Series, Parallel, and Power-Split Hybrid Drives
There are many different hybrid models on the market. Some are plug-in hybrids that require an outlet to charge, while others are simple hybrids that use gasoline power instead.
Not only are there different types of hybrids, but there are also different types of powertrains for hybrids: series drive, parallel drive, and power-split (also called series-parallel drive).
A hybrid that doesn’t have an internal combustion engine at all, some vehicles, such as hydrogen fuel cell vehicles and battery/electric cars, require a different powertrain assembly to function. For more information on these powertrains, see below.
Series Drive
Standard drive is found in many standard hybrid vehicles. In a series drive configuration, the wheels receive power only from the electric motor. To make this possible, the engine is powered by a generator or a battery pack.
The vehicle’s gasoline engine powers the generator, which in turn powers the electric motor. In addition, the battery is charged by a generator.
Vehicles with serial drive often have so-called regenerative braking. In this braking system, the battery is charged little by little every time the brake pedal is pressed. Hybrid cars with serial drive are suitable for stop-and-go traffic.
Parallel drive
When a hybrid car has a parallel drive, the wheels are powered by both the electric motor and the gasoline engine. The batteries in a parallel drive are smaller than in a series drive.
Automakers design parallel drives to rely more on regenerative braking to charge the batteries. If the batteries need more power because regenerative braking is insufficient, the electric motor supplements the power needed to charge the batteries.
This is similar to how a generator works in a conventional vehicle. Hybrid parallel drives are advantageous on highways such as freeways. This is due to the incredible efficiency with which mechanical power is converted to electrical power.
Power-split powertrain
Some hybrids, such as the Toyota Prius, combine series and parallel powertrains into one powertrain called a power-split (series-parallel) powertrain. It essentially combines the advantages of each powertrain.
When driving around town, you get the benefits of a serial drivetrain. When driving on the highway, you get the benefits of a parallel drivetrain. This keeps the engine performing efficiently on most roads.
Of course, you can assume that split-power drives are expensive to buy and operate; they have large batteries and generators, and require a lot of computing power to run both drive systems.
If you don’t mind the extra cost, buy a hybrid that produces more power, consumes less fuel, and works well anywhere.