At present, the development of new energy vehicles around the world is in the ascendant, and China is an important market with great development potential. According to statistics, from 2011 to 2016, the annual output of electric vehicles in China has grown from less than 5,000 vehicles to 510,000 vehicles, and the number of vehicles has increased from 10,000 to 1 million vehicles, accounting for 50% of the world's total. In 2018, China's new energy vehicle production reached 1.27 million units, and continued to maintain a substantial growth momentum.
Last week, at the China International New Energy Vehicle Power Semiconductor Key Technology Forum (PSIC 2019) held in Beijing, more than 20 well-known experts, scholars and corporate leaders from home and abroad delivered keynote speeches on hot topics of concern to the industry. Zhao Huichao, director of the Institute of Electrical and Electric Drives, New Energy Development Institute, China First Automobile Co., Ltd., Wen Xuhui, researcher of the Institute of Electrical Engineering, Chinese Academy of Sciences, foreign academician of the Chinese Academy of Engineering, academician of the National Academy of Engineering, Wang Zhengping, and president of MACMIC, Zhao Shanlu, respectively In-depth analysis and discussion on the development trend of energy automobile industry, environmental reliability test evaluation technology of motor inverter IGBT power module, research and development of motor drive controller for high power density SiC vehicle, and the status quo and development of power semiconductor devices for electric vehicles .
According to Zhao Shanyu, president of Hongwei Technology, in the global electric vehicle power semiconductor market, the power semiconductor devices consumed in the power control unit have the most value, and the light-mix electric vehicle has the fastest development speed, as shown in the following figure.
In terms of power modules, the proportion of semiconductor power modules for electric vehicles to the total number of modules will increase in the next five years. In 2017, the market size will be 3.4 billion US dollars, and Yole expects to reach 5.2 billion US dollars in 2023, compared with 2017. Increase by 50%.
Automotive IGBT
At present, new energy vehicles have entered a rapid development track, and their development has gradually shifted from policy-oriented to market-oriented. On this basis, key components of new energy vehicles have entered a period of full competition, ensuring quality and reducing costs are important issues.
Director Zhao Huichao from China FAW said that the vehicle power module (currently the mainstream is IGBT) determines the key performance of the vehicle electric drive system, and accounts for more than 40% of the cost of the motor inverter. It is the core component.
According to Zhao Shanzhen, IGBTs account for about one-third of the cost of motor drives, while motor drives account for about 15-20% of the cost of a complete vehicle. That is, IGBTs account for 5 to 7% of the cost of a complete vehicle. In 2018, if China's new energy vehicle sales are calculated at 1.25 million units, an average of about $450 IGBTs per vehicle will be consumed. All vehicles will consume about 560 million US dollars of IGBTs.
Regarding the failure analysis, Zhao Huichao said that the IGBT module is made of laminated materials and materials of different materials, through welding, sintering, eutectic bonding and other processes. The mechanical strength and expansion coefficient of each layer of material are different, and the tensile strength, tear resistance and fatigue resistance are also different. These are the main factors affecting IGBT failure.
Unified quality assessment standards and full competition are urgent needs of the current automotive industry for power module products. The evaluation of IGBT is the most important, involving specific assessment requirements, can be divided into three types of tests, namely: electrical rating / peak test of IGBT modules, electrothermal characteristics test, and environmental and reliability tests.
When talking about the development trend of IGBT, Zhao Shanlu said that at the technical level, IGBT chips have undergone a series of iterative processes, including upgrading from PT to NPT to FS, which thin the chip and reduce the thermal resistance. Improved Tj; the introduction of IEGT, CSTBT and MPT continues to reduce Vce and increase power density; Optimized by surface metal and passivation layer to meet the high reliability requirements of automotive.
In addition to the technical aspects, IGBTs are also innovative in their structure, such as the emergence of RC-IGBTs and the integration of FWD and IGBTs. In addition, there are also integrated functions such as integrated current and temperature sensors.
Development of automotive SiC devices
In today's power semiconductor field, SiC devices are gaining more and more attention, and power semiconductors for vehicles are no exception. So why is the market so SiC so favored? In this regard, Zhao Shanzhen concluded: 1. The working junction temperature of SiC devices is above 200 °C, the operating frequency is above 100 kHz, and the withstand voltage is up to 20 kV. These properties are superior to traditional silicon devices; 2. The volume of SiC devices can be reduced to 1/3~1/5 of IGBT machine can reduce weight to 40~60%; 3. SiC device can also improve system efficiency and further improve cost performance and reliability.
