Search

Discrete space vector modulation (DSVM) is employed to synthesize large number of voltage vectors (VVs) to improve the steady-state performance of predictive torque control (PTC). However, enumerating all the VVs in the prediction process increases the computation load of the motor drive. To address this issue, this article proposes a unidirectional VV preselection (UVVP) method for optimizing the performance of DSVM-based PTC of ac motors. The proposed UVVP method divides both voltage space vector diagram (VSVD) and flux space trajectory into twelve 30° based sectors to reduce the impact of candidate VVs with negative effects. At each flux position, the UVVP strategy can restrict the nearest candidate VVs in the 30° based VSVD region within the circular flux trajectory. This is achieved by using the speed direction to avoid the candidate VVs, which are in the same flux sector for reverse flux rotation, hence resulting in significant flux and torque ripple reduction. The main benefit of the proposed method is its simplicity since it only requires the flux sector and speed information as well as it can generate the VV enumerations online while ensuring the reduction of computation burden. [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]

Dual three-phase permanent magnet synchronous machines (DTP-PMSMs) have received increasing attention from the industry and academia due to their advantages in lower burden on power inverters when operating in high power applications compared to the three-phase counterparts and low torque ripples. In this article, it reveals that the favorable low torque ripple characteristic of DTP-PMSM is undermined in the high power and overload operating mode. To solve this problem, this article proposes a novel torque ripple suppression strategy based on optimal harmonic current injection. A mathematical torque ripple model of DTP-PMSM considering the cross-coupling effects between d–q axis and dq-z1z2 axis is built. And based on this model, a detailed analysis is carried out to obtain the optimal harmonic current. The theoretical analysis also guarantees that the induced machine loss is minimum. Moreover, the proposed strategy has good dynamic performance since the algorithm involves no iterative computation and is computationally effective, which is proved on a laboratory DTP-PMSM system. The effect of parameter variation is also discussed and tested. The experiment results prove that the influence of magnetic saturation on torque ripple can be effectively suppressed. [ABSTRACT FROM AUTHOR]

Unavoidably, the controlsystem of any permanent magnet synchronous motor (PMSM) is subjected to perturbations, e.g., motor nonidealities and inverter nonlinearities. To reject these perturbations, a new super-twisting (ST) control variant, called speed adaptive super-twisting (S-AST) control, is proposed in this paper. In the S-AST control, a proportional-integral (PI) and a ST controllers are merged using an adaptive law that is based on the motor speed measurement. This is done to reduce the chattering problems that the standard ST control presents. In addition, a mathematical design for the S-AST control is proposed, where the relationship between the chattering amplitude, the switching frequency and the system perturbations is shown. The main contribution in this paper is the application of the S-AST controller to reduce the total harmonic distortion (THDi) of the PMSM currents. By comparing the S-AST control against PI control, the THDi is reduced from 9.9% to 1.27%, in simulation, and the THDi is reduced from 22.79% to 1.56%, experimentally. These results demonstrate how the S-AST control is an excellent alternative to improve the waveform of the PMSM currents. [ABSTRACT FROM AUTHOR]

An 8-pole 48-slot dual three-phase synchronous reluctance motor has been tested under half control mode, that is, when only a single three-phase system is supplied while the other is not operating. Changing the terminal connections of the motor prototype available, two different winding configurations have been tested. This allows their performances to be experimentally compared. At first, the cross coupling effect between the axis in $dq$ reference is analyzed, by measuring the flux linkages for different current combinations. The torque characteristics are compared in terms of torque map, maximum torque capability and torque ripple. Then the finite element analysis has been used to explain the experimental results and to investigate the radial forces on the rotor. Finally, the impact of a lack of symmetry between the two three-phase system is investigated. [ABSTRACT FROM AUTHOR]

