New energy vehicle classification and advantages and disadvantages analysis

When it comes to new energy vehicles, most people may only know pure electric vehicles, but in fact there are many types of new energy vehicles. In general, they mainly include plug-in hybrid vehicles, pure electric vehicles and fuel cell vehicles. Among these three categories, some of the major categories can be further subdivided into more types according to different forms.

New Energy Vehicle Classification Overview

What is a pure electric vehicle?

As the name suggests, a pure electric vehicle (BEV) is a car that is only powered by electricity. The power source of the vehicle is a rechargeable power battery. Compared with traditional internal combustion engine vehicles, pure electric vehicles have eliminated the internal combustion engine. Its working principle is shown in the figure.

Pure electric vehicle power schematic diagram

Since pure electric vehicles only need to be charged and do not burn oil, the vehicles themselves do not have problems such as pollution caused by exhaust emissions, and are therefore regarded as the trend of new energy vehicles.

What is a series hybrid vehicle?

The "series" in the name of a series hybrid electric vehicle (SHEV) can be simply understood as the engine and the electric motor are "connected" to drive the vehicle. It has a popular nickname - extended-range hybrid electric vehicle. Its working principle is shown in the figure.

Schematic diagram of the powertrain of a series hybrid electric vehicle

The biggest feature of this driving form is that the engine does not directly participate in the driving, but drives the generator to generate electricity when the battery power is low or the power is insufficient, and the electricity is input into the electric motor to drive the vehicle. The excess electricity is input into the battery pack for storage. The figure below shows the representative model of the series hybrid vehicle, the BMW i3.

Regarding series hybrid vehicles, an analogy can be made as follows: a man and a woman ride a single bicycle. The man (motor) is responsible for pedaling, and the woman (engine) sits on the back seat and cannot pedal. However, she can feed the man water when he is tired (inputting electrical energy into the motor), thereby driving the vehicle to continue moving forward.

What is a parallel hybrid vehicle?

A parallel hybrid electric vehicle (PHEV) is a vehicle in which the engine and electric drive system can drive the vehicle separately. The word "parallel" in the name can be simply understood as the engine and the electric motor are "parallel" and can drive the vehicle separately. The working principle is shown in the figure.

Parallel hybrid electric vehicle power diagram

The biggest feature of this driving form is that the engine and the electric motor have a power distribution mechanism to complete the power coupling. To put it simply, a parallel hybrid vehicle is a pure electric vehicle powertrain consisting of a battery pack + electric motor added to the powertrain of a traditional fuel vehicle consisting of an engine + transmission, and the two together drive the vehicle. The figure below shows the representative model of a parallel hybrid vehicle, the Mercedes-Benz C350 plug-in version.

Regarding parallel hybrid vehicles, an analogy can be made as follows: a man and a woman ride a tandem bicycle, the man (motor) is responsible for pressing the front pedal, and the woman (engine) is responsible for pressing the rear pedal, and the two work together to drive the bicycle forward; in this process, both the man and the woman can exert their own strength, or they can choose to rest according to actual needs.

What is a series-parallel hybrid electric vehicle?

Series-Parallel Hybrid Electric Vehicle (PSHEV) is based on the parallel hybrid drive form, adding an energy transmission path from the engine's power output: in addition to driving the wheels, the engine can also transfer energy to the battery pack through the generator. Its working principle is shown in the figure below.

Schematic diagram of the powertrain of a series-parallel hybrid electric vehicle

The word "hybrid" in the series-parallel hybrid vehicle can be understood as a mixture of series and parallel drive modes, or it can be equivalent to adding a direct drive system to the series hybrid solution, so that the engine can directly drive the vehicle under certain working conditions. The figure shows the representative model of the series-parallel hybrid vehicle, the BYD Song Plus DM-i.

Regarding parallel-parallel hybrid vehicles, an analogy can be made as follows: a man and a woman ride a tandem bicycle, the man (motor) is responsible for pressing the front pedal; the woman (engine) can press the rear pedal, or she can feed the man food when he is tired (input electrical energy into the motor) to give him strength to continue riding, and the two work together to drive the bicycle forward in different ways at different stages.

What is a fuel cell vehicle?

Fuel Cell Electric Vehicle (FCEV) usually uses hydrogen, methanol and other fuels to generate electricity through chemical reactions to drive the motor to work. The mechanical energy generated by the motor is transmitted to the drive wheels through the speed transmission device, thereby driving the vehicle. Its working principle is shown in the figure.

Fuel cell vehicle power schematic

The final emission of hydrogen fuel cell vehicles is only water, and they can also purify the air during their driving, bringing new possibilities for solving environmental problems. The following figure shows the representative model of hydrogen fuel cell vehicles, Hyundai NEXO, and the following figure shows the power system composition of Hyundai NEXO.

Hyundai NEXO power system composition

Each type of new energy vehicle has its own advantages and disadvantages.

Analysis of the advantages and disadvantages of different new energy vehicles

Relatively speaking, the structure of pure electric vehicles and fuel cell vehicles is simpler, the energy source is electricity or fuel, and the wheels are driven by electric motors through reducers. In contrast, the structure of plug-in hybrid vehicles is more complicated, both equipped with engines and electric motors, and the energy sources for driving the vehicle include fuel and electricity.

Overall, plug-in hybrid vehicles are a compromise solution, which has both the engine and fuel tank of a fuel vehicle and the battery, motor and electronic control system of a pure electric vehicle. In theory, plug-in hybrid vehicles combine the advantages of fuel vehicles and electric vehicles, which is the main reason why they are popular with consumers.

But a compromise is a compromise. While combining the advantages of fuel vehicles and electric vehicles, it also has the disadvantages of both types of vehicles, such as higher prices, short pure electric driving range, most of them are only equipped with slow charging, and higher maintenance costs.