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一种消除无刷直流电动机换相转矩脉动的PWM调制策略 被引量:48
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作者 石坚 李铁才 《中国电机工程学报》 EI CSCD 北大核心 2012年第24期110-116,18,共7页
无刷直流电动机由于本体设计和特有的控制策略存在较严重的转矩脉动问题。为了解决这一问题,提出一种简单的消除换相转矩脉动的换相区PWM调制策略。在换相时,通过三相配合调制,将换相过程中的每个PWM周期分成包含5个中心对称区间的3个... 无刷直流电动机由于本体设计和特有的控制策略存在较严重的转矩脉动问题。为了解决这一问题,提出一种简单的消除换相转矩脉动的换相区PWM调制策略。在换相时,通过三相配合调制,将换相过程中的每个PWM周期分成包含5个中心对称区间的3个功能区。通过计算给三相中的每一相分配不同的调制占空比,使关断相电流的下降速度和导通相电流的上升速度在每个PWM周期内保持相等。所提方法不仅可以消除转矩脉动,还可以通过不同的功能区比例组合来调节换相持续时间。给出所提方法的推导过程,并通过实验验证了所提方法的正确性和可行性。 展开更多
关键词 无刷直流电动机 换相转矩脉动 三相配合调制 换相时间
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微生态发酵技术在肉牛配合饲料原料预处理上的应用 被引量:2
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作者 李权 《中国牛业科学》 2016年第3期56-58,共3页
为提高肉牛养殖效益,本文从肉牛配合日粮的加工调制入手,探索采用微生态发酵技术,对于拓宽牛配合日粮的加工调制途径,提高了饲料的适口性和营养价值,改善了牛舍小气候环境,促进了养牛业的健康发展提供一定的理论参考。
关键词 微生态发酵技术 肉牛 配合日粮调制 应用
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一种合成电流控制的无刷直流电机转矩脉动抑制系统 被引量:22
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作者 李珍国 王江浩 +1 位作者 高雪飞 方一鸣 《中国电机工程学报》 EI CSCD 北大核心 2015年第21期5592-5599,共8页
具有非换相相电流反馈的无刷直流电机的传统双闭环调速系统,因非理想梯形波反电势和非理想方波相电流存在较大转矩脉动,该文引入正比于瞬时转矩的合成电流变量,并推导出每个扇区下的合成电流与非换相相电流之间的关系式,通过控制所需合... 具有非换相相电流反馈的无刷直流电机的传统双闭环调速系统,因非理想梯形波反电势和非理想方波相电流存在较大转矩脉动,该文引入正比于瞬时转矩的合成电流变量,并推导出每个扇区下的合成电流与非换相相电流之间的关系式,通过控制所需合成电流的对应非换相相电流,达到抑制转矩脉动的目的。此外,为了减小换相转矩脉动,采用一种基于PWM-on的新型调制方式。该调制方式在换相期间,三相将进行配合调制,通过计算给每一相分配不同的调制占空比,使开通相和关断相的电流变化率相等。所提转矩脉动抑制方法通过相应的Matlab仿真和数字信号处理驱动实验,验证了其可行性和有效性。 展开更多
关键词 无刷直流电机 合成电流控制 双闭环调速系统 转矩脉动抑制 配合调制
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Substituent groups from aromatic dicarboxylates modulated structural diversification in the assembly of Co(Ⅱ)complexes based on the bis-pyridyl-bis-amide ligands 被引量:2
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作者 WANG XiuLi MU Bao +4 位作者 LIN HongYan YANG Song LIU GuoCheng TIAN AiXiang ZHANG JuWen 《Science China Chemistry》 SCIE EI CAS 2013年第5期557-566,共10页
Four coordination polymers based on two bis-pyridyl-bis-amide ligands and three aromatic dicarboxylates with different substituent groups, namely, [Co(3-bpcb)x.5(NPH)(H20)]" 4H20 (1), [Co(3-bpcb)(NIPH)] ... Four coordination polymers based on two bis-pyridyl-bis-amide ligands and three aromatic dicarboxylates with different substituent groups, namely, [Co(3-bpcb)x.5(NPH)(H20)]" 4H20 (1), [Co(3-bpcb)(NIPH)] (2), [Co(3-bpcb)0.5(5-H2AIP)]" 2H20 (3), [Co(3-bpcd)0.5(5-H2AIP)(H20)]" 2H20 (4) [3-bpcb = N,N'-bis(3-pyridinecarboxamide)-l,4-benzene, 3-bpcd = N,N'-bis(3- pyridine)cyclohexane-l,4-dicarboxamide, H2NPH = 3-nitrophthalic acid, H2NIPH = 5-nitroisophthalic acid, 5-HaAIP = 5-aminoisophthalic acid] have been synthetized under hydrothermal conditions. Complex 1 displays a one dimensional (1D) chain based on the binuclear [Co2(NPH)2] units and 3-bpeb ligands, which is extended into a three dimensional (3D) supra- molecular framework through hydrogen bonding and n-n stacking interactions. In complex 2, the (3,5)-connected two dimen- sional (2D) layers are constructed from 1D Co-NIPH chains and bidentate-bridging 3-bpeb ligands. Complex 3 is a 2D double layer based on Co-5-H2AIP 2D layers and 3-bpeb pillars. Complex 4 also displays a 2D network, which is constructed from the Co-5-H2AIP 1D double chains and 3-bpcd ligands. Finally, complexes 2--4 are extended into 3D supramolecular frame- works by hydrogen bonding or n-re stacking interactions. The substituent groups of dicarboxylates play an important role in the assembly and structures of the title complexes. In addition, the fluorescent properties of complexes 1-4 and the electrochemi- cal behaviors of 3 and 4 at room temperature have been investigated. 展开更多
关键词 coordination polymer bis-pyridyl-bis-amide ligand hydrothermal reaction fluorescent property
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Fabrication of ZnO with tunable morphology through a facile treatment of Zn-based coordination polymers
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作者 Panpan Su Jiao Zhao +2 位作者 Feng Rong Can Li Qihua Yang 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第3期411-416,共6页
The morphology and structure of zinc oxide(ZnO), one of the important semiconductors, are relevant to its properties and applications. The preparation of ZnO with tunable morphology and desired structure is an attract... The morphology and structure of zinc oxide(ZnO), one of the important semiconductors, are relevant to its properties and applications. The preparation of ZnO with tunable morphology and desired structure is an attractive topic in the field of material synthesis. This work reports a facile method for the synthesis of Zn O with controllable morphology and crystal orientation using Zn-based coordination polymer particles(Zn-CPP) as precursors. Using hydrothermal method, Zn-CPP with morphologies of microrod, nanoplate, flower-like, arrow-tipped microsheet, and square cylinder were successfully synthesized via the coordination between metal ions Zn2+ and organic ligand 1,4,5,8-naphthalenetetracarboxylic dianhydride in aqueous solution. Subsequent thermal treatment of the Zn-CPP successfully resulted in the formation of porous Zn O with similar morphology to Zn-CPP. It is also found that the Zn O with enhanced(002) orientation could be obtained from Zn-CPP with preferred(002) orientation. This strategy could be extended for the preparation of other metal oxides with desired shape and structure. 展开更多
关键词 ZNO coordination polymers hydrothermal method micro and nanostructure specific morphology
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