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Featured Application: This paper proposes a method of monitoring the condition of three-phase asynchronous induction motors running with no load based on computer analysis of the instantaneous active electrical power. This paper experimentally reveals some of the resources offered by the instantaneous active electric power in describing the state of three-phase AC induction asynchronous electric motors (with a squirrel-cage rotor) operating under no-load conditions. A mechanical power is required to rotate the rotor with no load, and this mechanical power is satisfactorily reflected in the constant and variable part of instantaneous active electric power. The variable part of this electrical power should necessarily have a periodic component with the same period as the period of rotation of the rotor. This paper proposes a procedure for extracting this periodic component description (as a pattern by means of a selective averaging of instantaneous active electrical power) and analysis. The time origin of this pattern is defined by the time of a selected first passage through the origin of an angular marker placed on the rotor, detectable by a proximity sensor (e.g., a laser sensor). The usefulness of the pattern in describing the state of the motor rotor has been demonstrated by several simple experiments, which show that a slight change in the no-load running conditions of the motor (e.g., by placing a dynamically unbalanced mass on the rotor) has clear effects in changing the shape of the pattern. [ABSTRACT FROM AUTHOR]

The interior permanent magnet synchronous motor (IPMSM) has a structure, in which a permanent magnet is inserted inside the rotor and cogging torque is generated in its structure. To solve this problem, various methods for reducing the cogging torque are being studied. The first method is to reduce the cogging torque by increasing the air-gap length by applying tapering to the rotor or stator core. However, in case of reducing the cogging torque above a certain level, the tapering application method may cause a decrease in output because the position and shape of the permanent magnet are restricted. The second method is to apply skew to the stator or rotor. This is the most reliable way to reduce the cogging torque, but the magnetization rate of the permanent magnet is low, so the manufacturability is low. In this article, we describe a rotor with rotational tapering that fuses the advantages of tapering and skew and offsets the disadvantages. The motor design used 3-D finite element analysis (FEA), and the validity of this article was verified by making the final model and comparing it with the simulation results. [ABSTRACT FROM AUTHOR]

This letter addresses experimental validation of the reduced-order natural speed observer design for position sensorless drive with nonsalient permanent magnet synchronous motor. The natural speed observer and the active flux estimator are connected in a cascaded fashion, which results in a simple sensorless algorithm that needs only to tune one bandwidth parameter for flux estimation and one bandwidth parameter for speed observation. Experimental results of high speed reversal test, zero speed stopping test, and slow speed reversal test are included, where the practice of applying nonzero $d$ -axis current at zero speed has shown to be effective for loaded zero speed stopping test, but it causes zero-speed locked-up at slow speed reversal with acceleration rate of $\rm \text{50}\,r/\text{min}/s$. Four remedies are compared to improve the slow speed reversal test and the proposed method gives almost ramp actual speed waveform, nondiverging $q$ -axis current and smooth transition in position waveform during slow zero speed crossing. A new dynamic expression of the active flux is proposed and with the aid of the active flux concept, the proposed sensorless algorithm is also applicable to various types of ac motors. [ABSTRACT FROM AUTHOR]

This article presents the design and development of the permanent capacitor split-phase ceiling fan motor with enhanced air delivery per unit power consumption. An existing single-phase induction motor ceiling fan is taken as a reference, and experimental performance is validated against finite element analysis (FEA). One factor at a time or monothetic analysis for existing lamination with turns in both the windings, a permanent capacitor connected in series with the auxiliary winding, an air gap length, stack length as parameters, and different loading is carried out in detail. Design modifications are proposed in stator lamination, and rigorous series of simulations are carried out. Two new motors are designed and prototyped for performance improvement, keeping the outer diameter of the motor same as an existing motor. The overall saturation of the motor is reduced by modifying the slot profile of the winding slots and increasing the overall volume of the motor. The designed motors are analyzed using FEA, and prototypes are tested for electrical performance and air delivery as per IS 374 standard. Both the results of prototypes show significant improvement in the power consumption and the air delivery with blades of an existing fan justifying the commercial viability of the improved design. [ABSTRACT FROM AUTHOR]

This study proposes a novel power supply system that utilises wind power to produce AC and DC power. A special designed generator based on bidirectional flux modulation effect is the key part of the proposed power supply system. The novel power system has a compact structure since the proposed generator has two electric port. There are three essential points that make the proposed system outstanding. One is the contra‐rotating rotors, which will cluster wind power even under low wind speed. Second one is the dual armature winding structure, which will provide AC and DC power simultaneously. There are two electric port in the proposed generator. One port can produce AC power to the non‐sensitive resistive load. The other can provide AC power with different frequency to the rectifier to obtain DC power. The induced voltage due to flux modulation effect can be used to offer AC power, and the induced voltage due to the outer rotor can be used to offer DC power. The voltage frequency of two sets windings is different. The last one is the air gap flux rotation speed amplification due to flux modulation effect. Time stepping finite element method is used to analyse the dynamic performance of the proposed machine. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) of power electronic converters has obtained much attention in many applications and especially in electric motor control. As the control loop is closed by predicting the future plant behavior by means of a mathematical model, disturbances and uncertainties are important aspects when using any MPC strategy. The plant model may be inaccurate due to plenty of reasons, such as parameter mismatches or the inverter nonlinearity. If these disturbances are not properly addressed during the MPC design process, the control performance is deteriorated. Hence, a suitable disturbance observer (DOB) is required to compensate for model inaccuracies. This contribution is comparing different lumped-DOB designs in the context of a continuous-control set MPC for induction motor current control. As a baseline for comparison, a field-oriented proportional-integral (PI)-type regulator is utilized which does not require a DOB due to its integral feedback.Comprehensive experimental results prove the necessity of a proper DOB; however, it is also shown that the overall transient and steady-state control improvement due to MPC has to be bought at a high price since the computational burden is at least doubled compared to the PI-baseline. [ABSTRACT FROM AUTHOR]

