Transducerless position and velocity estimation in induction andsalient AC machines

This paper presents a viable transducerless rotor position and velocity estimation scheme for PWM inverter driven induction, synchronous, and reluctance machines with the capability of providing robust and accurate dynamic estimation independent of operating point, including zero and very high speeds, light and heavy loading. The injection of a balanced three-phase high frequency signal (500 to 2 kHz) generated by the inverter, followed by appropriate signal demodulation and processing combined with a closed-loop observer, enable the tracking of rotor magnetic saliencies from the machine terminals. Although rotor magnetic saliency is inherent within reluctance machines, and most synchronous machines, saliency in the induction machine is introduced via a modulation of the rotor slot leakage with minimal detrimental effects on the machine performance. Experimental verification for the induction machine is included     

互联系统交流联络线随机功率波动幅值研究

跨省电网互联后,会产生各孤立电网所不具备的新功效。电网互联后可提高系统的供电可靠性及旋转备用效益、有利于优化发电结构、降低运行费用等。但是正常运行时跨省级互联系统交流联络线上存在随机功率随机波动的现象,这种功率波动影响跨省互联系统联络线上的传输功率,严重时会威胁到电网的安全稳定运行,研究了随机功率波动的机制,并通过PSASP软件仿真及EMS系统的实测数据,对基于系统静态频率特性,推导的关于跨省级互联系统交流联络线功率波动的公式进行了验证,分析了影响联络线功率波动在理论计算与实测数据中产生误差的原因,为制定抑制联络线功率波动的措施提供依据。     

正弦交流采样理论误差的估计

交流采样技术在多种智能化仪表中得到广泛应用。它的主要思想就是在一个周期内用若干个交流信号瞬时值描述该交流信号波形,并计算出有效值及其它有关参数。一个周期内对交流信号来样次数与由采样次数所带来的误差关系。对比从理论上作了探讨。     

Analysis of estimation error of observer for disturbance torque and velocity

This paper analyzes some features of estimation error of the observer which estimates disturbance torque and velocity. This observer inputs the information of driving torque and current position, and outputs the information of disturbance torque and velocity. Although this observer is a practical tool to compose a robust control system, there has never been sufficient information to make the most of it. Thus the study to grasp some basic features of the observer is needed now. Also, it is very important to analyze the estimation error on it. This paper considers the estimation error caused by disturbance torque and observation noise because these seem to be the most significant causes. The result of analysis provides a practical way to select the pole allocation of the observer. Finally, the simulation and the experimental results are shown.     

Improved speed estimation in sensorless PM brushless AC drives

The application of flux-observer-based sensorless control to permanent-magnet brushless AC motor drives is described. Current methods of speed estimation are assessed, both theoretically and experimentally, and an improved method, which combines the best features of methods in which speed is derived from the differential of rotor position and from the ratio of the electromotive force to excitation flux linkage, is proposed. Its performance is verified experimentally.     

Methods of indirect estimation of motor velocity in VTC-IM systems

Methods of the indirect estimation of motor velocity in VTC-IM systems, including methods based on the calculation of motor differential equations and adaptive methods, are considered.     

数字化交—交变频器触发脉冲电路的研制

介绍了一种用于同步电机交流励磁系统中交—交变频器触发脉冲电路的工作原理及实用结果，并对其线路特点及工作过程作了详细的介绍和说明。     

Rotor position and velocity estimation for a salient-pole permanentmagnet synchronous machine at standstill and high speeds

This paper addresses self-sensing (“sensorless”) control of salient-pole permanent magnet synchronous motors (PMSMs). The major contribution of this work is the introduction of a simple-to-implement estimation technique that operates over a wide speed range, including zero speed. The technique achieves simplicity by decoupling the inherent cross-coupling in PMSMs. The technique utilizes the dependence of inductance on rotor position in interior permanent magnet machines to produce position and velocity estimates both for field orientation and for all motion control of the drives. The technique functions in a manner similar to a resolver and resolver-to-digital converter (RTDC) sensing system, whereby in the proposed technique the motor acts as the electromagnetic resolver and the power converter applies carrier-frequency voltages to the stator which produce high-frequency currents that vary with position. The sensed currents are then processed with a heterodyning technique that produces a signal that is approximately proportional to the difference between the actual rotor position and an estimated rotor position. This position error signal and a torque estimate are then used as inputs to a Luenberger style observer to produce parameter insensitive, zero lag, position and velocity estimates     

交直流混合系统状态估计算法研究与分析

采用最小二乘法对交直流输电系统的状态估计问题做了详细的分析和评价.在四种典型的交直流系统状态估计算法的基础上,增加了一类处理交直流系统之间关系的状态估计方法.针对五种算法对交流、直流系统的处理方法,采用一含有双端直流输电系统的14节点算例和一含有两条直流输电线路的300节点系统算例,进行多样本采样计算,从算法的优化效果,估计误差、迭代次数、对量测系统的适应性和计算速度等方面进行了详细的对比分析,总结了五种算法在不同的交流、直流系统量测配置情况下的计算性能,详细分析了几种算法的优缺点和实用性.针对电力系统状态估计的研究现状和现场需求,提出了直流系统状态变量的选取原则,对每个换流站只需选择两个状态变量即可,一个是直流电压,另一个是换流器控制角或换流变压器分接头.归纳出直流系统量测配置的特殊问题,即直流系统量测方程中必须包括无功量测或者触发角(熄弧角)量测,否则交直流混合系统状态估计发散的可能性比较大.     

