The paper deals with a new model of linear induction motor (LIM) to improve the reliability of the system. Based on the normal equation circuit of LIM considering the dynamic end effect, an equivalent circuit model wi...The paper deals with a new model of linear induction motor (LIM) to improve the reliability of the system. Based on the normal equation circuit of LIM considering the dynamic end effect, an equivalent circuit model with compensation of large end effect is constructed when the end effect force at synchronism is of braking character. The equivalent circuit model is used for secondary-flux oriented control of LIM. Single neuron network PI unit for LIM servo-drive is also discussed. The effectiveness of mathematical model for drive control is verified by simulations.展开更多
Because of the end effect, a linear induction motor （LIM） runs in an asymmetrical state even though the winding of each phase is symmetric. Based on the basic principle of the LIM, a new approach was proposed to cal...Because of the end effect, a linear induction motor （LIM） runs in an asymmetrical state even though the winding of each phase is symmetric. Based on the basic principle of the LIM, a new approach was proposed to calculate the thrust of the LIM using the instantaneous current value. A three-phase LIM model with 12 slots and a singlelayer winding was designed to validate this method. The experiments show that when the current is small, the calculated results basically agree with the experiments. The agreement becomes worse with the increase of the current because of the saturation of the primary iron core. The proposed formula is suitable when the iron core of the LIM primary is in an unsaturated state.展开更多
The characteristics of linear transformer are studied analytically. The transformer is composed in one of modes of linear motor-transformer apparatus proposed for future wireless light rail vehicle (LRV). The secondar...The characteristics of linear transformer are studied analytically. The transformer is composed in one of modes of linear motor-transformer apparatus proposed for future wireless light rail vehicle (LRV). The secondary (onboard) power factor can be adjusted at any value by an onboard converter. The equivalent circuit is used to study the transferred power control. The parameters are determined by three-dimensional finite element method (FEM) analysis for one pole-pair model. Under the rated primary (input) and secondary voltage and current, which are specified for linear motor operation, the characteristics of the secondary power factor are cleared. It is also shown that the input capacitor can improve the primary power factor and decrease the input power capacity, but does not change the efficiency. This linear transformer has the efficiency of 91% and the input power factor of 0.87 when the apparatus without input capacitor is controlled at the secondary power factor of 0.4.展开更多
直线电机边端效应是由定子铁心、次级开断所致的固有效应,该效应会引起电机电磁推力的不同频率的脉动。本文首先基于电磁推力公式对边端效应所致的推力脉动频率进行了理论分析。然后利用一维磁路法对动态纵向边端效应引起的次级感应涡...直线电机边端效应是由定子铁心、次级开断所致的固有效应,该效应会引起电机电磁推力的不同频率的脉动。本文首先基于电磁推力公式对边端效应所致的推力脉动频率进行了理论分析。然后利用一维磁路法对动态纵向边端效应引起的次级感应涡流沿轴向的分布规律进行了理论分析和解析计算,根据次级感应涡流进而计算得到了动态纵向边端效应引起的转差频率两倍频推力脉动幅值的解析表达式,并得到了推力脉动幅值和不考虑边端效应时的电磁推力值的比例关系,最后通过峰值功率20 MW,最大出力900 k N的大功率直线感应电动机实验系统对分析结论进行了试验验证。理论分析和试验结果表明:计及边端效应时直线电机电磁推力存在供电频率两倍频和转差频率两倍频的脉动,其中转差频率两倍频的脉动由动态纵向边端效应导致,主要和次级极数以及转差频率有关。展开更多
长初级双边直线感应电机(double-sided linear induction motor,DSLIM)制动时短次级作用区域与未作用区域的气隙磁场不同,造成的纵向动态边端效应对电机制动性能产生一定影响。该文建立长初级DSLIM解析模型,在考虑电机横向边端效应与纵...长初级双边直线感应电机(double-sided linear induction motor,DSLIM)制动时短次级作用区域与未作用区域的气隙磁场不同,造成的纵向动态边端效应对电机制动性能产生一定影响。该文建立长初级DSLIM解析模型,在考虑电机横向边端效应与纵向动态边端效应的基础上,推导长初级DSLIM回馈制动与直流能耗制动时气隙磁密和制动力解析公式,分析长初级DSLIM随滑差率、品质因数、次级速度、次级电阻等参数变化下的制动特性,定量分析纵向动态边端效应对回馈制动与直流能耗制动的不同影响。研究显示电机回馈制动时的纵向动态边端效应在滑差率接近零时变小,直流能耗制动时的纵向动态边端效应在最大制动力时最强,通过增加次级作用区域极数和电机低滑差率制动能有效抑制纵向动态边端效应。建立了一台实验样机三维有限元模型,进行了仿真与实验,结果验证了长初级DSLIM制动特性计算方法的准确性与实用性。展开更多
由于直接转矩控制策略对定子磁链和电磁转矩采取非线性滞环控制,电机的电磁转矩、磁链幅值、相电流存在稳态误差。该文提出基于空间矢量调制的异步电机直接转差线性控制策略(direct slip linear control based on space vector modulati...由于直接转矩控制策略对定子磁链和电磁转矩采取非线性滞环控制,电机的电磁转矩、磁链幅值、相电流存在稳态误差。该文提出基于空间矢量调制的异步电机直接转差线性控制策略(direct slip linear control based on space vector modulation,DSLC-SVM)。该策略不含坐标变换,无电流环,只需辨识定子磁链。与传统直接转矩控制策略相比,由于对转差进行直接线性控制,DSLC-SVM策略可以减小转矩和磁链误差,降低相电流的总谐波失真(total harmonic distortion,THD)。比较了2种控制策略改变转差的能力,通过对比实验,验证了该文所提算法的正确性和可行性。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 50477030) the Natural Science Foundation of Zheji-ang Province (No. Y105351), China
文摘The paper deals with a new model of linear induction motor (LIM) to improve the reliability of the system. Based on the normal equation circuit of LIM considering the dynamic end effect, an equivalent circuit model with compensation of large end effect is constructed when the end effect force at synchronism is of braking character. The equivalent circuit model is used for secondary-flux oriented control of LIM. Single neuron network PI unit for LIM servo-drive is also discussed. The effectiveness of mathematical model for drive control is verified by simulations.
