Assignment 2.1

System engineering integrates the knowledge of different disciplines. Therefore we prepared materials to involve teachers from different disciplines.

Step 1: Please watch the introduction video.

Step 2: Please read the slides below and watch the first lecture This material explains the concept of
an e-motor on a high level and outlines why teachers from physics, chemistry, mathematics, biology, ethics, informatics, languages are all involved in this system engineering topic.

Introduction E-Motor

Step 3: Now we are asking you to post your findings and questions here. The facilitators will try to answer your questions and looking forward to a fruitful discussion with you!

74 thoughts on “Assignment 2.1”

  1. First of all, I have to say that the general idea of mooc is good. I watched the Assignment 2.1 which deals with the topic „basics about the e-motor“. It’s very important to talk about current issues like climate change and how innovations like the e-motor could change the world. The lesson was quite interesting and understandable, although there was to little information in some areas. However I don’t agree that this is the ideal solution for reducing air pollution. I think that car driving must generally be made unattractive, because the production of electric cars is also very harmful to the environment. Despite this „negative” facts, it’s good to make such videos or plattforms to inform the teachers and the students and make them familiar with such topics.

  2. First of all the introduction at the Assignment 2.1 is a meaningful overview about the hard facts dealing with global warming and CO2 emission. Global warming is a current issue in today’s society. It will become one of the major aspects in the future. Therefore this information is essential for the motive to produce and develop e-motors and extend the production of cars with e-motors.
    In the beginning it is demanding to follow the explanation of the lector, but at an advanced time you get familiar with the topic and in the end you have a basic knowledge about the functionality of the e-motor.
    Furthermore it is interesting which subjects are essential to create and improve an e-motor.
    Unfortunately I have noticed that your presentational style needs some improvements. Try to be more creative sometimes, because the internet is over-flooded with information and in my opinion it is the challenge to stand out of those.
    All in all it is a very important topic and your Elic-Mooc is a good start.
    Hopefully it becomes more important in the future.

  3. Hello people, my name is David Pepper and I am 18 years old. I am a student at the BRG Kepler in Graz and I found this website in a physic school lesson. In my opinion it is all in all a great idea to get more youth in to engineering programs, but I do not think that this course helps to get to this achievement. At first, I have to say, that the English which is used in videos should be appropriate for teachers and I think it is not. I found many spelling and accuracy mistakes.
    In addition to that I think, that there are much better ways to show teachers how to teach students and how to cause more interest among teenagers on a certain topic. For example the video about the basics about E-Motors. I think that there is enough literature about this topic nowadays, so if you want to get the attention of the youth then you have to be more creative. Like you can make excursions to some fabricates, which make those cars.

  4. I read the articles about the E-Motor. The Private Assignment 2.1 is very well-developed. The explanations are very intelligible and suitable for students and teenagers. The students understand that there are many complex problems in our society, especially climate change and global warming. The E-Motor provides us with a serious solution for these problems. Not talking about environmental issues is very dangerous, because the students are willing to underestimate climate change. Your presentation tackles this problem.
    You make it clear that there are several elements which are essential for building a proper E-Motor. Also it is very intelligible why the knowledge of different disciplines, like Physics, Chemistry, Mathematics and Biology, is needed.
    I would like to admit that i miss the reasons why the technology is not enough developed for topping the bill. Moreover I would like to learn more about the promotion of lithium which is needed for the batteries of the E-Motor.

  5. I think one of the most important teachings we can give to our students is that there are no simple answers to complex problems. In the first classes one of the main themes of natural sciences concerns the use of fossil fuels and global warming. Talking about environmental issues one of the topics on which I try to make my pupils reflect is that of Ecological and Carbon Footprint, in particular with regards to “green” products and technologies. Often I choose a product that my pupils know well (things that most attract their curiosity are smartphones… and coke!) and I try to make them reflect on the ecological impact and energy demand starting from the production or extraction of raw materials to the manufacturing, transport, use and end of life phases. It could be interesting to examine the CF impact for electrical products.
    Here some tools to calculate CF… Footprint Calculator

    1. Very nice!
      Indeed the lifecycle assessment is becoming important, it will be required in the future – se my posts here and in 2.2!

  6. The lesson was quite interesting, and highlighted the multidisciplinary nature of e-motor technology. I do not agree to consider this type of technology as the ideal solution for reducing pollution and CO2 emissions, because this is not the case; at the moment these technologies, which are now emerging on the market, are only one of the many efforts made to solve problems but at the same time they have created others, no less serious. This topic with the pupils must surely be tackled critically and without neglecting the environmental aspects that must certainly always be underlined and deepened.

