Research On Control Technology Of High Speed Hollow Cup Motor

The hollow cup motor is a type of high-speed,high-precision motor.With its fast response speed,high power density,stable operation and good servo performance,it is widely used in military,aerospace,medical equipment,automation equipment and other high-speed and high-precision occasions.In the hollow cup motor control system commutation error will restrict the performance of the control system,and the accuracy and stability of the motor decrease,in addition to the torque ripple will also affect the stability of the motor operation,in order to improve the performance of the hollow cup motor control system,this thesis on the basis of the commutation error and torque ripple suppression of the motor on the basis of the no position control of the hollow cup motor.Firstly,this thesis introduces the structure of high-speed hollow cup brushless motor,it deeply analyzes the basic principle of the hollow cup brushless motor and constructs the mathematical model of the hollow cup motor,the thesis also introduces the relevant steps of motor control including six-step control method,back potential detection method,rotor starting method and speed modulation method,and analyzes the source of motor commutation error.Aiming at the problem of position-free control of the hollow cup motor,the three-stage position-free control method of the hollow cup motor is adopted.Finally,the high speed hollow cup motor position-free control system is simulated and analyzed.Secondly,the experiment platform of the hollow-cup motor position-free control system is built.The hardware circuit of the control system is designed and the implementation process of the software algorithm is analyzed in detail,which lays a good foundation for verifying the effectiveness of the control strategy proposed in the thesis.Thirdly,the freewheeling state of non-conducting phase under different PWM modulation modes is analyzed in detail.After considering the influence of non-conducting phase commutation freewheeling,switching loss and torque ripple,the power circuit driving mode of PWM-ON-PWM is finally selected,and its implementation method is studied.The commutation angle subdivision program is designed,and the correctness of the program is verified by experiments.Finally,aiming at the problem of commutation error caused by filter sampling circuit,software and hardware delay and sampling delay in high-speed operation of high-speed hollow cup motor,an adaptive commutation correction strategy based on bus current integral is proposed.The objective is to make the integrated current value of the bus current equal before and after half a cycle of the conducting period.The integrated current value of the bus current of the motor is used as a feedback signal to provide closed-loop compensation for the commutation angle.This strategy is validated through experiments.It only requires the detection of the motor’s bus current and does not rely on any motor parameters.