JPH0477543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotating electrical machine with a commutator, and particularly to one in which a commutating state can be detected.

[Background of the invention]

In general, the lifespan of DC and AC commutator machines that have a commutator and brushes is determined by the quality of their rectification performance.
In particular, if the deterioration of commutation is significant, a flashover phenomenon will occur, damaging the area around the commutator and making it impossible to operate. For this reason, it is important to accurately detect the rectification state, and various methods have been proposed for a long time.
Each has its advantages and disadvantages.

For example, there is a method of installing an antenna near the brush to detect electromagnetic waves caused by sparks, but this makes it impossible to distinguish between sparks caused by over-rectification caused by too much rectification compensation and sparks caused by insufficient rectification caused by insufficient rectification compensation. However, there are drawbacks such as the ease with which external noise enters.

There is also a method of optically detecting sparks from brushes, but it is also difficult to distinguish between sparks caused by over-rectification and sparks caused by under-rectification, and it is difficult to detect sparks from all brushes. There are disadvantages such as being

Furthermore, there is a method for detecting the voltage between armature terminals,
There is also a method of detecting the brush contact voltage drop by installing a detection brush next to the main brush, but these methods have the disadvantage that if the seating of the brush itself deteriorates, noise will enter the detection voltage, impairing reliability. Since the detection is performed directly from the main circuit, there is a drawback that insulation processing is difficult when extracting the signal from the detection section.

In addition, in an AC commutator machine, since the power source is AC, there is a method of observing the voltage between the terminals of the field winding using a cathode ray tube oscilloscope in order to distinguish between sparks generated by the transformer electromotive force and reactance voltage. (Hitachi Review Vol. 38, No. 9, pp. 75-85). The outline is shown in Figure 1. AC commutator 1, armature 2, brushes 3a, 3b, commutator winding 4 for rectification compensation
(or a compensation winding), and a field winding 5 are connected in series, and power is supplied from an AC power source 6. A load 7 is connected to the armature 2, and a field winding 5
A cathode ray tube oscilloscope 8 for observing the voltage waveform between the terminals is connected to both ends of the terminal.

Now, when AC voltage is applied from the power supply 6, the AC current flows through the armature 2, the commutator winding 4, and the field winding 5, and the main magnetic flux alternates, so between the terminals of the field winding 5. An alternating current voltage is generated, and a waveform as shown in FIG. 2, for example, is obtained on the oscilloscope 8. Normally, among the windings constituting the armature 2, the winding short-circuited by the brushes 3a or 3b, that is, the rectifier coil, generates a reactance voltage due to the transformer electromotive force due to the alternation of the main magnetic flux and the rectification phenomenon, resulting in a short-circuit current. flows, brush 3
When switching between a, 3b and a commutator bar (not shown), the short circuit current is suddenly interrupted, resulting in a spark. At this time, since a spike-like induced voltage is superimposed on the voltage waveform at both ends of the field winding 5, the rectification state is determined by observing this voltage waveform. In FIG. 2, the spike-like induced voltage in section a is due to reactance voltage deficiency compensation, and that in section b is due to transformer electromotive force. In addition, in the case of reactance voltage overcompensation, the spike-like induced voltage at part a appears in the opposite direction. However, although it is possible to observe the voltage waveform with this method, the voltage induced by the spark is very small compared to the field winding terminal voltage, making it difficult to quantitatively understand the rectification state. There are drawbacks such as the difficulty of insulating the signal from the main circuit in order to extract it as a signal.

It is also conceivable to apply the method shown in FIG. 1 to a series motor whose power source is a pulsating DC power source or a pure DC power source. This is because it is possible to determine whether a spark is due to over-rectification or under-rectification from the direction of the spike-like induced voltage superimposed on the field winding terminal voltage. However, it is clear that this method also has the same drawbacks as above, and especially in series motors that perform weak opening operation, the field winding terminals are short-circuited by a shunt resistor, so spark-induced There is a problem in that the voltage is extremely reduced and it is difficult to detect the induced voltage caused by the spark.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to accurately detect not only the magnitude of sparks but also whether they are over-rectified or under-rectified by using a circuit that is electrically separated from the armature circuit and the field circuit. An object of the present invention is to provide a rotating electric machine with a commutator that can be detected.

[Summary of the invention]

In order to achieve the above object, the present invention includes a stator having a main pole and a counter pole on the inner periphery of a yoke, a rotor having an armature winding and a commutator, and a brush that is in sliding contact with the commutator. In rotating electric machines with commutators,
It is characterized in that search coils having the same number of turns are wound around at least two adjacent main poles, and the adjacent search coils are connected with different polarities.