This article proposes a current-scaling gain-compen-sation algorithm for motor drive applications under the locked-rotor condition. In heavy industrial applications, such as elevators and cranes, initial commissioning tests are performed with the rotor locked. To compensate for errors in the current-scaling gain, the proposed method controls the current in the d–q axis using two-phase current-sensing methods in a stationary reference frame. The three-phase scaling gains are then estimated using the resulting d-axis current command and output voltage and are compensated for using these estimations. The proposed method delivers accurate compensations by considering the inequality between phase resistances. The effectiveness of the proposed algorithm is verified through simulations and experiments. [ABSTRACT FROM AUTHOR]

This two-part article compares the torque performance of 12 types of ac machines based on the same surface current density, tooth flux density, and rotor dimensions. Part II examines the torque capability of machines more recently developed which utilize the wave shaping capability of a solid-state frequency inverter. Essen's equation, as utilized in Part II, is modified to accommodate machines requiring non-sinusoidal waveforms. The “tau” factor, introduced in Part I, is also modified and is again used as means for comparison of any ac machine with an “ideal” machine based now upon a modified form of Essen's equation. [ABSTRACT FROM AUTHOR]

This article proposes a new predictive current control (PCC) strategy for a dual-inverter fed four-level (4-L) open-end winding induction motor drive (OEWIMD). The individual inverters of the dual-inverter system are operated with dc-link voltages, which are in the ratio of 2:1. In general, the PCC for the 4-L OEWIMD requires the evaluation of all of the 37 available voltage vectors (VVs) to select the optimal one. An improvised PCC is proposed in this article, wherein the inverter with lower dc-input voltage is clamped, while the other inverter is switched around it. An important feature of the proposed PCC is that it evaluates only five candidate VVs to determine the optimal vector. The simulation and the experimental results reveal that the performance of the proposed PCC technique is superior to the conventional PCC in terms of voltage and current total harmonic distortion (THD), torque-ripple, and total drive loss. Furthermore, the proposed PCC results in the reduction of the computational burden on the controller. Also, as the reduction of switching frequency is inherent in the proposed PCC strategy, there is no requirement to add an additional constraint to reduce it in the cost function. [ABSTRACT FROM AUTHOR]

This article investigates a novel two-converter-based operation of a brushless doubly fed reluctance machine (BDFRM). The BDFRM has a ducted rotor, and the stator is wound with two distributed windings, which are fed from two separate power converters. Operation theory with frequency sharing between the two windings is introduced. The prototype BDFRM design, machine assembly, and the corresponding motor drive implementation processes are discussed. The control strategy for frequency sharing mode of operation with two variable winding frequencies is discussed. Subsequently, the BDFRM drive is tested in frequency sharing mode at varying speed levels and loads. [ABSTRACT FROM AUTHOR]

In high-performance control of ac machines through variable frequency drives, the knowledge of machine parameters plays a decisive role. The accuracy with which machine parameters can be known is directly related to the time and effort put during the testing and commissioning process. In the ever-demanding industrial environments, the time spent on parameter identification translates into loss of production. To reduce commissioning times, research in this direction has focused on automatizing the identification procedure without loss of accuracy. This paper reviews different lines of research adopted over the past few decades for machine parameter identification. Parameter estimation of ac machines is considered because of their widespread applications from servomechanisms to traction to aviation. The surveyed works include self-commissioning schemes that have become an integral part and a salient feature of modern electric drives. This feature enables the drives to automatically identify machine parameters and tune the control loops. [ABSTRACT FROM AUTHOR]

Although colossal magnetoresistance (MR) with direct- or low-frequency currents ($f < 1$ KHz) in polycrystalline La0.7Sr0.3MnO3 sample has been extensively reported in the literature, magneto-transport in megahertz to gigahertz range is seldom studied. Here, we report the magnetic field dependence of ac resistance (${R}$) and reactance (${X}$) of polycrystalline La0.7Sr0.3MnO3 sample carrying high-frequency current ($f = 1$ MHz–3 GHz) in axial dc magnetic fields ($- 1\,\,\text {kOe} < H< 1\ \text{kOe}$) at 300 K. While R(H) shows a single peak centered around $H = 0$ for $1 \le f \le 30$ MHz, the peak transforms into a dip at $H = 0$ accompanied by double peaks at $H = \pm H_{P}$ for higher frequencies. The position of the double peaks shifts to higher magnetic fields with increasing frequency. Alternating current MR at 1 kOe increases from −0.7% for $f = 1$ MHz, −20% for $f = 50$ MHz, and +28% for 3 GHz at $H_{p}$. The transition from the single to double peak behavior is also seen in ${X}$ (${H}$) with additional features near-zero field for $f \ge 2$ GHz. While the enhanced value of the negative MR is attributed to the increase in magnetic skin depth due to the suppression of transverse permeability, the positive MR is attributed to the contribution from induced strong transverse permeability and ferromagnetic resonance. [ABSTRACT FROM AUTHOR]

