Research On Permanent Magnet Synchronous Motor Current Sensorless Servo Control Technology

With the development of permanent magnet materials and the progress of digital control technology,the servo control system of permanent magnet synchronous motor(PMSM)has been widely used in the high-tech fields such as CNC machine tools,robots,pan-tilt and so on.Higher requirements are put forward in the performance,reliability and cost of servo control systems.Therefore,the motor control technology to reduce various sensors has been widely concerned and researched.The research mainly focused on position sensorless control,and the current sensorless control research is not deep enough,so the theoretical analysis and system modeling are necessary.At the beginning of this paper,the development of servo control system is introduced,and both domestic and foreign research status are summarized.Taking the small power surface permanent magnet synchronous motor as the research object,firstly,the mathematical model of the Surface Permanent Magnet Synchronous Motor(SPMSM)is established,and the mathematical model under the three-phase static coordinate system and synchronous rotating coordinate system are obtained respectively,and the principle of the motor field orientation control is described.The control principle of i_d=0 control,backstepping adaptive control and current prediction control are introduced.The servo control system based on current estimation is studied,and the design process of the controller paramaters is introduced in detail.A dead time compensation scheme is designed based on the dead time influence analysis.The effectiveness of the system is verified by positon control simulation and experiment.According to the servo application characteristics of small power,small load fluctuation and low speed,a servo control system based on no current loop is studied.The current inner loop is eliminated by simplifying the motor voltage equation,and the design process of the controller parameters is introduced in detail.The effectiveness of the system is verified by positon control simulation and experiment.Finally,the performance of the two servo control systems is compared.The system bandwidth is compared by open loop bode diagram.In order to study the influence of motor parameters variation,the robustness of motor parameters is analyzed by closed-loop zero pole map of the system,and verified by several groups of simulation.Finally,considering the complexity,bandwidth and motor parameter robustness of the control system,the performance of the two servo control systems is evaluated from multiple perspectives.