JP2024157678A - Electromagnetic Device - Google Patents

Abstract

To provide an electromagnet device which prevents a voltage across a holding coil from being brought into a high voltage by an inverse current generated in the holding coil when a current is made flow only to a closing coil.SOLUTION: An electromagnet device comprises: a closing coil which is wound around a stationary iron core and excited by electrification to generate a magnetic flux and generates an electromagnetic adsorption force; a holding coil which is wound around the stationary iron core and excited by electrification to generate a magnetic flux in the same direction as the closing coil, generates an electromagnetic adsorption force and is connected in series with the closing coil and of which the resistance value is larger than that of the closing coil; a first switch of which one end is connected with a winding end of the closing coil and the other end is connected between a winding end of the holding coil and a negative side of a power source; a second switch which is provided between the winding end of the holding coil and the negative side of the power source; and a control circuit of which the voltage threshold is preset and which turns on the second switch in a case where a power supply voltage outputted by the power source satisfies the voltage threshold, and turns on the first switch simultaneously with or after timing in which the second switch is turned on.SELECTED DRAWING: Figure 1

Description

This disclosure relates to an electromagnetic device.

Conventionally, devices with a movable iron core and a fixed iron core, such as electromagnetic contactors, have used a technology that uses electromagnetic attraction force generated by passing a current through a coil made of copper wire wound around a magnetic material to attract the movable iron core to the fixed iron core.

In recent years, technology has been developed that uses two types of coils: an input coil that generates an electromagnetic attraction force that attracts the movable iron core of the electromagnetic contactor to the fixed iron core, and a holding coil that generates an electromagnetic attraction force that keeps the movable iron core attracted to the fixed iron core.

For example, Patent Document 1 discloses an electromagnetic operating device for a switching device that has two types of coils, a closing coil and a holding coil, and passes an excitation current only through the closing coil during attraction operation, and passes an excitation current through both the closing coil and the holding coil during attraction and holding.

JP 2012-216451 A

The electromagnetic operating device of the above-mentioned switchgear can reliably maintain the attraction state after the switchgear is closed by passing an excitation current through the closing coil and holding coil connected in series during attraction and holding. On the other hand, during attraction operation, the limit switch is separated from the holding coil and current is supplied only to the closing coil. At that time, an electromotive force is generated in the holding coil in a direction that cancels out the magnetic flux generated by the closing coil, and a current (hereinafter referred to as "reverse current") flows in the opposite direction to the winding direction of the copper wire of the holding coil. However, because the holding coil and the limit switch are separated, there is no place for the reverse current to escape, and the voltage across the holding coil becomes high.

The present disclosure has been made to solve the problems described above, and aims to provide an electromagnetic device that prevents the voltage across the holding coil from becoming high due to a reverse current generated in the holding coil when current is passed only through the closing coil.

The electromagnetic device according to the present disclosure includes a throw-in coil wound around a fixed iron core, which generates a magnetic flux when excited by energization to generate an electromagnetic attraction force; a holding coil wound around a fixed iron core, which generates a magnetic flux in the same direction as the throw-in coil when excited by energization to generate an electromagnetic attraction force, and which is connected in series with the throw-in coil and has a resistance value greater than that of the throw-in coil; a first switch having one end connected to the end of the throw-in coil and the other end connected between the end of the holding coil and the negative side of the power source; a second switch provided between the end of the holding coil and the negative side of the power source; and a control circuit having a preset voltage threshold, which turns on the second switch when the power source voltage output by the power source satisfies the voltage threshold, and turns on the first switch simultaneously with or after the second switch is turned on.

The electromagnetic device disclosed herein is provided with a first switch and a second switch, and a control circuit controls the on/off of the first switch and the second switch, which has the effect of preventing the voltage across the holding coil from becoming high due to a reverse current generated in the holding coil when current flows only through the closing coil.

