Research On Coordinated Control Of Dual Direct Drive Gearless Asynchronous Motor For Roots Vacuum Pump

With the continuous development of vacuum application technology,the demand for vacuum pumps in the fields of extremely large-scale integrated circuit manufacturing equipment industry,thin film technology and electric vacuum technology is increasing.Traditional Roots vacuum pumps use 1: 1 gears to drive the yin and yang rotors to perform synchronous rotation in the opposite direction to prevent the "8" shaped Roots rotors from colliding together.However,after long-term operation,gears with even higher machining accuracy will inevitably have gaps.When the tooth-side gap is larger than the minimum gap between the rotors,a failure will occur and the system will be shut down,which will greatly affect the vacuum environment required by the production process and economically loss.In response to this situation,a dual-motor direct-drive control system is designed in this subject,which can meet the requirements of control indicators.(1)According to the technical requirements of the asynchronous motor for the vacuum pump,designed an asynchronous motor for the vacuum pump with a power halved.With two-dimensional finite element business software,the electromagnetic field simulation calculation is performed to meet the requirements of the index,and the design scheme and specific electrical parameters suitable for the gearless roots vacuum pump driving asynchronous motor are obtained.(2)According to the principle of vector control,combining coordinate transformation and rotor field orientation,a simulation model of asynchronous motor based on rotor field orientation is established to achieve high-performance decoupling control,which has a better reliability and stability,making a good foundation for the construction of dual-motor system;(3)Based on the single-motor control system,a dual-motor control system is constructed by comparing main order control,master-slave control,deviation coupling control strategies.In the deviation coupling control structure studied in this paper,the core subsystem speed compensator has been improved creatively to make up for the shortcomings of the existing speed compensator is limited to speed synchronization.The improved scheme in this paper can achieve speed synchronization and eliminate position synchronization error,and the construction of position loop can be omitted,so that the response speed index of system can be improved.The four common operating conditions of vacuum pump systems are analyzed in detail and also carried out a differential analysis of the load sudden change time.The results show that the synchronization effect of the improved deviation coupling control is significantly better than the other three control strategies,which can improve the control performance of electric drive system of vacuum pump;(4)On the basis of(3),considering the influence of motor parameter differentiation,an extended analysis is performed according to the analysis route of(3).The results show that the speed and position synchronization error of the dual-motor direct-drive system can be greatly reduced with improved deviation coupling control,which can further improve the control accuracy of electric drive system of vacuum pump.