Showing papers on "Induction motor published in 2016"
TL;DR: A fast and accurate motor condition monitoring and early fault-detection system using 1-D convolutional neural networks that has an inherent adaptive design to fuse the feature extraction and classification phases of the motor fault detection into a single learning body is proposed.
Abstract: Early detection of the motor faults is essential and artificial neural networks are widely used for this purpose. The typical systems usually encapsulate two distinct blocks: feature extraction and classification. Such fixed and hand-crafted features may be a suboptimal choice and require a significant computational cost that will prevent their usage for real-time applications. In this paper, we propose a fast and accurate motor condition monitoring and early fault-detection system using 1-D convolutional neural networks that has an inherent adaptive design to fuse the feature extraction and classification phases of the motor fault detection into a single learning body. The proposed approach is directly applicable to the raw data (signal), and, thus, eliminates the need for a separate feature extraction algorithm resulting in more efficient systems in terms of both speed and hardware. Experimental results obtained using real motor data demonstrate the effectiveness of the proposed method for real-time motor condition monitoring.
905 citations
TL;DR: Compared with traditional neural network, the SAE-based DNN can achieve superior performance for feature learning and classification in the field of induction motor fault diagnosis.
562 citations
TL;DR: In this article, the authors proposed an improved model predictive torque control (MPTC) without the use of weighting factor, where the torque and flux magnitude references are converted into an equivalent reference vector of stator flux, hence eliminating the weighting factors of stators flux in conventional MPTC.
Abstract: Conventional model predictive torque control (MPTC) suffers from weighing factor tuning work and relatively high torque ripple, due to the different units of torque and stator flux and the limited number of voltage vectors. This paper proposes an improved MPTC without the use of weighting factor. The torque and flux magnitude references are converted into an equivalent reference vector of stator flux, hence eliminating the weighting factor of stator flux in conventional MPTC. Furthermore, two voltage vectors are applied during one control period to achieve better steady-state performance. Different from prior method using an active vector and a zero vector, the selected voltage vectors may be two nonzero vectors in the proposed method, which provides more opportunities to reduce both torque and flux ripples. The durations of the selected voltage vectors are determined based on the principle of stator flux error minimization. Both simulation and experimental results are presented to validate the effectiveness of the proposed method.
343 citations
TL;DR: In this paper, the authors investigated the performance of a synchronous reluctance motor and compared it with a permanent magnet-assisted synchronous motor, according to the typical requirement of a traction application.
Abstract: 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.
199 citations
TL;DR: A simplified algorithm based on a new direct torque control (DTC) switching table to reduce the number of VVs to be predicted and objectives to be controlled and the cost function is simplified by not requiring to include the frequency term.
Abstract: Finite-state predictive torque control (FS-PTC) is computationally expensive, since it uses all voltage vectors (VVs) available from a power converter for prediction and actuation. The computational burden is rapidly increased with the number of VVs and objectives to be controlled. Moreover, designing a cost function with more than two control objectives is a complex task. This paper proposes a simplified algorithm based on a new direct torque control (DTC) switching table to reduce the number of VVs to be predicted and objectives to be controlled. The new switching table also assists to reduce average switching frequency and its variation range. As a result, the cost function is simplified by not requiring to include the frequency term. Experimental results show that the average execution time and the average switching frequency for the proposed algorithm are greatly reduced without affecting the torque and flux performances achieved in the conventional FS-PTC.
197 citations
TL;DR: The loss analysis and thermal performance evaluation for a rotor of 100 kW, 32 km/min high-speed permanent-magnet motor and the influence of the stator core temperature on rotor thermal performance is analyzed by using a coupling simulation of fluid-temperature field.
