JP2024055468A - Power Supplies - Google Patents

Abstract

[Problem] To suppress inrush current while suppressing heat generation and efficiency reduction. [Solution] The present invention includes a DC-DC converter 3, a switch circuit 4 for switching an input DC voltage from the DC-DC converter 3, and an inrush current suppression circuit 6 connected between the DC-DC converter 3 and the switch circuit 4. The inrush current suppression circuit 6 is provided with a diode D5 disposed in a high potential line 61, the anode side of which is connected to the DC-DC converter 3, a resistive element R1 having one end connected to the high potential line 61 on the cathode side of the diode D5, a capacitor C1 having one end connected to the other end of the resistive element R1 and the other end connected to a low potential line 62, and a transistor Q for short-circuiting the resistive element R1. The transistor Q shorts the resistive element R1 when a voltage difference obtained by subtracting the anode side voltage V1 from the cathode side voltage V2 of the diode D5 exceeds a predetermined value (≧0V). [Selected Figure] FIG.

Description

The present invention relates to a power supply device that supplies a DC voltage to an inductive load.

Patent Document 1 discloses a power supply device that supplies a DC voltage to an electromagnet (inductive load) for deflecting and scanning a beam of charged particles emitted from an accelerator or the like. Such a power supply device includes a full bridge circuit (switch circuit) that receives a DC voltage from a rectifier (DC source) and outputs a DC voltage to be supplied to the electromagnet. By controlling the full bridge circuit, it is possible to adjust the amount of current output to the electromagnet and switch the polarity of the current.

JP 2020-137243 A

When the load is an inductive load such as an electromagnet, as in the power supply device disclosed in Patent Document 1, when an abnormality occurs and the protection circuit is activated, causing the switch circuit to stop operating, the energy stored in the load is regenerated as an induced electromotive force. Then, a regenerative current flows into the switch circuit.

One possible solution is to provide a capacitor with a capacitance corresponding to the load capacity between the switch circuit and the DC source that supplies DC voltage to the switch circuit, so that the regenerative current flows into the capacitor. However, if the capacitance of such a capacitor is increased, there is a risk that the charging current to the capacitor will become an inrush current when the DC source is started.

Therefore, it is necessary to place a resistive element to suppress the inrush current when the DC source is started. Such a resistive element is placed in series with the DC source between the DC source and the capacitor. In addition, by placing a switch element in parallel with such a resistive element, it is possible to avoid power loss in the resistive element during normal operation after charging of the capacitor is completed. In other words, by turning the switch element ON and shorting the resistive element during normal operation, it is possible to avoid power loss in the resistive element. However, such a switch element needs to be kept in the ON state during normal operation. Therefore, the switch element becomes hot due to heat generation. In addition, the efficiency decreases due to increased power consumption in the switch element.

The objective of the present invention is to provide a power supply device that has the function of absorbing regenerative current from an inductive load that occurs when a protection circuit is activated in the event of an abnormality, causing the switch circuit to stop operating, and that can suppress inrush current while suppressing heat generation and efficiency reduction during normal operation.

The power supply device of the present invention is a power supply device that supplies a DC voltage to an inductive load, and includes a DC source, a switch circuit having a plurality of switch elements that switches an input DC voltage from the DC source using the plurality of switch elements, a DC conversion circuit that converts the output voltage from the switch circuit into DC and supplies it to the inductive load, and an inrush current suppression circuit connected between the DC source and the switch circuit, and the inrush current suppression circuit is interposed in a high potential line that connects a high potential output terminal of the DC source and a high potential input terminal of the switch circuit. The power supply circuit includes a first diode having an anode connected to the high potential output terminal of the DC source, a resistor element having one end connected to the high potential line on the cathode side of the first diode, a capacitor having one end connected to the other end of the resistor element and the other end connected to a low potential line connecting the low potential output terminal of the DC source and the low potential input terminal of the switch circuit, and a short circuit means for short circuiting the resistor element when a voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds a predetermined value that is equal to or greater than 0V.

