Suppose, in front of you, there are two pure electric vehicles of domestic brands. One uses a battery from a Korean manufacturer and a motor from a European and American manufacturer, and is produced in cooperation with a Canadian foundry. In the other car, more than 80% of the core component suppliers are domestically produced, including its own company’s or domestically-made independent suppliers. So, which one would you choose?
Author | Wang Xiaoyu
The core technology is often discussed not only in the automotive industry, but also in any industrial product. In the past two years, there was a story on the Internet-“Billions of ballpoint pens are produced every year, but more than 80% of the materials for the pen tip and bead core are imported from abroad.”
Today we are all talking about electrification, which is an opportunity for China’s auto industry to “overtake on corners”.But do we really master all the key materials and production processes with the battery, motor, and electronic control technology at the core?
Domestically-made electric vehicles, don’t repeat the same mistakes as fuel vehicles.
1. The neglected motor
“Which battery do you use for this car?”-This is the question that consumers ask the most when buying new energy vehicles. It should be known that power batteries account for the highest cost in the three-electric system (battery, motor, and electronic control), and will directly affect the final performance of the product, so it is a key factor for users to consider when buying a car.
At this stage,Whether it is independent brands or foreign brands, they are vying to use Chinese-made batteries.
According to data from SNE Research, an energy market research organization, CATL’s market share in the first half of this year was 29.9%, ranking first in the world. LG’s energy solutions have a market share of 24.5%, ranking second. In addition, BYD ranked fourth, with AVIC Lithium Battery and Guoxuan Hi-Tech in seventh and eighth respectively.
In the field of power batteries, an iron triangle of China, Japan and South Korea’s competition for hegemony has formed. There are 5 Chinese companies on the list, 3 from South Korea and 2 from Japan. Among them, the market share of 5 Chinese companies is 43.2%.
But in fact, the power battery is only the energy storage unit on the car. The core component of the driving vehicle is the electric drive system where the motor is located, but it is often ignored by the outside world.
The electric drive of electric vehicles is mainlyMotor,reducerwithControllerIt consists of three parts. Among them, the most important part isMotor, Don’t look at its cost which only accounts for about 10% of the cost of the car. In contrast, the cost of electronic control accounts for about 11% of the total cost, and the cost of the battery accounts for about 40% of the total cost. However, the vehicle’s maximum speed, acceleration time, climbing ability and other vehicle performance are closely related to the drive motor.
The commonly used drive motors on the market are mainlyInduction asynchronous motorwithPermanent magnet synchronous motorTwo kinds.
Simply put, permanent magnet motors can ensure longer battery life, and induction motors can ensure stronger performance. Therefore, most domestic low-end electric vehicles will use permanent magnet synchronous motors to achieve longer cruising range. High-end electric vehicles are more willing to use induction asynchronous motors to meet stronger power performance.
But there is also a solution-“Front induction asynchronous, rear permanent magnet synchronous”The drive scheme of the new product not only guarantees long battery life, but also high performance. This kind of “mix and match method” is used on the dual-motor four-wheel drive version of the Tesla Model 3, as well as on the mid-to-high-end models of Weilai.
It can be said that the development of motors and batteries is somewhat similar. On the one hand, two technical routes coexist. The power battery is a ternary lithium battery and a lithium iron phosphate battery. Induction asynchronous motors and permanent magnet synchronous motors are almost similar. On the other hand, new materials are beginning to gradually promote technological changes and guide product progress.
Graphene and silicon-based materials have become key technologies for power batteries to enter the next era. In the drive motor, silicon carbide has become a key material for rising energy consumption, performance, and battery life.
2. The domestic supply chain is waiting to rise
Silicon carbide is the most typical third-generation wide-bandgap semiconductor material. It has the advantages of fast switching speed, high turn-off voltage and high temperature resistance. In electric vehicles, every current conversion in motor drive and battery management consumes energy, and silicon carbide devices can maximize the utilization efficiency of the energy output by the battery.
Regrettably,At present, the complete industrial chain of silicon carbide power modules is not independently controlled by China.
“The module itself is still imported, because China does not yet have such an industrial chain. The top-level substrate material is Cree. Wafers made in a Korean factory, modules made in Malaysia, and then sent to China. Then press-fitting in our Nanjing factory is such a process path.” said Zeng Shuxiang, senior vice president of Weilai Electric Drive and Battery Industrialization.
