficients de traînée, et décrit comment ils affectent l'efficacité énergétique en utilisant un exemple avec un véhicule une berline standard.

  • 00:05:00 - 00:10:00

    Le conférencier poursuit en expliquant l'effet de la régénération sur la consommation énergétique des véhicules. Il compare l'efficacité avec et sans régénération et fournit des détails sur les différences de consommation d'énergie. Il met en lumière les inefficacités des différents types de moteurs, comme les moteurs à induction utilisés dans certains véhicules électriques, et les avantages des moteurs PMSM bien conçus en termes d'efficacité à basse vitesse.

  • 00:10:00 - 00:15:00

    Ensuite, l'accent est mis sur l'importance de la conception des véhicules, en insistant sur le besoin de réduire le coefficient de traînée (Cd) pour améliorer l'efficacité énergétique. Les essais ont montré que la résistance de l'air à des vitesses élevées (70-90 km/h) a une influence considérable sur la consommation énergétique. Le conférencier résume que les véhicules consomment le plus d'énergie à des vitesses élevées, contrairement à ce qui se passe à des vitesses plus basses où l’énergie consommée est beaucoup moindre.

  • 00:15:00 - 00:20:00

    La discussion se tourne vers les camions électriques de faible puissance, en évaluant la consommation énergétique et les besoins en couple moteur pour différents scénarios, y compris l'accélération et les montées de pentes. Il est expliqué que, pour ces camions, des considérations supplémentaires doivent être prises en compte pour le couple moteur en raison de leur poids élevé et des exigences de performance en pente. Les résultats montrent que de bons pneus et une faible résistance au roulement sont cruciaux pour l’efficacité énergétique.

  • 00:20:00 - 00:25:00

    Le conférencier résume l'impact des différents paramètres véhicule sur la consommation énergétique et discute également des implications d’un système de transmission à une seule vitesse comparé à des systèmes multivitesse. Il introduit les potentiels avantages et coûts des moteurs distribués par rapport aux moteurs centralisés. Une analyse de sensibilité est réalisée pour montrer l’influence du coefficient de traînée et de la résistance au roulement sur la consommation énergétique.

  • 00:25:00 - 00:34:56

    Enfin, le conférencier présente une vue d'ensemble des chapitres suivants de la série de cours. Il planifie de couvrir les sous-systèmes des véhicules électriques, les fondamentaux des batteries, les moteurs et contrôleurs, ainsi que les infrastructures de charge. La session se termine par un rappel de l'importance de la dynamique du véhicule dans la conception des sous-systèmes EV et invite les étudiants à réaliser les exercices donnés pour une meilleure compréhension.

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Mind Map

Video Q&A

  • Qu'est-ce que le cycle de conduite indien modifié ?

    Le cycle de conduite indien modifié est conçu pour simuler les conditions réelles de la circulation routière en Inde, incluant beaucoup d'arrêts et d'accélérations.

  • Pourquoi le coefficient de traînée est-il important ?

    Le coefficient de traînée influence l'aérodynamisme du véhicule. Un coefficient inférieur signifie moins de résistance à l'air et donc une meilleure efficacité énergétique.

  • Qu'est-ce que la "gradabilité" dans le contexte des camions électriques ?

    La capacité à démarrer et à accélérer sur une pente à un certain degré de pente, crucial pour la performance des camions électriques.

  • Pourquoi un moteur PMSM est-il préféré pour les véhicules électriques ?

    Un moteur synchrone à aimant permanent offre une meilleure efficacité énergétique, surtout à basse vitesse, par rapport à un moteur à induction traditionnel.

  • Quel est l'impact de la taille de la batterie sur le véhicule ?

    Le poids des batteries influence le poids total du véhicule, la consommation d'énergie et l'autonomie du véhicule.

  • Comment le couple est-il calculé pour les véhicules électriques ?

    Le calcul du couple nécessite la prise en compte de la pente et de la vitesse requise, ce qui influence les moteurs et leur efficacité.

