Reserch On Permanent Magnet Brushless DC Motor With Low Ripple Torque

Permanent magnet brushless DC motor is a new type of high performance motor,has the advantages of high efficiency,long life,low noise and better speedtorque,widely used in industries,defense,aerospace and home appliances.However,permanent magnet BLDC motor has a winding current commutation process.The current pulsation in this process will produce a significant pulsating torque.Its maximum value can reach 50% of the electromagnetic torque which affects its application in the situation with low ripple torque.Therefore,how to reduce and suppress the pulsating torque has become a research hotspot in the field of application research of permanent magnet BLDC motors.In related literatures,at present,most of the research on pulsating torque is still in the simulation stage,and there are few research results that have actually been applied.Our group measured the pulsating torque of the existing permanent magnet BLDC motor products through the permanent magnet rotation angular acceleration sensor developed in the earlier stage and found that the pulsating torque is still obvious.Therefore,the research on the suppression of the pulsating torque of permanent magnet BLDC motors and the substantial improvement of the suppression effect of pulsating torque have very important practical significance for the further promotion and application of permanent magnet BLDC motors.Our group proposed a dual-stator and dual-rotor motor system based on peakvalley complementary suppression of pulsating torque,has achieved a good effect.But in fact,since the electromagnetic parameters and control parameters of both motors are discrete,there have significant differences in the symmetry of the pulsating torque waveforms of the two motors.Therefore,although the ripple torque is significantly suppressed,there is still room for improvement in the suppression effect.On the other hand,the dual-stator and dual-rotor motor systems are relatively large and complicated.This thesis further proposes a principle and physical model of a lowpulsation torque single-stator,single-rotor dual-winding permanent magnet BLDC motor based on the peak-valley complementary suppression torque method,combining the original dual-stator,dual-rotor motor system into a single-stator,single-rotor dual-winding motor system and generates two more symmetricalpulsating torque waveforms to cancel.At the same time,the dual-drive coordinated control system is designed to realize the coordinated control of the current of the two winding systems,to ensure that the two motor systems provide the same superimposed average torque to the load at the same operating point,and to improve the suppression effect of the ripple torque.Finally,design grating position sensor to replace the hall position sensor to improve the commutation accuracy of the permanent magnet BLDC motor and further optimize the sine and symmetry of the ripple torque waveform.In this thesis,a single-stator,single-rotor dual-winding permanent magnet BLDC motor body is developed by establishing a mathematical model of a new type of motor corresponding to the actual situation.Then,design a control system including BUCK voltage regulator circuit,drive system circuit and current coordinated control strategy.In the last,establish BLDC experimental platform with low ripple torque.Through the actual measurement of the pulsating torque,it is proved that the amplitude of the pulsating torque is further reduced compared with the dual-stator and dual-rotor permanent magnet BLDC motor system,which provides a new method to achieve ripple torque suppression.Also,It is a great significance to promote the further popularization and application of permanent magnet BLDC motors.