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Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a new energy-optimized brushless DC motor (BLDCM) control algorithm is designed to enhance the system response during dynamic period for automotive applications. In the conventional sensor-based control, the reliability of the system is decreased with additional components and increased maintenance. Generally, the motor input voltage is sensed for the conventional BLDCM which is the widely used sensor-based control, using this method an accurate rotor position is not achieved at lower motor speeds. To improve the rotor position measurement, an observer-based state is added in the proposed sensorless-based BLDCM system. The proposed sensorless observer-based energy-optimized design is verified in MATLAB/Simulink for the BLDC wiper motor for automotive application. The observed results in MATLAB/Simulink validate the efficacy of the observer-based state estimation technique in terms of rotor position estimation and hence improved the dynamic performance of the BLDCM drive system. [ABSTRACT FROM AUTHOR]

In this article, the influence of trapezoidal magnetization method on cogging torque of permanent magnet motor is studied. First, the structure is analyzed by analytical method to explain its mechanism of reducing cogging torque. Then, in order to verify the effectiveness of the formula, a six-slot four-pole motor is introduced for finite element analysis. Through comparison of the original structure motor, the magnet skew structure motor, and the trapezoidal magnetic pole structure motor, it demonstrates that the trapezoidal magnetic pole structure motor can effectively reduce the Cogging torque and does not produce additional axial electromagnetic force. Finally, a magnetizing fixture with a trapezoidal magnetic pole structure is made to magnetize the magnetic ring. The magnetized magnetic ring is installed on the motor, and the Cogging torque, Back EMF, etc., are tested. The test results are in good agreement with the simulation results. This method can be used to optimize the cogging torque of the permanent magnet motor.

Nowadays the efficient use of energy is a major issue in applications such as electric vehicles. However, there are some phenomena that affect electric vehicle performance. One of those phenomena is the torque ripple of electric motors, which interferes with traction and the suspension system (causing vibration that stresses this system), and it can also introduce electric current harmonics into the battery, reducing its life, since torque ripple is partly a consequence of non-sinusoidal back EMF. For those reasons this is a topic worth investigating. The torque ripple of permanent magnets (PM) motors can be reduced in design or through control. Since control techniques have been reviewed and design methods have not, this paper presents a comparison of several design techniques to reduce torque ripple by different approaches and categorize them to show the characteristics of each group. A discussion is then made about the advantages and disadvantages of the designs, in general, as well as some comments about the missing, but important information, in the papers, such as the effects on efficiency. The study shows that a combination of methods provide the best results, although it complicates fabrication and suggests that this is a promising line of future investigation on torque ripple reduction methods.

In this paper, a fault-tolerant three-phase induction drive based on field-oriented control is studied, and an analytical approach is proposed to elucidate the limitations of FOC in flux-torque regulation from the controller perspective. With an open-phase fault, the disturbance terms appear in the controller reference frame and degrade the controller performance when operating in a d-q plane with DC quantities. In addition, the hardware reconfiguration, which is essential to operate faulted three-phase drives, causes substantial change in the way the control parameters vd, vq are reflected onto the machine terminals. An accurate understanding of the feedforward term, by considering the open-phase fault and the hardware modifications, is provided to re-enable the FOC in presence of an open-phase fault. Furthermore, the concept of feedforward term derivation is generically extended to cover multiphase induction drives encountering an open-phase fault whereby no hardware reconfiguration is intended. The proposed method is explained based on a symmetrical six-phase induction and can be extended to drives with a higher number of phases. The effectiveness of the proposed derivation method, which is required to form a feedforward fault-tolerant controller, is verified and compared through the simulation and experiment, ensuring smooth operation in postfault mode. [ABSTRACT FROM AUTHOR]