Abstract: The rotor overtemperature caused by losses is one of the important issues for the high-speed electric machine. This paper focuses on the loss analysis and thermal performance evaluation for a rotor of 100 kW, 32 km/min high-speed permanent-magnet motor. The rotor temperature distribution based on the finite element method is obtained by accounting for various losses, including air-friction loss of the rotor, iron loss of the active magnetic bearing, and eddy-current loss of the motor. The influence of the stator core temperature on rotor thermal performance is analyzed by using a coupling simulation of fluid-temperature field. The temperature rise measurement of rotor is employed to study the impact of different cooling way on rotor thermal performance and to verify the computational accuracy of losses and temperature distribution. The analysis result of air-friction loss is compared with the measurement, which is obtained from the total losses by using the method of loss separation. It has great significance for the cooling structure design and the efficiency enhancement of electrical machine.
170 citations
TL;DR: This paper investigates a 20-pole–24-slot surface permanent magnet synchronous motor with consequent pole rotor for in-wheel direct drive since this topology is well suited for high-pole motors and thus high-torque direct-drive applications.
Abstract: In-wheel motors bring a fundamental change in electric vehicle technology by removing conventional mechanical components and freeing up space inside the vehicle body. This approach ultimately helps to realize all-wheel independent control for improved vehicle dynamics and increased vehicle design freedom. However, when space allowed for an in-wheel motor is taken into consideration, high torque density, high efficiency, and wide-speed-range capability are typically required. This paper specifically investigates a 20-pole–24-slot surface permanent magnet synchronous motor with consequent pole rotor for in-wheel direct drive since this topology is well suited for high-pole motors and thus high-torque direct-drive applications. Extensive finite-element analysis is carried out to characterize the proposed motor, and the practical feasibility of the proposed motor is discussed. Finally, the validity of the analysis was experimentally verified.
143 citations
TL;DR: Prior knowledge of the motor parameters, such as rotor speed and per-unit slip, which are needed by the other motor current signature analysis (MCSA) methods, is not required for the proposed method, which makes it more efficient compared with the other MCSA methods.
Abstract: The fault detection of electrical or mechanical anomalies in induction motors has been a challenging problem for researchers over decades to ensure the safety and economic operations of industrial processes. To address this issue, this paper studies the stator current data obtained from inverter-fed laboratory induction motors and investigates the unique signatures of the healthy and faulty motors with the aim of developing knowledge based fault detection method for performing online detection of motor fault problems, such as broken-rotor-bar and bearing faults. Stator current data collected from induction motors were analyzed by leveraging fast Fourier transform (FFT), and the FFT results were further analyzed by the independent component analysis (ICA) method to obtain independent components and signature features that are referred to as FFT-ICA features of stator currents. The resulting FFT-ICA features contain rich information on the signatures of the healthy and faulty motors, which are further analyzed to build a feature knowledge database for online fault detection. Through case studies, this paper demonstrated the high accuracy, simplicity, and robustness of the proposed fault detection scheme for fault detection of induction motors. In addition, with the integration of the feature knowledge database, prior knowledge of the motor parameters, such as rotor speed and per-unit slip, which are needed by the other motor current signature analysis (MCSA) methods, is not required for the proposed method, which makes it more efficient compared with the other MCSA methods.
137 citations
TL;DR: In this paper, a model-predictive flux control (MPFC) was proposed for induction motor drives, which uses the stator flux vector as the control variable and eliminates the complicated prediction of stator current at $k+2$ instant.
Abstract: Recently, model-predictive torque control (MPTC) has been introduced as a powerful control method for induction motor drives. However, the weighting factor for stator flux must be tuned carefully to obtain satisfactory performance at different operation points. Unfortunately, so far the tuning of weighting factor in MPTC is mostly based on an empirical procedure. This paper solves this problem by proposing a model-predictive flux control (MPFC), which uses the stator flux vector as the control variable and eliminates the complicated prediction of stator current at $k+2$ instant. As a result, the weighting factor in conventional MPTC is eliminated, and the control complexity is significantly reduced. Both MPTC and MPFC are tested and compared in detail, including steady-state performance, dynamic response, and low-speed operation. The simulation and experimental results prove that the performance of conventional MPTC is dependent on the weighting factor, and the improper weighting factor would lead to significant performance deterioration. On the contrary, the proposed MPFC achieves similar or even better overall performance over a wide speed range with very low tuning work. Hence, it is concluded that the proposed MPFC is more practical than conventional MPTC.
