JPH0722512U - Electromagnetic coil drive - Google Patents

Abstract

(57) [Summary] [Constitution] The voltage output circuit 13 includes a constant voltage circuit 7, a voltage detection circuit 8, a timer circuit 9, a gain circuit 10, a reference wave generation circuit 11, a comparison circuit 12, and a pulse output circuit 13.
The ON / OFF control of the operation coil 4 for exciting the electromagnet via the switching element 5 is performed by the pulse signal from the.
A constant voltage diode 6 ₂ flywheel circuit 6, the time from turning off the power supply voltage until the release is movable core,
Select so that the entire circuit is sufficiently longer than the time from the state where the holding pulse signal for adsorbing and holding the movable iron core is output to the state where the closing pulse signal for sucking the moving iron core can be output. Set up. [Effect] Even if a momentary power failure occurs in the power supply voltage, the closing pulse signal is always output before the movable iron core is completely released, which may cause the movable iron core to remain released. Absent.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a coil driving device for an electromagnet using an electronic circuit.

[0002]

[Prior art]

 For example, as a coil drive device for an electromagnet used in an electromagnetic switch, a large current is applied to an operating coil that excites the electromagnet so that the movable iron core can be attracted when the movable iron core is attracted and turned on. From the viewpoint of power consumption, it is preferable to control so that a small electric current for adsorbing and holding the movable core is supplied. As a conventional coil driving device for an electromagnet in consideration of such a situation, there is a circuit shown in FIG. 2 shown in Japanese Patent Application No. 1-036070.

A specific electrical configuration will be described with reference to FIG. A full-wave rectifier circuit 3 is connected to an AC power source 1 via a power switch 2. The full-wave rectifier circuit 3 is configured by connecting diodes 3 ₁ or 3 ₄ in a bridge connection, and the DC output terminal is connected to the DC buses 14 and 15. The FET 5 is of the MOS type grounded source type, and its drain is connected to the DC bus 14 via the operating coil 4 and its source is connected to the DC bus 15. A flywheel diode 6 ₁ is connected in parallel to the operation coil 4. The constant voltage circuit 7 is connected between the DC buses 14 and 15, and the output terminal for outputting the DC constant voltage is connected to the DC bus 16. The voltage detection circuit 8 is composed of resistors 8 ₁ to 8 ₅ , a capacitor 8 ₆ and an open collector type comparator 8 ₇ . A series circuit of resistors 8 ₁ and 8 ₂ is connected between the DC buses 14 and 15, and a capacitor 8 ₆ is connected in parallel to the resistor 8 ₂ . A series circuit of resistors 8 ₃ and 8 ₄ is connected between the DC buses 16 and 15. The common connection point of the resistors 8 ₁ and 8 _{2 and} the common connection point of the resistors 8 ₃ and 8 ₄ are connected to the non-inverting input terminal (+) and the inverting input terminal (−) of the comparator 8 ₇ , respectively, and are compared. The output terminal of the device 8 ₇ is connected to the DC bus 16 via the resistor 8 ₅ .

The timer circuit 9 is composed of resistors 9 ₁ to 9 ₆ , a capacitor 9 ₇ , a Zener diode 9 ₈ , a diode 9 ₉ and an open collector type comparator 9 ₁₀ . A series circuit of resistors 9 ₁ , 9 ₂ , and 9 ₃ is connected between the DC buses 14 and 15, a capacitor 9 ₇ is connected in parallel to the resistor 9 ₃ , and a series circuit of resistors 9 ₂ and 9 ₃ is connected in parallel. The Zener diode 9 ₈ is connected. A series circuit of resistors 9 ₄ and 9 ₅ is connected between the DC buses 16 and 15, and the common connection point of the resistors 9 ₂ and 9 _{3 and} the common connection point of the resistors 9 ₄ and 9 ₅ are not connected to the comparator 9 ₁₀ . The inverting input terminal (+) and the inverting input terminal (-) are connected to each other, and the connection terminal of the comparator 9 ₁₀ is connected to the DC bus 16 via the resistor 9 ₆ . The non-inverting input terminal (+) of the comparator 9 ₁₀ is connected to the DC bus 16 via the diode 9 ₉ .

