JP2626147B2 - Drive device for electromagnet device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for an electromagnet device which saves power by energizing an excitation coil of the electromagnet device with a drive current intermittently switched by a switching means.

[Conventional technology]

FIG. 5 shows a conventional device of this type, in which the electromagnet device is turned on and released by a non-contact relay SSR.

In FIG. 5, T1 and T2 are input terminals to which an AC power supply is connected, and a non-contact relay S is connected in series with the input terminals T1 and T2.
The output terminals T3 and T4 of the SR are connected. Contactless relay SSR
The DC power supply E is connected to the input terminals T5 and T6 via the switch SW, and the light emitting diode of the phototriac coupler PT is connected. Photo triac coupler PT
The main triac TR is connected in parallel to the photo triac, and a resistor R11 is connected between the gate of the main triac TR and one terminal.
Is connected in parallel with a snubber circuit composed of a capacitor C10 and a resistor R10. A capacitor C1 and a diode bridge rectifier circuit DB are connected between the output terminal T4 of the contactless relay SSR and the input terminal T2 of the AC power supply, and the DC output terminal of the diode bridge rectifier circuit DB has an exciting coil of an electromagnet device.
A series circuit of the MC and the main transistor Tr1 is connected.
A flywheel diode is connected in parallel with the exciting coil MC.
D1 is connected.

The DC output terminal of the diode bridge rectifier DB
A series circuit of a resistor R1 and a zener diode ZD1 is connected to a series circuit of a resistor R2, a transistor Tr4 whose base is connected to a connection point between the zener diode ZD1 and the resistor R1, a diode D2, and a capacitor C2. Constructs a constant voltage circuit. A control circuit SS forming a switching control circuit is connected to a DC output terminal of the diode bridge rectifier circuit DB via a resistor R3. This control circuit
The power of SS is supplied from a connection point between the capacitor C2 and the diode D2. The control circuit SS has a built-in voltage detection circuit for detecting a voltage input via the resistor R3. When the voltage detection circuit detects that the input voltage has reached a predetermined value, the control circuit SS detects the voltage of the transistor Tr2. Supply the intermittent pulse signal to the base. The collector of the transistor Tr2 is connected to the base of the transistor Tr3, and the emitter of the transistor Tr3 is connected to the base of the main transistor Tr1. The base of the transistor Tr2 is connected to the connection point between the capacitor c2 and the diode D2 via the resistor 6,
The collectors of the transistors Tr2 and Tr3 are connected to the capacitor C2 and the diode D2 via the resistors R5 and R4, respectively.
Is connected to the connection point.

Now, assuming that the AC power supply is connected to the input terminals T1 and T2 of the AC power supply and the switch SW connected to the input terminals T5 and T6 of the contactless relay SSR is turned on, the phototriac coupler PT of the contactless relay SSR is turned on. So the main triac
A current flows in the gate of TR, the main triac TR turns on, and an AC input voltage is applied to the diode bridge rectifier circuit DB. Until the voltage V1 full-wave rectified by the diode bridge rectifier circuit DB exceeds the Zener voltage of the Zener diode ZD1, the capacitor C2 is charged through the transistor Tr4, and the voltage V1 of the DC output terminal of the diode bridge rectifier circuit DB is a Zener diode. When the Zener voltage of ZD1 is exceeded, Zener diode ZD1 conducts and capacitor C
2 is charged with a charge substantially corresponding to the zener voltage of the zener diode ZD1 and is made constant. When the voltage detection circuit of the control circuit SS detects that the magnitude of the input voltage has reached a predetermined value, the control circuit SS firstly outputs 0 V of a fixed time width.
Alternatively, a negative pulse signal is applied to the base of the transistor Tr2 to turn off the transistor Tr2,
r3, the main transistor Tr1 turns on. As a result, a current flows through the exciting coil MC, and the electromagnet device is turned on. Control circuit
When the transmission of the pulse signal of a fixed time width from SS ends, the base current of the transistor Tr2 is supplied to the base of the transistor Tr2 via the resistor R6, so that the transistor Tr2 is turned on, and the transistor Tr3 and the main transistor Tr1 are turned off. After the electromagnet device is turned on, the transistor Tr2 is repeatedly turned on and off by the intermittent pulse signal output from the control circuit SS, so that the transistor Tr3 and the main transistor Tr1 are repeatedly turned on and off to apply the intermittent voltage to the exciting coil MC. As a result, a continuous holding current flows through the flywheel diode D1, and the power consumption of the input current is reduced. FIG. 6 shows the waveform of the AC input current of the driving device for such an electromagnet device. FIG. 6 (A) shows the input voltage, and FIG. 6 (B) shows the current flowing through the capacitor C1 and the current of the circuit excluding the capacitor C1. When the voltage drops below the ON voltage of the elements of the bridge rectifier circuit DB, the entire circuit is turned off.
The result is as shown in FIG. The sum of these two currents is the current of this driving device, as shown in FIG. 6 (C). As shown in the enlarged view of FIG. 7, the waveform sharply falls in the opposite direction near 0 V. Has become.