136 citations
TL;DR: A novel predictive model reference adaptive system (MRAS) speed estimator based on the finite control set-model predictive control (FCS-MPC) principle which improves the system robustness against motor parameter variations and increases the maximum bandwidth of the speed loop controller.
Abstract: This paper presents a novel predictive model reference adaptive system (MRAS) speed estimator for sensorless induction motor (IM) drives applications. The proposed estimator is based on the finite control set-model predictive control (FCS-MPC) principle. The rotor position is calculated using a search-based optimization algorithm which ensures a minimum speed tuning error signal at each sampling period. This eliminates the need for a proportional–integral (PI) controller which is conventionally employed in the adaption mechanism of MRAS estimators. Extensive experimental tests have been carried out to evaluate the performance of the proposed estimator using a 2.2-kW IM with a field-oriented control (FOC) scheme employed as the motor control strategy. Experimental results show improved performance of the MRAS scheme in both open- and closed-loop sensorless modes of operation at low speeds and with different loading conditions including regeneration. The proposed scheme also improves the system robustness against motor parameter variations and increases the maximum bandwidth of the speed loop controller.
134 citations
TL;DR: In this paper, the authors proposed a fast, real-time and fair robustness scheme for single switch and double switches open-circuit fault diagnosis in pulse-width-modulated voltage source inverter (VSI) for vector-controlled induction motor drives based on three phase output currents, which is also easy to insert into the controlled algorithm as a subroutine without major modification.
Abstract: This paper proposed a fast, real-time and fair robustness scheme for single switch and double switches open-circuit fault diagnosis in pulse-width-modulated voltage source inverter (VSI) for vector-controlled induction motor drives based on three phase output currents, which is also easy to insert into the controlled algorithm as a subroutine without major modification. The concept of allelic points is proposed and corresponding functions are defined to describe the symmetry of the VSI physical topology under healthy and faulty conditions. The residuals between any two phase functions are applied as criterion for allelic points. Under healthy condition, three legs are symmetrical and the residuals are all closed to zero, when open-circuit fault occurs, the residuals will be larger than a predefined threshold, so it is used to detect fault occurrence. When fault occurs, the near-zero current samples per fundamental period will get large, its proportions in a period will be different when different fault classes occur. The fault can be located combined the functions and residuals based on the analysis of VSI topology. The simulations and experiments are carried out and the results show the effectiveness and the merits of the proposed method.
TL;DR: Four thermal models for the stator-winding temperature prediction in short-time thermal transient are presented and experimentally validated and the behaviors of the proposed thermal models are corroborated by some considerations drawn by the analytical solution of the models.
Abstract: In this paper, four thermal models for the stator-winding temperature prediction in short-time thermal transient are presented and experimentally validated. The lumped-parameter networks, based on physical representation of the stator components, are composed of multiple RC cells in cascade. In particular, starting from a fourth-order thermal network, the model complexity is progressively reduced to a third-, second-, and then down to a first-order system. The proposed models and their predicted temperature evolutions are discussed in detail and validated by means of a full experimental approach on an industrial 7.5-kW induction motor. Finally, the behaviors of the proposed thermal models are corroborated by some considerations drawn by the analytical solution of the models.
TL;DR: In this article, a simple flux regulation for a direct torque control (DTC) of an induction motor (IM) to improve speed and torque estimations at low and zero-speed regions is presented.