During power supply, in which the input DC voltage from the DC source is supplied to the inductive load via the switch circuit and the DC converter circuit, a forward current flows through the first diode, so that the voltage on the cathode side of the first diode is lower than the voltage on the anode side by the forward voltage. That is, the voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode is less than 0 V and is less than a predetermined value. Therefore, during power supply, the shorting means does not short-circuit the resistance element. Therefore, when the DC source is started, the charging current to the capacitor flows while being limited by the resistance element, so that the inrush current can be suppressed. Since the resistance element is connected in series with the capacitor, no current flows through the resistance element during normal operation after charging of the capacitor is completed. Therefore, power loss during normal operation in the resistance element can be avoided.

When the switch circuit stops operating due to the protection circuit being activated when an abnormality occurs, the energy stored in the inductive load is regenerated as an induced electromotive force, and a regenerative current flows from the output side to the input side of the switch circuit. This regenerative current flows in the opposite direction to the first diode, so it does not flow through the first diode, but flows into the capacitor via the resistance element. This causes the voltage on the cathode side of the first diode to rise. Then, when the voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds a predetermined value, the resistance element is short-circuited by the short-circuiting means. By short-circuiting the resistance element, it is possible to prevent the resistance element from hindering the absorption effect of the regenerative energy into the capacitor. In this way, the short-circuiting means shorts the resistance element only when the switch circuit stops operating due to an abnormality. Therefore, compared to when the resistance element is maintained in a short-circuited state during normal operation, it is possible to suppress the inrush current while suppressing heat generation and efficiency reduction.

In the power supply device described above, the short-circuiting means is a transistor connected in parallel with the resistive element, and the transistor has a first main electrode connected to the cathode side of the first diode, a second main electrode connected between the resistive element and the capacitor, and a control electrode conductively connected to the anode side of the first diode.

With this simple configuration, it is possible to realize a short-circuiting means that shorts the resistance element only when the operation of the switch circuit stops due to the occurrence of an abnormality.

Furthermore, in the above-mentioned power supply device, the inrush current suppression circuit further includes a second diode between the control electrode and the high potential output terminal of the DC source, the cathode side of which is conductively connected to the high potential output terminal of the DC source.

This configuration makes it possible to prevent current from flowing from the high-potential output terminal of the DC source to the control electrode of the transistor.

In addition, in the above-mentioned power supply device, the inrush current suppression circuit further includes a constant voltage diode between the control electrode and the anode side of the first diode, the cathode side of which is conductively connected to the control electrode.

With this configuration, the short-circuiting means can prevent the resistance element from being short-circuited until the voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds the Zener voltage of the constant-voltage diode, thereby suppressing malfunction of the short-circuiting means.

Furthermore, in the above-mentioned power supply device, the inrush current suppression circuit further includes a third diode in parallel with the resistive element, the anode side of which is connected to the one end of the capacitor.

With this configuration, after the regenerative current has stopped flowing, the abnormality is eliminated, and during normal operation when the switch circuit resumes operation and supplies power to the inductive load, the power stored in the capacitor can be smoothly discharged via the third diode.

In addition, in the above-mentioned power supply device, the switch circuit is configured to be able to switch the polarity of the DC voltage that is output.

This configuration is suitable for supplying DC voltage to an inductive load, such as a steering electromagnet, that requires the polarity of the supplied DC voltage to be switchable.

The present invention has the function of absorbing regenerative current from an inductive load that occurs when the switch circuit stops operating due to the protection circuit being activated in the event of an abnormality, and can suppress inrush current while suppressing heat generation and efficiency reduction during normal operation.

1 is a circuit diagram showing a configuration of a power supply device according to an embodiment of the present invention; 2A and 2B are diagrams showing the switch circuit of FIG. 1 , in which FIG. 2A shows a current flow in a first state under PWM control, and FIG. 2B shows a current flow in a second state under PWM control. FIG. 2 is a diagram showing the switch circuit of FIG. 1 , illustrating a state in which a regenerative current flows in from an inductive load. FIG. 13 is a diagram showing a switch circuit of a power supply device according to a first modified example. FIG. 13 is a diagram illustrating an inrush current suppression circuit of a power supply device according to a second modified example.

