As with thermal cars, the engine of an electric car can be of different types and each of them will offer certain qualities that will make it more suitable for one model or another. Let’s meet them.
Did you think that all motors for electric cars were the same? Furthermore, did you think that all electric motors are of the same type, regardless of whether they are used for cars, industrial machinery or another type of application?
The answer to these two questions is No.. And we are going to tell you what it is due to and what are the different types of electric motor that you can find in the plug-in car market.
Synchronous or asynchronous motor
The first distinction, but not the only one, is the one we have to make between the two large groups of electric motors that exist on the market. We are talking about synchronous or asynchronous motors, which we will talk about in depth in this article in our dictionary.
But, broadly speaking, what you want to know now is this. The asynchronous motors are those in which the magnetic field is always a few degrees ahead of the rotor. Instead, in the synchronous motors both the rotor and the magnetic field rotate at the same speed and in a synchronized manner.
This is how synchronous motors work.
Wait, you don’t know how an electric motor works? Don’t worry, we will tell you about it in detail in this article.
In general terms, a synchronous motor is cheaper, generates less vibrations, is efficient and also reliable. But the asynchronous motor also has its advantages, as it is lighter and smaller, allows great speed control, offers higher performance and is more resistant to overload.
Types of electric motors for cars
Although we have already separated between synchronous and asynchronous motors, in reality within each of these types there are, in turn, several more types that we have to talk about. They are the following:
- Synchronous reluctance motor
- Permanent Magnet Synchronous Motor
- Asynchronous or induction motor
Synchronous reluctance motor
The reluctance motor is a synchronous motor provided with a rotor with metallic parts. In this type of motor, current is switched through coils. These coils are what create a rotating magnetic field, which causes the rotor poles to attract each other and generate torque.
They are motors with the capacity to offer high levels of torque and power, especially at high speeds, but are also robust and economical. On the other hand, they are not very efficient at low revolutions, are noisier and have undulation in the delivery of torque (it must be corrected electronically).
Permanent Magnet Synchronous Motor
This type of motor can be radial or axial flow, something that will depend on the position of the induction magnetic field (perpendicular to the axis of rotation of the rotor or integrated in the wheels).
By having permanent magnets, this type of motor does not need to induce a magnetic field, so it does not suffer from losses in the rotor and can be smaller and more compact. Furthermore, it is light, quiet and very efficient at low revs.
On the other hand, it is quite expensive and its environmental impact is high due to the permanent magnets, which can also become demagnetized over time. Likewise, they need additional mechanisms such as position sensor, starting mechanism and electronic controls.
There is a brushless variant, in which the magnets are placed on the rotor and are sequentially powered from each phase of the stator. It is often used in hybrid cars and is very solid, quiet and maintenance-free. But they are also expensive and not very powerful.
induction motor
The induction motor or asynchronous motor is one in which the electric current that passes through the stator winding is what generates the magnetic field.
This motor runs on alternating current (AC). If it is single-phase, the magnetic field will be alternating. But if it is three-phase, then what will be produced is a rotating magnetic field called RMF.
This motor is used because it is simple, cheap and generates little noise and vibration, qualities that make it reliable and efficient. However, this causes the induced current to generate losses and heat. It is also not a light and compact engine.
How many motors does an electric car have?
Electric cars allow numerous variables in this section, specifically as many as there are wheels on a car.
Currently, in the market we can find electric cars with one, two, three and even four motors. The most common is to find a single motor to move one of the axes, although the presence of two motors for each of the axes has become very widespread in the market and there are quite a few models that incorporate them in their top-of-the-range versions.
But we also have cases with three electric motors, such as the case of the Audi e-tron S, which uses two of them on the rear axle. And finally, some of the most advanced sports cars or future high-end models already have four electric motors, one for each wheel.
Examples of this are the Rimac Fridgethe Nio EP9, the Rivian R1T or the future Mercedes EQG.