best value public electric car charging stations engineering technology

1.1.1 operation characteristics and mode of electric vehicle

1. Operation characteristics of electric vehicles

(1) It has more stored electric energy and large charging power. The stored electric energy of an ordinary electric vehicle is about 40kwh (KWH), which is equivalent to the electricity consumption of an ordinary household for half a month. In order to fully charge the battery of electric vehicles in a short time, the charging power of the charger is large. Generally, the charging power of the on-board charger (slow charging) is 2-3kw, the charging power of the special DC charging pile is 10~100kw, and it takes 1-2 hours to fully charge the on-board battery of ordinary electric vehicles with a 20kW DC charging pile.

The stored electric energy of the electric bus is 250-300kwh, the charging power of the on-board charger is 5-20kw, and the charging power of the special DC charging pile is 20-200kw. It takes 4-6 hours to fully charge the on-board battery of the electric bus with a 40kW DC charging pile. The shorter the charging time of the electric vehicle, the greater the output power requirement of the charging pile.

(2) The running distance is close. Generally, the maximum mileage of electric vehicles is about 300km. Considering road conditions, air conditioning, safety factor, battery attenuation and other factors, the actual one-way operation is 150-200km. If there is no support of charging station (pile), the activity radius shall not exceed 75-100km

2. Operation mode of electric vehicle

The service objects of electric vehicle charging station are all kinds of electric vehicles, and the charging station must meet the charging needs of different electric vehicles. Under different operation modes, electric vehicles have different requirements for driving range and charging time, which directly affects the construction mode and power demand of charging stations. According to the current city’s target market positioning of electric vehicles and the development trend of electric vehicles, there are the following operation modes according to the purpose of electric vehicles:

(1) Bus operation mode. The bus operation mode has certain commonalities, and usually the driving route, mileage and driving time are fixed. The bus operation mode should adopt the whole vehicle charging mode. This is because their driving mileage and path can be estimated, and they can make full use of the night shutdown period to charge to meet the next driving mileage needs. Since electric buses usually have special parking places, charging stations can be built in the parking places of the first and last bus stops, and the conventional charging can be carried out during the low hours at night. The driving range of electric buses for one-time charging should at least meet the one-way running mileage, and the rapid supplement of electric energy should be realized in case of emergency.

(2) Taxi operation mode. According to the driving range of a taxi after a charge, necessary charging facilities should be provided within its corresponding travel range. Taxis need to supplement electric energy in a timely and rapid manner to maximize the operation time and obtain greater economic benefits. Special charging stations or battery replacement points should be established in the urban area to improve the operation efficiency. During the operation period of the taxi, it should be able to complete the electric energy supplement through rapid charging or rapid replacement of the battery pack.

(3) Business vehicle or social vehicle operation mode. Vehicles in the operation mode of official vehicles or social vehicles are driven by the drivers of units and departments or the public. Corresponding charging facilities should be built in the areas where official vehicles are concentrated or residential areas. The driving routes and mileage of official vehicles, business vehicles, social vehicles, etc. can generally be estimated; The driving route and mileage of the engineering vehicle are not fixed and change greatly. It should be able to complete the electric energy supplement through rapid charging or rapid replacement of the battery pack.

(4) Operation mode of demonstration area. If the number of vehicles equipped for the demonstration operation is limited, in order to improve the vehicle operation efficiency, the way of replacing the battery pack should be adopted, but this requires increasing the investment of the battery pack. If the equipped vehicle can meet the operation requirements, the whole vehicle charging mode should be adopted, so as to reduce the investment of battery pack and the workload caused by battery replacement operation. In view of the small number of vehicles in the demonstration area and the relatively centralized operation range, a centralized large-scale charging station (battery replacement point) can be established in the demonstration area.

(5) Private car operation mode. The parking time and location of private cars used for commuting are relatively fixed, which can make full use of the parking time for charging. Therefore, it is possible to rely on the parking place to establish simple charging facilities and provide charging services, without building a large-scale centralized charging station, which can greatly reduce the cost. The charging mode of the whole vehicle or the replacement mode of the battery pack can also be decided according to the actual situation of the individual. The on-board battery capacity of private electric vehicles is small, the charging time will not be too long, the cost of the battery is low, and the way to supplement electric energy is as long as it is convenient for users.

In addition, for the charging station, the operation mechanism of the vehicle entering the charging station will also affect the power demand of the charging station. The more concentrated the time the vehicle enters the charging station, the greater the power load of the charging station and the greater the power demand of the charging station. Electric vehicles should make full use of the valley power stage of the power grid for charging, which can minimize the operating cost for vehicle owners, and the power grid company can adjust the bee valley difference of the power grid.