This paper investigates the use of the Taguchi method for the design of line-start permanent magnet synchronous motors (LS-PMSMs). To address the inherent limitation of the Taguchi method in solving multiresponse optimization problems, an improved regression rate methodology and a weighted factor multiobjective technique are incorporated to form a Taguchi method based multiobjective design framework. To validate the proposed method, a prototype machine has been designed, constructed, and experimentally evaluated. It shows that the proposed method can effectively take into account both steady-state and transient synchronization performances in the design of LS-PMSMs. [ABSTRACT FROM AUTHOR]

In this paper, an improved predictive torque control without weighting factor is proposed for a voltage source inverter-permanent magnet synchronous motor drive system, which possesses good control performance of torque and stator flux. By investigating the relationship among torque, the reference stator flux amplitude, and the phase angle of the stator flux, the reference stator flux vector is constructed. Then, the reference voltage vector is calculated by the reference stator flux vector based on the delay compensation and the deadbeat control. The extended control set is designed and two generalized base vectors that require further screening are determined based on the position of the reference voltage vector to improve the calculation efficiency. And the duty ratios used for the generalized base vectors are calculated, according to the geometric relations between the generalized base vectors and the reference voltage vector. Finally, by the duty cycle control between two generalized base vectors and between each generalized base vector and zero vector, the candidate vectors are gained and substituted into the cost function only with the flux vector error term. Experiment tests were carried out and the results validated the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Fractional slot concentrated winding (FSCW) interior permanent magnet (IPM) synchronous motors are nowadays an attractive solution in automotive applications due to their advantages in terms of high performance and manufacturing simplicity. Among the different topologies, the spoke type is an effective configuration when high torque density is required. On the other hand, the motor performance are heavily related to the selected slot-pole combination. This choice is critical in demanding automotive applications, such as electric power steering (EPS) systems, where high constraints in terms of torque density, torque quality, flux weakening performance, and noise/vibration/harshness are requested. This paper deals with the design and analysis of eight optimal slot/pole combinations FSCW IPM spoke type EPS motors. Two different low cost heavy rare earths free PM typologies, ferrite and hot-pressed NdFeB, are considered. A design and optimization procedure based upon the finite element analysis is presented. The impact of the magnetic properties and the slot/pole combination on the optimal motor dimensions, torque density, and motor cost is discussed. Cogging torque, torque ripple, electromechanical performance, and the stator deformation of the machines are evaluated, and the results are compared, highlighting the advantages and the differences among the solutions. [ABSTRACT FROM PUBLISHER]

This paper presents a comparison of methodologies to incorporate control parameters into the design optimization of synchronous ac machines. A metric is used to quantify the conflict level between the average torque and torque ripple for an interior permanent magnet machine and a synchronous reluctance machine. Using 2-D finite-element analysis simulations, the results demonstrate that the traditional approach of lumping the control and design variables together can lead to poor designs, especially when the conflict is high. [ABSTRACT FROM AUTHOR]

In this work, we propose a new and simple method to insure an online and automatic detection of faults that affect induction motor rotors. Induction motors now occupy an important place in the industrial environment and cover an extremely wide range of applications. They require a system installation that monitors the motor state to suit the operating conditions for a given application. The proposed method is based on the consideration of the spectrum of the single-phase stator current envelope as input of the detection algorithm. The characteristics related to the broken bar fault in the frequency domain extracted from the Hilbert Transform is used to estimate the fault severity for different load levels through classification tools. The frequency analysis of the envelope gives the frequency component and the associated amplitude which define the existence of the fault. The clustering of the indicator is chosen in a two-dimensional space by the fuzzy c mean clustering to find the center of each class. The distance criterion, the K-Nearest Neighbor (KNN) algorithm and the neural networks are used to determine the fault type. This method is validated on a 5.5-kW induction motor test bench. [ABSTRACT FROM AUTHOR]

It was recently demonstrated that the synchronous reluctance motor is well suited for electric as well as for hybrid electric vehicles. This paper deeply investigates the capabilities of a synchronous reluctance motor and compares them with those of a permanent-magnet-assisted synchronous reluctance motor, according to the typical requirement of a traction application. A proper rotor design is necessary. The average torque is due to the rotor anisotropy. The permeance difference between the direct- and the quadrature-axis is achieved by means of a high number of flux barriers. The position of the flux barrier ends and proper rotor asymmetries are chosen so as to reduce the torque ripple, mainly due to the slot harmonics. The impact of the rotor design on the motor performance is presented deeply, showing several simulation and experimental results, carried out on synchronous reluctance motors with different rotor geometries. Permanent magnets can be inset in the flux barriers to assist the synchronous reluctance motor improving its capabilities, but avoiding to use rare-earth permanent magnets. The main advantages of the permanent magnet assistance is an increase of the main torque density and of the power factor. They are evaluated experimentally. However, the drawback of adopting permanent magnets is the possible demagnetization of the magnets themselves. This can greatly limit the maximum overload capability of the motor, which is a salient requirement of a traction motor. [ABSTRACT FROM AUTHOR]

