As the automotive industry continues to shift away from fossil fuels, electric vehicles have become more popular and accessible for the average consumer. Unlike traditional automobiles, these vehicles use alternating electromagnetic fields to rotate a shaft. However, there are a variety of engine types, including AC and DC engines, with varying efficiencies.
Leading electric vehicle manufacturers, such as Tesla, Chevrolet, and Nissan, use both AC and DC electric engines to operate their vehicles. However, AC engines are generally considered better and more efficient than older DC engines. This comes at an added cost though, pushing many consumers to purchase more-affordable DC vehicles.
To better understand the mechanics of an EV engine, continue reading below. This guide will discuss how electric vehicles work and explore the various types of engines used to power these vehicles. This includes brushed and brushless DC engines, as well as induction and synchronous AC engines.
How Does an Electric Vehicle Work?
Traditional automobiles work by combusting fossil fuels, such as gasoline or diesel, to produce energy. That energy is then converted through a series of pistons into a crankshaft that rotates and spins the wheels. Rather than relying on a non-renewable energy source, electric vehicles (EVs) convert the energy stored in a battery into electricity. This electricity is then used to power an electric motor that turns the wheels.
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The electric motor in an EV is significantly different than the internal combustion engine found in traditional automobiles. Rather than relying on a series of pistons, an electric motor uses a series of electromagnets and coils to create rotational force. The engine itself is made up of two main parts:
- Stator: The stator is the stationary part of the engine and is typically made up of either copper or aluminum wire. This wire is coiled around a series of magnets, which are usually made up of rare-earth metals, such as neodymium. The strength of the magnets creates a magnetic field, which is then used to rotate the rotor.
- Rotor: The rotor is the rotating part of the engine and is made up of a series of electromagnets. These electromagnets are powered by the electricity stored in the vehicle’s battery. As the electricity flows through the coils, it creates a magnetic field that interacts with the field created by the stator. This interaction creates a rotational force that turns the wheels of the vehicle.
All EVs rely on these two parts to generate rotation force, regardless of the type of engine. The main difference between engine types is how the energy is converted from a battery and at what voltage.
Types of Electric Vehicle Motors
There are a variety of electric vehicle motors available on the market, each with its own set of unique advantages and disadvantages. While some engines use AC currents, others use DC currents and, for those who have forgotten from physics class, this means they use varying directional flows. With AC electricity, the current repeatedly changes direction, whereas DC currents flow in a single continuous path.
The first type of engine is the DC motor, which was the first type of electric motor ever invented. These motors were first used in the early 19th century and continue to be used today. In fact, many small appliances, such as hair dryers and vacuum cleaners, still rely on DC power, which flows in a single, continuous path.
These motors are typically less expensive and easier to maintain than their AC counterparts. Additionally, DC motors are typically smaller and lighter, making them ideal for smaller electric vehicles.
Brushed DC Motors
Brushed DC motors were the first type of DC motor ever invented and are now the most common variety you’ll find. As suggested by their name, these motors are powered by a direct current and use a set of carbon brushes to transfer that current to the rotating armature—a set of coils that are wrapped around a central shaft.
As the current flows through the armature, it interacts with the magnetic field created by the stator to create a rotational force. This force is then transferred to the wheels of the vehicle, propelling it forward.
Brushed DC motors are typically cheaper and easier to maintain than their brushless counterparts and they tend to be smaller and lighter, making them ideal for smaller electric vehicles. However, brushed DC motors are not as efficient as brushless DC motors and typically have a shorter lifespan.
Brushless DC Motors
Brushless DC motors were first invented in the 1960s. These motors are also powered by a direct current but, unlike brushed motors, they use a set of electromagnets to transfer current into the armature rather than a set of carbon brushes. Then, as the current flows through the armature, it interacts with the magnetic field to create rotational force.
As with any other electric engine, this force is then transferred to the wheels of the vehicle, propelling it forward. Brushless DC motors are more efficient than brushed DC motors, however, they are also more expensive. Additionally, brushless DC motors are typically larger and heavier, making them less ideal for smaller electric vehicles but a smart choice for larger cars.
The second type of electric vehicle motor is the AC motor, which uses an alternating current rather than a direct current. These motors were first invented in the late 19th century and, like DC motors, they continue to be used today. In fact, many large appliances, such as washing machines and refrigerators, still rely on AC power, which flows in a repeating pattern.
AC motors are typically more expensive than DC motors, however, they are also more efficient. Additionally, AC motors are typically larger and heavier, making them less ideal for smaller electric vehicles but a smart choice for a larger car.
Induction AC Motors
An induction AC motor is a three-phase engine designed to maximize speed and energy efficiency. These engines generally operate at around 240 volts and can also be used to regenerate energy by using the motor’s resistance to slow the vehicle down. The three-phase current flowing through the armature interacts with the magnetic field to create rotational force. This force is then transferred to the wheels to propel the vehicle forward.
Although a handful of Tesla vehicles operate using DC engines, the majority of modern Teslas are powered by energy-efficient induction AC motors that run for around 500 miles on a single battery charge. They are obviously more expensive but their power and output speak for themselves.
Synchronous AC Motors
A synchronous AC motor turns at exactly the same speed as the supply frequency. The speed of the synchronous AC motor is determined by the number of poles it has, the number of poles being the number of current or voltage wave peaks in one complete revolution of the motor. These motors are less common than induction motors but they are still used in a variety of EVs.
Although electric vehicles have become more affordable in recent years, models powered by highly efficient and powerful induction AC engines are still above many consumers’ budgets. Nevertheless, these engines are without a doubt the best type of engine for an electric vehicle.