Vector Locus Research Articles

Evaluation of magnetic properties of two kinds of permendurs by vector magnetic measurement

Vector magnetic properties of various electrical steel sheets have been investigated by using a vector magnetic property measurement apparatus to select a magnetic material suitable as a motor core material. However, a magnetic material with a higher saturation magnetization than an electrical steel sheet is useful for increasing torque of a motor. Therefore, a permendur with higher saturation magnetization than an electrical steel sheet is selected as a measurement sample. It is known that a permendur does not have magnetic anisotropy. In this paper, vector magnetic properties of two kinds of permendurs made by VACUUMSCHMELZE (VAC) and Hitachi Metals are measured. Moreover, maximum magnetic field intensities and core losses of two kinds of permendurs to an inclination angle of magnetic flux density vector locus from rolling direction are evaluated for investigation of those magnetic anisotropies. As a result, differences of vector magnetic properties of two kinds of permendurs are revealed.

Adjustable Speed Drive Capability of Self-Excited Wound-Field Synchronous Motor Utilizing Space Harmonics With 500 W Class Prototype

In this paper, consideration from the viewpoint of the dq-axis current vector locus is reported on the clues for improving the output of wound-field motor utilizing space harmonic for field excitation. It is experimentally verified by visualizing the vector locus on the dq coordinates. First, voltage equation will be explained, and then the offline parameter estimation will be discussed. Then, visualization of the voltage-limit ellipse and vector locus will reveal clues for performance improvement.

Elliptic vector loci of average electron velocity of electron swarm in constant-collision-frequency model gas under ac electric and dc magnetic fields crossed at arbitrary angles

The analytic solution of the average electron velocity vector $$\mathbf {W}(t)$$ of an electron swarm in gas under ac electric and dc magnetic fields ( $$\mathbf {E}(t)$$ and $$\mathbf {B}$$ , respectively) in a constant-collision-frequency model is extended to cover not only the known case of a right crossing angle ( $$\mathbf {E}(t) \perp \mathbf {B}$$ ) but also the cases of arbitrary crossing angles ( $$\mathbf {E}(t) \not \perp \mathbf {B}$$ ). The x, y, and z components of $$\mathbf {W}(t)$$ are obtained as explicit formulae with the following parameters: the amplitude E of $$\mathbf {E}(t)$$ , the angle $$\theta $$ between $$\mathbf {E}(t)$$ and $$\mathbf {B}$$ , the angular frequency $$\omega _E$$ of $$\mathbf {E}(t)$$ , the cyclotron angular frequency $$\omega _B$$ (subject to the strength B of $$\mathbf {B}$$ ), and the electron collision frequency $$\nu $$ . A basic feature that $$\mathbf {W}(t)$$ draws elliptic locus in velocity space is unchanged even under $$\mathbf {E}(t) \not \perp \mathbf {B}$$ , but the plane including the locus may tilt when $$\omega _E$$ , $$\omega _B$$ , or $$\nu $$ varies. The derivation of $$\mathbf {W}(t)$$ based on the analytic solution of single electron motion is detailed and fundamental behavior of the $$\mathbf {W}(t)$$ loci is observed to understand the electron transport under $$\mathbf {E}(t) \times \mathbf {B}$$ fields.

Elliptic Vector Loci of Average Electron Velocity in Real Gases Under AC Electric and DC Magnetic Fields

Monte Carlo simulations (MCSs) of electron swarms in F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , Ar, and CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> under ac (radio frequency) electric and dc magnetic fields (E(t) and B fields) crossed at a right angle are performed, and the periodic response of the electron drift velocity vector W(t) is depicted as an elliptic vector locus (EVL). The vector head of W(t) draws an ellipse synchronously to the alternation of the ac E(t) field. The tilt of the major axis of the EVL, which represents the Hall deflection, increases with |B|, and the ellipse drawn by W(t) takes its maximum around the |B| value resonant to the ac E(t) field. It is demonstrated that a theoretical approximation derived from a constant-collisionfrequency (CCF) model predicts well the fundamental tendency of the |B|-dependent variation of the EVL of W(t) in the three real gases. The W(t) in F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> agrees well with the CCF model at low electric fields for its nature that the total collision frequency does not change significantly. On the other hand, those in Ar and CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> deviate from the CCF model. This visual depiction using the EVL of W(t) is expected to be applicable to the estimation of the directional electron drift in inductively coupled magnetized plasmas and to the characterization of the W(t) response in real gases.gases.

