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This paper discusses systematic efficiency considering the efficiency of both a motor and airflow in an inverter-driven single-phase brushless direct-current (BLDC) motor with two different lamination designs for a cordless vacuum cleaner. In other words, multi-physical lamination design has to be conducted, and hence, the shape and placement of a whole electromagnetic structure are investigated in terms of a tradeoff between the electrical and mechanical efficiencies. In this paper, a single-phase BLDC motor for cordless vacuum cleaners is designed to satisfy starting and continuous torques by means of asymmetric air gap, and fluid analysis is performed to determine which shape of a single-phase BLDC motor has better system efficiency. The prototype of a single-phase BLDC motor has been tested, and the speed of the operation is ranged from 84468 r/min up to the rated speed of 100020 r/min. The motor efficiency of 94.7% has been measured to verify a good match with the estimated efficiency of 94.5%. [ABSTRACT FROM AUTHOR]

A new method for fast calculating the permanent magnet (PM) eddy current losses (ECLs) in interior PM synchronous machine caused by the high-frequency harmonic voltages (HFHVs) under pulsewidth modulation (PWM) voltage source inverter supply is proposed, by which time-consuming transient finite element analysis (FEA) is eliminated and the influence of the axial segmentation on the PM ECLs can be taken into consideration. The combination of the fixed differential permeability method and the linear frequency FEA is proposed to investigate the relationship between arbitrary HFHV and the corresponding PM ECL at different load conditions. The analytical model proposed in the previous published paper is used to describe this relationship quantitatively. Finally, the total PM ECLs at different load conditions can be calculated based on the fast Fourier transform results of the input PWM voltages. The relative errors between the total losses obtained with the proposed method and those with time-stepping FEA are within 21% at four typical load conditions, and the proposed method can reduce the computation time for one load condition to few minutes considering arbitrary PM axial segmentation. [ABSTRACT FROM AUTHOR]

In this paper, we develop and examine permanent magnet synchronous motors (PMSMs) by use of both stator and rotor cores made of nanocrystalline magnetic materials (NMMs). We report core loss properties of the PMSM with the NMM under inverter excitation. In addition, we compare core losses of the PMSM with conventional non-oriented (NO) steel sheets under inverter excitation to discuss the core loss characteristics of the NMM motor. In average, under inverter excitation, the reduction ratio in core loss of the PMSM made of NMM is about 60% as compared with the core loss of the PMSM with NO sheets. In particular, the average decrease obtained by using NMM rotor core instead of NO rotor core is about 30%. [ABSTRACT FROM AUTHOR]

This paper investigates both the fundamental and harmonic losses of permanent magnet synchronous motor (PMSM) in conjunction with inverter losses for a wide range of switching frequencies (SFs) and different direct-axis currents (Ids) under full power range. The effects of SFs and Ids on the total losses, including fundamental loss and harmonic loss in the windings and lamination core, conduction loss, and switching loss in IGBTs, are described through analytical models. Meanwhile, the loss models of the motor are modified and validated by the 2-D finite-element analysis. Furthermore, the efficiency improvement of the overall PMSM-inverter system for different operation conditions benefits from an artificial bee colony (ABC) algorithm proposed in this paper. The optimal SF and Id, in terms of PMSM-inverter overall efficiency, are preferred for every operation point, thanks to the proposed ABC and the precise calculation of losses. Experimental results validate the proposed methodology. [ABSTRACT FROM PUBLISHER]

This paper proposes a common-mode electromagnetic interference (CM-EMI) spectrum calculation method based on double Fourier series for photovoltaic (PV) inverters with chaotic sinusoidal pulsewidth modulation (CSPWM). In this paper, the CM-EMI of a single-phase PV inverter is first analyzed, and the equivalent circuit of the CM-EMI in the single-phase PV inverter is established, then the CSPWM is employed to suppress the CM-EMI in PV inverters. Moreover, the proposed EMI spectrum calculation method based on double Fourier series is applied in evaluating the CM-EMI spectrum of the single-phase PV inverter. Finally, the simulation and experimental results validate the EMI suppression effectiveness of the CSPWM and the correctness of the proposed EMI spectrum calculation method. Therefore, the proposed EMI spectrum calculation method provides a theoretical support for CSPWM to reduce EMI. [ABSTRACT FROM AUTHOR]

