JPS5938016Y2 - Electromagnet exciter - Google Patents

Description

[Detailed explanation of the invention] This invention uses a large starting current to flow at the time of start-up.
This invention relates to an electromagnet excitation device that reliably attracts the magnet and, once the magnet is attracted, switches to continue to flow only a small holding current.

The object of the present invention is to construct this type of excitation device as compact, inexpensive, and versatile as possible.

To achieve this objective, the present invention enables the magnitude of the starting current, its conduction time, and the magnitude of the holding current to be switched and controlled by a simple electronic circuit. The illustrated embodiment will be described in detail.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 11 is an electromagnetic solenoid to be controlled, which is controlled by a DC power source obtained from an AC power source via a switch 12 and a single-phase bridge-connected rectifier circuit 13. Excited.

A voltage control thyristor 14 is connected in series to the solenoid 11, and a freewheeling diode 16 is connected in parallel.

This is the main circuit.

A resistor 21 and a Zener diode 22 are connected in series between the DC output terminals of the rectifier circuit 13, and a control DC voltage is obtained from both ends of the Zener diode 220.

One end of an ignition power supply capacitor 23 for ignition of the thyristor 14 is connected to the negative electrode side of this DC voltage source.

A first charging circuit 27 is provided between the positive electrode side of the DC voltage source and the other end of the ignition power supply capacitor 23, and includes a resistor 24 having a relatively low resistance value and a transistor 26 connected in series with the resistor 24.
, a second charging circuit 31 consisting of a resistor 28 having a relatively high resistance value and a transistor 29 connected in series thereto; a resistor 32 having a relatively high resistance value and a time-limiting capacitor 33 having a relatively large capacity connected in series thereto; and a time limit circuit 34 are connected in parallel with each other.

The emitters of both transistors 26, 29 are connected in common, the base of transistor 26 is connected to the collector of transistor 29, and the base-emitter circuit of transistor 29 is connected in parallel to timer 7'7-33.

A voltage dividing circuit 38 consisting of resistors 36 and 37 connected in series is connected across the DC voltage source, that is, the Zener diode 22.
is connected.

The ignition power supply capacitor 23 is connected to a pulse transformer 41 via a programmable unijunction transistor (hereinafter referred to as rPUTJ) 39 as its discharge circuit.
is connected.

A control pole of PUT 39 is connected to a voltage dividing point of voltage dividing circuit 38 .

The secondary circuit of the pulse transformer 41 is connected to the gate circuit of the thyristor 14. Now, in the illustrated circuit, when the switch 12 is turned on, the resistor 28, the transistor 26, and the capacitor 23 are turned on.
A base current flows in the circuit, the transistor 26 becomes conductive, and the capacitor 23 is rapidly charged through the first charging circuit 27 having a low resistance value.

At this time, the capacitor 23 is also charged from the shunt of the resistor 32 through the transistor 290 base circuit and the capacitor 33, but this charge is negligible compared to the amount of charging through the first charging circuit 27.

A predetermined divided voltage potential is applied to the control pole of the PUT 39 from the voltage dividing circuit 38, and when the main interelectrode voltage applied as the charging voltage of the capacitor 23 exceeds a predetermined value, the PUT 39
breaks over, and the capacitor 23 is discharged via the pulse transformer 41.

This causes the thyristor 14 to fire and the solenoid 11 to
Apply excitation current to.

The current in the thyristor 14 is naturally extinguished when it reaches zero every half wave, and is ignited each time as the capacitor 23 discharges.

This process is the start-up time, and by rapidly charging the capacitor 23 through the first charging circuit 27 with a low resistance value, the thyristor 14 causes a large start-up current to flow through the solenoid 11 at a conduction angle close to approximately 180 degrees, and the desired value is reached. Perform the sucking action quickly and reliably.

If it is desired to reduce the value of the starting current, the resistance value of the resistor 24 may be increased to increase the charging time constant of the capacitor 23.

In this way, while the starting current is flowing, the time limit circuit 3
The time limit capacitor 33 of No. 4 is gradually charged, and when the charging voltage reaches a predetermined value, the transistor 29 becomes conductive.

As a result, the transistor 26 is controlled to be off, and the charging circuit for the capacitor 23 is switched to the second charging circuit 31.

Since the resistor 28 of this charging circuit has a higher resistance value than the resistor 24, the capacitor 23 is charged more slowly.
Therefore, the conduction timing of PUT 39 is delayed, and the conduction angle of thyristor 14 is also narrowed.

Therefore, the holding current of the solenoid 11 given as the average current of the thyristor 14 is suppressed to a fraction of that at startup.

