Research On Key Techniques’ Of High-power High-precision Permanent Magnet AC Servo System

The permanent magnet synchronous motor(PMSM) is used for more and more low power fields by its High precision, high power factor, high response and high efficiency, such as aerospace, military industry, textile machinery and so on. In recent years, it is gradually replacing the asynchronous motor, and widely used in high power applications. In large-scale high-end equipment applications, there are two key technologies because of the load’s big change and the complex application environments. The one is how to build the high reliability of high-power permanent magnet ac servo system hardware. The other one is how to restrain the ill effects of the change of the load. This paper mainly revolves around these two keys.First, the principle of sliding mode variable structure control and the mathematical model of permanent magnet synchronous motor were analyzed in consideration of load disturbance rejection algorithm’s research perspective. The mathematical model of the traditional sliding mode observer of load torque identification was built on this basis. In order to prevent the impact of the chattering of sliding mode variable structure control, feedback gain was introduced, control function was optimized, low pass filter was improved. The new sliding mode observer of load torque identification was built based on these improvements. Then, its stability analysis and digital implementation were made.Second, in order to verify the correctness of the algorithm, system principle block diagram was set up according to the principle of vector control system. The model based on Simulink by matlab of system simulation was built based on the mathematical model of the system. On this basis, the system was made several aspects of simulation test of load torque observation. At last, the new method cans really effective restrain the chattering of the load torque by comparing the new method and traditional method’s simulation result.Then, with the aim of high reliability and high precision of the circuit characteristics, the hardware of system was designed by using the TMS320F28335 as the control center. The principle of partial function circuit is analyzed emphatically, such as high precision current and position detection circuit, high reliability protection circuit, PWM isolated driver, the flyback type DC- DC power supply and so on several key points. On account of the importance of the circuit security, the protection circuit simulated by the Multisim. The results showed that it can protect the circuit very well.At last, in order to prove the feasibility and superiority of theory, an experimental test was conducted. First, on the circuit basis, the software of the new control strategy was designed, and experimental platform was constructed. Second, the system was tested by three aspects about speed control performance, load disturbance resistance performance and position control experiment performance. Then, in the process of experiment, the data acquisition card was used to collect signals, such as position, speed and so on. These data were displayed through test interface which written by Labview. The results proved that the new method can effectively restrain speed fluctuation of the load disturbance, it also testified the feasibility of the improved scheme and the scientificity of theory.