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Purpose In this paper, a new structure for the permanent magnet hysteresis synchronous (PMHS) motor is introduced. Moreover, this paper aims to presents a new analytical method for modeling of a disc-type PMHS motor.Design/methodology/approach Because the hysteresis and permanent magnet motors have unique characteristics, a motor (the PMHS motor) with excellent performance features can be achieved by combining them. Choosing a disc-type slotless structure causes the major advantages of both motors to be preserved in the new motor. To analyze PMHS motor, mathematical equations are obtained by using Ampere’s circuital law, flux continuity law and Faraday’s law. Then the air-gap voltage and exciting current of the motor can be calculated. To implement this method, a new iterative algorithm is proposed. This algorithm consists of one-iteration loop for each input voltage to find the maximum flux density of the operational hysteresis loop of the motor.Findings Validity of the analytical approach is confirmed by experimental results. A reasonably close agreement between the two is shown and some outstanding performances of the PMHS motor are demonstrated.Originality/value A new structure for PMHS motor and also a new analytical method for performance prediction of this motor is presented. [ABSTRACT FROM AUTHOR]

Purpose – The novel bearingless switched reluctance motor (BSRM) is proposed recently, which is different from the conventional BSRM in the stator structure and suspension winding arrangement. The reduced number of suspension windings makes the novel BSRM much simpler, so that the control circuit and algorithm are greatly simplified when compared to those of the conventional BSRM. This paper for the first time proposes the novel BSRM's analytic model, including the mathematical relationships among the winding currents, rotor angle, radial forces, and motor torque, to further achieve the suspending forces and torque control. The paper aims to discuss these issues. Design/methodology/approach – The magnetic equivalent circuit method is employed to obtain the self-inductances and mutual-inductances of the motor torque windings (main windings) and suspension windings (control windings). The straight flux paths are combined with the elliptical fringing flux paths to calculate the air-gap permeances, and the stored magnetic energy. Then, the mathematical expressions of radial forces and torque are derived. A novel BSRM prototype is analyzed through using the proposed analytical model and the finite element model. The results of both methods are compared to verify the proposed mathematical model. Findings – The proposed mathematical model of the novel BSRM considering unsaturated magnetic circuits is verified by finite-element analysis results. Research limitations/implications – The mathematical model represents the situation of magnetic circuit unsaturated and is not suitable for the magnetic circuit saturation. It cannot be used to control the motor which is working in the deep magnetic circuit saturation region. Practical implications – Building mathematical model is a necessary step for the motor's suspension and rotating control. The built model provides the fundamental for the preliminary control algorithm and experimental study of this novel BSRM. Originality/value – For the first time, the novel BSRM's mathematical model is proposed. It provides necessary fundamental for the motor's further analysis, design, and suspending and rotating controls. [ABSTRACT FROM AUTHOR]

Purpose - The aim of this paper is to access performance of existing computational techniques to model strongly non-linear field diffusion problems. Design/methodology/approach - Multidimensional application of a finite volume front-fixing method to various front-type problems with moving boundaries and non-linear material properties is discussed. Advantages and implementation problems of the technique are highlighted by comparing the front-fixing method with computations using fixed grids. Particular attention is focused on conservation properties of the algorithm and accurate solutions close to the moving boundaries. The algorithm is tested using analytical solutions of diffusion problems with cylindrical symmetry with both spatial and temporal accuracy analysed. Findings - Several advantages are identified in using a front-fixing method for modelling of impulse phenomena in high-temperature superconductors (HTS), namely high accuracy can be obtained with a small number of grid points, and standard numerical methods for convection problems with diffusion can be utilised. Approximately, first order of spatial accuracy is found for all methods (stationary or mobile grids) for 2D problems with impulse events. Nevertheless, errors resulting from a front-fixing technique are much smaller in comparison with fixed grids. Fractional steps method is proved to be an effective algorithm for solving the equations obtained. A symmetrisation procedure has to be introduced to eliminate a directional bias for a standard asymmetric split in diffusion processes. Originality/value - This paper for the first time compares in detail advantages and implementation complications of a front-fixing method when applied to the front-type field diffusion problems common to HTS. Particular attention is paid to accurate solutions in the region close to the moving front where rapid changes in material properties are responsible for large computational errors. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to introduce a method based on the fuzzy correlation for modelling of active and reactive powers from the substations of the electrical distribution systems, at the peak load. Design/methodology/approach – Based on the correlation theory, the fuzzy models of the loads can be obtained using a new algorithm. If in the case of the principal/connection station there is sufficient database information for a good forecasting of the load, then for those substations where data are missing (there is no continuous monitoring or the measuring system can be broken for a while) the forecasting of the load can be performed using the correlation studies. The starting point of the algorithm is statistical analysis of the active and reactive curves of the substations and utilization of a fuzzy linear regression model. This can be made for different time windows (window 24 h, window 7 h, etc). The window 24 h can be used successfully to estimate the hourly load on any substation. The other time window (7 h) can be used in the peak load estimation of the substations, using the maximum value of the active power recorded in a reference substation. Findings – The numerical data show that the fuzzy correlation models can be used with very good results for determination of the peak load corresponding distribution substations, and further with the state estimation of the system. In this study, the influence of the time window size is presented in detail, and the fuzzy correlation models for the peak loads from the distribution substations are obtained. Originality/value – Starting from the correlation theory, a method of fuzzy modelling of active and reactive powers from the substations of an electrical distribution system is proposed. [ABSTRACT FROM AUTHOR]

