JPS5915455Y2 - electromagnet drive circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a drive circuit for an electromagnet used for various purposes, and is designed to increase the initial attraction force when an electromagnet attracts a movable iron core.

It is common practice to use electromagnets to operate mechanical elements.

In the case of DC electromagnets, it is also common practice to use DC obtained by rectifying AC as a power source.

It is known that an electromagnet has a characteristic that when the movable core is retracted, it generates a large attractive force, but when the core protrudes from the electromagnet and begins to be pulled, the attractive force decreases rapidly.

For this reason, if it was necessary to apply a large attraction force to a movable core located far from the electromagnet's maximum attraction point (the final attraction position if the movable core is a plunger type), conventionally it was necessary to use a large electromagnet. In addition, the power supply needed to have a large capacity.

FIG. 1 is a graph showing the relationship between the distance from the electromagnet's maximum attraction point of the movable iron core attracted by the electromagnet and the attraction force.

The curve ■ in the figure shows that when the movable core moves away from the maximum attraction point of the electromagnet, the attraction force weakens rapidly, and at a certain position α, the attraction force weakens to a fraction of
It shows that the degree of

Therefore, when the power supply voltage is increased and the current flowing through the electromagnet is increased, the attraction force increases overall and becomes as shown in the curve ■, but even at the final attraction position, the current is too much, and the heat generation increases and finally had the problem of burning out.

The present invention is an electromagnet with the characteristics shown by the curve ■, which supplies charged electricity to the capacitor so as to obtain a large attraction force when the movable core is separated, and also allows the rated current to be easily supplied in the attraction state. The present invention aims to provide a drive circuit for the following.

Next, an embodiment of the present invention will be explained with reference to FIG.
1 is a transformer, 2 is a primary coil, and 3 is a secondary coil.

The primary coil 2 is connected to a commercial AC power source.

The secondary coil has both ends connected to the first. It has second basic terminals A and B, and an intermediate tap 10 is provided at the midpoint thereof, and generates enough voltage to obtain the necessary attraction force when the movable core of the electromagnet 6, which will be described later, is separated. In addition, between the basic terminal A of the secondary coil 3 and the intermediate tap 10,
This is to generate the voltage necessary for continuous energization.

The first basic terminal A is provided with a first rectifying element 4 in the forward direction so that current flows from the first basic terminal A, and the second basic terminal B is provided with a first rectifying element 4 in the forward direction so that current flows from the first basic terminal A. A second rectifying element 8 in the opposite direction is connected so that the current flows into the second rectifying element 8 .

A resistor 7 is connected in series to the second rectifying element 8, and a switching element 5 and an electromagnet 6 are connected in series between the first rectifying element 4 and the resistor 7. .

Furthermore, a capacitor 9 is connected in parallel to the series circuit of the switch element 5 and the electromagnet 6, and this capacitor 9
between the connection point of the electromagnet 6 and the intermediate tap 10,
A third rectifying element 1 is arranged in the same direction (opposite direction) as the second rectifying element 8 so that current flows into the intermediate tap 10.
1 is connected.

Note that among these, the resistor 7 and the second rectifying element 8 may be connected in the reverse order.

This circuit configured in this manner operates as follows.

That is, when the switch element 5 is open, the capacitor 9 connects the first basic terminal A of the secondary coil 3 to the first rectifying element 4, the capacitor 9, the resistor 7, and the second rectifying element 8.
, the current flowing to the second basic terminal B of the secondary coil 3, and the current flowing from the first basic terminal A to the first rectifying element 4, the capacitor 9, the third rectifying element 11 . Charging is performed by both currents flowing through the intermediate tap 10.

Then, the voltage between the two electrodes of the capacitor 9 is finally the first voltage.
The voltage between the second basic terminals A and B reaches the negative voltage.

The voltage of capacitor 9 is connected between first basic terminal A and intermediate tap 1.
In a state where the voltage does not reach the peak voltage between 0 and 0, there is a period in which current passes through the third rectifying element 11, and charging is performed by both actions as described above.

