The Research On Current Control Technology Of AC Asynchronous Servo Motor

AC asynchronous servo motor high-speed drive control system is an essential part of top-grade Computer Numerical Control(CNC)machine tools.However,at present,high-speed drive control technique of our country has a big gap with that of Europe,the United States,Japan and other developed countries.Thus,research on AC asynchronous servo motor high-speed drive control technology is of great significance to the development of China’s high-grade CNC machine tools.And the current control of AC asynchronous servo motor is a key technology.Here,AC asynchronous servo motor is regarded as control project,and its field-weakening control and current decoupling control techniques have been deeply investigated.The vector control mathematical model of AC asynchronous servo motor is established.Based on this model,the operation constraint characteristic and current coupling effect of AC asynchronous servo motor are studied.Then,the overall implement plan of AC asynchronous servo motor current control is put forward.The operation condition of AC asynchronous servo motor in the whole frequency range is discussed.Base on the voltage and current constraints of the motor in different operation regions,the theoretical optimal vector value trajectory for achieving maximum torque output is determined.To deal with the problem that the trajectory has a great dependence on the motor parameters,the idea of closed-loop control is introduced after the principles,pros and cons of traditional“1/ω_r Field–weakening Control Algorithm”are analyzed.Then,a closed-loop field-weakening control strategy based on voltage coordination control is brought forward to optimize the current allocation under dynamic torque.The design principle of traditional current PI controller is analyzed.And to solve the coupling problem of excitation current and torque current in vector control,complex-plane vector control method is adopted.Then,based on the traditional current PI controller,complex-plane PI current decoupling controller is constructed.Due to the saturation phenomenon of integrate part in PI controller,an Anti-Windup control structure is used.The simulation platform and experimental platform for AC asynchronous servo motor current control system have been built to efficiently simulate and experimentally verify the as-proposed field-weakening control algorithm and current decoupling controller.