High-speed permanent magnet machines, supplied by pulsewidth modulation (PWM) voltage source inverters, operate with distorted stator currents. Harmonics present in these stator currents deteriorate the machine performance by generating losses. Mostly, these losses are following the machine design using a transient finite-element model. The precise measurement of these rotor eddy-current losses is extremely difficult, hence, only a few papers provide convincing comparisons between predictions and measurements. This paper presents a fast and precise analytical approach, verified with measurements, to consider rotor losses of machines, supplied by PWM voltages, already during the design procedure. [ABSTRACT FROM AUTHOR]

We calculate an iron loss attributed to semiconductors ON-voltages in an inverter circuit and reveal influence rate of the ON-voltages on whole iron loss. In our previous work, it has been revealed by inverter excitation that the ON-voltages make minor loops in magnetic hysteresis of magnetic material and the loops affect iron loss characteristics. In this paper, it is investigated by a factor analysis how much the on-voltage has an influence on iron loss, quantitatively. We separate whole iron loss caused in a non-oriented electrical steel sheet into three losses: loss by the ON-voltage, loss by fundamental component, and loss by inverter carrier. The rates of these losses are evaluated under several conditions of single-phase pulse width modulation inverter excitation, and the results show that the proportion of loss by ON-voltages is up to around 10% depending on inverter excitation parameter: fundamental frequency, carrier frequency, modulation index, and magnetic flux density. [ABSTRACT FROM PUBLISHER]

The effects of temperature-dependent material properties, including those of silicon steel and permanent magnet (PM) materials, on the design process of inverter-fed PM motors are investigated in this paper. The magnetization curves of these materials are measured experimentally at different temperatures and are imported into a finite-element package. Then, a statistical study of an integrated motor-drive system consisting of an interior PM motor connected to a space vector modulated inverter is performed by assigning four different temperatures and building a design space of various objectives including the integrated system efficiency, speed limits, motor startup quality, torque ripple, total harmonic distortion, and power factor as the geometrical dimensions are varied. The results reveal that incorporating the realistic material properties into the design process is essential. Moreover, different motor-drive performances have totally different variation rates as the material properties are changed. Finally, a set of optimal designs at different temperatures is proposed to show the effect of changing material properties. [ABSTRACT FROM AUTHOR]

Large amounts of harmonics are contained in the current as the motor is driven by pulse width modulation (PWM). Significant amounts of computing time are required to compute local flux density variation considering such current harmonics. Since the amplitudes of higher harmonics are significantly smaller than that of fundamental harmonic, flux density variations due to the higher harmonics are small, and the relationship between the field strength and flux density can be assumed to be linear. When the operating point of each element is known, flux density variations for the higher harmonics can be analyzed by linear finite-element analysis (FEA). This paper suggests a method to calculate flux density variations in the iron core while taking into considering PWM current harmonics. First, the operating point solution is obtained by nonlinear FEA, second each element is linearized. Then, the flux density for the PWM current is obtained through linear FEA. Finally, the obtained results are presented and compared with nonlinear FEA results for verification. [ABSTRACT FROM AUTHOR]

Recently, novel magnetic materials have been developed for high-efficiency and high power density electric motors. In addition, next-generation semiconductor devices, like silicon carbide (SiC) or gallium nitride (GaN), have been introduced for power converters due to their high-frequency operation. Therefore, high-frequency operation of new magnetic materials is possible when they are driven by GaN or SiC inverters. Nevertheless, iron loss characterization of magnetic materials when they are excited by high-frequency signals have not been conducted yet. This paper introduces the iron losses characterization of a magnetic material at high carrier frequency excitation using a GANFET inverter. This characterization was carried out by the experimental evaluation of iron losses at carrier frequencies from 5 to 500 kHz at different deadtimes. As a result of the measurements, iron losses seem to have a trend to increase at high carrier frequencies and large deadtimes. In addition, filtering is introduced and it seems to be an effective technique for reducing iron losses. [ABSTRACT FROM AUTHOR]