1 is a configuration diagram of an electromagnetic device according to a first embodiment; 4 is a timing chart showing a time series change of the electromagnetic device according to the first embodiment; 5 is a diagram showing a time series change in the power supply voltage of a power supply included in the electromagnetic device according to the first embodiment. FIG. 5 is a diagram showing a time series change in an excitation current of a closing coil included in the electromagnetic device according to the first embodiment. FIG. 5 is a diagram showing a time series change in the voltage across the holding coil included in the electromagnetic device according to the first embodiment. FIG. 5 is a diagram showing a time series change in an exciting current of a holding coil included in the electromagnetic device according to the first embodiment. FIG. 10 is a diagram showing a time series change in the total value of ampere turns in the closing coil and the holding coil included in the electromagnetic device according to the first embodiment. FIG. 13 is a diagram showing a current flow at time t2 in the electromagnet device according to the first embodiment. FIG. 13 is a diagram showing a flow of a reverse current at time t3 in the electromagnetic device according to the first embodiment. FIG. FIG. 13 is a diagram showing a modified example of the electromagnetic device according to the first embodiment. FIG. 11 is a configuration diagram of an electromagnetic device according to a second embodiment. 10 is a timing chart showing a time series change of the electromagnetic device according to the second embodiment. 13 is a diagram showing a time series change in the power supply voltage of a power supply included in the electromagnetic device according to the second embodiment. FIG. 13 is a diagram showing a time series change in an excitation current of a closing coil of an electromagnetic device according to a second embodiment. FIG. 13 is a diagram showing a time series change in the voltage across both ends of the holding coil of the electromagnetic device according to the second embodiment. FIG. 13 is a diagram showing a time series change in an exciting current of a holding coil of an electromagnetic device according to a second embodiment. FIG. 13 is a diagram showing a time series change in the combined value of ampere turns in the closing coil and the holding coil of the electromagnetic device according to the second embodiment. FIG. FIG. 11 is a diagram showing a current flow at time t2 in the electromagnet device according to the second embodiment. FIG. 11 is a diagram showing a flow of a reverse current at time t3 in the electromagnetic device according to the second embodiment. FIG. 11 is a schematic diagram of an electromagnetic device according to a third embodiment. 13 is a diagram for explaining a path of a current that flows in association with excitation energy generated in a closing coil when a second switch included in an electromagnetic device according to a third embodiment is turned off. FIG. FIG. 13 is a schematic diagram of an electromagnetic device according to a fourth embodiment. 13 is a diagram for explaining a path of a current that flows in association with the excitation energy generated in the closing coil when a second switch included in the electromagnet device according to the fourth embodiment is turned off. FIG. 13 is a diagram for explaining a path of a current that flows in association with excitation energy generated in a holding coil when a second switch included in an electromagnetic device according to a fourth embodiment is turned off. FIG. 13 is a timing chart showing a time series change after time t4 of the electromagnet device according to the fourth embodiment.

The following describes the embodiments in detail with reference to the drawings. Note that the embodiments described below are merely examples. The embodiments can be implemented in appropriate combinations. In the following description, electrical connections and physical connections will not be distinguished from each other and will be referred to as "connections" unless a distinction is required.

Embodiment 1.
FIG. 1 is a schematic diagram of an electromagnetic device according to the present embodiment. FIG. 2 is a timing chart of the electromagnetic device according to the present embodiment. FIG. 3 is a diagram showing a time series change in the power supply voltage of a power supply included in the electromagnetic device according to the present embodiment. FIG. 4 is a diagram showing a time series change in the excitation current of a closing coil included in the electromagnetic device according to the present embodiment. FIG. 5 is a diagram showing a time series change in the voltage across both ends of a holding coil included in the electromagnetic device according to the present embodiment. FIG. 6 is a diagram showing a time series change in the excitation current of a holding coil included in the electromagnetic device according to the present embodiment. FIG. 7 is a diagram showing a time series change in the combined value of the ampere turns in the closing coil and the holding coil included in the electromagnetic device according to the present embodiment. FIG. 8 is a diagram showing a current flow at time t2 in the electromagnetic device according to the present embodiment. FIG. 9 is a diagram showing a reverse current flow at time t3 in the electromagnetic device according to the present embodiment. FIG. 10 is a diagram showing a modified example of the electromagnetic device according to the present embodiment.

First, the configuration of the electromagnet device 100 according to this embodiment will be described with reference to Figure 1. Note that the dotted lines connecting the control circuit 5 to the first switch 6 and the second switch 7 shown in Figure 1 are paths of signals sent when the control circuit 5 operates the first switch 6 and the second switch 7. Also, the arrows of the closing coil 1 and the holding coil 2 indicate the winding direction of the coils.

As shown in FIG. 1, the electromagnetic device 100 according to this embodiment includes a closing coil 1, a holding coil 2, a control circuit 5, a first switch 6, a second switch 7, flywheel diodes 8 and 9, a diode 10, and a power supply 11. Here, the diodes such as the flywheel diodes 8 and 9, which are connected in parallel with the closing coil 1 and the holding coil 2, respectively, and are provided to circulate the current that flows with the excitation energy after the power supply 11 is turned off, are generally called flywheel diodes. Therefore, in the following explanation, they will be referred to as flywheel diodes 8 and 9. However, the flywheel diodes 8 and 9 are switching diodes like the diode 10, for example, and are the same thing in themselves, and are merely described with different names.

The input coil 1 and the holding coil 2 are each wound around a fixed iron core 12 and connected in series. As shown in FIG. 1, the input coil 1 and the holding coil 2 are wound in the same direction, with the start of the input coil 1 connected to the positive side of the power source 11 and the end of the holding coil 2 connected to the negative side of the power source 11.

Therefore, when current is passed through the input coil 1 and holding coil 2, which are connected in series, magnetic flux is generated in the same direction in each fixed iron core 12 due to excitation by current passing through. The fixed iron core 12 attracts the movable iron core (not shown) due to the electromagnetic attraction force caused by this generated magnetic flux. The input coil 1, holding coil 2, fixed iron core 12, and movable iron core are arranged inside an electromagnetic coil (not shown).