    1. Technics is a physics with limitations. As an engineer I work with the best available solutions. But I always try to find a better one.

      At this point I believe that the electric motor is the best available solution. But it is certainly not ideal.

  7. The subject is very interesting and interdisciplinary, it concerns different aspects of the real life, raises people’s awareness and influences their choices. Many colleagues have already posted very smart comments about the pollution, the alternative sources of energy, etc. I would like to focus my post on the ability of the students to read and interpret data presented at the beginning of the video (“Did you know?”).
    This is one of the four areas tested by INVALSI (National Institute for the Evaluation of the Educational System of Education and Training): data and predictions. This Institute shares various aspects with TIMSS (Trends in Mathematics and Science Study) and with OECD-PISA (Programme for International Student Assessment) and structures its tests in four areas: numbers, spaces and figures, data and predictions, relations and functions. In my experience as Maths teacher I notice the students run into difficulty if they have to collect, sum up, present and interpret data. This is a big problem because it could complicate potentially the deep understanding of the meaning of the subject matter (in this case the slides “Did you know?”). The (ethical) precondition for studying the e-motor is the comprehension of the reality of situation. Collecting data, reading graphs, interpreting numbers are fundamental passages.
    It’s a little strange, but sometimes it’s easier to teach/learn to use the trigonometric functions and the phase shifting on the basis of their definitions.

    1. I agree with your statement that sometimes definitions are an easier way. But I also think some practical example can improve the understanding. The sad fact is that even at the University I sometimes encounter students who have learned the lecture word-by-word, but completely fail to demonstrate any understanding.

      In my work I often have to learn new theoretical issues and I have to understand them. It always helps to have an example. For example I try to understand the fractional calculus (, mathematical formulas are clear, but it is the meaning in real world that makes me problems. Hoe can there be a “half derivative”… For students with less knowledge in mathematics, trigonometry presents the same challenge.

  8. I think that to study electric motor students need the prerequisites already listed, to achieve the skills are useful experiments and activities that involve and are interesting for them. One of the devices I used is a homopolar motor made with a self-tapping screw, a battery cell, a wire, and a disk magnet.
    Very useful the links for the basic knowledge proposed by Milo2.

  9. Stringent emissions regulations have driven most manufacturers to focus on electric mobility. The major obstacle still difficult to overcome today for this technology concerns the autonomy of the batteries and the charging speed of the same, in addition to the rapid spread of the charging stations.
    Some car manufacturers have adopted lithium batteries, of which they declare an autonomy that varies from 200 to 400 Km, but obviously this can vary according to the driving style adopted by the driver.
    In my opinion, electric mobility is a reality that is still not convenient and has little incentive.

    1. The research is ongoing and the technology is getting better. The energy density of lithium batteries is currently 250 Wh/kg to 450 W/kg, lithium could have up to 1000 Wh/kg, based on what researchers in the field claim – so the distance could be significantly increased.
      Regarding the charging – you can charge a car slowly overnight or use the fast chargers on the gasoline stations. The 340 kW charging has been recently reported. The charging can even be wireless, see

  10. In my opinion, a problem with electric cars is the ability to efficiently store energy.
    Electric current cars are equipped with lithium batteries, however this metal shows some safety problems and also high cost.
    Anyway a new accululation technology has been found wich is alternative to the electrochemical batteries :it is called supercapacitor.
    Supercapacitors can be charged or discarghed almost immediately and have positively higher life compared to electrochemical devices.
    Some Universities ,such a Bristol University and Surrey University, are testing a new polymeric material with much greater dielectric properties. A new polymeric material could be developed to increase the energy density of supercapacitors with dielecric properties of 1000 to 10000 times greater than the standard electrolytes.
    Supercapacitors could store a much higher energy density than currently available lithium batteries.
    With these materials you could recharge a car in 10 minutes in the near future!!

    1. Just an explanation. Currently used ultracapacitors have a higher power density than currently used batteries, but a much lower energy density. See the table in Wikipedia ( Energy capacity or specific energy is the amount of energy that can be stored per mass unit. This then determines the range of a car. Power density is based on how much power the battery can provide or store per mass unit. For example how fast it can be charged or discharged. In batteries this is also sometimes represented with Cs – 3C, 5C, … If the battery has 1 Ah and 3C it can be discharged with 3A.
      But this is a very good example of the improvements being made in electric vehicles. Very nice input!