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

(Circuit configuration of power supply device 1)
First, the circuit configuration of a power supply device 1 according to this embodiment will be described with reference to Figures 1 to 3. The power supply device 1 of this embodiment supplies a DC voltage to a steering electromagnet 2 that corrects the trajectory of a beam of charged particles in a synchrotron (circular accelerator). The power supply device 1 has a pair of output terminals T13, T14 to which the steering electromagnet 2, which is an inductive load, is connected. The power supply device 1 also mainly includes a DC-DC converter 3, a switch circuit 4, a DC conversion circuit 5, an inrush current suppression circuit 6, and a control circuit 9.

The DC-DC converter 3 outputs a DC voltage. In other words, the DC-DC converter 3 corresponds to the DC source of the present invention. The DC-DC converter 3 of this embodiment is an insulated type. The high-potential input terminal T31 of the DC-DC converter 3 is connected to the input terminal T11, and the low-potential input terminal T32 is connected to the GND terminal T12. The DC-DC converter 3 receives a DC voltage applied between the input terminal T11 and the GND terminal T12. The DC-DC converter 3 boosts or lowers the input DC voltage and outputs it.

The switch circuit 4 receives the DC voltage output from the DC-DC converter 3. The high-potential input terminal T41 of the switch circuit 4 is connected to the high-potential output terminal T33 of the DC-DC converter 3 by a high-potential line 61. The low-potential input terminal T42 of the switch circuit 4 is connected to the low-potential output terminal T34 of the DC-DC converter 3 by a low-potential line 62.

The high-potential output terminal T43 of the switch circuit 4 is connected to the output terminal T13 by a wiring 81. A coil L1 is interposed in the wiring 81. The low-potential output terminal T44 of the switch circuit 4 is connected to the output terminal T14 by a wiring 82. The DC circuit 5 is connected between the output terminals T43, T44 and the output terminals T13, T14.

As shown in FIG. 2, the switch circuit 4 is a full bridge circuit in which four switch elements S1 to S4 are bridge-connected. The switch circuit 4 switches the input DC voltage from the DC-DC converter 3 using these switch elements S1 to S4. The switch circuit 4 is configured to be able to switch the polarity of the output DC voltage. The switch elements S1 to S4 are configured with semiconductor devices such as IGBTs and FETs. In this embodiment, the switch elements S1 to S4 are N-channel IGBTs. The four switch elements S1 to S4 are provided with freewheel diodes D1 to D4, respectively. Note that when the switch elements are FETs, the internal body diodes can be used as freewheel diodes.

One end of wire 71 is connected to high potential input terminal T41, and the other end branches into wires 73 and 74. The end of wire 73 opposite to wire 71 is connected to the collector of switch element S1. The end of wire 74 opposite to wire 71 is connected to the collector of switch element S3.

One end of wire 72 is connected to low-potential input terminal T42, and the other end branches into wires 75 and 76. The end of wire 75 opposite to wire 72 is connected to the emitter of switch element S2. The end of wire 76 opposite to wire 72 is connected to the emitter of switch element S4.

The emitter of switch element S1 and the collector of switch element S2 are connected by wiring 77. That is, switch element S1 and switch element S2 are connected in series. One end of wiring 79 is connected to the middle of wiring 77. The other end of wiring 79 is connected to high potential output terminal T43.

The emitter of switch element S3 and the collector of switch element S4 are connected by wiring 78. That is, switch element S3 and switch element S4 are connected in series. One end of wiring 80 is connected to the middle of wiring 78. The other end of wiring 80 is connected to low-potential output terminal T44.

As shown in FIG. 1, the DC circuit 5 is connected between a pair of output terminals T43, T44 of the switch circuit 4 and output terminals T13, T14 to which the steering electromagnet 2 is connected. The DC circuit 5 converts the output voltage from the switch circuit 4 into a DC voltage and supplies it to the steering electromagnet 2. The DC circuit 5 is an LC high-frequency filter made up of a coil L1 and a capacitor C2. The DC circuit 5 attenuates current ripples caused by the switching of the switch elements S1 to S4. In FIG. 1, the coil L1 constituting the DC circuit 5 is provided between the output terminal T43 and the output terminal T13. However, the coil L1 may be provided by being interposed in the wiring 82 connecting the output terminal T44 and the output terminal T14.