Nowadays the efficient use of energy is a major issue in applications such as electric vehicles. However, there are some phenomena that affect electric vehicle performance. One of those phenomena is the torque ripple of electric motors, which interferes with traction and the suspension system (causing vibration that stresses this system), and it can also introduce electric current harmonics into the battery, reducing its life, since torque ripple is partly a consequence of non-sinusoidal back EMF. For those reasons this is a topic worth investigating. The torque ripple of permanent magnets (PM) motors can be reduced in design or through control. Since control techniques have been reviewed and design methods have not, this paper presents a comparison of several design techniques to reduce torque ripple by different approaches and categorize them to show the characteristics of each group. A discussion is then made about the advantages and disadvantages of the designs, in general, as well as some comments about the missing, but important information, in the papers, such as the effects on efficiency. The study shows that a combination of methods provide the best results, although it complicates fabrication and suggests that this is a promising line of future investigation on torque ripple reduction methods. [ABSTRACT FROM AUTHOR]

This study proposes 1D modeling that considers the noise and vibration of a vehicle window-brushed DC motor. The electrical and mechanical components of the brush DC motor are included, creating a model that considers noise and vibration. The model has a back electromagnetic force (EMF) including vibration components and is constructed based on an electric circuit and transfer functions. To ensure the reliability of the model, the back EMF, noise, and vibration experiment environment of the brushed DC motor were configured. The measured back EMF was applied to the model, and it was confirmed that the simulation results of the model were consistent with the measured noise and vibrations. [ABSTRACT FROM AUTHOR]

Aiming to design a generator with high reliability, high efficiency, and especially a constant output voltage over a wide speed range for hybrid electric vehicles (HEVs), this paper proposes a novel topology of a hybrid excitation doubly salient generator with separate windings (HEDSGSW). The topology herein utilizes a hybrid excitation type of PMs and DC windings to generate parallel magnetic circuits. In addition, PMs are embedded in the magnetic bridge to insulate the excitation windings with armature windings. This design can achieve compactness, efficiency, and especially constant output capability over a wide speed range. The geometry and flux regulation principles, including magnetic flux circuits, are elaborated. After comparing three power generation modes, the most suitable mode, namely, the doubly salient generation 2 (DSG2) mode, is confirmed to ensure a stable voltage output performance. Then, considering the non-uniformity effect of the stator and rotor slots, the no-load back electromotive force (EMF) expressions are derived based on the EMF to air-gap relative permeance method. Furthermore, a 1 kW HEDSGSW FEA model, with an output voltage of 42 V and a rated speed of 6000 rpm, is built to demonstrate the effectiveness of the proposed method. Finally, the operating properties of the HEDSGSW, such as no-load characteristics and adjustment characteristics, are analyzed to further verify the rationality of its magnetic flux circuit and the flexibility of the excitation regulation capability. [ABSTRACT FROM AUTHOR]

Permanent Magnet (PM) machines are widely used due to their low cost, lightweight, small size, and better operating efficiency. Axial Flux Permanent Magnet (AFPM) machines are famous for low-speed applications with good efficiency. These machines are used in elevators, wind power production, and electric vehicles. In this paper, two single stack AFPM machines with air gap and without air gap are designed using the Diameter to Length (D²L) method. Various parameters are calculated with this approach. Power, back emf, coil flux, and flux density are the parameters that are analyzed. Moreover, it was observed that power fluctuates in single stack AFPM machines without air gap and power quality issue is taken into account. Apart from this, balance voltages are observed in both machines, while magnetic flux density decreases in machines with air gaps and enhances without air gaps. 'SolidWorks' is used for designing purposes and then the JMAG designer tool is also used to perform analysis using the Finite Element Method (FEM). [ABSTRACT FROM AUTHOR]

In high performance applications, LC filter usually is added to power converter for optimizing the output current ripple characteristics of the system. However, the LCL link composed of LC filter and resistor-inductance load causes the resonance, which leads to the traditional closed-loop not appropriate to be applied directly. Consequently, the active damping compensation method based on harmonic current is considered to suppress the resonance, and the suppression effects of different damping parameters on the resonant peak are compared and analyzed. Moreover, back EMF treated as a nonlinear disturbance affects the accuracy of current. Therefore, the current harmonic suppression method based on feedforward control for resonant pole-based dual buck soft-switching converter (RPDBSC) is presented, and the current suppression method of feedforward control is analyzed by the decoupling control model of bias current. This paper focuses on the improvement of the closed-loop control strategy for high precision current converters, and the effectiveness of the proposed method is verified by simulation and experiment.

