Welcome to the world of electric vehicles (EVs) – where cars
use electricity and battery storage to get around, replacing gasoline and
reducing air pollution in an effort to minimize the human population’s carbon
footprint! EVs are a booming trend in the auto industry, particularly as
consumers look to make more environmentally conscientious decisions and realize
some of the unique benefits EVs offer. With their increasing popularity, it’s
important to know what EVs are and why they’re taking off – so let’s start with
What is an EV?
Electric vehicles, as their name suggests, use electricity
as a power source rather than gas, therefore minimizing or entirely eliminating
gasoline engines and the greenhouse gas emissions that result from their
operation. There are two main types of EVs: all-electric vehicles (AEVs) and
hybrid electric vehicles (HEVs). Let’s dive into this alphabet soup!
vehicles run solely on electricity. They are all-electric, all the time. AEVs
have zero tailpipe emissions, unlike internal combustion engine vehicles (ICEVs),
and use electric motors for propulsion. There are two types of AEVs, which
differ in terms of fuel source and how they’re refueled:
vehicles (BEVs) are 100% powered by electricity that’s stored in a battery.
BEVs are refueled using the electric grid by plugging into EV chargers to
recharge their batteries – just like how you’d recharge your cell phone (only
with a lot more power!). BEVs have the largest batteries of all types of EVs
and are the most popular type of AEV, with a number of models currently on the
market and many more being made available by automakers in the coming years.
electric vehicles (FCEVs) are powered by electric motors and fuel cells,
which convert hydrogen into electricity through a chemical reaction. FCEVs store
hydrogen in an onboard tank and are refueled at hydrogen stations. FCEVs are
not very common in the US, though some models are available and some fleets
have adopted them.
vehicles differ from AEVs because they combine the battery of a BEV with the
gas-powered engine of an ICEV – hence the “hybrid” moniker. There are two main
types of hybrid vehicles, which primarily differ in terms of battery size and
how their batteries are charged.
hybrid electric vehicles (PHEVs) typically operate first in “all-electric
mode,” when the battery has the most charge, and then switch over to using the
combustion engine when needed. Drivers refill the battery by plugging it in at
an EV charger, just as they would for a BEV; but drivers must also refill their
gas tanks at gas stations. PHEVs offer drivers the ability to go all-electric
(and tailpipe emissions-free!) for short trips, under 50 miles, with the
flexibility of the gas engine for longer trips. Most trips – i.e., a daily
commute for work or errands – fall within the all-electric distance. PHEVs have
been seen as a “transition vehicle” to introduce people to the nuances of
electric transportation while retaining access to existing gasoline
infrastructure. PHEVs typically have smaller batteries than BEVs and smaller
gasoline engines than ICEVs. In addition to extending beyond the vehicle’s
all-electric range, the combustion engine may also be utilized for high-power-draw
activities, such as fast acceleration or when passengers turn on the heat or
air conditioning, which can put too much demand on a PHEV’s small battery.
electric vehicles (HEVs) use regenerative braking to recharge. Their
batteries are fully self-efficient and do not rely on electricity from the
grid, but drivers must still refill their gas tanks at gas stations. The small
batteries of HEVs can provide some all-electric, low-speed range, additional
power during acceleration, and a way to reduce idling emissions.
How do EVs work?
The diagram above helps explain the mechanics behind how EVs
work. All EVs need electricity, to some extent, for power. To get this
electricity, many EVs must plug in at a charging station. The diagram above
shows the plug-in connection above the front driver-side tire – the Charge Port
nozzle looks like it is for gas, but that’s actually where the car plugs in to receive
power to charge its battery. The electricity then passes through the Onboard
Charger before being stored in the Traction Battery Pack, which sits under the
vehicle. The Electric Traction Motor converts electricity from the battery to
move the car, while the Power Electronics Controller, DC/DC Converter, and
Thermal System all work to ensure that power is distributed to the equipment
that needs it and that the battery is safe.
Now, let’s imagine this diagram were of a PHEV – what would
we need to add to it? The answer includes essential parts of an ICEV: an internal
combustion engine, gas tank, and fuel nozzle; in addition, the battery size
would shrink quite a bit to make room for the added parts. Once a hybrid runs
out of electric energy, the transmission begins transferring energy from the
internal combustion engine, which is fueled by gasoline.
Similar to above, if we were to imagine the diagram
represented an HEV, what changes would be made? Like the PHEV, the HEV diagram
would require the addition of a fuel tank but would not need a charge port. This
is where regenerative braking comes in. The electric generator in HEVs transforms
the energy produced from braking into electric power that the car can reuse to
drive; the generator then transfers this energy back into the battery for
storage until it is needed.
In our next article, EVs 102, we will be diving into the
pros and cons of EVs. Here’s a sneak peek: