best value public electric car charging stations engineering technology

The main functions of the remote monitoring electric vehicle charging pile scheme are:

(1) Real-time information sharing between operating units, electric vehicle users and payment platforms is realized to facilitate the charging of electric vehicles at any time.
(2) Help electric vehicles truly achieve “24-hour” charging services, and upload information such as charging and payment fees to the background of the operating charging pile enterprise in real time.
(3) Connect charging piles with electric vehicle users, operating units, mobile companies, UnionPay and even the State Grid to achieve a large amount of data interaction.
(4) Centralized management of distributed charging pile terminals, real-time grasp of terminal operating conditions, reduction of operating costs of charging pile enterprises, and improvement of service quality and operating efficiency of operators.

(5) Reliable operational data reports provide decision-making basis for operators, improve the informatization level of the charging industry, and promote the development of the electric vehicle charging industry and the construction of intelligent cities.
(6) Video surveillance and image capture of the site, view the snapshot pictures of each operation point, collect and store video evidence of the process of man-made damage to the charging pile, and ensure the safe tracking of the charging pile equipment for evidence collection at any time.

(7) 2G/3G/4G wireless devices use wireless networking, which is not troubled by wiring problems, and is less affected by on-site environmental factors. Where there is a mobile phone signal, the network can be connected normally, and the installation is simple and flexible; 3G/4G wireless routers pass Simple page configuration, automatic dial-up networking and active sending of connection requests, quick access to the router management platform; WEB architecture design, easy access.

Scheme 1: Charging pile terminal solution based on wireless data transmission RTU technology This scheme mainly consists of AC/DC charging pile, wireless data transmission terminal RTU, various 2G/3G/4G wireless networks and communication networks, charging pile system management platform software composition, as shown in Figure 1.

The wireless data transmission RTU can provide various interfaces of RS-232/RS-485/Ethernet/USB to connect with the charging pile and corresponding supporting equipment; the wireless data transmission RTU transmits the data of various charging pile terminals wirelessly through various wireless networks Transparent transmission to the server-side charging system management platform, the system platform software includes metering and billing system, charging monitoring system, power distribution monitoring system, security monitoring system, etc.

Scheme 2: Application scheme of industrial-grade wireless router charging pile data transmission system The charging pile wireless data transmission application scheme consists of four parts: electric vehicle, charging pile, router and third-party M2M cloud management platform. Among them, the M2M cloud management platform is composed of a WEB terminal control platform, a mobile APP terminal, and a cloud server. People can query the detailed geographical location of the charging pile through the WEB terminal or APP client at any time, and use a 3G/4G router to provide the charging pile. The wireless data transmission application solution establishes a high-speed and stable networking and data transmission channel, and transmits all charging, payment and other information to the enterprise background for the operating enterprise to conduct business analysis and operation. At the same time, through the third-party M2M cloud management platform, the operating enterprise realizes the unified operation status supervision of the charging pile terminals scattered in different locations, effectively reducing the operation and maintenance cost of the enterprise. The topology diagram of charging pile wireless data application (Caimao 2G/3G/4G router) is shown in Figure 2. The concentrator and battery management system realize reliable wireless data remote transmission. According to the wirelessly transmitted data, the charging management service platform can realize powerful operator management, user management, customer service management, charging station (pile) management, data statistical analysis, Alarm failure, repair report management, equipment map display functions. Reliable wireless data connection and combination save the cost of installation cost, so that the majority of users can use the mobile phone APP (main functions include user center, device management, device control/view, charging plan, device authorization sharing, device release and rental, online pile search and Navigation, online settlement and payment, etc.) under the friendly and intuitive screen, better experience the convenience of electric vehicle charging.

(1) Platform layer
The platform layer uses data mining technology, cloud computing technology, and portal technology for electric vehicle charging services to provide basic services such as user management, identity authentication, authority control, charging device information recording, and mass data storage for electric vehicle charging, and supports mobile APP implementation. Charging device usage inquiry, positioning and navigation, charging reservation and charging device locking and other services, and data exchange with related external systems to achieve cross-application and cross-system information exchange, sharing and collaboration, and can push charging for users through in-depth mining Value-added services such as service plans, charging stores, etc.

(2) Network layer
The network layer is the link between the platform layer and the terminal layer, providing a transmission channel for various data such as various user information and electric vehicle charging information. The network layer includes both high-speed wireless networks in the form of Wi-Fi and the wide-area Internet.

(3) Terminal layer
The terminal layer includes electric vehicle charging terminal facilities (AC piles, DC piles, etc.), and user equipment such as smartphones and tablet computers. The electric vehicle charging terminal can send the charging information of the vehicle to the remote platform through the network layer, and can also receive the control commands issued by the platform. Terminal devices such as smartphones and tablet computers interact in real time through the APP application software on them, receive user input, and display various services provided by the system.

The system communication architecture diagram is shown in Figure 3. The charging terminal contains a Wi-Fi communication module, which can communicate with the Wi-Fi router: the Wi-Fi router sends information to the cloud platform server through 2G, 3G or optical fiber networks, etc.; GPRS and CDMA etc. communicate with the background server. In addition, in order to ensure information security, a key management system and encryption machine are deployed in the cloud platform, and an embedded security module chip (ESAM) is added to the charging device.

2. System composition and function

The cloud platform electric vehicle intelligent charging system is mainly composed of cloud platform, intelligent charging device and intelligent terminal APP application software.

1) Electric vehicle charging service cloud platform
The electric vehicle charging service cloud platform is a comprehensive platform that provides data release, collection, storage, processing, maintenance and mining for electric vehicle charging. In order to meet the needs of business development, the electric vehicle charging service cloud platform supports a variety of industries with millions of users.