Practical Online Modulation Method for Current Ripple and Switching Losses Reduction in the Three-Phase Voltage Source Inverters

Convectional optimal pulsewidth modulation (PWM) current ripple reduction methods divide the vector space sectors into subsectors, where the reference vector is synthesized with a theoretically optimal sequence. However, extra CPLD/FPGA is needed for the lookup table and the PWM signal generation for alternative sequences. Moreover, when swapping in between sequences, extra switching and losses are introduced, which is particularly significant for low sample ratio operations. This article starts with an intuitive perspective on the sequence for current ripple reduction. Then, an online method is proposed to dynamically compute and select the sequence with the lower current ripples throughout the vector space. The proposed stationary frame current ripple vector locus peak computation and comparison methods can be efficiently implemented in DSPs. The proposed online method is equally effective in ripple reduction as the CPLD/FPGA based offline-optimized methods. Moreover, with low sample ratio commonly used in practice, the proposed method has even less switching losses, as it avoids extra switching during the sequences swapping. Elaborate lab setup makes it possible to obtain the switching losses of the previous methods over wide ranges of motor drive operation. Thereby, the switching losses advantages of the proposed method are validated.

On Methods of Checking Digital Out-Of-Step Protection Devices

The article addressed the issue of commissioning task that must take place before putting out-ofstep protection into operation. Most of the developers of digital out-of-step protection devices utilize control of impedance vector locus parameter during transient in a power system to detect its out-of-step operation, however checking the setting of such protection in the field conditions using existing means is often a challenging work. To facilitate the commissioning of such devices and provide means to automatize the process so as to rid of human factor the authors suggest means of simulating impedance vector locus with the desired parameters on the complex plane to check distance out-of-step protection. The means for checking current-oscillation based out-of-step protection is also considered. The results of a transient simulation representing instantaneous values of currents and voltages are saved in the international oscillography recording format COMTRADE, which makes it possible to carry out comprehensive verification of emergency control equipment using any kind of testing equipment that is able to generate the corresponding electrical signals stored in such format.

Development of Adaptive Feed-Forward Cancellation With Frequency Estimation Algorithm for Compensation of Periodic Disturbance at Arbitrary Frequency

Abstract In this study, an adaptive feed-forward cancellation (AFC) with frequency estimation algorithm has been developed to compensate for periodic disturbance at an arbitrary frequency. Conventional AFC was developed to compensate for periodic disturbance at a fixed frequency and cannot compensate for the disturbance in which the frequency varies in real-time. The proposed method can estimate the frequency of the disturbance in real-time by using the input and output signals of the AFC. It can compensate for the periodic disturbance at an arbitrary frequency. In addition, the stability of the feedback control system with the proposed AFC can be optimized at any frequency based on the vector locus of the open-loop characteristic on the Nyquist diagram. The effectiveness of the proposed AFC was confirmed in experiments compensating for whirling vibration, whose frequency varies in real-time in rotating machinery. The proposed AFC can estimate the frequency of the disturbance automatically and compensate for this adequately.

Time‐domain computation of rotational iron losses considering the bulk conductivity for PMSMs

This study investigates an advanced finite-element (FE) technique for the evaluation of rotational iron losses based on a time-domain computation, where the bulk conductivity of the core materials is considered. The iron-loss characteristics are discussed for a radial flux permanent magnet synchronous machine (PMSM) for a wind generation application, with closed slots and outer rotor topology. The following factors are taken into account: (i) a real-time rotational iron-loss computation; (ii) the bulk conductivity of the steel laminations; and (iii) the influence of the controller harmonics on the system during transient conditions. The magnetic induction vector locus of each iron component is also discussed, where the magnetic induction is numerically modelled [three-dimensional (3D) finite element analysis (FEA)], computed using multiple magnetic antennae and is also experimentally verified. This comparative study shows a torque–frequency-loss computation that is presented from low to high frequencies (50–800) Hz. The FE model of the total iron losses for the PMSM using both pure sinusoidal and proportional–integral pulse-width modulation currents is studied and experimentally verified on a surface-mounted PMSM. The proposed method of iron losses prediction significantly reduced the rate of error between 3D FEA and experimental data to 1.7%.

