Iron Losses And Transient Temperature Field Of Permanent Magnetic Synchronous Motor

The Permanent Magnetic Synchronous Motor (PMSM) has been widely applied in industrial and agricultural production field for its fine speed torque characteristics and low noise, high efficiency, wide speed regulation ability and many other fine performances. With the technological development of PMSM design, many propblems of PMSM need to be further researched, such as the calculation of stator iron losses, the permanent magnet (PM) eddy current loss, the transient temperature rise of PMSM at special operation condition, the proper choice of design parameters, and the distribution of copper loss and iron loss, etc. It is great significance for improving the performance and optimum design of PMSM to further study on these problems.The accurate calculation of PMSM stator iron losses helps analyze the PMSM performance, and calculate for temperature rise of PMSM. In order to accuratly calculate the stator iron losses, based on the orthogonal equivalent analysis of rotating magnetic field, this paper presents one kind of calculation method of stator iron losses with considering the alternating and rotating magnetic field. The elliptical method calculation results is more coincidence with the measurement results than the harmonic balance analysis method. Due to adopt the elliptical method and harmonic balance analysis method calculating the stator iron losses, not only need to determine the waveforms of flux density in stator, but also need to do the harmonic analysis and complex post processor, so it is inconvenience for motor manufacturing plant to computate the iron losses. This paper presents an iron losses calculation method of combination filed and tradition formula, its calculation results is also coincidence with the measurement results. Furthermore, based on the numerical calculation of iron losses, the lead and lag control of PMSM load current influences on the iron losses is studied, and which can be referenced for the choice of control strategy.The calculation for PM edyy current loss is one key problem for the PMSM design. It will cause the temperature rise of PM, the change of magnet performance, and influence on the operation performance of PMSM. At present, some reseaches have been made on the PM eddy current loss, but most of them only focus on the high speed PMSM. In this paper, the principle of PM eddy current loss is analyzed, and a rather large losses can be generated in the PM of PMSM which running at low speed. The influence of amature magnetomotive on PM eddy current loss is analyzed, futuremore, the problem of PM eddy current loss of the PMSM at no load operation is researched. The qualitative relationship between the value of eddy current losses in PM and different PM shape, different number combination of poles and slots are studied. The PM eddy current loss of PMSM with different magnitude of notch and running at different speed is also calculated, calculation and practical measurements results are in stisfactory agreemeng. The PM eddy current will be influenced by the PM shape, the number combination of poles, and slots, and the influence of number combination of poles and slots is more obvious. The PM eddy current loss of PMSM can be reduced by partition PM structure.The temperature rise not only reduces the PMSM operation performance, but also influences the life time and reliability of PMSM. According to the theory of heat transfer and aerodynamics, the equivalent thermal conductivity is introduced to instead of the heat convection in air gap, the whole region FEM model of the 3D transient temperature field for PMSM in the state of steady electromagnetic field is established, hypothetical conditions and boundary conditions of the solved region are presented, and the correlation of temperature field between the stator and rotor of PMSM is settled. The time-variable copper loss thermal resources and iron losses thermal resources spacial discrete loading style are presented. By means of this method, the actual thermal condition of PMSM is more correct simulated and the calculation accuracy is raised. The iron losses and PM eddy current loss are the main reasons for the temperature rise of PMSM. Whether or not considering the iron losses and their non-uniform distribution will affect the calculation results of the motor temperature field. The magnitude of notch affects the PM eddy current loss rather significantly and therefore does a great influence on the motor temperature field, so the accurate calculation of this eddy loss is essential. The series mode coupling method for calculating the short-time over load temperature rise of PMSM is firstly presented, which can be better at instructing motor design and predicting the thermal state of PMSM.Considering the running characteristics of PMSM, the temperature field of PMSM running at its locked-rotor and crawling operation is calculated respectively. By the analysis, it is found that the distribution of copper and iron losses is much more important at PMSM locked-rotor operation. Considering temperature rise limitation and distribution of copper and iron losses, the thesis proposes a structure parameters design method, deduces the temperature rise estimating expression, and further studies the copper and iron losses variation caused by PM temperature sensitivity, which supplies the references for the further optimum design PMSM.