SU1415050A1 - Variable-induction position pickup - Google Patents

Abstract

The invention relates to a measurement technique and is aimed at increasing the reliability of an inductive rotor position sensor of an electric machine, for example, a valve motor, with respect to the axes of its statorial windings. The position sensor contains a permanent magnet 1 connected to the rotor of the machine, and two closed stationary magnetic cores 2 and 3, in areas with a 20-30% reduced cross section of which the measuring windings 4 and 5 are placed, forming a bridge circuit together with the semi-windings matching transformer 9, the secondary winding of which is connected to the input of a phase-sensitive amplifier, a demodulator 12, which controls the operation of the power transistors 21 and 22. With the passage of a constant magnet 1 past the magnetic cores 2 and 3 alternately they periodically saturate their sections where windings 4 and 5 are located, which leads to the formation of a voltage and phase modulated moduli whose envelope has an increased gradient of rise and fall, which makes the position sensor practically insensitive to oscillations its ac voltage. 3 il. G "

Description

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The invention, E, relates to a measurement technique and makes it possible to determine the angular position of a rotor of an electric machine, such as a valve motor, relative to the axes of its stator windings.

The aim of the invention is to increase the click. the reliability of the operation of the reactive g & t position of the rotor of an electric machine with fluctuations in the amplitude of the supply voltage by increasing the steepness of the rise and fall of the envelope modulated in phase and amplitude of the voltage at its output, which after conversion into different voltage pulses It is used to control two power transistors operating in the opposite phase, and the moment of the phase change on the BO el. the voltage at the output of the coils corresponds to the coincidence of the magnetic axis of the rotor and the axis of the winding

I Fig. -1 shows an electrical inductive sensor; 2, from the positions of the magnet relative to the magnetic conductors of the position sensor in FIG. 3, a voltage diagram of U (t) at its output.

An inductive position sensor rotor of an electric machine with respect to the axes of its stator windings contains a permanent magnet 1 designed for communication with the rotor J. and two closed magnetic cores 2 and 3 installed either on the stator in the plane passing the cutting axis. machine stator, and offset from one another by 180 al. When using one bipolar magnet 1, the magnetic cores 2 and 3 are installed diametrically opposed, as shown in FIG. Measuring windings 4 and 5 interconnected with each other by the beginning and end on one side are located on the sections of the magnetic cores that are more distant in the radial plane relative to the longitudinal axis of rotation of the magnet 1, and the point 6 of their connection is connected to the same AC power supply view. through the decoupling transformer 7, and the opposite, the conclusions of the c6ei-ix windings. 4 and 5 are connected to the primary winding of the matching transformer 8, the outlet from the midpoint of which is connected, to another output of the power source through the specified transformer 7. Thus, the change

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The 4 and 5 sensor windings form the adjacent arms of the bridge circuit, the other two arms of which are formed by the primary windings of the matching transformer 8. The secondary windings 9 and 10. of this transformer are connected to the input of a phase-sensitive amplifier-demodulator P, made on the diode 12 and the transistor 13, which is powered from the winding 4 of the transformer 7 through a rectifying bridge 15 and a smoothing RC filter 16. The load of the 5-ld-demodulator is, for example, blocked by the emitter-diodes 17 and 18 P Passing seeps transistors 19 and 20 operating in antiphase.

The sections of the magnetic cores 2 and 3, on which the measuring windings 4 and 5 are placed, are made with a cross section that is smaller by 20-30% than the rest of these pumping lines, which ensures their periodic saturation with the corresponding position of the magnet 1.

The ipaductive position sensor operates as follows.

When applying voltage 1, from.

0 transformer 8 on the sensor in its measuring windings 4 and 5 currents flow, the instantaneous values of which are determined, ceteris paribus, by the magnetic state of the sections of the magnetic cores 2 and 3, on which they are located. In turn, the magnetic state of these sections of the magnetic cores depends on the magnitude and mutual direction of the fields created by the rotating permanent magnet 1 and the currents flowing through the windings 4 and 5. During the rotation of the permanent magnet 1, the cores 2 and 3 periodically and alternately saturate, whereby a high-frequency signal Y, modulated in phase and amplitude, appears on the winding 9 of a matching transformer 8 (Fig. 2). The frequency of the modulated signal envelope is equal to the frequency of rotation of the rotor.

