转子磁分路式径向结构混合励磁同步发电机的空载特性

转子磁分路径向结构混合励磁同步电机利用磁分路结构可以方便地调节电机的气隙磁场。本文描述了电机的结构和原理,研究了该电机的空载特性,针对空载电动势调节范围较小的问题,探讨了减小电机导磁体间的漏磁、提高气隙磁通密度的方法,并讨论了永磁部分长度、电励磁部分长度对电机空载特性的影响。仿真和实验结果表明:磁分路径向结构混合励磁同步发电机适宜短而粗的结构,其轴向长度的变化对电机的空载特性影响很大。     

RTDS中同步电机模型特性研究

首先对RTDS中同步电机建模问题进行一般性的分析。然后在此基础上,采用典型同步电机参数,应用RTDS中的同步电机模型进行电机静态特性和动态特性实验,包括空载和稳态短路实验,以及突然三相短路实验。通过实验结果进行分析验证了RTDS中同步发电机模型的正确性。     

RTDS中同步电机模型特性研究

首先对RTDS中同步电机建模问题进行一般性的分析.然后在此基础上,采用典型同步电机参数,应用RTDS中的同步电机模型进行电机静态特性和动态特性实验,包括空载和稳态短路实验,以及突然三相短路实验.通过实验结果进行分析验证了RTDS中同步发电机模型的正确性.     

电机空载损耗的试验分离法

对于直流电机和同步电机而言,当磁极没有励磁时,空载损耗就为机械损耗,而当磁极有励磁时,空载损耗则为铁心损耗与机械损耗之和。据此,可以通过空载试验将电机的铁心损耗与机械损耗相分离。试验线路如下: 图中D为电动机,F为被试电机。调节R_D使被试电机F达额定转速,调节R_F使被试电机F的空载电压为额定电压,再调节R_D使被试电机转速增至1.25倍的额     

并列结构混合励磁无刷同步发电机的原理及实现

针对永磁同步发电机磁场调节困难、输出电压不可调等问题,研制了一种新型并列结构混合励磁同步发电机,阐述丁它的结构及调磁原理,分析了它的等效磁路,并通过对原理样机的试验测试了其空载特性、外特性及调节特性.结果显示:并列结构混合励磁无刷同步电机结构可行,解决了永磁同步电机的缺陷.     

同步电机二维电磁场仿真分析

在当前“双碳”目标的发展趋势下,新能源汽车日益增多。因此,提升电机效率、降低电机损耗成为同步电机的主要发展方向。本文首先介绍同步电机的结构和电磁参数。其次,根据实际情况建立同步电机二维模型,并通过Maxwell软件对所建模型进行稳态电磁仿真实验,分析发电机的磁路走向、磁通密度和磁场强度。最后,基于电磁场理论,将麦克斯韦方程作为控制方程及边际条件,通过有限元法对同步电机进行电磁分析。通过添加时间步进行瞬态电磁场仿真实验,仿真负载电机输出功率与转矩,计算损耗和效率,分析在启动和空载下,电机内部磁场的分布和变化规律。     

新型双定子混合励磁风力发电机三维有限元分析及实验研究

提出一种新型双定子混合励磁风力发电机,分析电机的结构特点及工作原理,计算电机的空载磁场分布、静态特性及空载特性,并对样机进行实验研究。基于三维有限元方法,采用ANSYS软件计算了电机的空载磁场分布,得到了空载内外定子电枢绕组磁链、内外定子电动势及合成电动势;根据磁链法分别计算了电枢绕组和励磁绕组电感等参数;分析了电机额定转速400 r/min时的空载特性。理论分析与实验结果表明：采用双定子的电机结构可使电机空载相电动势比相同条件下的单定子电机增加约23%;通过调节励磁电流,发电机相电动势在90~110 V之间变化。由圆套筒型整体永磁体组成的串联磁路并设置2个定子的新型电机结构可有效地提高低速电机的发电能力;双定子混合励磁风力发电机具有较好的调磁性能。     

采用多级负载评估电梯永磁同步电机的退磁

为了研究电梯永磁同步电机的退磁状态评估，提出一种基于参数自调节滑模算法的永磁同步电机退磁故障检测方法，通过获取电机多级负载状态下的电压与电流数据，对电机的空载反电动势进行估算，并作为退磁评估依据。方法在使用传统滑模观测器(SMO)估算电机扩展反电动势的基础上，将不同负载下的永磁体的工作点变动及定子电阻、电感参数的变化纳入考虑，构建了电机空载反电动势估算误差方程。通过对滑模算法中的电阻、电感参数进行调节，来抵消上述因素的影响，进而实现对电机空载反电动势的获取，并根据电阻、电感参数对估算结果的不同影响特性，实现了电阻与电感参数的自调节。经过仿真分析与实验验证，该方法能够在无须测量编码器数据的前提下，对电机内部永磁体的性能进行量化分析，方法适用于局部退磁与均匀退磁两种故障类型，且准确度高，可用于电梯永磁同步电机外置退磁检测。     