Abstract: This paper presents a simple flux regulation for a direct torque control (DTC) of an induction motor (IM) to improve speed and torque estimations at low- and zero-speed regions. To accomplish this, a constant switching frequency controller (CSFC) is used to replace the three-level hysteresis torque comparator of a DTC IM. The DTC of IM utilizing CSFC (DTC-CSFC) retains the simple structure of a lookup table-based DTC drive. With DTC-CSFC, constant switching frequency is maintained, and at the same, the flux droop problem that normally occurs in DTC with the hysteresis controller (DTC-HC) at low speed is solved; subsequently, the stator flux and torque estimations at low speed are also improved. In the proposed system, the speed feedback for the closed-loop speed control is estimated using an extended Kalman filter, which requires heavy real-time computation. However, due to the simple structure of DTC-CSFC, small sampling time, hence large control bandwidth is possible. The performances of the speed sensorless DTC-HC and DTC-CSFC are compared experimentally under different operating conditions. With the improved stator flux regulation, experimental results of the DTC-CSFC showed a significant improvement in speed and torque estimations at very low and zero-frequency operations.
TL;DR: The proposed single-stage system is operated using an integrated control algorithm, which includes the maximum power point tracking, the V/f control, and the sample-averaged zero-sequence elimination (SAZE) pulsewidth modulation (PWM) technique, which improves the overall performance of the system.
Abstract: In this paper, a single-stage solution for solar photovoltaic (PV) pumping system using a dual-inverter fed open-end winding induction motor drive is presented. The three-level dual-inverter requires a low PV bus voltage compared with its conventional three-level counterpart. This could avoid large string of PV modules and helps in reducing the voltage rating of the capacitors and semiconductor devices used in the system. This may further help in reduction of cost of the system. The proposed single-stage system is operated using an integrated control algorithm, which includes the maximum power point tracking (MPPT), the $V/f$ control, and the sample-averaged zero-sequence elimination (SAZE) pulsewidth modulation (PWM) technique. While the MPPT algorithm ensures the extraction of maximum power from the PV source, the $V/f$ control improves the motor pump performance. Furthermore, the zero-sequence current is avoided by the SAZE PWM algorithm. Thus, the integrated control algorithm improves the overall performance of the system. Furthermore, this paper also presents the details of system design and analysis of its dynamic behavior during transient environmental conditions. The performance of the system is verified using MATLAB simulation and hardware prototype.
TL;DR: An online and non invasive technique that uses infrared thermography, in order to detect the presence of inter turn fault in induction motor drive, which is considered the most severe fault in the motors.
TL;DR: In this article, an improved rotor flux estimation method for the Torque model reference adaptive schemes (TMRAS) sensorless induction machine drive is proposed to enhance its performance in low and zero speed conditions.
Abstract: In this paper, an improved rotor flux estimation method for the Torque model reference adaptive schemes (TMRAS) sensorless induction machine drive is proposed to enhance its performance in low and zero speed conditions. The conventional TMRAS scheme uses an open loop flux estimator and a feedforward term, with basic low pass filters replacing the pure integrators. However, the performance of this estimation technique has drawbacks at very low speeds with incorrect flux estimation significantly affecting this inherently sensorless scheme. The performance of the proposed scheme is verified by both simulated and experimental testing for an indirect vector controlled 7.5-kW induction machine. Results show the effectiveness of the proposed estimator in the low- and zero-speed regions with improved robustness against motor parameter variation compared to the conventional method.
TL;DR: This paper proposes an efficient technique based on a neural network approach and Hilbert transform (HT) for broken rotor bar diagnosis in induction machines at low load and the results obtained are astonishing.
Abstract: The knowledge of the broken rotor bars characteristic frequencies and amplitudes has a great importance for all related diagnostic methods. The monitoring of motor faults requires a high resolution spectrum to separate different frequency components. The Discrete Fourier Transform (DFT) has been widely used to achieve these requirements. However, at low slip this technique cannot give good results. As a solution for these problems, this paper proposes an efficient technique based on a neural network approach and Hilbert transform (HT) for broken rotor bar diagnosis in induction machines at low load. The Hilbert transform is used to extract the stator current envelope (SCE). Two features are selected from the (SCE) spectrum (the amplitude and frequency of the harmonic). These features will be used as input for neural network. The results obtained are astonishing and it is capable to detect the correct number of broken rotor bars under different load conditions.
