笼型转子无刷双馈电机等效电路及电磁转矩

无刷双馈电机是一种性能优良的新型感应电机。经过频率和绕组归算得出笼形转子无刷双馈电机的通用等效电路。等效电路对电动状态和发电状态都适用。在此基础上，得出了双馈电机在自然同步和异步特殊运行模式下的等效电路，然后根据等效电路得出了电磁转矩计算公式。它利用了最新的笼形转子无出线电流检测技术。     

无刷双馈电机的效率分析

无刷双馈电机是一种新型的感应电机,可以降低调速系统的容量,对电网的谐波污染小,因而具有很好的发展前景.从无刷双馈电机的原理出发,分析了定子和转子的损耗,进一步对定子绕组极数的选择、定子绕组的设计形式、转子绕组极数的选择以及转子绕组的设计等方面进行了详尽的说明和分析,总结出提高该类电机效率的方法和途径.     

绕线转子无刷双馈电机‘Π’型等效电路

等效电路是电机性能分析的重要工具。由于无刷双馈电机为多耦合系统,传统等效电路计算复杂,该文提出了无刷双馈电机更简洁的‘Π’型等效电路,为这种电机的性能分析提供了简单有效的方法。首先根据感应电机基本原理,引出了无刷双馈电机的基本等效电路,考虑无刷双馈电机具体适用工况,将基本等效电路参数均折算到控制绕组。然后,在控制绕组为参考的等效电路基础上,通过电路等效,导出无刷双馈电机的‘Π’型等效电路。进一步对绕线转子无刷双馈电机等效电路的参数获得进行研究,讨论了使用解析法需要注意的地方;并提出用试验直接测定无刷双馈电机基本电路参数的办法。最后,在60k W绕线转子无刷双馈电机样机平台上进行试验,试验结果验证了‘Π’型等效电路的有效性,及参数计算、测试方法的正确性。     

磁阻式无刷双馈电机的转子结构及其性能分析

把磁阻式结构与绕线式转子结构相结合,提出一种具有磁阻式无刷双馈电机的转子结构。该转子结构既保持了绕线式转子绕线接线方式的灵活性,又发挥了磁阻式转子对磁通的导向作用,改善了电机的磁场调制效果,可以很好地实现转子与定子两套绕组耦合能力实现最大化。对磁阻式转子结构的无刷双馈电机的设计原理和方法进行了详细分析,以一台30k W样机为例说明了磁阻式无刷双馈电机的功率分配曲线、气隙磁通密度曲线和电机效率,并与磁障结构的磁阻式、加入笼条的磁阻式转子无刷双馈电机在同等条件下的电机输出功率作对比。最后对无刷双馈发电系统的动态特性进行样机实验,实验结果表明采用该方法设计的磁阻式无刷双馈电机具有优良的性能。     

笼型转子无刷双馈电机等效电路的分析及应用

无刷双馈电机作为一种新型交流电机,在电动机变频调速控制以及发电机变速恒频控制领域具有广阔的应用前景,然而其结构、电磁关系、运行特性都比常规电机更加复杂。为了研究该电机的运行特性,本文从笼型转子结构的无刷双馈电机基本电磁关系出发,运用电机学的基本理论和方法,推导了其的电压基本方程,经过频率归算和绕组归算,得到笼型转子无刷双馈电机的通用等效电路和相量图,进而得到了该电机在自然同步和异步运行模式下的等效电路。在此基础上,利用VB编程进行了该电机的电磁设计,通过计算得到了等效电路中的各个参数值,并利用Matlab对该电机不同运行模式下的运行性能进行了仿真分析,说明了等效电路及其参数值的正确性。     

无刷双馈调速电机的参数计算

本文对无刷双馈调速电机的定转子绕组参数进行了分析和计算,将转子绕组折算成三相,结合无刷双馈电机的等效电路,可以对无刷调速电机的稳态运行性能进行分析和计算,为该类电机设计计算提供了有力的理论工具。     

磁障转子无刷双馈电机运行特性及实验研究

针对普通凸极磁阻转子无刷双馈电机的转子耦合能力差、效率低的问题,提出一种结构简单、性能良好的磁障转子结构,设计了额定功率为5kW、6/2极的转子带磁障的无刷双馈磁阻电机,运用有限元法分析了转子带磁障无刷双馈磁阻电机的电动和发电运行特性,在此基础上,对转子带磁障的无刷双馈电机进行了变速恒频发电的开环实验。理论分析和实验研究结果表明:适当在转子铁心中加入磁障,可以有效改善转子带磁障的无刷双馈磁阻电机的性能,同时又保留普通凸极磁阻转子结构简单和成本低廉的优点,为今后设计大功率磁障转子无刷双馈磁阻电机提供有价值的参考依据。     