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  • 00:00:02
    [Music]
  • 00:00:07
    [Music]
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    ok
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    now let me come to a sediment and
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    this is a very common dry cycle that is
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    used in india
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    called modified indian drive cycle
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    this has been defined by various
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    regulatory agency
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    it is a 20 minutes for cars
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    for cars and it is a modified india
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    drive cycle
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    it was a india drive cycle and then they
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    modified it
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    by looking at actually how the vehicles
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    travel and if you
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    find this one thing again you see that
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    it actually is driving
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    so lot of stop and wait it it drives
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    then stops drives and stops
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    is a very common of the city driving but
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    so this is a city driving this is not
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    highway driving
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    but you also see that occasionally it
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    goes to 70 kilometer
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    and even 90 kilometer per hour so this
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    is a big difference
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    between a four wheeler a four wheeler
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    does when we for example drive on i t
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    highway
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    80 85 kilometer per hour is quite common
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    you
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    also in the evenings and all that you
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    can go to 90 kilometer per hour
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    um and of course highway driving would
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    largely be between 40 and
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    80 90 kilometer that will be a different
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    kind of drive cycle
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    but this drive cycle is also
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    standardized
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    it was actually standardized for a
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    petrol vehicle
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    but we are using the same thing for
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    electric vehicle
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    so once again we can calculate the
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    incremental distance traveled
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    and you find that if you go through at
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    and this is only giving you velocity
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    versus time velocity versus time that's
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    all
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    the drive cycle gives you and from there
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    you have to compute the acceleration
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    you find that integration of the find
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    the distance it travels
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    incremental distance integrated it comes
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    to 10 10.7 kilometer
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    so it's a standard 11 kilometer drive
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    10.7 kilometer
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    you compare one vehicle versus another
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    how much energy does it consume
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    given this you again take a salan
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    we have taken a rough sedan 1400 kg
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    rolling resistance is good you put
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    better tires in the four wheelers
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    drag coefficients 0.4 projected area is
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    close to 2 square meter
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    wheel radius is bigger 0.3 meters
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    again we have assumed regeneration
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    efficiency of 0.5
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    well we will keep changing that and
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    we then as you pointed a vehicle goes up
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    to 90 kilometer
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    so drag coefficient matters a lot
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    projected area matter a lot
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    remember these two parameters play a
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    role and again i calculate
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    what is the energy efficiency first i
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    will just put that in the spreadsheet
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    the numbers the velocity numbers versus
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    every second
