Classification of new energy vehicles and electric cars

Ⅰ. New energy vehicles

The future development trend of automobile industry technology is low-carbon, as shown in Figure 1. In addition to power technology, transmission technology and manufacturing technology, new energy technology is also one of the key technologies to realize the low-carbonization of automobiles. It plays an indispensable role in the development of low-carbon automobiles.

Classification of new energy vehicles and electric cars
Figure 1 Future development trend of automobile industry technology

New energy vehicles generally refer to vehicles that use new power systems and rely entirely or mainly on new energy sources, including plug-in hybrid (including extended range) vehicles, full electric cars, and fuel cell vehicles.

ⅰ.Electric cars

An electric vehicle refers to a vehicle that uses electric energy to drive a motor as a power system in whole or in part. Electric vehicles include full electric cars, hybrid vehicles and fuel cell vehicles

(1) full electric cars

A pure electric vehicle (BEV) is a vehicle that is powered by an on-board power supply and drives the wheels with a motor, which meets the requirements of road traffic safety regulations.

2) Hybrid vehicles

Hybrid vehicles refer to vehicles that can obtain power from at least the following two types of energy stored on-board; one is consumable fuel; the other is rechargeable energy/energy storage devices.

In 2003, the United Nations defined a hybrid vehicle: in order to promote vehicle innovation, a vehicle that has at least two energy converters and two energy storage systems (on-board state).

The International Electrotechnical Commission defines a hybrid electric vehicle as: a hybrid electric vehicle that has more than one energy converter to provide driving force, that is, an electric vehicle that uses a battery and a secondary energy unit. The secondary energy unit refers to the prime mover or generator set that uses a certain fuel as the energy source. Fuels mainly include diesel, gasoline, liquefied petroleum gas, natural gas and alcohol. The prime movers are mainly internal combustion engines and other heat engines.

Based on the above description of the definition of hybrid electric vehicles, referring to the relevant documents of the International Energy Agency (IEA), it is generally believed in the industry that vehicles with the following characteristics of energy and power transmission routes are called hybrid vehicles.

① The energy transmitted to the wheels to propel the vehicle movement is collected from at least two different energy conversion devices (such as internal combustion engines, gas turbines, Stirling engines, electric motors, hydraulic motors, fuel cells, etc.).

② The energy conversion device must absorb energy from at least two different energy storage devices (such as fuel tanks, batteries, flywheels, super capacitors, high-pressure hydrogen storage tanks, etc.).

③At least one of the channels flowing from the energy storage device to the wheel is reversible (both releasing energy and absorbing energy), and at least one other is irreversible.

④ The reversible energy storage device supplies electric energy. The irreversible power component of a hybrid electric vehicle is the engine, and the energy storage component is the fuel tank; the reversible power component is the motor, and the corresponding energy storage component is the power battery, super capacitor, fuel cell, etc.

At present, diesel hybrid models are developing rapidly in the international market.

(3) Fuel cell vehicles

A fuel cell vehicle is a vehicle that uses a fuel cell as a power source.

ⅱ. Gas fuel vehicles

Gas fuel vehicles are vehicles that use gas fuel.

There are many types of alternative gas fuels for automobiles, and the common ones are natural gas and liquefied petroleum gas. Special gas-fuel vehicles are vehicles that use gases such as liquefied petroleum gas, natural gas or coal gas as the engine fuel, including dual-fuel vehicles and dual-fuel vehicles.

(1) Dual-fuel vehicles

Dual-fuel vehicles refer to two relatively independent fuel supply systems (one for natural gas or liquefied petroleum gas, and the other for fuels other than natural gas or liquefied petroleum gas). The two fuel supply systems can be separate but not common. Automobiles that supply fuel to cylinders, such as gasoline/compressed natural gas dual-fuel vehicles.

(2) Dual-fuel vehicles

Dual-fuel vehicles refer to two fuel supply systems (one for natural gas or liquefied petroleum gas, and the other for fuel other than natural gas or liquefied petroleum gas). The two fuel supply systems supply fuel to the cylinders in a predetermined ratio. , Cars with mixed combustion in the cylinder, such as diesel/liquefied petroleum gas dual-fuel cars, etc.

ⅲ. Biofuel vehicles

Biofuel vehicles refer to vehicles that use biofuels or fuel fuel blended with biofuels, including ethanol-fueled vehicles and biodiesel vehicles.

ⅳ. Hydrogen fuel vehicle

Hydrogen fuel vehicles are vehicles that use hydrogen as the engine fuel.

General internal combustion engines are usually injected with diesel or gasoline, while hydrogen fuel vehicles use gaseous hydrogen instead. There are three applications of hydrogen internal combustion engines in automobiles: pure hydrogen internal combustion engines, hydrogen/gasoline dual-fuel internal combustion engines, and hydrogen/gasoline mixed-fuel internal combustion engines.

Ⅱ, the classification of full electric cars

ⅰ. Classified according to the composition and layout of the drive system

According to the composition and layout of the drive system, full electric cars are divided into four types: mechanical transmission type, transmissionless type, differentialless type and electric wheel type, as shown in Figure 2.