The magnitude of this holding current can be adjusted by changing the resistance value of the resistor 28. If the resistance value of the resistor 28 is increased, the charging time constant of the capacitor 23 is extended, the conduction angle of the thyristor 14 is narrowed, and the holding current is adjusted. becomes smaller.

Conversely, if the resistance value of the resistor 28 is lowered, the conduction angle of the thyristor 14 becomes wider and the magnitude of the holding current becomes larger.

Furthermore, as can be seen from the above explanation, the running time of the starting current, that is, the starting time, depends on the time constant of the time limit circuit 34, and by changing this time constant, an appropriate starting time can be set. .

When the switch 12 is opened after the electromagnet attraction process is completed, the excitation of the solenoid 11 is cut off, and the capacitor 33 is discharged through the base circuit of the transistor 290 to prepare for the next excitation process.

The device of the present invention described above is a so-called solid-state type device consisting of semiconductor elements and electrical parts such as resistors and capacitors, and can realize the desired automatic operation with a compact and inexpensive configuration, and also has low starting current, time, and holding current. Setting changes are also extremely easy.

Furthermore, in the device of the embodiment, when the AC power supply voltage increases, the rise and fall of the voltage taken out from the Zener diode 22 becomes steeper, so a control DC voltage with a high average voltage can be obtained although the peak value does not change. When the power supply voltage decreases, the rise and fall of the voltage taken out from the Zener diode 22 also becomes slow, so that a control DC voltage with a low average voltage can be obtained although the peak value does not change.

Therefore, when the power supply voltage decreases, the device of the present invention automatically extends the charging time of the capacitor 33 and automatically extends the start-up time to ensure reliable suction operation.

FIG. 2 shows a modified embodiment mainly of the main circuit portion of the circuit arrangement of FIG. 1. In FIG.

In this embodiment, the rectifier circuit 13A for the electromagnet solenoid 11 and the rectifier circuit 13B for the ignition control circuit are separated, and only the electromagnet solenoid is connected to the DC side of the rectifier circuit 13A, and the thyristor shown in FIG. 14, that is, a bidirectional thyristor 17 is connected in series to the alternating current side of the rectifier circuit 13A instead of the reverse blocking thyristor.

A surge absorption protection circuit consisting of a series circuit of a resistor 18 and a capacitor 19 is connected to the thyristor 17 in parallel.

In this circuit, the rectifier circuit 13A also serves as the freewheeling diode 16 shown in FIG.

The other portions are substantially the same as those in FIG.

The circuit operation of the device shown in FIG. 2 is substantially the same as that of the device shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a connection diagram of one embodiment of the excitation device according to the present invention, and FIG. 2 is a connection diagram of another embodiment of the excitation device according to the present invention. 11...Electromagnetic solenoid, 12...Switch, 1
3.13A, 13B -- Single phase bridge rectifier circuit, 14
．． 17...Thyristor, 16...Freewheeling diode, 21.24,28,32,36°37.
...Resistance, 22...Zener diode, 23゜33
...Capacitor, 26,29...Transistor, 2
7... First charging circuit, 31... Second charging circuit,
34... Time limit circuit, 38... Voltage dividing circuit, 39...
Programmable unijunction transistor, 41
...Pulse transformer.

Claims (1)

[Claims for Utility Model Registration] 1. A single-phase full-wave rectifier circuit that receives power from an AC power source and supplies a DC excitation current to an electromagnetic solenoid, a thyristor connected in series to the excitation current circuit of the electromagnet solenoid, and a thyristor connected in series to the excitation current circuit of the electromagnetic solenoid. An ignition power supply capacitor for supplying ignition pulses is connected in series between this ignition power supply capacitor and the ignition circuit of the thyristor, and when the charging voltage of the ignition power supply capacitor reaches a predetermined value, The ignition power supply comprises a switching element that is switched on to supply a ignition pulse from the ignition power supply capacitor to the thyristor, a first resistor having a relatively low resistance value, and a first transistor connected in series thereto. a first charging circuit for the ignition power supply capacitor, a second charging circuit for the ignition power supply capacitor comprising a second resistor of relatively high resistance and a second transistor in series therewith; a timer circuit consisting of a resistor and a timer capacitor in series with the resistor and connected in parallel to the second charging circuit, the base voltage of the first transistor being given as the collector voltage of the second transistor; An electromagnet excitation device characterized in that the base voltage of the second transistor is given as the charging voltage of the time capacitor. 2. Excitation of the electromagnet according to claim 1, wherein the thyristor is disposed on the DC side of the rectifier circuit, and a FJ-wheeling diode is connected in parallel to the electromagnetic solenoid. Device. 3. The electromagnet excitation device according to claim 1, wherein the thyristor is bidirectional and is disposed on the alternating current side of the rectifier circuit.