Progressively attracting the greatest attention in the automotive sector, new cars and their electric motors seem like the future choice over mobility. High-tech, more advanced, intelligent vehicles … and with very different components from those seen so far. But, how is an engine of these characteristics? What is its operation?
The electrified car is here to stay. And not because it is something really new (the first emerged 200 years ago), but because everything indicates that they will be the most convenient for the days to come, for a sustainable climate and a more ecological environment. More and more traditional manufacturers have one or more in their range, drawing the curiosity of others who have not yet done so. Characterized by their electric motors and batteries , they work in a simple way.
Basic fundamentals of an electric motor
The most differentiating characteristics that we have with those of combustion cars are seen in that these electric motors are silent, efficient, rarely need to be repaired and offer emission-free driving. Another decisive advantage is that electric vehicles are more efficient in resources than those powered by combustion engines. If we add the fact that much of the electricity required is generated from renewable energy, we will never look back.
That is why these are made as a safer alternative to have a new vehicle. And their propellants and their operation have a lot to do with it. Where, thanks to the different pieces of which it is composed, it allows a very particular execution and march .
If we look at the mechanics itself, inside we can see that its operation is much simpler than that of a heat engine. Unlike engines that run on fuel in which the energy is given by explosion, in these the movement occurs thanks to electromagnetic interactions . Thus, this powertrain is responsible for transforming the electrical energy that it absorbs through its terminals into mechanical energy, transmitting this energy to the wheels and thus allowing the movement of the vehicle.
Elements of an electric motor
With the great advantage of having fewer moving parts, its simple and reliable operation is what energetically distances it from a conventional one. For example, it occurs in that this type of propellants do not carry cooling systems, as well as a common gearbox. In this way, and although not all electric car models are the same, they do have some parts or general elements within their manufacture.
Based on electromagnetic rotation, it consists of the use of two magnets that reject or attract each other, depending on the alignment of their poles. That orientation will be the one that generates a forward or backward movement. In the case of electric motors for cars, electricity is used to create magnetic fields. The parts of an electrical system are divided into several large groups.
- Batteries They are those that store the energy coming from the charger in the form of direct current. These batteries are responsible for feeding the entire electric car through their stored energy. In electric cars that have an alternating current motor, the battery is connected to an inverter.
- Charger. It is responsible for absorbing electricity alternately directly from the external network and transforms it into direct current and stored in the battery.
- Electric regulator. It is the system composed of several electrical and electronic subsystems called inverter, rectifier and transformer. Thanks to them, it is able to manage the current flows between the batteries and the motor in both directions. Both when the engine pushes the car and when the engine recharges the batteries, acting as a generator during retention or smooth braking.
- Transformers In charge of converting internal current into direct current. Allows to be stored by batteries.
- Inverters : They transform direct current into alternating current, when it comes to alternating current motors.
- Controllers : They check the correct operation for efficiency and safety, as well as regulate the energy that the motor receives or recharges.
Phases and energy management
As we have seen in the previous section, there are several types of elements that make these electric motors work correctly for their subsequent mobility in cars. However, each of those types works with a power management that is the same for all. We see it, in particular, with what are its phases of use . That’s where both the acceleration and deceleration phases come in.
Both controlled by the driver himself, they allow energy to be reversed to create movement or, where appropriate, to convert kinetic energy (movement) into electrical energy to recharge the battery.
- Acceleration phase . The electrical energy in the form of direct current passes from the battery to the converter, which is responsible for modifying this electrical energy from direct current to alternating current . This reaches the motor that, by means of the previously explained system, moves the rotor which ends up becoming the movement of the wheels.
- Deceleration phase . Here, everything starts on the wheels. These are in motion after completing the acceleration phase, that is, when we lift our foot off the accelerator. The electric motor generates resistance and converts the kinetic energy into alternating current, which again passes through the converter that converts it into direct current and, in turn, is stored in the battery . This process also occurs when the regenerative braking of the electric car acts.
What types are there
Together with the battery, the motor forms the most important pair of all the components required by an electric vehicle. Efficiency, autonomy and performance depend on it . There are different types of electric motors on the market, consisting mainly of three fundamental parts: stator, rotor and the casing that surrounds them.
Depending on their power supply by alternating or direct current and their architecture, they are divided into other categories (asynchronous motors, synchronous with permanent magnets, brushless with permanent magnets and synchronous motors with switched or variable reluctance).
- Stator . It is the fixed part of the machine. It can be from electromagnets to magnetic plates, and it does this by housing the rotor, the moving part and the other important part of the same.
- Rotor . The moving part contains a fixed magnetic field. This rotates in the stator draws the fixed magnetic field of the rotor and makes it rotate. This, in turn, by means of a series of gears, allows the wheels of the electric car to rotate and, consequently, to generate movement.
- Housing .
Asynchronous
We distinguish two main types of electric motors in the supply of this type of car. On the one hand there are those that are direct current. They are identified by the acronym in English DC. On the other hand, there are alternating current motors, also identified by their acronym in English AC. From there, the subtypes come in. The first of these are asynchronous motors.
This alternating current motor is also known as an induction motor . On a mechanical level, its great difference with respect to the rest is that the rotation of the rotor does not occur at the same speed as the magnetic field produced by the stator. On a practical level, this subtle feature does make important differences. Asynchronous motor electric cars are cheaper, very quiet and offer perfect driving efficiency . They basically consist of the rotor, which can be a squirrel cage or winding, and a stator, where the inductor coils are housed, which are three-phase and 120 degrees out of phase with each other.
Synchronous with permanent magnets
This electric car propeller is also alternating current. It offers a constant speed of rotation and this time it is even between rotor and stator. In turn, it is available in two formats, with radial flow (the most used) and with axial flow . The difference is in the position of the induction magnetic field.
In either case, cars that mount these permanent magnet synchronous electric motors offer excellent performance, maximum speed control, as well as low noise and minimal vibration. The production of these engines makes the final cost of the vehicle more expensive. However, it is the most widespread modality among hybrids.
It incorporates, embedded in its rotor, magnets composed of rare earths , such as dysprosium, gadolinium or neodymium. These are elements, mostly imported from China, scarce, expensive and difficult to recycle. From this, the thrusters need neither external excitation nor brushes to generate the magnetic field in the rotor and make it rotate. They are more compact and simple.
Brushless permanent magnets
They are often used in hybrid vehicles. They work through permanent magnets located in the rotor and that are fed sequentially from each phase of the stator. Their price is high and they have little power, but they do have advantages such as their high robustness, zero noise and that they do not need maintenance. They are commonly known as ‘brushless’.
Today, thanks to electronics, they are very advantageous, since they are cheaper to manufacture, weigh less and require less maintenance, but their control is much more complex. This complexity has been practically eliminated with ESC electronic speed controllers.
Synchronous with switched or variable reluctance
Variable reluctance synchronous motors is the name given to an electric motor of the AC type (which works with alternating current). The difference is that its operation is based on variable reluctance. This behavior takes place by means of a toothed rotor that is aligned with the stator poles. The poles of the rotor are attracted by the magnetic field and create a pair that feeds it.
They are thus quite impressive electric motors in cars, with a high torque that, however, are very cheap and do not offer great power . Its main value is in the efficiency offered by the engine, which is why many manufacturers choose it as a priority for some of their models. Among its advantages, this type of thruster has a very high dynamics thanks to its low inertia, as well as a greater precision control of speed / torque.
