Research On Diagnosis And Evaluation Of Unbalanced Stator Winding Fault For BLDC Motor

The balance status of motor stator winding will directly affect the normal,stable and efficient operation of motor control system.It is of great significance to carry out the research of online monitoring the balance status of motor stator winding,while the motor in operation.There are many kinds of faults that cause unbalance of motor stator winding,among which high resistance connection(HRC)and inter-turn short circuit faults are common stator faults.The detection method of BLDCMs stator winding unbalance fault has few reported,so this paper proposes a research method for the detection of HRC and inter-turn short circuit fault in a BLDCM.In this paper,the BLDC motor model 57 BLF is manually connected with different resistance values in different phases to simulate the HRC fault.It also introduces the simulation experiment and physical experiment device,the acquisition and analysis of simulation signal,constant speed experiment signal and variable speed experiment signal.In the same way,for the model 6710 external rotor BLDCM,the number of turns of stator winding with different proportion is artificially short circuited in different phases to simulate the inter-turn short circuit fault,and the simulation experiment and physical experiment analysis are carried out.According to the working principle of the BLDCM,the change rule of current and voltage in the control system of the BLDCM is studied,and the balance resistance network is introduced to obtain the zero-sequence voltage component of the motor in the control system.Combined with the theoretical formula derivation of the system loop,and according to the regular change of zero sequence voltage component and current under different fault phases,a two-step strategy for the detection,localization,and evaluation of HRC fault and inter-turn short circuit fault in a BLDCM is proposed.Specific implementation steps:In the first step,the zero-sequence voltage component(ZSVC)of the motor is collected and analyzed,and the HRC and inter-turn short circuit faults are detected according to the amplitude of the fundamental frequency component of the ZSVC spectrum.In the second step,once the unbalanced fault has been detected,three indicators are calculated from the ZSVC and three-phase currents to localize the fault phase,and then the fault severity is estimated according to the theoretical formula.Theoretical,simulated,and experimental analyses have been performed,and the results of them are consistent with one another,thereby validating the effectiveness of the proposed strategy.The method proposed in this paper is suitable for the BLDCM with trapezoidal wave back EMF,which has the advantages of small calculation and low cost.The detection algorithms of HRC fault and inter-turn short circuit fault and the control algorithm of motor are implemented on a single microcontroller unit in real time,which makes the proposed strategy efficient and flexible in industrial applications.