Research On Design And Control Of Slotless Permanent Magnet Synchronous Motor For PTZ

The gimbal integrates visible,near-infrared,and long-wave infrared detection,and can be used for border and coastal defense monitoring,port monitoring,and urban high-altitude observation.Observation of the object should not shake during the rotation of the gimbal.This requires the control of the motor to have a stable torque during operation,and there should be no torque ripple.Moreover,the gimbal requires rotation speed control in the range from ultra-low speed to high speed.Traditional gimbals mostly use stepping motors.Stepping motors have a good control effect under ultra-low speed running status,but the control accuracy is low at medium and high speeds,and the problem of lost steps is prone to occur.In recent years,research on a gimbal motor to meet the requirements of stable running torque and full speed range control of the gimbal has become a research hotspot.Based on the application background of the gimbal motor,this paper adopts a slotless permanent magnet synchronous motor scheme,and carries out corresponding research work on the design of the motor body structure,motor parameter analysis and parameter optimization,full speed range control,etc.First of all,this paper makes an in-depth analysis of the causes of the torque ripple of the permanent magnet synchronous motor.In order to completely eliminate the cogging torque in the operation of the permanent magnet motor,this paper combines the slotless permanent magnet motor and the ring winding to derive A new slotless motor structure using double-layer short-distance windings.The air gap magnetic field and torque ripple of the motor structure model are simulated by finite element simulation.After simulation verification,the slotless permanent magnet motor structure designed in this paper can effectively reduce the motor air gap magnetic field harmonics and greatly reduce the torque ripple,Can effectively solve the jitter problem of the gimbal during operation.Finally,this paper studies the control of the permanent magnet synchronous motor for PTZ in the full speed range.In order to realize the stable control of the full speed range,this paper adopts the speed mode of voltage space vector control in medium and high speed.In the ultra-low speed running state,this paper designs a current open-loop position mode,and realizes the position control of the PTZ motor at ultra-low speed by changing the current phase by keeping the current amplitude unchanged.In addition,a method can be implemented to smoothly switch between the medium and high speed mode to the low speed position mode,which can complete the smooth transition of the gimbal from the speed mode to the position mode and keep the gimbal stable during operation.Finally,the hardware circuit of the full speed range control system of slotless permanent magnet motor is designed.Experiments show that the control system designed in this paper can realize the stable control of the speed of the PTZ in the full speed range.