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    find the distance traveled five convert
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    into meters per second
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    find the acceleration then find
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    all the three forces
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    acceleration force the rolling
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    resistance force
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    and aerodynamic force i find the total
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    force required
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    from there i compute torque on the one
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    hand i compute power on the other hand
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    integrate it to get the energy and
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    integrate the distance
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    incremental distance to get the total
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    distance
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    and if i find here if i look at this
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    the efficiency is coming to 815
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    815
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    well 815 again i see here the curves
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    showing slightly different
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    i'll check out all these things maybe
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    [Music]
  • 00:04:03
    this is with hundred percent
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    regeneration this is with
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    fifty percent regeneration i think i
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    have taken fifty percent
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    and the peak goes to little bit above
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    eight fifteen actually should have
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    gone to seven fifty but if i take eight
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    hundred and sixteen watt hour
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    and i divided by ten point seven
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    kilometer
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    i only need seventy seven water per
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    kilometer and
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    if i do not take the re with the 100 g
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    regeneration it only consumes 60
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    650 again not correct here but i'll
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    double check these figures
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    fifty or ah watt hour and that comes to
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    sixty point eight
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    um what hour without regeneration
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    consumes ninety one
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    so you can see 90 76
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    60 if i can get regeneration
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    i need much smaller battery between
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    regeneration and without regeneration
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    watt hour per kilometer
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    is 50 percent higher i mean from the
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    100 percent regeneration is 50 percent
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    higher with no regeneration
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    why because you are going up and down
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    increasing the speed and going down
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    thats what you are doing not travelling
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    at constant speed
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    lot of acceleration and deceleration
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    well that gives us what do we need it
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    will give us
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    of course this is not taking into
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    account efficiency efficiencies
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    so you add all of that reality
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    my vehicle consumes closer to 125 watt
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    per kilometer it clearly tells me
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    that there is something not right
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    because i am more or less given the data
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    for my vehicle
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    i do not know whether the tire is that
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    good probably probably not as good
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    but the main difference is in the motor
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    it actually uses an induction motor
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    this is a version one of electric verito
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    it uses a induction motor
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    which at high speed gives me
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    alright efficiency but a lower speed
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    gives me very poor efficiency
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    and since most of the time i am actually
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    travelling at lower speed
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    look at this that's what the city drive
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    does
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    on campus i always travel at lower speed
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    i don't even ever go to 50 kilometer per