[Problems to be solved by the invention]

In the above-described conventional device, the input current is extremely small because the excitation coil MC is driven by the main transistor Tr1 with intermittent signals at regular time intervals.
As a result, when the conventional electromagnet device is driven using the non-contact relay SSR, the input current becomes less than the holding current of the main triac TR depending on the non-contact relay SSR. (Hereafter, a photo triac is issued for the main triac TR.
It may work only with PT). When this phenomenon occurs, the holding current of the phototriac PT is very small as compared with the main triac TR, and as shown in FIG. 7, the waveform becomes a waveform commutated to the leading current of the capacitor C1 in the vicinity of the holding current. , The time t1 shorter than the holding current is shortened. Due to such a cause, the phototriac PT cannot be turned off during the time t1, and the output side cannot be turned off even if the input side switch SW of the non-contact relay SSR is turned off, whereby the electromagnet device cannot be released. In this case, if a resistor is inserted between the input terminals T2 and T4 of the electromagnet device to increase the current flowing to the output side of the non-contact relay SSR and turn on the main triac TR of the non-contact relay SSR, this element is retained. Since the current is large and there is enough time to hold the current, the main triac TR is turned off by switching off the input side of the contactless relay SSR, and the electromagnet device is also released. However, this method has disadvantages in that the advantage of power saving of the electromagnet device is lost and that the capacity of the resistor must be increased because the power supply voltage is directly applied to the resistor.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional device, to save power by making the excitation coil intermittently a drive current, and to turn on and release the electromagnet device using a contactless relay. It is another object of the present invention to provide a driving circuit for an electromagnet device that can perform the above.

[Means for solving the problem]

In order to achieve the above-described object, the present invention has a switching control circuit that is driven via switching means by a pulse signal that interrupts energization of an excitation coil of an electromagnet device, and includes an excitation coil and an AC power supply of the electromagnet device. The electromagnetic switching device is turned on and off by turning on and off a main switching element of a contactless relay inserted between the relays. The region is set in an energized state or a non-energized state for a predetermined time longer than a cycle of an intermittent pulse signal output from the switching control circuit.

(Operation)

In the driving device of the electromagnet device of the present invention, the electromagnet device turned on by the non-contact relay has the excitation coil longer than the intermittent pulse signal output from the switching control device for each half-wave of the AC power supply. The main triac of the contactless relay is turned on by increasing the AC input current while keeping the energized state for a predetermined time, specifically, the switching means in the on state. Thus, when the switch on the input side of the contactless relay is turned off, the main triac is turned off at a point where the AC input current becomes equal to or less than the holding current of the main triac, and the output side of the contactless relay is turned off. Also, in an electromagnet device that is turned on by a non-contact relay, if the excitation coil is in a non-conductive state for a predetermined time longer than the intermittent pulse signal output from the switching control device, the AC input current does not have a photo-triac of the non-contact relay. During the period when the input current is zero, the phototriac of the non-contact relay is turned off and the output side of the non-contact relay is turned off. Thus, when the switch on the input side of the non-contact relay is turned off, the photo liac of the non-contact relay is turned off and the output side of the non-contact relay is turned off during the period when the AC input current is zero.

〔Example〕

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIGS. 1 and 3 are circuit diagrams of a driving circuit of an electromagnet device showing different embodiments of the present invention. The same components as those of the conventional example shown in FIG. Is omitted.

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The difference from the conventional example in the figure is that a capacitor C11 is first connected to the DC output terminal of a diode bridge rectifier circuit DB. The point is that the phase advanced current flowing near the voltage of 0 V is prevented. And the second difference is that the transistor
A Zener diode ZD2 is connected in series with a resistor R5 connected to the base of Tr3, and the other end of the Zener diode ZD2 is connected to a connection point between the emitter of the transistor Tr4 and the diode D2.

FIG. 2 shows a waveform diagram of a main part of the driving device of the electromagnet device shown in FIG. 1, and its operation will be described with reference to the waveform diagram shown in FIG.

