Jiaxin You

A Type of Subsection Model for a Permanent Magnet Bar and its Leakage Permeance Calculation Method in an Open Magnetic Circuit

The equivalent model of a permanent magnet (PM) plays an important role in electromagnetic system calculation. A type of subsection model for a PM bar is established, to improve the accuracy of the traditional equivalent circuit method. The mathematical expression, and its end verification condition, are presented. Based on the analytical method and finite element method, the leakage permeance calculation of a PM bar in an open magnetic circuit is investigated. As an example, for a given certain type of PM bar, the magnetic flux of each section is validated by experiment, and by simulation. This model offers a foundation for building a high accuracy equivalent magnetic PM model in an electromagnetic system.

Structure classification of electromagnetic relays and comparison of typical magnetic system containing permanent magnet

The electromagnetic relays have lots of structures and are applied widely in the automation control system in aerospace. Firstly, the structures of aerospace electromagnetic relays (AEMR) were classified. According to the structure arrangement, there are three layers, two layers and one layer structures; from electromagnetic system, there are clapper type, balance armature type, polarized magnetic system and balance force magnetic system; from armature returning mode, there are spring returning, permanent magnet returning, permanent magnet magnetic circuit returning and polarized magnetic circuit returning modes. All of these structures were compared separately. Then, the equivalent magnetic circuit model of the typical polarized magnetic system and balance force magnetic system are founded. The ultimate difference between these magnetic systems was illuminated based on the polarized magnetic system criterion. The research conclusions can be used to direct the design of AEMR.

Research on the distribution thermal FEM model for an enclosed isolated phase bus-bar in short-circuit condition

As the first power transmission part of synchronous generator output, the thermal stability of the enclosed isolated phase bus-bar (EIPB) is important for the working safety of the power system. The thermal stability of large synchronous generator-side EIPB is hard to be analyzed or calculated because of the complex structure and the large size of EIPB in the power system. In this paper, a new co-simulation method of EIPB is studied. Taking a certain type of EIPB in power system as example, the co-simulation method is applied. Based on the co-simulation method, the sub-segment FEM models are established and simulated. The temperature distribution in joint surfaces is transmitted between sub-segment FEM models. The temperature distribution of EIPB in short-circuit current under the cooling condition is calculated. The minimum ventilation rate in different environment temperature and different short-circuit current is calculated.

Analytical Method for the Magnetic Field Line Distribution of a Fan-shaped Permanent Magnet and the Calculation of Leakage Permeance

Leakage permeance of a permanent magnet (PM) is an important factor for improving the accuracy of electromagnetic device calculations based on a magnetic equivalent circuit (MEC). For PM leakage permeance calculations, the traditional simulation method of finite element analysis (FEA) and the lumped parameter analytical method (LPAM) have been considered; it was found that FEA has the disadvantage of a long calculation time and LPAM has low accuracy. The magnetic field lines distribution analytical method (MFLD) is proposed in this paper in order to raise computational efficiency and keep accuracy within a certain range. The electromagnetic features of open circuit fan-shaped PMs are presented by MFLD and finite element analysis (FEA) is adopted to match the MFLD results. In order to verify the validity of the proposed method in a magnetic system, the working points of PMs in an electromagnetic actuator are calculated, and the numerical results compared with the experimental results.

Steady Temperature Rise Analysis of Non Segregated Phase Bus Based on Finite Element Method

In the design and analysis of Non Segregated Phase Bus (NSPB), steady temperature rise calculation is very important especially for the bolt-joint contact structure NSPB. In order to ensure the safety of such products, taking a certain type of NSPB for example, finite element method (FEM) calculation model of NSPB is built based on thermal transfer theory, the maximum temperature rise of NSPB is calculated under different DC and AC loads within the bus working range, the temperature distribution of contact area is simulated; and the temperature correspondence relationship of DC-AC is discussed; the NSPB temperature rise has been tested and compared with the experiment results, the validity of NSPB FEM calculation is verified.

A Type of Attractive Force Calculation Model of Polarized Relay Based on Nonlinear Permanent Magnet Bar Subsection Model

In polarized relay, the armatures are sometimes made of permanent magnet (PM). The attractive force calculation is very important in the design and analysis of polarized relays. For some polarized relays which use less expensive permanent magnet bars that have nonlinear magnetic properties, the modeling of such nonlinear permanent magnet (NPM) bars is particularly important to the design of relay contact force, operation speeds and subsequent effects on switching performances. In this paper, an Equivalent Magnetic Calculation model of a NPM polarized relay is built based on a subsection model. The subsection interfaces of NPM are analyzed and the leakage permeance between the armature and yoke is calculated. Then the electromagnetic force is calculated on various rotation positions. This is compared with a finite element method (FEM) and the accuracy of the subsection calculation model is verified.

Shielding Design for Current Sensor of Excitation System Based on 3-D FEM

In an excitation system of a certain type synchronous motor, current sensor for detection and protection often works under abnormal conditions. It leads to inability to play the role of the normal current detection, or even false tripping down the serious accidents. This failure is mainly generated by electromagnetic interference. Finite element analysis software is used to build the main circuit 3-D model of excitation system, by analyzing electromagnetic interference (EMI). Major source of interference is located. A method of installation shielding sleeve is designed, through theoretical calculations shield manufacturing materials are determined, and the effectiveness of this shielding design is clarified based on the existing finite element model. Through experiments the correctness based on the finite element method of such analysis is correct is verified.