Simply put, the preparation process of silicon carbide power devices includes: SiC powder synthesis, single crystal growth, wafer cutting, grinding and polishing, epitaxy (coating), front-end process (chip preparation), and back-end packaging. Among them, the process of being stuck is “single crystal growth”.
Traditional silicon wafer production technology has been very mature. The raw materials only need to be heated to about 1400 ℃ to melt, and then a series of operations are performed to make wafers.
However, the production of silicon carbide is much inefficient, requiring the raw material to be heated to about 2800°C. In terms of melting point, thermal conductivity, and inertia, silicon carbide is a very difficult material to manufacture. So far, the yield rate of growth is less than 50%, and there is still a lot of room for improvement.
The global silicon carbide industry pattern presents a three-pronged situation of the United States, Europe, and Japan.
American companies account for 70%-80% of global silicon carbide production. The representative company is Cree (now renamed Wolfspeed Inc); Europe has a complete silicon carbide substrate, epitaxy, device and application industry chain, and the representative company is Infineon , STMicroelectronics, etc.; Japan is leading the development of equipment and modules, represented by Rohm Semiconductor, Mitsubishi Electric, and Fuji Electric.
Car companies are not very involved in the silicon carbide industry chain. At the earliest, Tesla used silicon carbide modules in the front and rear motor controllers of the dual-motor version of the Model 3. Later, BYD also used this technology in the high-performance version of the Han EV four-wheel drive, making it accelerate from 100 kilometers to 3.9 seconds.
In addition, Weilai ET7 will also be equipped with a silicon carbide electric drive system-this system is equipped with a front permanent magnet motor of 180kW and a rear induction motor of 300kW. It is the first SiC silicon carbide power module used by Weilai. It helps ET7 achieve stronger acceleration and longer battery life.
The ET7 accelerates from 100 kilometers to 3.9 seconds, which is the fastest acceleration model of Weilai. And in the case of a 150kWh battery pack, the comprehensive operating range cruising range exceeds 1,000 kilometers.
The impact of the application of silicon carbide on battery life and acceleration is only surface data. What NIO hopes to emphasize is its self-research and engineering capabilities. Zeng Shuxiang said:“We have full-stack manufacturing, motor assembly, motor winding, and process controller production equipment. These are also rare. These three core parts have self-manufacturing capabilities, which are the only ones in the world. Manufacturing capabilities.”
In fact, the high-power motors above 200kW in the current industry are gradually mature, and the external supply chain is relatively complete. Most domestic car companies will choose to purchase, which is a low-cost way.
Zeng Shuxiang believes that, first of all, NIO’s positioning of high-performance electric vehicles has a higher pursuit of performance, so the requirements for electric drives are relatively high. It is not easy to purchase mature products from outside; in addition, if you just do A late-stage verification development may require some compromises in the product, and NIO can increase the degree of freedom in the supply chain and product design through the R&D and construction of the full range of capabilities.
“The industry’s R&D resources are in short supply. If it’s an outsourcing, can your partner’s engineering resources guarantee what the entire industry lacks? For example, there is a lack of a test platform with a speed of 16,000 or more. Everyone is fighting. , You don’t have to rely entirely on the outside.” Zeng Shuxiang said, “This can increase the degree of freedom and ensure the differentiation of Weilai’s products and the time for product launches.”
The silicon carbide power module is the best example. Zeng Shuxiang said that if you don’t have R&D resources, you will have to wait until someone else has built an inverter or an electric drive assembly before you can buy it. “But there is no silicon carbide on the shelf today. For mass-produced electric drive assemblies or controllers, we made this by ourselves, which can be at least half a year to a year earlier than most of our friends.”
Three, don’t just stare at the power battery
The competition of pure electric vehicles has shifted from the original battery life competition to a higher level of competition. There is such a consensus in the industry,Silicon carbide is the key to open the door to the 800V platform of electric vehicles.
The so-called 800V voltage platform has been mass-produced on the Porsche Taycan as early as 2019. However, the 800V platform on the Taycan did not fully use SiC devices at that time, and silicon-based IGBTs were still used in power modules.
After the Porsche Taycan, more and more car companies announced to join the army of high-voltage platforms, including Geely’s SEA vast architecture, BYD e platform 3.0, general UItium platform, and two days ago, Xiaopeng Automobile announced that it will launch“China’s first 800V high-voltage mass production platform equipped with silicon carbide chips”.