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    hour
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    it gives a very poor efficiency and
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    that's the reason
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    on the other hand if you design a good
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    pmsm motor
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    you can get very good efficiency
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    okay this is something that we learn
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    from this
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    the other thing that we will see in a
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    little while
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    is that it is highly dependent on drag
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    drag why because we are going up to 90
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    kilometer per hour
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    drag plays a very important role if c
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    d is reduced efficiency
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    goes down from 76.3
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    or probably i do not remember now
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    whether it was done with 100 0
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    regeneration or
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    fifty percent rejection i will double
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    check that but you can significantly
  • 00:07:19
    reduce that
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    i will show you this number later on
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    again so if i summarize my four wheeler
  • 00:07:24
    most energy consumed between eight
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    hundred second and twelve hundred second
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    in fact that is what you see most of the
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    energies
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    actually energy consumed till 800
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    seconds not very large
  • 00:07:35
    most of the energy is consumed here this
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    now between 800 seconds and 1200 seconds
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    what is happening
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    it is vehicle is going to
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    look at between 800 seconds and 1200
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    second this is a time the vehicle is
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    going up to very high speed 70 and 90
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    kilometer per hour
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    now 70 to 90 kilometer per hour thats a
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    time
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    drag takes over and thats
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    reason most energy is consumed there so
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    if i do not drive that speed
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    i should get very good energy efficiency
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    okay yet eighty water per kilometer to
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    ninety water per kilometer
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    even with an fe fe inefficiency if i can
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    get hundred
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    wattage per kilometer is actually good
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    as i point out motor inefficiencies will
  • 00:08:28
    take into account
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    um as i pointed out if motors are
  • 00:08:32
    designed at for
  • 00:08:32
    higher efficiency sorry higher
  • 00:08:34
    efficiency at higher speeds
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    at lower efficiency it may not be at hm
  • 00:08:39
    lower eye speed it may not have a good
  • 00:08:41
    efficiency and will hurt you a lot
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    that's what actually is happening and
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    typical induction motor
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    based vehicle is giving you 125 watt per
  • 00:08:49
    kilometer
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    because of that so how important it is
  • 00:08:53
    for you to design good vehicle
  • 00:08:58
    the other thing that will become very
  • 00:09:00
    important which you have not done while
  • 00:09:01
    you have calculated torque
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    we have not yet talked about
  • 00:09:07
    how much torque is required and is the
  • 00:09:09
    motor giving me sufficient torque
  • 00:09:11
    we have calculated what the torque is
  • 00:09:12
    required we have not done climbing
  • 00:09:14
    well but even i have shown you how to
  • 00:09:17
    calculate that and in one of the home
  • 00:09:18
    assignment i have told
  • 00:09:19
    you given you that when you climb and go
  • 00:09:23
    down what is the torque
  • 00:09:24
    and energy required
  • 00:09:28
    so the torque needs to be also taken
  • 00:09:30
    into account in designing the motor
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    i will once again now take up one more
  • 00:09:37
    thing
  • 00:09:38
    a low end electric trucks
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    very similar to what we have done except
  • 00:09:46
    the requirements now will change
  • 00:09:49
    fortunately um
  • 00:09:52
    the gvw the gross vehicle weight is very
  • 00:09:55
    high
  • 00:09:56
    you are talking about 3500 kg
  • 00:10:00
    remember that for a four wheeler we took
  • 00:10:02
    1400
  • 00:10:03
    kg that's and this is a low enter this
  • 00:10:06
    is not a high end truck
  • 00:10:08
    with the with the with the material
  • 00:10:11
    rolling resistance is very good i
  • 00:10:12
    deliberately make my
  • 00:10:14
    tire very good i spend money on tire why
  • 00:10:17
    should i waste
  • 00:10:18
    energy drag coefficient well can't do
