JPH07153626A - Electromagnet driving device - Google Patents

Abstract

PURPOSE:To reduce rapidly a current in an operating coil when an input supply voltage is reduced lower than the holding voltage of an electromagnet by a method wherein a third transistor to control the second transistor of a regenerative circuit parallel-connected to the coil is driven by the output of a voltage detecting part. CONSTITUTION:A transistor Tr3 to control a transistor Tr2 of a regenerative circuit K connected in parallel to an operating coil L is driven by an output of a voltage detecting part A. Accordingly, when an input supply voltage is reduced front a holding voltage of an electromagnet to a voltage lower than a second threshold value V2, an electromagnet drive signal Va is stopped by the part A and a transistor Tr1 is turned off. Simultaneously, the transistor Tr3 is also controlled into an OFF-state by the part A and the transistor Tr2 is turned off. As a result, an energy stored in the coil L passes through a diode D, which is parallel-connected to the transistor Tr2 and is series-connected with a power absorbing element Dz, to flow as a generative current, is consumed by the element Dz and a current in the coil L is rapidly reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for electromagnets used in electromagnetic relays, contactors and the like.

[0002]

2. Description of the Related Art Conventionally, as an electromagnet driving device of this type,
There is a configuration shown in FIG. 5 in which the voltage of each part changes in the time chart shown in FIG.

That is, this is a field effect type first transistor T connected in series to an operating coil L of an electromagnet.
r ₁ and the second transistor Tr ₂ and the Zener diode (power absorption element) Dz are connected in parallel to the diode D so that the regenerative current I ₁ flows when the first transistor Tr ₁ is off. A regenerative circuit K connected in parallel to the third transistor, a third transistor Tr ₃ driven by an input power supply voltage Vin to control the second transistor Tr ₂ , and an electromagnet drive when the input power supply voltage Vin exceeds a first threshold value V 1. The signal Va is output and the input power supply voltage Vin is the first threshold value V
The voltage detection unit A that stops the electromagnet drive signal Va when it falls below the second threshold value V2 set to 1 or less, and the predetermined time required for the electromagnet closing operation in conjunction with the electromagnet drive signal Va of the voltage detection unit A. A timer circuit B that generates a pulse Vb having a width t ₁ and a pulse Vc that generates a pulse Vc that drives the first transistor Tr ₁ at a predetermined period t ₂
A pulse Vc is used to switch the current I of the operating coil L to a required value when the electromagnet is turned on and when the electromagnet is turned on.
Pulse control circuit C for changing and controlling the duty ratio of
And are equipped with.

[0004]

In the above-mentioned conventional electromagnet driving device, the voltage detecting section A has the input power supply voltage Vin.
Detecting the first and second threshold values V1 and V2 of the electromagnet and outputting the electromagnet drive signal Va, and the timer circuit B interlocking with the electromagnet drive signal Va and the predetermined time width necessary for the electromagnet closing operation.
A pulse Vb of t ₁ is generated, and the pulse control circuit C changes the duty ratio of the pulse Vc so as to switch the current I of the operating coil L to a required value when the electromagnet is turned on and held, in synchronization with the pulse Vb. Therefore, the power consumption of the operating coil L can be reduced.

By the way, the third transistor Tr ₃ for controlling the second transistor Tr ₂ of the regenerative circuit K connected in parallel to the operating coil L is driven by the input power supply voltage Vin.

Therefore, the input power supply voltage Vin drops from the holding state of the electromagnet to fall below the second threshold value V2, the electromagnet driving signal Va of the voltage detecting section A is stopped, and the first transistor Tr ₁ is turned off. When the input power supply voltage Vin is sufficiently low, the third transistor Tr ₃ and the second transistor Tr ₂ are also turned off, and the energy stored in the operating coil L passes through the Zener diode Dz and the diode D. The regenerative current I ₁ flows and is consumed by the Zener diode Dz which is a power absorption element and rapidly decreases.

However, when the input power supply voltage Vin drops slowly, as shown in FIG. 6, the base voltage Vd of the third transistor Tr ₃ directly driven by the input power supply voltage Vin is immediately turned off. Since the second transistor Tr ₂ is also conducting, the regenerative current I ₁ flows through the second transistor Tr ₂ and the current I of the operating coil L does not immediately decrease.

As a result, the release time of the electromagnet becomes long, and the contact opening speed of a relay or the like using the electromagnet becomes slow, which may cause a failure in shutting off the switching load.

Also, when the input power supply voltage Vin is applied below the second threshold value V2 from the holding state of the electromagnet, the first
Although the transistor Tr ₁ is in the off state, the second transistor Tr ₂ and the third transistor Tr ₃ are in the on state, which causes the same problem as described above.

