共查询到20条相似文献，搜索用时 937 毫秒
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针对异步电动机直接转矩控制（DTC）系统在低速时由于开关频率不稳定而引起转矩脉动较大的缺点，提出了一种预测控制方法。该方法根据转矩和定子磁链的误差来确定应该施加的参考电压矢量，最后利用空间矢量脉宽调制（SVPWM）方法来合成该矢量，这样即保证了逆变器的开关频率恒定，从而大大降低转矩脉动。仿真结果表明，在低速下定子磁链轨迹近似为圆，转矩脉动不明显。 相似文献
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异步电机按定子磁链定向的转矩连续控制 总被引：5，自引：0，他引：5
ＮｏｍｅｎｃｌａｔｕｒｅＪｍｏｍｅｎｔｏｆｉｎｅｒｔｉａｏｆｔｈｅｌｏａｄ(ｍｏｔｏｒｉｎｃｌｕｄｅ)ｉｓ,ｉｒ,ｉｍｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｍａｇｎｅｔｉｚｉｎｇｃｕｒｒｅｎｔｕｓ,ｕｒｓｔａｔｏｒａｎｄｒｏｔｏｒｖｏｌｔａｇｅＬｓ,Ｌｒ,Ｌｍｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｍａｇｎｅｔｉｚｉｎｇｉｎｄｕｃｔａｎｃｅＬσｔｏｔａｌｌｅａｋａｇｅｉｎｄｕｃｔａｎｃｅＲｓ,ＲｒｓｔａｔｏｒａｎｄｒｏｔｏｒｒｅｓｉｓｔａｎｃｅＮｐｐｏｌｅｐａｉｒｓΨｓ,Ψｒ,Ψσｓｔａｔｏｒ,ｒｏｔｏｒａｎｄｔｏｔａｌｌｅ… 相似文献
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In order to deal with torque pulsation problem caused by traditional control method for brushless DC （BLDC） motor and to achieve high precision and good stability, a novel control strategy is proposed. Compared with the traditional control scheme, by using phase voltage as a control objective and making waveform of phase current approximately quasi-sinusoidal, torque ripple of BLDC motor is reduced from the original 14% to 3.4%, while toque is increased by 3.8%. Furthermore, by detecting zero-crossings of back electromotive force （BEMF） with non-conducting phases, sensorless control is realized. The new control strategy is simple. It can minimize torque ripple, increase torque, and realize sensorless control for BLDC motor. Simulation and experiments show good performance of BLDC motor by using the new control method. 相似文献
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方菁 《宁波职业技术学院学报》2010,14(2):19-22,39
针对传统的直接转矩控制中存在转矩、定子磁链波动大的问题,提出了一种结合空间矢量调制的模糊神经网络直接转矩控制方法。该方法运用模糊神经网络得到期望的任意相位空间电压矢量,再结合空间矢量调制直接对逆变器的开关状态进行控制,以达到减小转矩、定子磁链波动的目的。最后以TMS320F240为核心搭建了直接转矩控制系统,通过采集实验数据分析结果表明,直接转矩控制系统与传统的直接转矩控制系统相比,磁链和转矩波动明显减少,并且保持了转矩和速度的响应速度。 相似文献
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徐君鹏 《河南科技学院学报》2007,35(3):62-65
Fuzzy systems are currently being used in a wide field of industrial and scientific applications. Since the design and especially the optimization process of fuzzy systems can be very time consuming, it is convenient to have algorithms which construct and optimize them automatically. In order to improve the system stability and raise the response speed, a new control scheme, direct - torque neuro - fuzzy control for induction motor drive, was put forward. The design and tuning procedure have been described. Also, the improved stator flux estimation algorithm, which guarantees eccentric estimated flux has been proposed. 相似文献
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To improve the accuracy of the stator winding fault diagnosis in induction motor, a new diagnostic method based on the Hilbert-Huang transform （HHT） was proposed. The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic, which could effectively avoid the influence of the supply unbalance and the load fluctuation, and directly represent the asymmetry in the stator. Using the empirical mode decomposition （EMD） based on HHT, the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted. Then, the fault characteristic can be acquired. Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method. 相似文献
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Novel high torque bearingless two-sided rotary ultrasonic motor 总被引：3，自引：0，他引：3
LI Xia CHEN Wei-shan XIE Tao LIU Jun-kao 《浙江大学学报(A卷英文版)》2007,8(5):786-792
Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using ex-perimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM. 相似文献
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Influence of PWM Modes on Commutation Torque Ripples in Sensorless Brushless DC Motor Control System
This paper introduces four PWM modes used in the sensorless brushless DC motor control system,analyzes their different influences on the commutation torque ripple in detail,and selects the best PWM mode in four given types to reduce commutation torque ripple of Brushless OC( BLDC) motors,Simulation and experimental results show that the selection is correct and practical. 相似文献