Now, when the switch SW connected to the input terminals T5 and T6 of the non-contact relay SSR is turned on and the non-contact relay SSR is turned on,
An input voltage as shown in FIG. 2 (A) is applied to the diode bridge rectifier circuit DB from the AC power supply, and the emitter voltage of the transistor Tr4 constituting the constant voltage circuit is shown in FIG. 2 (B).
As shown in FIG. 7, a voltage region exceeding the zener voltage of the zener diode ZD1 has a trapezoidal shape bypassed by the zener diode ZD1. In a period t2 in which the emitter voltage of the transistor Tr4 is lower than the zener voltage of the zener diode ZD2, no base current is supplied to the transistor Tr3, the transistor Tr3 is turned off, and the main transistor Tr1 is turned off. Accordingly, the AC input current of the diode bridge rectifier circuit DB becomes zero in the region of the period t2 as shown in FIG. 2 (C), so that the AC input current becomes less than the holding current of the phototriac PT of the contactless relay SSR. , The photo triac PT turns off. When the switch SW on the input side of the contactless relay SSR is turned off during the period t2 when the AC input current becomes zero, the phototriac PT and the main triac TR of the contactless relay SSR are turned off, and the electromagnet device is released.

(Embodiment 2) Next, FIG. 3 shows a different embodiment of the present invention. The difference between FIG. 3 and the conventional example shown in FIG. 5 is that first, the capacitor C11 is connected to the DC output of the diode bridge rectifier circuit DB. It is connected to the end, thereby preventing a phase-advanced current that conventionally flows near the power supply voltage of 0V. The second difference is that a Zener diode ZD3 is connected in series with a resistor R6 connected to the base of the transistor Tr2, and the other end of the Zener diode ZD3 is connected to the emitter of the transistor Tr4 and a diode D2 which constitute a constant voltage circuit. This is the point connected to the connection point with.

FIG. 4 shows a waveform diagram of a main part of the drive circuit of the electromagnet device shown in FIG. 3, and the operation will be described with reference to this waveform diagram.

Now, when the switch SW connected to the input terminals T5 and T6 of the non-contact relay SSR is turned on and the non-contact relay SSR is turned on,
An AC input voltage as shown in FIG. 4 (A) is applied to the diode bridge rectifier circuit DB from the AC power supply, and the emitter voltage of the transistor Tr4 constituting the constant voltage circuit is a voltage region exceeding the zener voltage of the zener diode ZD1. The trapezoid is bypassed by the diode ZD1. In a period t3 in which the emitter voltage of the transistor Tr4 is lower than the zener voltage of the zener diode ZD3, no base current is supplied to the transistor Tr2, the transistor Tr2 turns off, the transistor Tr3 turns on, and the main transistor Tr1 turns on. Therefore, the AC input current of the diode bridge rectifier circuit DB increases as shown in FIG. 4 (C) because the effective current has stopped switching in the region of the period t3,
When the main triac TR of the output image of the non-contact relay SSR is turned on and this AC input current falls below the holding current of the main triac TR, and the switch SW on the input side of the non-contact relay SSR is turned off, The main triac TR on the output side is turned off and the electromagnet device is released.

〔The invention's effect〕

As described above, according to the present invention, there is provided a switching control circuit that is driven via switching means by a pulse signal that intermittently energizes the excitation coil of the electromagnet device, and includes an excitation coil and an AC power supply of the electromagnet device. The electromagnetic switching device is turned on and off by turning on and off a main switching element of a contactless relay inserted between the relays. The region is configured to be in an energized state or a non-energized state for a predetermined time longer than the cycle of the intermittent pulse signal output from the switching control circuit, thereby preventing the electromagnetic relay from being released by the non-contact relay. can do. In addition, by energizing the excitation coil with a drive current intermittent by the switching control circuit, the power-saving electromagnet device can be turned on and off using a non-contact relay, and has advantages such as long life and maintenance-free. It is possible to use a contactless relay with

[Brief description of the drawings]

FIGS. 1 and 3 are circuit diagrams of a driving device of an electromagnet device showing different embodiments of the present invention, and FIGS.
5 is a waveform diagram of a main part of the circuit diagrams shown in FIGS. 1 and 3, respectively. FIG. 5 is a circuit diagram of a driving device of an electromagnet device showing a conventional device, and FIG. 6 is a main part of FIG. Waveform diagram,
FIG. 7 is an enlarged view of a portion A in FIG. 6 (C). SSR: Non-contact relay, MC: Excitation coil, SS: Control circuit, Tr1:
Main transistor, Tr2 to Tr4: transistor, TR: triac.

Claims (1)

(57) [Claims] A switching control circuit for driving the excitation coil of the electromagnet device through a switching means by a pulse signal which interrupts the supply of current to the excitation coil of the electromagnet device, and a switching control circuit inserted between the excitation coil of the electromagnet device and an AC power supply. In the one in which the electromagnet device is turned on and off by turning on and off the main switching element of the contact relay, the area near zero of the power supply voltage where the main switching element in the non-contact relay is equal to or less than the self-holding current is determined by the switching control circuit. A driving device for an electromagnet device, which is set in an energized state or a non-energized state for a predetermined time longer than a cycle of an intermittent pulse signal output from the controller.