In addition, the number of turns of the making coil 1 is smaller than that of the holding coil 2. In other words, the resistance value of the making coil 1 is smaller than that of the holding coil 2. Therefore, when comparing the case where a voltage is applied only to the making coil 1 with the case where a voltage is applied to the making coil 1 and holding coil 2 connected in series, a larger current flows and the number of ampere turns is larger when a voltage is applied only to the making coil 1. Therefore, by applying a voltage only to the making coil 1 during the attraction operation, the electromagnetic attraction force required to attract the movable iron core can be obtained. Note that the term "ampere turn" here refers to the unit of magnetomotive force in the MKSA system of units, expressed as the product of the current value and the number of turns.

As shown in FIG. 1, one end of the first switch 6 is connected to the end of the making coil 1, and the other end is connected between the end of the holding coil 2 and the negative side of the power source 11. The second switch 7 is also connected between the end of the holding coil 2 and the negative side of the power source 11. Specifically, one end of the second switch 7 is connected to the end of the holding coil 2, and the other end is connected to the negative side of the power source 11. Here, the negative side of the power source 11 refers to the negative pole side of the power source 11.

The control circuit 5 performs the switching operation of the first switch 6 and the second switch 7. The location of the control circuit 5 is not particularly important, but it is preferable to place it in a position where, for example, a surge voltage generated by the back electromotive force is not applied within the reverse recovery time of the flywheel diodes 8 and 9 when the first switch 6 and the second switch 7 are turned off.

Next, the switching operation from off to on performed by the control circuit 5 will be described. The control circuit 5 has a preset voltage threshold for determining that the electromagnet device 100 is within an operable voltage range, and turns on the second switch 7 when the power supply voltage output by the power supply 11 satisfies the voltage threshold. The control circuit 5 also turns on the first switch 6 at the same time as or after the second switch 7 is turned on. In other words, the control circuit 5 does not need to turn on the first switch 6 before the second switch 7 is turned on.

Next, the on-to-off switching operation performed by the control circuit 5 will be described. After turning on the first switch 6, the control circuit 5 turns off the first switch 6 when the time required to attract the movable iron core to the fixed iron core 12 has exceeded. That is, the time required to attract the movable iron core to the fixed iron core 12 is preset as a time threshold in the control circuit 5, and the control circuit 5 turns off the first switch 6 when the time threshold is exceeded. Also, when the voltage of the power source 11 from this state drops below the voltage required for attraction and holding, that is, when the power source 11 is intentionally turned off to stop the attraction and holding, or when the voltage of the power source 11 drops unintentionally, the control circuit 5 turns off the second switch 7 at the same time as or after the timing at which the first switch 6 is turned off.

The flywheel diodes 8 and 9 circulate the current that flows in response to the excitation energy generated in each of the closing coil 1 and the holding coil 2 when the second switch 7 is turned off, and are connected in parallel with each of the closing coil 1 and the holding coil 2. As shown in FIG. 1, the flywheel diode 8 is connected in parallel with the closing coil 1, the anode of the flywheel diode 8 is connected to the end of the winding of the closing coil 1, and the cathode of the flywheel diode 8 is connected to the start of the winding of the closing coil 1. Similarly, the flywheel diode 9 is connected in parallel with the holding coil 2, the anode of the flywheel diode 9 is connected to the end of the winding of the holding coil 2, and the cathode of the flywheel diode 9 is connected to the start of the winding of the holding coil 2.

The diode 10 is provided to protect the positive side of the power supply 11 from a surge voltage generated by the back electromotive force during the reverse recovery time of the flywheel diodes 8 and 9 when the first switch 6 and the second switch 7 are turned off. That is, as shown in FIG. 1, the anode of the diode 10 is connected to the positive side of the power supply 11, and the cathode of the diode 10 is connected to the beginning of the winding of the closing coil 1.

Next, the operation of the electromagnet device 100 will be explained with reference to Figures 2 to 9. Note that Figure 2 shows a timing chart, and Figures 3 to 7 show (a) to (e) of Figure 2 separately. In Figures 2 to 7, the horizontal axis represents time, and the waveforms shown by dashed lines represent prior art documents, while the waveforms shown by solid lines represent the present embodiment. However, when there is no difference in waveform between the dashed and solid lines, as in Figures 3 and 4, only the solid lines are shown.

As shown in FIG. 2, at time t1, the power supply 11 is turned on and the power supply voltage is applied. After that, at time t2, the control circuit 5 compares the power supply voltage applied by the power supply 11 with a preset voltage threshold, and if it determines that the applied power supply voltage exceeds the voltage threshold, it turns on the second switch 7. When the second switch 7 is turned on, the excitation current flows in the order of the power supply 11, the diode 10, the closing coil 1, the holding coil 2, and the second switch 7, as shown by the dashed arrow in FIG. 8.

Next, at time t3, the control circuit 5 turns on the first switch 6, and the power supply voltage of the power supply 11 is applied to the closing coil 1 via the diode 10, causing an excitation current that is larger than the excitation current that flowed before time t3 to flow through the closing coil 1. This starts the attraction operation of the movable iron core.

When the movable core starts to be attracted, the excitation current generated in the closing coil 1 causes an excitation current in the holding coil 2 to flow in the opposite direction to the excitation current generated in the closing coil 1, i.e., a reverse current. The reverse current flows in a loop through the first switch 6, the second switch 7, and the holding coil 2, as shown by the dashed arrow in Figure 9.