To reduce the torque ripple, this study investigates the effect of different slot/pole ratios and air gaps on the torque ripple of the motor. Under the same size, same speed, and the same excitation, the performance analysis of the electric excitation concentrated winding motor with 12/10, 18/10, 30/10 is carried out. First, the finite element analysis of the motors with different slot/pole ratios is performed and the influence of the uniformity of the air gap of the motors on the cogging torque is comparatively analyzed. Through comparison, it is found that an appropriate slot/pole ratio can reduce cogging torque and the harmonic content of back EMF, and from the perspective of cogging torque, fractional slot motors are lower than integer slot motors. The use of non-uniform air gap can reduce the content of air gap magnetic density harmonics, therefore further reducing cogging torque and torque ripple. After finite element calculation, the inductance of these three kinds of motors and their influence on torque are analyzed. Finally, it is found that the non-uniform air gap has a more obvious effect on reducing the torque ripple of the motor. The torque ripple percentage of the 12/10 motor has been reduced from 10.6% to 4.2%. [ABSTRACT FROM AUTHOR]

In this study, a novel variable gain sliding mode observer is proposed to eliminate the chattering of traditional sliding mode observer and the phase delay of rotor position estimation. The designed sliding mode gain can vary with the back EMF value, and the back EMF observer, instead of the low-pass filter, is used to reduce the high frequency signal and chattering of the back EMF estimation value. The mathematical model of position sensorless control system is established, and the novel sliding mode observer is compared with the traditional sliding mode observer. The results show that the error of the new sliding film observer speed in steady state, acceleration and loading conditions is significantly reduced, which proves that the proposed new sliding mode observer has smaller chattering and higher accuracy. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a fault-tolerant three-phase induction drive based on field-oriented control is studied, and an analytical approach is proposed to elucidate the limitations of FOC in flux-torque regulation from the controller perspective. With an open-phase fault, the disturbance terms appear in the controller reference frame and degrade the controller performance when operating in a d-q plane with DC quantities. In addition, the hardware reconfiguration, which is essential to operate faulted three-phase drives, causes substantial change in the way the control parameters vd, vq are reflected onto the machine terminals. An accurate understanding of the feedforward term, by considering the open-phase fault and the hardware modifications, is provided to re-enable the FOC in presence of an open-phase fault. Furthermore, the concept of feedforward term derivation is generically extended to cover multiphase induction drives encountering an open-phase fault whereby no hardware reconfiguration is intended. The proposed method is explained based on a symmetrical six-phase induction and can be extended to drives with a higher number of phases. The effectiveness of the proposed derivation method, which is required to form a feedforward fault-tolerant controller, is verified and compared through the simulation and experiment, ensuring smooth operation in postfault mode.

The aim of this paper is to present the optimal design process and an optimized model for a discontinuous armature arrangement permanent magnet linear synchronous motor (PMLSM). The stator tooth shapes are optimized to reduce detent force. When the shape of the stator is changed to reduce the detent force, the saturation magnetic flux density and the back electromotive force characteristics change. Multi-objective optimization is used to search for the local lowest point that can improve the detent force, saturation magnetic flux density, and back EMF characteristics. To reduce the detent force generated at the outlet edge, a trapezoidal auxiliary tooth was installed and the performance was analyzed. The experiment's response surface methodology is used as an optimization method and all the experimental samples are obtained from finite-element analysis. The validity of this method is verified by comparing the optimized FEA model to the initial FEA model. [ABSTRACT FROM AUTHOR]

This study proposes 1D modeling that considers the noise and vibration of a vehicle window-brushed DC motor. The electrical and mechanical components of the brush DC motor are included, creating a model that considers noise and vibration. The model has a back electromagnetic force (EMF) including vibration components and is constructed based on an electric circuit and transfer functions. To ensure the reliability of the model, the back EMF, noise, and vibration experiment environment of the brushed DC motor were configured. The measured back EMF was applied to the model, and it was confirmed that the simulation results of the model were consistent with the measured noise and vibrations.