This article proposes a novel dual three-phase flux-modulated switched reluctance motor (SRM) drive with maximum torque per ampere (MTPA) capability. Different from the existing open-winding structure, the stator winding is in dual three-phase connection, which effectively eliminates the side effects of the zero-sequence harmonic voltage component. Hence, the modulating region of the space vector pulsewidth modulation can be enhanced together with the increase of the dc-link voltage utilization ratio. The mathematical models of the dual three-phase flux-modulated SRM in the stationary reference frame and synchronous rotating reference frame are analyzed in detail. By considering the inductance nonlinearity, the MTPA control strategy is proposed based on the polynomial fitting method, which not only improves the torque capability but also simplifies the calculation of the current control system. The contributions of fundamental and harmonic currents to the electromagnetic torque are considered. By online adjusting the ratio of the dc-biased current component to the ac current component, the torque capacity can be improved. Besides, the effectiveness of the proposed MTPA control strategy can be enhanced by suppressing the harmonic current components caused by distorted back electromotive force. Experimental validations are provided to verify the effectiveness of the proposed SRM drive. [ABSTRACT FROM AUTHOR]

An electrolytic capacitor-less single-phase to three-phase power converter controls the motor and the input power factor. However, the motor power and the torque are pulsated because the input power of the inverter is irregular. This article proposes a power converter and control method to realize a high input power factor and constant motor torque using a dual inverter without an electrolytic capacitor and an open-end winding machine. The proposed system has the following features. First, the proposed control method achieves a high input power factor by controlling the single-phase ac power without affecting the motor current. Second, the proposed control method compensates the pulsation the of load voltage by using an additional inverter. The proposed circuit configuration and control method contributes to the small size and weight, and high efficiency of the motor drive system with a single-phase power supply. The effectiveness of the proposed system is verified through experiments. The proposed system suppresses torque pulsation by 95.5% compared to the conventional system, and the input power factor is 97.2% at 1.5 Nm and 2500 r/min load condition. [ABSTRACT FROM AUTHOR]

Finite control set model predictive torque and flux control of ac motor drives commonly selects optimum inverter switching states through a cost function with a required weighting factor. The weighting factor should be well-tuned in accordance with the motor specifications and operating points. Additionally, the control performance of the drive is degraded under the parametric uncertainties. In this article, a predictive torque and flux control method is proposed for interior permanent magnet synchronous motor drives without a cost function. As a result, the tuning of the weighting factor is avoided. Besides, an estimation scheme based on a data-driven model is adopted, which enhances the robustness of the drive against parametric uncertainties. Instead of directly using the motor parameters, the input and output data of the control system, i.e., voltage and current, are used for estimating three new coefficients employed in the predictions. The performance of an interior permanent magnet synchronous motor drive under the proposed control method is evaluated and compared with those under the conventional predictive torque control method and a recently developed predictive torque control method without a weighting factor. The results confirm the effectiveness of the proposed control method and its superiority over the other two methods. [ABSTRACT FROM AUTHOR]

The overmodulation operation of a three-phase inverter can enhance the output torque capacity of the AC motors. In this case, the enhancement varies depending on the overmodulation schemes applied for the overmodulation operation. Steady-state overmodulation schemes are usually employed to give the unit voltage gain up to the six-step mode of an inverter. However, these schemes lead to a slow transient response of the output torque and require a complex algorithm for implementation. On the other hand, dynamic overmodulation schemes can achieve a rapid transient response of the output torque and are simple to implement. However, inverters using these schemes cannot work up to the six-step mode since the voltage gain of the inverter is less than one in the overmodulation region. In this paper, a technique is proposed that can increase the DC voltage utilization of an inverter by improving the voltage gain in dynamic overmodulation operation. An inverter with dynamic overmodulation using the proposed technique can work up to a six-step mode. Hence, AC motors can obtain enhanced torque capacity during flux-weakening operation. Consequently, an improved transient torque response can be achieved in the high-speed region. From simulation and experimental results, it was validated that the proposed technique can be used for dynamic overmodulation operation for not only the continuous PWM but also the DPWMs (discontinuous pulse width modulations). [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]

