Two major requirements faced by motors under the 800V architecture

Slow charging and difficulty in charging are still the "Achilles heel" that prevents electric vehicles from subverting fuel vehicles. In order to solve this problem, high-voltage platform technology and the accompanying super charging piles are currently one of the most promising solutions. Limited by the voltage withstand capability of silicon-based IGBT power components, the 400V voltage platform was commonly used in electric vehicle high-voltage systems. In charging piles based on this voltage platform, if you want to further increase the charging power and shorten the charging time, you need to increase the voltage platform from 400V to 800V, 1000V or even higher levels to achieve the expansion of the high-voltage system.

High-voltage fast charging requires the simultaneous upgrading and joint development of supporting facilities in the three major directions of "vehicle voltage, battery, and charging pile" to be realized.

▍The first year of high-voltage charging piles

Data shows that from January to June this year, my country’s charging infrastructure increased by 1.301 million units. Among them, the increase of public charging piles increased by 228.4% year-on-year, and the increase of private charging piles increased by 511.3% year-on-year.

In the first half of the year, the increase in both public and private charging piles significantly exceeded that of the whole of last year. There is strong policy support for charging piles, and high-voltage fast charging is one of them, so 2022 is called the first year of high-voltage fast charging for new energy vehicles. Slow charging and difficult charging have always been problems faced by new energy vehicles. In order to break through this bottleneck, the automotive industry chain has accelerated the pace of electrification transformation; through 800V high-voltage fast charging technology, the two major shortcomings of battery life and charging efficiency have been solved. 800V high-voltage fast charging Fast charging has subsequently become an internet celebrity technology for major pure electric models. After entering 2021, the high-voltage fast charging route is favored by more and more OEMs. First, international giants such as Hyundai and Kia released 800V platforms. Later, domestic OEMs such as BYD, Great Wall, GAC, and Xpeng also launched or planned to launch 800V platforms.

High-voltage fast charging experience will become an important standard for differentiated experience in the electric vehicle market. The first half of new energy vehicles focuses on motors and batteries, while the second half focuses on charging piles and intelligence.

▍Silicon carbide 800V

With 800V high voltage, the loss of electrical energy in the circuit will be less than the traditional 400V system, and the charging power will be faster due to the increase in voltage. Among the power semiconductor devices that currently meet automotive grade standards, the most mainstream silicon-based IGBTs have a withstand voltage rating of 600-750V. However, there are not many high-voltage IGBT products that can be used on the 800V platform, and there are still some with high losses and low efficiency. shortcoming

At this time, the advantages of silicon carbide power tubes are revealed. Silicon carbide is a wide bandgap device, and its breakdown field strength is ten times that of silicon material devices. Therefore, it can achieve higher withstand voltage with smaller size. Currently, Silicon carbide power tubes can support a MOSFET blocking voltage of 1700V, making them ideal for high-voltage applications. In addition, silicon carbide devices have low on-resistance and small leakage current when turned off, which can significantly improve the efficiency of power modules. The thermal conductivity of silicon carbide devices is three times that of silicon-based devices and can withstand higher operating temperatures, thus reducing heat dissipation requirements. ; Silicon carbide devices have extremely low reverse recovery current and can perform switching operations at 3 to 5 times the operating frequency of corresponding silicon-based devices, thereby reducing the performance requirements for capacitors and magnetic components, and can be used with lighter weight and lower costs. Low capacitance and inductance to implement corresponding modules, which is very meaningful for electric vehicles to reduce weight and extend battery life.

By replacing silicon-based IGBTs with silicon carbide devices, it can not only improve the overall performance of the device, reduce the difficulty of heat dissipation design, but also reduce the cost of the entire vehicle. Although silicon carbide power devices are more expensive than silicon power devices such as IGBTs, due to their low loss and light weight, they can effectively increase the battery life of the vehicle, thereby reducing the number of battery modules to be assembled and reducing the cost of the vehicle.