01 Jan 2016-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this paper, a precise piezoelectric motor capable of operating in either an AC drive mode or DC drive mode is presented, where the motor acts as an ultrasonic motor which is driven by two orthogonal mechanical vibration modes to generate elliptical motion at the stator to push the slider into motion.
Abstract: This study presents a novel precise piezoelectric motor capable of operating in either an AC drive mode or DC drive mode. In the AC drive mode, the motor acts as an ultrasonic motor which is driven by two orthogonal mechanical vibration modes to generate elliptical motion at the stator to push the slider into motion. In the DC drive mode, stick-slip friction between the stator and slider is used to drive the motor step-by-step. The experimental results show that the AC drive mode can drive the motor at a high moving speed, while the DC drive mode can simply drive the motor with a nanoscale resolution. In our experiments, a prototype motor is fabricated and its actions are measured. The results demonstrate that in the AC drive mode, the piezoelectric motor can achieve a 106 mm/s speed without a mechanical load and a 34 mm/s speed with 340 g of mechanical load when applying two sine waves with a drive of 11.3 V at 38.5 kHz. Meanwhile, in a DC driving mode, the motor is capable of performing precision positioning with a displacement resolution of 6 nm when driving at 100 Hz.
TL;DR: The proposed method is based on spectral preprocessing of the stator current followed by subspace decomposition of the signal autocorrelation matrix to detect relatively low-amplitude fault sidebands and is found to be very effective in detecting low-AMplitude sinusoids in a signal dominated by high-amPLitude fundamental.
Abstract: This paper presents an effective method of motor current signature analysis for detecting half- as well as full broken single rotor bar fault of a squirrel-cage induction machine under various loading conditions and speeds. The proposed method is based on spectral preprocessing of the stator current followed by subspace decomposition of the signal autocorrelation matrix to detect relatively low-amplitude fault sidebands. This method is found to be very effective in detecting low-amplitude sinusoids in a signal dominated by high-amplitude fundamental. The extended Kalman filter is used to estimate and track the fundamental component of the stator current. This component is subtracted from the measured stator current at every time step generating a resultant signal with a very low or negligible fundamental component. Subsequently, multiple-signal classification (MUSIC) is applied on the resultant stator current signal. Motor slip is estimated from principle slot harmonic to decide the approximate location of the fault sidebands. For effective fault detection, a hypothesis test is proposed to check the presence of sufficient fault frequency sideband in the current spectrum. This test works better if the lobe in the MUSIC plot due to the fault frequency is not distorted or overlapped by the fundamental component. Therefore, for each data window, the minimum size of the autocorrelation matrix is determined to generate distinct peaks. The proposed method applies to steady-state condition and is found to exhibit superior performance even during the light-load conditions with a half-broken bar.
TL;DR: In this article, a control scheme for the stand-alone generation system based on brushless doubly-fed machine (BDFM) is presented, where the output voltage amplitude and frequency are kept constant under variable rotor speed and load by regulating the amplitude and the frequency of the control winding (CW) current of BDFM appropriately.
Abstract: In this study, a control scheme for the stand-alone generation system based on brushless doubly-fed machine (BDFM) is presented. The output voltage amplitude and frequency are kept constant under variable rotor speed and load by regulating the amplitude and frequency of the control winding (CW) current of BDFM appropriately. The control scheme utilises a CW current vector controller as the inner loop, and a power winding voltage amplitude controller and a frequency controller as the outer loop. The proposed control scheme has been implemented on a prototype BDFM designed for the variable-speed stand-alone ship shaft generation application. Moreover, the satisfactory dynamic performance and low total harmonic distortion of the output voltage in the proposed stand-alone generation system is verified by experiments with two kinds of typical loads: three-phase induction motor load and three-phase RL inductive load.