Motor speed signature analysis provides a noninvasive method for bearing fault detection. However, for the vector-controlled ac motors, periodic speed ripples related to fundamental frequency $f_{e}$ and its twice harmonic $2f_{e}$ , which are caused by current measurement errors, are difficult to be attenuated by motor inertia or bandwidth of speed loop under low-speed conditions. The unwanted components would reduce the signal-to-noise ratio of motor speed and increase the difficulty of bearing fault detection. To solve the problem, this paper proposes a new noise cancellation strategy, which applies the improved drive algorithm instead of conventional signal processing schemes to cancel out the noise component before the data acquisition. Specifically, resonance controllers are introduced and set in parallel with the existed proportional–integral controller to suppress the speed ripples. Moreover, the envelope spectrum analysis is carried out to detect fault characteristic. The effectiveness of the proposed method is validated through simulation and experimental tests. Besides, its superiority under low-speed conditions is also demonstrated, compared with the spectral kurtosis of speed signal and three current-based methods. [ABSTRACT FROM AUTHOR]

In this article, a new online continuous control set-predictive controller (CCS-PC) is proposed with the objective of minimizing the stator-flux and torque ripples. In this controller, a constrained optimization problem is constructed to optimize the phase, amplitude, and time duration of the voltage vector applied to the motor. Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) which is an advanced algorithm based on fast proximal gradient method is adopted to find the optimal solution in an online manner. In each control period, FISTA is executed 10 times where the voltage vector found in the last iteration is considered as the optimal voltage vector. Performance of the proposed controller is compared with the performance of an offline CCS-PC through various experiments. In these experiments, stator-flux ripple, torque ripple, stator-current total harmonic distortion, and computational complexity of the controllers are compared with each other. Based on the results, pros and cons of the proposed online CCS-PC are highlighted. [ABSTRACT FROM AUTHOR]

Integral-slot electrical machines require modifications and optimization of both stator and rotor to maximize the machine performance. In addition, sub-harmonics in magneto-motive force distributions is an important issue in motors with fractional-slot concentrated windings. These additional sub- and super-harmonics increase iron losses, which becomes an even bigger challenge in high speed/frequency applications. A permanent-magnet (PM) motor with unbalanced winding (UBW) and unconventional slot numbers is a good option for applications that require smooth torque output and low back electromotive force voltage harmonics. In this paper, different winding configurations and displacements of an unconventional nine-phase PM motor with both balanced fractional-slot winding and UBW structures have been investigated. The focus has been on 117-slot with 12-pole (for the balanced winding motor) and 36-pole (for the UBW motor) combinations. Motor prototypes with UBW configurations have been manufactured. The finite-element analyses results have been validated with experimental results and it is shown that such unconventional slot/pole combinations can be a good option for some high-power applications. [ABSTRACT FROM AUTHOR]

This paper proposes the novel scalable saturated model of synchronous permanent magnet machines, which combines ultrafast scaling laws with a saturated flux-linkage and loss model. The scalable model is used for the fast and accurate calculation of efficiency/loss maps and can also be used for drive cycle analysis including the calculation of energy consumption. It is verified by comparison with an existing state-of-the-art efficiency map and drive cycle analysis software. Additionally, an experimental verification of a saturated flux-linkage and loss model is presented. The additional possible usage of the scalable model is to find the optimal size of a scaled machine in order to meet the drive cycle performance and requirements of a traction motor. [ABSTRACT FROM AUTHOR]

In this paper, the influence of saturation and cross-coupling effects on the copper loss minimization for synchronous machines with strong saliencies, especially the permanent-magnet-assisted synchronous reluctance machines and reluctance synchronous machines are analyzed. It is shown that state-of-the-art methods for saturation consideration through the absolute inductances fail for these machines. A novel method for maximum torque per ampere estimation, which includes the consideration of these effects through the use of differential inductances, is proposed and its effectiveness is shown through finite-element analysis and experiments. [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]

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]