    2. In the current Automotive projects the supercapacitors are used but they have still limits. While it might charge and release energy faster than standard batteries, they currently don’t hold nearly as much energy. This is one aspect that the scientists hope to change with further study.
      See .
      The supercapacitors nowadays are able to hold for about 4 seconds and are used for starting the car when we lost the battery power. Once the car runs the battery will load.

      Another approach which large companies like BOSCH implemented (will go to road this year) is a so called range extender principle. There is the electric motor which provides torque and there is a small combustion engine (not related to the powertrain) just used for reloading the battery during drive. The combustion engine is only used when the battery load is lower than a defined limit. This way an electrical car can drive nearly unlimited but we still need approx. half a liter fuel per 100 km.

  11. A few months ago I had the opportunity to spend a full day at, a place where students and teachers could understand and test the principle of the lean manufactoring updated to Industry 4.0. It was clear the importance of automation applied to industrial processes and the links between electronics and information technology. Our students came from two curricula, mechanical and electronical: both were involved in the same topic, so I think they could appreciate this inter-disciplinarity, moreover applied to an ethical problem, i.e. the organisation of a factory in order to avoid waste of materials, money and overall time.
    I think this is a good example of a new way of teaching to secondary school students.

    I’ve read the comments concerning pollution and I think that the E-Motor can’t solve all the problems we are facing, nor fuell-cells. Hydrogen is a carrier, like electricity, and we have to spend energy to get it, in particular for fuel-cells driven vehicles, that requires pure H2 to work at low temperature because of the platinum based catalysts required for the electrochemical reaction. Moreover, fuel-cells have a low weight to power ratio and are expensive, due to catalysts and supports, based on precious metals and rare earths elements. Population is growing like metropolis. Now, the catalytic converter applied in the seventies to survive in Los Angeles is no more sufficient, and we should move pollution away from cities. We could with electric cars, but electricity must be produced: in fact, we are only moving pollution and the global balance doesn’t change.

    1. Indeed the institutes that you mention are good. They should be more. Also “House of experiments” (an example: is a good idea.
      Regarding the electric motor – it has solved a lot of problems and it will certainly be a part of solution for the mobility. But no device or tecnology can solve all the problems. If you read my comments in this section and section 2.2, you will see, that the polution is in fact much reduced if electric vehicles are used instead of ICE ones. Not only regarding the use of the car, but also the consumption. This is something researchers have demonstatrated in many scientific papers. Of course there are some people, who sometimes claim that this is not true. But there are also people opposing vaccination, some even claim the earth is flat (and the most funny thing is that they claim to have supporters “arround the globe” 🙂 ).
      I do hate it to sound like a religious zelot, as I already wrote enthusiasm is not scientific. But electrical vehicles are comming, if they will not be produced and used in EU, they surely will be in China. If we reject the technology, Chinese will not and in a long term they will collect the jobs from European car industry. Just look what Japanese did to USA.

  12. If I miss the answer to somebody – please appologize. I will eventually find it.
    This forum is becoming huge… Nice. 🙂

  13. I agree with my coworker Giovanni Garlatti. It is very important to understand the basic of electrical engineering because all of devices are controlled by these laws. Moreover modern industry works towards more automation processes (industry 4.0). For this reason we should motivate our students to study physics, chemistry ecc… Connected with these topics I think it is important discuss about pollution and environment problems, and also we should talk about clean energy. E-motor with zero emission is not possible, because electric power is produced by plants which produced C02 emission. Because of this I think the aim of humanity is to find and improve our energy production plants. Personally I often debate with my students about sustainable energy and wastefulness. I found these ethic topics interesting because they affect everyone. I think E-motors are the right technology suitable for all, in particular, the development of E-mobility service in our cities is the future.

    1. I completelly agree.
      The issue regarding the efficiency is also important. A lot has already been done – just compare the use of energy at your home now and when you were a child. Still falling.
      Also a lot can be done with little effort – they put the reflectors / shades on the top of lights in my town. Now they use less energy and I can see the stars.

  14. it is right for me to try to make electric motors evolve so as to make the planet in which we live less polluted and emission-free, so as to delete global warming that no longer allows us to live the seasons as they should be.
    triggering catastrophic phenomena always more frequently.
    but is it really so? … I’m not sure, understanding that today’s electric cars eventually have co2 emissions at the end of their life cycle not too much lower than diesel engines.
    Considering also the construction materials used above all in the batteries that are among the other dimensions tens of times larger than the “normal” cars. In any case the work to turn the whole system to the electric is still very long.
    And how much will it cost in terms of environmental impact? ..
    it will be remarkable and I honestly do not know how worthwhile it is

    1. I posted yesterday on 2.2 regarding that issue – is has been shown that even with craddle-to-grave (this is not a joke, we really call it that way) CO2 consumption is better for electric cars than for the ICEs.
      Batteries are an issue, they do age. But they can have a long second life as energy storage, which is anyway required for integration of more renewables. And they can be recycled. Because lithium is worth it. The research in this field is quite strong.

