1. Toll system function
Charging system is the energy supply system of new energy vehicles (including pure electric vehicles and plug-in hybrid vehicles), which provides power energy to ensure the continuous running of vehicles.
New energy vehicle charging equipment should have the following functions:
(1) Convert the commercial power into electric vehicle to charge and supply the power corresponding to the rated working condition of the power battery.
(2) Control the start and stop of charging according to the real-time state of the power battery, and automatically stop charging when the power battery is full.
(3) According to the electric quantity and temperature of the power battery, control the adjustment of the charging current and the heating of the battery.
(4) The charging mode can be selected according to the demand for charging time, that is, fast charging mode or slow charging mode.
2. Type of charging system
According to the position of charging equipment, the charging system of pure electric vehicle has two types: on-board and off-board
(1) car charging. On-board charging refers to charging the power battery by using the ground AC power grid and the on-board charger (also called the on-board charger). Car chargers are generally designed with low charging rate and long charging time (5 ~ 8h). Both the charger and the battery management system (responsible for monitoring the voltage, temperature and charging state of the power battery) are installed in the vehicle, so they can easily communicate with each other by using the internal circuit network of the electric vehicle.
(2) Off-board charging. Off-vehicle charging, that is, ground charging, refers to charging the power battery pack at a charging station in a special or public place by using a special or general charger. Usually, the power, volume and mass of off-board chargers are relatively large, so as to be able to adapt to various charging methods. Off-board charger and power battery management system are physically separated. According to the charging time, there are two charging methods for pure electric vehicles: fast charging and slow charging. Fast charging is suitable for charging at the charging station, with large current, and slow charging is suitable for 220V household charging. Although the technical parameters of different manufacturers are different, the charging current is generally between 10 and 15A.
3. Charging method
There are two charging methods for pure electric vehicles: contact and induction.
(1) contact type. Contact type is also called coupling type or conduction type. In the contact charging method, the AC power cable with plug is directly inserted into the socket of electric vehicle to charge the battery. Its advantages are simplicity and high efficiency; The main disadvantages are low charging current and long charging time.
(2) induction. With the rapid development of power electronics technology and converter control technology, as well as the maturity and popularization of high-precision controllable converter technology, the contact charging technology of electric vehicles adopts a constant voltage and current-limiting charging method with continuous changes of charging current and charging voltage. The biggest problem of contact charging is safety and universality. In order to meet the strict safety charging standards, many measures must be taken in the circuit to make the charging equipment charge safely in various environments. The new technology of induction charging for electric vehicles has developed rapidly. The induction charger uses the transformer principle of high-frequency AC magnetic field to induce electric energy from the primary side of the vehicle to the secondary side of the vehicle to achieve the purpose of charging the battery. The biggest advantage of induction charging is safety, because there is no direct contact between the charger and the vehicle, even in bad weather, such as rain and snow, there is no danger of electric shock when charging the vehicle.
The induction charging method is shown in the following figure, and the battery is charged by converting energy through electromagnetic induction coupling. Its characteristics are: easy to use, and there is no danger of electric shock when charging in bad weather. The charger converts 50 ~ 60 Hz ordinary electricity into 80 ~ 300 Hz high-frequency electricity, and then induces high-frequency alternating current to the electric vehicle, which greatly shortens the charging time.
4. Charging pile
(1) Function of charging pile
The charging current of electric vehicles is relatively large (that is, the power is very high). If civil 220V plug is used, the charging cable and plug can't bear such a large current, and the plug and wire will be burnt out, so special charging pile is needed to bear such a large current.
The charging pile is a charging station for electric vehicles, which looks like a parking stopwatch. A charging pile can charge two or more cars at the same time, and the time from battery dead to full charge is 6 ~ 8h. Charging piles can be charged in three ways: counting time, counting electricity or counting electricity. It can also be used as a terminal for citizens to buy electricity. In order to improve the efficiency and practicability of public charging piles, the multi-charge and multi-charge function of electric bicycles will be added in the future.
(2) Development of charging piles
Affected by the rapid development of new energy vehicles, supporting facilities such as charging piles and charging stations have also ushered in rapid development. From 20 10 to 20 13, the number of charging stations in China has rapidly increased from 76 to 5 18, with a compound annual growth rate of 89.6%, and the number of charging piles has also increased from 1 122 to 22,528, with a compound annual growth rate of/kloc. The construction of charging facilities is one of the key links in the demonstration and promotion of new energy vehicles. Thanks to the rapid growth of the application of new energy vehicles, the charging facilities industry of new energy vehicles in China will face huge development space. Previously, due to the small scale of electric vehicles, the investment in the construction of charging facilities was huge, the short-term benefits of investment were not obvious, and the construction speed of charging facilities was slow.
With the country's increasing support for new energy vehicles, a wave of charging pile infrastructure construction has been set off all over the country. Up to now, Beijing, Shanghai, Shenzhen, Tianjin, Chongqing, Hangzhou, Hefei and Wuhan have put forward construction plans for charging piles.
(3) charging technical requirements and safety requirements of charging piles
The charging pile is an electric vehicle charging station. Charging piles are usually fixed on the roadside or in parking lots, which provide AC power for electric vehicles with on-board chargers by using special charging interfaces and conduction modes, and have corresponding communication, charging and safety protection functions. Charge electric vehicles by putting in coins or buying special ic cards.
Charging piles can be divided into AC charging piles and DC charging piles. The AC charging pile is a power supply device installed outside the electric vehicle and connected to the AC power grid, which provides AC power for the on-board charger of the electric vehicle, and also has the function of metering and charging. DC charging pile is a power supply device which is fixedly installed outside the electric vehicle and connected with the AC power grid to provide low-power DC power for the power battery of the electric vehicle. DC charging pile has the function of charger, which can monitor and control the state of rechargeable battery in real time, and at the same time, DC charging pile can measure the charging amount.
Safety requirements for charging piles:
(1) The substation shall be provided with safety fences, warning signs, safety signal lights and alarm bells.
② Warning signs of "Stop, High Voltage Danger" should be hung on the safety fence of high voltage distribution room and transformer room or substation. Warning signs must face the outside of the fence.
(3) The high-voltage power distribution device shall have obvious operating instructions. The grounding point of the equipment should be clearly marked.
④ There should be obvious signs of "safe passage" or "safe exit" indoors.
In addition, the layout design of substation and distribution equipment should be convenient for installation, operation, handling, maintenance, testing and monitoring.