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 the recent years, the use of model predictive control in electrical drives has been widely reported both theoretically and experimentally. Predictive torque control has been developed to control induction motor drives, allowing high performance and fast dynamics. However, the optimization used in predictive torque control is based on a single cost function minimization, where control objectives are merged by using weighting factors. The selection of these scalar factors is achieved through offline and online search methods and they are heavily dependent on the system parameters. To avoid this drawback, a multiobjective fuzzy predictive torque control is presented. The proposed strategy replaces the minimization of a scalar cost function with a multiobjective optimization using fuzzy decision making. Experimental implementation is presented to validate the performance of the proposed control scheme. [ABSTRACT FROM AUTHOR]

After designing and optimizing an electric machine, efficiency maps are needed to predict a vehicle’s performance in a dynamic simulation. Calculating efficiencies at various torque and speed points, however, requires prior knowledge of the input excitation conditions, such as the current magnitude and advance angle, in an electromagnetic finite-element analysis simulation. Hence, this paper derives and uses nonlinear motor control equations (MTPA, FW, MTPV) in the study of efficiency map calculation while accounting for both saturation and cross-coupling effects. Two synchronous ac motors are considered in this paper, including the 2010 Prius IPM and a PM-assisted synchronous reluctance machine, with all procedure steps outlined in detail. [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]

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]

Servo motor drives generally consist of current, velocity, and position control loops. Tuning these controllers to achieve satisfactory and consistent dynamic responses is crucial. In this paper, a parameter identification and autotuning scheme for permanent-magnet ac servo motor drives is presented. Motor electrical parameters such as resistance and inductances were identified first for current control loop tuning. The torque constant and mechanical parameters were then identified for velocity and position loop tuning. The experimental results verified that the proposed scheme can estimate parameters accurately and within a short time. In addition, the system tuned by the proposed scheme was consistent with the desired dynamic performance. [ABSTRACT FROM PUBLISHER]

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 presents an improved fuzzy logic controller (FLC) for a permanent magnet synchronous motor (PMSM) for high performance industrial drive applications. The performance of the PMSM using proportional plus integral (PI) controllers and general fuzzy controllers are poor under load disturbances and transient conditions. The FLC is developed to have a smaller computational burden which makes it suitable for real time implementation, particularly at constant speed operating conditions. Hybrid control has the advantage of integrating a superiority of two or more control techniques for better control performances. A fuzzy controller offers better speed responses for startup and large speed errors. If the nature of the load torque is varied, the steady state speed error of the PMSM drive with an FLC becomes significant. To enhance the performance of the system, a new control method, hybrid fuzzy PI control and accelerated fuzzy PI control is proposed. The effectiveness of the proposed method is verified by a simulation based on MATLAB. The proposed hybrid fuzzy controller has good adaptability over load toque variation and can maintain constant speed. [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]

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]

The optimal drive current can reduce both the torque ripple and power loss in driving the permanent magnetic (PM) AC motor. This paper presents an analytical model for calculating the optimal drive current of the PMAC motor with surface mount PM rotor. Both the motors with and without the neutral line are analyzed. Theoretical analysis shows that, when the back-emf of the windings contains triple order harmonics, the neutral line of the motor can let the optimal drive current be different from the one without the neutral line, and it can also make the optimal drive current be more effective in the loss and torque ripple reduction. Two spindle motors are used in the analysis to show the influences of the optimal model presented. [ABSTRACT FROM PUBLISHER]

This paper investigates the importance of modeling steel B/H curves accurately, well into saturation, when simulating induction motors that are run into saturation (such as in variable-speed vehicular drives that use a wide field weakening region). Most steels are only tested just beyond the knee point which is insufficient without correct extrapolation. The results show, for a particular example, a 15% increase in line current and 4.2% reduction in torque when a good extrapolation is used and compared to a poor B/H curve. [ABSTRACT FROM AUTHOR]

