JPS5850116B2 - Generating brake device for AC commutator motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic braking device for an AC commutator motor.

For electric motors for power tools such as circular saws, switch O
There is a legal requirement that the brake must stop within 10 seconds after FF, and when the switch is OFF or OFF, the brake system generally uses an electric motor as a generator to convert the rotational energy of the armature into electrical energy. Convert to
Generating brakes, which perform braking action using armature reverse rotation force at that time, are often used.

There are two types of dynamic brakes: a separately excited type in which the field is generated by a separate power source, and a self-excited type that uses residual magnetism when the switch is off.

When the above-mentioned self-exciting type dynamic brake device is used in a DC motor, the problem of thin tubes does not occur in the braking action, but when it is used in an AC commutator motor, power generation does not occur even when the switch is turned off. The brakes may not work.

In other words, since the current is alternating current and draws a sinusoidal waveform as shown in Figure 1, the residual magnetism changes as the current changes, drawing a hysteresis curve, and becomes centered around the zero of the sinusoidal waveform of the current. In the range t, the residual magnetism is low or zero, and in this range t, the switch is set to 0FFL, but because the residual magnetism is low or zero, the motor does not work as a generator and does not function as a dynamic brake. be.

In particular, in conventional AC commutator motors, the field windings at both poles each consist of one winding and are connected in series, so currents of the same phase flow through both field windings, making it difficult to use. The residual magnetism changes at both poles at the same time, and when the residual magnetism of one pole is small when the switch is turned off, the residual magnetism of the other pole is also small, so that a dynamic braking action cannot be performed.

In addition, since it is a matter of course that the field windings of both poles have the same number of turns on each negative winding, even if the field windings are connected in parallel, the impedance is the same and the phase is the same. , a current of 100% was flowing, and similarly to the above, residual magnetism was too small to generate electricity.

As mentioned above, the self-excited dynamic braking device used in conventional AC commutator motors has the disadvantage that the brake does not work every few times, and is very dangerous. The reality is that it is sold as is because the number of times it is used is small.

The present invention is intended to eliminate the above-mentioned conventional drawbacks, and includes an armature having a winding, a field winding having a pair of magnetic poles, and a structure in which the armature and the field winding are normally When operating, connect it in series with the power supply, and
In a dynamic braking device for an AC commutator motor, which is equipped with a changeover switch that is disconnected from a power source and connected to form a dynamic braking circuit when dynamic braking is applied, the bipolar field windings are connected to two windings each having a different number of turns. One winding of the field winding of one pole is connected to the - winding of the field winding of the other pole, and the other winding of the field winding of one pole is connected to the other winding of the field winding of the other pole. The windings of the field windings of the poles are connected in series with each other, and the series-connected windings of one side and the other series-connected windings are connected in parallel with each other, and are in this parallel relationship. By providing a phase difference between the currents flowing in one series-connected winding and the other series-connected winding, even if the residual magnetism from one series-connected winding is small or zero, the other series-connected winding The electric current flowing through the connected windings can generate sufficient residual magnetism to generate electricity, and the electric brake can always be applied even if the switch is set to 0FFL at any point. It is.

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2 showing the circuit diagram, 1 is a power source, Ar is an armature having windings (hereinafter simply referred to as armature) 10 and 20 are corresponding field windings having both NS poles.

The bipolar field windings 10 and 20 are each composed of two windings 101, 102, 201° 202 with different numbers of turns, and one winding 101 in the one-pole field winding 10 and the field of the other pole. The negative winding 201 of the magnetic winding 20 is connected in series, and the other winding 102 of the field winding 10 and the negative winding 202 of the field winding 20 are connected in series, and the one of the above-mentioned series The connected windings 101, 201 and the other series-connected windings 102, 202 are connected in parallel with each other and are arranged at corresponding positions centering on the armature Ar, as shown in FIG. 3, for example.

And one of the series-connected windings 101 in the above-mentioned parallel relationship.
, 201 and the other series-connected windings 102, 202, a phase difference is provided between the currents flowing respectively.

This phase difference is caused by the fact that when the residual magnetism created by the current flowing through the windings 101 and 201 of one series connection is so small or zero that it cannot contribute to the dynamic braking action, the residual magnetism flows to the windings 102 and 202 of the other series connection. It is set so that the residual magnetism created by the current can contribute to the dynamic braking action.

To provide a phase difference, one of the series-connected windings 101.2
The windings 101 are connected in series by connecting a special conductance or capacitor 2 to 01 or by means of a capacitor 2.
．． This is done by making the impedances of windings 201 and the other series-connected windings 102 and 202 different.

Of course, the phase difference may be provided by means of a pond.

