What are the important components of an EV charging station?(Part 1)

What are the important components of an EV?charging station? What roles do each of the components play? Below, I will briefly share the 6 major components of the charging station, hoping to help someone."

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1. Charging Module

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The charging module, also known as the power module, is the "heart" of the charging station, accounting for approximately 50% of the hardware cost of the charging station, and the hardware cost accounts for approximately 90% of the total cost. The charging module plays the role of converting alternating current into direct current in DC charging stations, which is related to the overall performance and charging safety of the charging station.

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2. Onboard Power Supply

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2.1 Overview

The biggest difference between new energy vehicles and traditional fuel vehicles lies in the "Three Electric" system:

2.1.1 Power Battery Assembly, including battery cells, battery packs, battery management systems(BMS), etc.;

2.1.2 Motor Assembly, including drive motors, motor controllers, etc.;

2.1.3 Control Assembly, including onboard chargers, onboard DC/DC converters, high-voltage distribution boxes, etc.

Among them, the onboard charger and onboard DC/DC converter are collectively referred to as the onboard power supply.

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2.2 Generally, the onboard power supply includes:

2.2.1 Onboard Charger(OBC), which refers to the charger installed on the vehicle for converting grid voltage efficiently into battery pack voltage, converting input alternating current into direct current, and completing charging. In other words, the OBC is only required when charging with alternating current (slow charging).

2.2.2 Onboard DC/DC Converter, which refers to converting the high-voltage direct current input from the electric vehicle battery into low-voltage direct current for powering low-voltage electrical equipment such as air conditioning, lighting, windshield wipers, electronic instruments, and safety airbags.

2.2.3 Integrated Onboard Power Supply Products, which refers to the integration of multiple components such as the onboard charger and onboard DC/DC converter to form a more compact, precise, and cost-effective integrated onboard power supply product.

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2.3. High-Voltage Fast Charging Trends for Onboard Power Supply:

2.3.1. Integration: Through the sharing of certain circuits and control chips, materials are conserved, volume and weight are reduced, and costs are lowered. This facilitates software development under a unified architecture, enhancing efficiency, reducing the number of components, simplifying production management, improving production efficiency, and reducing the pressure on after-sales service. Physical integration is currently common; however, some manufacturers adopt magnetic integration schemes. While maintaining output performance, magnetic integration significantly reduces material usage, effectively lowering costs and increasing efficiency.

2.3.2. Bi-Directional Charging: Bi-directional OBCs meet the needs of new energy vehicles for bidirectional charging and discharging, including Vehicle-to-Load (V2L), Vehicle-to-Vehicle (V2V), Vehicle-to-Grid (V2G), and other applications.

2.3.3. High-Voltage Trends: OBCs are evolving towards higher power levels such as 11kW/22kW.

2.3.4. Third-Generation Semiconductor Applications: The substitution of traditional silicon-based materials with silicon carbide in vehicle power sources is a significant trend. Third-generation semiconductor materials possess advantages such as high power characteristics, efficiency, low losses, and high-frequency properties, making them more suitable for manufacturing high-temperature, high-frequency, high-power, and radiation-resistant devices.

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2.4. Potential Disadvantages for Onboard Power Supply under High-Voltage Fast Charging Trends:

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As mentioned earlier, OBCs are only required when charging with alternating current. Therefore, in the medium to short term, the impact of DC fast charging on OBCs is not significant. However, in the long term, the widespread adoption of high-voltage fast-charging DC stations will to some extent replace OBCs. In fact, in 2021, the NIO ET7 model for the first time eliminated the AC charging port, and subsequent new models followed this design. In the future, for household AC charging stations, there is also a possibility of migrating OBCs from vehicles to within the charging station.

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3. Distribution System

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The distribution system of new energy vehicles effectively protects loads and batteries through the coordinated operation of relays and fuses. With the significant increase in voltage and current in 800V architecture, there are elevated requirements for relays and fuses.

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3.1. Relays

Relays are automatic switching components that play a role in circuit control and protection. They are essential components for electrical automation control and protection.

High-voltage DC relays are core components for new energy vehicles.

Traditional gasoline cars use 45 12V low-voltage relays, with a unit price of approximately 3-4 yuan, and the total value per vehicle is around 140-180 yuan. In new energy vehicles, in addition to the 45 automotive relays, typically, 5-8 high-voltage DC relays are also needed. Currently, the unit price is around 80 yuan, and the total value per vehicle for high-voltage DC relays is approximately 400-640 yuan.

In high-voltage architectures, relays may trigger more severe arcing when cutting off circuits. Therefore, there are increased requirements for product voltage resistance levels, current-carrying capacities, arc extinguishing capabilities, and service life. It is estimated that the total value per vehicle for high-voltage DC relays will reach 450-800 yuan in the future, with an increase of about 12%-25%.

3.2. Fuses

3.2.1 Overview

Fuses are devices for overcurrent protection in circuits, connected in series. When a circuit is short-circuited or overloaded, the heat generated by the overcurrent melts and vaporizes the fuse element, creating an opening. The opening generates an arc, and the fuse extinguishes the arc to cut off the fault circuit, thus providing circuit protection.

Under similar conditions, fuses can interrupt currents tens of times greater than other types of switch protection devices. Moreover, the maximum current and fault energy passed through fuses are less than one percent of those of other protective devices, highlighting the irreplaceability of fuses.

3.2.2. Demand Driven by New Energy Electric Vehicles

Vehicle fuses are divided into low voltage and high voltage categories.

Low-voltage fuses typically operate at voltages below 60VDC, mainly protecting low-voltage loads in vehicles (such as headlights, power windows, windshield wipers, etc.), and are used in both gasoline and electric vehicles.

High-voltage fuses are mainly used in new energy vehicles, operating at voltages generally between 60VDC and 1500VDC. They mainly protect the main circuit (battery high current charging and discharging, vehicle drive circuit), auxiliary circuit (air conditioning, PTC heating, slow charging, etc.), and the direct current side circuit of charging stations.

Under the trend of high-voltage fast charging, there is a need for excitation fuses or intelligent fuses to provide active protection:

Excitation fuses: They can actively cut off fault currents when the excitation device is triggered by a control signal, providing protection even before a fault occurs. Traditional fuses can only provide protection after a fault current occurs, resulting in higher power consumption and weaker protection effectiveness.

Intelligent fuses: They represent a further upgrade of excitation fuses, offering customized protection characteristics based on requirements. They can automatically trigger protection actions or accept external control signals to actively disconnect, providing integrated active and passive protection.

-To be Continued-