Development of optimal controller design method to compensate for vibrations caused by unbalanced force in rotor system based on Nyquist diagram

In this paper, an optimal controller design method is proposed to compensate for vibrations caused by unbalanced force in the rotor system. The vibrations caused by unbalanced force are the major root cause of excessive whirling vibration in the rotor system, and it is important to compensate for the vibration to maintain its stable operation. The proposed design method can optimize a performance of the controller based on the vector locus of open loop characteristics on the Nyquist diagram. To verifiy the effectiveness, the proposed design method was employed for three typical active vibration control methods. The experimental results show that the proposed method can design the optimal parameters to compensate for the whirling vibrations of the rotor system.

RESEARCH ON DIRECT TORQUE CONTROL OF BRUSHLESS DC MOTOR BASED ON NEW STATOR FLUX LINKAGE SETTING

Aiming at the torque ripple problem of Brushless DC motor, a new stator flux setting method is proposed on the basis of direct torque control system. Firstly, the basic forming principle of traditional stator flux vector locus of circular and hexagonal is analyzed.And then, a new stator flux linkage setting method based on rotor position and dynamic current mode is proposed.The new stator flux linkage method is applied to the direct torque control system of Brushless DC motor.Theoretical analysis shows that the given flux linkage trajectory is consistent with the expected reference value, the torque ripple is smaller. The simulation results verify its effectiveness and are suitable for BLDCM DTC operation.

48V 계자 권선형 동기전동기 고성능 자속기반 토크제어

In this paper, High performance torque control based on the flux mapping of 48V Wound Rotor Synchronous Motor has been studied to improve torque control. Flux map considering MTPA (Maximum Torque Per Ampere), MFPT (Minimum Flux Per Torque), Maximum efficiency point at the same torque command and flux command for each field current was produced. Current map using flux mapping of Each field current was applied to the MTPA, MFPT. Generating a current vector locus was to determine the characteristics of the operation region. Through the Matlab/Simulink simulation, difference between speed-torque map and flux map was represented. The suggested flux map was tested actual experiments on a dynamometer.

Modulation and control of ac/dc matrix converter for battery energy storage application

In this study, ac/dc matrix converter is applied in battery energy storage system (BESS). Aiming at reducing the dc current ripple and regulating the active and reactive power, modulation and control strategies are investigated in depth. First, a novel dc current ripple analysis approach using a geometric description of ripple vector locus is proposed. Then a simple optimal switching pattern with minimum dc current ripple under arbitrary power factor condition is developed and is compared with conventional switching patterns. On the basis of the characteristics of ac/dc matrix converter, a control scheme suitable for BESS is presented. The strategy can realise independent grid side active power control (battery charging/discharging control) and reactive power control. The simulation and experimental results verify the effectiveness of the proposed switching pattern and control strategy, and demonstrate the feasibility of applying ac/dc matrix converter in BESS.

Modeling and Analysis of Stator Interturn Fault Location Effects on Induction Machines

Locating the stator interturn (SIT) fault on the motor winding structure adds an important feature in the fault diagnosis. This motivates to study the effects of SIT fault location on the induction machine. In this paper, a simple yet accurate stationary reference frame q-d-0 model of SIT-faulted induction machine, including the fault location parameter, is developed. The fundamental components of winding functions (WFs) are used to calculate the machine inductances for the proposed model. These inductances in stationary reference frame q-d-0 variables are rotor-position-independent expressions and functions of fault severity and fault location. The proposed model is as accurate as the multiple-coupled-circuit model for fault location study. It does not require the recalculation of machine inductances in each integration step to solve the model. The experimental validation of the model is presented. The steady-state analysis based on the proposed model indicates that the inclination of the current vector locus and the phase angle of the negative-sequence current phasor are the strong indicators of the SIT fault location.