The gain circuit 10 is composed of analog switches 10 ₁ and 10 ₂ , resistors 10 ₃ to 10 ₆ and an operational amplifier 10 ₉ for forming a differential amplifier circuit. Its to the inverting input terminal of the operational amplifier 10 ₉ (-) via a resistor 10 _3, which is connected to the common connection point of the resistors _81, 82, resistor 10 _third resistor 10 in parallel with the ₄ and the analog switch 10 ₁ is connected in series, and the gate of the analog switch 10 ₁ is connected to the output terminal of the comparator 9 ₁₀ . The non-inverting input terminal (+) of the operational amplifier 10 ₉ is connected to the common connection point of the resistors 10 ₅ and 10 ₆ , and the series circuit of the analog switch 10 ₂ and the resistor 10 ₇ is connected in parallel with the resistor 10 _5. , The gate of the analog switch 10 ₂ is connected to the output terminal of the comparator 9 ₁₀ . Further resistance 1 0 ₈ the inverting input terminal of the operational amplifier 10 ₉ (-) and that is connected between the output terminal.

The reference wave generation circuit 11 is connected between the DC buses 16 and 15 and outputs a sawtooth wave V _S from an output terminal. The comparison circuit 12 is composed of an open collector type comparator 12 ₁ and a resistor 12 ₂ . The comparator 12 ₁ its non-inverting input terminal in (+) is connected to the output terminal of the reference wave generation circuit 11, an inverting input terminal (-) is connected to the output terminal of the operational amplifier _109, the output terminal resistor It is connected to the DC bus 16 through the 12 _2.

The pulse output circuit 13 is composed of an AND gate 13 ₁ and an amplifier 13 ₂ . In the ungate 13 ₁ , one input terminal is connected to the output terminal of the comparator 8 ₇ , the other input terminal is connected to the output terminal of the comparator 12 ₁ , and the output terminal is the gate of the FET 5 via the amplifier 13 _2. It is connected to the.

Next, the operation of the coil driving device will be described with reference to FIGS. 3 to 5. First, when the power switch 2 is turned on, the AC voltage of the AC power supply 1 is supplied to the full-wave rectifier circuit 3, and the full-wave rectifier circuit 3 performs full-wave rectification on the full-wave rectifier circuit 3 to obtain a DC output voltage, that is, a power supply voltage. , 15 between them. As a result, the constant voltage circuit 7 obtains a DC constant voltage from this power supply voltage and outputs it between the DC buses 16 and 15, and the DC constant voltage between the DC buses 16 and 15 is detected by the voltage detection circuit 8 and the timer. It is supplied to the circuit 9, the gain circuit 10, the reference wave generation circuit 11, the comparison circuit 12, and the pulse output circuit 13. When the supply voltage between the DC bus 14 and 15 is supplied to the voltage detection circuit 8, the power supply voltage is to be divided by the resistors _81, 82, thus the common connection of resistors _81, 82 From the point, the voltage is divided and smoothed by the capacitor 8 ₆ , and the detection voltage V _D proportional to the power supply voltage is output. This detection voltage V _D is applied to the non-inverting input terminal (+) of the comparator 8 ₇ and also to the gain circuit 10.

To the inverting input terminal (−) of the comparator 8 ₇ , a set voltage V ₈ obtained by dividing the constant DC voltage between the direct current buses 16 and 15 by the resistors 8 ₃ and 8 _{4 is} applied. The set voltage V ₈ is set to be proportional to the constant value of the power supply voltage at which the operating coil 4 should be activated. Therefore, when the detection voltage V _D is less than the set voltage, the output of the comparator 8 ₇ is low level (potential level of the DC bus 15), and one input signal of the AND gate 13 ₁ of the pulse output circuit 13 is low level. Then, the AND gate 13 ₁ becomes inactive.

When the detected voltage V _D becomes equal to or higher than the set value V ₈ , the comparator 8 ₇ outputs the voltage establishment signal S _D which is a high level signal from the output terminal. The level of the voltage establishment signal S _D is actually the potential of the DC bus 16 via the resistor 8 ₅ . Since the voltage confirmation signal S _D is given as one input signal of the AND gate 13, the AND gate 13 ₁ becomes active.