磁障转子无刷双馈电机

为了研究在转子铁心中引入磁障对磁阻转子无刷双馈电机性能的影响,基于场路耦合有限元分析,对比研究了转子极弧系数与磁障数量及结构参数对无刷双馈磁阻电机性能的影响,并在此基础上,提出了一种结构简单、性能较好的无刷双馈磁障转子设计方案。通过样机实验,验证了该磁障转子无刷双馈电机的设计方法及其双馈运行特性。理论分析和实验研究结果表明:在电机结构尺寸相同情况下,通过在转子铁心中适当引入磁障,可以有效地改善磁阻转子无刷双馈电机的性能,并使其保留普通磁阻转子结构简单和成本低廉的优点。     

不同转子结构无刷双馈电机稳态运行特性的对比实验研究

笼型和磁阻转子是无刷双馈电机常用的两种转子结构型式，为了对比研究不同转子结构对该种电机稳态运行特性的影响，研制了具有同一定子和两个不同结构转子的实验样机，并进行了对比实验研究。实验结果表明，各向异性轴向叠片的ALA（Axially Laminated Anisotropic）磁阻转子无刷双馈电机具有较好的同步和双馈调速特性，而笼型转子无刷双馈电机具有较好的起动和异步运行特性。     

无刷双馈电机转差率问题探讨：

无刷双馈电机数学模型的推导、相量图和等效电路的绘制，都需通过转差率进行绕组间的频率折算。无刷双馈电机中共有三个转差率：①转子绕组对定子功率绕组旋转磁场的转差率％，②转子绕组对定子控制绕组旋转磁场的转差率sc，③定子控制绕组旋转磁场对定子功率绕组旋转磁场的转差率s。这些转差率的计算方法在众多文献中的阐述与推导均令人费解，物理意义不甚明了。文章首先从普通异步电机出发，推导并给出了无刷双馈电机三个转差率的明确定义和简单计算方法。     

The brushless doubly fed reluctance machine and the synchronousreluctance machine-a comparison

The brushless doubly fed reluctance machine (BDFRM) is related to the better known brushless doubly fed induction machine (BDFIM). Research into doubly fed machines is motivated by the fact that they allow the use of a partially rated inverter in many variable-speed applications. Research into the BDFRM has been largely ignored in comparison to the BDFIM, despite the fact that it has the potential for greater efficiency as compared to the BDFIM, and the rotor is simpler to manufacture. This paper compares the BDFRM and its singly fed cousin, the synchronous reluctance machine. This is a natural comparison since both machines use the same reluctance rotor. The first part of the paper establishes relationships between the inductances of the two machines. This is then used to facilitate a comparison using the constraints that both machines have the same amount of active material, i.e., the same amount of copper and iron, and that the copper losses for both machines are the same. This analysis also allows an approximate comparison with the conventional squirrel-cage induction machine. The analysis is carried out using machine-independent normalizations     

磁阻和笼型转子无刷双馈电机的统一等效电路和转矩公式

无刷双馈电机是一种适用于变频调速系统使用的新型电机、其结构型式和工作原理与传统交流电机相比具有较大差异。文中采用传统的电机分析方法,分别建立了具有不同转子结构型式无刷双馈电机的数学模型,导出了其等效电路和电磁转矩相同的表达式,并对等效电路中的电感参数进行了实验验证。     

无刷双馈电机的稳态转矩-角特性

简述了从无刷双馈电机的电机变量的方程推导无刷双馈电机的双轴数学模型,在双轴模型的基础上,仿真研究了稳态运行时ｄ－ｑ模型下功率绕组与控制绕组间电压相角差与电机电磁转矩的关系,揭示了无刷双馈电机稳态运行时具有同步电机特性,并为该电机运行状态的控制提供了依据。     

Design and performance analysis of a 700‐kW wound‐rotor BDFIG for ship shaft generator application

In this paper, a 700‐kW brushless doubly fed induction generator (BDFIG) is designed for stand‐alone ship shaft generator application. Based on the principle of tooth harmonics and sinusoidal winding structure, a multi‐pitch unequal‐turn‐coil wound rotor is adopted to reduce harmonic contents and couple the two stator windings effectively. The performance analyses of a prototype BDFIG with two/four pole pairs are presented. The magnetic fields, air‐gap flux densities, and current densities with full load at different shaft speeds of the prototype machine are investigated. Simulation analysis and experimental tests verify that the output capability and the efficiency of the prototype machine could meet the design requirements of a 700‐kW generator and that the wound rotor structure is suitable for high‐power brushless doubly fed machines. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

