Research On Iron Loss Analysis Of Multiphase Induction Motors

Multi-phase induction motors have broad application prospects in places where high reliability and high-power power equipment are required due to their many advantages such as stable operation,high fault tolerance and simple structure.As an important performance index of multi-phase induction motor,iron loss has an important impact on the running performance of the motor and the energy consumption reduction.However,due to the complex factors such as different magnetization modes of motor tooth and yoke,cogging harmonics,and saturation of the magnetic circuit,the calculation of the iron loss of the motor has always been a difficult point in the motor design process.This thesis starts from the perspective of theoretical analysis and numerical calculation,and conducts in-depth analysis and research on the iron loss of multi-phase induction motor,and explores its influencing factors.The structural principle of the multi-phase induction motor and the physical mechanism of iron loss are introduced.From the microscopic point of ferromagnetic material,the causes of hysteresis loss,eddy current loss and abnormal loss in the alternating magnetization mode and the mathematical model are given.The limitations of the alternating magnetization iron loss model are explained,and the principle of rotational magnetization loss unique to rotating electrical machines is analyzed.The classification of the iron loss of multiphase induction motors is illustrated.The calculation formula of the iron loss of the motor and the calculation model of the iron loss separation which can account for harmonics,local hysteresis loop and rotating magnetization are respectively introduced.The characteristics of the above two calculation methods are analyzed,which lays a theoretical foundation for the analysis of iron loss.According to the time-step finite element field-circuit coupling principle,a unipolar two-dimensional time-step finite element field-path coupling model of multiphase induction motor is established.The equivalent processing of the motor end windings and the integration of the end circuit equations into the electromagnetic field equation greatly reduce the complexity of the modeling and the solution time.The magnetic flux variation waveform of the typical position of the motor core is analyzed,and the magnetization characteristics of different parts of the core are obtained.Based on the classical iron loss separation model,the calculation model of iron loss based on finite element method is established.The loss coefficient of the model is obtained by data fitting,and the iron loss value of multiphase induction motor under different operating conditions is calculated.The distribution law of the iron loss density of each part of the motor is obtained,and the calculation result of the iron loss formula is compared.The factors influencing the iron loss of multiphase induction motors are explored.According to the principle of control variable method,the effects of magnetic wedge,stator slot size and stator chute on the iron loss of the motor are studied separately,and the influence of different factors on the magnetic field and iron loss of the motor is obtained.The work done in this thesis has important reference value for the design and optimization of multiphase induction motors.