Research On AC Servo High-performance Drive And Its Network High-precision Synchronous Control

As the key executive component of high-end manufacturing processing equipment,multi-axis servo system plays an important role in the manufacturing process of key components in aerospace,marine engineering,agricultural machinery equipment and other fields.With the continuous development of high-end manufacturing and processing equipment,the demand for high dynamic response ability,high precision,strong stability and accurate synchronization of multi-axis servo systems is increasing.Therefore,both the performance optimization strategy for single-axis servo system and the clock synchronization technology of networked multi-axis servo system were researched in the dissertation,aiming to comprehensively improve its operation quality to promote the development of high-end equipment in our country.Aiming at the problem that the dynamic response of the inner current loop of the servo system can be deteriorated by the coupling characteristics of the electromechanical system,a unified current decoupling control strategy based on an interval PI sliding mode observer was proposed on the basis of comprehensively considering the current coupling and backEMF changes.By analyzing the convergence process and error source of the traditional scheme,a method for constructing the interval PI based control law for the quasi-sliding mode observer without steady-state error was provided by this strategy.The setting method and robustness of control law parameters in new strategy were also theoretically analyzed in detail.The effectiveness of the decoupling control scheme was verified by experiment.Aiming at the problem that the torque control performance of the servo system is restricted by the loop delay,a current control strategy based on oversampling was proposed.The oversampling range was shortened to half the Pulse Width Modulation(PWM)period novelly.The internal model control method was adopted for designing a new controller structure,Space Vector Pulse Width Modulation(SVPWM)output method was modified to maintain the noise immunity and a set of parameters for balanced tracking and antidisturbance performance was also optimized relying on designing cost function.The characteristics of high precision,high dynamic response and strong anti-disturbance with proposed current control strategy were showed through experimental verification.Aiming at the mechanical resonance often caused by high gain outer loop of the servo system,a resonance suppression scheme based on fast tracking adaptive notch filter was proposed by analyzing the root causes of the oscillation frequency deviation in the highbandwidth system.Multiple cycles of oscillation frequency detection and notch filter reconstruction were used to eliminate the deviation.At the same time,based on the range Shift Discrete Fourier Transformation(SDFT)oscillation frequency detection method,a reasonable detection interval and prediction strategy were adopted to effectively improve the detection speed and further shorten the oscillation suppression time.The mechanical resonance was suppressed quickly and effectively by this scheme in experiments.On the basis of realizing single-axis servo drives with high precision and high dynamic response,aiming at the difficult synchronization of all devices in the networked multi-axis servo system,a complete scheme for precisely synchronizating both master and slave devices in network,and network and local control tasks was proposed by promoting the concept of time control loop in the Ether CAT standard protocol.This scheme not only achieved accurate clock synchronization between the master and the reference slave in the normal mode,adjusted the timing of local control tasks to ensure the simplicity and certainty of the software.But also utilized the synchronized master to maintain synchronization of the slaves in the redundant loop when operating in the redundancy mode.The clock synchronization accuracy of all devices in the network was less than 1 μs in experiments.The research results of the dissertation have been successfully transplanted to the commercial AC servo platform.The application results showed that the proposed strategies can significantly improve the control performances of the AC servo system and have high theoretical and practical value.