In this paper, the investigation is focused on the iron loss prediction for electrical machines fed by low switching frequency inverter. An improved iron loss model is developed after reviewing various existing iron loss models considering pulse-width modulation (PWM) influence. In order to validate the improved iron loss model, iron loss tests are carried out on an electrical machine. The predicted iron loss results match well with the measured results, which shows that the improved iron loss model is able to predict iron loss in electrical machine fed by an inverter. The comparison between the predicted iron losses with and without considering the PWM influence shows that the iron loss can be significantly increased due to the influence of PWM, especially when the switching frequency is low. [ABSTRACT FROM AUTHOR]

Recently, interior permanent magnet synchronous motor (IPMSM) is paying attention because of its high power density and efficiency by adopting permanent magnet. The IPMSM has two control methods: maximum torque per ampere (MTPA) control and flux weakening control. Generally, an MTPA control is applied to a continuous operating point, and in case of a startup point, input current is applied which satisfies required output torque. To control the IPMSM, the various types of inverters with current and voltage limitations are used. The motor cannot be operated if these limitations are not satisfied. This paper proposes a method to satisfy the current and voltage limitations of the inverter with two different operating points. By changing the control method of the rated operating point by a stack compensation method, the current and voltage limitations of the inverter can be satisfied at a startup operating point, where the input current in MTPA control at the continuous operating point cannot be satisfied. The proposed method is verified by a 2-D finite element analysis. [ABSTRACT FROM AUTHOR]

This paper provides new magnetic and electrical design guidelines for an integrated motor-drive system. Two significant design factors including the electric and magnetic loadings are targeted to address the issues associated with the combination of the motor and inverter performances. A set of new constraints is also introduced in terms of the magnetic, electrical and thermal limits of a field oriented controlled permanent magnet (PM) motor to highlight the corresponding design challenges. Moreover, the demagnetization proximity limit is incorporated to ensure a reliable and safe operation of the PM material. The results show that the magnetic and electrical requirements of an optimum integrated system are totally different from the optimum performances of either side of the system, i.e., the motor or the inverter. Finally, an efficiency/robustness trade-off is proposed and applied to the investigated motor-drive system to return a reliable and efficient design. [ABSTRACT FROM AUTHOR]

Applying the Jiles-Atherton (JA) model to simulate the dynamics of power electronics circuit is a challenge but very attractive since it is possible to carry out continuous simulation with only several input parameters. Although other methods such as the Preisach-model can result in approximate waveforms for such applications, it is still a far distance to reach exact ones to suit chaos and other high accuracy-requiring researches. In this paper, the JA model has been successfully applied to model the dynamics of resonant inverter for driving a nonlinear load: a fluorescent lamp. The circuit is driven by a high frequency square wave voltage source. A semi-theoretical fluorescent lamp model developed from HID lamp model is adopted in the modeling. The simulation waveforms of voltage across the lamp and current through it are close to those measured ones reported in the literature papers. [ABSTRACT FROM AUTHOR]

This paper presents the control method that inverter output keeps to linear to reference voltage of Synchronous Reluctance Motor (SynRM) using DC Link voltage Synthesis. This method is reduced torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for SynRM, the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. The Inverter output voltage cannot be displayed to linear about inverter reference voltage if Real DC Link voltage is different from DC Link voltage of PWM amplitude. Also, the over-modulation is linearity broken if reference voltage is out of range. Torque ripple generates the vibration and noise of a motor. This paper proposes the control method so that the torque ripple decreases and the linearity of inverter output keeps using the DC Link voltage Synthesis. The proposed control method is verified by computer simulation and experiment. [ABSTRACT FROM AUTHOR]

This paper deals with the detection of saturation in the magnetic core of a welding transformer which is a part of a middle-frequency direct current (MFDC) resistance spot welding system (RSWS). It consists of an input rectifier, which produces dc bus voltage, an inverter, a welding transformer, and a full-wave rectifier that is mounted on the output of a transformer. During normal RSWS operation welding transformer's magnetic core can become saturated due to the unbalanced resistances of both transformer secondary windings and different characteristics of output rectifier diodes, which causes current spikes and over-current protection switch-off of the entire system. In order to prevent saturation of the transformer magnetic. core, the RSWS control must detect that the magnetic core is approaching the saturated region. The aim of this paper is to present a reliable method for detection of magnetic core saturation that does not require an additional sensor. It is based on the artificial neural network (ANN). Its input is the measured primary current of the welding transformer. The applied ANN is trained to recognize the waveform of the current spikes in the primary current caused by the magnetic core saturation, which is used for magnetization level detection. [ABSTRACT FROM AUTHOR]