This paper deals with the ac–dc interface conversion in grid-connected wind energy conversion systems based on modular permanent-magnet synchronous generators. In particular, some solutions based on diode rectifiers are extensively analyzed as for the waveforms, the efficiency, and the torque ripple, by considering several connections, which are allowed by the inherent modularity of the considered generators. Rectifier schemes with a high number of pulses can be easily realized without using special shifter transformers so that these solutions can be attractive for low- and medium-power applications. [ABSTRACT FROM PUBLISHER]

In rotating electrical machines, the air-gap magnetic field causes radial forces on the stator core physically based on the Maxwell stress. These radial force waves do not contribute to the torque generation of the machine but may lead to dangerous vibrations. This problem must be especially researched when designing salient pole synchronous machines with a high number of poles and fractional slot windings. At full load operation, the stator winding magnetomotive force (MMF), the stator tooth ripple effects, the saliency of the rotor poles, the induced currents in the damper winding, and the field winding MMF generate a set of harmonic field waves circulating around the air gap. The waves interact by modulation effects and therefore create different magnetic force wave modes. This paper presents an analytical computation model for force waves and compares results with finite-element calculations as well as measurements. Attention is paid to tooth ripple phenomena and reduction of parasitic forces with nonstandard stator winding phase belt distributions. [ABSTRACT FROM PUBLISHER]

For medium-voltage drives, model predictive direct torque control (MPDTC) significantly reduces the switching losses and/or the harmonic distortions of the torque and stator currents, when compared to standard schemes, such as direct torque control or pulse width modulation. Extending the prediction horizon in MPDTC further improves the performance. At the same time, the computational burden is greatly increased due to the combinatorial explosion of the number of admissible switching sequences. Adopting techniques from mathematical programming, most notably branch and bound, the number of switching sequences explored can be significantly reduced by discarding suboptimal sequences. This reduces the computation time by an order of magnitude, enabling MPDTC with long prediction horizons to be executed on today’s available hardware. [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]

In this article, the control technique of an AC variable-speed drive is presented using a modified direct torque control method. The AC motor of the drive is an induction motor, and the modified scheme of the direct torque control uses the space vector modulation technique to create the switching pattern of the inverter. The steady state of operation is investigated in depth as well as the dynamic performance of the system. The results of this modified control scheme are compared to the corresponding results of the classical direct torque control method, leading to the conclusion that the modified scheme is more robust and smoother in comparison to the classical one. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response. [ABSTRACT FROM AUTHOR]

Due to their robust structure, low and constant starting current, constant torque, and smooth and noiseless operation, small- and medium-sized power rating hysteresis motors are commonly employed in high-speed applications. However, hysteresis motors, in general, have a comparatively low power factor, efficiency, and torque density. In this article, a new structure, the coreless dual-rotor disc hysteresis motor, is introduced. Electromagnetic field analysis of the machine is performed, and its steady-state equivalent circuit is deduced. An algorithm employed in a computer simulation predicts the operating characteristics of the new machine. In comparison with common hysteresis machines, the superiority of the coreless dual-rotor disc hysteresis motor in regards to efficiency and power factor is revealed. Moreover, a sensitivity analysis is accomplished, and impacts of some structural parameters on the performance of the machine are illustrated. Simulation and a few experimental results for a prototype machine are given, and these validate the equivalent circuit and proposed model of the coreless dual-rotor disc hysteresis motor. [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 the results of an investigation into suitable torque control schemes for an electric vehicle application. The electric vehicle drive train consists of rewound induction motors and a three-level IGBT inverter switching at 10kHz. The schemes investigated are Direct Torque Control DTC with two-level IGBT inverter, and DTC with threelevel IGBT. The results of Matlab- Simulink simulations and a comparison between the control schemes are presented. It is found that the DTC using three-level IGBT scheme is best for this application. [ABSTRACT FROM AUTHOR]

