Search

The characteristics of magnet wheels for magnetic levitation and linear drives are investigated by using a three-dimensional computer simulation. Magnet wheels levitate by revolving permanent magnets over a conducting plate, in which the eddy currents are induced. The thrust is also produced by making the torque unbalance. This paper deals with the 'partial overlap type' magnet wheels, producing the lift force and the thrust. The magnetic flux density and eddy currents are examined for the 4-pole and the 2-pole structures.

Lift force, thrust and lateral force characteristics of 'partial overlap type magnet wheel' are presented, where 'magnet wheel' is a proposed electromagnetic device constructed with revolving permanent magnets and conducting plate, and 'partial overlap type' is one type of magnet wheel. Smaller resistivity of conducting plate induces larger lift force and lateral force except thrust. The 2-pole arrangement has maximum thrust at larger overlap than 4-pole. The wall of conducting plate gives larger lateral force without adverse influence on lift force and thrust.

The article discusses boundary element analysis of single-sided linear induction motors (LIM). The end effect of short primary LIM is caused by two factors: the finiteness of primary winding length in the traveling direction of magnetic field; and the finiteness of primary core length. The presence, of the eddy current makes the magnetic flux distribution non-uniform, thus worsening the operating characteristics. The article applies the boundary element method to the analysis of the eddy current distribution inside the secondary conductor with small skin effect. It also analyzes the mechanist of drag force generation at the exit end due to the finiteness of primary core length.

A linear induction motor (LIM) has a much larger mechanical clearance than the conventional rotating-type induction motor and the magnetic path of its primary core is not closed. The effect of stationary pulsating magneto-motive force (mmf) is not taken into account in the analysis based on Fourier transformation, where it is assumed that the primary current is represented by a sinusoidal current of finite length. This assumption holds only when the winding is of single-layer type and the numbers of slots and phases are very large. The pulsating mmf penetrates the secondary conductor and primary core over the full length of the LIM inducing the eddy current in the secondary conductor which increases the secondary copper loss considerably.