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This paper proposes an analysis and a direct power control （DPC） design of a wind turbine driven doubly-fed induction generator （DFIG） under unbalanced network voltage conditions. A DFIG model described in the positive and negative synchronous reference frames is presented. Variations of the stator output active and reactive powers are fully deduced in the presence of negative sequence supply voltage and rotor flux. An enhanced DPC scheme is proposed to eliminate stator active power oscillation during network unbalance. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. Simulation results using PSCAD/EMTDC are presented on a 2-MW DFIG wind power generation system to validate the feasibility of the proposed control scheme under balanced and unbalanced network conditions. 相似文献
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This paper presents a powerful application of genetic algorithm （GA） for the minimization of the total harmonic current distortion （THCD） in high-power induction motors fed by voltage source inverters, based on an approximate harmonic model. That is, having defined a desired fundamental output voltage, optimal pulse patterns （switching angles） are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation （PWM） waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that if the pulsing-torques are at low frequencies, they can cause troublesome speed fluctuations, shaft fatigue, and unsatisfactory performance in the feedback control system, the 5th, 7th, 1 lth, and 13th current harmonics （in the case of five switching angles） are constrained at some pre-specified values, to mitigate the detrimental effects of low-frequency harmonics. At the same time, the THCD is optimized while the required fundamental output voltage is maintained. 相似文献
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介绍了人工心脏轴流式血泵永磁无刷直流电机换相转矩脉动变化过程．根据影响电机换相转矩脉动的因素,给出了减小电机转矩脉动的解决方案,以使电机运行更加平稳．通过实验波形证实本结论分析正确,可以为电机减小转矩脉动作为参考． 相似文献
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电机定子电阻的变化影响了直接转矩控制系统的低速性能.定子电阻的变化具有非线性、时变性等特点,难以建立精确的数学模型,因此提出了基于小波神经网络的定子电阻线辨识的方案,该网络采用梯度下降算法训练,可用于对定子电阻进行在线的辨识.仿真实验测试结果表明该辨识器能够精确辨识定子电阻值,从而有效地改善了直接转矩控制系统的低速性能. 相似文献
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一种新型高功率密度的正弦波永磁电机 总被引：1，自引：0，他引：1
A novel high power-density PMSM (permanent magnetic synchronous motor) with independent magnetic flux path for each phase is proposed in the paper.The complex mathematic model of PMSM is simplified by decoupling of magnetic flux paths between motor phases.In addition,harmonic compoments are lowered through optimum design of EMF (electric motive force) wave.Thus the ripple torque caused by EMF wave distortion is suppressed. 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｗｉｔｈｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｆｒｅｑｕｅｎｃｙｃｏｎｖｅｒｓｉｏｎｔｅｃｈｎｏｌｏｇｙ ,ｔｈｅｆｒｅｑｕｅｎｃｙｃｏｎｖｅｒｔｅｒｓａｒｅｅｘｔｅｎｓｉｖｅｌｙｅｍｐｌｏｙｅｄｉｎＶＶＶＦｄｒｉｖｅｓｙｓｔｅｍｓ.Ｔｈｅｙａｒｅｕｓｅｄｔｏｒｅａｌｉｚｅｓｏｆｔｓｔａｒｔｉｎｇｏｆｔｈｅｉｎｄｕｃｔｉｏｎｍｏｔｏｒ ,ｗｈｉｃｈｉｓｏｎｅｏｆｔｈｅｉｒａｄｖａｎｔａｇｅｓ.Ｎｅｖｅｒｔｈｅｌｅｓｓ,ｉｎｐｒａｃｔｉｃｅ ,ｔｈｅｉｎ ｖｅｒｔｅｒ ｍｏｔｏ… 相似文献
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乔维德 《深圳职业技术学院学报》2009,8(5):13-17
为在简化开关磁阻电机控制系统结构的同时又能使其具有较快的转矩响应速度,提出一种适用于开关磁阻电机直接转矩控制的神经网络模糊推理控制方案,用神经网络定子磁链观测器取代传统的定子磁链观测器,采用模糊控制算法设计逆变器开关状态选择器,利用MATLAB对系统2种不同控制方法的仿真实验结果进行比较．通过比较发现,本文的控制方法转矩、转速、磁链响应快、脉动小,具有优良的稳定跟踪性能和动态响应。 相似文献
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HU Jia-bing HE Yi-kang 《浙江大学学报(A卷英文版)》2006,7(10):1757-1764
INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge… 相似文献
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高速条件下 ,无刷直流电动机的电流换向产生严重滞后 ,导致转矩下降并伴随脉动 .采用超前导通控制法 ,可有效加快换向过程 ,改善转矩输出能力 ;并采用改进的黄金分割法寻优 ,在线调整最优超前导通角 .仿真与实验结果验证了该控制方案的可行性与有效性 相似文献
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表面磁钢永磁无刷电机电磁转矩的解析法分析 总被引：1，自引：0，他引：1
With the air gap magnetic field distribution of surface mounted permanent magnet （PM） motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are investigated with the Maxwell stress tensor method. Accurate results can easily be achieved using the proposed method without using the tedious finite element analysis （FEA）. In this paper, the electromagnetic torque of a surface mounted PM motor with two phases energized is decomposed into four torque components. This technique is useful not only for the design and optimization of the permanent magnet motor, but also for the choice of control strategy. 相似文献