Take Xiaopeng as an example. Under the 800V high-voltage platform, the peak charging current is greater than 600A, and the maximum efficiency of the electric drive will be greater than 95%, that is, 200km of battery life can be achieved after 5 minutes of charging. The flow capacity of the supporting 480kW high-pressure super-filled pile can reach more than 670A.
When car companies talk about 800V high-voltage platforms, without exception, they will mention silicon carbide. In fact, silicon carbide materials are almost born for 800V high-voltage platforms at the moment. Compared with silicon materials, silicon carbide mainly has the advantages of high pressure resistance, high temperature resistance and high frequency in terms of material characteristics.
You know, for 800V and above high-voltage platforms, the motor inverter is one of the most critical components. However, the current inverters in the 400V platform basically use silicon-based IGBTs as the core. As the voltage increases, the overall efficiency of the silicon carbide devices is improved more obviously.
For inverters, the use of silicon carbide MOSFETs under the 800V high-voltage platform will increase the overall system efficiency by 8% compared to traditional silicon-based IGBTs. At the same time, under the same power premise, the size and weight of the module using SiC devices are greatly reduced compared to traditional silicon-based modules, and even the switching loss can be reduced by 75%. This can be said to be a rigid demand for electric vehicles with great demands for lightweight and energy saving.
If we say that the power battery solves the problem of energy storage. That silicon carbide solves the most fundamental energy efficiency problem: more efficient power conversion efficiency means higher cruising range and higher charging efficiency.
However, the problem for Weilai is coming. Although the silicon carbide power module is applied to the motor on the ET7, why is it still the more mature 400V platform now?
“Nio’s existing platforms are all based on a 400V architecture, which are mainly matched with the whole vehicle and battery. At this stage, only 400V is enough for NIO’s platforms. For the 800V platform, NIO’s electric drive and battery industrialization are sufficient. Senior vice president Zeng Shuxiang replied: “If you can’t get 800V in the later stage, please watch the press conference. There will be more and more new products in the future. We are stocking this area of technology. There is no doubt about this. “
According to Zeng Shuxiang, since 2015, NIO has invested a total of 250 million yuan in R&D in the XPT Electric Drive System Advanced Manufacturing Center (excluding R&D salary and site costs), including test outsourcing related to model matching and development verification. About 130 million yuan, about 96 million yuan for test bench equipment, and nearly 30 million yuan for various software tools.
In contrast, BYD established its own R&D team in 2005 and invested heavily in the IGBT industry. According to the financial report, BYD Semiconductor has invested 110 million yuan, 97 million yuan and 136 million yuan in R&D in 2018, 2019, and 2020, accounting for 8.2%, 8.87%, and 9.42% of revenue, respectively. At present, BYD Semiconductor is the only company in China that realizes mass-loading of silicon carbide three-phase full-bridge modules in new energy vehicle motor drive controllers.
Write at the end
New technologies often have both advantages and disadvantages.
Wen Xuhui, Director of the Research Department of the Institute of Electrical Engineering of the Chinese Academy of Sciences, pointed out, “Although the power density of automotive silicon carbide controllers has been greatly increased and the loss has been significantly reduced, the electromagnetic interference problems caused by fast switching are also prominent. Therefore, wide-band electromagnetic interference prediction and high-density electromagnetic interference Interference filtering is one of the focus of future industry research.”
Another issue is productivity. Forecast data shows that after all the devices used on the Tesla Model 3 are replaced with SiC, an average of 2 cars will need to consume a 6-inch SiC wafer.
And if Tesla can reach the goal of delivering 1 million vehicles in 2022, then Tesla alone will consume 500,000 SiC wafers. You know, the current global annual production capacity of SiC wafers is only about 400,000 to 600,000 pieces, which means that a car company will consume all the current global SiC wafer production capacity, which is obviously unreasonable.
Of course, whether it is a solid-state battery in battery technology or a silicon carbide power module in a drive motor, the introduction of new technology will inevitably require someone to dare to eat crabs and solve problems in order to achieve larger-scale mass production. In the end, under the effect of scale, costs continue to drop, and performance and efficiency continue to increase.
So, who will be the first to eat a crab for the mass production of silicon carbide +800V platform?