Influence of the Shape of the Input Pulses on the Characteristics of Hybrid Electromagnetic System with Magnetic Flux Modulation
1Department of Electrical Apparatus, Technical University of Sofia, Bulgaria; 2Department of Electrical Engineering, Technical University of Sofia, Plovdiv Branch, Bulgaria; 3Department of Electrical Supply, Electrical Equipment and Electrical Transport, Technical University of Sofia, Bulgaria
New construction of hybrid electromagnetic systems with magnetic flux modulation is studied. For computer modelling of the construction COMSOL software is used, where coupled electromagnetic field – electric circuit analysis is carried out. Two input coils connected to the pulsed power supply are used to change the path of the generated by the permanent magnets constant magnetic flux. Input pulses with different shapes are applied to the input coils and signals in the output coils are obtained and compared. The main purpose of the work is to find the shape of the input pulses which leads to higher output power in comparison with the other shapes.
Modeling and Analysis on the Five Degrees of Freedom Integrated AC-DC Hybrid Magnetic Bearing
1Huaiyin Institute of Technology, China, People's Republic of; 2University of Technology Sydney, NSW 2007, Australia
To reduce the volume, weight and cost of high-speed magnetic levitation motor system, a novel five-degree-of-freedom (5-DOF) integrated AC-DC hybrid magnetic bearing (HMB) is researched. Firstly, the structure and suspension mechanism of proposed HMB is introduced, and then the mathematical models of suspension force are deduced by magnetic circuit method. Finally, the main parameters of the experimental prototype are designed. The magnetic circuit is analyzed by finite element method, and the relationships between currents and suspension forces are calculated. The correctness of suspension mechanism and mathematical models are verified.
Design and Optimization of a Bidirectional Flux-modulation Machine for AC/DC Hybrid Power Supplies
The Hong Kong Polytechnic University, Hong Kong S.A.R. (China)
A novel DC/AC hybrid power supply system that utilizes wind power is proposed in this paper. A special designed brushless permanent magnet machine with bidirectional flux-modulation effect is adopted as the key part of the power supply system. The novel power system has a compact structure which possesses two sets of electric port, with one for the AC power supply and another one for DC power supply. The key is to control the position of the inner rotor, and hence the induced voltage in the two sets of armature windings will be changed accordingly due to bidirectional flux-modulation effect. The induced voltage due to flux modulation effect can be used to offer DC power supply after the rectifier and the induced voltage due to outer rotor can be used to offer AC power.
Analytical Calculation of Air-Gap Magnetic Field in Novel Flux Reversal Permanent-Magnet Machines with Asymmetrical Stators
1Southeast University, Nanjing, China; 2The Hong Kong Polytechnic University, Hong Kong, China
This paper presents an accurate analytical model for the open-circuit magnetic field in asymmetrical-stator pole flux reversal permanent-magnet (ASP-FRPM) machine by taking the slotting effect into account. The air-gap magnetic flux density is calculated by combining the subdomain model and Schwarz-Christoffel (SC) transformation. The original contribution of the model lies on that the slotting effect between the rotor and asymmetric stator are considered in the analytical model. The accuracy of the method is verified by the finite element (FE) results. Finally, a prototype is fabricated and the experimental results will be given in the full paper.
Loss Calculation for Multiphase Induction Machine Under Open-Circuit Fault Using Field-Circuit Coupling Finite Element Method
Zhejiang University, China, People's Republic of
This paper focus on the loss calculation for multiphase induction machine (IM) operating under fault-tolerant condition through filed-circuit coupling finite element method (FEM). Both one phase and two phases open-circuit faults of a 7-phase IM are researched and different spatial positions of the fault phases are taken into consideration. The magnitudes and phase angles of the residual phases current are deduced based on two constraint conditions, including equal magnitude of residual phases current and minimum stator copper loss. Then the time-stepping electromagnetic fields of the 7-phase IM under different faults conditions are calculated based on rotor field-oriented control (RFOC). The Joule loss and iron loss are calculated and the calculation results are useful for optimization design of fault-tolerant control strategy.
A Novel AC-DC Five Degrees of Freedom Hybrid Magnetic Bearing With Inclined Axial Air-gaps
1Huaiyin Institute of Technology, China, People's Republic of; 2University of Technology Sydney, NSW 2007, Australia
In order to reduce the volume, cost and axial length of high-speed magnetic suspension direct drive system, a five degrees of freedom (DOF) AC-DC hybrid magnetic bearing (HMB) with inclined axial air-gap is researched. Firstly, the structure and the 5-DOF suspension mechanism of proposed HMB are analyzed. Then the five-DOF suspension force mathematical models are deduced by the equivalent magnetic circuit method. The main parameters of the prototype are optimized. Finally, the magnetic circuit is analyzed by the three-dimensional finite element method, and the relationships between the suspension forces and the mathematical models are calculated, which verifies the correctness of the suspension mechanism and the suspension force mathematical models.