Aiming to design a generator with high reliability, high efficiency, and especially a constant output voltage over a wide speed range for hybrid electric vehicles (HEVs), this paper proposes a novel topology of a hybrid excitation doubly salient generator with separate windings (HEDSGSW). The topology herein utilizes a hybrid excitation type of PMs and DC windings to generate parallel magnetic circuits. In addition, PMs are embedded in the magnetic bridge to insulate the excitation windings with armature windings. This design can achieve compactness, efficiency, and especially constant output capability over a wide speed range. The geometry and flux regulation principles, including magnetic flux circuits, are elaborated. After comparing three power generation modes, the most suitable mode, namely, the doubly salient generation 2 (DSG2) mode, is confirmed to ensure a stable voltage output performance. Then, considering the non-uniformity effect of the stator and rotor slots, the no-load back electromotive force (EMF) expressions are derived based on the EMF to air-gap relative permeance method. Furthermore, a 1 kW HEDSGSW FEA model, with an output voltage of 42 V and a rated speed of 6000 rpm, is built to demonstrate the effectiveness of the proposed method. Finally, the operating properties of the HEDSGSW, such as no-load characteristics and adjustment characteristics, are analyzed to further verify the rationality of its magnetic flux circuit and the flexibility of the excitation regulation capability.

Sensors of any kind contribute to extra space and electronics when they are used in any application. Besides, the sensor noise also has the effect of altering the overall gain of the system. This is more prevalent in non-linear systems like motor control. In applications which have strict space constraints like Electric vehicles, the use of sensors must be optimized, which, in turn, gave rise to many sensorless state estimation strategies. This paper proposes a novel sensorless control technique for brushless direct current (BLDC) motor used in electric vehicle applications. The concept of sensorless control in BLDC Motor drive eliminates the hall-effect position sensor, thereby giving better performance and improves the robustness of the overall drive system. The main objective of this work is to estimate the position of the motor at standstill condition using stator saturation effect concerning the rotor, accelerate the motor from standstill so that enough back EMF is generated. This acceleration technique speeds up the motor to a stage where a self-actuating control mechanism is used to generate control signals with back EMF or line voltages. The motor can be started with a load, which is a significant constraint for electric vehicle application. The proposed method will avoid the reverse rotation of the motor. The proposed work is simulated in Matlab/Simulink software, and results obtained show that it works well under dynamic conditions of starting, acceleration and load switching. The hardware setup of the proposed work is developed using the TMS320F2812 DSP processor. Simulation and experimental results validate the effectiveness of the proposed work for electric vehicle application. [ABSTRACT FROM AUTHOR]

This paper proposed an improved sensorless control strategy for ship electric propulsion which bases on I/f control and back electromotive force integral (EMF), suppressing the speed fluctuation during algorithm switching, improving the flux estimation accuracy of internal permanent magnet synchronous motors (IPMSMs) and achieving the stable operation of the motor. Firstly, this strategy was adopted for controlling the stator current during the switching process to improve speed fluctuation. Then, a simple flux estimation method is presented by rewriting the mathematical model of IPMSM. To achieve the result which overcomes the problem of flux estimation and current measurement errors and improved LPF was developed which solved the phase delay and DC-offset problem of flux estimation. Finally, the propeller load platform is under construction to verify the effectiveness of the control strategy. Experimental results show that the system based on this method works smoothly and it has better speed tracking performance.

Three different radial flux ironless brushless dc (BLdc) motor types (motors without inner back-iron of the rotor, with inner back-iron of the rotor, and with dual-rotor) are investigated and compared in this paper. The magnetic field distribution, back electromagnetic force (EMF), axial end effect, and torque characteristics are investigated. First, the relationship between the magnetic field distribution and the motor size and pole pairs is investigated. It shows that the two parameters are not independent of each other and the magnetic field distribution is mainly related with the arc length of the permanent magnets. Second, the radial magnetic flux density in the coil regions of the three ironless BLdc motors is calculated and an evaluation factor is proposed to show the quality of the magnetic field distribution. Third, the influence of the winding configuration and the combination of slot and pole number on EMF is analyzed, and the corresponding evaluation factors are calculated and tabulated. Then, the axial end effect of the three ironless BLdc motors considering the fringe effect is investigated and compared. Next, the torque characteristics at full load and rated speed are studied for the three types of motors. Finally, the ironless BLdc motor without back-iron of the rotor is manufactured and tested. The experimental results are in good agreement with the finite-element method.