  15. As for the future of electric cars, I think that how, how much, when it will be decided as always by those who manage the world economy. The same goes for the production of electricity using “green” methods.
    As for teaching, to understand the functioning of an electric motor, I think it is necessary for children to be able to answer the following questions:
    – What is an electric current?
    – What is a Voltage? (electric field)
    – What happens to a current wire immersed in a magnetic field? (Faraday experience)
    – Why does a current-driven coil generate a magnetic field? (Lenz)
    – Why does alternating current have a sinusoidal pattern?
    These are all questions that are dealt with in the last year of the scientific high school.

    Sorry for the incorrect English, but I entrust the translation to google translator

    Best wishes


    1. You are right regarding the electricity. Probably Kirchoff laws should also be included. Maybe you should only consider that an electric motor is an electromechanical device, so you should add:
      – Newton laws – for translational and rotary motion (force and torque)
      – Power
      – Energy
      Your English is excelent. And even if it would not be, usually we would figure it out. Don’t be affraid, you will be understood, just ask more questions. Smart people say that we learn from our mistakes. 🙂

  16. Hi,
    it’s a interesting session. I have doubts about the autonomy of e-car and the CO2 emission.
    In relation to the Maths topic, it’s good way to show students how useful maths is, but maybe for some pupils could be too dfficult to understand. Are there other possible connections to Maths area?

    1. Of course the three phase motor is a hard thing to understand. But maybe you can also start with a car on the slope. You have the angle there. And you could let the students calculate energy of the car driving uphil with a speed of x kmh. That is for basic trigonometry.
      I also teach programming in C in the first year of university. The first task is to calculate power from hp to kW. They really start with zero knowledge and finish with making quite complex programes. You could also try with rpm to rad/s.

    1. There is the concept of an electric retarder which is used.
      So why do we still use brakes in the car then ? There is a safety law for cars producers that brakes must be constructed that they never fail. Therefore we need two redundant brake cycles in a car, and as a fall back we have to have a traditional brake with clutches on wheels like in the past. Since we have only one e-motor in the car, what would be the fall back concept?
      For some time then then an e-car was considered with 4 in wheel e-motors, one per wheel. The problem then was that we got worse safety conditions, imagine that one inwheel motor on the friomt axle brakes, the other not, while braking.
      As long as we do not find a safe brake with fall back, the brake design concepts will not change.

      1. Induction motor can be and is use for braking. All types of electric motors can be. If it is operated in generator mode, it is producing negative torque (different direction than speed). There are even designs for electric brakes for trucks (I saw one 25 years ago, by Bosch).
        The electric braking is really used in the same way as the braking with the motor. If you drive downhill, you put to a lower gear… Only that motor produces electric energy, which can be used for charging the batteries – like the fuel would be running to the reservoir.
        But rmess is absolutelly right, it is the safety concerns. Cars are designed as safely as they can be. And I belive in future this issue will be solved with redundancy. Some vehicles in industry, like forklifters, can even now be completely without mechanical brakes. The problem then is what to do if the battery is full – think about that!
        BTW, also robots in many cases have additional brakes.

  17. I teach Hygiene and so there are some good ideas that can be developed from this topic.
    Fine particulate matter poses a health risk (especially as a risk factor for chronic respiratory diseases); therefore, using less fossil fuels in cities can bring health benefits (also for no NOx emissions).

    But is it worthwhile converting the entire vehicle fleet if the real efficiency of the electric car is only about 28% (compared to an average “thermal efficiency” of 20% of the Internal Combustion Engine)?
    Changing the whole fleet has an environmental cost (waste products and new cars to be built using raw materials).
    Moreover: how much is polluting the production of batteries?
    Finally, if the batteries are lithium batteries, you have to consider that lithium is toxic (in addition to the problems related to its extraction).

