Introduction of three major technologies for the development and practical application of automotive electronic systems

　　In the past few decades, the number and complexity of automotive electronic systems have increased tremendously. Due to the extensive use of electronic components, such as various sensors, microprocessors, electric drives, etc., the cost of automobiles has greatly increased. Today, electronic systems on mid-to-high-end vehicles have accounted for more than 23% of the total vehicle manufacturing costs. The average cost of electronic products on a car rose from US$110 in 1977 to US$1,800 in 2001. Automotive experts believe that 80% of the current new technologies in automobiles come from the continuous update and progress of electronic systems. It is estimated that in the next ten years, the proportion of automotive electronics and electronic technology-related products in the total vehicle cost will rise from the current 20% to 32%. The growth rate of automotive electronics will rise from the current 10% to 20%.

　　Due to people's pursuit of energy-saving, safety, comfort, convenience and luxury of automobiles, higher requirements are put forward on the performance of automobiles. The use of traditional machinery has not been able to further significantly improve the performance of the car. In recent years, the rapid development of microelectronics technology, especially the tremendous progress of microcomputer technology, has combined electronic technology with traditional machinery, making the environmental protection, energy saving, safety, comfort, convenience, and intelligence of automobiles all available. Get a good solution.

　　The author believes that the current and practical automotive electronics technologies are mainly concentrated in three areas, namely the following three technologies:

　　(1) The development and use of electronic control technology, namely electronic control or X-by-wire technology;

　　(2) The continuous use and popularization of vehicle network systems, especially CAN networks;

　　(3) The new voltage system 42V (volt) to be adopted for the whole vehicle electrical system.

　　The development of these three technologies, some have already begun to be practical, and some are about to be put into practical use. For this reason, when our country introduces new models with these new technologies, it also needs to be familiar with and research on these technologies. Only in this way can we improve our car design and manufacturing level, so that our car manufacturers can reach it as soon as possible. International level.

　　2X-by-wire technology

　　In the past, automobiles used to be the world of mechanical and hydraulic systems. With the continuous improvement of people's requirements for automobiles, especially the requirements for emissions and safety, today's automobiles have become a highly mechatronics automatic system. With the development of technology, this trend becomes more and more obvious.

　　People now often mention a noun "X-by-wire", "wire" means wire, "by-wire" can be understood as an electronic control method, and the "X" here is like an unknown number in a mathematical equation, representing The various components in the car that are traditionally controlled by mechanical or hydraulic pressure, such as the engine, suspension, steering gear, etc., are large, and the small ones are throttle, door locks, etc. Obviously, in order to meet people's higher requirements for automobiles, these mechanical or hydraulically controlled components are gradually being transformed into electromechanical and hydraulic integrated control, or even into a purely electronic control method.

　　At present, the work of replacing mechanical components with reasonably configured electronic components is proceeding in an orderly manner, and the performance and level of the system have also been continuously improved. The cost of advanced electronic systems is also plummeting. Complicated high-performance electronic components such as chassis control and sensitive sensing have been applied to high-end cars and gradually become the mainstream.

　　The highly reliable fault-tolerant electronic control system X-by-wire does not rely on traditional mechanical and hydraulic devices. It makes the car lighter, cheaper, safer and more fuel-efficient. Its self-diagnostic system and adaptation system are suitable for all types of vehicles. This system can eliminate the car's drive belt, hydraulic brake pump, and even the steering column, resulting in a car without a steering wheel.

　　In fact, by 2010, one-third of new cars will have electronic driving systems. The X-by-wire driving system under development will replace the steering column with an angle sensor and feedback motor. A serial network provides control links to the executive motors mounted on the wheels. This change in the steering column will improve the safety of the driver in the event of a collision. It will simplify left and right hand driving parts.

　　On the basis of this electronic system, it is very easy to add some advanced functions. For example, in the mechanical steering system, the driver cannot use the steering wheel correctly at high speed (for example, due to panic, steering too fast), and the electronic control method can drive the executive motor within an appropriate range to skip this out-of-control phase.

　　All major automakers are developing the prototype of the X-by-wire system and its products. For example, the TRW electronic driving assistance system has increased fuel economy by 5%. Delphi Automobiles claims to have made similar improvements in E-steersystem. Bosch, Valeo and other equipment manufacturers have developed or are developing X-by-wire technology and products.

