JPS6166587A - Rectification compensator of dc machine - Google Patents

Abstract

PURPOSE:To prevent brushes from abnormally wearing or a commutator from roughly damaging by turning off a semiconductor element when an armature current abruptly decreases and discharging the induced voltage of an auxiliary winding to a capacitor. CONSTITUTION:A comparator 27 outputs a signal to a gate signal generator 16 when an armature current abruptly decreases to a limit or lower while an armature is rotating. The generator 16 receives it to turn off GTOs 22A, 22B. As a result, an auxiliary winding 10 induces a voltage upon the variation of a magnetic flux when the armature current abruptly decreases, but since it forms a closed circuit through a capacitor 25 and F.D 23B, 23C, only a small current flows. Accordingly, sparks from brushes can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a DC machine, and more particularly to a rectification compensation device for a DC machine that can improve the rectification effect.

[Background of the invention]

It is no exaggeration to say that the quality of rectification performance of a DC machine determines the performance and life of the machine, and much research has been carried out in the past. The quality of this rectification performance is determined by measuring the no-spark zone of the actual machine. On the other hand, DC machines have a phenomenon in which the position of the sparkless band moves depending on the rotation speed, and if the amount of movement of the sparkless band is large, it becomes impossible to operate with sparkless commutation.

The main circuit configuration of the chopper type current control circuit is shown in FIG. In the figure, when the GTO thyristor (hereinafter simply referred to as GTO) 22A is turned on, the auxiliary winding 10 is connected to the DC power supply 1.
A current ipl is supplied from 7, and when turned off, a current ipz flows through the flywheel diode 23B due to the energy of the inductance. 23A is an FD for GTO22A, and 24 is a snubber circuit. Here, the problem is that the auxiliary winding 10 is always
23B forms a closed circuit and is placed in the same magnetic path as the commutator winding as shown in Figure 3, it was found that the following drawbacks occurred. .

In other words, in a DC machine where starting and stopping are frequently repeated, the armature current rises and falls transiently, and the armature current also flows through the commutator winding 8, so the commutator magnetic flux also changes transiently. do. Therefore, the auxiliary winding 10 induces a voltage accompanying the change in magnetic flux. During startup and steady operation mode, current control circuit 1
8 operates, and the required current ip flows through the auxiliary winding 10.

However, in the stop mode, the armature current decreases transiently, so the command value becomes smaller than the current current supply amount command, so the GTO 22A turns off. Since the auxiliary winding 10 induces a voltage accompanying the change in magnetic flux, this induced voltage causes the current ip2 to continue through the F-D 23B. As a result, the rectifier coil, which is short-circuited by the brushes of the armature rotating due to inertia, induces a voltage by the magnetic flux from the auxiliary winding 10, and a short-circuit current flows through the brushes 11. In particular, it has been found that when the reduction rate of one armature current is large and the rotational speed is high, a large short-circuit current flows, generating large sparks from the brushes, causing abnormal wear of the brushes and damage to the commutator.

As a countermeasure against this problem, there has been proposed the rectification compensation system shown in FIGS. 3 to 6 in Japanese Utility Model Application No. 50-99408. FIG. 3 is an exploded view of the main parts of the DC machine, in which a main pole 2 and a complementary pole 3 are provided on the inner peripheral side of the yoke 1. The main pole 2 is formed by a main pole iron core 4 and a main pole winding 5, and serves to provide main magnetic flux to the armature winding 6 of an armature 9 rotating inside the stator. It is formed by an iron core 7 and a commutator winding 8, and provides a commutator magnetic flux for generating a rectified electromotive force during a rectification phenomenon in which the current flowing in the armature winding 6 is reversed.

In addition, as shown in FIG. 4, the auxiliary winding 10 provided at the tip end of the commutator core 7 moves its spark-free band position to the over-rectifying side (excessive commutator flux) as the rotational speed increases. Therefore, the auxiliary winding magnetomotive force is adjusted in the direction of decreasing the interpole magnetic flux, and the load shaft is moved to the 0-P line at the center of the non-sparking zone.

FIG. 5 shows an embodiment in which the amount of current in the auxiliary winding is controlled according to the rotational speed and the armature current, and is a block diagram of a circuit configuration for compensating for the no-spark band movement phenomenon.

In FIG. 5, armature current IM flows to commutator winding 8 via brush 11 and commutator 12. On the other hand, the current ip of the auxiliary winding 10 is obtained by inputting the outputs of the current detector 13 and the rotation speed detector 14 to a multiplier 15, and inputting the output of the multiplier 15 to a gate signal generator 16, which generates a gate signal. The DC current from the external DC power source 17 is supplied by controlling the switching frequency 11 of the semiconductor elements (GTO thyristor, power transistor, etc.) in the current control circuit 18, and the DC current from the external DC power supply 17. ing.

