JPS6015134B2 - Polarized electromagnet drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for a polarized electromagnet, such as a polarized electromagnet used to drive a polarized solenoid.

In recent years, polar solenoids have been increasingly used as organic electromagnets because they are advantageous in terms of power saving.

Furthermore, it is becoming increasingly common to use an easily available AC power source as a drive power source for such a solenoid, connect a rectifier circuit to this AC power source, and use the rectified output obtained through this circuit. Conventionally, as a drive circuit for this type of polarized electromagnet, as shown in FIG. A relay RY is connected to the IJ side, and a series circuit of a polarized electromagnet, such as a polarized solenoid SL, and a capacitor C is connected in parallel to the relay RY.
The switching point of relay RY is connected through the contact s-a of y, and the resistor R is connected in parallel to the series circuit through the saddle s-b of the switching contact ry, and by turning on the switch SW. Operate relay RY and switch contact ry of the same relay RY
Attach the solenoid SL through the pocket piece s-a to operate the self-holding operation, and then open the switch SW to activate the relay RY.
is restored, and the electric charge of the capacitor C is discharged through the switch s-b resistor R of the relay RY, and the solenoid S
There is one that allows L to return.

However, since such a drive circuit uses the contacts of the relay RY, contact failures are likely to occur, which is undesirable in terms of reliability. Furthermore, since the relay RY itself is large, the entire circuit is large and also expensive. Furthermore, since the relay RY is always connected to the power supply, the power consumption of the relay RY increases, and the effect of using a polarized solenoid to save power is diminished.The present invention was made to eliminate the above-mentioned drawbacks. With something that
The purpose of the present invention is to provide a drive circuit for a polar electromagnet that can improve reliability by making the circuit non-contact, can be made small and inexpensive, and can be expected to operate stably even with rectified output obtained from an AC power supply. do.

．． An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, AC is an alternating current power source, and a rectifier circuit, for example, a full-wave rectifier circuit SR, is connected to this alternating current power source AC via a switch SW.
Connect. A direct circuit of a polar electromagnet, for example, a polar solenoid SL, a capacitor C, and a diode O is connected to the output side of the rectifier circuit SR, and a resistor R2 is connected in parallel to this series circuit. The connection point between the diode D and the resistor R2 is connected to the base of a transistor Tr (an NPN transistor in the illustrated example), and the emitter of the transistor Tr is connected to the capacitor C. and diode D, the collector is connected to the resistor R, and the solenoid SL is connected to the resistor R.
Connect to the two connection points respectively. And the above diode D
Connect capacitor C2 in parallel with . Here, the resistance value of the above-mentioned self-resistance R differs depending on the return voltage of the solenoid SL, but normally in this type of circuit, the resistance value of the solenoid SL is 1
It is set in the range of ~3 times.

Also, the time constant of resistor R2 and capacitor C2 (7, = C2R
2) is set to a value sufficiently larger than the change time at the fall of the rectified voltage waveform generated on the output side of the rectifier circuit SR. Specifically, assuming that the AC power supply AC has 50 cycles, C2=10 French and R2=about several tens of KQ are used. In this case, the time constant of capacitor C and resistor R2 (2 = C, R2)
must be set sufficiently larger than the time constants of the capacitor C2 and resistor R2. Next, the operation of the drive circuit configured as above will be explained.

When the switch SW is turned on now, a full-wave rectified output is generated in the rectifier circuit SR. Then, solenoid SL-capacitor C. - An instantaneous current flows through diode D to operate solenoid SL, and at the same time capacitor C is charged to the polarity shown. Thereafter, when the charging of capacitor C is completed, the current is blocked and the energization of solenoid SL is released, but solenoid SL maintains its operating state. In this case, the full-wave rectified output on the output side of the rectifier circuit SL lowers the voltage waveform to zero every half wave.