0 When inverting the phase of the signal U, which occurs at the moment of time when one of the magnetic cores comes out of the nascene and the other is saturated by the action of the rotating field

5 permanent magnet 1, a phase-sensitive amplifier-demodulator 11 provides a change in the polarity of the voltage at the output of the filter 16 and a corresponding change in the direction of the 5

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currents flowing pr input circuit training u to m to p m

In power transistors 19 and 20, the winding 10 of the positive feedback contributes to the rapid re-magnetization of the core of the transformer 9, thereby significantly increasing the steepness of the fronts of the output voltage of the phase-sensitive amplifier-demodulator 11 and virtually eliminating the dead zone with zero signal level located between pulses of different polarity. As a result, there is no need for additional sources of blocking voltages to reliably provide the cut-off mode of the transistors 19 and 20 in the absence of control voltage at their inputs.

Due to the fulfillment of sections of magnetic lines 2 and 3, occupied by windings, with a smaller section of 20-30%, than the section of their sections that are closer to magnet 1, the steepness of the fronts of the voltage envelope Uy becomes much larger

than with the other (fig.Z). This ensures the stabilization of the parameters of the positive half-periods of the doubled frequency voltage (the field of positive-2Q voltages Well, lying inside, the rhombus in Fig. 3) when changing

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Licensed voltage limits.

This effect is due to the fact that the magnetic fluxes of magnetization and excitation in some areas of each magnetic core coincide in direction, while in others they are directed oppositely. When the polarity of the voltage Uf is changed, the places of the consonant (counter) effect of the magnetic fluxes move to the opposite parts of the sensor magnetic cores.

Obviously, those of the magnetic cores, in which the excitation and biasing currents coincide in direction, are fastened more quickly. After saturation of such a section, the rate of current increase in the measuring winding of the sensor is determined by the residual inductance of the winding in the saturated state of the corresponding magnetic circuit. In case of unequal cross-section of the sections of the magnetic cores, the sensor has the property of changing the value of the residual inductance when different sections of its magnetic cores are saturated.

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Thus, for example, the residual potential of winding A (5) when the portion of the magnetic conductor occupied by the winding is located is much less than the residual inductance of the same winding upon saturation of the portion of the magnetic circuit located closer to the axis of rotation of the magnet 1.

This is due to the fact that in the first case the saturated part of the core is not covered by the measuring winding, and the residual inductance value of this winding is mainly determined by the cross section of the saturated section and the relative magnetic permeability of the saturated section, while in the second case it is determined by the relative magnetic permeability of an open unsaturated core covered by a winding, since the saturated region adjacent to magnet 1 can be replaced by an equivalent air gap

Distinction is indivisibility saturated.

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windings into different half-currents of the sensor supply voltage causes, at these time intervals, an unequal current rise rate in the measuring winding after saturation of the corresponding section of the magnetic conductor and, therefore, unequal steepness of the output voltage envelope and winding 9 in different half-periods (FIG. 3) .

In order to provide greater efficiency of the amplifier DDP demodulator, it is necessary to wind the .9 transformer 8 so that it is connected to the input of the transistor 13 so that it saturates in those half-periods of the voltage Uy, at which its envelope has a large slope (positive voltage half-periods UY on the oscillogram (Fig. 3). Since at these times the steepness of the change in the envelope voltage Uy is much greater than in the negative period, the operating conditions of the transistor 13 of the demodulator 11 will be of little critical to the change in the sensor supply

voltage and „wide limits

Claims (1)

occurring during the operation of the sensor. This ensures the high quality of the sensor output signals and its high reliability under the conditions of supply voltage instability. Invention Formula An inductive rotor position sensor of an electric machine, comprising a permanent magnet designed to communicate with the rotor, two fixed-mix on the stator closed magnetic conductor, installed with displacement relative to the other to el.grad, measuring windings located in the sections of the magnetic conductor radially more distant from P { the odol axis of rotation of the magnet than its other sections, the beginning of one measuring winding is connected to the end of the other and their connection point n; It is simply assigned to be connected to the single-terminal of a source of power for an alternating current, matching the transformer, to the primary winding of which opposite terminals are connected. both measuring windings, and the removal from the midpoint is intended to be connected to another view of the power source, and a phase-sensitive amplifier-demodulator, to the input of which the secondary winding of the matching transformer is connected, in order to increase the reliability the sensor by increasing the steepness of the rise and fall of the envelope of the phase and amplitude modulated voltage at its output, the sections of the magnetic conductors on which the measuring windings are placed are filled with a 20–30% smaller section than the remaining sections of these magnetic circuits. 2f "