The development of high-power density electrical machines continues to accelerate, driven by military, transportation, and industrial needs to achieve more power in a smaller package. Higher speed electrical machines are a recognized path toward achieving higher power densities. Existing industry testing standards describe well-defined procedures for characterizing both synchronous and induction machines. However, these procedures are applicable primarily to fixed-frequency (usually 60 or 50 Hz) power supplies. As machine speeds increase well beyond the 3600-rpm limitation of 60-Hz machines, a need for performance testing at higher frequencies is emerging. An inverter power supply was used to conduct a complete series of tests on two induction motors (0.5 and 1.0 MW) with speeds up to ~5000 rpm. The use of a nonsinusoidal power supply with limited power output capability required the development of measurement techniques and testing strategies quite different than those typically used for 60/50 Hz testing. Instrumentation and techniques for measuring voltage, current, and power on harmonic rich waveforms with accuracies approaching 1% are described. Locked-rotor and breakdown torque tests typically require large kVA input to the motor, much higher than the rated load requirement. An inverter sized for the rated load requirements of the motor was adapted to perform locked-rotor and breakdown torque tests. Inverter drive protection features, such as anti-hunting and current limit that were built into the inverter had to be factored into the test planning and implementation. Test results are presented in two companion papers. This paper (Part 1) correlates test results with the results of an algorithmic induction motor analysis program. Part 2 presents the test results compared with a Matlab simulation program and also provides a comprehensive discussion of the instrumentation that was essential to achieve testing accuracy. Correlating test results with calculated values confirmed that the testing techniques developed during this testing program are useful for evaluating high-speed, high-power density electrical machinery. [ABSTRACT FROM AUTHOR]

This paper introduces the periodic carrier frequency modulation (PCFM) for permanent magnet synchronous motor (PMSM) drive systems so as to reduce the low-frequency electromagnetic interference (EMI). PMSMs are widely used in many applications and they are usually fed by pulsewidth modulation (PWM) inverters. The EMI of PMSM, which results from the switch of power device, generates undesirable effects on the control system. Therefore, it is of importance to reduce the EMI of PMSM. The common mode (CM) conducted EMI model of the PMSM drive system is constructed to investigate the CM voltage. The simulations and experiments of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to analyze the CM conducted EMI. The CM EMI spectra of PMSM fed by the FFPWM and PCFM with different spreading frequency widths are compared to explore the influence of PCFM on the CM conducted EMI. The regular patterns on PCFM in reducing the CM conducted EMI of PMSM drive systems are revealed. [ABSTRACT FROM AUTHOR]

To evaluate how magnetic properties of magnetic materials are influenced by power semiconductor properties in an inverter circuit, we propose and test a new numerical calculation method. This method combines an electrical circuit analysis for current–voltage properties of power semiconductors with a magnetic analysis based on a magnetic hysteresis model. Previous measurements on an inverter show that magnetic properties, such as B–H curves (B is the magnetic flux density and H is the magnetic field intensity) and iron losses, are affected by ON-voltages of power semiconductors. Those measurements motivate this paper. The magnetic hysteresis model used here is a novel approach that is based on physical thermodynamics theory and can capture the essence of physical magnetic phenomena. Calculations with the proposed method show that measured minor loops in B–H curves are well represented and calculated voltage waveforms properly capture ON-voltage effects. [ABSTRACT FROM AUTHOR]

In this paper, a novel calculation method of references on current amplitude and current angle of a vector inverter for an interior permanent magnet synchronous motor is proposed using FEM. For a vehicle application, the current information should be calculated effectively within the driving range while satisfying limitation value of battery voltage. Moreover, the parameters related to current and voltage information have nonlinear characteristics because of high power density of traction motor. FEM is used to calculate exact solution considering nonlinear characteristics. The proposed method for current references only uses several load angle curves of traction motor by FEM according to specified current values. By using load angle curves, the driving currents information for vector inverter can be calculated and interpolated effectively including field weakening region as well as constant torque region satisfying limitation of battery voltage. [ABSTRACT FROM AUTHOR]