混合磁极式的混合励磁永磁同步发电机

混合磁极式的混合励磁永磁同步发电机具有结构简单以及气隙磁场调节方便的优点.分析了该类电机的气隙磁场调节原理.基于电磁场有限元方法,介绍了齿磁通法计算电枢绕组空载电压波形的基本原理.应用该方法对一台混合磁极式的混合励磁永磁同步发电机的空载电磁场结果进行了后处理,得到了电枢绕组空载电压波形以及空载特性曲线.计算结果与实验结果比较验证了计算方法的正确性以及表明了该电机具有较好的气隙磁场调节能力.     

储能飞轮用大功率高速永磁同步电机电磁设计

储能飞轮用高速电机的工作状态包括电动机、发电机及空载三种。提高储能飞轮的能量转换效率、降低电机在各种运行状态的损耗成为其电磁设计的主要任务。从工程应用的角度,对储能飞轮用大功率高速永磁同步电机的绕组损耗、铁心损耗及涡流损耗进行了分析,重点分析了定转子间隙对转子构件涡流损耗的影响,同时提出了一种阶梯式转子永磁体结构,可满足永磁同步电机(PMSM)对空载反电动势的低谐波要求,并提出了转子护套材料的选取原则。最后通过一个算例介绍了电机的设计分析及性能参数的计算。     

Acceleration tests to determine salient pole synchronous motorinrush currents and torques

Determining torque and current at locked rotor and various slips during the acceleration test on a synchronous machine is very tedious and time consuming. Induction and synchronous machines behave similarly during acceleration except that synchronous machine acceleration can include a pulsation torque. Because of the salient poles, conditions exist where the synchronous motor has minimum torque at quadrature axis and maximum torque at direct axis during locked rotor or stall. Since synchronous machines do not have large numbers of rotor bars in the amortisseur winding, like the induction motor has in the squirrel cage, their stall times tend to be shorter. Due to the shorter stall time and large starting torque, locked-rotor torque and current are generally determined from acceleration tests conducted at reduced voltage rather than by tests at stand-still. Data showing that saturation effects impact both torque and current are presented in this paper. The data shows that the voltage index that has to be applied to the torque and current measured at reduced voltage varies with speed and can be obtained from a series of acceleration tests     

能自起动的抽水蓄能电站用双速同步发电─电动机，第一部分──原理

本文提出一种能自行起动的抽水蓄能电站用变极双速凸极同步发电─电动机，其机械结构和单速凸极同步电机一样，但转子极靴上不装阻尼笼，制造十分容易。作电动机运行时，不需要任何附加的起动装置，便能全电压直接起动，起动电流小，起动转矩大，容易牵入同步。该新型电机并有消除励磁绕组过电压，提高机组动态稳定性，显著改进作发电机运行时的电压波形等突出优点，用于抽水蓄能电站将获得巨大的经济效益和社会效益。     

稀土永磁同步电机的电枢电流分析

文章对比三相异步电动机的电枢电流轨迹图,通过分析稀土永磁同步电机的运行状态和矢量图,仿真了该电机的电枢电流轨迹图,得出电网电压波动对稀土永磁同步电机的带载能力和功率因数的影响,仿真结果在一台油田抽油用37kW的6极稀土永磁同步电机上得到验证。     

A method of power system simulation considering armature transients of synchronous machines

This paper presents a new method of simulating transient responses of multimachine power systems following a large disturbance. The conventional model used in the simulation is composed mainly of synchronous machine models in which the armature transients are neglected, and steady-state transmission system equations. This is because it is very difficult to treat the transmission system and the armature circuits of synchronous machines as differential equations. Naturally, the model cannot evaluate the effects of these neglected transients. The new method proposed herein uses the new synchronous machine model and the steady-state transmission system model. The former is obtained by modifying slightly the conventional armature-transient neglected model. Thus the resultant simulation model has almost the same structure as the conventional one. However, it can evaluate approximately the effects of armature transients on the dynamical behavior of the synchronous machines. For example, it can evaluate easily the angular backswing following a three-phase short-circuit fault. In addition, the new method can also estimate the maximum values of developed torque, induced voltage and armature current of synchronous machines at the moment when the disturbance occurred and when it was cleared.     

