Influence Of Windings Research Articles

Influence of Concentric and Unequal-Turn Windings on Vibration of Induction Machines Considering Supply With Low-Order Harmonics

Influence of Concentric and Unequal-Turn Windings on Vibration of Induction Machines Considering Supply With Low-Order Harmonics

CALCULATION OF POWER TRANSFORMER INDUCTANCE MATRIX

Practical calculations of electric equipment and electric networks are performed using equivalent circuits. Without taking into account saturation phenomena, electromagnetic processes in a power transformer are described by a system of linear equations, which can be represented in matrix form. The transformer inductance matrix contains self and mutual winding inductances, whose values for one phase are determined directly from the passport data containing the results of no-load and short circuit experiments. Mutual inductances between phases depending on the type and size of the magnetic core are not usually given in the transformer documentation. It does not allow to simulate the operating modes that differ from the steady state with uniform phase load.
 
 The purpose of the work is to develop an algorithm for calculating elements of the power transformer inductance matrix according to its passport data and magnetic circuit parameters.
 
 The scientific novelty lies in use of information about magnetic circuit type and size to determine elements of the inductance matrix.
 
 Materials and methods. Methods of linear electric and magnetic circuit theory are used in the work.
 
 Results. The proposed algorithm for calculation of power transformer inductance matrix includes three stages: calculation of self and mutual inductances for one phase; construction of an equivalent circuit for a magnetic circuit and calculation of magnetic fluxes in order to take into account the mutual influence of windings on various phases; assembly of the inductance matrix of three-phase transformer. A method is proposed for constructing the transformer inductance matrix with an arbitrary type of magnetic circuit, phases and windings quantity. The method involves preliminary calculation of the coefficient matrix that characterizes the magnetic circuit and depends mainly on its type and, to a less, on the ratio of geometric dimensions in rods and yokes. The coefficient matrix can be calculated in advance and used to determine the inductance matrix of a wide range of transformers.
 
 Conclusions. 1. The passport data of the transformer do not allow to model transformer operation at unbalanced load validly. 2. An algorithm for determining the inductance matrix of transformers has been developed. 3. A method for compilation of a transformer inductance matrix with an arbitrary type of magnetic circuit, the number of phases and windings is introduced. The practical significance of the algorithm is determined by the simplicity of algorithmizing, as well as by the possibility of using it in computer simulation of electrical circuits with transformers, for example, using the modified nodal analysis method.

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

To improve the study on the influence of transformer windings and pad support on transformer short-circuit resistance, the calculation method of wire bending elastic modulus is analyzed, and the sample test is carried out: The influences of the unbalance of the two ends of the wire between the number of wires wound and the span of adjacent pads on the force-deflection curve, the bending force at the selected deflection, and the elastic modulus of bending were analyzed. The results showed that: Increasing the number of wires and decreasing the height difference of adjacent pads can improve the bending force and bending elastic modulus of wires, the axial stability, and short-circuit resistance of transformer windings. When the height of the adjacent pad is not balanced, the axial force can increase the compression degree between the pad and the wire, and reduce the span of the wire. Under the action of force, the wire yields twice, which further reduces the bending force and elastic modulus of the wire. This research can provide test data support for improving the installation of transformer winding pads and theoretical evaluation of short-circuit tolerance.

Optimization of Stator Slot Parameters for Electromagnetic Vibration Reduction of Permanent Magnet Synchronous Motors