This paper presents an input–output feedback linearization (FL) control technique for rotating induction motors, which takes into consideration the magnetic saturation of the iron core. Starting from a new formulation of the dynamic model taking into consideration the magnetic saturation expressed in a space-state form in the rotor-flux-oriented reference frame, the corresponding FL technique has been developed. To this aim, a particular care has been given to the choice of nonlinear functions interpolating the magnetic parameters versus the rotor magnetizing current and the corresponding magnetic characteristic. The proposed FL technique has been tested experimentally on a suitably developed test setup and compared, under the same bandwidths of the speed and flux closed loops, with both the FL technique not taking into consideration the magnetic saturation and with the industrial standard in terms of high performance control of the induction motor: field-oriented control. A further comparison with the unique example present in the scientific literature of the FL control technique including the magnetic saturation has been shown, highlighting consistent improvements achievable by the proposed FL in terms of reduced computational demand and better dynamic performance. [ABSTRACT FROM AUTHOR]

In the oil and gas industry, large synchronous motors are used to drive water injection pumps to support the pressure of a reservoir and to maintain the production level of a reservoir over a longer period. Therefore, failures in such motors will have an adverse impact on operation and production. Even though synchronous motors are superior to induction motors in relation to system voltage regulation and power factor correction, their starting is more complicated. As a result, the application of synchronous motors requires careful engineering analysis in the design stage of a project to determine system requirements for a successful operation. This paper presents a failure analysis case study for three 11 000-hp synchronous motors at a gas–oil separation plant along with the starting issues faced prior to the occurrence of a permanent damage. The fundamentals of dynamic motor acceleration requirements to achieve a successful start will be reviewed. In addition, results of site measurements and subsequent computer simulation will be presented. The simulation results were substantiated by a failure root cause analysis report provided by the manufacturer. This paper also discusses the obstacles faced as a result of erroneous and limited data availability, and the approach to overcome such difficulties. [ABSTRACT FROM AUTHOR]

This paper introduces the design and analysis of a new hybrid hysteresis motor with combined axial and radial flux rotors aiming to improve the poor performance characteristics of the conventional hysteresis motors such as the output torque and efficiency. The proposed hybrid design incorporates the advantageous features of both the conventional axial and radial flux hysteresis motors (RFHMs) in a unique structure. The design aspects and constraints of the proposed machine are based on a prestudied single-sided axial flux hysteresis motor (AFHM). In order to analyze the electromagnetic performance of the proposed structure and investigate the geometry specifications of the designed machine, a three-dimensional (3-D) finite-element analysis (FEA) is conducted. The hysteresis loop modeling is done based on the elliptical approximation of the hysteresis loop by considering the saturation during the FEA with an iterative method. Finally, in order to investigate the electromagnetic performance of the proposed device and the accuracy of the design and analysis approach, a prototype is built. The test results validate the good performance of the proposed machine. [ABSTRACT FROM PUBLISHER]

Alternating-current motor drive systems consume the majority of global electricity, but most of them are still not efficient enough. This paper proposes a complete solution to the efficiency enhancement of general induction motor (IM) drive systems with the least cost and a high reliability. On the motor side, the squirrel-cage rotors of IMs are replaced with optimally designed interior permanent-magnet (PM) rotors without damping windings; meanwhile, other assemblies remained unchanged. Stators with both wye- and delta-connected windings are investigated, and super premium efficiency (IE4) is achieved on all the remanufactured motors in this paper. On the drive side, the maximum efficiency per ampere algorithm is realized based on the position-sensorless control to better exert the motor efficiency and reduce the system cost. For applications where an original IM is used under a grid drive, this paper safely switches the remanufactured interior PM synchronous motors from an inverter to the grid drive. A total of seven prototypes with different rated powers and velocities are remanufactured, and various experiments are provided as the verifications of the effectiveness and practicability of the proposed solution. [ABSTRACT FROM PUBLISHER]

The performance of a speed-sensorless induction motor drive is poor at low-speed range. This is because the inverter nonlinear error, such as inaccurate motor parameters, deadtime, turn on/off delay, and on-state voltage drop of power switches, has strong influence on the speed estimation at low-speed range. In this paper, the feedback gains of an adaptive full-order observer are designed to guarantee the stability of speed estimation and to reduce the influence of the inverter nonlinear error on the speed estimation. In addition, the estimated current error caused by the inverter nonlinear error is identified offline. It is stored in the lookup table to compensate for the influence of the inverter nonlinear error on the speed estimation. The feasibility of the proposed method is verified by experiments. [ABSTRACT FROM AUTHOR]

This paper investigates the loss manipulation capabilities of deadbeat direct torque and flux control (DB-DTFC) induction machine drives. For each switching period, a volt-second-based inverse model provides a range of volt-second solutions to achieve the desired torque at the end of each switching interval, whereas the stator flux magnitude provides another degree of freedom to manipulate machine losses. With a flux-based DB-DTFC loss model proposed, losses can be manipulated each switching period without compromising torque dynamics. For a steady-state operation and typical process trajectories, the minimum loss can be achieved with corresponding energy savings. Alternatively, significant losses can be rapidly induced to dissipate kinetic energy in a machine during braking transients. This loss maximization technique provides significant braking torque without requiring additional hardware to transfer/dissipate energy. DB-DTFC induction machine drives provide an effective and elegant solution for continuous loss manipulation without compromising dynamic performance. [ABSTRACT FROM PUBLISHER]

In this paper, an investigation into an alternative topology for reluctance synchronous machine rotor flux barriers is presented. The investigated topology employs a high number of flux barrier variables with an alternative asymmetric rotor structure. The focus in this paper is on maximizing average torque and minimizing torque ripple, using finite element-based design optimization, in order to study the possibility of achieving acceptably low torque ripple. A subsequent investigation into the effect of rotor skew on the proposed optimized design to reduce torque ripple even further is also conducted, as well as the manufacturing and testing of the proposed flux barrier prototype. [ABSTRACT FROM PUBLISHER]

This paper describes a $d$– $q$-axis model of synchronous permanent-magnet machines at high frequency. Both the inductive and resistive saliencies are taken into account, and the model is suitable for investigating the self-sensing capability of the machines. It is proved that the high-frequency machine response can be described by means of three complex parameters, which form a symmetrical matrix. It is also shown that the high-frequency resistances between the $d$- and $q$-axes exist, and they may assume a negative value. Experimental results are included in this paper to prove the developed theory. [ABSTRACT FROM PUBLISHER]

To avoid inconvenience caused by shaft rotation and improve immunity to measurement noises, an elaborately designed scheme is proposed for parameter identification of induction motors. After analyzing the responses of a simple step-voltage test, a sequence of pseudorandom signals, customized to excite abundant dynamics in the featured frequency band of the motor, are injected into the stator in a single-phase mode at standstill. The crucial feature of the proposed scheme is that a nonlinear procedure is introduced to minimize “predicted errors” of the estimation model, which lowers influences of measurement noises notably, and thus the design of low-pass filters is simplified greatly. Experimental comparisons are carried out, including not only tests on a squirrel-cage motor, but also extended tests on a wound-rotor motor to testify accuracy of rotor-side parameters, both using a real inverter. The results indicate that the proposed scheme is able to estimate parameters required by controllers accurately in the noisy environment, and improve performances of sensorless motor drivers. [ABSTRACT FROM AUTHOR]

This paper presents a new topology of parallel hybrid excitation machine (PHEM), which integrates permanent-magnet synchronous motor (PMSM) and variable-reluctance machine, namely, doubly salient electromagnetic machine (DSEM), and provides a solution to better field-regulating capability. The configuration and the operation principle of the proposed PHEM are introduced. The combination criterion and design consideration are discussed. The performances of the two axial sections (PMSM and DSEM) are studied by 2-D finite-element analysis (FEA), respectively, to achieve reasonable integration. The field and voltage regulation capability of the PHEM is further investigated by 3-D FEA. A prototype PHEM is designed, manufactured, and tested. The measured results verify structural validity and finite-element predictions. The loss is predicted, and the measurement of short-circuit current illustrates the capacity of deexcitation at fault. The results confirm that the PHEM achieves effective power superposition of two different brushless machines. Bidirectional field-regulating capability facilitates a wide field regulating range of 6.5:1 under no load. [ABSTRACT FROM PUBLISHER]

Transient-based fault diagnosis in induction motors has gained increasing attention over the recent years. This is due to its ability to avoid eventual wrong diagnostics of the conventional motor current signature analysis in certain industrial situations (presence of load toque oscillations, light loading conditions, and so on). However, the application of these transient methodologies requires the use of advanced signal processing tools. This paper presents a detailed comparison between the two main groups of transforms that are employed in transient analysis: discrete and continuous. This paper does not focus on trivial fault cases but on difficult real situations where the application of the conventional methods often leads to false diagnostics (outer bar breakages in double-cage motors, motors with rotor axial duct influence, and combined faults). Indeed, it is the first time that continuous tools are applied to some of these controversial situations. The results in this paper prove the special advantages of the continuous transforms, tearing down some false myths about their use. [ABSTRACT FROM PUBLISHER]

This paper presents a new technique for fault detection and isolation to make the traditional vector-controlled induction motor (IM) drive fault tolerant against current and speed sensor failure. The proposed current estimation uses d- and q-axes currents and is independent of the switching states of the three-leg inverter. While the technique introduces a new concept of vector rotation to generate potential estimates of the currents, speed is estimated by one of the available model reference adaptive system (MRAS) based formulations. A logic-based decision mechanism selects the right estimate and reconfigures the system (by rejecting the signal from the faulty sensors). Such algorithm is suitable for different drives, including electric vehicles to avoid complete shutdown of the system, in case of sensor failure. The proposed method is extensively simulated in MATLAB/SIMULINK and experimentally validated through a dSPACE-1104-based laboratory prototype. [ABSTRACT FROM PUBLISHER]

