Research On Mechanisim And Characteristics Of On-line Magnetic Field Adjustment Of Claw-pole Memory Motor

In order to achieve wide speed range,permanent magnet synchronous motor mostly adopts the vector control flux weakening method.However,this method has some disadvantages: the speed range is still limited by the bus voltage and inverter capacity;the straight-axis current increases the stator excitation copper consumption and reduces the efficiency in the high-speed area.In response to the problems above,this paper proposes a flux variable claw pole memory motor(FVCPM).It directly adjusts the magnetization of the permanent magnet by applying a current pulse,so there is almost no excitation loss.First,the structure and principle of the FVCPM are introduced.Due to the requirements of the claw pole structure and the range of flux adjustment,the special features of the FVCPM in the design are analyzed.The internal flux path of the motor is analyzed,the magnetic conductance of each part is calculated in blocks,and the equivalent magnetic circuit model of the motor is established.No-load back-EMF,load torque and other parameters of the motor are analyzed by finite element simulation to determine the rationality of the motor design.Secondly,multiple sets of hysteresis loops of the Al Ni Co sample are measured by the designed magnetic circuit device,from which the characteristics of the Al Ni Co magnetization curve in the magnetic modulation are analyzed,and the laws are summarized.The error of the experimental data is analyzed by finite element simulation.Based on the parallelogram hysteresis model,an improved model is proposed,and the accuracy of the improved model is proved with experimental data.The accuracy of simulation of magnetic regulation of the motor using the model is analyzed.According to the characteristics of the Al Ni Co hysteresis loop during the magnetic regulation,a simulation method using the hysteresis model in the finite element software is proposed.Then,the relationship between flux of the motor and amplitude of the magnetic regulation current is studied through simulation to provide a basis for the motor's magnetic regulation.The internal magnetic field of the motor during the regulation is analyzed,and the reasons for the different currents required for magnetization and demagnetization are explained.The effects of the parallel and series structures of Al Ni Co and Nd Fe B used as excitation in the FVCPM on the regulation characteristics are studied.The feasibility of the regulation is analyzed from the aspects of the uniformity of the Al Ni Co magnetic field and the influence of the armature reaction after the regulation.Finally,the flux linkage,inductance,resistance and other parameters of the motor under different degrees of magnetization are calculated by the finite element simulation.The torque-speed curve of the motor using the conventional flux weakening control and the regulation control of the memory motor under different degrees of magnetization are calculated through the formulas respectively.From the aspects of speed regulation range,output torque,etc.,the advantages of the regulation control are explained in comparison.Aiming at the highest overall efficiency,the flux regulation scheme of the regulation control is studied.