As shown in Figures 2 and 4, when the first switch 6 is turned on at time t3, the excitation current flowing through the closing coil 1 increases. This excitation current generates an electromotive force in the holding coil 2 in a direction that cancels out the magnetic flux generated by the closing coil 1, and a reverse current flows. As described above, in the prior art, there is no route for the reverse current to flow and the current remains, so the voltage across the holding coil 2 rises and becomes high, as shown in Figure 5. On the other hand, the electromagnetic device 100 of this embodiment has a route for the reverse current to flow, so the reverse current can flow without remaining there. This makes it possible to prevent the voltage across the holding coil 2 from becoming high due to the reverse current generated in the holding coil 2.

The control circuit 5 turns off the first switch 6 when the time required for the suction operation of the movable iron core is exceeded. Specifically, the time required from the start to the completion of the suction operation of the movable iron core is preset as a time threshold in the control circuit 5, and the control circuit 5 turns off the first switch 6 when it determines that the time threshold has been exceeded. The control circuit 5 also turns off the second switch 7 at the same time as or at a later time when the first switch 6 is turned off. Note that it is not limited to the control circuit 5 that turns off the second switch 7. For example, the second switch 7 may be turned off when the power source 11 goes out of power.

As described above, the electromagnetic device 100 according to this embodiment includes a throwing coil 1 wound around a fixed iron core 12, which generates a magnetic flux when excited by energization to generate an electromagnetic attraction force; a holding coil 2 wound around a fixed iron core 12, which generates a magnetic flux in the same direction as the throwing coil 1 when excited by energization to generate an electromagnetic attraction force, and which is connected in series with the throwing coil 1 and has a resistance value greater than that of the throwing coil 1; a first switch 6 having one end connected to the end of the throwing coil 1 and the other end connected between the end of the holding coil 2 and the negative side of the power source 11; a second switch 7 provided between the end of the holding coil 2 and the negative side of the power source 11; and a control circuit 5 having a preset voltage threshold, which turns on the second switch 7 when the power source voltage output by the power source 11 satisfies the voltage threshold, and turns on the first switch 6 at the same time as or after the second switch 7 is turned on. This configuration has the effect of preventing the voltage across the holding coil 2 from becoming high due to the electromotive force generated in the holding coil 2 as the excitation current flowing through the making coil 1 increases when a current flows only through the making coil 1.

In the present embodiment, for example, the control circuit 5 turns on the second switch 7 at time t2 and then turns on the first switch 6 at time t3, providing a time interval between time t2 and time t3. However, the first switch 6 and the second switch 7 may be turned on at the same time. The first switch 6 and the second switch 7 may also be turned off at the same time.

In addition, in this embodiment, the flywheel diode 9 is connected in parallel with the holding coil 2, but a diode 13 may be provided instead of the flywheel diode 9, as shown in FIG. 10, for example. Specifically, the anode of the diode 13 may be connected to the end of the holding coil 2 and the cathode to the start of the closing coil 1. Even in this case, it can play the same role as the flywheel diode 9.

Embodiment 2.
This embodiment will be described with reference to Figs. 11 to 19. Fig. 11 is a schematic diagram of an electromagnet device according to this embodiment. Fig. 12 is a timing chart of the electromagnet device according to this embodiment. Fig. 13 is a diagram showing a time series change in the power supply voltage of a power supply included in the electromagnet device according to this embodiment. Fig. 14 is a diagram showing a time series change in the excitation current of a closing coil included in the electromagnet device according to this embodiment. Fig. 15 is a diagram showing a time series change in the voltage across both ends of a holding coil included in the electromagnet device according to this embodiment. Fig. 16 is a diagram showing a time series change in the excitation current of a holding coil included in the electromagnet device according to this embodiment. Fig. 17 is a diagram showing a time series change in the combined value of the ampere turns in the closing coil and the holding coil included in the electromagnet device according to this embodiment. Fig. 18 is a diagram showing a current flow at time t2 in the electromagnet device according to this embodiment. Fig. 19 is a diagram showing a reverse current flow at time t3 in the electromagnet device according to this embodiment.

In the first embodiment, an electromagnet device 100 is shown that includes a making coil 1 and a holding coil 2 connected in series, a first switch 6, a second switch 7, and a control circuit 5, and the control circuit 5 controls the switching of the first switch 6 and the second switch 7, so that the reverse current generated in the holding coil 2 circulates without stagnating, and the voltage across the holding coil 2 is prevented from becoming high. In the second embodiment, an electromagnet device 101 is shown in which diodes 3 and 4 are newly provided. The rest of the configuration is the same as in the first embodiment, and the same components as in the first embodiment are given the same numbers and will not be described.