Coupling between an analytical tool and stator current sheet to test the inherent impact of armature winding distribution using FEM
Univ. Lille, Arts et Metiers ParisTech, Centrale Lille, HEI, EA 2697 - L2EP -Laboratoire d’Electrotechnique et d’Electronique de Puissance F-59000 Lille, France
The study of the inherent impact of different winding distributions using FEM can be complicated when taking into account the stator slots as it introduces both constraint and reluctance variation of the air gap. To avoid this fact, a ‘current’ sheet spread all around the inner stator surface can be used while being coupled with an analytical tool that supplies it by the given MMF values.
Novel Strategy Combining Low-to-High Frequency Model to Consider IPMSM Characteristics
1SUNGKYUNKWAN UNIVERSITY, Korea, Republic of (South Korea); 2CHOSUN UNIVERSITY, Korea, Republic of (South Korea); 3DONGGUK UNIVERSITY, Korea, Republic of (South Korea)
The high frequency (HF) Common-mode voltage is generated by the arrangement of the ac motor winding and inverter pulse-width modulation (PWM) control. Moreover, it is the cause of various problems which are corrosion of bearing and electromagnetic interference (EMI). This paper, to deal with the problems, propose the universal equivalent model, through the combination of Shaft voltage equivalent model and the HF model. The shaft voltage equivalent model approach is based on the design parameters of motor which have distributed winding. The HF model is based on the developed low-frequency T-equivalent circuit including high-frequency effect using the resonance frequency Finally, the result of universal equivalent model is compared with the numerical result about shaft voltage and current, and measurement data using network analyzer about impedance parameter.
Sensitivity-based Parameter Extraction of 3D Transient Magnetic Problems
1ElectroMagneticWorks Inc.; 2ElectroMagneticWorks Inc.; 3ElectroMagneticWorks Inc.; 4École de Technologie Supérieure
This paper investigates the extension of a recent technique for parameter extraction, namely the sensitivity analysis, to 3D Transient magnetic problems. For this purpose, we present few application case studies where we compare the dynamic inductance and resistance values computed using the mentioned method with their counterparts obtained using analytical and/or experimental results.
Simplified Mathematical Model for Evaluating Influence of Inter-turn Fault on PMSM
Incheon National University, Korea, Republic of (South Korea)
To evaluate the influence of an inter-turn fault on permanent magnet synchronous motors, various fault models have been utilized. However, since the models are require information on many parameters and solving complex equations, they are inappropriate in terms of time efficiency. Thus, this study proposes a simplified mathematical model by using typical features of the fault.
A general method to compute the electric flux lines in the slots of electric machines for the evaluation of partial discharges risk
Nowadays, on board electric machines of higher specific power powered by faster inverters represent a real challenge in designing the electrical insulation system (EIS). The electric stress on the stator winding is increased and thus partial discharges (PD) are more likely to appear. The Paschen’s criterion is widely used to evaluate PD risk. This paper presents a general method to compute the electric flux lines in the slots of electrical machines. A 2D model of an electric machine slot is solved in term of electric scalar potential. Then, from the nodal scalar potential solution, electric flux lines are located inside the slots. Thus, the Paschen’s criterion is applied by taking into account the real flux lines length. Some applications are presented to highlight the usefulness of the method to solve industrial problems.
A routine for improvement of coil turns distribution for permanent-magnet microgenerators used in vibration energy harvesters
Opole University of Technology, Poland
A design routine improving distribution of separate turns within a coil for better exploitation of the magnetic flux in a permanent-magnet microgenerator used in a vibration energy harvester is presented. The distribution of the magnetic field is determined using the
3-d integral formula. Initially the coil is considered as a cluster of loops formed by separate turns. The routine decides whether the loops are valid or void based on the simulated performance of the generator supplying resistive load via power converter. The proposed
procedure considerably increases the output power generated by the system which is confirmed experimentally.
An Analytical Approach to Estimate the Cogging Torque in Segmented stator Synchronous Permanent Magnet Machines with large Gaps
This paper presents a new analytical model to determine the cogging torque of unconventional permanent magnet machines with segmented stator. This model is based on the superposition method. The calculation of the cogging torque is based on two basic calculations. The first one is the calculation of the cogging torque of a slotless machine with only one gap. The second one is the calculation of the cogging torque of a non-segmented slotted machine. These basic calculations and the calculation of the complete slotted and segmented machine cogging torques are validated using comparison with results obtained by numerical computation by 2D Finite Element Method.