(1) Functional support subsystem based on cloud computing technology
This subsystem deeply studies the characteristics of electric vehicle charging services, uses cloud computing technology to develop a unified management subsystem for virtual machine and physical machine resources, and comprehensively and flexibly manages and controls all computing resources to provide the entire electric vehicle intelligent charging system. Flexible computing power. According to the characteristics of electric vehicle charging service access, load balancing technology is adopted to support high concurrent access of a large number of users. Provide user management, identity authentication, authority control, charging device information recording, electric vehicle charging massive data storage and processing and other functions, support mobile APP to realize charging device usage query, positioning navigation, charging reservation, charging device locking and other business applications .

(2) Data exchange subsystem
In order to solve the problems of various data exchange and integration in the system, the data exchange subsystem is mainly designed from the following four aspects.
①Effectively reduce the degree of coupling between systems, so that each application system is only logically related to the data exchange subsystem, without considering the specific deployment of the other end of the data exchange, so that a simple data fusion is formed between systems.

②Improve the standardization of the data exchange interface, so that the system interface faces the data exchange subsystem in a unified way, and has consistency in the logic and technical form of the interface, which provides a foundation for the stability and specification of the system interface.

③ Improve the openness of data exchange, so that the data exchange subsystem is like a logical data bus between systems, which can provide flexible and various forms of interfaces to the outside world.
④ Ensure the efficiency and stability of data exchange, and effectively ensure the efficiency and stability of the data exchange process from the system design level.

(3) Data mining subsystem
In-depth analysis of various services provided by the entire electric vehicle intelligent charging system, according to different categories, characteristics and actual needs of services, using data extraction, storage, management and display technologies to develop business applications such as electric vehicle charging data analysis and user behavior mining , to provide users with in-depth and efficient value-added services. The data mining subsystem will mainly complete the following two typical tasks.

①By collecting and analyzing the charging time data of a large number of users, the charging density of users in different time periods can be mined, and the influence rules of users’ charging behavior on the grid load can be calculated, which can provide strong support for load prediction and provide a basis for power dispatching.
②By analyzing the data of massive user charging locations, the distribution of charging demands of users in different regions and different locations can be excavated, and the utilization of currently built charging facilities in various locations can be calculated, providing direct guidance for further construction of charging facilities.

2) Smart charging device
The principle block diagram of the intelligent charging device is shown in Figure 4, including MCU unit, digital energy meter, Wi-Fi communication module, FLASH storage unit, protection unit, power conversion module, contactor, emergency stop switch, etc. Among them, the MCU unit is the control core of the charging device, which completes the command control and information distribution. It adopts the low-power and cost-effective CORTEX-MO series chips, communicates with the Wi-Fi communication module through the serial port or SPI bus, and communicates with the digital communication module through the 485 bus. The electric energy meter communicates with the FLASH storage unit through the 1C bus, and the MCU is connected with the contactor through the drive circuit to realize the on-off control of the charging electric energy output. The Wi-Fi communication module adopts a low-power Wi-Fi module to realize data communication with the wireless gateway, thereby realizing remote control of the switching state of the charging device, and reporting of current, power, and energy information. The power conversion module is used to convert alternating current into direct current, provide direct current of different voltage levels, and provide power for other circuits in the charging device.

In addition to the traditional functions of charging, metering, and protection, the intelligent charging device will be more adaptable to the ever-changing technological changes while improving the intelligence of the system.
(1) Handheld terminal control function. The distributed charging device can be controlled to start and stop through the mobile terminal APP. When the charging device meets the charging conditions, the user can control the start and stop of the charging device in real time through mobile terminals such as mobile phones.

(2) Charging information upload function. The distributed charging device can upload the charging information to the server and display the charging information in real time through the APP interface installed on the mobile phone, including the current charging voltage, charging current, charging capacity, charging rate, billing information, fault information, working status information, etc.

3) APP client station

With the popularity of smart phones, APP client software has been applied to all aspects of daily life. This system has designed two versions of client software, which respectively support i0SV7.0.0 and above and Android V2.3.3 and above. The overall design is C/s architecture, and the client is a multi-layer architecture. Provide better flexibility and powerful scalability. The multi-layer system is a 3-layer structure for the client, which is allocated from the view layer, the business logic layer, and the business entity layer.

(1) The view layer is the interface that interacts with the user. In response to the user’s request, the interface of the business logic layer is called for logical processing, and is displayed to the user in different forms according to the results. The view layer includes map display, payment settlement, status display, control interface and query interface.
(2) The business logic layer completes the actual business logic, including the data request to the server and the reading of the local database.

(3) The business entity layer includes various business entities, data request and data analysis to the gateway server, data request and data analysis to the platform server, and database maintenance.
The APP client software calls the corresponding modules of the business logic layer according to the functions selected by the user. The business logic layer is responsible for the organization of business processes, and calls the modules of the business entity layer to communicate with the gateway server (or platform) through the gateway server interface (or platform server interface). server) for information exchange. The APP client software has the following functions:

(1) Map function. The intelligent charging device has the function of map application, which can query the location information of the charging device through the map and navigation.
(2) Status display function. Display various states of the smart charging device through the mobile APP.
(3) Payment function. The system has the function of charging and settlement. By binding accounts with Alipay, WeChat accounts, etc., it can realize intelligent charging in fixed, quantitative, timing and other ways.
(4) Control function. The settings and control of the intelligent charging device are realized through control commands, including starting charging, canceling reservations, and stopping charging.
(5) Query function. Users can query the details of charging data (number of times, accumulated).

Read more: Electric Vehicle Charging Station – GPRS Wireless Access Solution