I. Development Trends of DC Fast Charging Scenarios
1.1 From Single Centralized Charging Stations to Diversified Scenario Collaboration of "Centralized + Distributed"
In the past, DC fast charging stations were predominantly centralized, occupying key urban and transportation locations. This type of station has high requirements for site selection and power capacity. Due to the current status of lithium battery technology, the time required for short-term DC fast charging (to full capacity) still cannot match the refueling speed of fuel-powered vehicles. For regular passenger car charging, it generally takes 1.5 to 2 hours to charge from 10% to 100% SOC. Therefore, limited by charging experience (duration), centralized charging stations mainly cater to operational vehicles (which require continuous high-power charging to maintain business continuity) and a small proportion of private car owners. According to operational data from major charging operation platforms and data monitoring platforms, the utilization rate of DC charging piles in centralized fast charging stations remains low, generally below 15%. While the proportion of new energy vehicles is a realistic factor, it is undeniable that the site selection and target user positioning of most charging stations are insufficient, resulting in certain resource waste.
Destination distributed charging stations will be an effective supplement to improve the charging network. If traditional centralized charging stations can be described as "users looking for piles", then destination distributed charging stations will be "piles waiting for users". Charging users can charge while staying at the destination (usually more than 1 hour), with no high requirement for charging speed (a certain amount of energy supplementation is sufficient), meaning the charging power of the piles is mainly 20-30kW (for passenger cars). Meanwhile, destination distributed charging stations have lower requirements for location and power capacity, making them easier to construct and suitable for widespread promotion.
1.2 Centralized Charging Stations Subdivided by Application Scenarios (Environments) into "Centralized Charging Stations for Ordinary Environments" + "High-Protection Centralized Charging Stations for Harsh Environments" + "Centralized Ultra-Fast Charging Stations (Liquid-Cooled) with Power Above 350kW"
As we all know, charging piles in practical on-site applications generally suffer from frequent failures caused by environmental factors. The main reason is that the core component of charging piles, the charging module, has an IP20 protection level, which provides weak protection against harsh environments (sand and dust, salt spray, condensation, conductive particles). At the same time, charging modules have high power density and generally operate under high voltage and large current conditions, further increasing their sensitivity to harsh environments. Therefore, it is necessary to separate charging stations in harsh environments from those in conventional environments and adopt special design forms for such stations (charging piles). Currently, there are two feasible upgrade solutions for charging stations in harsh environments: a) adopting IP65 independent air duct charging modules; b) adopting IP20 charging modules + heat exchanger/air conditioning cooling solutions.
With the continuous improvement of society's demand for electric vehicle charging experience (speed), continuous changes are taking place in batteries, vehicle manufacturers, and supporting charging pile system solutions. Guided by vehicle manufacturers, high-voltage battery platforms (above 800V) adopt new battery technologies to support 4C~6C charging, requiring supporting "super charging piles" (hereinafter referred to as "ultra-fast charging piles") with power above 350kW and single-gun charging current up to 500A. Regarding the charging modules in ultra-fast charging piles, industry participants generally agree that the "liquid-cooled module" is an ideal technical solution.
II. Development Trends of DC Charging Pile Technology
After more than ten years of development and full competition in the DC charging pile industry, the current market application status reveals several major problems: 1. The technical route is relatively single, with more than 90% adopting direct ventilation cooling solutions. From the application effect, it cannot meet the requirements of environmental adaptability and high reliability for diversified application scenarios. 2. Market competition is highly focused on price competition rather than "product value innovation" competition. This has led manufacturers to generally reduce costs, resulting in decreased product reliability. 3. The single technical route has led to insufficient environmental protection capabilities of charging piles, resulting in heavy maintenance workload and high maintenance costs, ultimately leading to high TCO (Total Cost of Ownership) throughout the entire life cycle.
2.1 Trend of Increasing Capacity of Charging Pile Systems in Centralized Stations
With the general improvement of electric vehicle battery capacity, there is also a general demand for increasing the single-gun capacity of charging piles. Taking the Class A electric vehicle e-Golf as an example, it has a battery capacity of 35.8kWh and can support a maximum charging power of 1C 35.8kW, meaning the maximum charging power demand of entry-level Class A models in a depleted state has exceeded 35kW.
From the current actual market application, the 120kW dual-gun is currently the most widely installed charging pile specification in the market, with a trend of further evolution to 160kW dual-gun capacity. The fundamental reason lies in the improvement of power battery density and charging rate. The demand for increasing the capacity of charging pile systems will also lead to the demand for configuring charging modules with larger granularity.
2.2 Trend of High-Voltage Charging Piles
An important factor affecting the popularization speed of electric vehicles is the improvement of charging experience. The two most important factors affecting charging experience are the convenience of finding charging stations (charging piles) and charging speed. Currently, it generally takes 1.5 to 2 hours for electric passenger cars to charge from depleted (10% SOC) to full (100% SOC). This charging time still has significant room for improvement and is gradually approaching the 15-minute refueling time of fuel-powered vehicles.
The high-voltage trend of electric vehicle electrical platforms is a current technical evolution direction of vehicle manufacturers. Under the same charging current, high-voltage battery packs can support higher charging power and shorter charging time. Foreign brand Porsche launched the 800V Taycan model in 2020, and domestic brand BAIC launched the Arcfox supporting 800V charging in May 2021. Meanwhile, major domestic vehicle manufacturers such as Xpeng, NIO, and GAC have announced plans for high-voltage models above 800V. It is expected that the number of high-voltage models above 800V will gradually increase within the next 2 years.
