JPH06103647B2 - Electromagnet drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electromagnet driving device used in, for example, an electromagnetic contactor, in which a continuous current is applied to an electromagnet operating coil when the electromagnet is turned on, and an intermittent operation is performed when the electromagnet is held. The present invention relates to an electromagnet drive device in which the electric current consumption is reduced by switching the current to an intermittent current that holds the attraction of the iron core after it is attracted to the iron core.

[Conventional technology]

A conventional device of this type is shown in FIG. 3, and the AC voltage of the single-phase AC power supply 1 is applied to the AC terminal of the full-wave rectifier circuit 9 composed of a diode bridge circuit by turning on the closing switch 2. The DC terminal of the full-wave rectifier circuit 9 is connected to a series circuit of the electromagnet operating coil 5 and the collector-emitter passage of the switching transistor 6, and is also connected to the drive circuit 7. 3 is a noise absorption capacitor, 4
Is a flywheel diode. The drive circuit 7 is the fourth
As shown in the time chart in the figure, when the closing switch 2 is turned on, a pulse having a constant time width T necessary for attracting the movable iron core of the electromagnet (hereinafter, a pulse for continuing the ON state in this manner is called a continuous pulse). Is applied to the base of the switching transistor 6, and after the movable iron core is attracted, a pulse that repeatedly turns on and off at a period required to hold the movable iron core (hereinafter, a pulse that repeatedly turns on and off in this manner is an intermittent pulse). Switching transistor 6
Give to the base of. As a result, the electromagnet operating coil 5
Since the intermittent current is applied to the motor after the movable core is attracted, the power consumption can be reduced.

[Problems to be Solved by the Invention]

As described above, the switching transistor 6 is caused to perform a switching operation in order to reduce the power consumption, and the noise absorbing capacitor 3 is connected in order to remove the switching noise due to this switching operation. The noise source is the electromagnet operating coil 5 that is switching the electromagnet operating coil 5, and the electromagnet operating coil 5 is electrically insulated from the mounting base (earth) of the electromagnetic contactor by a case. However, they are coupled by stray capacitance at high frequencies, and the electromagnet operating coil 5 is electrically insulated from the iron core and the main contacts of the electromagnetic contactor, but at high frequencies it is stray. Coupled by capacitance. By the way, when the switching noise (high frequency noise) directly radiates in the air as a radio wave (radiates from the electromagnet operating coil through the iron core) and flows to the ground (radiation), it propagates through the power supply line of the single-phase AC power supply 1. When going (conducting), leakage to the power supply line (for example, in the case of an electromagnetic contactor, the power supply line connected to the main contact driven by the electromagnet operating coil) (the electromagnetic contactor from the electromagnet operating coil through the iron core) It is conceivable that the high-frequency noise leaked to the main contact of the (radiation) will radiate from the distribution line and flow to the earth (induction).
Is effective, but it has a drawback that the noise flowing to the ground as described above adversely affects external equipment.

Therefore, an object of the present invention is to provide a highly reliable electromagnet drive device that prevents adverse effects on external equipment due to switching noise without adding components such as a noise filter.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention is to connect a closing switch, an electromagnet operating coil and a switching element in series to a power source, and connect a noise absorbing capacitor in parallel to the electromagnet operating coil and the switching element, In an electromagnet drive device having a drive circuit that supplies a continuous pulse to the switching element when the electromagnet is turned on and supplies an intermittent pulse when the electromagnet is held, an iron core driven by the electromagnet operating coil is used as a noise absorbing capacitor for a power source. It is characterized in that it is electrically connected to a circuit on the electromagnet operating coil side.

[Action]

In the electromagnet driving device according to the present invention, the iron core driven by the electromagnet operating coil serves as a noise generation source by electrically connecting the iron core driven by the electromagnet operating coil to the circuit on the electromagnet operating coil side of the noise absorbing capacitor. Although the coil for electromagnet operation is electrically insulated from the mounting base (earth) of the electromagnetic contactor and the main contact by the case, even if it is coupled by stray capacitance in terms of high frequency,
When the switching noise from the electromagnet operating coil tries to flow to the ground or the main contact via the iron core, it is returned from the iron core to the noise absorbing capacitor on the power source side of the electromagnet operating coil, whereby the switching noise is grounded. Or flow to the main contact.

〔Example〕

1 and 2 are a circuit diagram showing an embodiment of the present invention and a side sectional view of an electromagnetic contactor to which the electromagnet of the present invention is applied. 1 and 2, the same parts as those of the conventional device shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

1 is different from the conventional device shown in FIG. 3 in that
The fixed iron core 1 of the iron cores driven by the electromagnet operating coil 5, that is, the fixed iron core 10a and the movable iron core 10b.
This is the point where 0a and the terminal A1 of the electromagnet drive circuit are electrically connected by the connection line 50. Also in this embodiment, switching noise is generated from the electromagnet operating coil 5 by the switching operation of the switching transistor 6 as in the conventional case. There is a floating capacitance between the electromagnet operating coil 5 and the fixed iron core 10a or the movable iron core 10b, between the fixed iron core 10a and the mounting base (earth) of the electromagnetic contactor, or between the movable iron core 10b and the main contact. The presence of the switching noise generated from the electromagnet operating coil 5 causes the fixed iron core 10a.
Through the movable iron core 10b to the main contact. However, the switching noise generated from the electromagnet operating coil 5 first flows into the iron core having a large coupling capacitance, and the switching noise flowing into the iron core is returned from the iron core to the noise absorbing capacitor 3 via the connecting wire 50 and the terminal A1. In this way, it is possible to prevent the switching noise generated in the electromagnet operating coil 5 from propagating through the floating electrostatic capacitance between the coil and the ground.