    1. The 28% is well-to-wheel (WTW), if you compare that to ICE vehicle, ICE has less. Please, keep in mind that the data is always biased based on who gives it to you. Diesel-people will give you WTW for EV if the oldest coal powerplant is used and data for diesel for tank-to-wheel. EV people will give you the data for renewable energy source. It really depends on the energy mix.
      When it comes to lifecycle energy, EV is also not as good. But – and this is important – the goal is to use as much renewable sources as possible. So the future is brighter fore EVs.
      It is true about lithium. But this is a problem that has to be solved by recycling and clean production. Can be done. There is not a lot of lithium, so we will want to recycle it.
      Finally, oil is also a pollutant. Remember Mexican Gulf, Nigeria, … I can assure you that if the cars would be electrical and somebody would propose gasoline to be used, the person would be hanged.
      Really – just look at the simple facts – how many electric motors do you have at home. This can be assignment for students! And how many ICEs? Now why would that be? 😉

  18. I think that the assessment of the environmental impact of electric vehicles with respect to those with internal combustion must be assessed very carefully. My colleague lucamarisa has done a very precise and thorough analysis. With the transition to electric vehicles, pollution is considerably reduced in urban areas. However, if the production of electricity, as in Italy, is made mainly from non-renewable sources, the reduction of global pollution is certainly much lower.

    1. The production of electricity in Italy is not really a good example. Italy is a big importer of electrical energy, so pollution in many cases is in countries like Ukraine… 🙂
      But, people are working on that issues. The assessment, especially lifecycle assessment (LCA), is very important. I found some data for Italy, regarding the LCA for a vehicle. I don’t know if you can access it (, but it is really nice. BEV performs much better in most of categories. And the paper is from 2013!
      And a nice comparison of Ford Focus and Mitsubishi i-MiEV:
      And you can simple google for more “electric vehicle LCA”. Let me know what you discovered!

  19. Just for the info, due to the reasons beyond my control, my username had to be changed, so I will post under MiRo2, but I was formerly known as miranro. Just to avoid confusion. It is the same person.

  20. I have a small question about the first part of your slided, where you talk about climate change:
    When you talk about fine dust, do you mean CO2? Or persists find dust of different components and CO2 is only one of them?

    1. CO2 and fine dust are not the same thing. Emissions contain CO2, Nox, fine dust, …
      Fine dust is made of very small solid particles, few micrometers in diameter. It comes from burning diesel, solid fuels (also wood) etc. Just as an info – normal gasoline also produces some fine dust, but they don’t measure it, yet.

        1. That is it.
          BTW, these particles in gasoline are supposed to be sub-micron.

  21. Thank you for this useful comment that defines significant themes to treat during Mathematics lessons!

      1. You are welcome. BTW, I had to change my username… Don’t have a clue why.

  22. I’ve honestly tried but I ‘ve found the content of the video extremely difficult for me (remember I teach English). As previously mentioned, I teach ESP and motors are part of the topics that we discuss in class; I was hoping to find something to share with my students but first I need to grasp something in order to teach it. I need to develop some form of understanding (literacy)…
    The introductory 5’ are quite interesting though, and I will try to use the info given and the links provided in the posts as a topic for discussion in class.

    1. In a car we have between 80 and 120 computers (we call them ECUs – Electronic Control Units). The ESP (Electronic Stability Program) is usually combined with the ABS brake system and e.g. inner wheels are slowed down in a controlled way to support driving curves.
      The e-motor is managed by a different ECU in the car (vehicle controller) and creates torque and therefore torque on the wheels.
      So while the motor creates the basic torque, the ESP slows down wheels in a controlled way. So ESP is more related with the ABS brake system and not the motor. Hope this info helps.

    2. hello, for the basic knowledge, there is a nice presentation on Howstuffworks:
      You can also see some quite basic explanations on youtube:
      The idea of preparing the materials was to make them for physics, math and similar.
      And, to be honest, maybe also I am involved with this motors too much, it gets hard to explain things simple after some time.

  23. 1220/5000
    It is with great pleasure that I begin to learn something about the e-motor. I am obviously not able to comment on the technical aspects of engineering systems. The idea of ​​team work fascinates me a lot. I am sure that in partiular in the Italian educational system we must increase the team work skills. However, there are some objections. In the video it is said that nobody knows everything about the process and that the disciplines, chemistry, physics, electronics and computer science, etc., contribute to the result each for a different aspect. I wonder if the increase in specialization does not deprive individuals of the faculty to operate then ethical choices. in the sense that there could be the risk of losing sight of the final and global goal.
    As far as Global Climate Change is concerned, I do not think the solution can only be technical. On the contrary, by doing so we lose a precious opportunity for true and profound change. The solution can and must be first of all Political, ideological and revolution of the man / nature and man / technology approach. The only technical solution will continue to produce social imbalances in the world and make the price pay only to the most economically disadvantaged areas of the planet.