The electromagnetic device 101 according to this embodiment includes a throw-in coil 1 wound around a fixed iron core 12, which generates a magnetic flux when excited by energization to generate an electromagnetic attraction force; a holding coil 2 wound around the fixed iron core 12, which generates a magnetic flux in the same direction as the throw-in coil 1 when excited by energization to generate an electromagnetic attraction force, and which is connected in series with the throw-in coil 1 and has a resistance value greater than that of the throw-in coil 1; a first switch 6 having one end connected to the end of the throw-in coil 1 and the other end connected between the end of the holding coil 2 and the negative side of the power source 11; a second switch 7 provided between the end of the holding coil 2 and the negative side of the power source 11; and a control circuit 5 having a preset voltage threshold, which turns on the second switch 7 when the power source voltage output by the power source 11 satisfies the voltage threshold, and turns on the first switch 6 at the same time as or after the second switch 7 is turned on. This configuration has the effect of preventing the voltage across the holding coil 2 from becoming high due to the reverse current generated in the holding coil 2 as the excitation current flowing through the making coil 1 increases when current flows only through the making coil 1.

As shown in FIG. 11, the electromagnetic device 101 is also provided with diodes 3 and 4. Diode 3 is connected in series between the end of the closing coil 1 and the start of the holding coil 2. Specifically, the anode of diode 3 is connected to the end of the closing coil 1, and the cathode of diode 3 is connected to the start of the holding coil 2.

The diode 4 is connected in series between the winding start of the holding coil 2 and the winding start of the closing coil 1. Specifically, the anode of the diode 4 is connected to the winding start of the holding coil 2, and the cathode of the diode 4 is connected to the winding start of the closing coil 1.

Next, the operation of the electromagnetic device 101 will be described with reference to Figures 12 to 19. Note that Figure 12 shows a timing chart, and Figures 13 to 17 show (a) to (e) of Figure 12 separately. In Figures 12 to 17, the horizontal axis represents time, and the waveforms shown by dashed lines represent the electromagnetic device 100 shown in embodiment 1, and the waveforms shown by solid lines represent the electromagnetic device 101 shown in this embodiment. However, when there is no difference in the waveforms between the dashed and solid lines as in Figures 13, 14, etc., only the solid lines are shown.

As shown in FIG. 12, at time t1, the power supply 11 is turned on and the power supply voltage is applied. After that, at time t2, the control circuit 5 compares the power supply voltage applied by the power supply 11 with a preset voltage threshold, and if it determines that the applied power supply voltage exceeds the voltage threshold, it turns on the second switch 7. When the second switch 7 is turned on, the excitation current flows in the order of the power supply 11, diode 10, closing coil 1, diode 3, holding coil 2, and second switch 7, as shown by the dashed arrow in FIG. 18.

Next, at time t3, the control circuit 5 turns on the first switch 6, and the power supply voltage of the power supply 11 is applied to the closing coil 1 via the diode 10, causing an excitation current that is larger than the excitation current that flowed before time t3 to flow through the closing coil 1. This starts the attraction operation of the movable iron core.

When the movable iron core starts to be attracted, the excitation current generated in the closing coil 1 causes an excitation current in the holding coil 2 to flow in the opposite direction to the excitation current generated in the closing coil 1, i.e., a reverse current. As shown by the dashed arrow in Figure 19, the reverse current flows in a loop through the diode 4, the closing coil 1, the first switch 6, the second switch 7, and the holding coil 2. Note that because the diode 3 is provided, the reverse current does not flow in a loop through the second switch 7, the holding coil 2, and the first switch 6.

As shown in Figures 12 and 14, when the first switch 6 is turned on at time t3, the excitation current flowing through the closing coil 1 increases. This excitation current generates an electromotive force in the holding coil 2 in a direction that cancels out the magnetic flux generated by the closing coil 1, and a reverse current flows. By providing diodes 3 and 4, the electromagnetic device 101 of this embodiment can ensure a path for the reverse current to flow. This makes it possible to prevent the voltage across the holding coil 2 from becoming high due to the reverse current generated in the holding coil 2.

As shown in Figs. 12 and 16, in the electromagnetic device 101 according to this embodiment, a reverse current flows via a route that passes through the closing coil 1, but the reverse current flows only during the period when an excitation current flows through the closing coil 1 and the voltage at the start of the winding of the holding coil 2, which rises due to the electromotive force caused by the generated magnetic flux, becomes a voltage obtained by adding the forward voltage of the diode 4 to the voltage at the cathode of the diode 10. Therefore, the time during which the reverse current flows can be shortened compared to the electromagnetic device 100 according to the first embodiment. Furthermore, the rise in the voltage across the holding coil 2 can also be suppressed.

Furthermore, by shortening the time that the reverse current flows, as shown in Figures 12 and 17, the combined ampere-turn value of the closing coil 1 and the holding coil 2 can be increased more quickly in the electromagnetic device 101 of this embodiment than in the electromagnetic device 100 of embodiment 1, thereby shortening the attraction time of the movable iron core.

The control circuit 5 turns off the first switch 6 when the time required for the suction operation of the movable iron core is exceeded. Specifically, the time required from the start to the completion of the suction operation of the movable iron core is preset as a time threshold in the control circuit 5, and the control circuit 5 turns off the first switch 6 when it determines that the time threshold has been exceeded. The control circuit 5 also turns off the second switch 7 at the same time as or after the timing at which the first switch 6 is turned off.

