How hybrids work

This vehicle is actually powering those wind turbines with its own sense of self-satisfaction. Image courtesy of heliotropics.com

Hybrid cars represent the goal of auto manufacturers and consumers to have vehicles which provide the power of gasoline engines with the much cleaner energy provided by electricity. Since there are no current batteries which can provide enough extended power for a car without requiring frequent charging, a hybrid car is a compromise between gas and electricity.

Gas-powered vehicles have a powertrain where only a gasoline engine delivers power to the wheels, whereas hybrids use both a gas engine and an electric motor, which can provide power as needed. Unlike strictly electric vehicles, hybrid cars charge their batteries using power from the gas engine, as well as siphoning power which is normally lost during braking or stopping. Placing the battery and motor unit under the hood allows features like power windows and air conditioning to run solely off of electricity, and the electric motor is used solely to power the car while idling, to further reduce pollution.

The electric motor and gas engine interact to move the car at the transmission, through a series of differential gears. These gears help to compensate for different amounts of torque coming from the electrical and gas sources, so that you can switch from mostly electric power to mostly gas when accelerating from a stop. This type of system is known as a “parallel hybrid” setup since one or both sources of power can provide energy as needed. This type of system is used in most hybrid cars, such as the Honda Civic and Accord models, since it does not require a large battery, but provides for the most effective driving on the highway.

The Toyota Prius, and some other hybrids, use a variation on the parallel drivetrain called the power-split or series-parallel drivetrain. Unlike a parallel hybrid which always uses a combination of gas and electrical power, the power-split hybrid can run on solely one or the other. It accomplishes this by having the internal combustion engine responsible for moving the power train at the front of the vehicle, with the electric motor at the rear. The two power systems therefore don't need to interact through differential gears, so they can operate independently of one another. This type of system allows for a smaller gas engine to be used, since it is mostly responsible for acceleration, but the electric motor can take over entirely for steady speeds.

—Seth Berger

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