This paper presents a novel predictive direct torque control (PDTC) for permanent magnet synchronous motors (PMSMs) using the zero voltage vector and a selected voltage vector from the 12 available voltage vectors. The 12 voltage vectors consist of 6 effective voltage vectors and 6 combinational voltage vectors to improve control performance. To select the optimum voltage vector for each of the operating conditions, the predictive flux and torque at the zero voltage vector that consider both the back EMF (electromotive force) and the decoupling effect, are used to determine the voltage vector. The PWM (pulse width modulation) duty ratio to reduce torque and flux ripples can be determined by three factors: the reference flux and torque using a zero voltage vector, the predictive flux and torque using a zero voltage vector, and the predictive flux and torque using a selected voltage vector. Due to the linear ratio of the predictive torque and the flux errors in the next sampling, the proper duty ratio to reduce ripples can be easily obtained by the zero voltage and selected voltage vectors. To further reduce ripples, an additional 6 combinational voltage vectors are used, which are the result of combining the duty ratios of the adjacent two effective voltage vectors. Furthermore, a multi-level flux hysteresis band is designed to select the optimal voltage vector according to the operating conditions among the available 12 voltage vectors. The proposed PDTC scheme is verified by simulation and experiments using a practical 1 [kW] PMSM. In both the simulation and experiments results, the proposed PDTC scheme shows advanced control performance with reduced torque and flux ripples and reduced steady state error. [ABSTRACT FROM AUTHOR]

Electric drive without electrical and mechanical sensors is the critical obligation in most of the industrial applications due to its user-friendly hardware, lower maintenance, low cost, more reliability, etc. To replace the sensors, a number of schemes are employed, which extract the sensored data from the known parameters by using the machine model and/or its mechanical structure. In the past few years, researchers developed a variety of sensorless schemes for various applications by using different drives and their control algorithms to make it vigorous in any electrical, mechanical, and physical environments. In this paper, more than 275 publications were critically reviewed and the technological progression was presented for the sensorless control of electric drives by various motor control techniques. In addition to this, the review of sensorless AC drive system and its application was also studied and presented. [ABSTRACT FROM AUTHOR]

In this paper, an effective scheme of on-load startup with reduced current has been proposed for BLDC motor and the steady as well as dynamic performance in all four quadrants was verified. Hysteresis band-limited back EMF noise provides the starting pulses, the frequency of which depends on the threshold factor in speed proportional threshold. Scheme is quite fast, comparatively to the state-of-the art schemes of startup and less complex than time-consuming initial position detection (IPD) algorithm. Second-order least P th-norm infinite impulse response (IIR) digital low pass filter realized in MATLAB/Simulink has been used for extraction of line-to line back EMF from line-to-line terminal voltages measured with two voltage sensors. Proposed filter has wide flexibility of online variation of cut-off frequency, gain and phase without any circuit-based modification due to variability of filter coefficients. This enables the smooth filtering with minimized phase delay in low speed range irrespective of any duty cycle and PWM frequency. Linear compensation of phase error or phase advancement for desired current profile can easily be achieved by the varying the threshold factor. In this experiment, the threshold factor of 1/1460 has been found most suitable for smooth sensorless startup without jerk, vibration and reverse rotation, as the motor operates in advanced mode with this value. First, the performance of Hall sensor-based drive was studied using open loop variable duty cycle speed control. The controller was designed in MATLAB/Simulink platform and implemented using TMS320F28069M DSP control stick with Code composer Studio V5. Later on, a complete controller for proposed sensorless scheme was developed in MATLAB/Simulink environment and was implemented using NI-PCI6221 Controller installed in PC. The proposed sensorless drive has been found capable of operating at very low speed of 50 rpm in voltage control mode and 85 rpm in current chopping PWM mode. Approximately 85 ms less time was taken by sensorless drive to reach the same speed when compared with Hall-based control for identical loading. Also less overshoots during startup was observed. Overlap time of 0.05 ms between phase currents has been achieved during commutation period. [ABSTRACT FROM AUTHOR]