TL;DR: In this paper, a dual three-phase asymmetric stator winding was proposed for multi-phase permanent magnet (PM) synchronous motors with asymmetric windings for safety-critical applications.
Abstract: Although three-phase permanent magnet (PM) motors are dominant in industry, multi-phase PM synchronous motors present higher torque-to-weight ratios, better efficiency, and low torque ripple compared with three-phase conventional PM motors. These features make fault-tolerant multi-phase PM motors become attractive for safety-critical applications. In this paper, a novel PM multi-phase motor design with a dual three-phase asymmetric stator winding is proposed. The winding structure of the proposed motor is unconventional due to selected slot–pole combinations. Therefore, an asymmetric winding is needed. The detailed finite-element analysis of the proposed motor and a performance comparison between the conventional integer-slot (72-slot/12-pole motor) with symmetric winding and the unconventional fractional-slot (78-slot/12-pole motor) PM motors with asymmetric windings is performed to see the benefits of the proposed motor. It was shown that the novel unconventional multi-phase PM motor has excellent torque quality and slightly higher torque density levels.
TL;DR: In this paper, the authors described fault diagnostic techniques of the single-phase induction motor based on the analysis of thermal images of electric motor and measured and analyzed 3 states of a single phase induction motor.
TL;DR: The control design is based on the backstepping technique complemented by the introduction of integral tracking errors action to improve its robustness and shows the characteristic robustness of the adaptive control to disturbances of the load, the speed variation and low speed.
Abstract: This paper presents a modified structure of the backstepping nonlinear control of the induction motor (IM) fitted with an adaptive backstepping speed observer. The control design is based on the backstepping technique complemented by the introduction of integral tracking errors action to improve its robustness. Unlike other research performed on backstepping control with integral action, the control law developed in this paper does not propose the increase of the number of system state so as not increase the complexity of differential equations resolution. The digital simulation and experimental results show the effectiveness of the proposed control compared to the conventional PI control. The results analysis shows the characteristic robustness of the adaptive control to disturbances of the load, the speed variation and low speed.
TL;DR: In this paper, the authors proposed the theoretical framework and the consequent application of the input-output feedback linearization (FL) control technique to linear induction motors (LIMs).
Abstract: This paper proposes the theoretical framework and the consequent application of the input–output feedback linearization (FL) control technique to linear induction motors (LIMs). LIM, additionally to rotating induction motor, presents other strong nonlinearities caused by the dynamic end effects, leading to a space-vector dynamic model with time-varying inductance and resistance terms and a braking force term. This paper, starting from a recently developed dynamic model of the LIM taking into consideration its end effects, defines a FL technique suited for LIMs, since it inherently considers its dynamic end effects. Additionally, it proposes a technique for the on-line estimation of the inductor resistance, based on model reference adaptive system (MRAS) on-line estimator; it has been exploited for adapting on-line the FL control action versus inductor resistance variations leading to undesirable steady-state tracking errors. The stability of the proposed MRAS on-line estimator has been proven theoretically, adopting the Popov's criterion for hyperstability. The proposed approach has been validated experimentally on a suitably developed test setup, under both no load and loaded conditions. It has been compared firstly with the simplest control structure, which is the scalar $V/f$ control, secondly under the same closed-loop bandwidths of the flux and speed systems, with the industrial standard in terms of high-performance control technique, i.e., field-oriented control.
TL;DR: In this paper, an analogy between the two control methods, when they are applied to the linear machines, is proved first, and the proposed control is particularly suitable for linear applications that need fast dynamics and smooth operation.