Slight electromagnetic vibration is one of the crucial indicators that must be considered in the motor design stage. Considering the influence of complex stator slot structure and inevitable saturation at slot opening, a permeance calculation model suitable for the motor with any pole-slot combination is introduced, and the electromagnetic force waves of the motor are calculated quickly and accurately. Considering the orthogonality of stator material and the influence of enclosure and windings, the natural frequencies of the entire stator are analyzed, and the vibration accelerations are calculated by the multiphysics model including control, electromagnetic, structural, and vibration models, the accuracy of the calculation results is verified by the prototype test. Furthermore, the components of electromagnetic force waves that have great impact on electromagnetic vibration are summarized, a weakening method of electromagnetic vibration based on the optimization of the stator slot parameters is proposed, and the optimal stator slot parameters are obtained by the simplified model and the accurate model combining deep neural network (DNN) and immune clone algorithm (ICA), respectively. For the 6-pole 36-slot motor, the vibration accelerations near the six-order natural frequency are greatly reduced by optimizing the stator slot parameters based on the accurate model combining DNN and ICA, and the maximum vibration accelerations are reduced by 34.1% at no load and 36.8% at rated load.

Study of Two-Phase Induction Motor with Non-Orthogonal Stator Windings in Sensorless Systems

Abstract In this paper, the operation of a two-phase induction motor (TPIM) with non-orthogonal stator windings is studied, in a stationary reference frame. Through modeling and simulation on the Matlab/Simulink environment, the influence of the electrical shift angle stator windings on the magnetic and electromechanical quantities of the machine, in transient mode, will be highlighted. Also, another problem studied refers to the determination of the rotor flux of the TPIM by the estimation method, thus avoiding the use of the flux sensor. It was decided to use estimators derived directly from the machine equations written in motor mode, estimators used in electrical drives with analog control. And in this case, simulation was used to highlight, in a transient regime, the performance of using these flux estimators.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ЕЛЕКТРИЧНОЇ МАШИНИ З ТРИСТУПЕНЕВИМ ГІРОСТАБІЛІЗОВАНИМ РОТОРОМ

A retrospective review of the development of the theory and practical structures of electric machines with a three-degree-of-freedom rotor (EMTR) at the Institute of Electrodynamics of the National Academy of Sciences of Ukraine. The applications of EMTR in surveillance, tracking and stabilization systems on moving objects are listed. The relevance of the development of such machines is shown. The disadvantages of the classical mathematical model of EMTR are noted and the need to develop a refined mathematical model due to the need to develop new technology, the emergence of new materials and electronic components, as well as the growth of computing capabilities. The two main known structures of EMTR are described and the advantages of the perspective structure chosen as the basic one are listed. The model of static three-dimensional magnetic field of EMTP and the associated dynamic model in the COMSOL Multiphisics environment are substantiated and constructed for the basic structure of EMTR. The connection between the magnetostatic problem and the rotor motion dynamics problem is ensured by the fact that the data of the calculated instantaneous characteristics are transmitted in the form of approximated dependences to the dynamic problem. In the mode of free rotation without losses, the dependences of the precession angle on time, amplitude and phase of the sinusoidal current of the control winding are calculated. High accuracy of observance of the direction of precession of the axis of the rotor at observance of the corresponding initial phase of sinusoidal current of a control winding is noted. The influence of rotation windings on the moment created by the control winding is investigated. References 3, figures 8.

Investigation of Open-Circuit Fault-Tolerant Strategy in a Modular Permanent Magnet Synchronous In-Wheel Motor Based on Electromagnetic–Thermal Analysis

This article investigates the asymmetric temperature distribution of a modular permanent magnet (PM) synchronous in-wheel motor under fault conditions, and based on this, proposes a fault-tolerant (FT) strategy named minimum temperature difference strategy (MTDS) to avoid the high temperature appearing at local winding. First, the modular motor system and the FT principle are introduced, and the reconfiguring fundamental magneto motive force (MMF) under open-circuit of one phase in one module is deduced. Second, the loss and temperature distributions of the motor with normal operation are analyzed by the coupled electromagnetic–thermal method. And the mutual verification between simulation and experiment is adopted to separate the copper losses, iron losses, and PM losses from total losses. Furthermore, the asymmetric temperature distributions of the motor operating with part of modules are analyzed in detail. Finally, the influence of the faulty windings on the temperature of healthy windings is investigated, and the FT strategy of MTDS is proposed. The asymmetric temperature distributions of the motor under various FT strategies are compared. The result shows that the MTDS can significantly reduce the maximum temperature of the windings and makes the winding temperature distribution more uniform.