A study of equivalence between adaptive learning and loop shaping methods for disturbance compensation

AbstractThis paper introduces a theoretical analysis of the disturbance compensation methods in positioning systems. Thereare two major methods used to compensate for disturbances. The first one is based on a loop shaping method andthe second one is based on an adaptive learning method. We make a comparison between a resonant filter used asthe loop shaping method and an enhanced adaptive feed-forward cancellation (AFC) method used as the adaptivelearning method. To compensate disturbances, the resonant filter decreases the gain of the sensitivity function atthe disturbance frequency by using the vector locus. The adaptive learning method adjusts the coefficients of theenhanced AFC to compensate for a disturbance. We found that the LTI model of an enhanced AFC is the sameas that for a resonant filter when we compared their characteristics. A simulation of the disturbance compensationin a hard disk drive showed that these time responses and frequency responses coincided. Moreover, the resultsshowed advantages of each of the control methods with the exception of the performance. A resonant filter realizeslow cost implementation with compare to an enhanced AFC. That is, a resonant filter easier to implement than anenhanced AFC. An enhanced AFC has the utility to realize a high quality function control system simultaneouslyable to compensate and estimate for disturbances. The results of the evaluation in this study will provide designengineers with guidelines for selecting an optimum control strategy in actual applications.Key words : Disturbance compensation, Periodic disturbance, Non-periodic disturbance, Adaptive feed-forward

Unconventional P-35S sequence identified in genetically modified maize

The Cauliflower Mosaic Virus 35S promoter sequence, CaMV P-35S, is one of several commonly used genetic targets to detect genetically modified maize and is found in most GMOs. In this research we report the finding of an alternative P-35S sequence and its incidence in GM maize marketed in Jordan. The primer pair normally used to amplify a 123 bp DNA fragment of the CaMV P-35S promoter in GMOs also amplified a previously undetected alternative sequence of CaMV P-35S in GM maize samples which we term V3. The amplified V3 sequence comprises 386 base pairs and was not found in the standard wild-type maize, MON810 and MON 863 GM maize. The identified GM maize samples carrying the V3 sequence were found free of CaMV when compared with CaMV infected brown mustard sample. The data of sequence alignment analysis of the V3 genetic element showed 90% similarity with the matching P-35S sequence of the cauliflower mosaic virus isolate CabbB-JI and 99% similarity with matching P-35S sequences found in several binary plant vectors, of which the binary vector locus JQ693018 is one example. The current study showed an increase of 44% in the incidence of the identified 386 bp sequence in GM maize sold in Jordan’s markets during the period 2009 and 2012.

Analysis of Distribution, Pattern, and Vector of Electric Field in the Inter Phases Region of Three-phase Gas Insulated Switchgear

This paper deals with the electric field characteristics in the inter-phases region of three-phase gas insulated switchgear (GIS). The electric field in a three-phase construction of a simplified GIS model was analyzed. The results show that in the inter- phases region the direction and the magnitude of electric field vector varies with the location of the observation point while in the phase-enclosure region the direction of the electric field vector tends to linear and constant. There is no zero electric field on the particle tip of a particle in the inter-phases region, except S90 particle. There is zero electric field on the particle tip of a particle in the phase-enclosure region every half cycle of applied voltage. The maximum electric field of the particles on the inter-phases region generally is higher than one of the particles on the phase-enclosure region. The electric field vector locus in the inter-phases region varies: linear, elliptic, or circular while one in phase-enclosure region is constant and linear.