After reaching the peak voltage between the first basic terminal A and the intermediate tap 10, the third rectifying element 11 always works to block the current, and the voltage between the first basic terminal A and the second basic terminal is Charging is performed only by the current flowing through B.

Next, when the switch element 5 is closed in order to use the electromagnet 6, a discharging current of the charge previously charged from the capacitor 9 flows through the electromagnet 6, and the electromagnet 6 is strongly excited.

Even during this discharge, the charging current continues to flow through the resistor 7, but since this current is much smaller than the discharging current, the potential of the capacitor 9 gradually decreases.

In this way, the discharge continues and the potential of the capacitor 9 reaches the first level.
When the voltage drops below the peak voltage between the basic terminal A and the intermediate tap 10, current will now flow through the electromagnet 6 through the third rectifying element 11, but this circuit has almost no resistance. Therefore, a constant current (see the part to the left of curve 2 in FIG. 1) flows through the electromagnet 6.

In this case, if the extraction point of the intermediate tap 10 in the secondary coil 3 of the transformer 1 is appropriately selected and the voltage generated at the intermediate tap 10 is appropriately set, the movable core can maintain its position after being pulled. can flow enough current.

FIG. 3 shows another embodiment of the present invention.

In this case, the intermediate tap 10 is connected to the first tap. second basic terminal A,
The rectifying elements 4' and 4' are added so that charging can be performed even when the two basic terminals A and B in FIG. 2 are exchanged.

Therefore, it corresponds to double-wave rectification in which charging is performed in both directions of the secondary side voltage.

The first rectifying elements 4', 4' act as ordinary double-wave rectifying elements when the electromagnet is energized.

Further, two resistors 7', 7' and two second rectifying elements 8', 8' are used, and are connected as shown in the figure.

In this circuit, there is a problem in that it is not possible to freely select the voltage at the start of drawing compared to the voltage required to continuously flow current through the electromagnet 6, but since a voltage approximately three times as large is obtained, it is not practical. It will be in a suitable state.

These rectifying elements and capacitors may be replaced with polarities such that current flows in opposite directions as a whole.

Further, the first rectifying element may be omitted in the embodiment shown in FIG.

In the embodiment described above, when the value of the capacitor 9 is large, a large portion of the curve (2) in FIG.

Since the present invention is configured as described above, it is possible to increase the initial attraction force when the electromagnet attracts the movable iron core, and in a stable state after attraction, the current is automatically controlled without the risk of heat generation or burnout. It has the advantage of being able to be maintained.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the distance of the movable iron core attracted by the electromagnet and the attraction force, Figure 2 is a circuit diagram of one embodiment of the present invention, and Figure 3 is a circuit diagram of another embodiment of the present invention. It is a diagram. 1.1'...Transformer, 2...Primary coil, 3, 3'...Secondary coil, 4.4', 8
．． 8', 11... Rectifying element, 5... Switch element, 6... Electromagnet, 7, 7'... Curved resistor, 9... Curved capacitor.

Claims (1)

[Scope of utility model registration request] Place both ends first. A first rectifier in the forward direction so that current flows from the first basic terminal to the first basic terminal of the secondary coil of the transformer, which is a second basic terminal and has a center tap at its midpoint. element to the second basic terminal, and the second
A second rectifying element is connected in the opposite direction so that a current flows into the basic terminal of the second rectifying element, and a resistor is connected in series with the second rectifying element, and the first rectifying element and
A switch element and an electromagnet are connected in series between the resistor and one end of the series circuit of the second rectifying element, and a capacitor is connected in parallel to the series circuit of the switch element and the electromagnet. An electromagnet drive circuit characterized in that a third rectifying element is connected between a connection point between the electromagnet and the intermediate tap, and the third rectifying element is oriented in the same direction as the second rectifying element so that a current flows into the intermediate tap. .