Then, as the voltage waveform falls at this time, the discharge current of the capacitor C flows through the resistor R2 between the base and emitter of the transistor Tr.
It is recommended that the solenoid SL be turned on by mistake, causing the solenoid SL to return to its original state. However, in the circuit of the present invention, a capacitor C2 is connected in parallel with the diode D to form a sufficiently large time constant together with the resistor R2. Therefore, all of the discharge current from the capacitor C flows to the capacitor C2 and is charged there, so that malfunction of the transistor Tr is prevented, and erroneous recovery of the solenoid SL is reliably prevented. Next, when the switch SW is opened in this state, the rectifier circuit SR
The full wave rectified output of is stopped.

Then, the discharge current of capacitor C flows, but in this case, the time constant of capacitor C and resistor R2 is equal to capacitor C.
2 and the time constant 72 of resistor R2, the lightning protection current also flows to the base emitter of transistor Tr via solenoid SL and resistor. Therefore,
When the transistor Tr turns on, the self-discharge current flows as a return current of the solenoid SL through the collector-emitter of the transistor Tr, thereby returning the solenoid SL from its self-held special state to its original state. In this case, even if the AC power supply AAC is interrupted while the switch SW is on, the rectified output of the rectifier circuit SR is stopped, so that the solenoid SL can be quickly restored as described above.

If one end of the resistor R2 in Figure 2 is connected to the connection point between the solenoid SL and the capacitor C as shown in Figure 3, a small holding current will be generated through the solenoid SL and the resistor R2 even during the self-holding operation of the solenoid SL. flows, so the holding force of the solenoid SL can be increased accordingly.

Therefore, with such a configuration, since the circuit configuration can be made contactless using one transistor circuit, it is possible to improve the reliability of the circuit compared to the conventional circuit using a trailing point relay. The entire circuit can be made smaller and cheaper.

In addition, in such a configuration, resistor R2 is always connected to the power supply, but this resistor R2 has a sufficiently large resistance value so that the power consumption can be reduced, resulting in lower power consumption than in the case of conventional relays. By using a polarized solenoid, the advantages can be fully utilized. Furthermore, in the event of a power outage of the AC power source, the polarized solenoid can be quickly restored even if the switch is in the on state, so that the load driven by the solenoid can always be operated safely. Furthermore, even when a rectified output obtained from an AC power source is used, stable operation can be expected at all times because malfunction of the transistor due to the fall of the rectified voltage every half wave can be reliably prevented. This makes it possible to easily use an AC power source, which is extremely advantageous economically compared to preparing a dedicated DC power source. It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications within the scope without changing the gist.

For example, in the above-mentioned embodiments, the structure is made up of one transistor, but it is also possible to use a Darlington-connected transistor. Also, in the above, NPN
Although a type transistor is used, a PNP type transistor may also be used. Further, although the above description has focused on a polarized solenoid, it is also possible to apply the present invention to other polarized electromagnetic devices.
As described above, according to the present invention, an organic electromagnet that can improve reliability by having no contact with a circuit, can be made small and inexpensive, and can also be expected to operate stably even with rectified output obtained from an AC power source. drive circuit.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of a drive circuit for a subordinate organic electromagnet, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a circuit diagram showing an embodiment of the invention. Yes. AC...alternating current power supply, SW...switch, SR...
Rectifier circuit, RY...relay, SL...polarized solenoid,
C, C,, C2... Cosodenser, R, R,, R2...
・Resistance, D...diode, Tr"transistor. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An AC power source, a rectifier circuit connected to the AC power source, a capacitor charged in a predetermined direction by the rectified output of the rectifier circuit, and a transistor circuit turned on by the discharge current of the capacitor. a polarized electromagnet connected in series with the capacitor and energized and maintained in operation by the charging current of the capacitor, and reset by applying a discharging current of the capacitor after the transistor circuit turns on; and the rectified output. A driving device for a polarized electromagnet, comprising: a capacitor that charges the discharge current of the capacitor that occurs at the falling edge of every half wave of and prevents the on-operation of the transistor circuit. 2. The drive circuit for a polarized electromagnet as set forth in claim 1, further comprising a circuit that constantly supplies the rectified output of the rectifying circuit to the polarized electromagnet.