▍Car companies gradually adopt 800V silicon carbide high-voltage platform

In August, reservations for the new energy vehicle Xpeng G9, which will be officially launched in September, began. One of the highlights of this car is the Xpower 3.0 power system used. All components are 800V-level. This is the first mass-produced car in China based on the 800V high-voltage SiC platform. In order to increase the charging speed, Xiaopeng not only The compatible voltage of the electric drive system has been increased, and the compatible current has also been greatly increased, now reaching more than 600A. We should remember from high school physics that power is equal to current times voltage, then the charging power supported by this car is 600A times 800V, which is equal to 480kW! Recently, Xpeng Motors released Xpeng S4 ultra-fast charging, which is the first mass-produced 800V ultra-fast charging platform in China. The fast charging and Xpeng G9 can achieve "vehicle-pile combination" to achieve the fastest charging. 5 minutes, increase driving range by 200km

The supplementary effect and efficiency of this charging speed far exceed those of charging piles currently on the market. In addition to Xpeng Motors, many companies in the industry are actively deploying high-voltage fast charging. In 2022, the JiFox Alpha S, Xpeng G9, and Great Wall Mecha Dragon equipped with 800V systems will be launched one after another. According to analysis by Soochow Securities, the implementation of the 800V-level high-voltage solution will enable the charging power to exceed 400kW. It is expected that charging will take 5 minutes and the driving range will be increased by 200 to 300km, which will greatly alleviate charging anxiety. In 2019, car companies began to pay attention to 800V high-voltage solutions. From 2021 to 2022, more high-end models of car companies will adopt 800V fast charging. From 2023 to 2024, new platforms will continue to use 800V high voltage.

▍Sunwanda super fast charging battery will be mass-produced within this year

On September 3, Sunwanda's super fast charging power battery product launch conference and supplier conference was held at the Zaozhuang Convention and Exhibition Center. Sunwanda entered the power battery fast track with its latest fast charging products. At the press conference, Sunwanda Electric Vehicle Battery Co., Ltd. released its super fast-charging power battery product - SFC480. The product has a maximum charging power of 480kW and can achieve a range of 200km in 5 minutes and 400km in 10 minutes. A single charge can last Up to 700km, and provides 10-year warranty

It is reported that the super fast-charging battery technology released by Sunwanda is mainly derived from Sunwanda’s accumulation in HEV high-rate battery technology, and it also carries out technological innovations in materials, structures, processes, etc.

1 In terms of material innovation, Sunwanda’s super fast-charging battery uses a high-voltage, low-cobalt Ni60 cathode system, and adopts composite coating and R element doping technology solutions to improve the product performance of the cathode material, so that the battery also has high energy density and fast charging and high safety performance

2. In terms of process innovation, composite porous electrode technology has been developed, which increases the thickness of the cell electrode by about 15% compared with traditional processes to obtain higher energy density and better dynamic performance.

3. In terms of structural innovation, it adopts lamination & non-connector link technology, and 100% of the battery cells adopt CT detection technology to achieve a lamination accuracy of ±0.1mm. At the same time, CCD online detection is used to prevent the defective rate from flowing out, further ensuring the lamination accuracy; using The non-connecting piece connection technology reduces the internal resistance of the battery core by 3% and reduces the overcharge temperature rise by 2°C.

At the same time, this super fast-charging battery also introduces a new generation of 3D liquid cooling technology at the system level, achieving an energy retention rate of more than 85% at low temperatures of -20°C, a volume utilization rate of more than 72%, and no heat diffusion in all products. At the same time, the system also has high scalability, supports upright and inverted cell configurations, and can also be expanded to CTB/CTC platforms.

▍Motors face two major requirements under the 800V architecture

Under the traditional 400V architecture, permanent magnet motors are prone to heat and demagnetization. Under the 800V architecture, the motor faces two major requirements: anti-corrosion bearings and enhanced insulation performance. The technical route adopts flat wire + oil cooling technology to improve motor power density and efficiency. Therefore, the material side focuses on anti-corrosion and insulation, and the technology side focuses on flat wires. The application range can be expanded by more than three times.

▍High voltage DC relay is the core component of new energy vehicles