基金supported by the National Natural Science Foundation of China (Nos. 50588201,50672078, and 50872116)the National Basic Research Program (973 program, No. 2007CB616906)+1 种基金the Australian Research Council (Grant No. DP0559872 and DP0881739)the PCSIRT of the Ministry of Education of China (No. IRT0751)
文摘Because of the end effect, a linear induction motor （LIM） runs in an asymmetrical state even though the winding of each phase is symmetric. Based on the basic principle of the LIM, a new approach was proposed to calculate the thrust of the LIM using the instantaneous current value. A three-phase LIM model with 12 slots and a singlelayer winding was designed to validate this method. The experiments show that when the current is small, the calculated results basically agree with the experiments. The agreement becomes worse with the increase of the current because of the saturation of the primary iron core. The proposed formula is suitable when the iron core of the LIM primary is in an unsaturated state.
文摘The characteristics of linear transformer are studied analytically. The transformer is composed in one of modes of linear motor-transformer apparatus proposed for future wireless light rail vehicle (LRV). The secondary (onboard) power factor can be adjusted at any value by an onboard converter. The equivalent circuit is used to study the transferred power control. The parameters are determined by three-dimensional finite element method (FEM) analysis for one pole-pair model. Under the rated primary (input) and secondary voltage and current, which are specified for linear motor operation, the characteristics of the secondary power factor are cleared. It is also shown that the input capacitor can improve the primary power factor and decrease the input power capacity, but does not change the efficiency. This linear transformer has the efficiency of 91% and the input power factor of 0.87 when the apparatus without input capacitor is controlled at the secondary power factor of 0.4.
文摘直线电机边端效应是由定子铁心、次级开断所致的固有效应,该效应会引起电机电磁推力的不同频率的脉动。本文首先基于电磁推力公式对边端效应所致的推力脉动频率进行了理论分析。然后利用一维磁路法对动态纵向边端效应引起的次级感应涡流沿轴向的分布规律进行了理论分析和解析计算,根据次级感应涡流进而计算得到了动态纵向边端效应引起的转差频率两倍频推力脉动幅值的解析表达式,并得到了推力脉动幅值和不考虑边端效应时的电磁推力值的比例关系,最后通过峰值功率20 MW,最大出力900 k N的大功率直线感应电动机实验系统对分析结论进行了试验验证。理论分析和试验结果表明:计及边端效应时直线电机电磁推力存在供电频率两倍频和转差频率两倍频的脉动,其中转差频率两倍频的脉动由动态纵向边端效应导致,主要和次级极数以及转差频率有关。
文摘长初级双边直线感应电机(double-sided linear induction motor,DSLIM)制动时短次级作用区域与未作用区域的气隙磁场不同,造成的纵向动态边端效应对电机制动性能产生一定影响。该文建立长初级DSLIM解析模型,在考虑电机横向边端效应与纵向动态边端效应的基础上,推导长初级DSLIM回馈制动与直流能耗制动时气隙磁密和制动力解析公式,分析长初级DSLIM随滑差率、品质因数、次级速度、次级电阻等参数变化下的制动特性,定量分析纵向动态边端效应对回馈制动与直流能耗制动的不同影响。研究显示电机回馈制动时的纵向动态边端效应在滑差率接近零时变小,直流能耗制动时的纵向动态边端效应在最大制动力时最强,通过增加次级作用区域极数和电机低滑差率制动能有效抑制纵向动态边端效应。建立了一台实验样机三维有限元模型,进行了仿真与实验,结果验证了长初级DSLIM制动特性计算方法的准确性与实用性。
文摘由于直接转矩控制策略对定子磁链和电磁转矩采取非线性滞环控制,电机的电磁转矩、磁链幅值、相电流存在稳态误差。该文提出基于空间矢量调制的异步电机直接转差线性控制策略(direct slip linear control based on space vector modulation,DSLC-SVM)。该策略不含坐标变换,无电流环,只需辨识定子磁链。与传统直接转矩控制策略相比,由于对转差进行直接线性控制,DSLC-SVM策略可以减小转矩和磁链误差,降低相电流的总谐波失真(total harmonic distortion,THD)。比较了2种控制策略改变转差的能力,通过对比实验,验证了该文所提算法的正确性和可行性。