  • 00:10:21
    much about it
  • 00:10:22
    ah it's a large vehicle so there will be
  • 00:10:25
    lot of drag
  • 00:10:26
    lot of projected area wheel radius is
  • 00:10:30
    made higher
  • 00:10:31
    point four meters i have taken different
  • 00:10:34
    regeneration efficiency
  • 00:10:36
    the vehicle is designed to go up to
  • 00:10:40
    ninety kilometer per hour
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    which is also travels limited extent on
  • 00:10:44
    the
  • 00:10:45
    [Music]
  • 00:10:47
    highway but i have we have taken this mi
  • 00:10:50
    dc
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    cycle the same side cycle that we did
  • 00:10:52
    for four wheelers
  • 00:10:54
    so it will mostly run at lower speed
  • 00:10:57
    once in a while go to the higher speed
  • 00:11:00
    so something that you have seen between
  • 00:11:03
    59 to 89 second
  • 00:11:05
    it travels there is a acceleration
  • 00:11:08
    requirement
  • 00:11:10
    this is something that we had not taken
  • 00:11:12
    ah
  • 00:11:14
    but the accelerated requirement is in
  • 00:11:17
    first 15 seconds it should be able to go
  • 00:11:18
    to 60 kilometer per hour
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    you will see that this does not impact
  • 00:11:23
    the
  • 00:11:24
    power or energy as much it will impact
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    the torque
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    and then from 60 to 90 seconds it should
  • 00:11:32
    be able to go
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    in 25 seconds 60 to 90 kilometer per
  • 00:11:36
    hour
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    kilometer per hour and this is kilometer
  • 00:11:39
    per hour i should have
  • 00:11:40
    added that i'll make the change this is
  • 00:11:42
    a kilometer per hour in 25 seconds
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    there is another very important
  • 00:11:47
    parameter about the
  • 00:11:51
    truck what is the gradability so i have
  • 00:11:54
    taken
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    12 percent it should be able to do at 30
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    kilometer per hour
  • 00:11:59
    now that's again will show will impact
  • 00:12:02
    the torque quite a bit
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    but not just that suppose it is on a
  • 00:12:08
    slope sometime you are traveling on a
  • 00:12:12
    slope say 12 percent
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    but then you need to park so you
  • 00:12:15
    actually move around there is a small
  • 00:12:16
    thing
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    much higher and you go and park there
  • 00:12:22
    now at 20 percent gradient
  • 00:12:26
    it should be able to start
  • 00:12:29
    we are not talking about thirty
  • 00:12:30
    kilometer per hour we are talking about
  • 00:12:33
    zero or one kilometer per hour it not
  • 00:12:36
    only has to start
  • 00:12:37
    but also has to do a little bit of
  • 00:12:39
    acceleration if it does not accelerate
  • 00:12:41
    it will never reach ah never increases
  • 00:12:44
    velocity
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    so small acceleration will take time
  • 00:12:49
    for it to start moving
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    that is additional requirement that we
  • 00:12:55
    have put
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    and we have put auxiliary system load of
  • 00:12:59
    20
  • 00:13:02
    so some of these things will impact the
  • 00:13:05
    torque we haven't done too much
  • 00:13:07
    but the first level come back to this
  • 00:13:09
    vehicle again and again
  • 00:13:11
    this specs this vehicle but what i have
  • 00:13:15
    done
  • 00:13:15
    is i have taken the same mi dc cycle
  • 00:13:18
    same distance of 10.7
  • 00:13:20
    kilometer no slope
  • 00:13:24
    i have not taken slope into account and
  • 00:13:26
    i have actually calculated the energy
  • 00:13:28
    requirement
  • 00:13:32
    and you find that with 30 percentage i
  • 00:13:35
    have done it for 30
  • 00:13:36
    regeneration and i have done it with 100
  • 00:13:39
    regeneration
  • 00:13:40
    at 30 percent regeneration this number
  • 00:13:42
    is right 2603
  • 00:13:44
    watt hour it consumes 10.7 kilometer
  • 00:13:48
    it consumes close to 243 watt per
  • 00:13:51
    kilometer
  • 00:13:55
    this is a much bigger truck and if i
  • 00:13:58
    take
  • 00:13:59
    100 regeneration of course
  • 00:14:03
    it consumes much less it will only be
  • 00:14:06
    slightly above 2000
  • 00:14:09
    watt hour it will consume in 10.7
  • 00:14:11
    kilometer i can calculate it is 191
  • 00:14:14
    watt per kilometer
  • 00:14:19
    i have also calculated the torque and
  • 00:14:22
    that comes from the
  • 00:14:24
    numbers that we saw for 12 percent slope
  • 00:14:29
    at 30 kilometer per hour at 30 kilometer
  • 00:14:32
    i should have written at 30 kilometer
  • 00:14:33
    per hour
  • 00:14:34
    the force required is 4000 newtons
  • 00:14:40
    that number is there in our calculation
  • 00:14:43
    four thousand neutrons
  • 00:14:44
    and torque requirement goes to sixteen
  • 00:14:47
    thirty newton meter
  • 00:14:50
    very difficult to design such kind of
  • 00:14:52
    motors with gears will bring the gear
  • 00:14:54
    later on
  • 00:14:55
    will require a high gear ratio sixteen
  • 00:14:57
    thirty newton
  • 00:14:58
    otherwise motor will not electric motor
  • 00:15:00
    will not be able to give you
  • 00:15:04
    ah but i had also added that starting
  • 00:15:07
    torque
  • 00:15:08
    20 percent slow that is 11.3 degree
  • 00:15:11
    slope
  • 00:15:12
    remember i had told you how to convert
  • 00:15:14
    the percentage
  • 00:15:15
    slope into degree
  • 00:15:18
    the torque required is 2700 newton meter
  • 00:15:24
    wow and torque is independent of
  • 00:15:27
    velocity so even at zero velocity
  • 00:15:29
    you require the same torque plus
  • 00:15:32
    even for point two meter per second
  • 00:15:34
    acceleration
  • 00:15:35
    to just get it moving um
  • 00:15:39
    you are not bothered about the speed at
  • 00:15:40
    that time get it moving
  • 00:15:42
    by 0.2 meter per second that's a
  • 00:15:45
    acceleration
  • 00:15:46
    you require another 700 newton meter so
  • 00:15:48
    you require almost 35
  • 00:15:50
    100 newton meter torque that's going to
