Sang-Sub Jeong

Design and analysis of high speed slotless PM machine with Halbach array

Slotless machines have been applied for a very high rotational speed and/or the ripple-free torque. In this paper, slotless machines equipped with external 4-pole field Halbach and radially magnetized PM array for electro-mechanical battery. This paper describes the comparison of the design guidelines, magnetic field characteristics, required magnet volume and optimal thickness of windings for two types of PM rotors.

The characteristics analysis of eddy current brake system using the linear Halbach array

Summary form only given. The eddy current brake system ofa high-speed railway has been developed because of the mechanical adhesion limit. It have been used in magnetic levitation applications and in high velocity trains in order to avoid the abrasion of a mechanical disc brake. The eddy current brake system with permanent magnet has a simple structure, rugged characteristics and low cost because of no control and power system. In this paper, the characteristics analysis of an eddy current brake system using the linear Halbach array are analyzed by the analytical method and FEM.

Comparison of three types of PM brushless machines for an electro-mechanical battery

The paper reports on the comparison of three types of permanent magnet machines as the motor/generator for an electromechanical battery. To apply to high-speed drives, slotted, slotless ring-wound and coreless Halbach machines are designed to have the same capability and limited size. Three types are also compared with respect to their topology, size, magnetic field, inductance, torque and generating voltage, loss, and efficiency.

The application of linear Halbach array to eddy current rail brake system

This paper proposes two kinds of eddy current brakes with permanent magnet, One consists of hexahedron shape of a segmented permanent magnet and iron core (et seq. iron core-PM array). The other is composed of only a segmented permanent magnet (et seq. Halbach array). We use a finite element method to compute the magneto static field. Also, we use the Galerkin-FEM with linear interpolation function may oscillate between the adjacent nodes to calculate the braking and attraction force. The advantages of the Halbach array compared with the iron core-PM array are discussed.

Electromagnetic analysis and control parameter estimation of moving-coil linear oscillatory actuator

This paper deals with an electromagnetic analysis and control parameter estimation of a moving-coil linear oscillatory actuator (MCLOA). Analytical solutions for electromagnetic characteristics of the MCLOA are obtained from transfer relations derived in terms of a magnetic vector potential and two-dimensional (2D) rectangular coordinate systems. And then, on the basis of 2D analytical solutions, control parameters such as the thrust constant, the back-emf constant, and winding inductances are estimated. Finally, analytical results for both electromagnetic characteristics and control parameters of the MCLOA are validated extensively by finite element analyses. In particular, test results such as static thrust, resistance, and inductance measurements are given to confirm the analyses.

Armature reaction effect and inductance of moving coil linear oscillatory actuator with unbalanced magnetic circuit

The unbalanced reciprocating force due to armature reaction field decreases the advantage of moving coil LOA, such as a high degree of linearity and controllability in the force and motion control. This paper firstly describes the coil inductance, the deviation of flux density, and the unbalanced reciprocation force, which are derived from the permeance model of motor. Secondly, the analytical method is verified using 2D finite element method and tests. Finally, the dynamic simulation algorithm considering the armature reaction and variable inductance is proposed and confirmed through the experiments.

Design, analysis, and manufacture of large linear motor damper for structural vibration control system

Summary form only given as follows. sWith the introduction of high-energy product rare-earth cobalt magnets and especially NdFeB permanent magnets (PMs), the moving coil linear oscillatory actuator with the high power are being developed. However, the manufacture of a large PM linear actuator is difficult because of the limit of PM size and the attraction and repulsion at the assembly of PM. This paper deals with the design, analysis and manufacture of the linear motor damper (LMD) with the high power for the structural vibration control. LMD consists of the NdFeB magnets, a coil-wrapped nonmagnetic hollow rectangular structure, an iron core as a pathway for magnetic flux, and mechanical spring. The PM field part composed of magnet modules and iron yoke, is moving mass itself, 1500 kg. LMD therefore has a simplified structure and requires a few elements in the driving system, being compared with a rotary motor damper and a hydraulic damper. The control parameters and the frequency response were extracted from the dynamic experiments. Performance tests of vibration control system were carried out on the test structure of about 120 tons subjected to sinusoidal or random base excitation. From these tests, it was confirmed that the acceleration level of the structure was drastically reduced near the resonant region.

Armature field analysis and position/stroke control of moving coil linear motor for springless propulsion and reciprocation

The unbalanced reciprocation force due to armature reaction field decreases the advantage of the moving coil linear motor, such as a high degree of linearity and controllability in the force and motion control. This paper first describes the coil inductance, the deviation of flux density, and the unbalanced force, which are derived from the permeance model of the motor. Secondly, the dynamic simulation algorithm considering the armature reaction effect and variable inductance is proposed. Thirdly, the control algorithm is proposed to reciprocate a load without mechanical spring at the required stroke and position. Finally, the validity of the proposed algorithm is confirmed by experiments.

Reduction of armature reaction and inductance in the moving coil linear actuator for a high performance drive

Summary form only given. In a moving coil linear actuator, the armature field shifts and distorts the airgap flux density distribution due to the magnet alone by a certain amount, which causes the unbalanced reciprocating force. In this paper, we propose a reduction method for the armature reaction and coil inductance to decrease the unbalanced force and shorten the access time. The proposed model has a shorted ring, a saturated core, differential winding, and a Halbach array. The shorted ring consists of a conductive layer material and aids the coil current in changing state rapidly. Moreover, a magnetically saturated core is used in order to suppress the increase of the moving coil inductance. The MMF of each coil of the differential winding are opposite. The coil inductance of the Halbach array model is much lower because of the magnetic circuit with an air-core. A general model and four types are compared with respect to their topology, size, inductance, force constant, and response time. The comparison of force constant according to coil current is shown.