First, the application of new automobile power supply is the general trend.
Today, with the rapid development of automobile technology, the capacity of automobile electrical appliances has greatly increased. In recent years, due to the difficulty in commercialization of pure battery electric vehicles, battery hybrid vehicles have emerged as clean vehicles. At the same time, with the continuous improvement of automobile intelligence, new electrical equipment has been widely used in automobiles, such as various electronic control systems (EFI, exhaust gas recirculation, pressurization, etc. ), cruise control, land navigation, real-time climate control, on-board computer network, etc. This greatly increases the proportion of automobile electronic parts. The actuators of these devices usually need large power, and the corresponding power consumption is also greatly increased. How to provide enough power to ensure the reliable operation of all electrical systems has become the bottleneck of modern automobile development.
With the improvement of people's requirements for ride comfort, fuel economy and emission environmental protection, new devices and technologies on automobiles are increasing, and energy consumption is also increasing. Because electric energy has a series of advantages such as simple transmission, easy conversion and flexible control, it has become a trend to replace hydraulic transmission and pneumatic transmission actuators with electromagnetic or electric actuators. Some charged mechanical devices are gradually transformed into electronic devices with machinery, which greatly increases the load of the electrical system. In the modern automobile with energy saving, environmental protection and safety as the center, there are more and more electrical equipment and the load of electricity consumption is increasing, which requires the automobile power supply to provide higher electric energy. The traditional 14V voltage power supply system has been stretched. Therefore, a new 42V power supply system will be applied to automobiles. 42V power supply system can provide 8KW power, which provides a great development space for automobile electrical appliances. The most important significance of adopting 42V power supply is to liberate product designers from many limitations in the past and provide enough imagination space for the development of automobile technology.
In 1980s, the generator power of domestic automobiles was generally below 500W, and now it is very common that the generator power of automobiles reaches 1000W; At that time, many cars didn't have air conditioning, but now cars without air conditioning are strange; In the past, the driver's seat of a car was manually adjusted, but now it is mostly electrically adjusted; In the past, car doors and windows were mostly manual switches, but now electric switches are popular, and so on. In the past, it was only available in high-end cars, but today it is a common configuration of modern cars. As the number of micro-motors required for automatic control on vehicles will continue to increase, the more advanced the vehicle, the more energy it consumes, resulting in the more advanced the vehicle, the greater the power it consumes. If the current voltage standard is not changed, the increase of power will inevitably lead to the increase of current, and the increase of current will inevitably increase the cross-sectional area of the conductor, in other words, the conductor will be thickened. If it continues, the main wiring harness on the car will be as thick as an arm, the volume of electrical components will become larger, the weight of the car will increase, the fuel consumption will increase, and the limited space will be occupied. Under the rated voltage of the existing electrical system, the output current of the alternator must be greatly increased to output the above high power. Low voltage and high current output will reduce the efficiency of claw-pole alternator, and in order to reduce the resistance heat loss on the line, the cross-sectional area of the conductor will increase several times, which not only increases the quality of the whole vehicle equipment, but also brings many problems to the spatial layout of engine compartment and carriage. It can be seen that the existing 14V power supply system is difficult to meet the requirements, and the only feasible way is to increase the voltage of the alternator to increase its output power. According to the existing R&D technology and production process, when the rated voltage of alternator is 14V, its output power can reach 2KW. When the rated voltage is 28V( 14×2), the output power can reach about 4KW. When the rated voltage is increased to 42V( 14×3), its output power can be increased to 6KW or even higher.
Second, the advantages of adopting 42V automobile power supply system
1, improve engine efficiency. After using the 42V power supply, the accessories driven by the engine can be separated from the engine and directly driven by the motor, which further reduces the number of engine parts, reduces the dead weight of the engine and improves the efficiency, thus avoiding the idling of accessories and improving the energy utilization efficiency.
2. Reduce the wire harness diameter. After the implementation of the 42V voltage standard, theoretically, if the voltage is increased by three times, the diameter of the wire harness can be reduced to 60% of the original (but in practice, considering the manufacturability of producing small-sized wire harness and the reliability of products, the wires should not be too thin, so the mass and volume of the wire harness for vehicles, including insulating materials and connectors, can only be reduced by 25%), which can reduce the cost, facilitate installation, use smaller body to drill holes, and improve the ride comfort of automobiles. At the same time, the transistor circuit can realize the functions of fault self-diagnosis and circuit protection with intelligent characteristics, so as to cancel the traditional fuse and make the connector smaller and lighter, so as to cancel the traditional fuse and make the connector smaller and lighter, and the switch on the car will be like the keyboard of the computer.
3. The motor and solenoid valve are very heavy, which is greatly reduced. The biggest advantage of 42V voltage system is to reduce the weight of motor and solenoid valve. Bosch experts believe that the weight of the new motor and solenoid valve can be reduced by 20% by adopting the voltage standard of 42V. The volume and weight of a simpler solenoid valve will decrease proportionally with the increase of voltage, while a smaller motor means a thinner door, more spacious seating space and even more storage space under the seat.