First, the principle of the present invention will be explained.

FIG. 3 is a partial sectional view of the DC machine. In this figure, 9 is a yoke, 10 is a main pole core, 11 is a field winding, 12 is a commutator core, and 13 is a commutator winding, which constitute a fixed member. Further, 14 is a slotted armature core, 15 is an armature winding, and 16 is a commutator, which constitute a rotor. 17 is commutator 1
This is a brush that slides into contact with 6. The armature winding 15 is connected to a commutator 16 and is supplied with electric power from a brush 17.

Rectification means that the armature winding, that is, the rectifier coil 15a short-circuited by the brush 17, is connected to the adjacent main pole iron core 10.
This is a phenomenon in which the direction of current in the rectifier coil 15a is reversed while passing through the middle of the rectifier coil 15a. That is, as shown in FIG. 4, the current in the rectifier coil is reversed from +Ia to -Ia (or vice versa) within the rectification period T _C. At this time, due to the inductance L of the rectifier coil, a reactance voltage of e _r −Ld _i /d _t (1) is generated in the rectifier coil. On the other hand, when an armature current is passed through the commutator winding 13 and a commutator magnetic flux is generated by the magnetomotive force, a rectifier electromotive force (e _c =VBl) is induced in the rectifier coil. Good rectification can be obtained by canceling the reactance voltage e _r with this rectified electromotive force e _c .

In good commutation, the current in the commutator coil varies linearly as shown in FIG. 4a. Commutation deteriorates when the current in the rectifier coil changes as b or c. b is the reactance voltage e _r
If the relationship between e _c and rectified electromotive force e c is e _r ≪ e _c , c is e _r ≫
This is the case for e _c .

By the way, when the rectification curve is as shown in Figures 4b and 4c, due to the magnetomotive force caused by the short-circuit current flowing in the rectifier coil, the magnetic flux Δφc that increases or decreases the main magnetic flux _φn due to the main pole winding 11 increases or decreases, as shown in Figure 5. arise. That is,
In linear rectification (Fig. 4a), as shown in Fig. 5b,
While the short-circuit rectification of the rectifier coil 15a becomes zero at the center of the rectification period, in the case of over-rectification (b), the direction of the current in the rectifier coil 15a quickly reverses as shown in Fig. 5C. At the center of the rectification period, a current in the direction shown flows through the rectification coil 15a, and a magnetic flux Δφc in the opposite direction to the main magnetic flux Ф _n is generated. In addition, in under-rectification (c), as shown in Fig. 5D, the direction of the current in the rectifier coil 15a is slow to reverse, so the current in the direction shown flows through the rectifier coil 15a at the center of the rectification period, and the main magnetic flux A magnetic flux Δφc in the same direction as Φ _n is generated.

In this way, during over-rectification and under-rectification, the above-mentioned phenomenon is repeated for each commutator segment, so
By detecting the change in magnetic flux Δφc due to this, the rectification state can be indirectly detected.

[Embodiments of the invention]

FIG. 6A shows an embodiment of the present invention. In FIG. 6A, the same parts as in FIG. 3 are given the same reference numerals. In this embodiment, the magnetic flux Δφc generated in each main pole iron core 10 by the short-circuit current of the rectifier coil 15a is
A search coil 18 is wound around the sensor to detect changes in . These search coils 18 are connected so that the direction of magnetomotive force is opposite between adjacent main poles, as shown in FIG. 6B.

FIG. 7 shows the winding position of the search coil 18, where A shows the case where it is provided at the tip of the main pole iron core 10, and B shows the case where it is provided at the base of the main pole iron core 10. As long as the magnitude of the change in the magnetic flux Δφc is sufficient, the search coil may be partially provided on the main pole surface.

FIG. 8 shows an example of a voltage waveform generated at the terminal of the search coil shown in FIG. That is, in the same slot, the number of coil sides of each upper and lower layer conductor is 3.
In a commutating state where sparks are generated from each commutator segment, sparks occur at intervals of the commutator period T _S , and the direction of the voltage induced in the search coil will suppress changes in the magnetic flux Δφc. The output voltage e _s of the search coil, where n is the number of turns of the search coil at each pole, can be expressed as e _s =−n·Δφc/dt (2).

Assuming that the output voltage of the search coil in FIG. 8A is generated in an under-rectified state, the output voltage of the search coil in an over-rectified state becomes as shown in FIG. 8B. Therefore, the polarity of the output voltage of the search coil indicates whether it is over-rectified or under-rectified, and its magnitude indicates the strength of the spark.