High-resolution infrared technology for soft-tissue injurydetection

Until recently, the application of infrared imaging to medicine has been limited by low-precision temperature measurement, low spatial resolution, a narrow field of view and the lack of image-processing ability. These shortcomings have been overcome and now modern cameras have the ability to accumulate many sequential images, thus permitting the study of dynamic phenomena. In this article we present several examples of soft-tissue injury and breast cancer detection where the use of appropriate image-processing algorithms substantially enhanced the diagnostic acumen of infrared imaging     

DC-Modulated PFC Buck-Type AC/AC Converter for Light Dimming

1 Introduction Dimmers are very widely applied in theatres,cinemas,auditoriums and signal systems.They are usually supplied by single-stage AC/AC converters in thepast with voltage regulation technique.Light dimmingrequests the power supply voltage fromth…     

Rotor and flux position estimation in delta-connected AC Machines using the zero-sequence carrier-signal current

This paper analyzes carrier-signal voltage injection zero-sequence current-based sensorless control techniques for delta-connected three-phase ac machines. The analysis will focus on rotor position estimation (tracking of rotor-position-dependent saliencies), but the method applies equally well to flux position estimation (tracking of flux-dependent saliencies). The paper first develops a theoretical model and then provides analysis of relevant implementation aspects, such as selection of carrier-signal frequency and voltage magnitude, measurement of the zero-sequence carrier-signal current, measurement and compensation of saturation-induced saliencies, and the signal processing needed for position/flux angle estimation. A similar implementation to that proposed in this paper, and with practically the same performance in terms of accuracy and estimation bandwidth, can be obtained for the case of wye-connected machines using the zero-sequence carrier-signal voltage, as shown in IEEE Trans. Ind. Appl., vol. 41, no. 6 pp. 1637-1646, Nov./Dec. 2005.     

基于电流型Z源交流调压器的电机调速系统

提出了基于电流型Z源交流调压器的电机调速系统.这种新型的Z源交流调压器系统引入了独特的LC网络,减少了由于开关直通或开路造成的过电流和过电压.通过控制双向电力电子开关的占空比,这种系统可以提供升降压功能.因而,在电网电压跌落时,可以为电机提供渡越能力,减小网侧的电流谐波,提高功率因数和系统的可靠性.仿真和实验结果验证了理论分析的正确性.     

交流接触器、交流电磁铁直流运行节能电路

1　引言交流接触器、交流电磁铁是用来控制电动机、电炉、机械设备的启动、停止 ,是经常使用的一种低压电器。交流接触器是通过交流电工作 ,在磁系统调整不好时会出现振动和噪声 ,运行电流大、温升高 ,严重时还会烧坏线圈 ,特别是大功率交流接触器 ,这些问题更为突出。同时交流接触器功率因数低 ,浪费电能。因此 ,有必要对交流接触器进行改造 ,较有效的办法是将交流接触器改为直流运行。交流接触器改为直流运行 ,优点很多。比如 ,可以消除运行时的振动和噪声 ,改善劳动环境 ;可以降低释放电压 ,使交流接触器线圈温升显著降低 ,从而延长了接…     

A Clamped AC?AC Frequency Converter for Induction Heating

A clamped load-commutated ac-ac frequency converter for induction heating applications is presented. The converter provides variable frequency, continuous output current with low harmonic distortion, and has an optimum performance in the medium frequency range of 400 Hz to 3 kHz. A steady-state analysis of the converter for a series/parallel compensated load is presented. The effects of changes in circuit parameters on the operation of the circuit are described and preferred operating conditions are established. Test results on an experimental setup are presented.     

Z源AC/AC变换器的谐波消除PWM技术

为保证敏感负载的高品质电能供应,提出一种应用于Z源AC/AC变换器的谐波抑制PWM技术.基于变换器的工作原理,分析和推导谐波抑制调制函数的解析式,给出控制方案.通过开环方式,对变换器的输出开关占空比进行实时调节.与已有的恒定占空比控制相比,实现对交流输入电压中各次谐波的有效抑制,并且不要求分别计算各谐波分量,简化了控制...     

自然换流AC/AC变频控制器数字化实现方法

针对AC/AC变频电路存在的换流死区问题,提出了一种AC/AC变频控制器软、硬件设计方法.该方法中6路触发脉冲均由DSP生成,完成对系统的全数字化控制.通过DSP中两个定时器的合理使用,实现了AC/AC变频器的自然换流,减小了换流死区对输出波形的影响.实验结果表明,所设计的AC/AC变频数字控制系统具有较高的控制精度和...     

交流接触器的可靠性技术

交流接触器是一种量大、面广的低压电器产品,广泛应用于电力系统和控制系统,其质量与可靠性的提高至关重要.探讨了提高交流接触器寿命与可靠性的技术措施,包括采用微电子技术和计算机技术实现交流接触器选相合闸、无弧分断,提高其触头的寿命,大大减弱或消除了由电弧产生的电磁干扰.最后讨论了电子控制装置的抗干扰技术和复式电源双路供电技术.     

多电动机交流传动系统

艾默生公司的TD2000和TD3300变频器及其在由其组成的塑料薄膜挤出机的控制系统,能实现多电动机速度的同步,卷取机的开环张力恒定控制。本控制方案能提高调速精度,降低成本,使系统简洁、稳定。