4. It is beneficial to the miniaturization of automobiles. In order to realize various functions, modern cars use a lot of electrical equipment, which takes up a lot of space and reduces the available space in the car. After using 42V power supply, the voltage value is increased under the same power, which can reduce the volume, mass and loss of electrical appliances and is beneficial to the installation of control coils.
5. Emancipate the design idea. Nowadays, there are more and more electrical appliances in cars. By adopting electric steering system, electric braking system, automatic navigation system, electric clutch system and automatic entertainment system, the control accuracy is improved, the safety of the whole vehicle is improved, the driving comfort and fuel economy are better, and the reliability of the automobile is also improved. Because power is proportional to the square of voltage, 42V power supply technology makes it possible for these high and new technologies to be widely used in automobiles. For the water pump and oil pump, it can be changed to electric drive, which eliminates the low-speed drag torque of the engine, achieves the purpose of reducing fuel consumption and reduces the demand for engine space. For the electrically heated three-way catalytic converter, the heating power can be increased on the original basis to further reduce the emission of cold air. The heating power can be increased on the original basis to further reduce the discharge of cold air.
6. Create conditions for the development of hybrid electric vehicles. Using 42V power supply can greatly improve the capacity of automobile power supply system and create conditions for the development of hybrid electric vehicles. This will certainly promote the development of hybrid electric vehicles, especially the development of vibration electric vehicles suitable for urban applications. In the case of urban traffic congestion, idling and ultra-low speed driving account for about 20%-30% of the total driving time of the car, which not only wastes a lot of energy, but also emits dozens of times more harmful substances than under normal working conditions. If the 42V power supply system is adopted, the motor can be directly driven by the power supply as the power source of the car at low speed, and the power supply can be conveniently cut off when waiting for the signal at the traffic control intersection, thus reducing the idle time and greatly reducing the environmental pollution of the city. The key technology is to develop the motor and related components that can complete these functions, so that it can not only start the engine, but also replace the engine as the power source. When the engine works, it can also be used as a power source, and when the engine works, it can also drive the generator to charge the power source.
In addition, the 42v power supply has some other technical advantages, such as the current ratio of 14V power supply is greatly reduced for electrical appliances with the same power, thus reducing the power loss, reducing the cross section of the conductor and saving materials. At the same time, the 42V power supply system can also supply power to other devices that need high current, such as the heating of exhaust aftertreatment devices of vehicles and other comfort devices.
The above technical measures not only do not increase the cost of the automobile, but also can improve the energy utilization rate of the automobile by more than 10% and greatly reduce the exhaust pollution of the automobile.
Third, the development trend of 42V automobile power supply system
European and American automobile manufacturers and parts suppliers have reached an agreement to raise the voltage standard of automobile power supply system from 12V to 42V, which will be implemented soon. The voltage of 12V has been used in automobiles for 30 years, which has played a certain role in improving the starting performance and improving the efficiency of electrical equipment. But it can't meet the needs of technological development at present. Theoretically, if the voltage is tripled, the current can be reduced by two-thirds, so the size and quality of cables, motors and coils can be greatly reduced. In particular, some new technologies, such as electronically controlled electric valve mechanism, integrated structure of starter and generator in flywheel, electronically controlled electric braking and steering system, can become possible. At the same time, it can reduce the quality of the car and improve the efficiency. However, increasing the voltage has an adverse effect on the filament lighting system. Therefore, coexistence with 42V can be maintained for a period of time in the initial stage.
In order to solve the growing contradiction between supply and demand of automobile power supply, General Motors of the United States has developed a power supply system suitable for 42V vehicles. EV, an electric vehicle, will first try to use this system and become the first vehicle to use 42V. It is reported that European automobile companies will take the lead in using the 42V power supply standard. It is predicted that the number of 42V vehicles will reach 46,000 in 2002 and 654.38+028,900 in 2065.438+00. It is expected that the implementation will be from easy to difficult, from small to large, that is, the dual-voltage scheme will be implemented first, then the single-voltage scheme will be implemented, and then the luxury car will be gradually implemented. It takes about 65,438+00 years to fully implement the single voltage scheme.
It is an inevitable trend for the automobile power supply system to develop from 12V(HV) power supply to 42V power supply, just like upgrading the 6V power supply to the current 12V( 14V) power supply in 1950s. As a transitional stage, there will be a 14V/42V dual voltage system. The mechanism of dual voltage power supply system may appear in the top European models in 2005 or 2006. At about the same time, some light trucks in the United States may also be equipped with these mechanisms. By 2008, about 6.5438+0.3 million European cars will adopt 42V powertrain technology.
14/42v and 42v electrical systems have been widely recognized by the international automobile industry, so it is believed that this new type of automobile electrical system will be put into practical use in the near future. Due to the inherent characteristics of the electrical system, the control device combining power semiconductor devices with microelectronic devices will be widely used in the new electrical system, which will have a great impact on the traditional automobile electrical appliances and have a far-reaching impact on the industrial structure of automobile electronics and electrical components. At present, the related industries in China have paid due attention to the new automobile electrical system, and this new automobile technology is entering the preliminary research stage.
In a word, the development of automotive materials technology must meet the development requirements of a new generation of automotive products. Automobile product designers and material workers must understand and study it to promote the development and application of products.