Автоматизация проектирования трехфазного двухскоростного асинхронного двигателя

The subject of research is double-speed asynchronous motors of the type produced by SPA ELSIB PJSC with two independent windings in the stator designed to drive the main circulating pumps of nuclear power plants as well as similar mechanisms in other sectors of the national economy. The article deals with specific issues of the full cycle of calculating the considered electric ma-chine. We propose a method of research on mutual influence of stator windings when the motor works based on the fundamental positions of the theory of electrical machines using numerical modeling. Also, a method of choosing an air cooler to be used in thermal calculation taking into account the features of the machine type under investigation is proposed. The research purpose is to optimize the full cycle of calculating a new motor of this type under development. This is due to the occurrence of additional heating in one stator winding due to the operation of the other, which increases labor costs caused by the need to take into account an additional heat source during thermal calculation. In addi-tion, the existing empirical dependencies do not fully reflect the entire physical picture of the ongoing processes. The originality of the research lies in the fact that based on the known provisions the algo-rithm for calculating the applied air cooler has been modified due to automation, which contributes to correct protection against thermal overheating effects. It is shown that by numerical modeling it is possible to minimize labor costs for determining the parameters taken into account in the subsequent thermal calculation that arise as a result of the mutual influence of the selected machine type stator windings. The research results are tried out in SPA ELSIB PJSC manufacture and presented by the motor specific example.

Modeling of electromagnetically excited noise and vibration of induction motor

For electric vehicles, acoustic noise of traction motor excited by electromagnetic force is one of the main sources of noise, especially when automobiles are driven at low speed where noise from other sources are comparatively low. To analyze the characteristics of the noise and propose noise reduction suggestions, an accurate noise prediction model is needed. In this paper, a multi-physics model to predict the electromagnetic force excited acoustic noise of induction motor is presented. First, a three-dimensional (3-D) transient electromagnetic model of the motor was established using finite-element method (FEM). The uneven distributed time-varying magnetic force was calculated, and the current harmonics due to pulse width modulation (PWM) supply were considered. Then, a structural model was built, in which the anisotropy characteristic of silicon sheets stacked stator core, as well as the influence of windings, were considered through the assignment of orthotropic parameters to the stator core. Through mesh mapping, the FEM calculated magnetic force was transferred onto the structural model and the forced vibration was calculated using mode superposition method. Base on that, the acoustic noise was further obtained using boundary-element method (BEM). Finally, the noise and vibration of the studied induction motor were tested in a semi-anechoic room. As the simulated results show a good accordance to the measured data, the accuracy of the model was verified.

A Control System of an Electric Drive with a Synchronous Reluctance Machine with Independent Excitation

A method for adjusting frequency-regulated drives with the synchronous reluctance machine with independent excitation is proposed using the KhPT-250 cold tube reducing mill and traction drive of a Gazelle-Next electric vehicle as example; the method consists in independent adjustment of the phase currents with the subsequent identification of parameters of the control object by methods of frequency identification. It has been shown that, with independent control of the excitation currents and the anchor reaction, the cross links between phase current control loops can be neglected, which can be accounted for by the large bandwidth of the uniform pass-through frequency of the phase current control loops and the weak influence of phase windings located in the interpolar gap on the operation of the phase windings that currently located above the pole. It has been shown that when the drive operates at high speeds, a significant decrease in the proportionality coefficient between the magnitude of the electromagnetic moment and current is observed, which is explained by the finite speed of the phase current control loop. When adjusting the electric drive control system with dual-zone speed control, it has been suggested to introduce a correction for the anticipatory effect of the phase current in order to provide a constant relationship between the anchor component of phase current and the magnitude of electromagnetic moment.

