Effect of Rotor Misalignment on Magnetoelectric Valve Motor Performance

Abstract

A mathematical model of the magnetic field in the working clearance of a magnetoelectric valve motor is presented when the rotor is misaligned relative to the stator axis, which occurs during manufacture, for example, due to defects in bearing panels or during operation due to bearing wear. Using the conformal transformation of an uneven air gap into a uniform (circular ring), a study of the magnetic field in the air gap of the engine was carried out. A case is considered when the section of the air gap with the minimum size is stationary and is associated with a specific place on the surface of the stator boring. The serrature of the stator was taken into account on average using the Carter coefficient. The magnetic field in the inhomogeneous air gap created by the rotor magnets and the current of the stator winding was assumed to be plane-parallel, having a two-dimensional character.
 
 It is obtained that the misalignment of the rotor associated with the rotational motion of the air gap section with a minimum size leads to the appearance of non-sinusoidal EMF and pulsations of electromagnetic moment with a frequency exceeding 3p times the rotational speed of the rotor (p is the number of pairs of poles). With fixed eccentricity, an alternating EMF is induced along the rotor shaft, causing alternating current in the circuit: shaft – bearings – bearing panels – stator housing.
 
 Pulsations of the moment of the electromagnetic moment of the engine are caused by the appearance of mainly the 3rd and 9th harmonics, the values of which increase with increasing misalignment according to a law close to linear. The constant component of the electromagnetic moment increases somewhat with increasing misalignment.