Magnetic circuit

About: Magnetic circuit is a research topic. Over the lifetime, 15707 publications have been published within this topic receiving 118099 citations.

Dual-Axial Motion Control of a Magnetic Levitation System Using Hall-Effect Sensors

Abstract: This paper presents a new methodology to determine the position of a magnetically guided robot (MGR) in horizontal planes using magnetic flux sensors. This position determination methodology can be used independently as well as in collaboration with optical sensors in the case of the optical blockage. A combination of linear Hall-effect sensors (two sensors for each axis of motion) was employed to measure the magnetic flux in the MGR's working space. A configuration of several electromagnets was used as a source of magnetic field, and an analytical model of the system is developed. The MGR's position was determined based on the polynomial relation between the Hall-effect sensors' output and the location of the minimum magnetic potential energy point in horizontal planes. Using the cross-validation method, it was found that a fourth-order polynomial model could accurately predict the MGR's position. Experiments were conducted on a horizontal plane to validate the performance of position estimation using the magnetic flux sensing method. The accuracy of the position determination method was 0.4-mm root-mean-square errors in both the x - and y -direction over 8 × 8 mm2 working area. This paper also experimentally validates a combined optical-magnetic position determination technique for the motion control of a magnetically guided robot in optical blockage conditions as unknown environment that can be used as a promising replacement of X-ray and ultrasound techniques.

Dynamoelectric machine with diamagnetic flux shield

Abstract: An AC electrical machine which includes a superconducting, diamagentic flux shield cylinder enclosing the stator windings such that the magnetic flux produced by the machine's rotor is bottled within the flux shield.

A Family of Zero-Voltage-Switching Magnetic Coupling Nonisolated Bidirectional DC–DC Converters

Abstract: This paper proposes a family of magnetic coupling nonisolated bidirectional dc–dc converters, which can achieve soft-switching operation in both power flow directions with a simple auxiliary circuit. Compared with conventional zero-voltage-transition converters, the additional resonant inductor is eliminated and magnetic core number is reduced. Therefore, both high efficiency and low cost are achieved. First, a general zero-voltage-switching (ZVS) magnetic coupling structure is proposed for a bidirectional buck/boost converter, based on which 13 different ZVS topologies with different connections of auxiliary circuit are derived. It is very beneficial in practical industrial applications because engineers can choose an optimal one according to converter performance characteristics, and the topology derivation methodology can be easily extended to other bidirectional dc–dc converters. Second, based on the general structure, operation principle and performance characteristics of all proposed topologies are simultaneously obtained, which can facilitate topology comparison and selection processes. Finally, in order to verify the effectiveness of theoretical analysis, design considerations and experiment results of a 500-W prototype circuit are demonstrated.

Through-Wall Excitation of a Magnet Coil by an External-Rotor HTS Flux Pump

Abstract: High-temperature superconducting (HTS) magnet systems conventionally require normal-conducting current leads, which connect between the HTS circuit and an external power supply located at room temperature. These current leads form a thermal bridge across the cryostat wall, and they represent the dominant heat load for many magnet applications. The use of a superconducting flux pump device is an alternative approach to exciting a magnet coil, which can eradicate this parasitic heat load, as such devices do not require direct physical connection to the HTS circuit. However, earlier proposed flux pump designs have required power-dissipating active components to be located within the cryogenic envelope, thus imposing their own parasitic heat load. Here, we report the successful demonstration of a mechanically rotating HTS flux pump, which operates entirely outside of the cryogenic envelope. This prototype device projects flux across a cryostat wall, leading to the injection of a direct current into a thermally isolated closed HTS circuit. This is achieved through the implementation of a flux-concentrating magnetic circuit employing ferromagnetic yoke pieces, which enables flux penetration of the HTS circuit at large flux gaps. We have demonstrated the injection of direct currents of > 30 A into a closed HTS circuit while operating this device across a cryostat wall.

The transfluxor

Abstract: In a recent paper the authors have announced a novel device showing that completely new switching and storing functions can be performed by employing magnetic cores with two or more apertures, (Magnetic circuits using multiaperature cores have also been reported elsewhere.) instead of the conventional single-aperture cores, thereby creating a number of distinct flux paths via the legs of the core. The new device operates by the controlled transfer of flux from leg to leg in the magnetic circuit and was consequently named "transfluxor."