Method of parametric analysis of reciprocating electric generators with permanent magnets

A method for the parametric analysis of electric generators of reciprocating motion with permanent magnets has been developed, which allows revealing the values of the parameters of the magnetic circuit (cross-sectional area) and the working winding (number of turns) at a given value of the efficiency, providing a minimum specific gravity of the generator. The method of parametric analysis of electric generators of reciprocating motion with permanent magnets consists of three stages. The first and second stages are the electromagnetic calculation of the generator: at the first stage, the main geometric dimensions of the magnetic system and the parameters of the working winding of the generator are determined; at the second stage, the verification of the electromagnetic calculation of the generator, calculation of the nominal mode, calculation of the efficiency and assessment of the thermal state of the generator are fulfilled. At the third stage, a parametric analysis of electric generators of reciprocating motion with permanent magnets with specified constraints is carried out, as well as the refinement of the geometric dimensions and configuration of the magnetic system of the generator using a two-dimensional finite element model of the magnetic field. As a result, to ensure better use of the electrical steel of the magnetic circuit of the generator and thereby reduce its mass, the most saturated areas and areas, which are characterized by low values of the magnetic field strength, are determined. Distinctive features of the proposed technique are: the use of a minimum specific gravity of electric generators of reciprocating motion with longitudinal, transverse or combined changes in the magnetic flux passing through the working winding as an objective function; combined approach to electromagnetic calculation; taking into account the influence of the operating temperature on the parameters of the permanent magnet, as well as overheating of individual parts of the generator.

Electromagnetic calculation and kinematics analysis of multi-DOF motor with air-floation

In view of the fact that the transmission mode of the multi-DOF motor hinders its further development, the gas bearing is applied to the multi-DOF motor to form a new structure of the multi-DOF motor with air-floation (AMM). AMM not only improves the motor’s motion characteristics and transmission performance, but also basically does not cause environmental pollution. AMM uses porous static pressure gas bearing as the support structure, and completes the multi-DOF movement by controlling the energizing strategy of the coils. This paper introduces the structure of AMM, analyzes the basic working principle of AMM, and solves the air gap magnetic field; the kinematics model of the motor is established, the motion of the motor is controlled with the help of virtual simulation software, and the motion trajectory of the motor is obtained through the marked points of the output shaft. Finally, the AMM was verified by experiments, the error of experiment and simulation was controlled at 5%, and the kinematics characteristics of the motor met the design requirements. The research results provide a new idea for the development of multi-DOF motor.

Design, fabrication and testing of a coated conductor magnet for electrodynamic suspension

Coated conductor magnet, as the onboard magnet of the electrodynamic suspension (EDS) train, is deemed promising due to its relatively high operating temperature, low cooling cost, and good mechanical tolerance, making the liquid-helium-free high-temperature superconducting (HTS) EDS train possible. In order to promote the progress of the HTS EDS train, this work aims at designing, fabricating and testing a coated conductor magnet as the onboard magnet of EDS train. The HTS magnet is designed with the comprehensive considerations of the electromagnetic calculation, thermal-mechanical coupling analysis, as well as the heat load estimation. The magnet is conduction-cooled without any coolant. A radiation shield was used to reduce the heat leakage, enabling the cryogenic system to provide a better low-temperature environment for the magnet. Through a deliberate design, the magnet was fabricated, including two HTS coils and the tailored cryogenic system. Afterwards, the electromagnetic and thermal performances of this magnet were tested and analysed in detail. It was proven that the magnet can be cooled to below 15 K; besides, the magnet has been successfully charged to 240 A. Further increase in the current is possible because of the high safe margin of the critical currents for both the HTS magnet and its current lead, although a slight performance degradation was observed on two double-pancake coils inside the magnet. The present study will provide useful implications for the design and application of onboard HTS magnets in EDS train.

Approach for the Model and Parameter Selection for the Calculation of Induction Machines

The solution of multiphysical problems in the field of electrical machines is a complex task that involves the modeling of a wide variety of coupled physical domains. Different types of models and solution methods can be used to model and solve the individual domains. In this paper a procedure for the methodical selection of the most suitable model for a given multiphysics task is presented. Furthermore, an approach for the selection of the most suitable variable machine parameters for a design optimization is presented. The model selection is presented on the basis of the electromagnetic calculation of an induction machine. For this purpose, models of different value ranges and levels of detail, such as analytical and numerical ones, are considered. The approach of the model selection is explained and applied on the basis of a coupled electromagnetic-thermal simulation of an exemplary induction machine. The results show that the model selection presented here can be used to methodically determine the most suitable model in terms of its value range, level of detail and computational effort for a given multiphysical problem.

