针对无刷双馈电机在采用传统直接转矩控制方法时存在转矩和磁链脉动大等问题,对无刷双馈电机内部电磁关系、传统直接转矩控制产生脉动的原因进行了分析.在传统直接转矩控制中,当磁链所处位置不同时,所选电压矢量对转矩及磁链幅值的影响也不同.在此基础上,提出了一种基于模糊占空比调制的直接转矩控制策略,并制定了相应的模糊控制规则.将电磁转矩偏差、磁链幅值偏差及磁链角所处位置模糊化后送入模糊控制器,根据制定的模糊控制规则,确定一个控制周期内有效电压矢量的占空比;通过有效电压矢量与零矢量的不同作用时间来减小直接转矩控制时的转矩与磁链脉动.试验结果表明,基于模糊占空比调制的直接转矩控制方法在保持传统直接转矩控制优点的基础上,能够有效减小转矩脉动与磁链脉动,改善了无刷双馈电机直接转矩控制的性能.%To deal with the large ripples of torque and magnetic flux in traditional direct torque control for control system of brushless doubly-fed machines(BDFM), the internal electromagnetic relations of BDFM, and the reasons of pulsation in traditional direct torque control(DTC) are analyzed.In traditional DTC, when magnetic flux is in different position, the influences of selected voltage vector on amplitudes of torque and magnetic flux are different, on this basis,anovel method of DTC based on fuzzy duty ratio modulation for BDFM is proposed, and related fuzzy rules are setup. The electromagnetic torquedeviation, magnetic flux amplitude deviation, and the position of magnetic flux angle are fuzzed and sent to the fuzzy controller; in accordance with the fuzzy rules, the duty ratio of active voltage vector in a control cycle is determined. The ripples of torque and magnetic fluxare effectively reducedthrough different actions of active voltage vector and zero vector.The experimental results show that the proposed strategy keeps the advantages of traditional DTC, and effectively reduces the ripples of torque and magnetic flux, which improves the performance of traditional DTC of BDFM.
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