Speed estimation of induction motor drive using d‐axis slot harmonics and parameter identification method

This paper describes a rotor speed estimation technique of an induction motor, which utlizes slot harmonics on the d‐axis caused by permeance variation across the air gap. The frequency of the slot harmonics is a multiple of the actual rotor speed, and is proportional to the number of rotor slots. In order to extract the slot harmonics, a novel adaptive bandpass filter incorporating coordinate transformation is proposed, which is effective to estimate the rotor speed from 400 to 2000 rpm. This rotor speed estimation is applied to a field‐oriented controller as well as a speed controller. In addition, performance improvement is carried out by compensating a motor parameter mismatch. Feasibility of the proposed technique is confirmed through several tests, using a prototype experimental setup. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(2): 50–58, 2010; Published online in Wiley InterScience ( www. interscience.wiley.com ). DOI 10.1002/eej.20901     

Speed estimation method for ultrahigh‐speed induction machine utilizing rotor slot harmonics appearing in neutral point voltage

Recently the development of power electronics technology has made it possible to realize ultrahigh‐speed drives, and ultrahigh‐speed drives promise to be useful in various applications. This research aims at sensorless control drive of an induction machine in the ultrahigh‐speed region by utilizing rotor slot harmonics, which occur due to the structure of the induction machine. In this paper, we focus on the slot harmonics which appear in the neutral point voltage, and we propose a method for detection of the slot harmonics voltage and a speed estimation method utilizing the FFT with limitation of the detection band. The effectiveness of the proposed method and the possibility of speed sensorless control with the proposed method are illustrated through speed estimation results obtained both offline and online. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(3): 59–68, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21120     

降低谐波损耗的异步电机转子槽设计

在变频调速电机的应用中,电源中的高次谐波电流将引起集肤效应,使转子导条电阻及铜损耗增加,这是造成电机效率降低的根本原因,因此必须针对逆变器供电的特殊性设计异步电机。在对国外提出的一种带U形铁心桥的转子槽进行分析的基础上得出确定其尺寸的表达式,并通过电磁场有限元分析来验证,结果表明,这种转子槽能极大降低转子谐波电流、转子谐波损耗。最后,总结出转子槽尺寸与转子导条谐波损耗之间的变化规律,对以后设计该种转子槽具有指导意义。     

双馈电机数学模型及其应用

介绍了基于三相坐标系时，双馈电机及其循环变流器的数学模型，在所建数学模型的基础上，给出了应用所建数学模型计算得到双馈电机稳态运行时的转子电压波形，同时对该波形进行了频谱分析，对转子电压的谐波成分进行了分析，     

The Squirrel-Cage Induction Motor Model and Its Parameter Identification Via Steady and Dynamic Tests

One of the most important bases for designing robust closed-loop controllers applied to induction motor with high performance is establishing its mathematical model and state observers, as well as the parameter identification with high accuracy. In this paper, a step-by-step mathematical model of the squirrel-cage induction motor is described at αβ coordinate frame where the parameters are defined in detailed form; the rotor flux linkages and load torque are estimated via an asymptotic observer; the induction motor parameter identification is performed via a data acquisition board, applying dynamic and steady-state tests. Inductances of the induction motor model are calculated using the proposed relationships between the magnetically coupled circuit and equivalent circuit model. The mathematical model, state observers, and parameter identification procedure of squirrel-cage induction motor are validated via comparison of simulation signals with their corresponding real-time signals. This validation is made experimentally by a steady-state test, where load conditions are changed via a dynamometer which is belt coupled with the squirrel-cage induction motor.     

Dynamical Properties of Fast State Observer for Current-Fed Induction Motor

ABSTRACT

The paper is concerned with problems of nonmeasurable state variables reconstruction of the induction motor. The bilinear state observers were proposed for estimation of rotor flux of current-fed induction motor. The mathematical algorithms for state observers synthesis of proportional and proportional-integral type were presented. The digital simulation results of various type state observers worked together with current-fed induction motor were demonstrated and observers properties were discussed. Proposed observers are fast enough for real-time rotor flux estimation in the drive systems.     