A capacitor C3 is disposed between the high potential line 61 and the low potential line 62. One end of a wiring 83 is connected to the high potential line 61, and the other end of the wiring 83 is connected to one end of the capacitor C3. One end of a wiring 84 is connected to the low potential line 62, and the other end of the wiring 84 is connected to the other end of the capacitor C3. The capacitor C3 can stabilize noise from the switch circuit 4.

The switch circuit 4 is controlled by a control circuit 9. The control circuit 9 performs PWM control on the switch elements S1 and S2 to adjust the amount of current output from the switch circuit 4. The control circuit 9 also performs on/off control on the switch elements S3 and S4 to switch the polarity of the current output from the switch circuit 4.

2(a) and 2(b), the switch element S3 is OFF and the switch element S4 is ON. At this time, the polarity of the current output from the switch circuit 4 is positive. In PWM control, the ON state (first state) shown in FIG. 2(a) and the OFF state (second state) shown in FIG. 2(b) are switched. In FIGS. 2(a) and 2(b), the direction of the current flow is indicated by a two-dot chain line arrow. As shown in FIG. 2(a), in the ON state, the switch element S1 is ON and the switch element S2 is OFF. As shown in FIG. 2(b), in the OFF state, the switch element S1 is OFF and the switch element S2 is ON. In PWM control, the amount of current output from the switch circuit 4 is adjusted by changing the time width (duty) of the ON state.

In addition, by turning switch element S3 ON and switch element S4 OFF, the polarity of the current output from switch circuit 4 can be made negative. In this case, in PWM control, turning switch element S1 OFF and switch element S2 ON results in the ON state (first state), and turning switch element S1 ON and switch element S2 OFF results in the OFF state (second state).

Now, referring to FIG. 3, we will explain the case where a protection circuit such as the output overcurrent protection circuit or overvoltage protection circuit of the switch circuit 4 is activated when an abnormality occurs and the operation of the switch circuit 4 stops. In FIG. 3, the direction of current flow is indicated by a two-dot chain line arrow. When the protection circuit is activated, all of the switch elements S1 to S4 are turned OFF. At this time, the energy stored in the steering electromagnet 2 is regenerated as an induced electromotive force. The regenerated current flows from the output side to the input side of the switch circuit 4 via the freewheel diodes D2 and D3 of the switch circuit 4, and flows into the capacitor C1, which will be described in detail later.

Returning to FIG. 1, the inrush current suppression circuit 6 is connected between the DC-DC converter 3 and the switch circuit 4. The inrush current suppression circuit 6 mainly includes a diode D5, a resistor element R1, a capacitor C1, a transistor Q, a constant voltage diode ZD, a diode D6, and a diode D7.

Diode D5 is inserted in the high potential line 61 that connects the high potential output terminal T33 of the DC-DC converter 3 and the high potential input terminal T41 of the switch circuit 4. The anode side of diode D5 is connected to the high potential output terminal T33 of the DC-DC converter 3. Diode D5 prevents the regenerative current from flowing into the high potential output terminal T33 of the DC-DC converter 3.

One end of the resistor element R1 is connected to the high potential line 61 on the cathode side of the diode D5. More specifically, one end of the resistor element R1 is connected to the other end of the wiring 92 that branches off from the high potential line 61 between the connection portion with the wiring 83 and the diode D5.

The positive electrode of capacitor C1 is connected to the other end of resistor element R1 by wiring 93. The negative electrode of capacitor C1 is connected to the low potential line 62.

Capacitor C1 has a capacitance that corresponds to the capacitance of steering electromagnet 2. When the operation of switch circuit 4 stops due to the occurrence of an abnormality, regenerative energy from steering electromagnet 2 can be stored in capacitor C1. The regenerative energy is also stored in capacitor C3. However, the capacitance of capacitor C1 is sufficiently larger than that of capacitor C3, and the regenerative energy is mainly stored in capacitor C1.