When the power supply voltage between the DC buses 14 and 15 is supplied to the timer circuit 9, the power supply voltage is divided by the resistors 9 ₁ , 9 ₂ and 9 ₃ to charge the capacitor 9 _7. Then, the detection voltage V ₁ is output. This detection voltage V ₁ is applied to the non-inverting input terminal (+) of the comparator 9 ₁₀ . The inverting input terminal (-) of the comparator 9 ₁₀ is supplied with a set voltage V ₉ obtained by dividing the direct current constant voltage between the direct current buses 16 and 15 by the resistors 9 ₄ and 9 ₅ , and detecting voltage V ₁ When the voltage exceeds the set voltage V ₉ , the time-up signal V _T is output. At the beginning of the operation of the timer circuit 9, the output of the comparator 9 ₁₀ is at a low level, so that the analog switches 10 ₁ and 10 ₂ are in a non-conducting state. Since the detection voltage V _D is also applied to the gain circuit 10 as described above, the detection voltage V _D is amplified by the amplification factor determined by the resistors 10 ₃ and 10 ₈ and the resistors 10 ₅ and 10 _6. It is output as a closing level signal SLa. The input level signal SLa is given to the inverting input terminal (-) of the comparator 12 ₁ in the comparison circuit 12. The non-inverting input terminal (+) of the comparator 12 ₁ is supplied with a sawtooth wave V _S having a constant period as shown in FIGS. 3 (a) and 4 (a) from the reference wave generating circuit 11, and The comparator 12 ₁ outputs a high-level closing pulse signal Pa during a period in which the sawtooth wave V _S is larger than the closing level signal SL a. The closing pulse signal Pa is given to the gate of the FET 5 through the AND gate 13 ₁ and the amplifier 13 ₂ in the active state in the pulse output circuit 13, and the F ET5 is turned on according to the closing pulse signal Pa. , It is turned off and the power supply voltage is intermittently supplied to the operation coil 4, so that the operation coil 4 excites the electromagnet, the movable iron core is attracted to the electromagnet, and the closing operation is completed.

After that, when the timer circuit 9 finishes the timed operation of the set time (time-up), the charging voltage of the capacitor 9 ₇ , that is, the detection voltage V ₁ exceeds the value of the set voltage V ₉ , and the output of the comparator 9 ₁₀ Becomes a high level, and this is given to the analog switches 10 ₁ and 10 ₂ as a time-up signal V _T. In this case, the set time of the timer circuit 9 is preset to a time sufficient for the electromagnet to attract the movable iron core and complete the closing operation. The time until the time-up is to change the voltage across the DC bus 14 and 15, the a constant in voltage over controlled than the Zener voltage of the constant voltage diode 9 _8. Then, the analog switches 10 ₁ and 10 ₂ become conductive. As a result, the resistors 10 ₄ and 10 ₇ are inserted in parallel with the resistors 10 ₃ and 10 ₅ , respectively. Therefore, the detection voltage V _D is amplified by the amplification factor determined by the resistors 10 ₃ , 10 ₄ and 10 ₈ and the resistors 10 ₅ , 10 ₇ and 10 ₆ and outputs the holding level signal SLb. In this case, the gain of the gain circuit 10 is larger when the holding level signal SLb is output than when the closing level signal SLa is output, and therefore the holding level signal SLb is higher than the closing level signal SLa. Become. Since the holding level signal SLb is supplied to the comparison circuit 12 like the closing level signal SLa, the holding circuit pulse signal Pb having a duty ratio smaller than that of the closing pulse signal Pa is output from the comparison circuit 12. It Since the holding pulse signal Pb is given to the gate of the FET 5 via the pulse output circuit 13, the FET 5 is turned on / off according to the holding pulse Pb to supply the operating coil 4 with the power supply voltage. And the movable iron core is adsorbed and held by the electromagnet.

By the way, when the AC voltage of the AC power source 1 is different, for example, in the case of a small voltage (for example, 100 V), a large voltage (for example, 200 V), and a medium voltage (for example, between the large voltage and the small voltage), the DC bus 14, The power supply voltage supplied between 15 also differs such as small, medium and large voltages, and the detection voltage V _D also changes like small, medium and large voltages. Therefore, the level signal SLa output from the gain circuit 10 also changes its level like S La ₁ (small voltage), SLa ₂ (medium voltage) and SLa ₃ (large voltage) as shown in FIG. However, the closing pulse signal Pa output from the comparison circuit 12 is also Pa ₁ (small as shown in FIGS. 3D, 3C, 5B and 5B, 5E, 5H). Voltage), Pa ₂ (medium voltage) and Pa ₃ (large voltage), the duty ratio changes, and the duty ratio gradually decreases.

The FET 5 to which these input pulse signals Pa ₁ , Pa ₂ or Pa ₃ are given via the pulse output circuit 13 is controlled to be turned on and off in accordance with each, and accordingly the operation coil 4 is controlled. 5 (c), (f) or (i), the power supply voltage is applied and the average applied voltage becomes almost constant, and the current flowing through the operating coil 4 is as shown in FIG. 5 (d), (g) or It becomes almost constant as shown in (j), and the closing operation is performed in which the electromagnet attracts the movable iron core.

After that, when the timer circuit 9 times up at times T ₁ , T ₂ and T ₃ corresponding to the small voltage, the medium voltage and the large voltage, respectively, and the amplification factor of the gain circuit 10 changes, the holding level thereof is held. The signal SLb changes its level like SLb ₁ (small voltage), SLb ₂ (medium voltage) and SLb ₃ (large voltage) as shown in FIG. The signal Pb is also Pb ₁ (small voltage), Pb ₂ (medium voltage) and Pb as shown in FIGS. 4 (d), (c), (b) and FIGS. 5 (b), (e) and (h). _The duty ratio changes like ₃ (large voltage) and gradually decreases. The FET 5 to which these holding pulse signals Pb ₁ , Pb ₂ or Pb ₃ are given via the pulse output circuit 13 is controlled to be turned on and off in accordance with each, and accordingly, the operation coil 4 has the operation shown in FIG. As shown in (f) or (i), the power supply voltage is applied and the average applied voltage becomes lower than that at the time of making the voltage substantially constant, and the current flowing through the operating coil 4 is as shown in FIG. 5 (d), (g) or (j). ), It becomes almost constant, and the electromagnet adsorbs and holds the movable iron core. After that, when the power switch 2 is turned off, the power supply voltage is not applied to the operation coil 4, so that the movable iron core is released.

[0016]

[Problems to be solved by the device]

 However, in such a coil drive device, a momentary power failure of a few tens of ms for the power supply voltage occurred while the movable iron core was attracted and held by the power supply voltage being applied. In this case, there was a problem that the movable iron core remained in the released state even when the movable iron core was released and the power supply voltage was restored from the power failure state and applied.

This is because the coil drive device side draws the movable iron core from the state in which the holding pulse signal for adsorbing and holding the movable iron core is output from the time from when the power supply voltage is turned off until the movable iron core is released. It takes longer for the closing pulse signal to be output, and even after the movable iron core is released, only the holding pulse signal can be output for a certain period of time. Because the iron core cannot be sucked, the movable iron core remains released.

Therefore, in the present invention, even if a momentary power failure occurs in the power supply voltage, after the movable iron core is released, a pulse signal for closing is always output to prevent the movable iron core from being released. An object of the present invention is to provide a coil driving device for an electromagnet.

[0019]

[Means for Solving the Problems]

 The electromagnet coil driving device of the present invention comprises an operating coil for exciting the electromagnet, a switching element which is turned on and off by a pulse signal to supply a power supply voltage to the operating coil, a voltage detection circuit for detecting the power supply voltage, A gain circuit that outputs a closing level signal according to the detection voltage of this voltage detection circuit, changes according to the input voltage, and outputs a holding level signal that is higher than the closing level signal based on the detection voltage after a set time. And a reference wave generating circuit that generates a triangular wave, compares the triangular wave of this reference wave generating circuit with the closing level signal of the gain circuit, outputs a closing pulse signal of a fixed cycle, and holds the triangular wave after the set time. Of the holding pulse signal whose duty ratio is smaller than that of the input pulse signal by comparing it with the input level signal. The pulse output circuit that supplies the input pulse signal and the holding pulse signal to the switching element, and the time until the movable iron core is released after the power supply voltage is turned off, the whole circuit holds the movable iron core by suction. It is equipped with a flywheel circuit with a constant voltage diode selected so as to be sufficiently longer than the time from the state in which the output pulse signal is output to the state in which a closing pulse signal for attracting the movable iron core can be output. It is characterized by

[0020]

According to the electromagnet coil drive device of the present invention, the entire circuit outputs a holding pulse signal for adsorbing and holding the movable iron core during the time from when the power supply voltage is turned off until the movable iron core is released. Since the constant voltage diode of the flywheel circuit was selected and provided so that it would be sufficiently longer than the time from when the flywheel circuit is ready to output the closing pulse signal for attracting the movable iron core, Even if a momentary power failure occurs, the moving iron core will always be released before the movable iron core is completely released, so that the movable iron core does not remain released.

[0021]

【Example】

An embodiment of the present invention will be described below. In Fig. 1, the basic circuit configuration is the same as that of Fig. 2 except that in the flywheel circuit 6, a parallel circuit of a constant voltage diode 6 ₂ and a transistor 6 ₃ is connected in series to the operation coil 4 and , The base of the transistor 6 ₃ is connected to the DC bus 15 via the resistor 6 ₄ , and the time from turning off the power switch 2 to releasing the movable core from the zener voltage of the constant voltage diode 6 ₂ is constituted. The time is set to be longer than the time it takes for the time-up signal V _T of the timer circuit 9 to go low after the power switch 2 is turned off.

If this Zener voltage is large, the current of the operating coil 4 can be rapidly attenuated, the release time of the movable iron core is shortened, and if the Zener voltage is small, the current of the operating coil 4 is slowly attenuated and the movable coil moves. The release time of the iron core is long.

According to this embodiment, when the power switch 2 is turned on, the transistor 6 ₃ is turned on, the power supply voltage controlled by the FET 5 is supplied to the operation coil 4, and the movable iron core is attracted and held. When the power switch 2 is turned off from this state, the time-up signal V _T does not immediately become low level due to the electric charge of the capacitor 9 ₇ of the timer circuit 9, and during this period, the gain circuit 10 and the comparator 12 are held respectively. The output level signal S Lb and the holding pulse signal Pb are output. However, when the charge of the capacitor 9 ₇ of the timer circuit 9 is discharged and the time-up signal V _T becomes low level, the gain circuit 10 and the comparator can output the closing level signal SLa and the closing pulse signal Pa, respectively. Becomes Therefore, by adopting a configuration in which the movable iron core is not released until such a state is reached, even if a momentary power failure occurs in the AC power supply 1, the movable iron core is held in the adsorbed state without being released. It will be.

[0024]

[Effect of device]

 According to the coil driving device of the electromagnet of the present invention, the movable iron core does not remain in the released state even if a momentary power failure occurs in the power supply voltage without changing the conventional circuit configuration. A coil driving device for an electromagnet can be provided.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a coil driving device for an electromagnet according to the present invention.

FIG. 2 is a circuit diagram showing a coil driving device for a conventional electromagnet.

3 (a) to (d) are waveform diagrams of a level signal for making depending on a small voltage, a medium voltage and a large voltage in the device of FIG.

4 (a) to (d) are waveform diagrams of a holding level signal according to a small voltage, a medium voltage, and a large voltage in the device of FIG.

5 (a) to (j) are signal waveform diagrams of respective parts according to a small voltage, a medium voltage and a large voltage in the device of FIG.

[Explanation of symbols]

1 is an AC power supply, 2 is a power switch, 3 is a full-wave rectifier circuit,
4 Coil, the FET 6 is flywheel circuit 5, 6 ₂ constant voltage diode, the constant voltage circuit 7, the voltage detecting circuit 8, the timer circuit 9, the 10 gain circuit, 1
Reference numeral 1 is a reference wave generation circuit, 12 is a comparison circuit, and 13 is a pulse output circuit.

Claims (1)

[Scope of utility model registration request] 1. An operating coil for exciting an electromagnet, a switching element which is turned on and off by a pulse signal to supply a power supply voltage to the operating coil, a voltage detection circuit for detecting the power supply voltage, and a voltage detection circuit for the voltage detection circuit. A gain circuit that outputs a closing level signal according to the detection voltage, changes according to the input voltage, and outputs a holding level signal higher than the closing level signal based on the detection voltage after a set time,
A reference wave generating circuit that generates a triangular wave is compared with the triangular wave of the reference wave generating circuit and the input level signal of the gain circuit to output an input pulse signal of a fixed cycle, and after a set time, the triangular wave and the holding level are output. A comparison circuit for comparing the signal and outputting a holding pulse signal having a duty ratio smaller than that of the closing pulse signal; and a pulse for supplying the closing pulse signal and the holding pulse signal of the comparison circuit to the switching element. The output circuit and the time from when the power supply voltage is turned off until the movable iron core is released, the input pulse for sucking the movable iron core from the state where the whole circuit outputs the holding pulse signal for adsorbing and holding the movable iron core. An electromagnet comprising a flywheel circuit having a constant voltage diode selected to be sufficiently longer than the time until a signal can be output. Coil drive.