This paper describes dynamic performance of a tubular linear actuator with Halbach array and mechanical spring driven by a pulse wide modulation inverter. By expressing mechanical components as motional impedance from a motion equation, this paper investigates the variation of not only active and reactive power dissipated in the actuator but also current and power factor for the actuator for various values of frequency and predicts theoretical resonant frequency. Finally, experimental results for dynamic characteristics such as current and stroke are presented for various values of frequency including resonant frequency. [ABSTRACT FROM AUTHOR]

This paper introduces a frequency-controlled low-voltage, high-current inverter power supply suitable for use in spot welders. The design of the proposed power supply was based on the fact that the voltage drop caused by leakage inductance in the transformer is proportional to the excitation frequency. In this power supply, the inverter frequency can be varied to easily control load current. This paper compares the reflux current effect when the transformer is operated in inverter control with operation using an AC sine wave. [ABSTRACT FROM AUTHOR]

In this paper, a numerical model using the finite-element (FE) method was used to predict the electromagnetic interference (EMI) generated by 325-V, 5-kW power inverter, supplying a variable three-phase load. A comparative analysis was performed to evaluate the effects of different switching patterns on the radiated and conducted EMI levels. An experimental setup was arranged to validate the simulation results. The proposed approach is suitable for prediction of radiated and conducted EMI generated by power converters. This helps reduce the post prototype EMC testing cost by minimizing redesign and modifications of final converter product. [ABSTRACT FROM AUTHOR]

In this paper, a new analytical methodology is proposed to estimate core losses in line-start and inverter-fed induction motors under rotor broken bars. This methodology can be utilized for different supply and load conditions. Core losses are precisely calculated taking into account the effects of nonsinusoidal distribution of the magnetic flux density due to bars breakage. Furthermore, increase of the stator current side-band components magnitude is considered to estimate Ohmic losses accurately. In order to calculate the above-mentioned losses, distribution of the magnetic flux density and stator currents of the induction motor is simulated using modified winding function method. In this modification, influence of nonlinear characteristics of the core materials is taken into account. Moreover, impacts of the spatial distribution of the stator windings, stator and rotor slots are considered. Two well known CV/F and direct torque control techniques are applied to the modeled motor and the aforementioned losses are calculated in the line-start, and inverter-fed modes. The simulation results are verified by the experimental results. [ABSTRACT FROM AUTHOR]

In hybrid and electric vehicles, passengers sit very close to an electric system of significant power, which means that they may be subjected to high electromagnetic fields. The hazards of long-term exposure to these fields must be taken into account when designing electric vehicles and their components. Among all the electric devices present in the power train, the electronic converter is the most difficult to analyze, given that it works with different frequencies. In this paper, a methodology to evaluate the magnetic field created by a power electronics converter is proposed. After a brief overview of the recommendations of electromagnetic fields exposure, the magnetic field produced by an inverter is analyzed using finite element techniques. The results obtained are compared to laboratory measurements, taken from a real inverter, in order to validate the model. Finally, results are used to draw some conclusions regarding vehicle design criteria and magnetic shielding efficiency. [ABSTRACT FROM AUTHOR]

It is important to inspect pipes used in nuclear power plants and reactors. A number of studies have investigated various locomotion mechanisms of robots controlled by electric cables in pipes. A cableless actuator capable of movement in narrow pipes of less than 15 mm has not yet been developed. The present paper proposes a novel cableless magnetic actuator with a propulsion module that exhibits a high thrusting force. The effect of the magnetic forces generated by two different propulsion modules on the movement of the cableless actuator was investigated theoretically and experimentally. The proposed actuator includes an electrical inverter that directly transforms DC from button batteries into AC. Experimental results indicate that the proposed actuator can move vertically at a speed of 225 mm/s, using the power provided by 10 button batteries when pulling no load mass. This cableless magnetic actuator has several possible applications, including inspection of small pipes. [ABSTRACT FROM AUTHOR]