Purpose - This paper seeks to present a fully digital, real-time (RT) hardware-in-the-loop (HIL) simulator on PC-cluster, of electric systems and drives for research and education purposes; to use the developed system to conduct several motor drives implementation and to evaluate the motor and the control algorithm performance in RT. Design/methodology/approach - This simulator was developed with the aim of meeting the simulation needs of electromechanical drives and power electronics systems while solving the limitations of traditional RT simulators. This simulator has two main subsystems, software and hardware. The two subsystems were coordinated together to achieve the RT simulation. The software subsystem includes MATLAB/Simulink environment, a C++ compiler and RT shell. The hardware subsystem includes FPGA data acquisition card, the control board, the sensors, and the controlled motor. Findings - The complexity of RT implementation of motor drives is greatly reduced by utilizing this simulator. The detailed operation and implementation of this simulator are presented, together with test results and comparisons with simulated virtual environment for a permanent magnet dc and induction motors (IM). The simulator performance is adequate for both open and closed loops motor drives. The simulation time step is limited by the system Master/Target CPU''s speed, the communication network type, and the complexity of the control algorithm. Practical implications - A typical application for this system is to select and evaluate the performance of electric motors for a hybrid electric vehicle in a real vehicle environment without actually installing that component in the real vehicle. Originality/value - The use of the developed RT simulator to achieve HIL simulation allows rapid prototyping, converter-inverter topologies testing, motors testing, and control strategies evaluation. The transition from simulated virtual environment to the HIL mode can be performed by replacing the model of the physical system (e.g. motor) with the DAQ blocks to represent the channels connected to the physical system sensors. The use of a single environment for both simulation and HIL control provides a quick experimentation and performance comparison between the real and simulated systems. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to present a new model to study inter-turn short circuit faults in a permanent magnet synchronous machine. Design/methodology/approach - The machine is modeled by using classical two-axis theory, and the equations are modified to take into account the stator inter-turn faults. A state space form of the system is presented for dynamic simulations. Findings - The machine model is global and can work in both normal and fault conditions due to a fictitious resistance in the winding circuit. Various simulation results have been presented indicating the fault instant and its corresponding effect. Validation is carried out by transient time finite element simulations. Originality/value - The model can serve as a step towards development of fault detection and diagnosis algorithms. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to present a frequency domain technique for the recognition and location of winding movements and mechanical deformations in power transformers. Both, axial and radial coil movements, as well as changes in clamp pressure will be studied. Design/methodology/approach - The developed algorithm is based on using a distributed s-domain parameter equivalent network, which is cascaded with other sections to constitute a generalized model. The frequency domain transfer admittance is used as the main criterion to recognize, identify and locate the winding movement and deformation. Findings - In order to reduce the number of failures due to winding movements and deformations, it is suggested to measure and store the transfer admittance over frequency range 0-10?MHz region at normal operation as saved data for comparison with the corresponding data during failure. With the proposed technique, the type and the location of eventual displacement, as well as the number discs involved can be identified. Research limitations/implications - Although the simulation was based on real experimental data adopted from the literature, the algorithm should be tested for real transformers. Several checks have been conducted in order to validate the mathematical model. Originality/value - A relatively simple mathematical model has been presented. It can be used for any transformer, to check the integrity of the winding in order to meet certain degree of equipment safety and reliability. [ABSTRACT FROM AUTHOR]