FIG. 9 shows an example of a circuit for processing the output voltage e _s of the search coil 18 shown in FIG. The pulsed output voltage e _s of the search coil 18 is first amplified by the amplifier 19 and input to the peak value hold circuit 20 . The peak value hold circuit 20 consists of a pair of circuits corresponding to positive and negative input voltages, and when the input voltage is positive, the peak values are connected and the DC voltage e _p as shown in FIG. In this case, it outputs a DC voltage -e _p as shown in Figure A. This output is input to the voltage correction circuit 21. The voltage correction circuit 21 corrects the input voltage to a voltage proportional to the spark number. For example, if the relationship between the input voltage and the number of sparks is as shown by the broken line b in FIG.
Correct it so that it becomes and output it. Voltage correction circuit 2
Depending on the purpose of use, the output of No. 1 may be input to the rectification status monitoring device 22 to monitor the rectification status on the screen, or input to the comparison circuit 23 to monitor the rectification status if the value exceeds a certain set value. In this case, the alarm circuit 24 can be activated.

FIG. 12 shows another embodiment of the invention. In this embodiment, search coils 18 are wound around two adjacent main poles, and the two search coils have the same number of turns and opposite winding directions. If there is a phase difference of 180° in the permeance change in the main pole lower gap between adjacent main poles, with this configuration, the change in permeance in the main pole lower gap can be canceled out by the two search coils. Therefore, search coil 1
Only the induced voltage due to the change in magnetic flux Δφc caused by the short-circuit current of the rectifying coil can be obtained at both terminals of the rectifying coil. Therefore, the circuit for processing the output of the search coil 18 may be the same as that shown in FIG. As is clear from this example, the minimum unit for eliminating the influence of the permeance of the gap under the main pole is two search coils wound around adjacent main poles.

In the above embodiments, the case of a DC machine has been described, but the present invention can be similarly applied to an AC commutator machine and the like.

〔Effect of the invention〕

As explained above, according to the present invention, the change in magnetic flux caused by the current flowing through the rectifier coil is directly detected by the search coil wound around the main pole, thereby determining the size of sparks and whether or not there is over-rectification or insufficient rectification. Rectification can be easily and accurately detected.

Moreover, the search coils are connected to at least two adjacent search coils.
Since the two main poles are wound with the same number of turns, and the adjacent ones are connected with different polarities, changes in permeance in the air below the main pole can be canceled out by the two search coils, and as a result, filters, etc. It is possible to obtain only the signal due to the magnetic flux generated by the current flowing through the rectifying coil without using the rectifying coil. Furthermore, since the search coil is electrically separated from the armature circuit and the field circuit, there are advantages in that detection signals can be easily processed and reliability is improved. The signal obtained by the search coil can be used to monitor the rectification status, generate an alarm when a rectification abnormality occurs,
It can be used as a feedback signal for driving a protection device and controlling rectified magnetic flux using a commutating pole or the like.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a spark determination method in a conventional AC commutator machine, Fig. 2 is a graph showing an example of field winding terminal voltage in the same circuit, and Fig. 3 explains the principle of the present invention. Fig. 4 is a graph showing the rectification curve, Fig. 5 A is a partial exploded view of the DC machine, B, C, and D are linear rectification, over-rectification, and under-rectification conditions, respectively. FIG. 6A is a developed view showing a DC machine according to an embodiment of the present invention, FIG. 6B is a developed view showing the connection state of the search coil, and FIGS. Figure 8 A and B are waveform diagrams of the induced voltage of the search coil, respectively.
The figure is a block diagram of the search coil induced voltage processing circuit in Figure 6, Figures 10A and 10B are output waveform diagrams of the peak value hold circuit in the same circuit, and Figure 11 is the input of the voltage correction circuit in the same circuit. A graph showing the relationship between outputs and FIG. 12 are block diagrams showing another embodiment of the present invention. 9...Yoke, 10...Main pole core, 11...Field winding, 12...Commuting pole core, 13...Commuting pole winding, 1
4... Armature core, 15... Armature winding, 16...
...Commutator, 17, 17a, 17b...Brush, 1
8...Search coil.

Claims (1)

[Claims] 1 In a stator having a main pole and a counter pole on the inner periphery of the yoke, a rotor having an armature winding and a commutator, and a brush in sliding contact with the commutator, at least two adjacent A rotating electrical machine with a commutator, characterized in that search coils having the same number of turns are wound around the main poles, and adjacent search coils are connected with different polarities.