How do Electric Cars work?
Hey friends, Happy Wednesday!
Let’s look at how Electric cars work this week. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for your food, etc. Let's jump in!
Figure 1: Components of an Electric Vehicle. Source: pcmag
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How do Electric cars work?
Step 1: Charging the battery pack
Figure 2: Battery pack (left). Battery module (middle). Battery cell (right)
An external source of power (charging station) is used to charge the battery pack placed in your electric vehicle through a charge port. The battery pack is a large set of small lithium-ion batteries. We do not use a small number of large batteries as they do not help us in regulating temperature and have shorter battery life. And lithium-ion battery operates by producing only DC current, similar to your mobile phone’s.
Small cells are packed together to form a battery module. Multiple modules are put together to form a battery pack.
Step 2: Powering the electric motor
Figure 3: Inverter in a Tesla
The electric induction motor uses AC current to operate but the battery pack provides only DC current. So how do we power the motor to move the electric vehicle around? Here comes the Inverter, the brain of the vehicle!
The inverter not only converts the DC current supplied from the battery pack to AC current for the motor but also adjusts the frequency of the current based on how the user presses the accelerator pedal. Let me go a little deeper. The more you press the accelerator pedal, the more the inverter increases the frequency of the AC current supplied to the motor. This makes it rotate at a faster speed.
It can also increase or decrease the power or torque of the motor by adjusting the amplitude of the signal.
Step 3: Turning the wheels
Now, we have reached a point where the electric motor is supplied with electrical energy. It converts it into mechanical energy. Pretty straightforward from here like in a gasoline car.
The mechanical energy from the electric motor is basically a rotating shaft, which is connected to the drive wheels using a gearbox. Gasoline cars have a differential to rotate the wheels of your car at different speeds (performing a turn in a car won't be possible if the wheels move at the same speed - one has to move faster and the other has to move slower). Likewise, an electric vehicle uses a differential as well to move the electric vehicle around! It has no fuel pump, fuel tank, exhaust, or tailpipe like the cars that run on gasoline though.
This is the basic structure of how an electric vehicle works!
Question of the week
Why do we use Lithium-ion batteries for an electric vehicle specifically, and not any of the other types? Reply to this email with your thoughts and we can have a discussion. I’ll answer this next Wednesday!
Thank you for reading!
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