The present invention has been made in view of the above circumstances, and an object of the present invention is to set the input power supply voltage to the second level.
It is an object of the present invention to provide an electromagnet driving device that can quickly reduce the current of the operation coil when it is below the threshold value.

[0011]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, a first transistor connected in series to an operating coil of an electromagnet, a second transistor and a power absorption element are connected in parallel. A regenerative circuit connected in parallel to the operating coil so that a regenerative current flows when the diode is connected in series to the circuit and the first transistor is in the off state, the third transistor for controlling the second transistor, and the input power supply voltage is the first A voltage detection unit that outputs an electromagnet drive signal when the threshold value is exceeded, and stops the electromagnet drive signal when the input power supply voltage falls below a second threshold value that is set below the first threshold value, and the output of the voltage detection unit And a timer circuit that generates a pulse of a predetermined time width in conjunction with the operation pulse of the operation coil that generates a pulse that drives the first transistor at a predetermined cycle. In an electromagnet driving apparatus comprising: a pulse control circuit for switching control of the flow to a predetermined value, and has a structure in which the third transistor is driven by the output of the voltage detection unit.

Further, unlike the invention according to claim 1, the invention according to claim 2 has a structure in which the third transistor is driven by the output of the voltage detection section and the output of the timer circuit. There is.

[0013]

According to the first aspect of the present invention, the third transistor for controlling the second transistor of the regenerative circuit connected in parallel to the operating coil is driven by the output of the voltage detection unit, so When the input power supply voltage falls below the second threshold value, the voltage detection unit stops the electromagnet drive signal to turn off the first transistor, and at the same time,
The third transistor is also turned off by the voltage detection unit, and the second transistor is turned off. As a result, the energy stored in the operating coil is connected in series with the power absorption element connected in parallel to the second transistor. It flows as a regenerative current through the diode and is consumed by the power absorbing element to decrease rapidly, that is, the current in the operating coil decreases rapidly.

According to another aspect of the present invention, the base voltage of the third transistor driven by the output of the voltage detection unit and the output of the timer circuit is high when the output voltages of the voltage detection unit and the timer circuit are both High. Compared to when the electromagnet at the level is turned on, only the output voltage of the timer circuit decreases when holding the electromagnet, which changes to the low level, and as a result, when holding the same large current as when the magnet is turned on.
It doesn't have to flow to the transistor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The members having substantially the same functions as those of the conventional example are designated by the same reference numerals.

Tr ₁ is a first transistor, which is of a field effect type and is connected in series to an operating coil L of an electromagnet to which an input power supply voltage Vin is applied.

K is a regenerative circuit, in which a diode D is connected in series to a parallel circuit of the second transistor Tr ₂ and a Zener diode (power absorption element) Dz.
Are connected in parallel to the operation coil L.

The current I of the operating coil L flows as the current I ₂ due to the input power supply voltage Vin when the first transistor Tr ₁ is in the on state, but when the first transistor Tr ₁ is in the off state. the energy stored in L is, as a regenerative current I _1, flows through the transistor Tr ₂ is through its second transistor Tr ₂ and the diode D is turned on, but the second transistor Tr ₂ is turned off and a Zener diode Dz Zener diode D that is a power absorption element while flowing through the diode D
It is consumed by z and decreases rapidly.

Tr ₃ is a third transistor, the collector of which is connected to the base of the second transistor Tr _{2 and} the base of which is connected to the output of a voltage detection unit A which will be described later. That is, the third transistor Tr ₃ is driven by the electromagnet drive signal Va which is the output of the voltage detection unit A and controls the second transistor Tr ₂ .

Reference numeral A is a voltage detection unit which outputs an electromagnet drive signal Va when the input power supply voltage Vin exceeds the first threshold value V1, and the input power supply voltage Vin is set below the first threshold value V1. 2 When it falls below the threshold value V2, the electromagnet drive signal Va
To stop.

Reference numeral B is a timer circuit, which generates a pulse Vb having a predetermined time width t ₁ required for the electromagnet closing operation in synchronization with the electromagnet drive signal Va of the voltage detection unit A.

C is a pulse control circuit, which generates a pulse Vc at a predetermined cycle t ₂ , and the field effect type first transistor Tr through the AND gate of the pulse Vc and the electromagnet drive signal Va of the voltage detection unit A. _{In addition} to being connected to the gate of ₁ , the operating coil L is linked to the output pulse Vb of the timer circuit B to a value required when the electromagnet is turned on and held.
The duty ratio of the pulse Vc is changed and controlled so as to switch the current I.