The objective of condition monitoring of induction machines is to detect the incipient stage of a fault before serious damage occurs with high associated cost. Although the condition monitoring techniques have been intensively investigated in the last decades, research is still carried out in reducing cost and improving accuracy. This paper proposes a novel method that enables efficient and accurate monitoring of the stator winding circuit fault. The proposed method is based on the sparse grid optimization method applied in the least squares estimation of the circuit parameters that characterize the condition of a fault incipient. The kernel of the method is the efficient search for the objective function minimum on the grid created by using the hyperbolic cross points (HCPs). The system cost and complexity are minimized since the proposed method only requires voltage and current signals recorded at a machine terminal without any invasive or additional hardware circuitry. The proposed HCP algorithm is robust to supply voltage unbalance and motor loading state. The validity and effectiveness of the proposed scheme is experimentally tested on a three-phase 800-W 380-V induction motor. [ABSTRACT FROM PUBLISHER]

Motor current signature analysis (MCSA) based on the 50/60-Hz sidebands has become a common test in industry for monitoring the condition of the induction motor rotor cage. However, many cases of unnecessary motor inspection or outage due to false alarms produced by rotor axial duct interference have been reported. If the number of axial ducts and poles is identical, this can produce 50/60-Hz sideband frequency components in MCSA that overlap with that of rotor faults, resulting in false alarms. However, there currently is no practical test method available for distinguishing rotor faults and false indications other than testing the rotor offline or under the startup transient. In this paper, the feasibility of using the rotor fault frequency component produced by the space harmonic waves is evaluated as a solution for the first time. Since the fifth or seventh space harmonics have a spatial distribution of flux that does not penetrate in the rotor yoke to reach the axial ducts, they do not produce false alarms. The proposed method is verified on 6.6-kV motors misdiagnosed with broken bars via the 50/60-Hz sidebands of MCSA. It is shown that it provides reliable online indication of rotor faults independent of axial duct influence and can be used for screening out false alarms. [ABSTRACT FROM PUBLISHER]

Fault diagnostic algorithms in motor drives prevent damage to the motor, drive, and overall system by providing an additional level of safety. A single phase open (SPO) fault in a field-oriented controlled drive is one of the perilous faults that require immediate detection due to resulting oscillatory electromagnetic torque. SPO fault results in a significantly high electromagnetic torque ripple. The rapid mechanical vibration caused by the torque ripple exposes the system to failure modes. The single open phase fault detection algorithm proposed in this paper enables the rapid detection of the fault, with minimal system resources, compared to existing methods. Proof of accurate fault detection capability for a wide speed range is presented through simulation and experimental results. The proposed method is also capable of localizing the faulted phase via a novel time domain rotor reference frame current signature analysis. [ABSTRACT FROM PUBLISHER]

The canned induction motors are widely used in pharmaceutical, chemical, and nuclear fields. It is necessary to calculate the losses, particularly the can losses, accurately. Combining steady-state ac magnetic 2-D finite-element solutions with the can harmonic loss formulas derived in this paper, the can losses under rated voltage in various operating conditions are obtained. Then, the calculation results under various voltages in no-load condition are compared with the experiment data, which provides the basis for the further performance analysis and motor design. [ABSTRACT FROM PUBLISHER]

The rotor position is required in many control schemes in electrical drives. Replacing position sensors by machine self-sensing estimators increases reliability and reduces cost. Solutions based on tracking magnetic anisotropies through the monitoring of the incremental inductance variations are efficient at low-speed and standstill operations. This inductance can be estimated by measuring the response to the injection of high-frequency signals. In general, however, the selection of the optimal frequency is not addressed thoroughly. In this paper, we propose discrete-time operations based on a rotating voltage injection at frequencies up to one-third of the sampling frequency used by the digital controller. The impact on the rotation drive, the computational requirement, the robustness, and the effect of the resistance on the position estimation are analyzed regarding the signal frequency. [ABSTRACT FROM PUBLISHER]

The classical multiple signal classification (MUSIC) method has been widely used in induction machine fault detection and diagnosis. This method can extract meaningful frequencies but cannot give accurate amplitude information of fault harmonics. In this paper, we propose a new frequency analysis of stator current to estimate fault-sensitive frequencies and their amplitudes for broken rotor bars (BRBs). The proposed method employs a frequency estimator, an amplitude estimator, and a fault decision module. The frequency estimator is implemented by a zoom technique and a high-resolution analysis technique known as the estimation of signal parameters via rotational invariance techniques, which can extract frequencies accurately. For the amplitude estimator, a least squares estimator is derived to obtain amplitudes of fault harmonics, without frequency leakage. In the fault decision module, the fault diagnosis index from the amplitude estimator is used depending on the load conditions of the induction motors. The fault index and corresponding threshold are optimized by using the false alarm and detection probabilities. Experimental results obtained from induction motors show that the proposed diagnosis algorithm is capable of detecting BRB faults with an accuracy that is superior to the zoom-based MUSIC algorithm. [ABSTRACT FROM PUBLISHER]

This paper presents techniques for testing fractional horsepower (FHP) induction and brushless dc motors. The procedures for segregation of losses in these motors are presented. The issues encountered in testing FHP motors are discussed, and guidelines are provided to avert the issues. This paper also provides insights into understanding the test procedures outlined in the IEEE 114 Standard. [ABSTRACT FROM PUBLISHER]

