The era of electric mobility began a few years ago and is already a tangible and established reality, with electric motors powering eco-friendly cars on the roads, thanks to coordinated global efforts to reduce emissions and electrify the planet. There are several models of vehicles propelled by an electric motor that we see moving around smoothly in city traffic. Although they may seem very similar in operation, internally, the various types of electric motors hide differences that can be decisive in evaluating the most suitable model to choose.
The concept of the electric motor dates back several centuries, but it was only in the 19th century that we learned to harness the forces of nature and made significant and meaningful strides in the development of these technologies. Various variants of electric motors were introduced and perfected to meet the specific needs of different applications, often in the industrial field. This process led to the differentiation of electric motors used in automobiles, offering a wide range of choices for sustainable mobility.
The two main types of electric motors are alternating current (AC) motors and direct current (DC) motors. AC motors are widely used due to their efficiency and flexibility, while DC motors have proven to be suitable for many applications, thanks to their ease of control. In addition to these, synchronous and asynchronous electric motors have emerged, each with its own peculiarities and specific advantages.
Alternating Current (AC) Motors
AC motors are widely used in electric cars for their efficiency and flexibility. Comprising a rotor and a stator, both powered by alternating current, they offer higher efficiency thanks to their ability to regulate the frequency and voltage of the power supply. Furthermore, AC motors can provide high power at low speeds and offer precise control over speed and torque. This flexibility makes them suitable for a variety of automotive applications. In particular, permanent magnet synchronous motors (PMSM) are very popular for their high performance and improved efficiency. Some electric car models that use AC motors include the Tesla Model S, Audi e-tron, and Porsche Taycan.
Direct Current (DC) Motors
DC motors are one of the earliest forms of electric motors developed and are still widely used in modern electric cars. They convert electrical energy supplied by a battery into rotary motion. DC motors are known for their simplicity of construction and control.
This control is achieved through electronic control systems like speed controllers. Thanks to this regulation capability, DC motors are suitable for various applications and offer high efficiency at various operating regimes. Due to this, DC motors, however, require a more complex control system compared to AC motors. Some examples of electric cars using DC motors include the Nissan Leaf and BMW i3.
Synchronous Electric Motors
Synchronous motors are a variant of alternating current motors that offer higher efficiency and better performance. By maintaining precise synchronization between the supply frequency and rotational speed, these motors generate constant power and high efficiency. Synchronous motors are often used in high-performance electric cars as they can provide high torque at any rotational speed. Additionally, synchronous motors are known for their efficiency even at partial loads. However, they require phase control to maintain synchronization and may require the presence of permanent magnets or excitation windings to generate the required magnetic field. Some examples of cars with synchronous motors are the Tesla Model 3 and the Jaguar I-PACE.
Asynchronous Electric Motors
Asynchronous motors, also known as induction motors, are another common option used in electric cars. They harness the principle of electromagnetic induction to generate rotary motion. Asynchronous motors are known for their robustness, reliability, and ability to operate in a wide range of load conditions. They do not require the use of permanent magnets but may require an external starting device, such as an inverter. Asynchronous motors are often used in automotive applications where high torque at low speed is required, such as in commercial vehicles and electric buses. Cars that have implemented asynchronous motors include the Chevrolet Bolt EV and the Renault Zoe.
Starting with the Right Motor
Choosing the type of electric motor is crucial to ensure optimal performance and a satisfying driving experience. Each type of motor has specific performance and limitations that must be carefully evaluated and considered when choosing the next electric vehicle for your garage. A commercial vehicle used for city deliveries will have different needs than those of occasional car users. Understanding these differences helps make an informed choice that can meet the needs of your everyday activities.