    1. It is always also a combination of both, a new invention and a new political decision. There is, for instance, a lot of additional research to solve the current problems. Here are some examples:

      Bacteria that eat CO2 (terra forming ideas to get rid of CO2)

      Hydrogen driven cars by fuel cell
      The problem is that the current production is too expensive, but what happens if politics decide to invest into that. BMW has a fleet of such cars.

      The Blueprint Automotive Projects of the European union support the movement to electric but also self driving vehicles in the future.

      So yes, politics will decide, but still electric powertrain is currently the main direction of most suppliers and OEMs (BOSCH developing range extender solutions, MAGNA developing 48 V hybrid and 400 V e-motor, ZF developing e-motors also for trucks with 600 – 800 V batteries. etc.) In China they force you to the electric car, otherwise the car is not affordable (for combustion engine you must win a lotto and if you won you pay a high price).

    2. In daily life, most people don’t act according to their ethical beliefs. They choose to do what satisfies their basic needs in the easiest way. If one easy way meets their belief system, they will do it (even if there is a slightly easier way). If organic food was cheaper than other food, everyone would buy it.
      And that is the part, technology has to play: Making the good choices as easy as possible to follow.

      1. That is sad but true. But in the production of cars volumes reduce prices. The number of electric cars produced will grow and the prices will fall.
        And I dare to claim that when the price is low enough, the electric car wil be more convenient choice. It will be even more user-friendly.

        1. Also regarding the economicaly dissadvantaged. They will benefit,too. They will spend less for energy.
          There is also an interesting calculation I came accross some time ago. Sorry, but I can’t find a link… The price of transportation should fall to 10% when autonomous cars will be dominant. The cost of car, its ownership, … will go away. I only worry about all the workplaces that will not be needed in car industry, transport etc.

  24. I would like to add some personal observations on what is reported in Module 4 – E-Motor Introduction and in particular on the pollution produced by electric cars. In particular I do not agree with the statement that “An e-motor concept helps to achieve zero fine dust emission from cars” (as reported in the slide n ° 3): in fact it is well known that a non negligible part of PM10 and PM2.5 derive from tire and car brakes wear.
    At the current state of the art, electric cars continue to use conventional brakes and tires, so in my opinion the zero emission of fine particles is not an achievable goal in the short term.
    The reduction of the direct emission of some pollutants linked to the diffusion of electric cars remains unquestionable; in the absence of combustion, in fact, there is no emission of nitrogen oxides (NOx), carbon monoxide (CO), unburnt hydrocarbons and volatile organic compounds (essentially HC).
    On the other hand, if we evaluate global greenhouse gas emissions, the advantages that can be obtained by using electric cars depend on the techniques used to produce the electricity needed to recharge the batteries.
    In countries where electricity is generated from renewable energy sources, or from nuclear energy, the benefits in terms of reducing greenhouse gas emissions can be substantial but, on the contrary, emissions can even increase in countries where electricity is mainly generated using non-renewable energy sources such as coal or oil.

    The following map shows the carbon emissions caused by an electric car, in gCO2e/km (gram of CO2 equivalent) by country. This should be compared to the carbon footprint of a diesel car (170 gCO2e/km) or gasoline car (180 gCO2e/km), which are currently the most common types of vehicles.

    Another point of discussion is the environmental impact of the manufacture of electric cars: it is well known that electric car manufacturers tend to use light materials such as aluminium alloys or composite materials to compensate for the weight of batteries. Therefore it is easy to understand that the construction of electric cars requires more energy than the construction of traditional cars.
    I would like to make an observation about the problems related to the materials used in the construction of electric cars: the batteries that are currently used are based on lithium which is classified as a critical metal due to limited availability.
    Finally, it must be said that almost all electric car manufacturers use neodymium permanent magnets in the construction of electric engines; currently the neodymium market is 95% controlled by a single country (China), making it likely for the other countries to have serious problems with the supply of the necessary raw materials.

    1. There is no solution for all problems, but with the electrification the problems are reduced. There are less emissions, less pollution, etc. Engineers are problem solvers, not miracle makers. 🙂
      Regarding the overall impact, the new thing is CO2 labeling ( Whole lifecycle of all cars (and also other products) is be evaluated.
      the tyres for electric cars in fact have some different requirements than the ones for gasoline cars. For example, the acceleration is higher, due to the high torque at zero speed, which is available for electric motors.And braking can be done with the machine – then the motor is in generator mode and it also produces energy.
      When it comes to rare earths, you are absolutely right. Chinese own that market. And also some other ones. EU is sleeping, we have no major EV battery producer. See Something needs to be done.
      But, the reason for the Chinese supremacy in the rare earths market is actually due to the fact, that it is a very dirty process, which would cost a lot in EU or USA. But, when they tried to capitalize on that few years ago, some mines immediately opened in Australia. And some motor technologies have no permanent magnets, like induction motor, reluctance motor,… With only slightly lower efficiency.

  25. I first got in contact with brushless motors in modelling. There I have had an outrunner without encoders. How does the speed control manage to determine rotor position?

    1. The BLDC motor is usually controlled in such a way that it always has one phase unconnected. On this phase the voltage is measured, it is the back-emf. The transfer of this voltage through zero (the voltage is kind-of sinusoidal) is detected and this is how you get the position. This is called sensorless operation.
      For details you can read:
      There are also more complex and precise methods, but they almost always use the back-emf.

      1. Thanks very much! Am I´m right that this operation is not as smooth than the full 3phase operation with sensors?
        Other question: In Fig. 3 (pdf linked above) there is a strange waveform in the phase-current. Where does this come from?

        1. The back-emf of the BLDC motor is not sinusoidal, but has a shape more similar to the trapezoidal. This means, that higher frequencies are contained in the current (are you familiar with Fouriere transform?). You can see the effects.

  26. Page 5 in Assignment 2.1:
    “Car manufacturers in Germany and France state that you have to consider the energy loss caused by
    producing electric power and transport via electric network as well (see previous slide, and [2]) the
    efficiency of the electric car is reduced to ca. 28%”

    Hmmm – and whats the energy loss caused by producing fuel, starting from drilling for oil? That aspect is widely ignored in the discussion about efficiency of combustion engines.

    1. I agree – you see, that is a system thinking! You just demonstrated it. Conratulations. If I could give you extra points, you would get them.
      Well-to-wheel is a right way to evaluate the consumption. Of course that means that electric car efficiency is lower, but so is the gasoline car efficiency.
      And the new way of product energy evaluation is actually the Life cycle assesment. You have to calculate the energy for everything: production, use, maintennace and recycling/removal. Throughout the complete life cycle. It is just extremely hard to get this data…

    2. The argument is that resources like oil are there and are just converted. They can also use petrol to run their stations and plants and transfer chemically oil into petrol. Also if you transfer x liter oil from one to another place the oil amount stays the same. So all is built on an existing resource that is used again to produce more of the same resource.

      For electricity the major reasons for energy loss are:
      Energy Transport

      1-2% – Step-up transformer from generator to Transmission line
      2-4% – Transmission line
      1-2% – Step-down transformer from Transmission line to Distribution network
      4-6% – Distribution network transformers and cables

      See .

      And the biggest loss is by using thermodynamic processes to produce electric power. The efficiency of of power plants like nuclear, coal-fired or natural gas turbine is only 35%.

      So what is lead industry thinking?

      Lead German and French industry elaborated a so called perpettum mobile principle with a Noth Sea plan. Companies like MTU with partners developed small powerplants that you place on the sea ocean and where a battery that is connected to a net is placed. The controller opens the right door (based on tide) and a generator creates power. When battery is full, about 80% is loaded to the net and the process starts again. This project is delayed due to 3 reasons : (1) Brexit because BP cannot operate any more as an usual EU partner, (2) chemical and biological because the plants worked in test run in large lake constance but failed to work in North Sea due to seaweed grwing inside and destroying the plan (Need more biology and chemical reserach for sea Environments), and (3) ethics – will People allow the North sea Floor o become partly our EU power generator?

      Do teachers of biology and chemistry in school analyse sea environments and create an interest for that? We will need in future young researchers in that area.

      1. Ok, but does the oil flow through the pipeline without any help? I see a big altitude difference between Russia on producing and EU on receiving side. Surely there must be some pumps… which, I guess, are not running without using energy. And the oil also does not just come out of the ground.
        You should also know that the battery technology iss making huge advances. “Today’s average lithium-ion battery-pack price of $209 per kilowatt-hour represents the lowest in history, a 24-percent decrease from a year ago and an 80-percent drop since 2010.” [] . The project with “sea powerplants” on a oceanground is one of many, and by far not the most popular.
        When it comes to power generation, the trends are well described in Renewables are getting cheaper. And they are renewable. Something the children will also have. With oil, coal and especially nuclear we are making this planet a huge junkyard where we intend to leave them.
        Finally, the European car industry needs to step up activities in the field of electric vehicles, else it will be bypassed by Chinese and even USA. There is a growing market, the demand will be just growing due to the market demands and government regulations. I don’t claim electric vehicles are without problem and all other technologies should be scraped and forgotten. But they certainly are the future. The question is not if, but when. And to “when?” I don’t dare to give the answer.
        But I agree, students should do a research on impact of energy resources on environment and society. Such studies should be done from all aspects, ecological, sociological, …, not only technical. Just the short-time cost of energy is wrong, all the issues should be considered from a lifetime assesment viewpoint.

