The Study of Parameters Calculation and Structural Optimization for High-Speed Slotless Permancent Magnet Brushless DC Motor
|Course||Motor and electrical|
|Keywords||No cogging High - speed permanent magnet motor Soft ferrite Inductance Optimization|
The high-speed permanent magnet brushless DC motor has a power density, geometry, fast dynamic response, high operating efficiency advantages in high-speed operation occasions has broad application prospects. However, the high alternating frequency of the high-speed state of permanent magnetic machine stator iron losses, severe fever, cogging torque can cause torque ripple, seriously affect the accuracy of the system's control. In this paper, a high permeability soft ferrite, a high resistivity, low cost, and as a high-speed permanent magnet brushless DC motor stator core, stator without alveolar structure, can effectively reduce iron loss and thoroughly eliminate the influence of the cogging torque. This article is focused on the structure of the motor, the magnetic field distribution, the optimization of the design and control system study. First, based on the characteristics of the of soft ferrite high permeability, high resistivity soft magnetic ferrite bead as the motor stator core, rotor NdFeB permanent magnetic ring constituted without cogging motor structure, the the internal magnetic field of the motor, in-depth analysis. The one hand, by analyzing the characteristics of the air-gap magnetic field distribution of the non-cogging motor, it is pointed out that this kind of motor is large effective air gap magnetic field distribution is very uneven, winding emf induced in the conductor position. Therefore, the introduction of non-analytical calculation of the air-gap magnetic field of the alveolar structure motor, derived induced electromotive force of the motor winding, by comparison with finite element calculations and measured to prove the correctness of the calculation method for the The type of motor design calculations provide a theoretical basis. On the other hand, due to the motor air gap of the alveolar structure, leading to the end of the magnetic flux leakage serious this paper, three-dimensional finite element analysis of the ends of the magnetic field of the motor, pointed out that the magnetic flux leakage of the end of the air-gap magnetic field near the end The serious motor design must consider the impact of this factor. Second, due to the stator winding inductance characteristics of permanent magnet brushless DC motor, permanent magnet brushless DC motor air gap without alveolar structure very serious end leakage magnetic field, coupled with its longer end coils, resulting in the leakage inductance of the motor end, the the traditional motor winding inductance calculation method is no longer applicable, therefore, this article uses the energy method to calculate the inductance of the straight part of the stator windings, starting from the basic theory of the electromagnetic field, the derivation of the leakage inductance of the end The method of calculation. By comparison with finite element calculation results and experimental results prove that this derivation of the winding inductance calculation method is correct, the electromagnetic properties of the alveolar structure of permanent magnet brushless DC motor provides a strong basis for accurate research. Again, due to the low stator soft ferrite saturation magnetic induction (0.4T) rotor Nd-Fe-B permanent magnet materials point, it is necessary by the size of the stator and rotor reasonable match to enable them to reach their optimum operating point, therefore reasonable match of the stator and rotor size is the key problem of such motor design. The first phase winding induced emf analytical calculation based on derived analytical calculation expression of the motor power density, and thus has an important influence motor structure size of the size of its power density. Then, the power density of the motor unit volume for the target, the motor stator inner diameter and the outer diameter of the permanent magnet as the optimization variables to construct the the motor structure size optimization model using genetic algorithm to determine the motor stator and rotor size, resulting in a class motor stator and rotor match the size of the basic design. The last two methods, Matlab simulation and finite element simulation results verify that the motor is optimized soft ferrite cores and the operating point of the Nd-Fe-B permanent magnetic ring matching more reasonable, the power density of the motor have been significantly improved. The above method can be applied to the type of motor electromagnetic design process, improve the level of such motor design with high theoretical value. Finally, based on the dsPIC30F2010 enhanced 16-bit the flash digital signal controller using space vector modulation method, sinusoidal brushless DC motor drive control system design and debugging. Actual commissioning tests, the initial realization of a sinusoidal drive motor the ideal experimental waveforms, motor speed, torque and smooth, vibration and noise has been improved.