Suffering from decision paralysis, you've decided to experience the increasingly popular hybrid vehicle but don't know where to start? After a barrage of sales pitches from the dealership, you still don't understand the differences between plug-in and non-plug-in hybrids, or the distinctions between series, parallel, and series-parallel hybrids. No worries, keep reading and you might understand!
Perspective view of a hybrid vehicle
Traditional cars use an internal combustion engine to burn gasoline to generate power and drive the vehicle. Hybrid vehicles (HEVs) have an additional electric drive system compared to traditional gasoline-powered cars, combining both "oil" and "electric" power sources. However, the specifics of how they are combined are quite complex.
Traditional automotive powertrain flowchart
Hand in hand
By adding an electric drive system (including a generator, electric motor, and battery) in series to the structure of a traditional car, a series hybrid electric vehicle (also known as a range-extended electric vehicle) is created. As the name suggests, this is an electric-powered car that uses its own electricity. Of course, the electricity is not generated out of thin air; it is produced by the internal combustion engine burning gasoline to generate kinetic energy, which powers the generator to produce electricity, which is then supplied to the electric motor to drive the car. Excess electricity is temporarily stored in the battery.
At this point, you might wonder, why not just use gasoline directly instead of going through all this trouble? It's well known that the conversion from chemical energy to electrical energy to kinetic energy wastes significantly more energy than the conversion from chemical energy to kinetic energy. Furthermore, adding an electric drive module seems to increase the vehicle's weight and fuel consumption, which appears to be less energy-efficient and environmentally friendly. However, because the engine doesn't directly drive the car but only powers the generator, its structure is very simple (e.g., it eliminates the need for a gearbox). The battery's output power is more stable than the generator's, generating almost no excess energy consumption. Therefore, in the long run, it still achieves the goal of energy conservation.
Series hybrid electric vehicle powertrain flowchart
each doing their own thing
Just as there are series connections, there are also parallel connections. In a parallel hybrid electric vehicle, the electric drive system is an independent entity. The internal combustion engine and electric motor are structurally independent, providing power to the vehicle individually or together. However, their independence does not mean they are completely separate. For example, during energy-intensive situations such as acceleration and hill climbing, both engines often drive the vehicle together; during constant speed and normal driving, only the internal combustion engine operates; during starting and low-speed coasting, only the electric motor is needed to meet energy consumption; of course, during deceleration and braking, or when the battery power is insufficient, the excess power provided by the internal combustion engine is converted into electrical energy and stored in the battery. The initial intention of the parallel design is to recover excess kinetic energy, saving energy and electricity.
Flowchart of parallel vehicle powertrain system during acceleration and hill climbing
In addition to being classified according to different power system structures, hybrid vehicles are also divided into plug-in and non-plug-in types (i.e. whether or not they require external charging).
Plug-in hybrid electric vehicles (PHEVs), simply put, are essentially "wet-and-ready" pure electric vehicles. PHEVs consume electricity during normal driving, but when the battery is low, their true nature is revealed, forcing them to activate the internal combustion engine to continue driving the car. At this point, the hybrid vehicle is no different from a traditional car. The internal combustion engine in a PHEV only provides power to the vehicle and does not charge the battery. The battery needs to be connected to an external charging station to be fully charged, whereas non-plug-in hybrids do not require charging and are self-sufficient in electricity. Compared to non-plug-in hybrids, PHEVs typically have larger battery capacities. Once battery technology bottlenecks are overcome and battery capacity is large enough, pure electric vehicles will emerge!
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