If the capacitance of capacitor C1 is large, when DC-DC converter 3 starts up, the charging current to capacitor C1 may become an inrush current, which may trip the overcurrent protection circuit of DC-DC converter 3. If the overcurrent protection method is a stopping operation such as an output shutdown stopping operation or an intermittent stopping operation, it may not be possible to start up properly. The inrush current suppression circuit 6 is a circuit that suppresses this inrush current.

Transistor Q is a PNP transistor connected in parallel with resistor R1. Transistor Q can short-circuit resistor R1. The emitter of transistor Q (corresponding to the "first main electrode" of the present invention) is connected to the cathode side of diode D5. The collector of transistor Q (corresponding to the "second main electrode" of the present invention) is connected between resistor R1 and capacitor C1. The base of transistor Q (corresponding to the "control electrode" of the present invention) is conductively connected to the anode side of diode D5 via base resistor R2, constant voltage diode ZD, and diode D6.

One end of wire 94 is connected to the middle of wire 92, and the other end is connected to the emitter of transistor Q. One end of wire 95 is connected to the middle of wire 93, and the other end is connected to the collector of transistor Q. One end of wire 96 is connected to a portion of high potential line 61 between high potential output terminal T33 of DC-DC converter 3 and diode D5, and the other end is connected to the base of transistor Q.

A base resistor R2 of transistor Q is interposed in wiring 96. A base-emitter resistor R3 of transistor Q is interposed in wiring 97, one end of which is connected to the portion of wiring 96 between the base of transistor Q and base resistor R2, and the other end of which is connected to the middle of wiring 94.

Diode D6 is disposed between the base of transistor Q and the high potential output terminal T33 of DC-DC converter 3. Diode D6 is disposed between the connection portion of wiring 96 with high potential line 61 and base resistor R2. The cathode side of diode D6 is conductively connected to the high potential output terminal T33 of DC-DC converter 3.

The constant voltage diode ZD is disposed between the base of the transistor Q and the anode side of the diode D5. The constant voltage diode ZD is disposed in the portion of the wiring 96 between the diode D6 and the base resistor R2. The cathode side of the constant voltage diode ZD is conductively connected to the base of the transistor Q via the base resistor R2.

Diode D7 is connected in parallel with resistor element R1. One end of diode D7 is connected to the middle of wiring 92, and the other end is disposed on wiring 98, which is connected to the middle of wiring 93. The anode side of diode D7 is connected to the positive electrode of capacitor C1.

(Operation of inrush current suppression circuit 6)
Next, the operation of the inrush current suppression circuit 6 will be described. First, consider the time of power supply, in which the DC voltage from the DC-DC converter 3 is output to the steering electromagnet 2 via the switch circuit 4 and the DC conversion circuit 5. During power supply, a forward current flows through the diode D5, so that the voltage V2 between the cathode side of the diode D5 and GND is lower than the voltage V1 on the anode side of the diode D5 by the amount of the forward voltage. In other words, the voltage applied to the base of the transistor Q is a positive voltage with respect to the emitter. Therefore, during power supply, the transistor Q is in an OFF state, and the resistor element R1 is not short-circuited by the transistor Q.

When the DC-DC converter 3 starts up, the charging current to the capacitor C1 flows while being limited by the resistance element R1, so the inrush current can be suppressed. Because the resistance element R1 is connected in series with the capacitor C1, no current flows through the resistance element R1 during normal operation after charging of the capacitor C1 is completed. Therefore, power loss during normal operation in the resistance element R1 can be avoided.

Next, consider the case where the switch circuit stops operating due to an abnormality. At this time, regenerative current from the steering electromagnet 2 flows from the output side to the input side of the switch circuit 4. Since this regenerative current flows in the reverse direction relative to diode D5, it does not flow through diode D5, but flows into capacitor C1 via resistance element R1. This causes the voltage V2 on the cathode side of diode D5 to rise. Then, when the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of diode D5 exceeds the Zener voltage Vz of the constant-voltage diode ZD, transistor Q switches from OFF to ON. When transistor Q turns ON, resistance element R1 is short-circuited by transistor Q.