1.1.2 business model of electric vehicle charging station

At present, there are three main business models for the construction and operation of electric vehicle charging stations outside China: public charging station model, parking lot (or roadside) charging pile model, and battery replacement station model.

1. Public charging station mode

The direct charging of the charging station is similar to that of the gas station, which directly charges the electric vehicle without replacing the battery. Because direct charging requires a lot of space and special power supply facilities, the investment is large and it is difficult to recover the cost. Therefore, in addition to the government model behavior, it is difficult to carry out commercial promotion. In addition, direct charging takes a long time, fast charging takes 2-3 hours, and it will cause great damage to the battery.

(1) Main features. Public charging stations, similar to gas stations, are usually built on both sides of urban roads or highways. The charging station is composed of several charging facilities, which can provide electric energy for various electric vehicles in various ways, such as fast charging, slow charging and battery replacement. Smaller charging stations can generally charge 10 electric vehicles at the same time, while larger charging stations can charge 40 electric vehicles at the same time.

(2) Advantages. Charging stations can provide a variety of services for social electric vehicles, including fast charging and slow charging. Some charging stations can also provide battery replacement services; The charging speed is fast. Generally, the battery can be fully charged within dozens of minutes by using the fast charging method; Due to the public nature of the charging station, the equipment utilization rate is higher than that of the charging pile in the parking lot. The biggest advantage of public charging stations is fast charging, but the current fast charging technology needs to be improved in order to further shorten the charging time and reduce the damage to the battery life.

(3) Disadvantages. The charging station covers a large area, and the larger charging station covers more land than the general gas station, even compared with the parking lot. Due to the large area and the increasing shortage of urban land, the number of charging stations in big cities is limited and the network density is low. Due to the need to be equipped with a variety of charging equipment, the construction is difficult and the one-time investment is large. The average investment of the State Grid Corporation of China in building a new charging station is about 3million yuan.

2. Parking lot (or roadside) charging pile mode

Charging pile is a device to supplement electric energy for electric vehicles, and its shape is like a parking meter. One charging pile can charge two electric vehicles at the same time, and the full charge time is 6-8 hours. The charging pile can realize time, electricity and amount charging.

(1) Main features. Charging piles are usually built in public parking lots, residential parking lots, shopping malls, or beside highways, or in private garages. The charging pile has the characteristics of small power and flexible distribution of points. It mainly adopts the slow charging mode, and has the man-machine operation interface and self-service function.

(2) Advantages. Charging piles are built in parking lots or roadsides, covering a small area. Charging piles built in garages and residential areas do not occupy public land at all; The construction difficulty is small, the one-time investment is small, and the construction cost of a single charging pile is 20000-30000 yuan.

(3) Disadvantages. The charging speed is slow, and the charging pile adopts the slow charging method, and the charging time is 5-10 hours; Due to the long charging time and the special nature of some charging piles, the equipment utilization rate of charging piles is lower than that of charging stations; It cannot meet the charging demand of emergency and long-distance driving. Although it is easy to build a single charging pile, the charging pile needs to form a network to meet the needs of the popularization of electric vehicles, and it takes a long time to improve the whole charging network.

3. Power station replacement (battery rental) mode

Battery leasing refers to the separation of electric vehicles and battery sales. Some manufacturers sell naked electric vehicles, and some manufacturers operate battery leasing business. The central government grants subsidies to battery leasing enterprises. Battery leasing enterprises rent batteries for electric vehicles to private users at the price after deducting subsidies, and provide battery maintenance, maintenance, replacement and other services. Xiao battery is only rented but not sold. The electric vehicle directly replaces the fully charged battery at the charging station to realize charging, and settles the actual charge of the previous battery.

(1) Main features. Users rent batteries from battery rental companies. The replacement station provides users with services such as battery replacement and battery maintenance. The batteries are centrally charged in the charging center. Due to the heavy weight of the battery pack, there are strong professional requirements for replacing the battery, so it is necessary to allocate professionals to quickly complete the replacement, charging and maintenance of the battery with the help of professional machinery.

(2) Advantages. The requirements for battery replacement stores are very low, only 2-3 parking spaces are required, and the floor area is smaller than that of the charging station; The main equipment of song battery replacement station is battery disassembly and installation equipment, which has less electrical equipment, less construction difficulty, and less one-time investment than the charging station; The speed of replacing the battery is fast, and the time of replacing the battery is generally 5-10 minutes. In the future, with the progress of technology, the time required to replace the battery will be less than the fast charging time; The battery replacement mode has low requirements for stores and is easy to deploy in a large area of the city.