Next, the operation of this electromagnet driving device will be described. In FIG. 2, when the input power supply voltage Vin rises from the zero level and exceeds the first threshold value V1, the voltage detection unit A outputs the electromagnet drive signal Va and becomes the high level voltage. Output Vb of timer circuit B
Becomes a high level voltage for a predetermined time width t ₁ required for the closing operation of the electromagnet. During the predetermined time width t _1, the duty ratio is adjusted so that the output pulse Vc of the pulse control circuit C becomes the predetermined current required to apply the current I of the operating coil L. At this time, the electromagnet drive signal Va of the voltage detector A is
Since the output voltage is at the High level, the third transistor Tr ₃ driven by the output of the voltage detection unit A is turned on, the second transistor Tr ₂ is turned on, and the first transistor Tr ₁ is turned off. A regenerative current I ₁ flows from the emitter to the collector of the second transistor Tr ₂ . This makes it possible to control the on / off state of the first transistor Tr ₁ so that the current I of the operating coil L becomes a predetermined current when turned on.

Next, when the electromagnet completes the closing operation and the output Vb of the timer circuit B becomes a low level voltage after a predetermined time width t ₁ , the output pulse Vc of the pulse control circuit C changes the current I of the operating coil L to the electromagnet. The duty ratio is adjusted so that the predetermined current required for the adsorption and holding of is obtained. At this time, since the second transistor Tr ₂ is conducting similarly to the above-mentioned turning on, the regenerative current I ₁ can be stably flowed, and the current I of the operating coil L becomes a predetermined current when the electromagnet is held. It is possible to control the on / off of the first transistor Tr ₁ .

Here, when the input power supply voltage Vin is lower than the second threshold value V2, the voltage detection unit A causes the electromagnet drive signal V
When a is stopped, the output voltage becomes Low level, and the output pulse Vc to the first transistor Tr ₁ is immediately stopped through the AND gate. At the same time, the third transistor Tr ₃ driven by the output of the voltage detection unit A is connected to the voltage detection unit A.
Is turned off due to the low level of the output voltage, the second transistor Tr ₂ is also turned off, and the energy stored in the operating coil L passes through the Zener diode Dz and the diode D to generate the regenerative current I _1. The current, which is consumed by the Zener diode Dz, decreases rapidly, and thus the current I in the operating coil L decreases rapidly.

In such an electromagnet driving device, as described above, the third transistor Tr ₃ for controlling the second transistor Tr ₂ of the regenerative circuit K connected in parallel to the operating coil L is controlled.
Is driven by the output of the voltage detection unit A, and when the input power supply voltage Vin falls below the second threshold value V2 from the holding state of the electromagnet, the current I of the operating coil L rapidly decreases,
As a result, the release time of the electromagnet is shortened, and the contact opening speed of the relay or the like using the electromagnet is also increased, and the switching load breaking performance is improved.

Next, a second embodiment of the present invention will be described with reference to FIGS.
It will be described based on. The members having substantially the same functions as those in the first embodiment are designated by the same reference numerals, and only the differences from the first embodiment will be described.

That is, the third transistor Tr ₃ has a first
In the present embodiment, it is driven by the output of the voltage detection unit A, but in the present embodiment, it is driven by the output of the voltage detection unit A and the timer circuit B.
It is driven by the output of and.

More specifically, the base of the third transistor Tr ₃ is connected to the voltage detector A via the resistors R ₁ and R _2.
And the output of the timer circuit B, respectively.

Next, the operation of this electromagnet driving device will be described. In FIG. 4, the input power supply voltage Vin rises from the zero level to exceed the first threshold value V1, and the output Va of the voltage detection unit A and the timer circuit B are obtained in the same manner as in the first embodiment.
When the output Vb of the above becomes a high level voltage, the third transistor Tr ₃ driven by both outputs is turned on, the second transistor Tr ₂ is turned on, and the first transistor Tr ₁ is turned off. A regenerative current I ₁ flows from the emitter to the collector of the second transistor Tr ₂ . At this time,
A current flows from the emitter of the second transistor Tr ₂ through the base to the collector of the third transistor Tr ₃ to the emitter. As a result, although the potential of the emitter of the third transistor Tr ₃ rises, the output Va of the voltage detection unit A is increased.
And the output Vb of the timer circuit B from the resistor R ₁ and the resistor R
The base voltage Vd of the third transistor Tr ₃ having a voltage drop of ₂ is limited to a potential lower by the voltage between the base and emitter of the third transistor Tr ₃ , and thus the base current of the second transistor Tr ₂ is reduced. It is possible to limit the collector current of the third transistor Tr ₃ .