As described above, the electromagnetic device 101 according to this embodiment is newly equipped with diodes 3 and 4. By providing diodes 3 and 4, the electromagnetic device 101 according to this embodiment forms a path that loops through the diode 4, the closing coil 1, the first switch 6, the second switch 7, and the holding coil 2, and the reverse current flows without stagnation. Therefore, with this configuration, when a current flows only through the closing coil 1, the reverse current electromotive force generated in the holding coil 2 due to the increase in the excitation current flowing through the closing coil 1 has the effect of suppressing the voltage across the holding coil 2 from becoming a high voltage.

In addition, the electromagnetic device 101 according to this embodiment is equipped with diodes 3 and 4, which shortens the time during which the reverse current flows. This not only suppresses the rise in the voltage across the holding coil 2, but also makes it possible to speed up the rise in the combined ampere-turn value of the closing coil 1 and the holding coil 2, thereby shortening the time it takes for the movable iron core to be attracted.

Embodiment 3.
This embodiment will be described with reference to Fig. 20 and Fig. 21. Fig. 20 is a schematic diagram of an electromagnetic device according to this embodiment. Fig. 21 is a diagram explaining a path of a current that flows in association with excitation energy generated in a closing coil when a second switch included in the electromagnetic device according to this embodiment is turned off.

In the second embodiment, an electromagnet device 101 is shown that includes flywheel diodes 8 and 9 for circulating the current that flows in association with the excitation energy generated in each of the closing coil 1 and the holding coil 2 when the second switch 7 is turned off. In the third embodiment, an electromagnet device 102 is shown in which the flywheel diode 8 is removed from the electromagnet device 101. The rest of the configuration is the same as in the second embodiment, and the same components as in the second embodiment are given the same numbers and will not be described.

The electromagnetic device 102 according to this embodiment includes a throw-in coil 1 wound around a fixed iron core 12, which generates a magnetic flux when excited by energization to generate an electromagnetic attraction force; a holding coil 2 wound around the fixed iron core 12, which generates a magnetic flux in the same direction as the throw-in coil 1 when excited by energization to generate an electromagnetic attraction force, and which is connected in series with the throw-in coil 1 and has a resistance value greater than that of the throw-in coil 1; a first switch 6 having one end connected to the end of the throw-in coil 1 and the other end connected between the end of the holding coil 2 and the negative side of the power source 11; a second switch 7 provided between the end of the holding coil 2 and the negative side of the power source 11; and a control circuit 5 having a preset voltage threshold, which turns on the second switch 7 when the power source voltage output by the power source 11 satisfies the voltage threshold, and turns on the first switch 6 at the same time as or after the second switch 7 is turned on. This configuration has the effect of preventing the voltage across the holding coil 2 from becoming high due to the electromotive force generated in the holding coil 2 as the excitation current flowing through the making coil 1 increases when a current flows only through the making coil 1.

When the attraction operation of the movable iron core is completed and the control circuit 5 turns off the second switch 7, the diodes 3 and 4 play a role in circulating the current that flows with the excitation energy generated in each of the closing coil 1 and the holding coil 2. In other words, the diodes 3 and 4 function as the flywheel diode 8 provided in the electromagnet device 101 in the second embodiment.

As shown in FIG. 21, when the control circuit 5 turns off the second switch 7, the current flowing due to the excitation energy generated in the closing coil 1 circulates along the route indicated by the dashed arrow. In detail, the current flowing due to the excitation energy generated in the closing coil 1 circulates through the closing coil 1, diode 3, and diode 4. Although not shown, the current flowing due to the excitation energy generated in the holding coil 2 circulates through the holding coil 2 and the flywheel diode 9.

As described above, the electromagnetic device 102 according to this embodiment includes diodes 3 and 4, which substitute for the role of the flywheel diode 8. Therefore, there is no need to include the flywheel diode 8, and the number of parts can be reduced.

Embodiment 4.
This embodiment will be described mainly using Figures 22 to 25, and also using Figure 21 as necessary. Figure 22 is a schematic diagram of an electromagnetic device according to this embodiment. Figure 23 is a diagram explaining the path of a current flowing in association with the excitation energy generated in the closing coil when a second switch included in the electromagnetic device according to this embodiment is turned off. Figure 24 is a diagram explaining the path of a current flowing in association with the excitation energy generated in the holding coil when a second switch included in the electromagnetic device according to this embodiment is turned off. Figure 25 is a timing chart showing the time series changes after time t4 of the electromagnetic device according to this embodiment.

In the second embodiment, an electromagnetic device 101 was shown that includes flywheel diodes 8 and 9 to circulate the current that flows in association with the excitation energy generated in each of the closing coil 1 and the holding coil 2 when the second switch 7 is turned off. In the fourth embodiment, an electromagnetic device 103 is shown in which the flywheel diodes 8 and 9 have been removed and a new diode 13 has been provided. The rest of the configuration is the same as in the second embodiment, and the same components as in the second embodiment are given the same numbers and will not be described.