Development of the Electromagnetic Calculation Software Package for a Synchronous Motor Based on the Field-Circuit Combination Algorithm

Nowadays, domestic motor manufacturers often use high-speed circuit and magnetic circuit parameters in engine models. In addition, the calculation accuracy is low and cannot fully meet the requirements of a modern engine design. The field-circuit combination algorithm is based on electric field analysis, which avoids many rough assumptions and empirical formulas; its calculations are more accurate and reliable than traditional algorithms. It is used to analyze and calculate the steady-state operating conditions and characteristics of motors, which can effectively improve the design level of China’s boss synchronous motors. This article mainly introduces software algorithms and auxiliary FDTD methods. In this article, we use the field-circuit coupling algorithm to develop an electromagnetic calculation software package for synchronous motors and establish a mathematical model for the potential field-circuit coupling algorithm. We use the cassette electromagnetic calculation program to solve the model, evaluate the synchronous motor, and use historical data to modify the model and improve the accuracy of the development-state evaluation of the electromagnetic calculation software package for the synchronous motor based on the motor electromagnetic circuit coupling algorithm. The experimental results of this article show that the field circuit combination algorithm increases the development of the electromagnetic calculation software package for synchronous motors by 55% and reduces the false alarm rate and false alarm rate. Finally, by comparing the phases of traditional algorithms, we analyzed the excitation circuit combination algorithm to calculate the parameters and performance of the synchronous motor.

Development of Refined Electromagnetic Models of Reciprocating Electric Generators with Permanent Magnets

The analysis of scientific papers devoted to the mathematical description of electric generators of reciprocating motion with permanent magnets demonstrated that the proposed mathematical models of this type of generators are based on the theory of magnetic circuits. Such mathematical models are based on a simplified representation of the magnetic system and the magnetic field in the form of a magnetic circuit with corresponding magnetic conductivities. However, unlike traditional rotary type electric machines, electric generators of reciprocating motion have a number of features, the omission of which in mathematical modeling causes the increase of the cost of their creation (due to the duration of the design and experimental refinement of the generators). Therefore, at the initial stages of electromagnetic calculation and solving optimization problems, it is necessary to use adequate mathematical models to improve the accuracy of calculations of the parameters of these generators. For this purpose, a mathematical model based on field theory can be used; however, its main drawback is the complexity of its application for solving optimization problems. In this regard, to improve the accuracy of calculations of the parameters of electric generators of reciprocating motion with permanent magnets, it is proposed to use refining coefficients (coefficients of scattering and buckling of the magnetic flux) in mathematical models based on the theory of magnetic circuits. The authors have developed refined electromagnetic models of electric generators of reciprocating motion with permanent magnets, which make it possible to obtain the main parameters of generators at the initial stages of electromagnetic calculation and when solving optimization problems with acceptable accuracy. A distinctive feature of the refined electromagnetic models of generators is the consideration of the scattering and buckling coefficients of the magnetic flux in the magnetic system that change during the simulation.

Research on wide-band electromagnetic scattering characteristics of random distributed objects using monte carlo method

In the engineering applications, the distribution of objects is mostly random. Therefore, scattering analysis of randomly distributed objects has been one of the important problems in broadband electromagnetic calculation field. To resolve the problem, the Asymptotic Waveform Evaluation technique in conjunction with Monte Carlo Method is presented. First, the stochastic distribution is modeled by the Monte Carlo Method, and then the Asymptotic Waveform Evaluation technique using Padé approximation is utilized to achieve the Radar Cross Section at a wide frequency band. Numerical results show that the Asymptotic Waveform Evaluation technique can solve the random distributed object problems efficiently and accurately.

Optimizing AC Resistance of Solid PCB Winding

At high frequency, power losses of a winding due to eddy currents becomes significant. Moreover, the skin and proximity AC resistances are influenced by the width of printed circuit board (PCB) conductors and distance between the adjacent tracks which causes many difficulties to design windings with lowest AC resistances. To clarify this phenomenon, this paper focuses on modeling the influence of skin and proximity effects on AC resistance of planar PCB winding, thereby providing guidelines to reduce the winding AC resistance. An approximate electromagnetic calculation method is proposed and it shows that when the winding proximity AC to DC ratio ( F p r o x i m i t y ) is equal to 1 3 the AC on DC ratio caused by skin effect ( F s k i n ) , the winding is optimized and it has lowest AC resistance. 3-D finite element simulations of 3, 7 and 10-Turn windings, which are divided into 3 groups with the same footprint, are presented to investigate the lowest AC resistance when the track width varies from 3 mm to 5 mm and the frequency range is up to 700 kHz. In order to verify the theoretical analysis and simulation results, an experiment with 3 simulated groups, (9 prototypes in total) is built and has a very good fit with simulation results. Experimental results show that at the optimal width, the AC resistance of the windings can be reduced up to 16.5 % in the frequency range from 200 kHz to 700 kHz.