How Does an Electric Car Work?
Electric cars store energy in rechargeable batteries and use one or more electric motors to power the vehicle – no gas required! What sets BEVs (battery electric vehicles) apart from other vehicles is that they run purely on electricity. Hybrids (or HEVs, hybrid electric vehicles) and plug-in hybrids (PHEVs) still combine electric power with a gasoline engine.
Electric cars are a lot less complex than gasoline cars. They have significantly fewer moving parts – there are no oil changes, no transmission rebuilds, and even wear and tear on the braking system is reduced. So lower maintenance costs are one of the biggest advantages to going electric.
Want to learn more about how an EV works? Read on.
If you’re used to gasoline vehicles, for the sake of simplicity, think of electricity as fuel; the rechargeable battery as the fuel tank; and the electric motor as the engine.
The battery is the largest, most expensive, and most important component of an electric car. It stores the electrical energy needed by the car and powers its components. Most modern electric car batteries are lithium-ion or lithium-iron-phosphate, as they store high levels of energy while remaining relatively lightweight. Typically, a bigger battery (measured in kilowatt-hours, or kWh) means more electric range.
The battery pack is charged using an external power source – a charging plug is inserted into the car’s charge port. Think of the charging plug as the EV equivalent to a fuel nozzle at a gas station. The car’s on-board charger converts the plug’s electrical current to a format that can charge the battery, whether it’s AC (alternating current) – like the kind of power in our home wall outlets – or DC (direct current) – like the kind available at public fast charging stations.
Power Electronics and Auxiliary Systems
The power electronics are another important component in electric cars. They manage the flow of electrical energy delivered by the traction battery to the electric motor. The power electronics also manage the speed at which the motor turns and control the torque the motor produces.
The power electronics also help distribute electrical energy from the traction battery to the auxiliary vehicle systems, such as the lighting, heating, ventilation, and infotainment systems. Rather than the main battery, a separate auxiliary battery – identical to the ones found in gasoline vehicles – is responsible for powering these systems. This battery is kept charged by the DC/DC converter, which converts high-voltage DC power from the traction battery into the low-voltage DC power required to power the auxiliary systems.
The vehicle thermal management system also should be mentioned. It helps ensure that the vehicle’s batteries are operating within the correct temperature range. When an electric car accelerates, the battery’s electrical energy is discharged and heat is generated; since acceleration is often the primary method of discharging the battery, without a proper cooling system, the battery would quickly overheat.
How Electric Car Motors Work
Using electrical energy from the battery pack, the electric motor converts that energy into mechanical energy, which drives the wheels. Most electric vehicles don’t have a transmission with multiple speeds, so there are no gears to shift. Depending on the number and placement of the motors, an electric car can either be front-wheel drive (FWD), rear-wheel drive (RWD), or all-wheel drive (AWD). Some electric cars even have a motor at each wheel!
Most electric motors have two main components: the stator, which is the stationary part of the motor, and the rotor, which is the moving part of the motor. The stator is built by stacking thin, laminated rings and forming them into a hollow cylinder; slots in the hollow interior allow conducting wire to wrap around and shape the coils.
The rotor has a core, conducting rods, and two end rings. Thin, laminated discs are stacked, forming them into a solid cylinder with a rod running through the center. On the exterior of the rotor core, there are slots like on the stator core that run diagonally across the cylinder instead of parallel to the rod in the center.
Along these diagonal lines of the rotor core, conducting rods are inserted, and end rings are placed on both sides of the core to lock the rods in place. The rotor slides into the hollow stator core, and two end bells are placed on either side of the rotor core’s center rod.
As electrical energy is supplied to the motor, the coils produce a rotating magnetic field that induces current through the connecting rods of the squirrel-cage rotor, which makes the rotor spin. This spinning rotor creates the mechanical energy needed to turn the wheels of the car.
One of the cool things about electric motors is the “regenerative braking” function. When you take your foot off the accelerator (not gas!) pedal, the motor acts in reverse and converts the car’s forward motion back into electrical energy. The energy is then sent back to the battery –recovering energy that would otherwise be wasted. It won’t come close to fully charging your electric car’s battery, but regenerative braking does help give you a little bit of extra range.