  • 00:15:54
    be
  • 00:15:54
    not easy and that is something
  • 00:15:58
    you have to worry about when you design
  • 00:15:59
    a motor
  • 00:16:01
    so summary of the pickup truck it's a
  • 00:16:04
    low end pickup truck
  • 00:16:06
    we actually find that since it consumes
  • 00:16:09
    how much energy
  • 00:16:10
    it consumes about 250 wattage per
  • 00:16:12
    kilometer
  • 00:16:14
    so i if i have a 200 kilometer
  • 00:16:18
    i require a 50 kilowatt hour battery
  • 00:16:22
    i may require slightly excess because i
  • 00:16:24
    am not taking into account
  • 00:16:26
    the inefficiencies so 55 maybe
  • 00:16:32
    60 kilowatt hour
  • 00:16:38
    as 85 percent is used and
  • 00:16:41
    finally it goes to 80 percent because
  • 00:16:45
    the battery deteriorates
  • 00:16:46
    and still should give me 200 kilometer
  • 00:16:48
    my requirement goes to 75 kilowatt hour
  • 00:16:52
    i look at this 85 percent 80 percent
  • 00:16:54
    number
  • 00:16:55
    in greater detail later on
  • 00:16:59
    now remember that 75 kilowatt hour
  • 00:17:01
    itself will add 400 kg of weight
  • 00:17:06
    so my total gross weight has to include
  • 00:17:08
    this
  • 00:17:10
    if i have a smaller battery 50 kilowatt
  • 00:17:13
    hour it will be less
  • 00:17:14
    so we have to compromise i have to
  • 00:17:16
    figure out
  • 00:17:19
    computations carried out without taking
  • 00:17:21
    motor and controlling efficiencies
  • 00:17:24
    which could add another 15 percent
  • 00:17:26
    weight in size
  • 00:17:30
    so the motors and controllers will be
  • 00:17:32
    better designed
  • 00:17:34
    so you get good efficiencies but fifteen
  • 00:17:36
    percent
  • 00:17:37
    size torque requirement is about three
  • 00:17:41
    thousand
  • 00:17:42
    little more than that three thousand
  • 00:17:43
    five hundred at twenty percent
  • 00:17:45
    of slope single gear may be very
  • 00:17:48
    difficult
  • 00:17:50
    and yet one might try to do it with
  • 00:17:52
    single gear otherwise one has to do gear
  • 00:17:54
    change
  • 00:17:55
    in which case you have to have a clutch
  • 00:17:58
    which disengages the gear and then go to
  • 00:18:00
    another gear
  • 00:18:01
    remember that high slope when you are
  • 00:18:04
    trying to climb up
  • 00:18:06
    maybe just for that you may have one
  • 00:18:08
    gear
  • 00:18:12
    for acceleration you probably will
  • 00:18:14
    manage
  • 00:18:16
    this is what will be required so let me
  • 00:18:19
    come to the conclusion of vehicle
  • 00:18:21
    dynamics i have done that over last
  • 00:18:24
    last four four and a half five hours
  • 00:18:29
    one more thing that i actually did
  • 00:18:33
    after we computed this energy efficiency
  • 00:18:35
    i took this sedal
  • 00:18:37
    and say what if i vary the drag
  • 00:18:39
    coefficient
  • 00:18:41
    what will happen i have taken here mu to
  • 00:18:44
    be point zero zero six
  • 00:18:45
    and i vary the drag coefficient
  • 00:18:49
    as i vary the drag coefficient i see the
  • 00:18:52
    water per kilometer significantly varies
  • 00:18:56
    if my drag coefficient can go down to
  • 00:18:58
    0.25
  • 00:19:04
    then my energy requirement is only about
  • 00:19:08
    60 to 63 watt hour per kilometer this is
  • 00:19:11
    assuming
  • 00:19:12
    r equal to 0.5 regeneration on the other
  • 00:19:15
    hand if drag coefficient goes up to 0.5
  • 00:19:21
    then it goes significantly high
  • 00:19:24
    to almost eighty five ninety so one has
  • 00:19:26
    to be very careful
  • 00:19:28
    each of the parameters sensitivity this
  • 00:19:31
    is called
  • 00:19:31
    sensitivity analysis
  • 00:19:34
    i will be very careful that my cd does
  • 00:19:38
    not go up cd is as low as possible
  • 00:19:42
    similarly i look at fix the cd and start
  • 00:19:45
    varying the mu
  • 00:19:49
    the rolling resistance this time
  • 00:19:54
    now remember that you cannot do too much
  • 00:19:56
    about the area
  • 00:19:57
    it was c d into area so area you cant do
  • 00:20:00
    too much
  • 00:20:02
    c d is one thing that you can change and
  • 00:20:05
    the other thing is
  • 00:20:06
    this is not as bad but even here it goes
  • 00:20:09
    to 70 to 90.
  • 00:20:11
    well here it goes from 60 to
  • 00:20:14
    almost 8890 here it goes 72 to
  • 00:20:18
    90 and again ah
  • 00:20:21
    i had taken mu to be point zero six
  • 00:20:25
    if i increase it it can get very bad if
  • 00:20:28
    i
  • 00:20:29
    reduce it can go down now this
  • 00:20:32
    means value of a tire
  • 00:20:38
    remember somebody will say well it will
  • 00:20:40
    add
  • 00:20:41
    two thousand rupees extra for or all the
  • 00:20:44
    tire there are so many tires
  • 00:20:45
    in a sedan there are only four tires it
  • 00:20:48
    will add 5000 rupees
  • 00:20:50
    but if 5000 rupees will give me
  • 00:20:54
    10 watt per kilometer
  • 00:20:57
    reduction
  • 00:21:00
    you can just compute in no time
  • 00:21:04
    in a year you can recover that cost
  • 00:21:09
    this kind of optimization which is
  • 00:21:11
    extremely important
  • 00:21:15
    for electric vehicles your battery size
  • 00:21:17
    can go down your
  • 00:21:21
    that means capital cost cut down and of
  • 00:21:24
    course energy
  • 00:21:26
    will also go down
  • 00:21:31
    so this is something that ah i talked
  • 00:21:34
    about this is with
  • 00:21:35
    r equal to 0.5 and with 100 regeneration
  • 00:21:40
    it is much better
  • 00:21:42
    now so far i have not talked about
  • 00:21:43
    torque though i i
  • 00:21:45
    did compute torque the importance of
  • 00:21:48
    torque we have not
  • 00:21:49
    talked about torque is required one is
  • 00:21:50
    an acceleration again in the slope
  • 00:21:53
    and you will repeat it why we have
  • 00:21:55
    computed it so you will find it
  • 00:21:57
    that this is a major issue
  • 00:22:02
    as speed becomes high power requirement
  • 00:22:05
    goes high
  • 00:22:06
    torque remains more or less constant
  • 00:22:08
    does not depend on speed
  • 00:22:11
    so on the one hand i have to worry about
  • 00:22:13
    torque otherwise
  • 00:22:15
    i have to worry about power at high
  • 00:22:17
    speeds
  • 00:22:18
    and low speed power requirement is not
  • 00:22:19
    large if you saw
  • 00:22:21
    the number below 50 kilometer 60
  • 00:22:23
    kilometer very little
  • 00:22:25
    once you went to 1890 it went up so
  • 00:22:28
    power requirement
  • 00:22:29