An optimal design procedure is proposed to effectively reduce the torque ripple by optimizing the rotor pole shape of the spoke-type IPMSM with concentrated winding. The procedure is composed of two steps. In step 1, the steepest descent method (SDM) is used with only two design variables to rapidly approach the optimal shape. From the near optimal rotor shape as a result of the step 1, the design variables are reselected, and the drawing spline curves are utilized to explain more complex shape with the Kriging model in step 2. By using an optimal design procedure, we show that the optimized rotor pole shape of the spoke-type IPMSM effectively reduces the torque ripple while still maintaining the average torque. [ABSTRACT FROM AUTHOR]

Field aligned starting (FAS) is a technique for starting three-phase cage induction motors on either three-phase or single-phase supply lines under varying load conditions with minimal inrush currents. The technique starts the motor independent of the mains supply with a high transient torque before connecting the spinning motor to the mains. It is imperative to the operation of FAS that the spinning motor be connected to the mains at the correct time. Incorrectly timed mains connection can result in negative transient torques with the severity to slow, or possibly stall the already started motor. As the implementation of FAS is not possible without a predictive mechanism by which the correct moment of mains connection can be found in advance, this paper proposes a simple, low cost, yet effective self-calibrating method which ensures that the timing of the mains connection is correct under all starting conditions. Critical issues vital to a successful self-calibration under transient and varying starting conditions are investigated and presented with both experimental and simulated results to show that self-calibration is an indispensable part of FAS technique. [ABSTRACT FROM AUTHOR]

A novel direct torque and flux controlled interior permanent magnet synchronous motor (IPMSM) drive using an adaptive backstepping technique is presented. Closed-loop regulation of the speed, torque and stator flux linkage is achieved by a non-linear controller. Using Lyapunov analysis, the stability of the controller is guaranteed. The reference voltage vectors are generated by a space vector modulation (SVM) unit, which replaces the switching table in the conventional direct torque control (DTC) scheme. While retaining its main advantages, the proposed backstepping controller features reduced torque and flux ripples as compared to the classical DTC. On the one hand, a comparison with the proportional–integral (PI) direct torque and flux control (DTFC) scheme shows that the proposed approach is superior. Experimental results confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Hysteresis motors are exciterless and brushless machines with outstanding characteristics such as constant torque and speed, robust structure, low and constant starting current and smooth operation. On the contrary, hysteresis machines have some usage limitations such as low power factor, efficiency and torque density. Comparatively, the low efficiency of common hysteresis motors is mostly related to the parasitic losses generated by the slots. In general, closed or semi-closed slots are employed in the hysteresis machines to reduce the slotting effects and parasitic losses. A new slotless hysteresis motor is introduced. This structure with singular performance is named ‘slotless dual-rotor discs hysteresis motor’ (SDDHM). The capability of being fabricated as a cascade or multi-stack structure, plus the easy manufacturing process and high torque density and efficiency are some advantages of the proposed machine. A field analysis yielding to an equivalent circuit for the steady-state operating condition is presented. All elements of the equivalent circuit are formulated based on design parameters. The simulation of a prototype machine is given and its excellent performance is illustrated. Simulation results are compared with those of the experiment and this validates the proposed model. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with modeling and performance analysis of the voltage/frequency (V/f) control of induction motor drives. The V/f control, which realizes a low cost and simple design, is advantageous in the middle to high-speed range. Its torque response depends on the electrical time constant of the motor and adjustments of the control parameters are not need. Therefore, V/f control of induction motor is carried out. Space vector pulse width modulation is used for controlling the motor because of including minimum harmonics according to the other PWM techniques. Proportional Integral (PI) controller is used to control speed of induction motor. In this work, optimization of PI coefficients is carried out by Ziegler-Nichols model and Genetic-Adaptive Neuro-Fuzzy Inference System (ANFIS) model. These controllers are applied to drive system with 0.55kW induction motor. A digital signal processor controller (dsPIC30F6010) is used to carry out control applications. The proposed method is compared Ziegler-Nichols model. Experimental results show the effectiveness of the proposed control method. [Copyright &y& Elsevier]