In other words, when the voltage V1 on the anode side of diode D5, the voltage V2 on the cathode side of diode D5, and the Zener voltage Vz of constant-voltage diode ZD (0<Vz) satisfy the relationship V2-V1>Vz, transistor Q is turned ON and shorts out resistor element R1.

When transistor Q switches from OFF to ON, resistor element R1 is shorted, preventing resistor element R1 from impeding the effect of absorbing regenerative energy into capacitor C1.

After the regenerative current from the steering electromagnet 2 has stopped flowing, the charge stored in the capacitor C1 is smoothly discharged via the diode D7 during normal operation when the switch circuit 4 resumes operation and supplies power to the steering electromagnet 2.

(Features of the embodiment)
As described above, the power supply device 1 of this embodiment is a power supply device 1 that supplies a DC voltage to the steering electromagnet 2, which is an inductive load, and is equipped with a DC-DC converter 3, a switch circuit 4 having a plurality of switch elements S1 to S4 and switching an input DC voltage from the DC-DC converter 3 using the switch elements S1 to S4, a DC conversion circuit 5 that converts the output voltage from the switch circuit 4 into DC and supplies it to the steering electromagnet 2, and an inrush current suppression circuit 6 connected between the DC-DC converter 3 and the switch circuit 4. The inrush current suppression circuit 6 is disposed in a high potential line 61 connecting the high potential output terminal T33 of the DC-DC converter 3 and the high potential input terminal T41 of the switch circuit 4, and includes a diode D5 having an anode side connected to the high potential output terminal T33 of the DC-DC converter 3, a resistive element R1 having one end connected to the high potential line 61 on the cathode side of the diode D5, a capacitor C1 having one end connected to the other end of the resistive element R1 and the other end connected to a low potential line 62 connecting the low potential output terminal T34 of the DC-DC converter 3 and the low potential input terminal T42 of the switch circuit 4, and a transistor Q which shorts out the resistive element R1 when a voltage difference obtained by subtracting the anode side voltage V1 from the cathode side voltage V2 of the diode D5 exceeds a predetermined value (Zener voltage Vz) which is 0 V or more.

When power is being supplied, the voltage difference obtained by subtracting the anode side voltage V1 from the cathode side voltage V2 of diode D5 is less than a predetermined value (Zener voltage Vz). Therefore, when power is being supplied, transistor Q does not short-circuit resistor element R1. Therefore, when DC-DC converter 3 starts up, the charging current to capacitor C1 flows while being limited by resistor element R1, so inrush current can be suppressed. Because resistor element R1 is connected in series with capacitor C1, no current flows through resistor element R1 during normal operation after charging of capacitor C1 is completed. Therefore, power loss during normal operation in resistor element R1 can be avoided.

In addition, when the protection circuit is activated in the event of an abnormality, the regenerative current from the steering electromagnet 2 that is generated when the operation of the switch circuit 4 stops flows in the reverse direction relative to the diode D5, so it does not flow through the D5 diode, but flows into the capacitor C1 via the resistance element R1. This causes the voltage V2 on the cathode side of the diode D5 to rise. Then, when the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of the diode D5 exceeds a predetermined value (Zener voltage Vz), the resistance element R1 is short-circuited by the transistor Q. By shorting the resistance element R1, it is possible to prevent the resistance element R1 from hindering the absorption effect of the regenerative energy into the capacitor C1. In this way, the transistor Q shorts the resistance element R1 only when the operation of the switch circuit stops due to the occurrence of an abnormality. Therefore, compared to when the resistance element R1 is maintained in a shorted state during normal operation, it is possible to suppress the inrush current while suppressing heat generation and efficiency reduction.