Note that the two windings 101 constituting the field winding 10.20
．． 102, 201.202 is a winding 101 in which the number of windings on one side is different from the number on the other side, and the total number of turns as the field winding 10.20 is the same, and one of the windings 101 is connected in series.
, 201 and the other series connected windings 102, 20
For example, two windings are connected so that the total number of turns is the same, for example, one of the two windings is 80 turns and the other is 20 turns, and the winding 101 has 80 turns.
or 202 and winding 201 or 10 with 20 turns
2 in series is suitable for manufacturing purposes such as mounting the windings on the stator core and for reducing magnetic vibration.

Sw is a changeover switch connected to the armature Ar, and this changeover switch +Sw is connected to the terminal 3. which is connected to the one field winding 10. and terminal 4 connected to the other side of power supply 1
When connected to the A side in the figure, the armature Ar and field windings 10, 20 are connected in series to the power supply 1 for normal operation, and the changeover switch Sw
is connected to the terminal 5 provided between the other field winding 20 and the power source 1 and the terminal 6 connected to the field winding 10 via the terminal 3, that is, connected to the B side in the figure. When the motor is turned on, a dynamic braking circuit is configured in which the armature Ar and the field windings 10, 20 are connected to the power source 1 in a disconnected state to perform a dynamic braking action.

R is an external resistance for adjusting the braking time, and is provided to prevent the braking from being too effective and causing recoil when the field winding is 10°200 ohm resistance alone, which could be dangerous when the dynamic braking is applied.

The present invention, as described above, provides corresponding bipolar field windings 10
．． 20 into two windings 101 and 10 with different numbers of turns, respectively.
2, 201, 202, one winding 101 in the field winding 10 of one pole and the other winding 201 of the field winding 20 of the other pole; The other winding 102 and the active winding 202 of the field winding 20 are connected in series, and further the one series-connected winding 101.201 and the other series-connected winding 102.20
2 are connected in parallel with each other, and a phase difference is provided between the currents flowing through each of the series-connected windings 101, 201 on one side and the series-connected windings 102, 202 on the other side in this parallel relationship. , as shown in FIG. 4, with respect to the current a flowing through one series-connected winding 101, 201, a current lags behind the current a flows through the other series-connected winding 102, 202.

Therefore, even if the point in time when the switch is turned OFF is within the range t1 where the residual magnetism created by the current flowing through the windings 101 and 201 of one series connection is small or zero and cannot contribute to the dynamic braking action, the capacity of the series connection winding 102,
The residual magnetism created by the current flowing through the motor 202 can sufficiently contribute to making the motor work as a generator, so that the electric power generation operation can be performed reliably and the brake can be applied completely.

Also, contrary to the above, the other series-connected windings 102, 2
The switch is turned to O in the range t2 where the residual magnetism created by the current flowing through the
Even in the case of FF, the residual magnetism created by the current flowing through the series-connected windings 101 and 201 can be used to reliably perform the dynamic braking action in the same way as described above.

In particular, since the two series-connected windings constitute a part of both field windings 10 and 2o, respectively, one of the series-connected windings 101, 201 or 102, 20 may collapse.
Residual magnetism due to No. 2 will be generated in both field windings, and the dynamic braking effect will be even better.

As described above, the present invention eliminates all of the conventional drawbacks as a dynamic braking device for an AC commutator motor, such as being able to always apply a complete brake even when the switch is set to 0FFL and being safe. This is an excellent invention.

[Brief explanation of the drawing]

Fig. 1 is a waveform diagram of an alternating current, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a layout diagram of a field winding, and Fig. 4 shows two series-connected windings in a parallel relationship. A waveform diagram of the current flowing through the wire is shown. 1...Power supply, 10,20...Field winding, 101゜102.201.202-Universe winding, Ar-
・-・Armature, tl, t2...Range where residual magnetism cannot contribute to the dynamic braking action.

Claims (1)

[Claims] 1. An armature Ar having a winding, and a field winding 1 having a pair of magnetic poles.
0.20, and these armature Ar and both field windings 10.
20 is connected in series with power supply 1 during normal operation, and when dynamic braking is applied, power supply 1 is connected in series with power supply 1.
and a changeover switch sw that is disconnected and connected to form a dynamic braking circuit.
Two windings 101 and 102°2 with different numbers of turns, respectively.
01.202, one winding 101 in the field winding 10 of one pole and the other winding 201 of the field winding 20 of the other pole, and The other winding 102 and the coil winding 202 in the field winding 20 are connected in series, and further the windings 102, 2 are connected in series with the one series-connected winding set 1/01, 201.
02 are connected in parallel with each other. One of the series-connected windings 101 and 20 in this parallel relationship
1 and windings 102 and 202 connected in series, each having a phase difference between the currents flowing through the windings 102 and 202.