Dynamic Simulation of Radially Oriented Permanent Magnet-Type Electronically Operated Synchronous Machines with Parameters Obtained from Finite Element Field Solutions

A dynamic model for simulation of the transient interaction between radially oriented permanent magnet-type synchronous machines and their corresponding transistorized current source power conditioners is presented. Some key machine parameters used in this dynamic model were obtained from finite element field solutions. This dynamic model was used to obtain the transient interaction between a 15-hp samarium cobalt radially oriented permanent magnet electronically operated synchronous machine and its corresponding power conditioner. This machine was constructed for electric vehicle propulsion. Excellent correlation between various digitally simulated and actual test current and voltage waveforms, in various branches of the machine-conditioner network, has been achieved. These results are given. This modeling approach is applied to machines during the design stage, where the finite element modeling is the only way to obtain the necessary machine parameters for dynamic simulation. It is shown how such a combination of the computer-aided design tools can help in prevention of design mis-judgements that can prove costly to remedy once the hardware is in place. This is done through an actual design example of an additional machine being manufactured for electric propulsion applications.     

Before and during voltage sags

The relationship between the voltages and the tripping level for line-operated synchronous machines is discussed. Voltage sags may cause tripping and large torque peaks in electrical machines. Tripping is caused by undervoltage protection or overcurrent protection. The ability to keep synchronism for the synchronous machines is mostly related to the loading of the machine and not very related to the voltage before and after the voltage sag.     

同步发电机的动态阻尼力矩分析

根据由李亚普诺夫定理导出的综合阻尼系数的原理，统一定义了同步发电机的动态阻尼力矩系数和动态同步力矩系数。对同步发电机的阻尼力矩产生的机理进行了分析，并指出了使电力系统稳定装置产生阻尼力矩的同时，不致减少动态同步力矩的理论方向。     

Uncontrolled generator operation of interior PM synchronousmachines following high-speed inverter shutdown

Interior permanent magnet (IPM) synchronous machine drives are vulnerable to a special fault mode when gating is suddenly removed from the inverter switches during high-speed operation. The resulting IPM machine operation as a generator in combination with an uncontrolled rectifier must be properly understood and accounted for in the machine design to avoid damage to either the machine or inverter. An approximate closed-form solution is derived in this paper which relates the resulting machine phase current (and torque) to the IPM machine parameters, the DC-link voltage and the rotor speed. The resulting operating characteristics are particularly interesting for IPM machines that have been designed with inductance saliency ratios greater than 2 (i.e., high-saliency machines). The validity of the approximate solution is confirmed using dynamic simulation results, and the implications of these results for the machine designer seeking to minimize or eliminate the impact of this undesired operating mode are thoroughly discussed     

Synchronous Machines Adapted for Six Step Converters–Part II: Experimental Evidence

ABSTRACT

An investigation has been carried out to evaluate converter driven synchronous machines including a machine which is specially adapted for use with converters. The adapted machine has been designed so that the internally generated voltage is tailored to produce a desired current waveform when the machine is driven by a six step voltage source inverter. In this manner, the energy flows associated with commutation are supplied by electromechanical means. In the specific example presented, an armature current waveform is produced which is congrument with the applied armature voltage.

A short design study has been carried out which compares a conventional machine and an adapted machine of similar volume under converter driven operation. The rating of the adapted machine is slightly better than the conventional machine, although both are derated compared to the sinusoidal operation of the conventional machine.The adapted machine has a significantly improved power factor as well as smaller armature currents and reduced variations in shaft output power. Because of the reduced requirements for reactive power and armature current, it is expected that a simpler converter could be utilized. In addition to the design study, an experimental program has been carried out to demonstrate that the adapted machines will operate as predicted. An experimental machine in the 6 kw range was constructed and tested in a variety of conditions. The results of the experimental work agreed well with predicted behavior.     

Estimation of synchronous machine parameters from performance relations

The parameters of synchronous machines are required in system analysis, fault calculations, sizing of cables, circuit breaker selection, power factor correction, and voltage drop calculations. One of the major stumbling blocks is the general lack of design and application data. The design information is generally restricted and not commonly available to all users. Furthermore, the parameters are difficult to obtain through field measurements. In this paper, a mathematical model is presented to estimate the parameters of a synchronous machine from name-plate details. The data used in the estimation include output kVA, voltage, current, speed, rated power factor, field voltage, field current, and short-circuit ratio. The equations are derived from a well-known performance model and solved using a spreadsheet program available on any personal computer. Two case studies are presented in this paper. There is reasonable agreement between the estimated and available parameter values. Finally, the usefulness of this procedure and some of the limitations are outlined.