Under the different working conditions of electric vehicles, the performance comparison between SiC devices and IGBTs is shown in the figure below. Under different working conditions, the power consumption of SiC is reduced by 60~80%, and the efficiency is improved by 1~3%.
Therefore, the efficiency increase makes the electric vehicle's endurance increased by 10%, the size of the PCU is reduced to 1/5, and more importantly, the system cost is significantly lower than that of the IGBT.
At present, the mainstream suppliers of SiC MOSFETs worldwide include Cree, Rohm and Infineon. From the horizontal comparison of SiC MOSFETs of the three representative manufacturers in Europe and America, the technical capabilities of their cell structure are different. Their product development trends tend to be higher voltages, higher currents, or higher current densities.
Of course, there are advantages and disadvantages. Zhao Shanzhen believes that the current challenges of SiC chips mainly include: 1. Low yield and high cost; 2. There are many interface defects in SiC and SiO 2 , and long-term reliability of gate oxide is a problem; MOSFETs lack long-term reliability data.
When it comes to the development of SiC devices, especially the problems with SiC hybrid switch modules, Ms. Wen Xuhui, a researcher at the Institute of Electrical Engineering of the Chinese Academy of Sciences, said that at present, the current carrying capacity of SiC chips is low, and the cost is too high. The cost of the same level of SiC MOSFET chips is 8 to 12 times that of silicon-based IGBTs. In terms of power consumption, the SiC MOSFET is turned on before the silicon-based IGBT, and then turned off in the IGBT, and the IGBT can realize ZVS (zero voltage switching), which can greatly reduce the loss.
Therefore, overall, the electrical characteristics of silicon-based IGBTs are close to 90% of SiC MOSFET chips, and the cost is 25% of SiC MOSFETs.
Wen Xuhui said that when the SiC hybrid switch module gate drive development is carried out, there is a problem that the IGBT chip malfunctions when the SiC chip is turned off at high speed, and the solution to this problem is as follows: 1. Using the Miller clamp function Drive the chip; 2. Optimize the gate drive PCB to reduce the stray impedance of the relevant path.
In summary, Wen Xuhui believes that because silicon is cheap and easy to use, SiC and silicon hybrid switch modules will have great market application prospects, and pure SiC chips and devices will take time to become popular in automotive power systems.
In addition, Dr. Ding Jiapei from ASM, Yang Jiye from Huahong Hongli Technical Director, Lu Fei from Heraeus Marketing Manager, Gu Yueji, Senior Development Manager of Silan Micro, Cai Xiongfei, Director of Basic Semiconductor Marketing, Helge Lehmman, KruS Application Manager, Chen Lanlan, Friends Strong International Technical Director Zhou Dan, SAIC Infineon General Manager Wang Xuehe, Tsinghua University Professor Li Yongdong, United Electronics R&D Director Sun Hui, ZF R&D Center Expert Liang Xiaoguang, Tyco Tianrun Technical Director Li Zhijun, Origin China Marketing Manager Ma Qing Lu Haifeng, an associate professor at Tsinghua University, and Wang Laili, a professor at Xi'an Jiaotong University, gave special reports on the hot issues in all aspects of the industry chain. In the communication session, the participants held a heated discussion about the development trend of the new energy automobile industry, the research and development of IGBT core technology, and key production processes.
In the exhibition exhibition of the same period of the forum, Silan Micro, Heraeus, Orubis, ASM, Youqiang International, Fu Shide as the gold sponsors and on-site display of the latest technology products, SAIC Infineon, Hongwei Major enterprises in 49 industrial chains, such as science and technology, basic semiconductors, Weiguang Technology, Tianlijing, Zhonghao Weilai, Tianyang Electronics, Jingjing, and Lixin Taisite, have demonstrated the most advanced products and technologies.
PSIC 2019
PSIC 2019 is provided by China Power Electronics Industry Network, Beijing Power Electronics Society, China Electrical Equipment Industry Association Power Electronics Branch, Automotive Electronic Components Standard Working Committee, China Electrical Technology Society Electrical Energy Conservation Committee, China Power Supply Society Component Special Committee, China New Energy Vehicle Power Semiconductor Key Technology and Industry Alliance, China Power Device Packaging and Testing Equipment and Materials Industry Alliance, National Key Laboratory of Wide Band-Gap Semiconductor Power Electronics, co-sponsored by Beijing Qingquan Consulting Services Co., Ltd.