In the power supply device 1 of this embodiment, the transistor Q is a PNP transistor connected in parallel with the resistance element R1, with its emitter connected to the cathode side of the diode D5, its collector connected between the resistance element R1 and the capacitor C1, and its base conductively connected to the anode side of the diode D5. With this simple configuration, it is possible to realize a short-circuiting means that shorts the resistance element R1 only when the operation of the switch circuit 4 stops due to the occurrence of an abnormality.

In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a diode D6 between the base of the transistor Q and the high potential output terminal T33 of the DC-DC converter 3, the cathode of which is conductively connected to the high potential output terminal T33 of the DC-DC converter 3. This configuration makes it possible to prevent current from flowing from the high potential output terminal T33 of the DC-DC converter 3 toward the base of the transistor Q.

In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a constant voltage diode ZD, the cathode of which is conductively connected to the base of the transistor Q, between the base of the transistor Q and the anode of the diode D5. With this configuration, the transistor Q can prevent the resistor element R1 from being short-circuited until the voltage difference obtained by subtracting the anode voltage V1 from the cathode voltage V2 of the diode D5 exceeds the Zener voltage Vz of the constant voltage diode ZD, thereby suppressing malfunction of the transistor Q.

In the power supply device 1 of this embodiment, the inrush current suppression circuit 6 further includes a diode D7, the anode of which is connected to the positive electrode of the capacitor C1, in parallel with the resistive element R1. With this configuration, after the regenerative current has stopped flowing, the abnormality is eliminated, and the switch circuit 4 resumes operation to supply power to the steering electromagnet 2. During normal operation, the power stored in the capacitor C1 can be smoothly discharged via the diode D7.

In the power supply device 1 of this embodiment, the switch circuit 4 is configured to be able to switch the polarity of the DC voltage that is output. This configuration is suitable for supplying a DC voltage to an inductive load that requires the polarity of the supplied DC voltage to be switchable, such as the steering electromagnet 2.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments. The scope of the present invention is indicated by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

In the above embodiment, the case where the polarity of the DC voltage output by the switch circuit 4 is switchable has been described, but the present invention is not limited to this. That is, as shown in FIG. 4, the switch circuit 4A of the power supply device according to the first modification of this embodiment has switch elements S1, S2, S4 and free-wheeling diodes D1, D2, D4 similar to those of the switch circuit 4. In the switch circuit 4A, the end of the wiring 74 opposite to the wiring 71 side is connected to the collector of the switch element S4. A diode D13 is also interposed in the wiring 74. The cathode of the diode D13 is connected to the high-potential input terminal T41.

In the switch circuit 4A, the control circuit 9 performs PWM control on the switch elements S1 and S2, and the amount of current output from the switch circuit 4A can be adjusted. In the switch circuit 4A, the regenerative current from the steering electromagnet 2 also flows from the output side to the input side of the switch circuit 4A via the freewheel diode D2 and diode D13 of the switch circuit 4A, and then flows into the capacitor C1.

In the above embodiment, a PNP transistor Q connected in parallel with the resistive element R1 is used as the short-circuiting means for short-circuiting the resistive element R1, but this is not limited to the above. That is, as shown in FIG. 5, in the inrush current suppression circuit 6A of the power supply device according to the second modified example of this embodiment, a Pch FET transistor Q0 connected in parallel with the resistive element R1 is used as the short-circuiting means.

The transistor Q0 has a first main electrode (source) connected to the cathode side of the diode D5, a second main electrode (drain) connected between the resistor element R1 and the capacitor C1, and a control electrode (gate) conductively connected to the anode side of the diode D5.

When the transistor Q0 is used as the short-circuiting means, similar to the transistor Q, the resistance element R1 can be short-circuited when the voltage difference obtained by subtracting the anode side voltage V1 from the cathode side voltage V2 of the diode D5 exceeds a predetermined value (Zener voltage Vz) that is 0 V or more. Therefore, with a simple configuration, it is possible to realize a short-circuiting means that shorts the resistance element R1 only when the operation of the switch circuit 4 stops due to the occurrence of an abnormality.

In addition, in the above embodiment, a case has been described in which a diode D6 is disposed between the base of the transistor Q and the high potential output terminal T33 of the DC-DC converter 3, but the diode D6 may be omitted.