    above 60 kilometer per hour you have to
  • 00:22:32
    worry about
  • 00:22:32
    if you go to 100 kilometer per hour or
  • 00:22:34
    130 or 150 kilometer hour
  • 00:22:37
    your power becomes very high
  • 00:22:40
    but don't do not forget power is a cube
  • 00:22:44
    of the velocity
  • 00:22:47
    so correspondingly your energy
  • 00:22:48
    requirement will also go up the battery
  • 00:22:50
    size will go up
  • 00:22:52
    ah so besides torque and power the other
  • 00:22:55
    critical thing
  • 00:22:57
    that has to be one has to worry about is
  • 00:22:59
    rpm
  • 00:23:01
    because rpm will give you what is the
  • 00:23:03
    speed at which you can go
  • 00:23:05
    you can design for power and torque
  • 00:23:08
    to go to 150 kilometer if your rpm does
  • 00:23:12
    not allow you to go to 150 kilometer per
  • 00:23:14
    hour what you use
  • 00:23:15
    of course both power torque and speed
  • 00:23:20
    you can multiply torque
  • 00:23:23
    divide speed by a certain factor
  • 00:23:27
    by the gear ratio of course if you
  • 00:23:31
    change if you have different gears that
  • 00:23:34
    is multi gear
  • 00:23:36
    which will require a clutch and all that
  • 00:23:38
    you can
  • 00:23:40
    use a different gear ratio
  • 00:23:44
    a smaller gear
  • 00:23:48
    ratio when at high speed
  • 00:23:51
    and we need high torque you can have a
  • 00:23:53
    higher gear ratio
  • 00:23:55
    but if you use a single gear you have to
  • 00:23:58
    balance between the two
  • 00:24:00
    we will learn all these things going
  • 00:24:03
    forward
  • 00:24:08
    energy required per kilometer and its
  • 00:24:10
    impact
  • 00:24:12
    i am repeatedly pointing out while we
  • 00:24:14
    are learn to calculate it
  • 00:24:16
    we have not taken into account
  • 00:24:18
    inefficiencies if we take into
  • 00:24:20
    inefficiencies
  • 00:24:21
    actual requirement we
  • 00:24:24
    is very close to what we computed we
  • 00:24:27
    just multiply by that inefficiency and
  • 00:24:29
    you will see that
  • 00:24:32
    we also require in the battery
  • 00:24:36
    when we talk about battery we will see
  • 00:24:38
    there are two parameters one is the
  • 00:24:39
    total energy required
  • 00:24:40
    another is a peak power requirement
  • 00:24:45
    a peak power means you are trying to
  • 00:24:47
    draw higher current from a battery
  • 00:24:50
    and as we learn as we talk about battery
  • 00:24:52
    you will see
  • 00:24:53
    higher current drawing large currents
  • 00:24:55
    also is a problematic
  • 00:24:57
    it impacts the life of the battery so we
  • 00:25:00
    will look
  • 00:25:01
    at what is called c rate
  • 00:25:04
    [Music]
  • 00:25:05
    the power requirement also in greater
  • 00:25:07
    detail
  • 00:25:09
    motor controllers have to be defined for
  • 00:25:11
    a certain output power
  • 00:25:13
    and torque and rather than input power
  • 00:25:15
    so
  • 00:25:16
    the input power could be whatever and we
  • 00:25:19
    have the inefficiency that means the
  • 00:25:20
    output power that i want
  • 00:25:22
    what we have all computed is output
  • 00:25:23
    power
  • 00:25:26
    one other issue that comes up if you
  • 00:25:28
    have larger inefficiency in motor
  • 00:25:30
    controller
  • 00:25:32
    your output power is much less than the
  • 00:25:34
    input power what happens to the rest of
  • 00:25:36
    the energy rest of the
  • 00:25:38
    power it actually dissipates as heat
  • 00:25:43
    so thermal will become very important
  • 00:25:45
    what will you do with the
  • 00:25:46
    you cannot allow it to keep on getting
  • 00:25:48
    heated up you have to remove that heat
  • 00:25:50
    so in motor and controller that also
  • 00:25:53
    will become very important
  • 00:25:55
    all the time so far we have not
  • 00:25:56
    considered the auxiliary power and
  • 00:25:58
    energy requirement in real vehicle
  • 00:26:00
    you will have to add this i think
  • 00:26:07
    the last thing that i want to actually
  • 00:26:09
    look at
  • 00:26:11
    what should be the drivetrain voltage
  • 00:26:14
    that i should use
  • 00:26:19
    well the one which is commonly used
  • 00:26:22
    actually is 48 volt
  • 00:26:24
    for small size vehicles very common
  • 00:26:27
    48 fold these have more or less become
  • 00:26:29
    standard throughout the world
  • 00:26:34
    for two wheelers three wheelers four
  • 00:26:37
    wheelers
  • 00:26:38
    in the marginal 48 volt is not good
  • 00:26:40
    enough
  • 00:26:43
    for in india
  • 00:26:46
    some four wheelers are defined at 72
  • 00:26:47
    volt 72 volt is not a standard in the
  • 00:26:50
    world
  • 00:26:50
    it is more used in india 48 volt is very
  • 00:26:53
    common
  • 00:26:55
    as you go higher vehicle
  • 00:26:58
    cars you tend to go to higher voltage
  • 00:27:02
    why because for the same power if
  • 00:27:05
    voltage goes high
  • 00:27:06
    current goes down if voltage is small 48
  • 00:27:10
    volt
  • 00:27:11
    your current will be 200 300 amperes
  • 00:27:15
    anytime you have to use 200 to 300
  • 00:27:17
    ampere
  • 00:27:18
    first all your battery should be capable
  • 00:27:20
    of giving that not easy
  • 00:27:22
    you will see that number two lot of heat
  • 00:27:25
    dissipation i square r loss will always
  • 00:27:27
    there even a conductor he has a
  • 00:27:29
    resistance i square law
  • 00:27:31
    r loss will be there large current i
  • 00:27:34
    square so if you limit yourself to 100
  • 00:27:37
    ampere
  • 00:27:38
    you will get loss is 100 square into r
  • 00:27:43
    if you go to 200 amperes your actually
  • 00:27:47
    losses become 4 times and if you go to
  • 00:27:49
    300 ampere
  • 00:27:50
    losses become 9 times
  • 00:27:54
    so you if you go for higher voltage your
  • 00:27:57
    current can be smaller
  • 00:27:58
    and that's the reason for motors up to
  • 00:28:00
    75 kilowatt
  • 00:28:02
    this is used for motors up to 12 to 15
  • 00:28:05
    kilowatt 15 kilowatt
  • 00:28:07
    you know 15 kilowatt itself at 48 volt
  • 00:28:09
    is 300 amperes
  • 00:28:13
    at 350 volt if i go to 75
  • 00:28:18
    i am still talking about slightly higher
  • 00:28:21
    than 200 mps
  • 00:28:25
    and for even higher power
  • 00:28:28
    you go for 750 volt 80 kilowatt to 300
  • 00:28:32
    kilowatt
  • 00:28:32
    now of course that 300 kilowatts you
  • 00:28:34
    still have a very very high
  • 00:28:37
    current requirement of 400 mps
  • 00:28:41
    but i haven't seen vehicles going above