Under the trend of electric vehicle high-voltage evolution, there is an urgent need for charging piles to increase the upper limit of charging voltage to 1000V to support high-voltage models that will be widely used in the future. According to theoretical analysis, for a 90kWh lithium battery (with a range of approximately 700 kilometers), charging with a high-voltage platform of 1080V/max 500A can achieve a maximum charging power of 540kW and 6C charging capacity, enabling the battery to be fully charged in 10 minutes. According to market information, vehicle manufacturers such as GAC, Xpeng, and NIO are already planning high-rate charging battery packs and new models (supporting 4C～6C).
Based on this market development demand, State Grid Corporation of China has clearly required in its charging pile centralized procurement project in May 2021 that the winning charging pile specifications must support a maximum charging voltage of 1000V, which is undoubtedly an important market signal.
2.3 Requirements for High Reliability and High Compactness Design of Destination Charging Stations
There is a widespread market demand for destination charging stations, which require new types of small DC charging piles to meet short-term DC energy supplementation. Such scenarios generally face: 1. Limited installation space; 2. High aesthetic requirements for the appearance of chargers (especially in commercial space environments); 3. High requirements for environmental protection/reliability for models installed outdoors; 4. Unattended operation in most cases, which in turn places high demands on high reliability/maintenance-free performance of products. The above four major application requirements put forward two major design requirements for small DC chargers: high reliability and high compactness, which pose high requirements for charger R&D and production enterprises in design.
III. Development Trends of DC Charging Pile Module Technology
As the core key component in the charging pile system, the technical scheme, performance, and reliability of the charging module directly affect the overall performance of the charging pile system. Looking back at the development over the past ten years, in the early stage, the market adopted existing technical solutions (IP20 direct ventilation technology from the communication power supply industry) through "copy-paste" and directly inherited them into the charging pile industry. However, after more than ten years of market development, the unique application environment of charging piles has proven that the traditional single technical solution cannot support the industry's development towards healthier and more advanced goals. At this time, it is necessary to conduct innovative thinking on the technical scheme of the charging module itself and design new technical solutions to promote the industry's development towards a healthier and more advanced direction.
3.1 From a Dominant 20kW Market to a Diversified Configuration Market of 20/30/40kW
In the current domestic market, 20kW modules account for approximately 60% of the market capacity, with the remaining largely occupied by 30kW modules and some 40kW modules. In recent years, with the improvement of electric vehicle battery capacity and charging rate, there has been an obvious actual market development trend: the dominant 20kW market is gradually evolving towards diversified specifications of 20kW, 30kW, and 40kW.
The main reason is that charging piles with different system powers and different charging gun power distribution requirements require charging modules with different optimal power granularities. Therefore, for the standard specifications of charging modules, it is advisable to formulate a series of charging modules with different capacities.
3.2 30kW/40kW Charging Modules Should Adopt a Unified Size/Unified Interface Design Scheme
With the continuous evolution of charging module technology and the gradual maturity of market application scale, the design direction of charging module products is also continuously improving towards high reliability and high power density. For the clear market demand for 30kW/40kW charging modules, it is necessary to reduce the repetitive design work of charging piles due to module specification iteration, which was caused by insufficient consideration of long-term development compatibility in the process of charging pile standard upgrading and evolution in the past. Therefore, 30kW/40kW modules should be designed with the goal of uniform structural size and interface size from the initial design stage.
3.3 Upper Limit of Output Voltage Range from 750V to 1000V High-Voltage Application
The continuous advancement of vehicle manufacturers' high-voltage electrical platforms has promoted the upgrading of supporting charging pile infrastructure. A maximum output voltage of 1000V has formed a consensus in the charging module industry, and major charging module manufacturers have gradually launched 1000V high-voltage charging module specifications.
Due to the high power density, higher voltage, and larger current of 30kW/40kW modules, greater challenges are posed to product reliability. Some manufacturers that launched 30/40kW modules relatively late still need a certain amount of market application over a period of time to verify product reliability.
3.4 Promotion and Application of Independent Air Duct Design Scheme/IP65 High-Protection Scheme
In the early stage of market development, mature IP20 direct ventilation technology products supported the charging industry through nearly 10 years of development. During this process, the inherent outdoor, high-temperature, sand and dust, moisture and other environmental factors of the installation and use environment of charging piles have posed great challenges to product reliability. Since the technical route itself (direct ventilation) is difficult to meet the application requirements of harsh environments, charging pile products generally suffer from high failure rates and high operation and maintenance costs. Coupled with the price decline after full competition (while still needing to bear continuous maintenance costs), it has caused great pressure on the business development of most pile enterprises. Some manufacturers in the industry claim to have adopted an improved "semi-independent air duct" scheme. After analyzing the details, it is actually using potting technology to cover and protect the components on the board surface, while the higher components above the board surface will still face the impact of dust, moisture, and salt spray for a long time. Although it can delay the occurrence of failures to a certain extent, it does not fundamentally solve the environmental protection problem of internal components.
In this predicament, individual manufacturers have launched an innovative "independent air duct technical scheme". Different from the conventional IP20 direct ventilation technology, the independent air duct technology divides the module into upper and lower layers through innovations in structural design and layout of internal key components. The upper layer encapsulates components sensitive to the environment (sand and dust, moisture, salt spray, etc.), such as capacitors, semiconductors, and magnetic components; the lower layer is composed of components not affected by the environment, such as radiators, and the air duct at the lower part is more unobstructed, ensuring heat exchange efficiency.
Taking a 120kW charging pile as an example, comparing the overall TCO (Total Cost of Ownership）