The utilization of position sensor reduces the system reliability of switched reluctance motor(SRM),especially in harsh environments.It also increases the complexity of the system.Therefore,the research on sensorless ...The utilization of position sensor reduces the system reliability of switched reluctance motor(SRM),especially in harsh environments.It also increases the complexity of the system.Therefore,the research on sensorless control has become one of the hot spots in recent years.Comparing with the existing sensorless control technology,the new method exploring the sensorless control of double-sided linear switched reluctance motor(DLSRM)shows the following advantages:1)high accuracy,and 2)good practicability.Based on the new proposed method,the DLSRM speed controller is augmented with the peak current method and the voltage chopping closed-loop speed control.Moreover,the winding resistance in the equation is corrected according to the integral flux linkage when the phase current is zero.The accuracy and feasibility of the simplified flux linkage method in estimating the position of the DLSRM is verified.展开更多
This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil dat...This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil data groups were used in this study. The relative drainage rate, which is a unique parameter and independent of the soil type in the simplified dynamic method, was analyzed using the pressure-based method with a matric potential of -1/3 bar and the flux-based method with a drainage flux of 0.005 cm/d. As a result, the relative drainage rate of the simplified dynamic method was determined to be 3% per day. This was verified by the similar field capacity results estimated with the three methods for most soils suitable for cultivating plants. In addition, the drainage time calculated with the simplified dynamic method was two to three days, which agrees with the classical definition of field capacity. We recommend the simplified dynamic method with a relative drainage rate of 3% per day due to its simple application and clearly physically-based concept.展开更多
This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machin...This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.展开更多
可变磁阻旋转变压器由于其耐高温、受机械振动影响小、结构简单等优点广泛应用于恶劣工作环境的转子位置检测。此前工作提出了一种内定子变磁阻旋转变压器径向集成在永磁同步电机中的混合双定子电机结构,并采用改进绕组函数法(Modified ...可变磁阻旋转变压器由于其耐高温、受机械振动影响小、结构简单等优点广泛应用于恶劣工作环境的转子位置检测。此前工作提出了一种内定子变磁阻旋转变压器径向集成在永磁同步电机中的混合双定子电机结构,并采用改进绕组函数法(Modified winding function approach,MWFA)对其磁场分布和电磁参数进行解析分析。然而,解析计算得到的气隙磁通密度在槽开口处与有限元分析结果相比仍存在偏差。为此,提出分段绕组函数法(Segmented winding function method,SWFM),通过考虑磁场和绕组的实际分布,对气隙和线圈匝数函数进行分段处理,进一步提高解析计算结果的精确性。利用该方法计算气隙磁通密度和励磁绕组自感,并将SWFM和MWFA结果与有限元分析进行对比,验证所提方法的有效性。展开更多
局部简化建模法即在不影响计算结果精度的要求下,在对实物进行建模时适当地做一些简化处理,对所关心的部件进行精细建模,而对其余部件进行简化建模。为验证局部简化建模法的有效性,文中基于TEAM Problem 21基准族中的P21~a-2,P21~0-B模...局部简化建模法即在不影响计算结果精度的要求下,在对实物进行建模时适当地做一些简化处理,对所关心的部件进行精细建模,而对其余部件进行简化建模。为验证局部简化建模法的有效性,文中基于TEAM Problem 21基准族中的P21~a-2,P21~0-B模型,进行了详细地实验研究与仿真分析。重点考察了不同激励下采用局部简化建模法对变压器结构件(如变压器油箱)中杂散损耗、漏磁通密度计算值与测量值之间的对应关系。计算值与测量值具有较好的一致性,从而验证了局部简化建模法的工程适用性。在计算机资源有限的情况下,如何对装置模型进行简化计算是科学工作者致力于研究的一项重大内容。局部简化建模法对大型电力变压器电磁热模拟的合理建模,高效的仿真计算具有重要的意义。展开更多