This paper proposes a photovoltaic (PV)-battery hybrid system based on the cascaded H-bridge (CHB) inverter, which not only makes the irregular PV power smoother but also limits the grid current under grid voltage dips. Different from the conventional configuration where the PV and the battery inverters are paralleled on the grid side, the proposed CHB based hybrid system connects the AC sides of the PV inverter and the battery inverter in cascade. Thus, the multilevel inverter output voltage is available. Compared to the conventional configuration, the proposed system offers the improved electromagnetic compatibility (EMC) and better harmonic performance. The computer simulation has been given to verify the validity of the proposed system and control strategy. [ABSTRACT FROM PUBLISHER]

The pulse width modulation (PWM) inverter is widely used for the control of motors. We showed that the iron loss under PWM inverter excitation is affected by the impedance of the excitation circuit. The dc voltage of PWM inverter, which is widely used, is constant and the control of motor is carried out by changing the modulation index. Therefore, the evaluation of iron loss under PWM excitation with constant dc voltage is necessary in order to investigate the behavior of iron loss in an actual motor. In this paper, we measured iron losses of non-oriented electrical steel sheets under the shingle-phase full-bridge PWM inverter excitation and examined the influence of modulation index \mbi m, carrier frequency \mbi f\bf c and dc voltage \mbi V\bf dc on the iron losses. It is shown that the iron loss under PWM inverter excitation can be reduced when dc voltage \mbi V\bf dc is reduced and modulation index \mbi m is increased. [ABSTRACT FROM PUBLISHER]

The pulse width modulation (PWM) inverter has been used for the control of a motor since the rotating speed can be changed efficiently and easily. In order to estimate the iron loss in an iron core with sufficient accuracy under a PWM inverter excitation, it is necessary to understand correctly the influence of operating condition and circuit parameter on iron losses. In this paper, we measured magnetic properties of the nonoriented electrical steel sheet excited by a single-phase full-bridge PWM inverter using a ring specimen that corresponds to a magnetic circuit of an actual motor core. The effect of the carrier frequency and circuit resistance on the iron loss and the behavior of minor loops was examined. It is shown that the iron loss is increased when the circuit resistance is increased due to the generation of minor loops. Therefore, the circuit resistance should be decreased in an actual motor system. [ABSTRACT FROM PUBLISHER]

In this paper we present a new clocking method for non-reciprocal information transmission by an inverter chain of focused ion-beam engineered Co/Ni nanomagnets. The functionality of the clocking method is proven experimentally. Local focused ion-beam irradiation is used in order to define the direction of the information flow. The nanodots of the chain are clocked synchronously by a global external field. Information is transmitted synchronously between neighboring dots due to field-coupling. Magnetic force microscopy is used to reveal the magnetization state of the nanomagnets after every field pulse to prove the correct transmission of the signal. The switching characteristics of the fabricated nanodots and coupling forces between neighboring dots are analyzed optically using the magneto-optical Kerr effect. A detailed explanation is given for the occurrence of possible errors in a field coupled inverter chain. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel cableless magnetic actuator with a new propulsion module that exhibits a very high thrusting force and is capable of locomotion in a thin pipe by means of a new motion principle. The magnetic actuator is moved according to the vibration amplitude and elastic energy of a mass-spring system due to mechanical resonance energy. The proposed actuator contains an electrical inverter that directly transforms dc from button batteries into ac. The electrical dc–ac inverter incorporates a mass-spring system, a reed switch, and a curved permanent magnet that switches under electromagnetic force. Experimental results reveal that the actuator is able to move upward at a speed of 52 mm/s when powered by 10-button batteries and pulling a load mass of 10 g. [ABSTRACT FROM AUTHOR]

It is now evident that the value of endowing rotating machines with the capability to produce transverse forces in addition to their normal torque-producing function can be extremely high. The bridge configured winding is a cost-saving connection scheme for electrical machines to exploit transverse magnetic forces on the rotors. The winding scheme retains the machine's three-phase terminals such that ordinary motor inverters can be employed for the normal torque-producing function while providing separate terminals for transverse force action. This paper describes the practical implementation of such a winding connection in a conventional electric machine and demonstrates that controllable transverse forces can be produced. [ABSTRACT FROM AUTHOR]

