The use of electronic control units in automobiles is increasing, and data communication between electronic devices is becoming more and more. At the same time, the large-scale use of these separate modules increases the comfort of the vehicle and increases the cost and failure. The rate is rising, the wiring is complicated, and so on. Therefore, it is necessary to design a powerful control module to realize these discrete controller functions and control a large number of electrical appliances. This is BCM (B ODY CONTROL MODEL). At present, BCM is also a hot topic in automotive electronics research, and the competition is fierce.
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The research and application of BCM has greatly improved the performance of the whole vehicle. However, with the further development of automotive electronics technology, the functions of BCM integration are also increasing. The design of BCM has become more and more complicated. The centralized control also causes the wiring harness to be too concentrated, and the installation and wiring are also complicated.
BCM has the following development trend: more and more body electronics are applied in the body, which makes the BCM control more objects; the functions of each electronic device are more and more, and various functions need to be realized by BCM, which makes the BCM function more Powerful; more and more information sharing between electronic devices, one information can be used for many components at the same time, requiring BCM data communication functions to become stronger and stronger; a single centralized BCM is difficult to complete more and more functions, making Bus-based, networked BCM has become a development trend. The CAN bus is a serial multi-master controller LAN bus, which is a serial communication network that effectively supports distributed control or real-time control. Because of its high communication speed, good reliability and low price, it is especially suitable for automotive systems. Therefore, it is an inevitable trend of BCM development to control the body electrical and electronic devices by using CAN bus technology.
Bus-type body control system becomes an inevitable trend of BCM development
Based on the low-speed CAN bus, LIN and other automotive electronic network systems, the bus body control system has become an inevitable trend in the development of BCM. The following describes the bus type BCM in detail with the research conducted by Shanghai Tongde Electronic Engineering Technology Co., Ltd. on the bus type BCM.
The system has two buses, low speed CAN and LIN bus.
Low-speed CAN, information transmission rate is 100 Kbps, the control object of body system CAN is mainly low-speed motor, solenoid valve, lamp and switching device, etc. They have low requirements for real-time information transmission, but the number is large; low-speed CAN bus is adopted. It can also increase the transmission distance of the bus, improve the anti-interference ability, and reduce the hardware cost. LIN bus, information transmission rate is less than 20 Kbps, LIN bus is mainly used in low-speed systems that do not require CAN performance, bandwidth and complexity, such as switch-type load or position-based system control. Therefore, LIN is more conducive to the realization of the bus-type control system of the car and CAN network connection. The main front control module, main control module and rear control module are connected to the low-speed CAN bus; the main control module, the door control module, the central control lock module, the voice alarm module, etc. communicate through the LIN bus.
The system has the following advantages:
First of all, after adopting this mode, the system is very simple, the wiring harness is also very simple, the wiring is convenient, and the advantage of the bus is fully exerted.
Secondly, the function of BCM is shared by a small number of modules, and each module can have a very strong function:
1. For large inductive loads, such as wipers, blowers, fans, etc., in order to reduce the impact on the system power supply, while protecting the electrical equipment, the soft start can be implemented by PWM;
2. Short-circuit protection for electrical equipment. When a short-circuit fault occurs, cut off the power supply circuit in time to avoid accidents such as fire on the line;
3. Implement secondary power-on for short-circuit faults to further improve the system's anti-interference ability;
4. Diagnose, fault alarm, information record, etc. of equipment failure;
5. Complex functions are coordinated by each module.
Finally, information sharing is achieved to facilitate the use and development of new devices. In this system, almost all information is transmitted on the bus according to the protocol and is broadcasted, so the vehicle information can be easily obtained by the new device. Therefore, the CAN bus-based driving recorder and fault diagnostic tool only need to read the required signals from the bus according to the protocol, which makes product development easy and low in cost.
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