对比分析了常用的建筑物能耗分析方法,提出改良温频法(Modified BIN Method),经过改进并按我国情况取定一些参数后,适于我国应用。本项目在大量统计研究基础上,对日射负荷修正系数等重要参数作了改进,并用改进后的算法和参数进行了实例...对比分析了常用的建筑物能耗分析方法,提出改良温频法(Modified BIN Method),经过改进并按我国情况取定一些参数后,适于我国应用。本项目在大量统计研究基础上,对日射负荷修正系数等重要参数作了改进,并用改进后的算法和参数进行了实例计算,与实测结果相对照是令人满意的。展开更多
文摘The utilization of position sensor reduces the system reliability of switched reluctance motor(SRM),especially in harsh environments.It also increases the complexity of the system.Therefore,the research on sensorless control has become one of the hot spots in recent years.Comparing with the existing sensorless control technology,the new method exploring the sensorless control of double-sided linear switched reluctance motor(DLSRM)shows the following advantages:1)high accuracy,and 2)good practicability.Based on the new proposed method,the DLSRM speed controller is augmented with the peak current method and the voltage chopping closed-loop speed control.Moreover,the winding resistance in the equation is corrected according to the integral flux linkage when the phase current is zero.The accuracy and feasibility of the simplified flux linkage method in estimating the position of the DLSRM is verified.
基金supported by the National Natural Science Foundation of China(Grants No.51179083 and 91225302)
文摘This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey （BC） model and the van Genuchten （vG） model, and four soil data groups were used in this study. The relative drainage rate, which is a unique parameter and independent of the soil type in the simplified dynamic method, was analyzed using the pressure-based method with a matric potential of -1/3 bar and the flux-based method with a drainage flux of 0.005 cm/d. As a result, the relative drainage rate of the simplified dynamic method was determined to be 3% per day. This was verified by the similar field capacity results estimated with the three methods for most soils suitable for cultivating plants. In addition, the drainage time calculated with the simplified dynamic method was two to three days, which agrees with the classical definition of field capacity. We recommend the simplified dynamic method with a relative drainage rate of 3% per day due to its simple application and clearly physically-based concept.
基金Project (No. 50677060) supported by the National Natural ScienceFoundation of China
文摘This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.
文摘可变磁阻旋转变压器由于其耐高温、受机械振动影响小、结构简单等优点广泛应用于恶劣工作环境的转子位置检测。此前工作提出了一种内定子变磁阻旋转变压器径向集成在永磁同步电机中的混合双定子电机结构,并采用改进绕组函数法(Modified winding function approach,MWFA)对其磁场分布和电磁参数进行解析分析。然而,解析计算得到的气隙磁通密度在槽开口处与有限元分析结果相比仍存在偏差。为此,提出分段绕组函数法(Segmented winding function method,SWFM),通过考虑磁场和绕组的实际分布,对气隙和线圈匝数函数进行分段处理,进一步提高解析计算结果的精确性。利用该方法计算气隙磁通密度和励磁绕组自感,并将SWFM和MWFA结果与有限元分析进行对比,验证所提方法的有效性。
文摘局部简化建模法即在不影响计算结果精度的要求下,在对实物进行建模时适当地做一些简化处理,对所关心的部件进行精细建模,而对其余部件进行简化建模。为验证局部简化建模法的有效性,文中基于TEAM Problem 21基准族中的P21~a-2,P21~0-B模型,进行了详细地实验研究与仿真分析。重点考察了不同激励下采用局部简化建模法对变压器结构件(如变压器油箱)中杂散损耗、漏磁通密度计算值与测量值之间的对应关系。计算值与测量值具有较好的一致性,从而验证了局部简化建模法的工程适用性。在计算机资源有限的情况下,如何对装置模型进行简化计算是科学工作者致力于研究的一项重大内容。局部简化建模法对大型电力变压器电磁热模拟的合理建模,高效的仿真计算具有重要的意义。