In mass production, manufacturing tolerances are unavoidably generated between the core and permanent magnet. Furthermore, it is necessary to improve the tolerance effect by changing the shape of the motor because the back electromotive force (EMF) and cogging torque are influenced by manufacturing tolerances. In this study, Taguchi robust design is applied to an air blower motor that is used to circulate the air in the fuel cell stack of an electric vehicle. As the widely used Taguchi method could not achieve a multi‐response, a multi‐response signal‐to‐noise ratio based on the Taguchi robust design is employed to consider the back EMF and cogging torque. Finally, an optimum shape is determined for selecting the appropriate combination of control factors in the robust design, and the average and standard deviation of the back EMF and the cogging torque are improved. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the optimal design process and an optimized model for a discontinuous armature arrangement permanent magnet linear synchronous motor (PMLSM). The stator tooth shapes are optimized to reduce detent force. When the shape of the stator is changed to reduce the detent force, the saturation magnetic flux density and the back electromotive force characteristics change. Multi-objective optimization is used to search for the local lowest point that can improve the detent force, saturation magnetic flux density, and back EMF characteristics. To reduce the detent force generated at the outlet edge, a trapezoidal auxiliary tooth was installed and the performance was analyzed. The experiment’s response surface methodology is used as an optimization method and all the experimental samples are obtained from finite-element analysis. The validity of this method is verified by comparing the optimized FEA model to the initial FEA model.

Higher efficiency is always a desire for the electric machines researchers. One serious candidate is the axial flux permanent magnet motor to achieve that. These machines have advantages on power and torque density profile. This study aims to analyse the performances of the different rotor poles’ characteristics of the axial flux permanent magnet machines. The magnetic equivalent circuit designed and placed into the single gap axial flux permanent magnet machine to fathom the machine characteristic. The proposed rotors magnet poles are investigated in the view of the torque ripple reduction, back EMF waveforms and flux density distribution by using finite element analysis. Four different designs are compared. 3D analysis is used for FEA simulations. Torque ripple, back emf and magnetic flux distribution waveforms are obtained from the 3D FEA analysis. As a result, the proposed rotors are practicable and situated for higher performance.

This paper presents the developments of sensorless control of interior permanent magnet synchronous machine (IPMSM) for last 10 years, which could be divided into the past and the present for each 5 years. Several popular methods developed for last 10 years would be described and evaluated, and the limitations with the methods are discussed. In the past a concept extended EMF (EEMF) was introduced and it can model IPMSM as a non-salient motor, meaning that the representation of IPMSM in the estimated rotor reference frame would be much simpler and accurate. However, because it still relied on back EMF, standstill operation was impossible. And, the position control of IPMSM could not be achieved with EEMF concept. For sensorless drive, the high-frequency signal injection method exploiting inherent saliency of IPMSM has been continuously developed for last 10 years and applied to various industry fields, where torque control at standstill is essential. Its performance has been improved but there are still many problems to be solved. In the present, the square-wave signal injection at estimated d-axis has improved the control performance conspicuously. However, there are strong demands to improve the control performance of sensorless drive, yet. Based on the problems in the present, in this paper the possible developments of sensorless drive of IPMSM in next 5 years are enlightened as the future of sensorless control.

Induction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition.