The electromagnetic device 103 according to this embodiment includes a throw-in coil 1 wound around a fixed iron core 12, which generates a magnetic flux when excited by energization to generate an electromagnetic attraction force; a holding coil 2 wound around the fixed iron core 12, which generates a magnetic flux in the same direction as the throw-in coil 1 when excited by energization to generate an electromagnetic attraction force, and which is connected in series with the throw-in coil 1 and has a resistance value greater than that of the throw-in coil 1; a first switch 6 having one end connected to the end of the throw-in coil 1 and the other end connected between the end of the holding coil 2 and the negative side of the power source 11; a second switch 7 provided between the end of the holding coil 2 and the negative side of the power source 11; and a control circuit 5 having a preset voltage threshold, which turns on the second switch 7 when the power source voltage output by the power source 11 satisfies the voltage threshold, and turns on the first switch 6 at the same time as or after the second switch 7 is turned on. This configuration has the effect of preventing the voltage across the holding coil 2 from becoming high due to the reverse current generated in the holding coil 2 as the excitation current flowing through the making coil 1 increases when current flows only through the making coil 1.

As shown in FIG. 22, the electromagnet device 103 of this embodiment is different from the electromagnet device 101 of the second embodiment in that the flywheel diodes 8 and 9 are eliminated and a new diode 13 is provided. The diode 13 is provided in parallel connection between the start of the winding of the closing coil 1 and the end of the winding of the holding coil 2. Specifically, the anode of the diode 13 is connected to the end of the winding of the holding coil 2, and the cathode of the diode 13 is connected to the start of the winding of the closing coil 1.

When the attraction operation of the movable iron core is completed and the control circuit 5 turns off the second switch 7, a current is generated due to the excitation energy generated in each of the closing coil 1 and the holding coil 2. At that time, the current generated due to the excitation energy generated in the closing coil 1 flows in a circulation path shown by the dashed arrows in Figures 23 and 24. In this way, the current generated due to the excitation energy generated in the closing coil 1 flows in two paths: a path that circulates through the closing coil 1, diode 3, and diode 4 shown in Figure 23, and a path that circulates through the closing coil 1, diode 3, holding coil 2, and diode 13 shown in Figure 24.

Next, using FIG. 25, the timing charts after time t4 of the electromagnet device 102 according to the third embodiment and the electromagnet device 103 according to this embodiment are compared. In FIG. 25, (f) is the power supply voltage of the power supply 11, (g) is the excitation current of the closing coil 1, (h) is the excitation current of the holding coil 2, (i) is the total ampere-turn value, and the horizontal axis is time. Here, time t4 refers to the point in time when the second switch 7 is turned off. Note that in FIG. 25, the power supply 11 is turned off at time t4 and the second switch 7 is turned off, but the control circuit 5 may turn off the second switch 7 before the power supply 11 is turned off.

In the electromagnet device 102 according to the third embodiment, the only path through which the current generated by the excitation energy generated in the closing coil 1 flows is the path shown by the dashed arrow in FIG. 21. In this case, as shown in FIG. 25(g), when the voltage generated by the excitation energy in the holding coil 2 becomes smaller than the sum of the forward voltages of the diodes 3 and 4, the current in the holding coil 2 suddenly stops flowing. On the other hand, the electromagnet device 103 according to the present embodiment is provided with the diode 13, so that the current generated by the excitation energy generated in the closing coil 1 also flows through the path shown by the dashed arrow in FIG. 24 in addition to the path shown by the dashed arrow in FIG. 21.

The path indicated by the dashed arrow in FIG. 24 passes through holding coil 2, which has a higher resistance than closing coil 1, and thus the electromotive force of holding coil 2 is supplemented. As a result, the current circulates for a longer period of time than the path indicated by the dashed arrow in FIG. 21, which passes through closing coil 1 without passing through holding coil 2. Therefore, as shown in FIG. 25(g), in the electromagnet device 103 of this embodiment, the current also flows through the path indicated by the dashed arrow in FIG. 24, compared to the electromagnet device 102 of embodiment 3, so that the current can flow for a longer period of time and the energization time can be maintained longer.

As shown in FIG. 25(i), the combined ampere-turn value of the closing coil 1 and the holding coil 2 can be maintained for a long time in the electromagnet device 103 according to this embodiment compared to the electromagnet device 102 according to the third embodiment because the current generated by the excitation energy generated in the closing coil 1 after time t4 can be passed for a long time. This makes it possible to apply the electromagnet device 103 according to this embodiment to devices that require the movable core to be attracted and held as much as possible even after a power outage in the power source 11. Therefore, the electromagnet device 103 according to this embodiment is suitable for application to undervoltage tripping devices used in circuit breakers, for example, that perform tripping with a delay of about 0.5 to 3 seconds after a power supply voltage loss.

As described above, according to the electromagnet device 103 of this embodiment, a diode 13 is provided with an anode connected to the end of the winding of the holding coil 2 and a cathode connected to the beginning of the winding of the closing coil 1, so that it becomes easier to maintain the ampere turns required to attract and hold the movable iron core after the second switch 7 is turned off, and the device can be applied to devices that require the movable iron core to be attracted and held as much as possible even after a power outage.

Various aspects of this disclosure are summarized below as appendices.