  • 00:28:43
    750 volt
  • 00:28:46
    so these three are emerging to be
  • 00:28:47
    standard 48 volt
  • 00:28:49
    350 volt 750 volt
  • 00:28:52
    and everything will have to design motor
  • 00:28:54
    and controllers to design battery has to
  • 00:28:55
    be different design
  • 00:28:56
    your converters has to be designed
  • 00:28:58
    accordingly
  • 00:29:02
    there is one more concept which will not
  • 00:29:04
    deal with in this course
  • 00:29:05
    can i use distributed motors can i use
  • 00:29:07
    four motors
  • 00:29:08
    on four different tires
  • 00:29:11
    my cost goes up but my can my reduce
  • 00:29:15
    my reduce my my
  • 00:29:18
    increase my energy efficiency use less
  • 00:29:20
    energy per kilometer
  • 00:29:22
    can i have more maneuverability all this
  • 00:29:25
    is possible
  • 00:29:26
    so you will see more and more
  • 00:29:28
    distributed motors instead of one motor
  • 00:29:30
    driving the whole vehicle maybe two more
  • 00:29:32
    or maybe four motors
  • 00:29:34
    and you will see that finally
  • 00:29:37
    what did we do in this chapter and why
  • 00:29:41
    an electric vehicle would have to have a
  • 00:29:44
    motor and controller
  • 00:29:46
    we have for that computed what is a
  • 00:29:48
    torque requirement
  • 00:29:52
    we have computed what is the
  • 00:29:55
    energy required power requirement for
  • 00:29:57
    the motor
  • 00:30:00
    battery will have to have sufficient
  • 00:30:01
    energy so we have actually
  • 00:30:04
    talked about what is the energy required
  • 00:30:05
    to move a vehicle
  • 00:30:07
    go to a certain drive cycle
  • 00:30:11
    and at every instant it should be able
  • 00:30:13
    to give me a give
  • 00:30:14
    sufficient power to motor and controller
  • 00:30:16
    that's what
  • 00:30:18
    well we have tried to figure out
  • 00:30:21
    we have learned to compute power energy
  • 00:30:24
    and torque
  • 00:30:26
    for different way vehicles
  • 00:30:29
    at different speeds of course at
  • 00:30:31
    different speeds and this is something
  • 00:30:33
    that we will be
  • 00:30:34
    doing more and more we also learned the
  • 00:30:38
    impact of various vehicle parameters
  • 00:30:40
    like rolling resistance
  • 00:30:41
    aerodynamic resistance vehicle frontal
  • 00:30:44
    area
  • 00:30:44
    weight slope pickup acceleration
  • 00:30:48
    regenerative requirement
  • 00:30:51
    on power energy and torque and all at
  • 00:30:53
    different rpm
  • 00:30:55
    and we have touched upon we haven't
  • 00:30:57
    really covered this
  • 00:30:59
    the impact of gear ratio which i will
  • 00:31:01
    actually do in the next
  • 00:31:03
    next chapter
  • 00:31:07
    what we will do having done that i am
  • 00:31:09
    going to go to the overview now
  • 00:31:12
    chapter 3 will look at
  • 00:31:15
    the subsystems of electric vehicle
  • 00:31:18
    where we will also look at what motors
  • 00:31:20
    are controlled what battery
  • 00:31:21
    what is the gear ratio that you require
  • 00:31:24
    what are the parameters for a vehicle
  • 00:31:26
    and what are the sub systems
  • 00:31:30
    after that in chapter 4
  • 00:31:33
    we will do fundamentals of batteries
  • 00:31:38
    then chapter 5 and 6 will run
  • 00:31:41
    concurrently
  • 00:31:42
    one on motor and controller another is
  • 00:31:44
    details of battery
  • 00:31:46
    design getting into the details of
  • 00:31:47
    battery design
  • 00:31:50
    and then in chapter 7 we will talk about
  • 00:31:54
    charges and charging infrastructure and
  • 00:31:57
    finally we will end
  • 00:31:59
    by talking about the
  • 00:32:02
    overall what kind of in management that
  • 00:32:06
    you do
  • 00:32:07
    when you try to run electric vehicles
  • 00:32:11
    ok i have completed this second chapter
  • 00:32:14
    which is a very important chapter
  • 00:32:16
    which actually helps you understand
  • 00:32:20
    what is the force
  • 00:32:24
    torque energy power
  • 00:32:27
    at different rpm for all kinds of
  • 00:32:30
    vehicles
  • 00:32:34
    this as i pointed out right in the
  • 00:32:36
    beginning
  • 00:32:37
    would be done for even a
  • 00:32:40
    internal combustion engine vehicle
  • 00:32:44
    petrol vehicle diesel vehicle more or
  • 00:32:46
    less the analysis is same
  • 00:32:48
    we may use few terms like regeneration
  • 00:32:51
    is unlikely to
  • 00:32:52
    be there in a petrol vehicle though
  • 00:32:54
    today's petrol vehicle have a electrical
  • 00:32:56
    battery
  • 00:32:57
    and does a regeneration
  • 00:33:02
    because the transition is going on
  • 00:33:07
    so that much is common so automotive
  • 00:33:10
    engineer would probably already know
  • 00:33:12
    that
  • 00:33:12
    but here i trained we also got it for
  • 00:33:15
    electrical electronics computer science
  • 00:33:18
    civil
  • 00:33:19
    aeronautical engineer to figure this out
  • 00:33:23
    one thing that i have not done
  • 00:33:26
    i have done all kinds of vehicles two
  • 00:33:28
    wheeler three wheeler four wheeler
  • 00:33:29
    trucks
  • 00:33:30
    now pretty much any other vehicle can be
  • 00:33:33
    figured out what i did not do
  • 00:33:40
    is a boat or a aircraft
  • 00:33:48
    both are vehicles
  • 00:33:54
    the mechanism is not exactly the same
  • 00:33:56
    but a very similar approach
  • 00:33:59
    let me see at least if i can do
  • 00:34:02
    something towards the end
  • 00:34:03
    on a aircraft the because a lot of uai
  • 00:34:07
    lot of youngsters are not designing ui
  • 00:34:10
    what is the motor required what is the
  • 00:34:12
    battery required at least you will
  • 00:34:14
    figure it out
  • 00:34:16
    okay and
  • 00:34:20
    want to point out that a good
  • 00:34:21
    understanding of vehicle dynamics
  • 00:34:22
    prepares ground
  • 00:34:23
    for av sub systems design
  • 00:34:27
    ev drive trade requirements come from
  • 00:34:29
    this power talk
  • 00:34:30
    speed and energy consideration at
  • 00:34:33
    different
  • 00:34:34
    rpm different speeds because very
  • 00:34:37
    important
  • 00:34:40
    i have we have given a number of
  • 00:34:41
    assignments throughout the
  • 00:34:43
    chapter please do that
  • 00:34:46
    a lot of learning will come from those
  • 00:34:49
    assignments thank you very much
Tags
  • véhicules électriques
  • cycle de conduite
  • efficacité énergétique
  • aérodynamique
  • traînée
  • batterie
  • moteurs PMSM
  • moteur à induction
  • camions électriques
  • gradabilité