Knowledge Popularization: classification of pure electric vehicles and composition of electric drive control system

According to the layout classification of the driving structure, the basic structure of pure electric vehicle is mainly divided into four types, namely, the traditional driving mode and the motor drive axle combined driving mode, as well as the motor drive axle integrated driving mode and the hub motor decentralized driving mode.

Because when the car turns, the turning radius of the outer wheel is greater than that of the inner wheel, it is necessary to meet the requirements of different wheel speeds on both sides of the car through the differential. The traditional driving mode and the motor drive axle combined driving mode need to adopt the mechanical differential with planetary gear structure. The motor drive axle combined driving mode can adopt mechanical or electronic control. Hub motor decentralized drive mode can realize electronic differential control.

Pure electric vehicles are now mainly divided into electric buses and electric cars according to their uses. Because the energy of pure electric vehicles is general, they are suitable for specific vehicles with low performance requirements, such as sightseeing cars, golf course cars, electric bicycles and electric tricycles, as well as self driving by the disabled.

The structure of pure electric vehicle mainly covers electric drive control system, vehicle chassis, body and various auxiliary devices.

According to the working principle, the electric drive control system is divided into three parts: on-board power supply module, electric drive main module and auxiliary module.

The on-board power module covers battery power supply, energy management system and charging control gas.

First, battery power.

Battery is the only energy source of pure electric vehicle. In addition to the electric energy required for driving, it can also supply the working power supply of various auxiliary devices of the vehicle. Before the battery is installed on the vehicle, it is combined into the required voltage level through series and parallel connection. Multiple 12 V or 24 V batteries are connected in series into a 96 V to 384 V high-voltage DC battery pack, and different voltages are supplied through DC or DC converter.

Second, energy management system.

The key function of the energy management system is to allocate energy during vehicle driving, coordinate the energy management status of each functional part, and make the maximum use of energy. The energy management system and the central control unit of the main electric drive module jointly control the power generation feedback, so that the energy can be recovered when the electric vehicle decelerates, brakes and taxis downhill, so as to improve the endurance of the electric vehicle.

Third, charging controller.

The charging controller converts the power supply system of the power grid into the system required for battery charging, that is, it converts the AC into the DC of the corresponding voltage, and controls the charging current according to the requirements. The charger starts with a constant current charging period. When the battery voltage rises to a certain value, the charger starts the constant voltage charging period, and the output voltage remains at the corresponding value. When the charger starts the constant voltage charging period, the current decreases slowly. After the charging current decreases to a certain value, the charger starts the trickle charging period.

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