A New Slip Frequncy Detector of an Induction Motor Utilizing Rotor Slot Harmonics

A method to detect slip frequency from rotor slot harmonics of a three-phase squirrel-cage induction motor is proposed. The rotor slot harmonic voltage Is obtained by summing the three phase voltages, and after being sampled with a multiple of the stator frequency, it is changed into slip frequency waves, from which a voltage proportional to the slip frequency is obtained. Sophisticated sampling techniques allow elimination of the third harmonic voltage induced in the sum of the three-phase voltages and also allow reduction of time constant of the slip frequency detector. Expenmental results show that the slip frequency detector has a good linearity in the range of slip frequency of about -50 to +30 percent of the stator frequency.     

New generalized D‐state observers for sensorless drive of permanent‐magnet synchronous motors. Impact of rotor flux harmonics to fundamental component estimate

This paper proposes new generalized D‐state observers as new minimum‐order flux state observers for sensorless drive of permanent‐magnet synchronous motors. The proposed generalized D‐state observers, which are established by a new approach using filters in the D‐module, contain the conventional D‐state observer as a special case, and the associated observer gain also contains the conventional one for the conventional D‐state observer as a special case. Consequently, the proposed generalized D‐state observers provide designers with a higher degree of design flexibility. In addition, for generalized D‐state observers, this paper presents a new analysis of the error in estimation of the rotor flux fundamental component due to rotor flux harmonics originating from nonsinusoidal magnetization, which has hitherto been an unsolved problem. It is analytically shown and verified by numerical experiments that harmonics appear in the flux estimate in a similar manner to the original rotor flux harmonics from the viewpoint of rotor phase error. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(2): 37–47, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20768     

Analysis of inverter-fed high-speed induction motor consideringcrosspath resistance between adjacent rotor bars

The purpose of this work is to analyze the steady state performance of an inverter-fed high-speed induction motor with trapezoidal rotor bars taking into account crosspath resistance between adjacent rotor bars. The performance of the induction motor drives for various crosspath resistances of two kinds of rotor slot shapes, a rectangular bar and a trapezoidal bar, is discussed on the basis of theoretical and experimental results of a 2.2 kW 500 Hz 15000 rev/min three-phase induction motor. It is also shown that the equivalent rotor resistance and leakage reactance change with crosspath resistance between adjacent rotor bars for various values of the fundamental supply frequency, the rotor slip, and the harmonics. The results of this research will be applied for design consideration of a high-speed induction motor with uninsulated rotor bars     

Modeling of induction machines including stator and rotor slot effects

Three-phase as well as single-phase induction machines form the backbone of a substantial portion of the adjustable-speed drives' applications. Among the current estimation techniques available for speed-sensorless induction motor drives, speed measurement based on rotor or principal slot harmonics (RSH or PSH) detection in machine line current happens to be a prominent one. In practice, two predominant RSH can be seen. The present paper attempts to investigate the effect of slot permeance on the production of RSH. Simulation studies on a small motor but with a popular stator, rotor slot, and pole combination suggest that their effect is less significant compared to rotor space harmonics effect. Also, out of the two aforementioned RSH, the cause of the less significant slot harmonic is shown to be the negative-sequence-current-induced reverse rotating field. Voltage unbalances and constructional imperfections can cause negative-sequence current even in a healthy machine. Thus, although the less significant RSH is absent in the simulated line current of an idealized machine running from a balanced supply, it can be detected in an actual machine.     