The use of doubly fed reluctance machines for large pumps and wind turbines

Brushless doubly fed induction machines (BDFIMs) have been extensively researched over because of the possibility of using a partially rated inverter in many applications with limited speed variations. However, the special cage rotor construction and substantial rotor losses is one of the key deficiencies of these machines. A similar and extremely interesting machine, the brushless doubly fed reluctance machine (BDFRM), has been largely ignored in comparison. This was mainly due to the fact that reluctance rotor designs were not capable of generating saliency ratios large enough to make the BDFRM competitive with other machines. However, developments in reluctance rotors, spurred on by research into synchronous reluctance machines, have resulted in high-saliency-ratio cageless rotors that are economical to build. This, together with the promise of higher efficiency and simpler control compared to the BDFIM, means that further investigation of the BDFRM is warranted. This paper presents a comparative theoretical analysis and aspects of practical implementation of the important control strategies and associated machine performance/inverter size tradeoffs for the BDFRM in the light of its most likely applications-large-pump-type adjustable-speed drives and variable-speed constant-frequency wind power generation systems.     

Encoderless direct torque controller for limited speed range applications of brushless doubly fed reluctance motors

The paper proposes a direct torque control (DTC) algorithm suitable for low-variable-frequency operation of the brushless doubly fed reluctance machine (BDFRM) and considers aspects of its practical implementation. The simulation and experimental results show that a small BDFRM prototype can successfully operate down to zero supply frequency of the inverter-fed (secondary) winding, unlike cage induction or many other alternating current machines with DTC. This BDFRM advantage is a consequence of using a flux estimation technique not relying on the secondary voltage integration and therefore avoiding the well-known problems at low secondary frequencies, being typical for the BDFRM normal operation. The developed algorithm also offers the prospect for optimizing the machine performance in a manner similar to conventional vector controllers but with control actions executed in a stationary reference frame as usual for all traditional DTC methods. The maximum torque per inverter ampere control strategy has been chosen as a case study.     

Steady-state performance of a line-start synchronous reluctance motor with capacitive assistance

This paper sets forth the steady-state performance analysis of a connection scheme that improves the power factor and torque with a lower magnetizing current for a line-start synchronous reluctance motor. The machine stator winding is split into two equal halves, one connected to the mains and the other connected to a balanced capacitor. Performance of the machine is improved if the capacitor value is such that the winding to which it connected operate at or very close to resonance in the d-axis. Current in both windings contributes positively to torque production and external control circuitry is not required. Steady-state equations arising from the d–q model gives a direct insight on the operating limits and how this capacitance aids the machines torque and power factor by boosting its direct axis reactance while the quadrature axis reactance remains fairly constant. An equivalent circuit is also deduced from the steady-state equations from which an explicit expression for input impedance of the new machine can be derived. Conditions for unity-power factor at varying load conditions are also examined. A comparison with conventional single-winding synchronous reluctance motor is given. Such comparison is fair because both machines have the same amount of copper and iron. Experimental results are provided to validate the analytical results.     

Synchronous drive performance of brushless doubly-fed motors

This paper presents studies of the steady-state performance of the brushless doubly-fed machine for adjustable-speed drive applications. The equivalent circuit and basic performance equations are presented followed by a proven technique for the solution of the least restrained form of the equations. Model predictions and experimental results are given. The studies show that the machine acts like both a synchronous motor, with power factor adjustable by control winding excitation, and a slip-ring induction machine with slip power recovery and a low converter rating. The model is suitable for development of control schemes and performance index optimization     

转子极数对无刷双馈电机耦合能力的影响

针对目前无刷双馈电机(BDFM)两套不同极数定子绕组之间,耦合能力弱而导致该类型电机功率密度低及性能指标差的问题,以结构简单易于制造的普通凸极磁阻转子BDFM为例,研究了转子极数对电机耦合能力的影响。基于绕组函数理论,对BDFM进行了电感参数计算;通过分析电感参数,研究了极数、相同转子极数而不同定子绕组的极数配合和多极凸极磁阻转子对其耦合的影响。研究表明:合适的转子极数和极数配合可以改进BDFM的耦合能力,进而提高其功率密度,改善其性能指标。     

Analysis of a polyphase synchronous reluctance motor with two identical stator windings

This paper presents the performance analysis of a cageless two-stator-winding reluctance motor which is capable of developing reluctance torque at good power factors in the absence of inverter control. The machine stator has two separate identical polyphase windings whose pole numbers are the same as that of the cageless rotor. The machine performance is investigated using the traditional circle diagrams, and the d–q rotor reference frame equations derived in space-vector form by applying the concept of winding functions. Core loss and saturation are accounted for in the developed dynamic model. It is shown that if one winding is connected directly to the supply and the other fed with a balanced capacitor, the developed torque is superior to a brushless doubly-fed reluctance machine (BDFRM) of similar size. Other motor characteristics, its line-start behaviour and torque ripples are also presented and discussed. Experimental results corroborate the simulations.