All-electric vehicles (EVs), also referred to as battery electric vehicles, have an electric motor instead of an internal combustion engine. The vehicle uses a large traction battery pack to power the electric motor and must be plugged in to a wall outlet or charging equipment, also called electric vehicle supply equipment (EVSE). Because it runs on electricity, the vehicle emits no exhaust from a tailpipe and does not contain the typical liquid fuel components, such as a fuel pump, fuel line, or fuel tank. Learn more about electric vehicles.
Key Components of an All-Electric Car
- Battery (all-electric auxiliary): In an electric drive vehicle, the auxiliary battery provides electricity to power vehicle accessories.
- Charge port: The charge port allows the vehicle to connect to an external power supply in order to charge the traction battery pack.
- DC/DC converter: This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.
- Electric traction motor: Using power from the traction battery pack, this motor drives the vehicle’s wheels. Some vehicles use motor generators that perform both the drive and regeneration functions.
- Onboard charger: Takes the incoming AC electricity supplied via the charge port and converts it to DC power for charging the traction battery. It also communicates with the charging equipment and monitors battery characteristics such as voltage, current, temperature, and state of charge while charging the pack.
- Power electronics controller: This unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces.
- Thermal system (cooling): This system maintains a proper operating temperature range of the engine, electric motor, power electronics, and other components.
- Traction battery pack: Stores electricity for use by the electric traction motor.
- Transmission (electric): The transmission transfers mechanical power from the electric traction motor to drive the wheels.
What is an electric motor?
An electric car motor works using a physical process developed at the end of the 19th century. This consists of using a current to create a magnetic field at the fixed part of the machine (the “stator”) whose displacement sets a rotating part (the “rotor”) in motion. We’ll take a closer look at these two parts, and more, further down.
The principle of an electric motor
What’s the difference between an engine and a motor? The two words are often used interchangeably. It’s important, therefore, to differentiate them right from the start. Despite being employed as almost synonymous nowadays, when it comes to the automotive industry, a “motor” refers to a machine that converts energy into mechanical energy (and therefore motion), while an “engine” does the same thing, but specifically using thermal energy. When talking about converting thermal energy into mechanical energy, we therefore mean combustion —not electric.
In other words, an engine is a type of motor. But a motor is not necessarily an engine. With electric vehicles, because the mechanical energy is created from electricity, we use the word “motor” to describe the device that makes the electric vehicle move (aka traction).
How does an electric car motor work inside an EV?
Now that we know that we’re talking motors, not engines, how does a motor work inside an electric vehicle?
These days electric motors can be found in numerous everyday devices. Those that use direct current (DC) motors have quite basic functions. The motor is connected directly to an energy source and its rotation speed depends directly on the intensity of the current. While easy to produce, these electric motors don’t meet the power, reliability or size requirements of an electric vehicle, although you may find them powering the windshield wipers, windows and other smaller mechanisms inside the car.