Determination of the maximum size of finite elements in eddy-current layers of rotating electrical machines
1Instituto Tecnologico de Morelia, Mexico; 2Universidad Nacional Autonoma de Mexico, Mexico; 3Universidad Autonoma Metropolitana-Azcapotzalco, Mexico
A proper determination of the maximum size of the elements, involved in the finite element analysis, is obtained for moving eddy-current layers of electromagnetic devices with moving components, such as electrical rotating machines. The problem of diffusion of electromagnetic field into a moving magnetic slab is solved analytically and numerically by employing the Galerkin method, with appropriately established boundary and initial conditions. A rigorous analysis of the analytical solution shows that the maximum size of elements, that do not lead to stiffness phenomenon, depends on both the velocity of the moving part and frequency of the incident electromagnetic field.
Improvement of Magnetic Shielding for Transformer Tank Based on the Magnetic Flux Characteristics at Shielding Ends
1Tsinghua University, China; 2Siemens Transformer (Jinan) Co. Ltd., China
Magnetic shielding is generally laid on transformer tank and clamping frames to reduce the eddy current loss in the tank, yet the flux concentration phenomena caused by the magnetic shielding is not well paid attention by designers. According to the simulation results of the accustomed shielding structures, we noticed that the flux density near the end of shielding plates is relatively very high. Thus an idea is proposed that regions with lower flux density before shielding construction may also need to be shielded, and the shielding should be made to closed path or loop, i.e., the shielding plates in different directions should be connected each other, or the end of plates should be bent to the core surface. The aim of all these measures is to avoid the flux entering the transformer tank. The improved structure of the shielding can obviously reduce the loss of the tank, which can mitigate the extent of local overheating. The effect of the magnetic shielding is calculated by the finite element analysis.
3D Hybrid Model of Axial Flux Motor Accounting Magnet Shape
Laboratoire Laplace, France
This paper presents a generalization of an analytical model of an axial flux permanent magnet machine to any magnet shape. It uses an existing model that computes the 3D magnetic flux density by separation of variables and finite difference method. The original magnet shape is modified by adding a radial dependence to the arc pole. It will be shown that this radial dependence has no impact on the resolution of the problem. As an example, the model will be computed for a circular magnet shape and will be compared to a finite element analysis.
A Neural Network based Electromagnetic Simulator
McGill University, Canada
Simulating electromagnetic problems using the finite difference method or the finite element method can lead to large systems of linear equations which need to be solved. Often in the design process, while fine tuning, few system parameters are changed, while the overall system remains largely the same. The system is simulated repeatedly to find the optimal parameters, which can be a time-consuming process. In this paper we propose a new method that uses a neural network trained on a lot of variations of similar problems that can be used to get a quick estimation of the system’s response to small changes in the parameters. Rather than attempting to solve the electromagnetic problem with a neural network, which has been done before, we focus on getting an extremely fast, but also accurate estimation. A concrete example problem is demonstrated through the simulations of a coaxial a cable with varying inner conductor shapes. Details about the design of the neural network regarding the choice of hyperparameters and the network’s architecture are given. Additionally, an evaluation shows the performance of different proposed neural network architectures.
Optimization Design of Oil-immersed High-Speed Permanent Magnet Synchronous Motor (PMSM) Based on Test Model
Wuhan Institute of Marine Electric Propulsion, China, People's Republic of
This paper studies the viscous loss and electromagnetic vibration of an oil-immersed high-speed PMSM based on test model. For a fully oil-immersed high-speed PMSM, its rotor loss and electromagnetic vibration are quite different from those of conventional motors operated in air, which is paid to little attention, its accurate calculation and analysis are very important for performance and scheme design, especially under the condition of high power density and low noise requirements. Firstly, the rule and distribution of the viscous loss of an oil-immersed motor varying with oil temperature and motor speed by the experimental method are discussed in this paper, a new formula of calculating viscous loss is obtained by modifying the calculation formula of friction loss between rotor and lubricating oil derived by a combination of basic theory of hydrodynamics based on the experimental data mentioned above, some measures and topology structure design are provided to reduce rotor loss and motor vibration. Secondly, the electromagnetic scheme of two 10kW 4431RPM-6451RPM oil-immersed PMSM for oil pumps are optimized and designed by field-circuit coupling electromagnetic finite simulation. Finally, the two prototypes are built and tested, the experiment results show that the test and simulation calculation are in good agreement, which verifies the correctness and feasibility of the scheme and method.
Characteristic Analysis of Magnetic-Geared PMSM for Traction System according to Permanent Magnet Shape
1Korea National University of Transportation, Korea, Republic of (South Korea); 2Hanyang University, Korea, Republic of (South Korea)
In this paper, various characteristics of MG-PMSM for traction system were analyzed according to permanent magnet shape. First, small-scale MG-PMSM models were designed. Surface permanent magnet (SPM) type and Interior permanent magnet (IPM) type were considered as permanent magnet shapes. In addition, a comparative analysis of the three 1kW-class MG-PMSM models, in terms of electromagnetic properties, was performed to assess their general performance. The overall electromagnetic properties of the three designed models were similarly derived. The cogging torque and the rated torque characteristics of the IPM (V) type model were the best in comparison with the other models.