Proximity and additional eddy-current losses can be difficult to calculate and if there are parallel paths then there can sometimes be increased losses which can be unexpected. The paper addresses these winding losses in a brushless permanent magnet machine with 18 slots, 16 poles and a spoke type rare earth magnet rotor. The winding has coils that are one pitch. Different simulation scenarios are investigated to illustrate the even when the windings are in slots they can still experience increased ac copper losses when rotating at high speed. High speed machines often have few series turns because of the high rate of change of flux linkage so they can have many parallel turns or strands in hand. Simulations are carried out at 12 000 r/min then some simulations are run at 4000 r/min for completeness. The simulations are run in a 2-D finite-element analysis environment. [ABSTRACT FROM AUTHOR]

In this paper, a sensorless method for low- and zero-speed operations is proposed for a high-power medium-voltage pulsewidth-modulated current-source-converter-fed interior-permanent-magnet motor drive system. The proposed method is based on the injection of a high frequency (HF) pulsating sinusoidal signal in the estimated synchronous reference frame of the drive's field-oriented control (FOC) scheme. The conventional FOC control scheme, low switching frequency, dc-link inductor, and the inverter output three-phase filter capacitor of the medium-voltage high-power current-source drive present some challenges in the generation and design of the HF-injection signal. To overcome these challenges, the FOC scheme is modified by introducing a modulation index control with suitable dc-link current compensation to enhance the dynamic response of the injected signal and prevent any clamp in the injected signal. In addition, a multisampling-space-vector-modulation method is proposed to prevent the distortion in the HF signal due to a low switching frequency to injected signal ratio. A detailed study and analysis regarding the influence of low switching frequency, output filter capacitor, and magnetic saturation in the injection method is carried out to determine the visible HF range of the injected signal. It is found that, by using the proposed FOC scheme and multisampling modulation scheme and by the proper design of the HF signal, an accurate rotor flux angle can be estimated for sensorless zero-/low-speed operations. Experimental results are provided to verify the proposed control method. [ABSTRACT FROM PUBLISHER]

This paper is concerned with a fixed-point implementation of the extended Kalman filter (EKF) for applications in sensorless control of ac motor drives. The sensitivity of the EKF to round-off errors is well known, and numerically advantageous implementations based on the square-root decomposition of covariance matrices have been developed to address this issue. However, these techniques have not been applied in the EKF-based sensorless control of ac drives yet. Specific properties of the fixed-point implementation of the EKF for a permanent-magnet synchronous motor (PMSM) drive are presented in this paper, and suitability of various square-root algorithms for this case is discussed. Three square-root algorithms—Bierman–Thorton, Carlson–Schmidt–Givens, and Carlson–Schmidt–Householder—were implemented, and their performances are compared to that of the standard implementation based on full covariance matrices. Results of both simulation studies and experimental tests performed on a developed sensorless PMSM drive prototype of rated power of 10.7 kW are presented. It was confirmed that the square-root algorithms improve the behavior of the sensorless control in critical operating conditions such as low speeds and speed reversal. In particular, the Carlson–Schmidt–Givens algorithm was found to be well suited for the considered drive. [ABSTRACT FROM PUBLISHER]

An equivalent dq model of three-phase flux-switching synchronous motors employing a segmental rotor is constructed and tested for predicting steady-state performance. Both the wound-field and permanent-magnet excited motors are represented. The unconventional topologies of the two types of motors present significant departure from the basic assumptions of the dq theory, even though the motors may be operated from a drive incorporating generic dq control regimes. The equivalent dq inductances and flux linkages are calculated from finite-element simulation results and applied in predicting the steady-state performance of the motor. It is found that the credibility of the dq model to predict the performance of the motors over the operating range is assured and is enhanced by incorporating dq-coupling inductances in the model. [ABSTRACT FROM PUBLISHER]

This paper presents the measured experimental results from a four-pole toroidally wound induction machine, where the stator is constructed as a prewound foldable strip. It shows that if the machine is axially restricted in length, the toroidally wound induction machine can have substantially shorter stator end windings than conventionally wound induction machines, and hence, it shows that a toroidally wound induction machine can have lower losses and a higher efficiency. This paper also presents the employed construction method, which emphasizes manufacturability, and highlights the advantages and disadvantages of this method. [ABSTRACT FROM PUBLISHER]

This paper proposes a sensorless speed control strategy for a permanent-magnet synchronous motor (PMSM) based on a new sliding-mode observer (SMO), which substitutes a sigmoid function for the signum function with a variable boundary layer. In order to apply a sensorless PMSM control which is robust against parameter fluctuations and disturbances, a high-speed SMO is proposed, which estimates the rotor position and the angular velocity from the back EMF. In the conventional SMO, a low-pass filter and an additional position compensation of the rotor are used to reduce the chattering problem that is commonly found in the SMO using the signum function. In order to overcome the time delay caused by the low-pass filter, in this research, a sigmoid function is used for the switching function instead of the signum function. Also, the variation in the stator resistance is estimated to improve the steady-state performance of the SMO. The stability of the proposed SMO was verified using the Lyapunov second method to determine the observer gain. The validity of the proposed high-speed PMSM sensorless velocity control has been demonstrated with simulations and real experiments. [ABSTRACT FROM AUTHOR]

