| The vacuum pump type load motor will encounter the situation of direct exhaust air when working,and the speed of the vacuum pump motor will drop rapidly or even stop,so that the vacuum degree of the system will decrease and affect the quality of the product,so it is necessary to improve the impact resistance of the motor.At present,the drive motor for vacuum pump usually uses control,the dynamic characteristics of this control mode is poor,and the stability of the system is low in the face of impact load.In view of this situation,a canned variable frequency asynchronous motor for vacuum pump is designed,and a control system is developed to study the stall characteristics of vacuum pump under impact load,and a variable winding number of turns is proposed to further lift the variable frequency for vacuum pump in a short time impact resistance of frequency asynchronous motors.First of all,by optimizing the motor body structure to enhance the impact resistance of the motor.For a 1.9kW vacuum pump with canned frequency conversion asynchronous motor optimization design to enhance the maximum torque multiple of the motor.use commercial software to analyze motor parameters and conduct electromagnetic simulation in twodimensional field.the maximum torque multiple is optimized to enhance the impact resistance of the motor.The experiment of rated load temperature rise,constant frequency load characteristic and variable frequency speed regulation characteristic are carried out to verify the rationality of motor design scheme.Secondly,in the control mode of vacuum pump system,the influence of the two control modes on the impact resistance of the motor is compared and analyzed.In order to establish the control system model,the vacuum pump is equivalent treated with canned variable frequency asynchronous motor.Adding shield sleeve makes the T equivalent circuit of canned variable frequency asynchronous motor different from ordinary asynchronous motor.The model reference adaptive(MRAS)control system based on PI controller is established to control the frequency conversion asynchronous motor for vacuum pump,and the control model is established by simulation software,and the system is simulated and analyzed.Then,the simulation results are analyzed and processed,and the difference between the actual speed and the predicted speed is compared.An open loop constant voltage frequency ratio control system is established,and the simulation results of the two systems are compared under the same conditions.The MRAS control system based on PI controller has better dynamic characteristics and impact resistance.So that the vacuum pump system can ensure the stability of the operation,to avoid direct exhaust atmosphere or vacuum cover leakage caused by the motor deceleration or even shutdown,resulting in the vacuum environment reduced.Finally,the shock resistance of the variable frequency asynchronous motor for vacuum pump is further improved in a short time by series and parallel switching.The advantages and disadvantages of this method are analyzed and given.Based on this method,a method of variable winding turn number is proposed,and the switching principle,flow,control block diagram and implementation effect of this method are studied. |
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