From the perspective of commercial operation, the replacement arrow battery mode belongs to the new energy logistics mode. The battery replacement mode is conducive to the large-scale and standardized production of battery manufacturers, the large-scale procurement and intensive management of energy supply enterprises, and will significantly reduce the total operating cost. As a relatively independent intermediary operator, the energy supply enterprise is conducive to the government to implement more targeted support and preferential policies, such as electricity price policy, battery purchase subsidy policy, etc. it is easy to establish a clear financial profit model. It can obtain higher return on investment than simply providing charging services, and has a broader development space. In addition, this mode is also very beneficial to the safe and economic operation of the power grid. Centralized charging is convenient for unified dispatching, management and monitoring, can maximize the role of peak shaving and valley filling, improve the load rate of the power system, minimize the adverse effects of harmonic pollution on the power grid, and is conducive to the safe and stable operation of the power grid and the optimal utilization of power resources.

(3) Disadvantages. The mode of power exchange station (battery leasing) requires the state to establish a unified battery standard. The power battery installed in electric vehicles must be removable and replaceable, and the requirements for the standardization system of the automotive industry are very high. At present, the standard system of electric vehicles in China is still far from perfect. Automobile manufacturers and battery manufacturers are basically fighting on their own, and battery specifications vary greatly; The battery replacement mode involves battery leasing, charging, distribution, measurement, replacement and other links, which are completed by multiple enterprises, and the work is complex.

Battery replacement station mode is an ideal business mode in theory. Some cities in China have carried out pilot operations, but there are some difficulties in large-scale promotion of this mode in the short term, which are mainly reflected in the following three aspects.

(1) In terms of management, China is in the early stage of the development of the electric vehicle industry. The battery technology is not yet mature, and the performance and quality of various batteries are very different. It is very difficult to unify the battery standard. This is not only the standardization of batteries, but also the standardization of electric vehicles. It is a huge system engineering, involving the interests of automobile manufacturers, battery manufacturers, replacement station operators and other aspects.

(2) In terms of technology, in order to ensure that the battery can be replaced, all batteries must have good consistency. It is not only necessary to unify the battery interface standards, but also the size, specification, capacity, performance, etc. under the current situation that Chinese battery manufacturers are fighting on their own, it is difficult to unify the consistency of all battery manufacturers in the production of batteries in the short term.

(3) Battery circulation. In the process of battery replacement, there will be differences in the old and new degree and residual energy of the battery, which will bring the problem of how to measure and charge when replacing the battery.

In short, there is still a long way to go before the battery replacement station model becomes a mature business model. Only when China’s electric vehicle industry develops to a more mature stage, it may become the mainstream business model of the charging industry.

4. Development trend of business model of electric vehicle charging station

The above three models are not mutually exclusive, but competitive and complementary. In the future, a complete charging network system should be composed of charging stations, charging piles and replacement stations to provide convenient and efficient services for electric vehicle users.

There are no technical problems in the construction of public charging stations, and the equipment investment cost is not high, but it occupies too much land resources, and the land acquisition cost cannot be underestimated. In the short term, in the initial stage of the development of electric vehicles, when the construction of charging facilities has just started and a complete charging network has not yet been formed, it is necessary to quickly build a number of public charging stations, which can produce a good demonstration effect and advertising effect, and promote the popularization of electric vehicles as soon as possible. However, in the long run, public charging stations cannot be the ultimate solution for electric vehicle charging, nor should they be the main charging method. Public charging stations should be positioned to mainly meet the emergency charging needs of various social vehicles and provide fast charging services, which can effectively reduce the floor area of charging stations and improve equipment utilization.

From the perspective of convenience and resource conservation, ordinary electric vehicles are parked most of the time, and the charging piles built in parking lots and roadsides can basically meet the needs of ordinary electric vehicles for conventional charging; And replacing charging stations with a large number of charging piles can also save valuable land resources. Therefore, in the long run, the dominant conventional charging mode in China should be slow charging, and parking lots and roadside charging piles will become the dominant charging facilities. Build charging piles in all places where parking can be achieved. Each time an electric vehicle is added, a new charging pile will be built, and the number of charging piles will be equal to the number of electric vehicles.

In foreign countries, home charging is the most frequently used way to charge electric vehicles. Only outside the home, do you need to rely on public charging facilities. At present, from the experience of Tel Aviv in Israel and Tokyo in Japan, charging piles in parking lots and communities are used most frequently, and charging stations have not become the preferred choice of most electric vehicle users.

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