Research On Key Technologies Of Brushless DC Motor Control

The brushless DC motor(BLDCM)is widely used in every field of national economy at present,such as household appliances,information products and office automation,transportation and industry because of highly desirable features,such as simple structure,run smoothly,high torque/weight ratio,economical efficiency,simpler control system compared with the induction motor,has the favorable govering performance of the DC motor,and so on.In this paper,the brushless DC motor control as the background to study the control strategy of torque ripple suppression for brushless DC motor,and verified by experiment.Firstly,the research background and current situation of brushless DC motor are introduced.The structure of the brushless DC motor is introduced,and the working principle is analyzed,the brushless DC motor is widely used in the household appliances,information products and office automation,transportation,industrial and other fields;Design and realization of hardware circuit of brushless DC motor control system,the selection of power devices,filter capacitor,drive circuit power,signal detection circuit,and DSP control circuit is designed.Secondly,the mathematical model of brushless DC motor are introduced.The equation of voltage and electromagnetic torque are shown in three-phase stationary coordinate system,the mathematical model of brushless DC motor during the commutation interval is analyzed in the two-phase stationary coordinate system;Aiming at the commutation torque ripple of brushless DC motor,a graphical control method based on coordinate transformation is introduced to analyze the constraint condition of no torque ripple and the minimum commutation time;In order to avoid commutation failure at full speed,a coordinated control method is proposed based on the graphic method to reduce the commutation torque ripple and commutation time;In order to improve the rapidity and robustness of the system,a control method of hysteresis control for suppressing commutation torque ripple of the brushless DC motor is introduced.The commutation process and control strategy of motor operation and braking operation are analyzed.Thirdly,Aiming at the torque ripple caused bynon-ideal EMFof the brushless DC motor,a method of suppressing torque ripple during commutation interval and non-commutation interval of the brushless DC motor is based on the dead-beat control(DBC)strategy.The mathematical model during commutation interval and non-commutation interval of the brushless DC motor,the working principle of the DBC and the design of control system is analyzed.Finally,according to the above control strategy and the design of hardware and software,building the experimental platform of thebrushless DC motor at laborator.Through experimental results,validating the correctness and effective of the proposed strategy.