| In the context of accelerating to change the economy-growth mode, the promotion and application of energy-conserving techniques have become the key point of industrial development. The power consumption of industrial motors make up 2/3 of the country’s total electricity consumption, and promoting the high efficiency motor is a top priority on adjusting the product structure of the middle and small motor at present. The switched reluctance motor (SRM) as the high efficiency and adjustable speed motor appeared in our country as industrial product since the ’90s, but the SRM has always been restrained by vibration, acoustic noise and torque ripple in decades..The SRM is a significant competitive adjustable speed motor for its simple structure, high reliability, high efficiency, low cost, etc. In our country it has been successfully used in electric vehicle driving, coal mining and oil field mechanic equipment, forge press machines, household appliances and textile machinery. On account of its rotor without permanent magnet or winding, the SRM could be applied in abominable environment with high reliability. In terms of performance, the SRM have many advantages such as frequently positive and reverse rotation, good speed adjustment feature, strong overload capability and high efficiency. Because of its doubly salient structure, control method, saturation and nonlinearity effect, the vibration, acoustic noise and torque ripple are more significant than permanent magnet machine or asynchronous machine, what is the focused research area for SRM all the time. This thesis has researched separately from new SRM structure design, improved magnetic field calculation method, high precise position detection equipment design, control strategy design for reducing torque ripple and switched reluctance motor drive (SRD) system design. New designs for restraining vibration and torque ripple are proposed systematically, which have theoretical value and engineering significance.In the first chapter of the thesis, the research aim and significance is introduced. Then the research status of areas for SRM are presented, which includes the method of reducing vibration and noise, the magnetic field analysis based on magnetic field division method and rotor position detection method. And this thesis puts emphases on design method of the SRM and control strategy for vibration and torque ripple reduction.In the second chapter, this thesis presents a new type rotor tooth with slot on each side. By rotor profile changed, the direction of air gap flux density is altered on surface of rotor and the radial magnetic flux density would be decreased as well as the tangential flux density increased. As a result, the reduced radial force wave would depress the vibration. Meanwhile the slotted rotor would improve the torque performance of SRM. Subsequently three rotor slotting styles including one-sided slotting, two-sided slotting and pole-shoe shape are compared. Based on finite element analysis(FEA), it is concluded that the slot on the reverse side toward to rotating direction has no influence on performance of SRM, so two-sided slotting style could gain the same results in forward and reverse rotating direction. The pole-shoe shape leads to a little higher torque ripple, but the maximum radial force wave are same with these three slotting styles. Slot width, slot depth and tooth roof height are three key dimensions for slotting, in this chapter, the influence rules that these key dimensions affect torque ripple, radial force wave and average torque are researched, and gained the optimal slot dimensions using FEA. Calculating the weakened percentage of radial force wave, it is concluded that the effect of vibration reduction is best when phase conducts initially. With the angle between center lines of rotor and stator teeth decreasing, the level of vibration reduction will get down. The method Slotting on the rotor which has low manufacturing and alteration cost possesses good engineering significance.In chapter three it is proposed an improved method of magnetic field partition based on parabola arc formula to calculate the air-gap permeance of the SRM with complex rotor or stator profile. This method has higher precision than that based on arc, and has more concision than that based on elliptic arc. Dividing the relative position between rotor and stator into three intervals, air gap permeance and flux density of these intervals are computed respectively in normal SRM and the SRM with slotted rotor based on this improved method of magnetic field partition. In this chapter, a means of analytic calculation on the weakened percentage of radial force wave is proposed, which adopting the ratio mode to calculate the reduction extent of radial force wave by air-gap permeance changed. In this method there is no calculation on specific value of radial force wave, but the reduction extent by ratio. In the process some nonlinear variable such as current, inductance and flux linkage need not be considered. It’s only needed to compute the variation of permeance with the change of air gap shape. According to this method, the reference could be obtained for vibration suppression designs on changing stator or rotor profile for the other type of doubly salient machine, which could improve the optimal design efficiency. After that it is compared the results of the weakened percentage of radial force between method of magnetic field partition using ellipse and parabola path. Because having no consideration of magnetic saturation and flux leakage, the results of magnetic circuit calculation are a little higher than FEA entirely, but the results of using parabola path are closer to FEA. Finally two SRM prototypes are produced to conduct a comparative experiment for vibration. The vibration acceleration of prototype SRM with slotted rotor is obviously smaller than the normal one, but there is a slight decline on efficiency. Actual measurement of the weakened percentage of radial force is closed to the numerical results, which proves the improved magnetic circuit method is valid and precise. The experiment also verifies the method of vibration reduction proposed in chapter two.A SRM rotor position detecting system based on variable reluctance resolver(VR) is designed in chapter four, which can provide the excitation to VR and output high-precision incremental encoder format position signal up to 16384 pulse per round. The high-precision position signal can meet the requirement of the servo control.A new control strategy for instantaneous torque based on current tracking is proposed in chapter five. This method use curves on torque-position angle plane gained from FE model to establish the set of torque curves expressions by curve-fitting numeric analysis. Then the mapping function between chopper current and instantaneous torque is obtained. By controlling current, the objective torque could be acquired, which could be adjusted to reduce the torque ripple. The advantage of this method is the concision of mapping function, which has less amount of calculation suited to real-time control. This method is proved by FEA.In chapter six a SRM drive system is designed to realize motor speed regulation and control algorithm. This system includes control board with F2812 DSP and power drive board with IGBT. This chapter introduces the main hardware circuit and software function. In prototype motor experiment, this SRD system is applied. |
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