Research On High Response Servo Control Of Permanent Magnet Synchronous Motor

AC servo system has been widely used in the field of industrial control.However,in the case of higher requirements for AC servo systems,the general servo system cannot meet the performance requirements.For this reason,the performance of the AC servo system needs to be further improved.AC servo system usually has three performance indicators: high accuracy,high response and strong immunity.This paper mainly focuses on the high response of the AC servo system.First,analyze the three-loop(current loop,speed loop and position loop)control structure of the AC servo system for analysis.By establishing a mathematical model of the system,analyzing the relationship between the system energy and the adjustment parameters,and designing reasonable parameters to achieve better system performance control.Because the main link that affects the response of the AC servo system is the current loop,a detailed analysis of the current loop is performed to build the current loop model and its transfer function.The main delay part in the current loop is the current sampling part.The PWM double refresh method shortens the current sampling delay and improves the system response.At the same time,a current prediction algorithm is designed for the current sampling delay.The current sampled is predicted and calculated to obtain the predicted current for the next cycle and sent to the system.In this way,the sampling time is reduced and the system bandwidth is increased.Because the current prediction algorithm is more sensitive to the motor parameters,an observer is constructed to observe the motor parameters in real time and feed the observations back to the current prediction algorithm to ensure accurate prediction results.Secondly,analyze the anti-disturbance capability of the AC servo system.In order to make the system quickly adjust to return to normal operation when it is disturbed by the outside world,a load torque observer is constructed to observe the load torque of the motor in real time.When a sudden change occurs,compensating the q-axis current through the torque observer can make the system quickly adjust and restore normal operation;at the same time,simultaneously identify the moment of inertia of the motor on-line that affects the observation results to achieve the observer works fine.when the moment of inertia changes.Finally,because the AC servo system usually operates with a load,when themechanism connected to the load is not rigid(flexible link),the system will resonate at high gain.In order to weaken the resonance of the system,this article uses a notch filter to suppress the amplitude of the resonance frequency point;however,the addition of a notch filter will cause the system to lag in phase,resulting in a slower system response.The refactoring method ensures that the system can respond quickly without generating vibration under the flexible connection device.Matlab/Simulink simulation and field experiments show the effectiveness of the above control method in AC servo system.