(Appendix 1)
A closing coil is wound around a fixed iron core and generates a magnetic flux when excited by passing current through it, thereby generating an electromagnetic attraction force;
a holding coil wound around a fixed iron core, which generates a magnetic flux in the same direction as the throwing coil when excited by energization, thereby generating an electromagnetic attraction force, and which is connected in series with the throwing coil and has a resistance value greater than that of the throwing coil;
a first switch having one end connected to the end of the making coil and the other end connected between the end of the holding coil and the negative side of the power source;
A second switch provided between the end of the holding coil and the negative side of the power supply;
a control circuit that turns on the second switch when a power supply voltage output from the power supply satisfies a preset voltage threshold and turns on the first switch simultaneously with or after the second switch is turned on;
An electromagnetic device comprising:
(Appendix 2)
A first diode connected in series between the end of the closing coil and the start of the holding coil;
A second diode connected in series between the start of the winding of the holding coil and the start of the winding of the closing coil;
2. The electromagnetic device of claim 1, further comprising:
(Appendix 3)
3. An electromagnetic device as described in claim 2, wherein the first diode has an anode connected to the end of the winding of the closing coil and a cathode connected to the beginning of the winding of the holding coil, and the second diode has an anode connected to the beginning of the winding of the holding coil and a cathode connected to the beginning of the winding of the closing coil.
(Appendix 4)
4. The electromagnetic device according to claim 1, further comprising a flywheel diode connected in parallel with each of the closing coil and the holding coil.
(Appendix 5)
4. The electromagnetic device according to claim 2 or 3, further comprising a flywheel diode connected in parallel with the holding coil.
(Appendix 6)
4. The electromagnetic device according to claim 2 or 3, further comprising a third diode connected in parallel between an end of the holding coil and a start of the closing coil.
(Appendix 7)
7. The electromagnetic device according to claim 6, wherein the third diode has an anode connected to the end of the holding coil and a cathode connected to the beginning of the closing coil.
(Appendix 8)
A flywheel diode connected in parallel with the closing coil;
a third diode connected in parallel between the end of the holding coil and the beginning of the closing coil;
2. The electromagnetic device of claim 1, further comprising:
(Appendix 9)
9. The electromagnetic device according to claim 1, wherein the holding coil has a number of turns greater than that of the closing coil.
(Appendix 10)
10. The electromagnetic device according to claim 1, wherein the winding direction of the holding coil is the same as the winding direction of the closing coil.
(Appendix 11)
The control circuit has a preset time threshold, which is the time required for the movable iron core to be attracted to the fixed iron core, turns off the first switch when the time threshold is exceeded after the first switch is turned on, and turns off the second switch simultaneously with or after the first switch is turned off.

100, 101, 102, 103 Electromagnet device, 1 Closing coil, 2 Holding coil, 3, 4, 10, 13 Diode, 5 Control circuit, 6 First switch, 7 Second switch, 8, 9 Flywheel diode, 11 Power source, 12 Fixed iron core

Claims (11)

A closing coil is wound around a fixed iron core and generates a magnetic flux when excited by passing current through it, thereby generating an electromagnetic attraction force;
a holding coil wound around the fixed iron core, which generates a magnetic flux in the same direction as the throwing coil when excited by energization, thereby generating the electromagnetic attraction force, and which is connected in series with the throwing coil and has a resistance greater than that of the throwing coil;
a first switch having one end connected to the end of the closing coil and the other end connected between the end of the holding coil and the negative side of a power source;
a second switch provided between the end of the holding coil and the negative side of the power source;
a control circuit that turns on the second switch when a power supply voltage output from the power supply satisfies a preset voltage threshold and turns on the first switch simultaneously with or after the second switch is turned on;
An electromagnetic device comprising: a first diode connected in series between the end of the closing coil and the start of the holding coil;
a second diode connected in series between the start of the winding of the holding coil and the start of the winding of the closing coil;
The electromagnetic device of claim 1 further comprising: The electromagnetic device according to claim 2, wherein the anode of the first diode is connected to the end of the winding of the making coil and the cathode is connected to the beginning of the winding of the holding coil, and the anode of the second diode is connected to the beginning of the winding of the holding coil and the cathode is connected to the beginning of the winding of the making coil. The electromagnetic device according to claim 1, further comprising a flywheel diode connected in parallel with each of the closing coil and the holding coil. The electromagnetic device according to claim 2 or 3, further comprising a flywheel diode connected in parallel with the holding coil. The electromagnet device according to claim 2 or 3, further comprising a third diode connected in parallel between the end of the holding coil and the start of the closing coil. The electromagnetic device according to claim 6, wherein the third diode has an anode connected to the end of the holding coil and a cathode connected to the beginning of the closing coil. A flywheel diode connected in parallel with the closing coil;
a third diode connected in parallel between the end of the holding coil and the start of the closing coil;
The electromagnetic device of claim 1 further comprising: The electromagnetic device according to claim 1, wherein the holding coil has a greater number of turns than the closing coil. The electromagnetic device according to claim 1, wherein the winding direction of the holding coil is the same as the winding direction of the making coil. The electromagnet device according to claim 1, wherein the control circuit has a preset time threshold, which is the time required for the movable iron core to be attracted to the fixed iron core, turns off the first switch when the time threshold is exceeded after the first switch is turned on, and turns off the second switch at the same time as or after the first switch is turned off.

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