负载转矩和转子电阻未知任意情形下感应电机转矩无源性跟踪控制

应用无源性控制方法研究了在负载转矩和转子电阻为未知时变情形下感应电机期望转矩的跟踪控制问题。基于感应电机的Euler-Lagrange(E-L)模型,通过设计控制器、期望轨道、期望转矩、转子电阻估计器、负载转矩估计器、转子状态观测器,在理论上证明了可以实现对任意时变期望转矩的渐近跟踪,以及对负载转矩和转子电阻的快速估计。基于MATLAB/Simulink的仿真结果,证明了理论结果的正确性、有效性和高性能。     

笼型异步电动机转子断条故障检测新方法

计及实际电机本身所固有的非对称、气隙偏心、转子不对中及其它因素，进行高灵敏度、高可靠性的笼型异步电动机转子断条故障检测，是一个亟待解决并颇具工程意义的研究课题，该文即以此作为研究重心。首先完成了笼型异步电动机转子断条故障数字仿真与物理实验。通过分析仿真与实验结果，总结出在转子断条故障检测实践中保证其灵敏度与可靠性的原则及方法。在此基础上，首次将连续细化傅里叶变换、自适应滤波、转子齿槽谐波转差率估计、检测阈值自整定技术有机结合，形成了笼型异步电动机转子断条故障检测新方法。实验结果表明，该方法是切实可行的。     

基于快速参数辨识的感应电机转子温度在线评估方法

工程实际中,如何快速准确监测感应电机转子温度对电气设备状态评估、故障预测和安全生产具有重要意义。但受运行条件限制,转子温度很难直接测得且通过间接评估方法也存在较大难度。针对这一问题,提出一种快速参数辨识的转子温度评估方法,利用转子槽谐波辨识得到转子转速,进而利用可模拟电机堵转运行的起动初始阶段的实测电参数求解得出转子电阻。将上述求解得到的转速与转子电阻,当作实时辨识转子电阻的扩展卡尔曼滤波法(EKF)所需初值,避免了初值求解迭代时间过长的问题,实现了快速在线辨识转子电阻。进而基于金属材料电阻值与温度之间的关系,求出转子实时变化温度数据。以1台22 kW感应电机为例,辨识了负载条件下的转子温度情况,验证了所提出方法的有效性与可行性。     

基于热力学参数摄动分析的潜油电机温度辨识

为有效提高无传感器温度辨识方法的计算精度,将热力学参数摄动分析理论应用于潜油电机的温度辨识。基于潜油电机的网络热力学建模,给出潜油电机热参数,尤其是定、转子间耦合电阻参数摄动对电机温度变化的规律性。通过对所推导热力学方程进行频域根轨迹分析,可验证所取热力学参数的稳定性与合理性。仿真与实验结果表明,依据本文所提方法给出的潜油电机定、转子间耦合电阻等热力学参数得到的电机辨识温度可与实测结果相印证。     

Loss calculation of induction motors considering harmonic electromagnetic field in stator and rotor

A method of loss calculation for induction motors is proposed. The combined 3D–2D time‐stepping finite element analysis is carried out to obtain the copper loss and the time variation of the magnetic field in the motor. The iron loss is calculated approximately considering the time variation of the magnetic field direction and the minor hysteresis loops caused by the time‐harmonic fields using practical computer resources. The proposed method is applied to four types of induction motors, which are the solid rotor induction motors with/without slot and the cage induction motors with/without skew. The measured and the calculated total losses and the iron losses agree well in all cases. The differences of the loss distributions of each motor are also compared and investigated. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(2): 63–73, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10305     

永磁同步电机转子涡流损耗优化及温升分析

为解决永磁同步电机转子涡流损耗引起的转子温度高、永磁钢退磁等问题,建立转子涡流损耗解析表达式,分析影响参数,并以3相8极36槽V型IPMSM为例,研究定子槽口宽度、气隙长度、转子偏心距、定子斜槽角度等参数对转子涡流损耗的影响规律,完成最优参数匹配。研究结果表明,优化后的转子结构能够有效削弱电机主气隙磁密的高次谐波,从而减少涡流损耗、降低转子温度,提高电机输出性能。     