Next, the electromagnet completes the closing operation and the output Vb of the timer circuit B becomes a low level voltage, but the output Va of the voltage detection unit A is a high level voltage.
Since the transistor Tr ₃ is in the ON state and the second transistor Tr ₂ is also conductive, the potential of the emitter of the third transistor Tr ₃ rises in the same manner as when the electromagnet is turned on. Here, since the output Va of the voltage detection unit A is at a high level, while the output Vb of the timer circuit B is at a low level, the output Va of the voltage detection unit A and the timer circuit B are
The third base voltage Vd of the transistor Tr ₃ from the output Vb becomes a value the voltage drop in the resistors R ₁ and R _2, the above electromagnet becomes lower than the time of turn-on, the correspondingly third transistor Tr ₃ of the emitter The potential is also limited to a lower level, so that the base current of the second transistor Tr ₂ , that is, the collector current of the third transistor Tr ₃ can be switched and limited to a current smaller than that when the electromagnet is turned on.

Next, when the input power supply voltage Vin falls below the second threshold value V2, the voltage detection unit A causes the electromagnet drive signal V
When a is stopped, the output voltage becomes Low level, and the output pulse Vc to the first transistor Tr ₁ is immediately stopped through the AND gate. At the same time, the third transistor Tr ₃ driven by the output Va of the voltage detection unit A and the output Vb of the timer circuit B is in a low level because both outputs are in a low level, and the second transistor Tr ₂ is also turned off. Turns off.

Further, even when the input power supply voltage Vin falls below the second threshold value V2 while the timer circuit B outputs the pulse Vb having the predetermined time width t ₁ at the time of turning on, the voltage detection unit A Since the output pulse of the timer circuit B can be immediately stopped by the output, the same operation as described above can be obtained.

In the electromagnet driving device, as described above, the third transistor Tr ₃ is driven by the output of the voltage detection unit A and the output of the timer circuit B, and therefore is driven by the output of the voltage detection unit A. in addition to the effects of the first embodiment that is, at the time of holding electromagnets it is not necessary shed same large current as when introduced to the third transistor Tr _3, it eliminates a possibility of heating burning the third transistor Tr _3.

[0035]

According to the first aspect of the present invention, the third transistor for controlling the second transistor of the regenerative circuit connected in parallel to the operation coil is driven by the output of the voltage detection unit, so that the holding state of the electromagnet is eliminated. When the input power supply voltage falls below the second threshold value, the voltage detection unit stops the electromagnet drive signal to turn off the first transistor, and at the same time,
The third transistor is also turned off by the voltage detection unit and the second transistor is turned off, and as a result, the energy stored in the operating coil is connected in series with the power absorption element connected in parallel to the second transistor. It flows as a regenerative current through the diode and is consumed by the power absorption element and decreases rapidly, that is, the current in the operating coil decreases rapidly, which in turn increases the release time of the electromagnet, which in turn uses the electromagnet. The contact opening speed of relays etc. is also increased, and the breaking performance of the switching load is improved.

According to a second aspect of the present invention, in addition to the effect of the first aspect, the base voltage of the third transistor driven by the output of the voltage detection unit and the output of the timer circuit is Both output voltages of the timer circuit are High
Compared to when the electromagnet at the level is turned on, only the output voltage of the timer circuit changes to a low level when the electromagnet is held, and as a result, when holding the same large current to the third transistor as when it was turned on. It is not necessary to flow it, and there is no possibility that the third transistor will be burned by heat.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a time chart showing a voltage change of the above.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a time chart showing a voltage change of the above.

FIG. 5 is a circuit diagram showing a conventional example.

FIG. 6 is a time chart showing a voltage change of the above.

[Explanation of symbols]

Tr ₁ 1st transistor Tr ₂ 2nd transistor Tr ₃ 3rd transistor Vin Input power supply voltage V1 1st threshold value V2 2nd threshold value A Voltage detection part Va Electromagnet drive signal (output of voltage detection part) B Timer circuit Vb Pulse (output of timer circuit) t ₁ Predetermined time width C Pulse control circuit Vc Pulse (output of pulse control circuit) t ₂ Predetermined period L Operating coil I ₁ Operating coil current K Regeneration circuit Dz Zener diode (power absorption element) D Diode I ₁ regenerative current

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[Procedure amendment]

[Submission date] December 1, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

