Electric vehicles have become rather popular in the last few months. In contrast to internal combustion engine vehicles that run on gas, electric vehicles (EVs) run on the electrical energy stored in their battery packs to power their engines. Moreover, EVs have fewer moving parts compared to gas vehicles and are usually more low-maintenance. The downside though, is that they cost more than the average vehicle.
EV batteries usually consist of groups of lithium-ion batteries laid out in large banks on the bottom of the vehicle, known as traction batteries. The battery is charged by electricity from the grid via a charging station or by being plugged into a home power socket. The energy the battery can hold depends on its capacity, which is measured in kilowatt-hour (kWh).
Unlike the energy from a typical wall outlet in your home, batteries produce direct current power. To generate rotational force, alternating current power is needed. The design of the motor in EVs solved this problem.
The Mechanics of the Motor
EVs use electromagnets inside the motor fueled by the battery to create rotational force. The two sets of magnets are charged so that their polarity is the same and repels one another. This force makes the wheels spin, which moves the car forward and backward, and that turns the shaft.
The polarity of the magnets has to change as the shaft turns to maintain a constant state of repulsion between the magnets. If there is no polarity change, the magnets will eventually attract each other. The motor contains a device called an inverter to keep flipping the polarity.
An inverter can quickly change polarity to keep the rotational force going. The current sent to the motor can be changed by the driver. The higher the frequency, the more the polarity flips, generating more rotational force. In addition, a DC converter is used to direct power to other systems such as heating and lighting.
So What's the Big Deal?
Electric vehicles do not burn fossil fuels, which means that they do not emit harmful gasses. Their range of EVs is comparable to a gas vehicle on average. When compared, the price to power an EV is about half what it costs to power a gas vehicle. Although EVs still have some kinks to work out, they are a large part of the movement to find greener alternatives.