Position sensor for armature of step magnetoelectric motor

Details Position sensor for armature of step magnetoelectric motor Position sensor for armature of step magnetoelectric motor

2001-01-24

2002-11-05

Lefkowitz, Edward (Department: 2862)

Electricity: measuring and testing

Magnetic

Displacement

C310S135000

Reexamination Certificate

active

06476601

ABSTRACT:

The invention relates to electrical engineering, and in particular, to devices employed in a step magnetoelectric motor, and it is intended for generating the Sin and Cos of electrical signals that uniquely determine the position of the armature relative to the toothed structure of a motor stator.
There has been known the induction tachometer [
1
] consisting of two U-shaped magnetically soft cores, between which a permanent magnet is located. The magnetically soft cores bear windings. The drawback of this sensor is that its information signals depend both on the position and on the traverse velocity thereof.
There has also been known the device containing a U-shaped magnetic conductor and a permanent magnet, made as a flat rectangular plate placed on the internal side of the magnetic conductor [
2
]. The disadvantage of this device, when used as a position sensor for the armature of a step motor, is the dependence of an information signal both on the velocity and on the position of the armature. All this results in a major error in registration of the position of the armature of a step motor, whereas at motor cutoff the information signal of such a sensor is equal to zero.
The closest to the offered device is the position sensor for the armature of a planar step motor that contains two U-shaped magnetic conductors shunted by a permanent magnet. The magnetic conductors are made of three parts, between which the Hall converters [
3
] are arranged.
The disadvantage of the prototype is the presence of hysteresis of information signals that is due to reversal magnetization of U-shaped magnetic conductors. The reversal magnetization of U-shaped magnetic conductors also causes the dependence the information signal on the motion velocity of the armature, although in a lesser degree than in the prior art devices. The presence of air gaps, in which Hall converters are placed, results in that the information signal amplitude is nearly the order lower than the constant component of the signal. This results in limited thermal stability of the prototype's parameters.
The aim of the invention is to improve the metrological parameters of a position sensor and to provide an opportunity for using the sensor in linear, planar, edge and cylindrical step magnetoelectric motors.
The mentioned aim is achieved by that in the position sensor for the armature (PS) of the step magneto-electric motor containing two composite U-shaped magnetic conductors, on core poles of each magnetic conductor the teeth are formed, which teeth have the difference of group coordinates being equal to (&agr;±0,5) Z; and the position sensor for the armature further contains two magnetic induction converters; in one of the constituent parts of U-shaped magnetic conductors a permanent magnet is connected in series, and the magnetic induction converters are placed, in either mechanical or magnetic proximity, to the pair of like core magnetic poles of a pair of U-shaped magnetic conductors in such a way, that the output signal of converters is in direct proportion to the difference of magnetomotive forces of these magnetic poles.
Here
&agr; is an arbitrary integer and
Z is a teeth arrangement spacing.
The convention of using of a comma for decimal notation is used herein throu such that ½ is represented as 0,5 and ¼ is 0,25.


REFERENCES:
patent: 3836835 (1974-09-01), Sawyer
patent: 4204158 (1980-05-01), Rlcouard et al.
patent: 5754042 (1998-05-01), Schroeder et al.
patent: 2525 (1996-04-01), None
patent: 1432680 (1988-10-01), None

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