Research On BPNN PID Control And Speed Sensorless For A Bearingless Induction Motor

In recent years,with the development of industry and advancement in science and technology,the motor theory and its control technology have also developed rapidly.A Bearingless Motor has broken the theoretical category of traditional motors through the interaction of the two sets which was winded in the stator slot,it generated electromagnetic torque to drive the load and levitation force to supporting the rotor at the same time,while achieving the frictionless rotation and suspension of the rotor.At present,it has become one of the key research directions in the fields of special electric drive and magnetic levitation.A Bearingless Induction Motor(BIM)has advantages of simple structure,low mechanical noise,high mechanical strength and low cogging torque in a wide range of bearingless motors.It is very suitable for ultra-clean and strong corrosion.The use of vacuum and other harsh environments is one of the key research directions in the fields of medical devices,food processing,aerospace and other special transmissions.Under the support of the Natural Science Foundation of China(51475214)and the Natural Science Foundation of Jiangsu Province(BK20141301),based on the introduction of bearingless motors,the research background,current situation,application fields and development direction of BIM are discussed.Then,the development of PID control and speed sensorless development is described.Then the BIM mathematical model was established,and then the air gap magnetic field orientation control system based on this model was built.Firstly,we discussed the development direction of the BIM based on the introduction of bearingless motors,and the development of PID control and speed sensorless development was described.Then,the mathematical model of the BIM is established,and the BIM vector system based on air gap magnetic field is constructed.Secondly,for the problem that PID control is difficult to obtain the best adjustment parameters during the operation of the BIM,a BPNN PID control method is proposed.This method uses a 3-layer BPNN PID controller,setting the given value,measured value,and the deviation of them to BPNN.By setting the performance index function,the weight of the network is corrected according to the gradient descent method,and online adjustment of the parameters of the PID controller is achieved.Aiming at the deficiency of mechanical sensors in the BIM operation,a BIM speed sensorless control method based on improved MRAS is proposed.This method is based on the BIM voltage model rotor flux linkage.By adding low-pass and high-pass filters to eliminate the integral link,the speed of the BIM vector control system is identified,and the BIM control system is simulated and analysis by Matlab/Simulink.Finally,using TMS320F2812 as the main control chip and the hardware circuit and software program were designed respectively.The experimental platform of the BIM vector control system was set up and experimental research was carried out.The results show that the established digital control system has good dynamic and static performance and has achieved the expected results.