Интерпретация частотных характеристик силовых трансформаторов с применением матрицы проводимостей обмоток

Frequency response analysis (FRA) is widely used to assess the mechanical and electrical conditions of the power transformer and shunt reactor windings. The requirements for the FRA and for frequency response measurement equipment have been standardized in the IEC 60076-18 standard. However, there still remain many questions concerned with interpreting the frequency response measurement results. As is well known, electrical faults and serious mechanical damages of certain transformer windings entail significant changes in the winding frequency responses. In the general case, the measured transformer winding is coupled with the other windings, a circumstance that has an effect on the frequency responses obtained for an individual winding and adds difficulty to assessing the condition of the transformer windings. It is shown—based on representing the transformer as a multiterminal circuit with the matrix of winding admittances—that the frequency responses measured according to the standard schemes are coupled with it. It is shown, taking as an example the transformer with a delta-connected winding, that the mutual influence of windings can lead in practice to an incorrectly assessed condition of individual winding phases. Matters concerned with the use of non-standard measurement schemes, including those for measuring the winding admittance matrix entries, are considered with the aim to obtain additional diagnostic information and interpreting the frequency response measurement results.

Modeling and Simulation of Excitation System for Third Harmonic Brushless Synchronous Generator

The excitation system of third harmonic excitation brushless synchronous generator (HESG) can improve the voltage stability and is widely used in small and medium generator set. In order to establish the model of harmonic brushless excitation system, the formula of third harmonic EMF is derived. Then, based on the traditional synchronous generator model, the influence of harmonic windings is counted in. Finally, the simulation model of closed-loop excitation system is analyzed with the automatic voltage regulator (AVR) as the core. On the basis of theoretical analysis, simulation and comparative analysis are carried out according to parameters from actual system. The results show that compared with normal synchronous generator, HESG has the advantage of excellent dynamic characteristics and automatic voltage adjustment.

Effects of damper winding, eddy current, and leakage flux on magnetic field distortion and stator electrical quantity research of nuclear power turbo‐generator under external asymmetry

One phase overload or lightload condition is a very common condition in nuclear power turbo‐generators, and magnetic field distortion and current asymmetrical degree concern the safe operation of turbo‐generators. Damper and wedge windings are the special parts that distinguish the nuclear power generators from other smaller generators. Therefore, it is extremely important to investigate magnetic field distortion and stator electrical quantity. At the beginning, taking saturation and slot effects into account, the finite element model of a 1400MVA nuclear power generator is built up. And through comparison between the finite element simulation and the experimental results of no‐load characteristics and short‐circuit characteristics, the effectiveness of the finite element model was fully tested. Then, with or without damper and wedge windings, and leakage flux, the negative sequence equivalent circuit is employed to explain the law of magnetic field distortion under stator negative current, which is also verified by finite element simulation. Based on a novel theory proposed in this article, the law of the stator positive and negative sequence current, and the current asymmetrical degree with alteration of one‐phase load under steady state are given in detail. Additionally, the finite element method is developed to test the correctness of the novel theory. The influence of damper and wedge windings, leakage flux at coil ends, and eddy current on the solid magnetic‐pole of rotors on stator electrical quantity is also discussed in detail. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Fault Detection and Tolerant Capability of Parallel-Connected Permanent Magnet Machines Under Stator Turn Fault

This paper analyzes the influence of stator windings turn-to-turn fault on inverter-fed permanent magnet (PM) machines. By adding a secondary neutral point (NP) in stator windings, the turn fault detection and tolerant capability can all improve considering a small turn-to-turn short at an early stage. From the perspective on fault detection, the proposed windings with two NPs increase the equipment impedance per NP. Once a turn fault occurs, the fault-induced voltage harmonic magnitude increases. It results in a better signal-to-noise ratio for the fault detection. From the perspective on tolerant drive, the fault-induced circulating currents can flow across different phase coils in the windings with two NPs. Reduced effect on circulating currents in a faulty machine is achieved due to the current diversion. Turn fault induced additional losses are then decreased compared to conventional windings with only one NP. A 1-kW PM machine with two different windings is tested to verify the fault detection and tolerant performance.

