Search

A method to optimize transverse flux induction heating (TFIH) inductor for a uniform temperature distribution is presented. The trained network can be used to provide a good guesses value of the temperature dependent parameters for each finite element and an initial value for temperature field solution, which speeds up the iterative solution process for the nonlinear coupled electromagnetic thermal problems.

This paper presents a new electromagnetic vibration-powered generator. In the generator, the moving mass has a sandwich structure, consisting of two axially magnetized annular permanent magnets and one soft magnetic “pole piece.” The purpose of using the soft magnetic pole is to increase the effective flux linkage of the generator and to increase the output voltage of the generator. The generator makes use of a “magnetic spring,” which gives advantages such as ease of construction, ease of tenability, and less prone to fatigue as opposed to a mechanical spring. The mathematical model of the generator was built. The magnetic field distribution of the designed generator was analyzed by means of finite-element method. The prototype generator was built and tested with a force control electromagnetic shaker. Tests results of output waveforms have shown good agreement with simulation results. The open circuit RMS voltage of the presented generator is 662.0 mV, which increases by an additional 13.5% the one of conventional structure, at a resonance frequency of 15 Hz and an amplitude of 3 mm. [ABSTRACT FROM PUBLISHER]

This paper presents a novel current sensor, which includes a giant magnetoresistance (GMR) chip, a toroidal magnetic core, and a feedback winding on the core. The mathematical model of the sensor was built, which was used to analyze the influence factors of the closed-loop current sensor. The closed-loop configuration with the magnetic core and the feedback winding improved the sensitivity of the sensor, eliminated the offset and drift related to temperature of the chip, and greatly reduced the error caused by magnetic hysteresis phenomenon. The simulation and test results showed that the novel current sensor has very low linear error (less than \pm 0.7%). The designed sensor can measure frequency of currents up to 100 kHz. The current sensor has high linearity with the range from 10 mA to 20 A. [ABSTRACT FROM PUBLISHER]

As giant magneto resistive (GMR) effect based current sensors are susceptive to stray magnetic fields, this paper proposes a GMR current sensor with a magnetic shielding. Magnetic shielding effectiveness and magnetic gain coefficient of the shielding are analyzed by finite element method (FEM), and some concerned parameters affecting the shielding effects are also discussed. In order to achieve accurate measurement for ac and dc, this paper proposed two methods for providing bias magnetic field. One method is using a coil winding and the other is using permanent magnet. Based on theoretical analysis and simulation results, a prototype was designed. Hysteresis effects on the sensor, the sensitivity of the GMR current sensor, and relative error of the measurement of the current sensor with and without magnetic shielding were tested and compared. The two methods for producing bias magnetic field were also tested and discussed. The designed GMR current sensor has the advantages of high sensitivity and accuracy, low nonlinear error (0.8%). It can measure currents from dc up to 200 kHz with the nominal primary current value of 20 A. [ABSTRACT FROM PUBLISHER]

The development of domestic HVDC transmission system needs the HVDC transformer to perform better. A large amount of higher harmonics will be generated in the load current when the transformer works in a converted way. Due to this, the eddy current field is a nonlinear and non-sinusoidal one. Based on Visual Basic 6.0 and MagNet, special software for magnetic leakage field analysis and stray loss calculation was written. Using the special software, the distribution of magnetic leakage field was studied and the stray loss of the transformer was calculated. [ABSTRACT FROM PUBLISHER]

This paper presents a new electromagnetic vibration-powered generator. The input-output mathematical model of an axial magnetization annular permanent magnet spring is built. Taking advantage of the model, the characteristic curve of the magnetic force versus the displacement is obtained. Wires were wound both inside and outside of the annular permanent magnet to form an inner coil and an outer coil, respectively. The characteristic curve of the magnetic force, the natural frequency, the output voltage waveforms of the outer coil and the inner coil, and the magnetic field distribution of the designed generator have been simulated using the Finite Element method (FEM). Tests results of the output waveforms have good agreement with the simulation results. The maximum output power of the designed vibration-powered generator is 28.3 mW, and the open circuit RMS voltage is 5.1 V at an vibration frequency of 20 Hz and an amplitude of 5 mm. [ABSTRACT FROM PUBLISHER]