K is a regenerative circuit, in which a diode D is connected in series to a parallel circuit of the second transistor Tr ₂ and a Zener diode (power absorption element) Dz.
Are connected in parallel to the operation coil L. The Zener
Diodes are used as power absorption elements instead of varistors and resistors.
You can get it.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Next, the operation of this electromagnet driving device will be described. In FIG. 4, the input power supply voltage Vin rises from the zero level to exceed the first threshold value V1, and the output Va of the voltage detection unit A and the timer circuit B are processed in the same manner as in the first embodiment.
When the output Vb of the above becomes a high level voltage, the third transistor Tr ₃ driven by both outputs is turned on, the second transistor Tr ₂ is turned on, and the first transistor Tr ₁ is turned off. A regenerative current I ₁ flows from the emitter to the collector of the second transistor Tr ₂ . At this time,
A current flows from the emitter of the second transistor Tr ₂ through the base to the collector of the third transistor Tr ₃ to the emitter. As a result, the potential of the emitter of the third transistor Tr ₃ rises, but the output Va and the output Vb are
Output the difference Vb to the value divided by resistors R ₁ and R _2.
From the base voltage Vd of the third transistor Tr ₃ which is a value obtained by adding the above value to a potential lower by the voltage between the base and emitter of the third transistor Tr ₃ and thus the second voltage.
It is possible to limit the base current of the transistor Tr ₂ , that is, the collector current of the third transistor Tr ₃ .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Then, the electromagnet completes the closing operation and the
The output Vb of the mer circuit B becomes a low level voltage.
Since the output Va of the pressure detector A is a high level voltage,
Transistor Tr₃Is on and the second transistor
Tr₂Since it is also conducting, the above electromagnet is the same as when it was turned on
Then, the third transistor Tr₃Potential of the emitter rises
To do. Here, the output Va of the voltage detection unit A is at High level
On the other hand, the output Vb of the timer circuit B is at low level
Because there isThe difference between the output Va and the output Vb is the resistance R ₁And
Add output Vb to the value divided by anti-R ₂ Value
Third transistor Tr₃The base voltage Vd of
The magnet becomes lower than when it was turned on, and the third transistor
Tr₃The emitter potential of is also limited to a lower
2 transistor Tr₂Base current of the third transition
Star Tr₃The collector current of is smaller than when the electromagnet is turned on
It is possible to switch and limit the current.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of Codes] Tr ₁ First Transistor Tr ₂ Second Transistor Tr ₃ Third Transistor Vin Input Power Supply Voltage V1 First Threshold V2 Second Threshold A Voltage Detector Va Electromagnet Drive Signal (Output of Voltage Detector) ) B timer circuit Vb pulse (output of timer circuit) t ₁ predetermined time width C pulse control circuit Vc pulse (output of pulse control circuit) t ₂ predetermined cycle L operating coil I operating coil current K regeneration circuit Dz Zener diode (power) Absorption element) D diode I ₁ regenerative current

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A diode is connected in series to a parallel circuit of a first transistor and a second transistor and a power absorption element connected in series to an operation coil of an electromagnet so that a regenerative current flows when the first transistor is in an off state. A regenerative circuit connected in parallel to the operating coil, a third transistor for controlling the second transistor, an electromagnet drive signal is output when the input power supply voltage exceeds the first threshold value, and the input power supply voltage is the first threshold value. A voltage detection unit that stops the electromagnet drive signal when it falls below a second threshold value set below, a timer circuit that generates a pulse of a predetermined time width in conjunction with the output of the voltage detection unit, and a first circuit at a predetermined cycle. A pulse control circuit for generating a pulse for driving one transistor, and interlocking with the output of the timer circuit to switch and control the current of the operation coil to a predetermined value;
In the electromagnet drive device including: an electromagnet drive device, wherein the third transistor is driven by an output of the voltage detection unit. 2. A diode is serially connected to a parallel circuit of a first transistor and a second transistor and a power absorption element connected in series to an operation coil of an electromagnet so that a regenerative current flows when the first transistor is in an off state. A regenerative circuit connected in parallel to the operating coil, a third transistor for controlling the second transistor, an electromagnet drive signal is output when the input power supply voltage exceeds the first threshold value, and the input power supply voltage is the first threshold value. A voltage detection unit that stops the electromagnet drive signal when it falls below a second threshold value set below, a timer circuit that generates a pulse of a predetermined time width in conjunction with the output of the voltage detection unit, and a first circuit at a predetermined cycle. A pulse control circuit for generating a pulse for driving one transistor, and interlocking with the output of the timer circuit to switch and control the current of the operation coil to a predetermined value;
In the electromagnet drive device including: an electromagnet drive device, wherein the third transistor is driven by an output of the voltage detection unit and an output of the timer circuit.