　　3 car network

　　With the development of automotive electronic technology, many electronic control units have appeared in automobiles, such as engine control modules (ECM), BVA computers, smart displays, ABS, etc. There is a large amount of information exchange between these electronic components with microprocessors. In the past, wires were used as the standard connection method for electrical components. However, with the continuous increase of electronic products, more and more connection lines have become barriers to technological development.

　　Using the traditional wiring harness solution will greatly increase the length and number of connections, while the ever-increasing wiring harness and increasing number of connectors increase the quality of the car, weaken the performance, and make it difficult to guarantee reliability. For a normal driving vehicle, every time the wiring harness exceeds 50g or the energy loss exceeds 100W, the fuel consumption per 100 kilometers will increase by 0.2L. Moreover, the complicated wiring harness connector makes the voltage drop significantly, restricts the normal use of other functions, and becomes the most expensive and cumbersome part of the automotive electronic system.

　　The car network system is to connect the electrical components to the car control network, just like the computer is connected to the local area network. These networks can easily share information and resources, thus successfully solving the above technical difficulties. This is also a typical example of the successful combination of modern computer network technology and automotive electronics technology. At present, the in-vehicle network system has begun to be widely used all over the world. The most widely used network protocol standard in automobiles is the CAN (Controller Area Network) network.

　　In the mid-1980s, Bosch company developed this kind of control local area network, which is the earliest and longest used car control network. CAN network has been widely used in current automobiles. In 2000 alone, sales of related devices exceeded 100 million.

　　A typical vehicle with a CAN network can accommodate 2 to 3 independent CAN networks operating at different transmission rates at the same time. The low-speed CAN network runs at 125Kbps and is usually responsible for managing "comfort functions", such as electric seats. , Electric glass lift and so on. In general, low-speed networks are used for control without real-time requirements. It has energy storage-sleep mode, in this mode, the node stops oscillating until a CAN network message wakes it up. Sleep mode prevents power consumption.

　　High-speed CAN network is used to meet important control with high real-time performance. Such as: engine management, ABS, cruise. Although the maximum baud rate of the high-speed CAN network can reach 1Mbps, large electromagnetic radiation is generated in the twisted-pair cable during the high-speed operation of the CAN network. When the transmission rate exceeds 500kbps, the energy loss will increase rapidly. So the general high-speed network is 500kbps.

　　4 power supply and 42V solution

　　With the rapid increase of electronic systems in automobiles, they will consume a lot of electric energy, making the total load about to exceed 2kW. Internal energy demand will increase at a rate of 4% per year. If this trend continues to go down, then conservatively estimated that by 2005, the average power demand of high-end cars will reach 2.5kW. This growth will make the current power supply system appear to be inadequate. For example: under a load of 3kW, a generator with a bracket and a belt drive will emit obvious noise, and additional cooling devices are required.

　　In an automotive electronic system, for a specific power, the increase in the voltage value can reduce the system current. The small current can reduce the loss on the wire, so that a thinner and smaller wire harness can be used. Increasing the voltage value can also reduce the volume, quality and loss of the electrical device itself, and it is also conducive to the miniaturization of the control device and the improvement of the integration.

　　The 42V electrical system needs a 36V battery, the maximum working voltage is 50V, and the peak voltage can reach 58V. This is because 60V is the maximum safety limit that engineers think. Higher voltage will cause harm.

　　Although the advantages of the 42V system are obvious, the conversion from a 12V system that has been in use for half a century to a 42V system requires a great deal of redesign and manufacturing of products, and maintenance and upgrades will bring obstacles. Therefore, it is currently more realistic to adopt a 14V/42V dual-voltage solution to reduce the impact on the auto parts manufacturing industry and achieve a smooth transition.

　　The conversion process of 　　14V/42V dual voltage is as follows: the alternator outputs a high voltage of 42V, and with the help of a DC/DC converter (direct current converter), 42V is converted to 14V. In this system, the DC/DC converter divides the power supply system into two power supply systems with different voltage levels. In addition to step-down, it also plays an important role in the power distribution management of the entire electrical system.