Application of the hottest fieldbus control system

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Application of fieldbus control system in traction motor test-bed 1 introduction at present, the motor test-bed of most railway plants and sections in China mainly adopts manual operation control test and manual meter reading to record test data; The degree of automation is relatively low. This manual test has obvious defects: low efficiency, high labor intensity, low test accuracy, and the reliability of test data is often affected by human factors. With the improvement of traction motor test requirements, the existing manual control of the test bench can no longer meet the requirements, and there is an urgent need to realize automatic control and computer management. The main difficulties in realizing the automatic control of the traction motor test-bed are: (1) the motor test process is complex, the steps are numerous, and the logical relationship induction is difficult; (2) The test state of traction motor is variable, and the control parameters are different under different test states, so it is difficult to achieve the ideal control effect; (3) Traction motor and test power supply are high-voltage and high current equipment, with strong electromagnetic interference and large mechanical vibration, which requires high anti-interference and reliability of control equipment. Based on this situation, we designed and adopted the motor test-bed automatic test system based on the fieldbus control system SHCAN2000, which solves the above problems and can automatically complete all inspection tests of the traction motor. The automatic control and completion of the test process are realized; Automatic collection and recording of test data; Safety alarm, automatic protection and historical record; Automatic generation and management of test reports. 2 system architecture 2.1 traction motor test bench line test bench line is shown in Figure 1. Among them, the combination of test line switches (about 30) determines different test items and different test methods. During the test, if you want to control the action of the switch according to different test items and different steps. The test has accumulated about 500 steps, and the corresponding switch combination also has 500 states. Circuit machine and booster are controllable voltage and current sources realized by silicon controlled rectifier. The dynamic output of the regulating unit of the control system is used as the setting of the line machine and booster, and the closed-loop automatic regulation output of the thyristor trigger circuit controls the working point (voltage, current, speed) of the traction motor. The magnetic chipper is a constant current source realized by IGBT. When the magnetic chipping circuit is input, it will automatically track the armature current of the tested motor and control the main magnetic pole current to maintain a fixed magnetic chipping rate. SHCAN2000 distributed control system the field price is expensive. The bus control system is a new generation of industrial automation control system with digital information, decentralized control, unified and open standards. It has the advantages of high control accuracy, strong system reliability, low cost and so on. Among them, the complete decentralization of control is the prominent feature of the ± 0.5% system of fieldbus control system. The substantive advantage it brings to users is that the functions of DCS controller are completed by highly intelligent field equipment, which weakens or even eliminates the level of centralized controller, reduces the cost of equipment and wiring, completely disperses the control risk, and improves the autonomy and reliability of system control. The structure of the control part of the system is shown in Figure 2. The SHCAN2000 distributed control system we designed and adopted adopts a three-tier architecture, that is, the operation station - can summary network (twisted pair) - field intelligent measurement and control unit. The operation station is composed of industrial PC plus card; The function of the card is to complete the protocol conversion between RS-232C and can bus, and realize the connection between industrial PC and can bus. The operation station adopts Windows2000 operating system, and the industrial control software adopts fix of American intellution company to establish a friendly man-machine interface and realize the system monitoring and management functions. The bus communication standard of SHCAN2000 system adopts CAN2.0B. The short frame structure of CAN bus, CRC verification and automatic shutdown function of error nodes ensure the reliability of signal transmission and have strong anti-interference ability. Under the strong electromagnetic interference on the site of the motor test-bed, there has never been a communication failure, which proves that the scene in front of can is showing the high reliability of bus communication every day. In the SHCAN2000 control system, the field intelligent measurement and control unit, as the core of the control system, completes all control functions; Through CAN bus, the information sharing between devices and the communication between the field and the upper computer are realized, including the transmission of control information, device status and real-time data. It is a difficult point to realize the whole control of the motor test process by the field measurement and control unit. SHCAN2000 field intelligent measurement and control unit adopts the integration technology of field intelligent measurement and control instrument software components composed of real-time multitask operating system, real-time monitoring software, task level configuration software and real-time database [2]. The download and debugging program is developed to support configuration and simulation debugging, which greatly facilitates the design and debugging of the system. 3. System function realization: the motor test bench test system can automatically complete all factory tests and some type tests of zd-106, zd-109 and qdr-410 traction motors. Next, combined with the characteristics of the test process, it is realized according to the system functions such as tube bar profile

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