From this, when the current ip of the auxiliary winding 10 increases according to the rotation speed and the magnitude of the armature current, the interpolation magnetomotive force changes,
As shown in FIG. 4, the load axis moves onto the 0-P line at the center of the no-spark zone. As a result, the DC machine can be operated with sparkless rectification.

However, when the above-mentioned rectification compensation method is applied to a DC machine that is frequently started and stopped, it has the disadvantage that large sparks are generated from the brushes, causing abnormal wear of the brushes and, eventually, damage to the commutator.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rectification compensation device for a DC machine that does not generate sparks and can perform good rectification compensation no matter what kind of machine it is applied to.

[Summary of the invention]

Sparks generated from the brush only occur when in stop mode,
In particular, paying attention to the fact that the armature current increases when it suddenly decreases, the present invention turns off the semiconductor element when the armature current suddenly decreases, and discharges the induced voltage in the auxiliary winding into the capacitor.

[Embodiments of the invention]

FIG. 1 shows the main circuit configuration of the current control circuit of the present invention (however, the snubber circuit is omitted). In Figure 1, GTO22B and F-D23D are newly inserted into the main circuit,
The F-D 23C operates in the stop mode and a capacitor 25 is provided on the power supply side. The auxiliary winding 10 is GTO
When 22B is turned on and GT022A is turned on, current ipI is supplied from the DC power supply 17, and when GTO22A is turned off, the energy of the inductance is used to
A current ipz flows through 22I)-F-D23B.

Here, GTO22A in stop mode.

When both 22B are turned off, F-D23C-capacitor 2
Current jps flows through 5-F-D23B. This current ips becomes a small current because it is an LRC circuit.

FIG. 2 shows an embodiment of the circuit block of the rectification compensator of the present invention. 26 is a differentiation circuit, 27 is a comparison circuit, and 28 is a rotation determination circuit. The armature current IAI and the current ip of the auxiliary winding 10 flow in the same manner as in the conventional case. On the other hand, when the armature current suddenly decreases, the output from the current detector 13 is input to the differentiating circuit 26, and the negative output of the differentiating circuit 26 (which becomes negative when the armature current suddenly decreases) is The comparison circuit 27 compares whether the value exceeds a certain value, the rotation determination circuit 28 determines whether the armature is rotating, and the output is input to the comparison circuit 27. 27 is % while the armature is rotating,
When the Isomiko current suddenly decreases beyond a certain limit, a signal is output to the gate signal generator 16.

Upon receiving this signal, the gate signal generator 16 outputs the GTO 22A.
, 22B is turned off. As a result, the auxiliary winding 10 induces a voltage accompanying the magnetic flux change when the πL armature current suddenly decreases, but the capacitor 25 and the F-D 23B.

Since a closed circuit is formed through 23C, only a small current flows. Therefore, the rectifier coil does not generate a large voltage due to the magnetic flux generated by the auxiliary winding, and no large short-circuit current flows, as in the conventional case, so that sparks from the brush can be eliminated.

Although the differentiating circuit was used to determine whether or not the armature current suddenly decreased, the present invention is not particularly limited, and a signal for entering the stop mode of the DC machine main circuit may also be used.

〔Effect of the invention〕

According to the present invention, the brushes will not wear abnormally and the commutator will not be damaged.

[Brief explanation of the drawing]

Fig. 1 is a main circuit configuration diagram of the rectification compensation device of the present invention, Fig. 2 is a circuit block diagram of Fig. 1, Fig. 3 is an exploded view of the main parts of a DC machine, and Fig. 4 is a non-sparking factor with respect to rotation speed. It is. 10... Auxiliary winding, 17... DC power supply, 18...
Current control circuit, 22...GTO thyristor, 23...
・Diode, 25... Capacitor.

Claims (1)

[Scope of Claims] 1. A main pole consisting of a main pole iron core and a main pole winding, and a commutating pole consisting of a commutating pole iron core, a commuting pole winding, and an auxiliary winding, on the inner peripheral side of the annular yoke. a DC machine having a stator with brushes and a rotor equipped with an armature and a commutator; In the rectification compensation device for a DC machine, when the armature current of the armature suddenly decreases, all semiconductor elements in the current control circuit are turned off to form a closed circuit with the auxiliary winding via a diode and a capacitor. A rectification compensator for a DC machine featuring: