This is a technical article aimed at giving you a deep insight into the working of a Tesla. You may require a hint of technical background to fully understand the article.
The Tesla Model S is an all-electric sedan. With various norms being brought into place by leaders of the world for a cleaner planet, the push for electric cars is greater than ever. The world, whether we like it or not, is slowly inching itself to autonomous transportation. Tesla is the first big step to this paradigm shift. The Model S, Model X and the Model 3 are its answers to reduce emission and make cars desirable at the same time.
I am sure you have seen countless Go-Pro on-board reactions of people in a Tesla. The thing just Pulls.
Today, we see how all of this works.
The few, but very important electrical components of the Model S are as follows:
1) Induction Motor
3) Lithium-Ion Battery
The induction motor is made of two essential parts. The Stator and the Rotor. Tesla uses a 3-Phase 4-Pole AC Induction Motor. Firstly, there are multiple reasons for selecting an AC Induction motor over a DC Induction Motor. These Include:
1) Lower cost
2) Usage of much lesser parts
3) A simplified design of the AC Induction Motor
4) Higher reliability factor
5) Lesser shortage probability
DC Motors use brushes which could wear out over time and thus can reduce the reliability of the motor. Induction motor functions without the use of permanent magnets. Permanent magnets add weight and also get demagnetized over time.
AC Motors work by application of Alternating Current. This implies that the polarity is constantly changed and the wave oscillates. This frequency is different in different countries. In Europe, the frequency is limited to 50Hz, whereas it’s about 60Hz is the US. The rising and falling of the electromagnetic field can trigger a voltage change constantly thus creating the electrical field needed to run the car. The rotors are usually made out of Copper. The stator has coils in it. These are wound opposite to each other and energized with AC Current. These pair of coils are wound in series orientation in the stator.
Hence, an electromagnetic field of opposite charge is generated by the application of the AC Voltage. This rotates the rotor and runs the car. This is how the 2-Pole induction motor can make do without brushes and permanent magnets.
In the Tesla Model S, the rotor is made out of copper. This is done due to better conductivity. The copper rotor tends to be more expensive though. Tesla’s motor uses a 4-pole design. Here, we have 4 pairs of coils wired in series and each being 90 degrees apart, opposite to each other. The number of poles can be directly proportional to the torque that can be transmitted through the motor. Multiple sets of these are wired throughout the motor. The power is taken from 3 different sources of power. This is why we have a three-phase AC current.
The electrical skeleton remains the same across the range.
By using a three-phase current we ensure that the three different AC Sources are powering separate sets of 4 coils all the time. Hence the motor delivers high power. In the Tesla, motors are rotated at speeds of 18000 RPM. The power is instant. This is why the Tesla Model S can accelerate much faster than Internal Combustion Engine counterparts. IC Engines in general have much lesser efficiency as compared to these motors. This is credited to the uneven power delivery of the conventional powertrain.
Here we see the torque and power curve of the Tesla Model S. Since, the electric motors rotate pretty quickly, the torque curve remains more or less constant throughout. This is why the Model S accelerates faster than similarly equipped Internal Combustion Cars.
The battery pack in the Tesla model S supplies the current needed to run the motor. But, this current is DC. For the motors to be able to use this current, the DC current is converted to AC Current. The inverter is tasked with this job. The inverter also varies the AC power frequency. This is directly responsible for controlling the motor speed. The inverter also varies the amplitude of the AC Power thus directly varying the motor power output.
The cells in the battery pack are connected in both series and parallel to get the desired output. The battery needs to be cooled due to the high heat produced by it. For this reason, glycol coolant is passed through the tube. Tesla’s battery also has applied the use of multiple small cells within the battery pack. This is because usage of smaller cells can help in achieving a larger surface area and reduce thermal hot spots. The optimum temperature distribution is also achieved by using such small cells. This can lead to a higher battery life.
There are up to sixteen modules that comprise the battery pack. According to data, when the modules are all assembled, the Model S has up to 7000 cells that provide power to propel the car.
The car also has a radiator. The radiator acts as a heat exchanger and helps in reducing the temperature of the glycol that makes its way out of the battery pack after absorbing the heat produced by the cells in the battery pack. The car also uses a single speed gearbox to transmit power onto the rear wheels. This gearbox is integrated with the motor at the rear end of the vehicle.
The Tesla Semi Event last week gave us an insight into new and exciting products in the pipeline. With the new Tesla Roadster, the power is dialled all the way up to 200kW. And with acceleration claims that boggles the mind, it surely is one of the most anticipated cars of this decade. Until then, 0-60mph in 2.4 seconds will float my boat.
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If you enjoyed this article, please support us by following this website. The content is growing by the second, and is being worked on by us. All suggestions are welcome. You can check out our previous articles, by clicking here.