Electric Field Characteristics Inside Three-phase Gas Insulated Switchgear in the Presence of Foreign Metallic Particle

Abstract Three-phase equipment differs from single-phase equipment in two aspects: configuration and applied voltage. In this paper the effects of these differences on electric field in the presence of foreign metallic particle in three-phase GIS are reported. The electric field characteristic in three-phase GIS is different from that in single-phase one. There are periodic changes in the electric field magnitude and direction produced by three-phase voltage at any point. While the voltage phase varies, the electric field vector changes and rotates continuously. The rotating characteristics of the electric field vector in three-phase power apparatus depended on the position inside the insulation of the tank. The electric field vector locus is circular, elliptic, or linear. The elliptical nature of rotating electric field is expressed as electric field ratio. The presence of foreign metallic particle increases significantly the maximum electric field on the particle tip, but its effect on minimum electric field is not significant. The electric field ratio in the presence of particle is lower than one without particle.

HEART DEPOLARIZATION VECTOR LOCUS CARDIOGRAM AND ITS CLINICAL DIAGNOSTIC APPLICATIONS

This study demonstrates the development of the heart depolarization vector locus cardiogram (HPVLC, from limb leads and a modified Einthoven's triangle) as a diagnostic measure of the left ventricular depolarization strength. Our work involves the reconstruction of the "equivalent heart electrical-activity vector (HAV)" for the QRS complex from limb leads voltages of a sample ECG recording, and plotting the progression of the cardiac vector during the QRS complex. A realistic visualization of the progression of the equivalent-dipole HAV during the QRS complex is possible by staging the HPVLC of the QRS complex from the onset of the QRS till the end of the depolarization stage. This can enable the characterization of the HPVLC by means of an analytical function. By studying the HPVLC for various electro-cardiological disorders, it is possible to determine the ranges of the analytical function's parameters for normal and disordered electro-cardiological states, for diagnostic purpose. We have seen that the monitored ECG is theoretically derived from HAV components on the sides of the Einthoven triangle. Nevertheless, in cardiac practice, the monitored ECG is employed in diagnosis of heart diseases. From the ECG, we can obtain the heart rate, and therefrom the heart rate variability, which too has diagnostic applications. Many nonlinear methods have been proposed to analyze ECG and HRV for detection of cardiac abnormalities, using linear and nonlinear methods. Herein, we have shown how HRV signal can be analyzed in terms of four recurrence quantification analysis (RQA) features, which are then combined into an Integrated Index to enable better separation of normal and diabetic subjects.

Electric Field Characteristics under Three-phase Voltage in Three-phase Gas Insulated Switchgear

This paper deals with electric field characteristics under three-phase voltage in three- phase gas insulated switchgear (GIS). Three-phase equipment differs from single-phase equipment in two aspects: configuration and applied voltage. In this paper the effects of these differences on electric field in three-phase GIS are reported. There are periodic changes in the electric field magnitude and direction produced by three-phase voltage at any point. While the voltage phase varies, the electric field vector changes and rotates continuously. The rotating characteristics of the electric field vector in three-phase power apparatus depended on the position inside the insulation of the tank. The electric field vector locus is circular, elliptic, or linear. The elliptical nature of rotating electric field is expressed as electric field ratio. The mathematic description of the rotating electric field is given considering the maximum and the minimum electric field and the position inside the insulation. There is no zero electric field under three- phase voltage. The areal velocity of the electric field vector locus is constant. The electric field vector moves slowly in a high electric field area, but moves quickly in a low electric field area.

Optimization of adaptive feedforward repeatable run-out cancellation for positioning control system of hard disk drives

To increase the recording density of hard disk drives, suppression of the disturbances is essential. In this paper, we focus on the suppression of repeatable run-out. This paper presents the design method of an adaptive feedforward cancellation (AFC) which can suppress a periodic disturbance. AFC is adaptive filter. The algorithm can be converted into a linear time-invariant (LTI) model. The LTI model is considered to be a peak filter for a closed loop system. Therefore, parameters of AFC should be designed in consideration of a closed loop characteristics. The proposed method can design the parameters that can achieve a vector locus to recede from the critical point [− 1, 0] on the Nyquist diagram. As a result, convergence performances and stability performances of AFC are optimized in frequency domain. The effectiveness of the proposed method is verified by the simulations and experiment of the hard disk drive.