Abstract: Linear induction machines dynamics may not be as fast as that of their rotary counterparts due to a larger air gap, a bigger leakage flux, and end effect. Direct thrust control can speed up their dynamics substantially with rather high pulsations, while vector control facilitates a smoother performance but slower dynamics. In this paper, an analogy between the two control methods, when they are applied to the linear machines, is proved first. The analogy is then used to justify combining the selected parts of the two control methods to come up with a control method that provides faster dynamics than vector control and smother performance than direct thrust control. The proposed control method is realized by getting rid of demanding parts of the two conventional control methods. End effect is also considered in the modeling and control system design. Extensive simulation results confirmed by experimental results prove improved motor performances under the proposed control method. The proposed control is particularly suitable for linear applications that need fast dynamics and smooth operation.
TL;DR: Detailed simulation and experimental results are presented for the motor drive operating as an open-loop v /f controlled motor drive and as a closed-loop field-oriented motor controller.
Abstract: This paper presents a three-phase open-end winding induction motor drive. The drive consists of a three-phase induction machine with open stator phase windings and dual-bridge inverter supplied from a single dc voltage source. To achieve multilevel output voltage waveforms, a floating capacitor bank is used for the second of the dual bridges. The capacitor voltage is regulated using redundant switching states at half of the main dc-link voltage. This particular voltage ratio (2:1) is used to create a multilevel output voltage waveform with three levels. A modified modulation scheme is used to improve the waveform quality of this dual inverter. This paper also compares the losses in the dual-inverter system in contrast with a single-sided three-level neutral point clamped converter. Finally, detailed simulation and experimental results are presented for the motor drive operating as an open-loop v / f controlled motor drive and as a closed-loop field-oriented motor controller.
TL;DR: In this article, the authors proposed two space vector pulsewidth modulation (SVPWM) control strategies, namely the symmetric one and the asymmetric one, for five-phase fault-tolerant permanent magnet motors.
Abstract: Five-phase fault-tolerant permanent-magnet motors incorporate the merits of high-efficiency and high fault-tolerant capability. By adopting the fault-tolerant control technique, these motors can continue operating even fault occurs. This paper proposes two space vector pulse-width modulation (SVPWM) control strategies, namely the symmetric one and the asymmetric one. The novelty of the proposed SVPWM control strategies includes two parts. One is that voltage vector locations in both SVPWM strategies are reconfigured based on a new vector space diagram. Another is that the process of switching vector calculation under fault is similar to that under healthy condition. A five-phase fault-tolerant permanent-magnet motor drive is developed and the proposed fault-tolerant control strategies are evaluated in terms of the torque, voltage, current waveforms, and total harmonic distortion. Simulated and experimental results are provided to verify the effectiveness of the theoretical analysis.
TL;DR: This paper deals with monitoring of interturn short circuits of induction-motor (IM) stator windings operating under the direct field-oriented control (DFOC).
Abstract: This paper deals with monitoring of interturn short circuits of induction-motor (IM) stator windings operating under the direct field-oriented control (DFOC). Time transients are presented to illustrate the performance of the field-oriented speed control under the stator-winding damage. Novel detection algorithm is introduced, based on an analysis of the internal signals from the control structure: controller outputs and control path decoupling variables. The spectral analysis of these signals is used to detect the stator-winding incipient damages. Significant changes of the constant component ${f}_{{dc}}$ and the double-fundamental harmonic component $\text{2}{f}_{s}$ observed in these signals’ spectra under the stator-winding failure become the basis for the failure diagnostics in various operating conditions of the DFOC IM drive. The superiority of the proposed detection algorithm over the classical motor current signature analysis (MCSA) method is described. The online monitoring process is shown. Simulation and experimental results are presented to validate the proposed detection algorithm.
TL;DR: In this paper, a novel method to eliminate harmonics in a solar powered CHMLI (cascaded H-bridge multilevel inverter) is proposed, which uses Newton Raphson and PSO (Particle Swarm Optimization) based SHE (Selective Harmonic Elimination) techniques for solving the nonlinear transcendental equations and to obtain the optimal switching angles.