800v charging station - unlocking longer range electric vehicles

Among the top 10 power battery companies in China, BYD, has also begun to study the 800v technology platform for vehicles in its self-developed models.

Then, how can the quantitative change of the rising voltage platform make it convenient for electric vehicles to replenish energy? This article will introduce the 800v charging station that many car companies are laying out.

How does charging station work?

When the charging gun head is connected to the vehicle end, the charging pile will provide low-voltage auxiliary DC power to the vehicle end to activate the built-in BMS (battery management system) of the electric vehicle.

After activation, the car end is connected to the pile end, and the basic charging parameters such as the maximum charging demand power of the car end and the maximum output power of the pile end are exchanged.

After the two parties are matched correctly, the BMS (battery management system) at the car end will send power demand information to the charging pile. The charging pile will adjust its own output voltage and current according to this information, and officially start charging the vehicle.

Therefore, in order for the 800v charging station to charge electric vehicles, it is also necessary to develop an 800V platform at the vehicle end, and to select and match high-voltage components, including battery systems, electric drive systems, charging systems, and power devices.

Why choose 800v charging station?

Fast charging has two technical routes of high current and high voltage, and high voltage fast charging has more advantages.

Fast charging has two technical routes of high current and high voltage:

Theoretically, according to W=Pt, if the charging power is doubled, the charging time will be halved;
According to P=UI, if the voltage or current is doubled, the charging power can be doubled.

Compared with high-current fast charging, high-voltage fast charging generates less heat and lower loss.

The disadvantage of the high-current route is that according to Q=I²Rt, the higher the current, the greater the power loss, and the loss is reflected in the form of heat, which increases the pressure on thermal management.

In addition, high current requires cables with higher ampacity and larger wire diameters, which will also increase the cost and weight of cables.

Tesla currently adopts a high-current solution, while more car companies are turning to high-voltage solutions. At the same time, some car companies have turned to battery replacement solutions.

Battery swap station vs charging station

Although 800v fast charging can quickly increase the charging speed and relieve battery life anxiety. However, it will take some time for 800v charging stations to become popular.

On the vehicle side, components including batteries, electronic controls, and even air conditioners need to be adapted to the 800V high-voltage system, which requires time and technical support. Therefore, 800V fast charging still has some limitations in practical applications.

Compared with the 800v charging station, the battery swap mode can also extend the mileage of the vehicle by quickly replacing the battery, and alleviate battery life anxiety to a certain extent.

In addition, with the maturity of the battery swapping station business model, this energy replenishment method is becoming more and more convenient

However, there are also some problems in the battery swap mode. The construction of power stations requires a lot of capital and technical support. Secondly, different brands of vehicles use different battery standards, which also brings certain restrictions to the battery swap mode.

To sum up, both 800V fast charging and battery swapping modes have their advantages and disadvantages.

In the future, with the continuous development of technology and the continuous expansion of application scenarios, these two energy supplement modes are expected to be more widely used and promoted.

Advantages of 800v charging station

Electric vehicles using an 800V high-voltage platform can greatly improve the charging speed.

Take Xiaopeng S4 super charging pile as an example. This 800v charging station fully matches the Xiaopeng 800V high-voltage platform model, and the maximum charging power can reach 480kW.

According to the description, when matched with the Xiaopeng G9 equipped with a 4C battery pack, it can charge the remaining power from 10% to 80% within 15 minutes.

The 800V high-voltage platform realizes “burden reduction” for the wiring harness system. Under the same power, higher voltage brings lower current.

This means that the wiring harness system does not need to use higher-cost wiring harness materials and heavier shell materials for high current.

Not only the volume and weight of the wiring harness are reduced, but also the loss of the internal resistance of the circuit is lower.

What configurations of the 800v charging station need to be upgraded?

In the case of overcharging, the charging module needs to be upgraded, and the charging gun, cable, DC contactor, and fuse need to be re-selected.

Under the high-voltage overcharging situation, the voltage will increase from 400V to 800V or even 1000V, and the power will also develop from 120kW to 480kW.

At this time, the charging module will be upgraded in two aspects: magnetic components and power devices:

1) In order to adapt to the current low-voltage stock charging pile, the charging pile needs to be equipped with a DC/DC boost module to increase the demand for magnetic components;

2) SiC-based power devices can achieve a higher switching frequency than Si-based, thereby achieving higher power density. It is expected that SiC-based power devices will accelerate market penetration in the field of DC charging piles.

Overcharging puts forward higher requirements for thermal management of the pile end, and the cost of using liquid cooling devices for the host + machine gun increases

A large amount of electric heat generated during overcharging requires an additional liquid cooling system.

When charging at a high power of 400kW and above, the charging equipment will heat up rapidly in a short period of time, which may cause thermal safety problems, and the traditional air cooling cannot meet the heat dissipation requirements of the equipment.

Therefore, both the host and the machine gun need to be equipped with a liquid cooling system with better heat dissipation.

Summary

There are still many corresponding supporting problems to be solved for 800V high-power charging, not just the problem of charging piles.

800V high-power charging has higher requirements on power conditions, and some places need power transformation to be suitable for new development.

At the same time, battery companies also need to develop high-voltage battery suitable for 800V high-power charging.