      2. I disagree about the efficiency of power plants; in particular there are combined-cycle power plants that almost reach 60%.
        However, it would be interesting to calculate exactly the efficiency of the whole process involving e-motors in comparison with the whole process involving internal combustion engines.
        Also, electricity has undoubted advantages:
        1) being able to be produced from renewable sources;
        2) no auxiliary transport means are needed to bring the crude oil to the refineries and the fuels to the distributors

        1. These calculations have been done, but the main thing is that you always have to observe “well-to-wheel” analysis ( A nice example is also and many more…
          I agree with the rest of your statements. But, as I always say, there is no Eierlegende Wollmilchsau. Sorry, I don’t know the comparable term in English, but we have English teacher in the audience ( – help?

          1. @Miro2
            eierlegendes Wollmilchsau: the legendary sheep with the pig’s snout laying eggs? 🙂

          2. @fulviobincolettofulviobincoletto
            Exactly, but in German it can be even a single word or two words. 🙂
            I am not German myself, but they sometimes really have nice words.
            However, “legendary” does the trick also. 🙂

  27. Hello, an input from me also.
    What I like to do is always to give a rationale. To show not just how, but also why. So – students have more motivation if they understand why to learn.
    The alternating current motor is an excellent example for trigonometric functions. You can show the frequency, amplitude, phase and even explain radians.
    As Richard already explained, the speed of the synchronous motor is proportional to the frequency. So, the motor rotates with the same frequency as the frequency of the voltage and current. So – you have a three phase current – the first phase is I1=Imax*sin(w*t), where Imax is the current maximal value – the maximal value of sinus function, t is the time and w is angular frequency – the frequency in Hz multiplied by 2*pi (here are the radians) – this is how you explain the radians, you are in troubles with degrees and you can clearly explain to students why it is so. Second phase lags for 120°, 2*pi/3 in radians (I2=Imax*sin(w*t-2*pi/3)) – you can show the concept of phase and again the radians. The third phase lags again for 120° towards the second one, 240° to the first one (I3=Imax*sin(w*t-4*pi/3)).
    In trigonometrics a nice task can follow – add all three currents. And the result is zero. But if you have a three phase system, how can it provide energy? From zero? Then you say that the voltage is also sinusoidal and for the simplicity you can use the same formula for it. U1=Umax*sin(w*t), U2=Umax*sin(w*t-2*pi/3), U3=Umax*sin(w*t-4*pi/3). Then you multiply and add: U1*I1+U2*I2+U3*I3 and the result is? Not zero! Even an additional supprise is waiting.
    I hope this also answers the question – if students are capable to solve this, it should be enough. They learn sin, cos, phase, frequency, radians etc.

  28. Always when sinx or Asin(x-120°) have 1 (peak reached) the 400 V are actuated. We have three switches, so we have 3 phase shifted sinus functions in parallel. Show the students also the picture of the 3 sinus curves on slide 16 in the above lecture. In motor control the current will be created (see where sinus function is positive) steadily until reaching the peak (in this case the amplitude of 400 V) and then decreases again.

  29. As I teach Mathematics I need some suggestion to help students to transfer what they study during my lessons in what they study in a technical scheme of an electric motor. I mean that during the morning in the classroom I explain the trigonometric functions and I create the graph of the Sinus using typical maths symbol (y=sinx, y=Asin(x-120°); then I explain that “y” can be a physical quantity like a current “I” depending on time, “x” can be “wt” (time multiplied by a pulse) and that 120° refers to a phase. Is it sufficient? How many details and deepenings are necessary? Are there some more materials useful in this context?
    Thank you

    1. And your time consideration is right. The higher the motor rpm is the shorter the period is. This allows us to calculate the speed of the rotor by the frequency.

      1. Mind that the rpm means rotations per minute – 60 rpm is 1 rotation per second = 2*pi rad/s. So 3000 rpm corresponds to 50 Hz (50 Hz * 60s = 3000 rpm). Period is 1/frequency, at 50 Hz it is 20ms.
        by the way – the length of antenas is also connected to their frequency.
        If you go to the shop ac motors will have “nominal” speed listed – and it is arround 3000 rpm / pole_pairs. One pole pair : 3000 rpm, two pole pairs, 1500 rpm etc.
        But why approximately – because in shops you can usually buy induction motors, which are asynchronous.

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