How electric vehicles work

How electric vehicles move

EV's are like an automatic car. They have a forward and reverse mode. When you place the vehicle in gear and press on the accelerator pedal these things happen:

• Power is converted from the DC battery to AC for the electric motor
• The accelerator pedal sends a signal to the controller which adjusts the vehicle's speed by changing the frequency of the AC power from the inverter to the motor
• The motor connects and turns the wheels through a cog
• When the brakes are pressed or the car is decelerating, the motor becomes an alternator and produces power, which is sent back to the battery

AC/DC and electric cars

AC stands for Alternating Current. In AC, the current changes direction at a determined frequency, like the pendulum on a clock.
DC stands for Direct Current. In DC, the current flows in one direction only, from positive to negative.

Battery Electric Vehicles

The key components of a Battery Electric Vehicle are:

• Electric motor
• Inverter
• Battery
• Battery charger
• Controller
• Charging cable

Electric motor

You will find electric motors in everything from juicers and toothbrushes, washing machines and dryers, to robots. They are familiar, reliable and very durable. Electric vehicle motors use AC power.

Inverter

An inverter is a device that converts DC power to the AC power used in an electric vehicle motor. The inverter can change the speed at which the motor rotates by adjusting the frequency of the alternating current. It can also increase or decrease the power or torque of the motor by adjusting the amplitude of the signal.

Battery

An electric vehicle uses a battery to store electrical energy that is ready to use. A battery pack is made up of a number of cells that are grouped into modules. Once the battery has sufficient energy stored, the vehicle is ready to use.

Battery technology has improved hugely in recent years. Current EV batteries are lithium based. These have a very low rate of discharge. This means an EV should not lose charge if it isn't driven for a few days, or even weeks.

Battery charger

The battery charger converts the AC power available on our electricity network to DC power stored in a battery. It controls the voltage level of the battery cells by adjusting the rate of charge. It will also monitor the cell temperatures and control the charge to help keep the battery healthy.

Controller

The controller is like the brain of a vehicle, managing all of its parameters. It controls the rate of charge using information from the battery. It also translates pressure on the accelerator pedal to adjust speed in the motor inverter.

Charging cable

A charging cable for standard charging is supplied with and stored in the vehicle. It's used for charging at home or at standard public charge points. A fast charge point will have its own cable.

EV versus ICE

The most significant difference between ICE (Internal Combustion Engine), BEVs and PHEVs is found in the powertrain, the components that generate motive (moving) power and deliver it to the wheels to move the car.

• ICE vehicles burn fuel (usually petrol or diesel) that releases heat to move parts of the engine and other components that deliver power to the wheels. The ignition starts this combustion process.
• BEVs use power stored as electricity in rechargeable batteries and deliver it via one or more electric motors to the wheels.
• PHEVs have both ICE and electric components, along with controls that manage the balance of electric and ICE power used while driving.

How it works

Through the ignition and combustion of a 15:1 air-fuel mix, the ICE engine converts thermal energy into mechanical energy and emits waste exhaust gases in the process. Improvements in efficiency and evolving emission standards, ICE technology has not changed much in the last 100 years.

There are hundreds of moving parts with tight tolerances that must work together to keep the combustion engine running. When the combustion process starts you can hear and feel the vibrations in the vehicle caused by the mechanical and hydraulic systems.

ICE engines produce power in a limited speed range and use gears to maintain acceleration. Fuel keeps burning as long as the engine is switched on, even when the car is idling.

Electrical powertrains convert electrical energy (stored in the battery), into mechanical energy which turns the motor, rotating the wheels. EVs have 90% fewer moving parts than ICE vehicles.