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Intelligent and Safe New Energy Vehicle Potential Core Chip
New energy vehicles have the advantages of intelligence, safety, and energy saving, and therefore have become the most promising automotive intelligent technology in the past three years. According to the "Technical Roadmap for Electric Vehicles (EV) and Plug-in Electric Vehicles (PHEV)" released by the International Energy Agency (IEA) in 2011, the new energy vehicle market will enter a period of rapid development, with market share expanding rapidly.In order to reduce air pollution, China is actively promoting the development of new energy vehicles. Many cities such as Beijing have launched preferential subsidies for electric vehicles. The new energy vehicle market has huge potential. In this context, intelligent and safe new energy vehicles have become the focus of development.
Intelligent and safe new energy vehicles can be considered from the following aspects. First, body control. Drivers are more concerned about driving experience, such as ride comfort. The representative is the magic body control system. The front camera will automatically scan the road conditions 15 meters ahead, and intelligently adjust the soft and hard height of the suspension to provide the best ride comfort; the second is active safety. Active safety technology can improve driving safety. , and typical active safety systems include blind spot detection, lane departure warning, adaptive cruise, parking assist, etc.; the third is gesture control. The purpose of controlling the car can be achieved through gestures, of which Google's gesture control patent is the representative technology; the fourth is intelligent power management. The electric energy of pure electric, hybrid and other electric vehicles needs to be efficiently managed, more secure and reliable energy supply, and to reduce energy loss and increase service life; fifthly, advanced tire pressure monitoring. Tire pressure is very important to driving safety and vehicle fuel economy, and the tire pressure monitoring system is responsible for detecting tire pressure. Future tire pressure sensors should not only be able to detect tire pressure, but also have more functions, such as detecting tire tread depth.
The application of new energy vehicles is accelerating, safety is the foundation, intelligence is the trend, and core chip research and development is the key technology. Currently, core chips mainly include battery management chips (BMS), tire pressure monitoring chips (TPMS) and body control chips (BCM).
The battery management system (BMS) is the link between the battery and the user. It can accurately monitor the voltage, current and temperature information of the battery pack in real time, estimate the battery status, and has abnormal alarm, balance control, thermal management and other functions to ensure efficient and safe use of the battery. The occurrence of multiple spontaneous combustion accidents of electric vehicles has increasingly highlighted the important role of BMS in safety. With the vigorous development of the new energy vehicle market, the demand for BMS is bound to grow rapidly, and research and development has become a hot topic.
BMS can be divided into discrete solutions and integrated solutions. Traditional discrete solutions started early abroad, and domestic companies have also launched many products; integrated solutions are based on battery management chips, which integrate collection systems, protection and early warning functions. The advantages of battery management chips are that it can improve integration, improve detection accuracy and speed, high reliability, reduce system area and power consumption, and simplify system design. The disadvantages are that detection accuracy needs to be further improved, most chips cannot directly estimate battery status, and core battery management chips are basically monopolized by foreign countries. Foreign companies have launched battery management chips such as Linear's LTC6802, TI's BQ series and ADI's AD7280.
Currently, sensing BMS chips face many challenges during research and development. First of all, from the perspective of high-precision and rapid synchronous detection of series battery voltages, the voltage change during the flat period of the lithium iron phosphate battery voltage curve is small, and the voltage detection accuracy needs to be about 1mV. The operating current of power batteries is highly dynamic, and the parameters and status of hundreds of battery cells must be detected at the same time. Complete all battery cell testing as soon as possible to ensure real-time performance. Secondly, from the perspective of battery state estimation algorithm research and perception integration, monitoring battery state requires knowing the battery state that can represent battery capacity, aging and other information, such as battery state of charge (SOC), battery health state (SOH) of Health). On the one hand, it is necessary to establish an accurate battery model and improve the accuracy of battery state estimation. Based on the dual Kalman filter method, SOC and SOH are jointly estimated to improve accuracy; on the other hand, the battery state estimation algorithm is integrated on-chip. Software and hardware co-design takes into account chip computing power, power consumption, area, etc. Thirdly, from the perspective of the on-chip battery active balancing design, there are problems of battery cell inconsistency, active balancing and passive balancing. Battery balancing requires low loss, fast and accurate. The perceptual BMS chip is an intelligent balancing current distribution strategy based on battery status to improve balancing efficiency. Finally, from the perspective of high chip reliability design requirements, automotive chips have higher ESD protection requirements. According to JEDEC 22-A114D, the ESD discharge voltage for consumer electronic chips is generally 2000V; according to AEC-Q100-002-REV-D, the ESD discharge voltage for automotive chips is up to 8000V.
Currently, the Institute of Microelectronics of Tsinghua University is developing a BMS-specific sensing battery management chip, which will collect battery parameters and estimate battery status. The chip can realize the following functions, high-precision battery parameter collection, and detection accuracy reaching the international advanced level; battery state estimation algorithm on-chip to realize perception integration; intelligent battery active balancing design integrated on-chip; abnormality warning, safety management, etc. The sensing BMS chip will use the automotive electronics technology of Shanghai Advanced Semiconductor Manufacturing Co., Ltd.
In the research and development process, the first step was to realize the BMS discrete system design. Build a BMS discrete component system to realize basic functions; use microcontroller-based hardware circuits to complete basic voltage, current and temperature acquisition functions; and design battery voltage detection accuracy. The second step is to realize the design of the first-generation battery management chip. Off-chip state estimation algorithm; high-precision ADC and reference source design; automotive power system level high reliability design; battery state estimation algorithm research. The third step is to implement the second-generation battery management chip design.
For the automobile tire pressure monitoring system TPMS, Tsinghua University has launched a four-step process of TPMS research and development. The first is to replace the imported Infineon SP30 chip (with battery); the second is to replace the imported Infineon SP37 chip (with battery); the third is to independently design international Leading battery-less TPMS; fourth is advanced tire pressure monitoring.
The core technology of the advanced tire pressure monitoring system is battery-less direct tire pressure monitoring technology. This system has richer functions and can be integrated with the vehicle communication system to realize tire intelligence. First, accurately measure tire pressure and temperature data in real time; second, measure tread depth, tire load, grip and other data to provide information on the current degree of deformation of the tire; third, the data is sent to Main control unit, the main control unit calculates the remaining life of the tire. Reminder that tires can be replaced when necessary.
Advanced tire pressure monitoring is inseparable from vehicle communication systems, which are one of the main components of the Internet of Vehicles. Advanced tire pressure monitoring relies on vehicle communication systems and the Internet of Vehicles, and closely integrates the tire pressure monitoring information system with the Internet of Vehicles, opening up new prospects.
The tire inflation system is integrated with a smartphone. The main control unit of the advanced tire pressure monitoring system will be connected to the smartphone wirelessly; through the tire inflation assist system, precise tire pressure control is achieved, which is not affected by the inflator pump at the inflation station being unable to accurately measure the tire pressure; appropriate tire pressure is not only It can reduce rolling resistance, reduce fuel consumption, extend tire life, and improve driving comfort and safety.
Based on a safe and reliable 32-bit embedded CPU core, the body control chip and development platform were developed and passed the reliability assessment; based on this chip, the software and hardware co-design of body controllers and gateway controllers and embedded software adaptation technology research and development were carried out. Prototype product development; the product has passed electrical bench testing, vehicle integration verification, and road test verification of the vehicle joint unit, and has been implemented in core models of domestic independent brands such as BAIC B40, B80, C30, C50 and SAIC AP13, AS21, etc. The number of supporting packages reaches 100,000 sets.
