SU1677796A1 - Device for studying switching phenomena in electrical commutator machines - Google Patents

Abstract

To study the commutation of collector electric machines, a non-contact induction sensor is mounted above the collector plate between the cock of the collector and the nearby brush. The width of the sensor does not exceed the width of the collector plate. The sensor is oriented along the longitudinal axis of the machine. The invention makes it possible to improve the measurement accuracy of switching parameters. 2 Il.

Description

The invention relates to electrical engineering, in particular, to devices for studying the energy parameters of switching commutator electric machines.

The aim of the invention is to improve the accuracy of measuring the magnitude proportional to the rupture current of the winding core section, when studying the energy parameters of switching by reducing the influence of the air gap oscillations between the induction sensor and the conductor of any section on the measurement result, as well as reducing the electromagnetic fields of the adjacent sections.

FIG. Figure 1 shows the structural diagram for the study of switching and the installation of sensors on the collector of the electrical machine; in fig. 2 - oscillograms of voltage proportional to the section current at the final

the switching stage (curve A), measured from a shunt sunk into the section, and a voltage proportional to the derivative of the rupture current of the same section, measured using the proposed device (curve B).

A device for studying the commutator switching of an electrical machine, for example, of the type PO-550AF, having a collector plate width of 4 mm, contains a non-contact inductive sensor 1, a measuring unit (oscilloscope) 2, a synchronization device 3 and a synchronization sensor 4.

The non-contact inductive break current sensor 1 is a U-shaped open magnetic circuit, for example, 400PN type ferrite with the following dimensions: length 15 mm, width 4 mm, thickness 2 mm. Two wound on the magnetic circuit

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series-connected windings with a wire whose diameter is 0.08 mm. Winding with the number of turns V7 20 are located on opposite sides of the U-shaped mlnitprovod. The magnetic circuit with the windings is enclosed in a permallo magnetic screen. On the side of the open part of the magnetic conductor there is no screen.

A C8-13 electron oscilloscope can be used as a measurement setup.

The synchronization device includes a preamplifier and a driver from the sensor 4.

Synchronization sensor 4 is made in the form of an optocoupler, where the emitter is the AL-107A infrared emitting diode and the ID-3 photodiode is used as a receiver. The emitter and receiver are located on the holder at an angle of 45 to one another and are directed to the free part of the collector (to the free part of the shaft) of the electric machine. There is a label with a reflectivity that is higher than the collector copper. The label is located on the collector plate (on the shaft of the electric machine) and is oriented so that the oscilloscope scan starts at the moment of time preceding the brush to detach from the collector plate, i.e. completion of switching of the section under study.

Induction sensor 1 is installed between the cock of the collector and the nearby brush 5 at a distance of 5 mm from the cock. The sensor is located at the edge of the brush, oriented along the longitudinal axis of the machine outside the brush body, i.e. outside the space bounded by the width of the brush body. It is located above in contact with the brush by the escaping (or incident) plate. Sensor 1 is installed at a distance of 1 mm above the incident (incident) collector plate 6. The distance from the collector 1 mm is determined depending on the maximum value of the differential collector plates, taking into account the collector eccentricity, i.e. depending on the normalized value, for the PO-550 AF engine is 50 μm. Thus, the fluctuation of the distance between the sensor 1 and the collector 6 does not exceed 5%.

The measuring winding of the sensor is connected to the input of an electronic oscillo

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Graph 2. The synchronization sensor 4 is located above the collector (shaft) of the electric machine. The emitter of the sensor 4 is connected to a DC power source, and the receiver of the sensor 4 is connected to the input of the synchronization device 3. The output of the synchronizing device 3 is connected to the external sweep input of the oscilloscope 2.

The device works as follows.

If sparking occurs under the brushes 5 at the moment of detachment of the collector plate 6 from the brushes, a rapidly changing breaking current flows through the switched section 7, the oscillogram of which is shown in Fig. 2 (curve A), in the time interval from t to tЈ.

When an electric machine is sparking in the measuring winding of the sensor 1 installed above the collector plate 6 in which the rupture current flows, an emf is induced proportional to the derivative of the rupture current of section 7. The magnitude and form of the emf are shown in figure 2 (curve B, c

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time interval from t. before induced EMF, proportional to the derivative of the rupture current of the switched section 7, is fed to the input of the measurement setup 2,

Simultaneously from the sensor synchronization 4 through the synchronization device 3 to the input of the external sweep of the measuring setup 2 receives a start pulse.

Therefore, by setting 2 (a voltage pulse proportional to the derivative of the rupture current is observed on the screen), the value is proportional to the derivative of the rupture current flowing through the collector plate of the bits of the section 7 under investigation.

In this way, in each section, the value directly related to the breaking current can be measured in turn.

It should be noted that if the dimensions (width) of the induction sensor 1 exceed the size of the collector plate 6, then in the winding sensor 1 another emf is induced from the current flowing through the adjacent plate located under the brush. EMF is induced by the penetration of the electromagnetic field of the current flowing through the adjacent plate.

Sensor 1 is located at the red line,

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machines above the price of thunder running off or on, running around the collector plate. Installing the sensor 1 with a deviation from the center causes the measurement error to increase, i.e. leads to a decrease in the accuracy of measurements of a quantity proportional to the derivative of the discontinuity current.

As far as the prototype is concerned, the invention, when implemented, ensures the accuracy of measurement of a quantity proportional to the derivative of the rupture current with an accuracy of 10-20%, simplifies the technological process of measuring the rupture current of the electric machines switched with sparking, and also obtain unambiguous values of the parameter proportional to the rupture current which is directly related to the energy characteristics (power or

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Claims (1)

energy of rupture) sparking any section of the winding box. Invention Formula A device for examining switching of a collector electrical machine with a collector of collector plates with cocks and brushes, comprising a non-contact induction sensor mounted above the part of the switched circuit outside the core groove, connected to the measuring installation, characterized in that, in order to improve the measurement accuracy, the sensor is mounted between the cockerel of the collector and the nearby brush over the collector plate in contact with the brush is oriented along the longitudinal axis of the machine and its width does not exceed the width Inu collector plate. 0 Phi2.2