The realization of the virtual synchronous generator based on the park model

In this paper, a kind of virtual synchronous generator control algorithm is proposed that can accurately simulate the external characteristic of a synchronous generator. This algorithm based on the synchronous generator park mathematical model considers the motor salient pole effect and the influence of damper windings. Using two-step Adams method to solve the mathematical model of the synchronous motor for current of the motor’s port, the converter is controlled to track the current so that the output status values have the same port characteristics with the actual motor. Simulation results verify that in many typical working conditions such as the synchronous motor starting, the output voltage mutating or the frequency changing, the converter controlled in the above algorithm can mimic a real synchronous generator.

Analytical Calculation and Analysis of Main Generator Inductance of Aero Brushless Three-stage Synchronous Starter/Generator System

Precise electro-magnetic parameters are significant in the investigation of characteristic for brushless synchronous starter/generator system, especially the inductance during the starting process.This paper presented an analytical method for inductance calculation, which analysed the influence of stator windings’ parallel structure on inductance calculation and took the skewed slot structure into consideration. Due to the skewed slot structure, applicable two-dimensional coordinate systems were established .This proposed method could save time in calculation according to the simplification to some extent. The results of analytical method were presented and compared with the simulation results. The reason for the differences has been analyzed.

Improvement of Three‐Phase Unbalance Due to Connection of Dispersed Generator by Damper Windings of Synchronous Generator

SUMMARYIt is well known in the numerical simulations of a synchronous generator that the damper winding contributes to suppressing three‐phase circuit unbalance in power systems. However, an experimental study has not been performed yet. In this paper, we verify experimentally the suppression of three‐phase unbalance by the damper windings. In order to simulate the three‐phase unbalance, a 470‐W dispersed generator of single‐phase two‐line type was connected to a three‐phase laboratory‐scale power system that included a 6‐kVA synchronous generator. We measured and analyzed line voltages and currents as well as damper bar currents both with and without the dispersed generator. The influence of damper windings on the unbalance of the three‐phase circuit was also investigated. The results show that the damper winding contributes to improving the three‐phase unbalance. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 43–50, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22305

Design of Brushless Electric Excitation Synchronous Machine

Brushless electric excitation synchronous machine is a new kind of AC machine. There are two sets of windings with different pole numbers on the stator. It eliminates the brushes and slip rings. The air gap magnetic density of brushless electric excitation synchronous machine is achieved based on Ansoft. And the influence of stator windings with different pole numbers on coupling capability is analyzed. All the results are investigated to provide the guide for the optimal design.

Improvement of Three-phase Unbalance due to Connection of Dispersed Generator by Damper Windings of Synchronous Generator

SUMMARY It is well known in the numerical simulations of a synchronous generator that the damper winding contributes to suppressing three-phase circuit unbalance in power systems. However, an experimental study has not been performed yet. In this paper, we verify experimentally the suppression of three-phase unbalance by the damper windings. In order to simulate the three-phase unbalance, a 470-W dispersed generator of single-phase two-line type was connected to a three-phase laboratory-scale power system that included a 6-kVA synchronous generator. We measured and analyzed line voltages and currents as well as damper bar currents both with and without the dispersed generator. The influence of damper windings on the unbalance of the three-phase circuit was also investigated. The results show that the damper winding contributes to improving the three-phase unbalance. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 43–50, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22305

The influence of power stator windings of the asynchronous traction motors for dynamic workload elements of traction drive locomotive

The results of studies on determination of loading level of tractive drive elements in some operating conditions, when the values of frequencies of the change of feeding currents of stator windings are to be obtained in both subcritical and ultracritical zones for two types of the tractive gear are presented in the paper.