SiC is the crown jewel of power semiconductors.
Text/Nguyen Kam Cheng
I remember visiting bosch booths at the Beijing Auto Show two years ago. Including a variety of electric drives, ADAS sensors, hydrogen fuel cells and other "tall" exhibits, there are too many to see.
SiC silicon carbide power devices exhibited at Bosch 2020 Beijing Auto Show
But when Bosch introduced their technology, it attached great importance to a black chip in a glass box, about the size of a finger, SiC silicon carbide power device.
In the past two years of technology product releases, "SiC silicon carbide" has become a frequently mentioned star product of all multinational parts suppliers and OEMs, including Magna, BorgWarner, MAHLE, Continental, etc., all of which have claimed that they use silicon carbide.
For example, the EQXX released by Mercedes-Benz at the beginning of this year declared: "Equipped with a rear axle motor with a maximum power of 150kW, the silicon carbide power module is applied, which further reduces the loss." ”
What is SiC Silicon Carbide? What role does it play in electric vehicles?
For example, many people now use "Gallium nitride" chargers in mobile phones, which are very small in size, but have a high efficiency in charging with small heat. The automotive SiC silicon carbide is the same magical power semiconductor as gallium nitride in consumer appliances.
BorgWarner offers a new 800V silicon carbide inverter for its own brands
First, let's talk about the role of SiC silicon carbide. When an electric car is charged, it needs to convert alternating current into direct current and store it in a lithium battery. The high-voltage DC in lithium batteries is converted into alternating current, which is then provided for AC motor use.
The above complex conversion processes such as AC-DC-AC, which we call rectification or inverter, unfortunately this process requires heating, which will produce power loss.
Components involved in power semiconductors in electric vehicles include motor drive systems, in-vehicle charging systems (OBC), power conversion systems (on-board DC/DC) and non-on-board charging piles. SiC silicon carbide power devices superimpose high voltage currents on some key main inverters (such as electric drives), SiC silicon carbide still has an absolute advantage over IGBT.
The powerful properties of SiC silicon carbide are due to the tiny carbon atoms. SiC silicon carbide enables raw materials to support higher switching frequencies.
Magna EtelligentReach Next-generation all-wheel electric drive
Silicon carbide semiconductors lose only half as much thermal energy as pure silicon chips, thus increasing the driving range of electric vehicles. Like the 800-volt voltage system of future electric vehicles, silicon carbide can immediately speed up charging speed and improve product performance. It also saves the cooling cost of power electronic equipment and reduces the weight of electric vehicles themselves.
Bosch's Silicon Carbide power devices, for example, maintain low energy losses and small chip areas compared to traditional silicon-based material products (IGBTs), increasing the cruising range of electric and hybrid vehicles by up to 6%.
Some of the most advanced electric vehicles in the domestic market have actually applied SiC silicon carbide power modules.
For example, Tesla's Model 3's main electric drive inverter uses a SiC MOSFET. Among the new models released in 2021, like the second generation of THEO ET7 electric drive, xiaopeng's G9, and great wall's mecha dragon are all using SiC silicon carbide modules. Each module consists of several SiC chip packages.
The high-performance all-wheel drive version of Han EV released by BYD in 2020 is the first model in China to adopt a self-developed SiC silicon carbide module, and the supplier is its own BYD semiconductor.
BYD Semiconductor SiC power module
BYD Semiconductor SiC wafers
BYD Semiconductor's SiC Silicon Carbide Power Module is a three-phase full-bridge topology, mainly used in new energy vehicle motor drive controllers. BYD claims to be "the world's first and only SiC three-phase full-bridge module in China to achieve large-scale loading in motor drive controllers." ”
BYD SiC power module output power can reach more than 250kW, compared with the same power level of IGBT, the module size can be reduced by more than half.
It is conceivable that in the future, cars will be electrified, so the demand for SiC silicon carbide power devices is huge. According to the forecast released by market research consulting firm Yole, the silicon carbide market will grow by 30% per year between now and 2025, and the market size will exceed 2.5 billion US dollars.
When the scale reaches $1.5 billion, cars equipped with silicon carbide devices will dominate the market.
The mass production of power semiconductors SiC silicon carbide and IGBT, concentrated in Germany's Infineon, NXP NXP, STMicroelectronics STM, ON Semi and others, especially Infineon's advantages are obvious.
At present, the domestic manufacturer that can achieve independent research and development to mass production is BYD, and its BYD semiconductor products include mainstream IGBT, as well as high-end product SiC silicon carbide MOFEST, etc., covering a very comprehensive range.
BYD Semiconductor's SiC automotive power module is very compact, only the size of a palm, and the output power is 250KW. The self-produced SiC power semiconductor also allows BYD electric vehicles to bring significant efficiency improvements in motor drive and reduce the volume of motor drive controllers by more than 60%.
Bosch is the only automotive supplier that produces silicon carbide chips in-house
It is precisely because of the importance of SiC silicon carbide that Bosch, which ranks first in automotive parts, announced two years ago that it would continue to promote the development and mass production of silicon carbide chips.
Bosch's mass production is not only a module in a SiC package, but also a mass production of the most basic wafers and chips.
Bosch Reutlingen fab
In 2021, Bosch has built an additional 1,000 square meters of dust-free workshops at the Reutlingen wafer factory, and another 3,000 square meters of dust-free workshops will be built by the end of 2023. The 150 mm wafer currently in use, and the 200 mm wafer manufacturing is soon planned, will take months for a single wafer to complete hundreds of process steps in countless machines.
Bosch will continue to expand its production capacity of silicon carbide power semiconductors and plans to increase output to hundreds of millions of units. At the same time, the development of a second-generation silicon carbide chip with higher power density is expected to be put into mass production in 2022.
In the future, to realize the dream of "corner overtaking" of our electric vehicles, we must have breakthroughs in key technologies. For electric vehicles, SiC silicon carbide power chips are the technology we need to break through the most.