The capacitor 11 connected to the connecting wire 50 has a terminal A1 and a fixed iron core.
The voltage is divided so that the potential of 10a does not become the same. If the connection line 50 is connected to the terminal A2, that is, the switching transistor 6 side, there is a period in which the switching transistor 6 is off and the potential changes, so the effect of absorbing switching noise is reduced, so connecting to the terminal A1 side is recommended. desirable. Since the operation of the circuit shown in FIG. 1 is the same as that of the conventional device, its explanation is omitted.

FIG. 2 shows an electromagnetic contactor using an electromagnet according to the present invention. As is well known, the electromagnetic contactor is arranged in a frame 24 so as to face a fixed contactor 23 having a fixed contact 23a. A movable contact 22 having a movable contact 22a is attached to a movable contact support 20 via a contact spring 21, and the movable contact support 20 is connected to a movable iron core 10b.
A fixed iron core 10a is arranged so as to face the movable iron core 10b, and an electromagnet operating coil 5 wound around a winding frame 35 is arranged on the fixed iron core 10a.
Is installed. Reference numeral 26 denotes a case, and in this case 26, electric parts 27 such as resistors, capacitors, ICs, etc. are mounted, and a printed circuit board 25 having the connection shown in FIG. 1 is accommodated. In this case 26, electrical parts 27 and printed circuit board 25
In order to improve the moisture resistance and vibration resistance of the above, it is preferable to seal the whole with the casting resin 28. In addition, 29 is a return spring.

In FIG. 2, the connecting line 50 is again shown, and this connecting line 50
One end of which corresponds to the connection terminal 10c of the fixed iron core 10a, and the other end of which corresponds to the terminal A1 shown in FIG.
Soldered to a. The electromagnet operating coil 5 and the mounting base (ground) (not shown) are electrically insulated by the case 26, but are coupled by a floating electrostatic capacitance existing between them in terms of high frequency. Further, the electromagnet operating coil 5 and the main contact are also electrically insulated from each other, but in terms of high frequency, they are coupled by the floating electrostatic capacitance existing therebetween, and the iron core is a circuit of the electromagnet driving device. If it is not electrically connected to the power supply side of, the switching noise flows to the ground and the main contact due to the stray capacitance between the iron core and the ground and between the iron core and the main contact, which may adversely affect external equipment. However, in the present embodiment, the switching noise flowing in the iron core is returned to the noise absorbing capacitor 3 on the power source side of the circuit of the electromagnet driving device.

〔The invention's effect〕

As described above, according to the present invention, a closing switch, an electromagnet operating coil and a switching element are connected in series to a power source, and a noise absorbing capacitor is connected in parallel to the electromagnet operating coil and the switching element, In an electromagnet drive device having a drive circuit that supplies continuous pulses when the electromagnet is turned on to the switching element and supplies intermittent pulses when the electromagnet is held, an iron core driven by the electromagnet operation coil is used for noise absorption with respect to a power supply. By electrically connecting to the circuit on the electromagnet operating coil side of the capacitor, it is generated in the electromagnet operating coil by the switching operation of the switching element, and the floating electrostatic capacitance between the iron core and ground and the main contact causes the iron core to move. High frequency noise that is about to be propagated to the ground and main contact is transferred from the iron core to the electromagnet. Since it is possible to absorb flowing to the power supply side noise absorption capacitor of working windings, high frequency noise can be prevented from flowing to the ground and the main contacts. In addition, by connecting the iron core to the power supply side of the electromagnet drive coil via a capacitor, the potential of the power supply voltage is prevented from being applied to the iron core, the effect of absorbing high frequency noise and the electric shock when contacting the iron core are prevented. You can

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a side sectional view of an electromagnetic contactor to which the electromagnet of the present invention is applied, FIG. 3 is a circuit diagram showing a conventional device, and FIG. 3 is a time chart for explaining the operation of the circuit diagram of FIG. 3. 1: Power supply, 2: Switching switch, 3: Noise absorption capacitor, 5: Electromagnetic operation coil, 6: Switching transistor, 7: Drive circuit, 10a: Fixed iron core, 10b: Movable iron core, 11: Capacitor, 50: Connection line.

Claims (2)

[Claims] 1. A power supply, a closing switch, an electromagnet operating coil and a switching element are connected in series, a noise absorbing capacitor is connected in parallel to the electromagnet operating coil and the switching element, and when the electromagnet is turned on to the switching element. In an electromagnet drive device having a drive circuit for supplying continuous pulses and supplying intermittent pulses during holding, the iron core driven by the electromagnet operation coil is used as a power supply for an electromagnet operation coil rather than a noise absorption capacitor. An electromagnet driving device characterized by being electrically connected to a circuit on the side. 2. The electromagnet drive device according to claim 1, wherein the iron core is connected to the circuit via a capacitor.