In addition, in the above embodiment, the constant voltage diode ZD is disposed between the diode D6 and the base resistor R2, but this is not limited to the above. The constant voltage diode ZD only needs to be disposed between the base of the transistor Q and the anode side of the diode D5. The constant voltage diode ZD may also be omitted. If the constant voltage diode ZD is not disposed, the transistor Q shorts the resistance element R1 when the voltage difference obtained by subtracting the voltage V1 on the anode side from the voltage V2 on the cathode side of the diode D5 exceeds 0 V, i.e., when V2>V1.

In addition, in the above embodiment, a case has been described in which a diode D7 is connected in parallel with the resistive element R1, but the diode D7 may be omitted.

In the above embodiment, the DC source that outputs the DC voltage is an insulated DC-DC converter 3, but this is not limited to this. In other words, the DC source may be a non-insulated DC-DC converter. Furthermore, the DC source may be a battery (lithium ion battery, nickel metal hydride battery, etc.), a battery (storage battery), a solar cell, a fuel cell, an AC-DC converter, etc.

In addition, in the above embodiment, the load is the steering electromagnet 2, but this is not limited to the case. The present invention is applicable to any power supply device that supplies a DC voltage to an inductive load.

1 Power supply unit 2 Steering electromagnet (inductive load)
3 DC-DC converter (DC source)
4 Switch circuit 5 DC circuit 6 Inrush current suppression circuit 61 High potential line 62 Low potential line C1 Capacitor D1 to D4 Freewheeling diodes D5 Diode (first diode)
D6 Diode (second diode)
D7 Diode (third diode)
Q Transistor (short circuit means, PNP transistor)
Q0 Transistor (short circuit means, Pch FET)
R1 Resistance element S1 to S4 Switching elements T33 High potential output terminal T34 Low potential output terminal T41 High potential input terminal T42 Low potential input terminal ZD Constant voltage diode

Claims (6)

A power supply device that supplies a DC voltage to an inductive load,
A direct current source;
a switch circuit having a plurality of switch elements for switching an input DC voltage from the DC source by the plurality of switch elements;
a DC converter circuit that converts an output voltage from the switch circuit into a DC voltage and supplies the DC voltage to the inductive load;
an inrush current suppression circuit connected between the DC source and the switch circuit;
Equipped with
The inrush current suppression circuit includes:
a first diode, which is interposed in a high potential line connecting a high potential output terminal of the DC source and a high potential input terminal of the switch circuit, and has an anode side connected to the high potential output terminal of the DC source;
a resistor element having one end connected to the high potential line on the cathode side of the first diode;
a capacitor having one end connected to the other end of the resistor element and the other end connected to a low potential line connecting a low potential output terminal of the DC source and a low potential input terminal of the switch circuit;
and a short-circuiting means for short-circuiting the resistance element when a voltage difference obtained by subtracting the voltage on the anode side from the voltage on the cathode side of the first diode exceeds a predetermined value that is 0 V or more. The short circuit means is a transistor connected in parallel with the resistance element,
2. The power supply device according to claim 1, wherein the transistor has a first main electrode connected to the cathode side of the first diode, a second main electrode connected between the resistance element and the capacitor, and a control electrode conductively connected to the anode side of the first diode. The inrush current suppression circuit includes:
3. The power supply device according to claim 2, further comprising a second diode between the control electrode and the high potential output terminal of the DC source, the cathode side of which is conductively connected to the high potential output terminal of the DC source. The inrush current suppression circuit includes:
3. The power supply device according to claim 2, further comprising a constant voltage diode between the control electrode and the anode side of the first diode, the cathode side of which is conductively connected to the control electrode. The inrush current suppression circuit includes:
2. The power supply device according to claim 1, further comprising a third diode connected in parallel with the resistance element, the third diode having an anode connected to the one end of the capacitor. The power supply device according to any one of claims 1 to 5, characterized in that the switch circuit is configured to be able to switch the polarity of the DC voltage supplied to the inductive load.

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