Experimental investigation of a speed‐sensor‐less IM drive system under Inverter fault‐tolerant control

This paper proposes an algorithm for fault tolerance of three‐phase, inverter‐fed, speed‐sensor‐less control of a three‐phase induction motor drive system. The fault tolerance of the inverter when one switch is open or one leg of six‐switch inverter is lost is considered. The control of the drive system is based on indirect rotor field‐oriented control theory. Also, the speed estimator is based on model reference adaptive system (using stator current and rotor flux as state variables for estimating the speed). The fault‐tolerant algorithm is able to adaptively change over from a six‐switch inverter to a four‐switch inverter topology when a fault occurs; also, it makes a smooth transition of the motor speed, torque, and current when changing over from a faulty condition to a new healthy status, which is four‐switch three‐phase inverter (FSTPI) topology; thus, the six‐switch three‐phase inverter (SSTPI) topology (pre‐fault status) is almost retained for the medium‐power range of induction motor applications. The proposed algorithm is simulated by using the MATLAB/SIMULINK package. Also, the proposed control system is tested experimentally using a digital signal processor (DSP1104). The obtained results from the simulation model and experimental system demonstrate the performance enhancement and good validity of the fault‐tolerance control for the speed‐sensor‐less induction motor drive system. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于辅助槽的切向永磁电机齿槽转矩削弱方法

为削弱永磁同步电机齿槽转矩,提高电机性能,采用了开设转子内部辅助槽的方法。通过能量法分析齿槽转矩的产生原理,探讨了转子内部辅助槽对电机齿槽转矩的影响;利用有限元软件建立8极36槽内置切向式永磁同步电机模型,并基于该模型对辅助槽的形状、各项参数进行分析,采用变步长搜索法得到最优参数,最终得到辅助槽的最佳设计方案。结果表明:在转子内部开设偏心圆形辅助槽,能够有效削弱齿槽转矩,使齿槽转矩峰值降低了57.2%;能够增加气隙磁密基波幅值,减少谐波分量,2、6、8次谐波幅值明显下降;电机感应电动势谐波含量减少,电机性能得到提升。     

复合笼条转子异步电动机的参数辨识

首先建立了复合笼条转子异步电动机的数学模型，然后利用推广的卡尔曼滤波法，将模型中转子电阻和漏感增广为状态变量，对其进行了辨识，利用辨识得到的参数对电机的起动过程进行了仿真，将复合笼条转子感应电机的转子参数及仿真结果与普通感应电动机进行比较，说明复合笼条转子异步电动机良好的起动性能。     

Potentiality of a new minimum‐order back‐EMF state observer taking acceleration into account for sensorless vector control of permanent‐magnet synchronous motors

This paper proposes new sensorless vector control methods for permanent‐magnet synchronous motors (PMSMs), which are based on a new minimum‐order back‐EMF state observer taking acceleration into account, and examines potentiality of the improved back‐EMF observer through experiments. Conventional sensorless vector control methods for PMSMs using an estimate of back‐EMF are established under the assumption of constant speed or zero acceleration, and consequently cannot operate properly at modes requiring rapid speed change especially in low speed region. On the other hand, the proposed back‐EMF observer has the following features: (1) it is a new back‐EMF state observer taking acceleration into account and requiring no additional approximation to motor mathematical model; (2) it is a minimum‐order state observer; (3) it utilizes motor parameters in the simplest manner; (4) it can be applied to both salient‐pole and non‐salient‐pole PMSMs; (5) it can be realized in both rotor and stator reference frames. Detailed designs and analyses for the improved state observer and the sensorless vector control systems in both rotor and stator reference frames are given. In relation to the sensorless vector control systems, this paper newly proposes a double‐integral‐type PLL method and an integral‐feedback‐type acceleration/speed estimation method. Their potentialities are examined through experiments. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 78–92, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20630