This paper reviews many design issues and analysis techniques for the brushless permanent-magnet machine. It reviews the basic requirements for the use of both ac and dc machines and issues concerning the selection of pole number, winding layout, rotor topology, drive strategy, field weakening, and cooling. These are key issues in the design of a motor. Leading-edge design techniques are illustrated. This paper is aimed as a tutor for motor designers who may be unfamiliar with this particular type of machine. [ABSTRACT FROM AUTHOR]

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Due to its simple construction and excellent mechanical/ thermal stress withstanding capability, induction motor with solid-rotor structure is widely used in many high-speed, high pressure application fields. In this paper, a novel solid-rotor induction motor with skewed slits in both radial and axial directions is presented. The performance of the proposed solid rotor is simulated using time stepping finite element method (FEM). Because of the existence of the axial slits, the magnetic flux in the slit-rotor motor can penetrate, relative to those without slits, deeper into the rotor. Analysis shows that its torque is about 3.46 times of that of the motor with no rotor slits. By skewing the rotor slits in the radial direction in the novel motor being proposed, the torque is further increased by about 37.7% when compared with that of the motor with its rotor slits not skewed along the radial direction. Although more torque ripples are generated in rotors with skewed slits in the radial direction, it is shown that the torque ripples can be easily reduced by skewing of the slits along the axial direction. [ABSTRACT FROM AUTHOR]

This paper addresses the causes of synchronous torques in split-phase induction motors. First, an analytical model is outlined to describe the processes involved in producing synchronous torques. This involves the consideration of the motor MMFs interacting with the slot permeances. The results from the implementation of the model are given for several different motor designs to calculate the synchronous torques. These highlight the way that the synchronous torque is a function of the MMF and slotting relationships. Measurement of the synchronous torque is not straightforward; however, a method of assessment is developed in this paper by using a deceleration test and other tests. The test results are fully described in this paper, and they illustrate that even with correct bar/slot combinations and skew, synchronous torques still exist in the machine. [ABSTRACT FROM AUTHOR]

This paper presents a new technique for online identification of an induction motor rotor time constant. The technique is designed for a shaft-sensorless indirect field-oriented control induction motor drive with a model reference adaptive system (MRAS)-based speed estimator. The MRAS estimator is sensitive to the changes in the rotor time constant, and online identification of that parameter is essential. If rotor parameter error exists, it does not only change the achieved rotor speed, but it also changes the dynamic behavior of the whole field control and speed estimation structure. The proposed rotor parameter update is exactly based on the newly introduced dynamic model of the potentially detuned MRAS-based speed estimator. The technique avoids the use of test signals and rather extracts the needed information from the ever-present signal jitter, which is inherent to the current and speed servo loops. This paper demonstrates that the phase angle difference between some spectral components of selected small signals within the speed estimator can be used for rotor parameter update. Computer simulations and experiments are performed under a variety of conditions to validate the effectiveness of the proposed rotor parameter update technique. [ABSTRACT FROM AUTHOR]

Vector control accuracy of induction motor drives is affected by variations of motor parameters that are treated in the control algorithm as constant values, and by the phenomena that are not modeled at all and are therefore unaccounted for in the controller. Detuning sources of the first type include variations of rotor and stator resistance, mutual inductance, and leakage inductances, while the second category includes stator iron (core) losses. All these sources of detuned operation have been studied in a considerable depth in the past. It appears that the only potential source of detuned operation, which has never been studied before, is the stray load loss (SLL), which belongs to the category of unmodeled phenomena. This paper develops an analytical mode! that characterizes detuning due to SLLs in indirect rotor-flux-oriented (RFO) current-fed induction motor drives in steady-state operation by means of the orientation angle error, actual to reference rotor- flux ratio, and actual to reference-torque ratio. A quantitative assessment of the impact of SLL on accuracy of rotor-flux-oriented control is performed, with the necessary motor parameters obtained from IEEE 112-B standard measurements and subsequent equivalent circuit parameter fitting. Detuning is also examined in transient operation. It is shown that, although SLLs are comparable to the iron losses in the studied machine (of approximately the same value in the rated operating point), their impact on accuracy of vector control is much smaller when compared to the iron loss induced detuning. [ABSTRACT FROM AUTHOR]

The existence of broken rotor bars in induction motors can be detected by monitoring any abnormality of the spectrum amplitudes at certain frequencies in the motor current spectrum. it has been shown that these broken rotor bar-specific frequencies are settled around the fundamental stator current frequency and are termed lower and upper sideband components. Broken rotor bar fault detection schemes should depend, on multiple signatures in order to overcome or reduce the effect of any misinterpretation of the signatures that are obscured by factors such as measurement noises and different load conditions. Multiple discriminant analysis (MDA) provides an appropriate environment to develop such fault detection schemes because of its multi-input processing capabilities. The focus of this paper is to provide a new fault detection methodology for broken rotor bar fault detection and diagnostics in terms of its multiple signature processing feature and the motor operation partitioning concept to improve the overall detection performance. This paper describes two fault detection schemes within this methodology, and demonstrates that multiple signature processing is more efficient than single signature processing. The first scheme, which will be named the "monolith scheme," is based on a single large-scale MDA unit representing the complete operating load torque region of the motor, while the second scheme, which will be named the "partition scheme," consists of many small-scale MDA units, each unit representing a particular load torque operating region. [ABSTRACT FROM AUTHOR]