4 types of electric vehicle charging systems

The electric vehicle charging system affects battery life and driving, and four different charging systems are based on function. Do you know why four types of electric vehicle charging systems are designed?

Electric vehicle charging system functions

The electric vehicle converts the energy stored in the power battery into mechanical energy through the motor to drive the car.

When the power battery power loss must be charged for the power battery to ensure sufficient power supply.

The charging system is a special device that converts mains electricity or other energy into DC high-voltage electricity to continuously provide electric energy for the power battery.

Electric vehicle charging

Electric vehicle charging system composition

The electric vehicle charging system consists of an electric vehicle charging jack, charging harness, vehicle charger, motor controller, power battery assembly and other high-voltage components and vehicle controller (VCU), battery management system (BMS, generally integrated into the battery pack), body control unit (BCM), low-voltage battery and so on.

Electric vehicle charging system composition

4 kinds of charging systems for electric vehicles

1. DC fast charge system

The charge conversion device of the DC fast charge is external, located on the charging pile. Therefore, the charging gun is sent to the car through the charging port of high voltage direct current, which can directly charge the power battery pack. It can be seen that the DC fast charge consumes electric energy.

Through the connection of the DC charging interface and the DC fast charging pile, after the communication between the vehicle controller and the battery management system to confirm that the DC charging conditions are met, the high-voltage direct current between the charging pile and the power battery is connected to charge the power battery.

Composition: DC charging interface (with high voltage wiring harness), power battery assembly.

Principle: When the DC charging device interface is connected to the vehicle’s DC charging port, the DC charging device sends a charging wake-up signal to the power battery management system BMS. According to the rechargeable power of the power battery, the BMS sends charging current instructions to the DC charging device. At the same time, the high-voltage positive relay and high-voltage negative relay of the BMS suction system are directly connected to the positive and negative terminals of the charging equipment and the power battery, and the power battery is charged.

DC fast charge system

2. AC slow charge system

AC slow charge when the AC to DC components are located in the car, that is the car charger. Therefore, the charging gun is sent to the car with alternating current, which needs to be converted into direct current through the car’s onboard charger to charge the power battery pack. It can be seen that AC slow charge consumes electric energy.

Through the AC charging interface, the mains power is introduced into the vehicle charger, the vehicle charger converts the AC into high voltage direct current, communicates with the vehicle controller and battery management system to confirm that the charging conditions are met, and connects the high voltage direct current between the vehicle charger and the power battery to charge the power battery.

Composition: AC charging interface, AC charging socket, plug, power battery, car charger

Principle: When the vehicle is in AC charging mode, the vehicle charger detects the CC and CP signals (charging gun insert, guide communication number) of the AC charging interface and wakes up the battery management system BMS, BMS wakes up the vehicle charger (OBC) and sends instructions to charge, while closing the main relay, and the power battery starts to charge.

AC slow charge system

3. Low voltage charging (DCDC)

DCDC charging converts high-voltage direct current into low-voltage direct current through the DCDC converter and charges the small battery of the low-voltage system, which consumes the high-voltage electric energy of the power battery pack.

Different from traditional fuel vehicles, electric vehicles have no generators, and the electric energy of low-voltage electrical devices (control systems, body appliances, comfort systems, etc.) on the car is provided by low-voltage batteries. When the vehicle controller (VCU) detects that the low-voltage battery is insufficient, it automatically wakes up the DC/DC device and converts the high-voltage DC of the power battery to 14V low-voltage DC to charge the low-voltage battery.

Composition: 12V lead-acid battery, motor controller, distribution box, power battery.

Principle: Before the power battery is powered on at high voltage, the low-voltage circuit system relies on the 12V lead-acid battery for power supply. When the high voltage is powered on, the motor controller converts the high voltage direct current of the power battery into low voltage direct current to charge the 12V lead-acid battery.

4. Brake energy feedback charging system

Energy recovery also involves AC to DC, but its DC conversion is completed by the motor controller, which is the wheel drag to drive the motor to generate AC power, and then the motor controller for rectification into high voltage direct current, to charge the power battery pack. Therefore, it does not consume energy but converts the braking energy into electricity.

Brake energy feedback charging system

When the electric vehicle braking or downhill, the drive motor will convert the kinetic energy of the car into electrical energy, and then through the motor controller, the car charger will convert the three-phase AC electricity into high voltage direct current to charge the power battery.

Composition: brake switch, power battery, drive motor, vehicle controller, high voltage wiring harness, etc.

Principle: The function of the energy recovery system is to change the driving motor from the driving state to the power generation state during the process of taxi or braking of the vehicle, and convert the kinetic energy of the vehicle into electric energy stored in the power battery.

Summary

Electric vehicles have four kinds of charging systems: AC slow charge, DC fast charge, energy recovery, and DCDC charging.

Three of them are energy-intensive: AC slow charge, DC fast charge, and DCDC charging are all energy consumption, and 1 is not energy consumption: energy recovery.

Ac slow charge and DC fast charge are used to charge the power battery pack in a specific way. The main difference between AC slow charge and DC fast charge is the location of the AC to DC components.

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