Classification of new energy vehicles and electric cars
Figure 2 Layout form of pure electric vehicle drive system C-clutch D-differential FG a fixed speed ratio reducer GB-transmission M-Motor

(1) Mechanical transmission type

The structure of a mechanical transmission pure electric vehicle is shown in Figure 2(a). It is developed based on the structure of front and rear-wheel drive of the engine of a fuel vehicle. It retains the transmission system of a fuel vehicle. The difference is Replace the internal combustion engine with an electric motor. This structure can ensure the starting torque of the pure electric vehicle and the backup power at low speed, and it has low requirements on the drive motor. Therefore, a motor with a smaller power can be selected.

(2) No transmission type

A structure of a transmissionless pure electric vehicle is shown in Figure 2(b). The biggest feature of this structure is the elimination of the clutch and transmission, the use of a fixed-speed ratio reducer, and the variable speed function by controlling the motor. The advantage of this structure is that the mechanical transmission device is light in weight and small in size, but it has higher requirements on the motor. It not only requires a higher starting torque, but also requires a larger reserve power to ensure the start of a pure electric vehicle. , Climbing and acceleration and other dynamic performance.

Another structure of a transmissionless pure electric vehicle is shown in Figure 2(c). This structure is similar to the layout of the traditional fuel vehicle’s front-side engine and front-wheel drive. It integrates a motor, a fixed speed ratio reducer and a differential into a whole, and two half shafts are connected to drive the wheels. This structure is very common in small electric vehicles.

(3) Type without differential

The structure of a pure electric vehicle without differential is shown in Figure 2(d). This structure uses two motors, and the two wheels are driven separately through a fixed speed ratio reducer, which can realize independent adjustment of the speed of each motor. Therefore, when the car is turning, the differential speed of the two wheels can be controlled by the electronic control system of the motor, so as to meet the steering requirements. However, the motor control system of this structure is relatively complicated.

(4) Electric wheel type

A structure of an electric wheel-type pure electric vehicle is shown in Figure 2(e). This structure is to install the motor directly inside the driving wheel, which can further shorten the power transmission path between the motor and the driving wheel, and reduce the loss of energy on the transmission path. However, in order for a pure electric vehicle to achieve normal work, it is necessary to add a planetary gear reducer with a relatively large speed to reduce the rotation speed of the motor to the ideal rotation speed to drive the wheels.

Another structure of an electric-wheel-type pure electric vehicle is shown in Figure 2(f). This structure installs the outer rotor of the low-speed outer rotor motor directly on the rim of the wheel, removing the reduction gear, so there is no mechanical transmission between the motor and the driving wheel, no mechanical transmission loss, high energy transmission efficiency, and space The utilization rate is relatively large. However, this structure has higher requirements for the performance of the motor, which requires a high starting torque and a large backup power to ensure the reliable operation of the vehicle.

ⅱ. Different classifications of the number of connected car power supplies

According to the number of on-board power sources, full electric cars can be divided into single-power full electric cars and multi-power full electric cars.

(1) Single power supply pure electric vehicle

The main power source of single-power full electric cars is generally storage batteries, such as lead-acid storage oil, nickel-hydrogen batteries and lithium-ion batteries. The structure of a single-power pure electric vehicle is relatively simple, and the control is relatively simple. Its main disadvantage is that the instantaneous output power of the main power source is easily affected by the performance of the battery, and the feedback efficiency of the vehicle braking energy is also subject to the maximum acceptable current and The state of charge (remaining power) of the battery.

(2) Multi-power electric vehicles

Multi-power full electric cars are generally composed of batteries and energy storage devices. The use of battery plus super capacitor or battery plus flywheel battery power supply combination can reduce the requirements on the capacity, specific energy, and specific power of the battery. When the car starts, accelerates, and climbs, the auxiliary energy storage device (super capacitor, flywheel battery) can output high power in a short time, assist the battery to supply power, and improve the power performance of the electric car; when the car is braking, use the auxiliary The energy storage device accepts high current charging to improve the efficiency of braking energy feedback.

Ⅲ. Change the use of different classifications

According to different uses, full electric cars are mainly divided into three types: pure electric cars, pure electric trucks and pure electric buses.

(1) Pure electric car

Pure electric cars are currently the more common full electric cars. Except for some concept cars, pure electric cars have been mass-produced and have entered the market.

(2) Pure electric truck

Pure electric trucks are full electric cars mainly used to transport goods. Pure electric trucks used for road transportation are still relatively rare. In mines, construction sites and some special sites, some pure electric trucks with large tonnage have already appeared.

(3) Pure electric bus

A pure electric bus is a pure electric vehicle with the purpose of carrying passengers. At present, pure electric small buses are relatively rare; pure electric buses are mostly used as buses.

In addition to the above three types, there is also a pure electric vehicle called pure electric mini-car. Pure electric mini-cars have passenger, cargo, and other purposes. As shown in Figure 3, the characteristics of these pure electric mini-cars It is small in size, low in speed (generally the maximum speed is 50~60km/h), the mileage is short, and the cost is low.

Classification of new energy vehicles and electric cars
Figure 3 Example of a pure electric mini car