To reduce the noise of a reactor under inverter power supply, the cause of noise should be investigated. For this purpose, we have already proposed a 3-D vibration analysis considering electromagnetism and magnetostriction, and the proposed method was applied to one phase of a reactor. It was found that the displacements in the yoke of the reactor are large and the hardness of insulators inserted in the gaps between cores affects the displacements. However, the optimal design to reduce the noise is not carried out. In this paper, first the better hardness of the gaps are determined by using the static structure analysis and a new design is proposed to reduce the noise. Moreover, the effectiveness of the improved hardness of gaps and the proposed new design of reactor is investigated by using the vibration analysis and the experiment. [ABSTRACT FROM AUTHOR]

This paper presents the use of coupled inductors to allow interleaved switching of the upper and lower switches of three-phase inverters. The approach increases the number of output voltage levels and reduces the magnitude of the output line currents at switching frequency. Two possible inductor topologies are investigated. Individual toriodal inductors for each phase are shown to provide more switching possibilities, at the cost of size and required DC fluxes. Three-phase three-limb inductors require more careful operation of the power electronics, but with significantly smaller core requirements. Simulated and measured inductor performance is presented, along with comments on the design of future inductors for similar applications. [ABSTRACT FROM AUTHOR]

Pulsewidth-modulated (PWM) inverters are used more and more to operate electrical machines and to interface renewable energy systems With the utility grid. However, there are abundant high-frequency harmonics in the output voltage of a PWM inverter, which increase the iron losses and result in derating of the machine or transformer connected to them. Predicting the iron losses caused by the PWM supply is critical for the design of electrical machines and transformers operated by PWM inverters. These losses are primarily attributed to eddy-current loss caused by the PWM Supply. In this paper, after analyzing the harmonic components of PWM voltage, we derive the effects of different parameters of PWM switching on the eddy-current loss. We compare the iron losses modeled with the proposed analytical methods on a three-phase transformer, a dc motor, and an induction motor with the results of time-stepping finite-element analysis and experiments. We provide detailed equations for the prediction of iron losses. These equations can be directly applied in the design and control of PWM converters and electric motors to improve energy efficiency in electrical machines and transformers operated from PWM converters. [ABSTRACT FROM AUTHOR]

This paper proposes optimal design method of stator slot for three-phase cage induction motor fed by six-step inverter output voltage by using proposed analysis method. The finite-element method (FEM) on one phase band stator periodic condition is coupled with harmonic equivalent circuit. Using the FEM, the stator slot is optimally designed and the result is presented. Stator core loss and copper loss including harmonic loss are reduced by the proposed optimum slot design method. The analysis result is verified by experimental measurement. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel method to calculate harmonic losses of permanent-magnet motors driven by pulsewidth modulation inverters. First, two-dimensional (2-D) nonlinear time-domain finite-element analysis is applied to estimate the harmonic rotational magnetic field at the air gap of the motor. Next, the three-dimensional frequency domain finite-element analyses at each remarkable harmonic field are carried out with the results of the harmonic gap flux densities obtained by the 2-D analysis. Using this procedure, the magnet eddy-current loss caused by the carrier harmonics of the inverter can be calculated with practical computer resources. [ABSTRACT FROM AUTHOR]

This paper deals with the characteristic analysis of a brushless dc motor (BLDC) taking into consideration the free-wheeling diodes and dc link voltage ripple using a time-stepped voltage source finite-element method. By comparing the experimental results, the authors show that the proposed computational method is useful for the analysis and design of a BLDC motor. They also examine the influence of freewheeling diodes and dc link voltage ripples on the performance of a BLDC motor such as torque ripples and radial force on the surface of the teeth. [ABSTRACT FROM AUTHOR]

In the paper the iron loss change, due to the modulation technique, in soft magnetic materials, supplied by single phase PWM (Pulse Width Modulated) inverters, is analyzed. Experimental tests on non oriented, oriented and amorphous materials are reported. The specific iron losses vs the flux density, for the two modulation techniques which are practically used in industrial converters, are presented for each analysed material. [ABSTRACT FROM PUBLISHER]