Axial flux machines have positive sides on the power and torque density profile. However, the price of this profile is paid by the torque ripples and irregular magnetic flux density production. To gather higher efficiency, torque ripples should close to the zero and the stator side iron should be unsaturated. Torque ripples mainly occur due to the interaction between the rotor poles and the stator teeth. In this study, different rotor poles are investigated in contrast to stator magnetic flux density and the torque ripple effects. Since the components of the axial flux machines vary by the radius, analysis of the magnetic resources is more complicated. Thus, 3D-FEA (finite element analysis) is used to simulate the effects. The infrastructure of the characteristics which are obtained from the 3D-FEA analysis is built by the magnetic equivalent circuit (MAGEC) analysis to understand the relationships of the parameters. The principal goal of this research is a smoother distribution of the magnetic flux density and lower torque ripples. As the result, the implementations on the rotor poles have interesting influences on the torque ripple and flux density profiles. The MAGEC and 3D-FEA results validate each other. The torque ripple is reduced and the magnetic flux density is softened on AFPM irons. In conclusion, the proposed rotors have good impacts on the motor performance. [ABSTRACT FROM AUTHOR]

Higher efficiency on electric machines is the research goal of many studies. An example is the axial flux permanent magnet machines. These machines have some advantages like their watt/kg efficiency and torque density. This study aims to develop the performance characteristics of the axial flux permanent magnet machines. A new rotor magnet poles design in axial flux machines is suggested to mitigate the torque ripples. The method of stepping and shifting of the magnets is used. Two different designs are compared to verify the proposed approach. 3D finite element analysis is used for simulations. Torque ripple and back electromotive force waveforms are obtained from computer analysis. As a conclusion, the suggested method is found to be useable and mitigates the torque ripples. In addition to that, back EMF waveforms are turned to sinusoidal by the suggested design. [ABSTRACT FROM AUTHOR]

This paper aims to present a general and effective analytical approach to calculate the air gap flux density and the back electromotive force (EMF) of a flux-switching permanent magnet (FSPM) machine. The proposed analytical expression of the air gap flux density is based on an improved air gap permeance function considering the geometries of slotted stator core pieces and magnets between stator teeth as well as the salient rotor poles. The back EMF equation is accurately derived using the proposed air gap flux density equation expressed in terms of practical machine dimensions and thus it provides the key design factors as well as details of the back EMF production mechanism. To validate the proposed analytical expressions, they are applied to the case study of a 12-slot 10-pole FSPM machine, and the finite element analysis results confirm the analytical predictions. Besides, for the proposed analytical model, the effects of the machine’s geometries on back EMF characteristics are investigated. The investigation shows that the ratio of rotor slot opening to slot pitch has a significant effect on the back EMF, and its optimal value is suggested. The proposed equations also provide a mean to choose the slot and pole combinations to obtain a higher power density.

SUMMARY This paper proposes a new and simple torque-sensorless torque control method for permanent-magnet synchronous motors (PMSMs) with nonsinusoidal back EMF. The method suppresses the sixth and/or 12th harmonic torque ripples caused by the back EMF in a feedforward manner even at high speeds; it consists of two subordinate methods for compensation command generation and command-tracking current control. The first subordinate method generates compensation current commands to cancel the torque ripples based on a mathematical model of PMSMs. The second method controls the stator current to track a current command containing both fundamental and compensatory components. In conjunction with the current control, a dedicated disturbance observer that employs a digital speed-varying band-pass filter as a disturbance filter is also proposed. The effectiveness and usefulness of the proposed method were verified through extensive experiments. [ABSTRACT FROM AUTHOR]

In this paper, an analytical quasi three-dimensional method is used to model an axial flux permanent magnet (AFPM) machine with various eccentricities. AFPMmachines (AFPMMs) have various advantages but they are sensitive to geometrical imperfections for manufacturing aspect. The main aim of this paper is to propose a general analytical model to analyze the AFPMMs with various types of eccentricities. The radial and tangential magnetic flux densities in the air gap under healthy condition are obtained via combination of Maxwell's equations and Schwarz-Christoffel (SC) mapping firstly. Next, in order to investigate the eccentricities, equations for air gap length and radii are deduced. The back electromotive force (EMF) is calculated and compared with those from healthy condition and finite element (FE) analysis, respectively. The results show that the analytical predictions agree well with the FE results. Moreover, using this method has a significantly less time consuming than the 3D FM simulation process, which is a great advantage of this method. Finally, the analytical model is verified via experimental results. [ABSTRACT FROM AUTHOR]

Copyright of Automatika: Journal for Control, Measurement, Electronics, Computing & Communications is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Induction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition. [ABSTRACT FROM AUTHOR]