Design And Optimize On Current Loop Of PMSM Servo System

Permanent magnet synchronous motor(PMSM), which has clear superiorities in many aspects,such as power density, efficiency, volumn, structure and etc.,when comparing to the other motors. And it is more likely to be the main choise of precision servo systems which used in robots, machine equipments, elevators and navigation in recent years.To ensure the performances and satisfy the demands, PMSM servo system should exhibit nice dynamical response and steady state accuracy. The inner loop of servo system, current loop, is necessary to be fast and accurate to act as the basis of whole system. While the current loop contains disturbance ? delay time caused by the digital control, these would cause bring performance deterioration.A novel nonlinear controller ADRC was proposed in this paper to instead of classical PID controller. It consists of three parts: tracking differentiator(TD), nonlinear state error feedback(NLSEF) and extended state observer(ESO). By a direct compensation based on disturbance estimation and configure appropriate feedback regulation, ADRC can achieves high performance.First, the application of ADRC for current loop in the PMSM servo system is studied and the design proceeding of a first-order ADRC in the current-loop is elaborated. Through disturbance estimation and feedforward compensation, the disturbance in current loop can be eliminated. Then, by taking use of ADRC controller and the analysis of digital control delay effect, an improve method focus on delay element has been proposed. By taking these measures, the current response can reject t disturbances,eluminate the effect of delay time and improve the bandwidth nearly to double. Simulation and experimental results show the effectiveness of the proposed method.Next, considered about the parameter vary will result in a degradation of controller, a robust analysis of ADRC has been carry out to make sure how the parameter changes effect the controller, and ensure the most significant impact parameter, according to this conclusion, an on line parameter identification method based on Model Reference Adaptive System(MRAS) is adopted to identify the inductance and flux. By simulation and experimental results verify the correctness of the analysis and the effectiveness of identify method.