Power supply device

Abstract

To provide a technology for weakening (reducing) the electric field strength in a secondary winding of an isolated DC-DC converter without disassembling or modifying an isolated DC-DC converter in a power supply device using an isolated DC-DC converter purchased as a component.SOLUTION: A power supply device includes an isolated DC-DC converter with an internal transformer, and a conductor that is external to the isolated DC-DC converter and electrically connected to the output terminal of the isolated DC-DC converter, and the conductor is arranged in a direction perpendicular to a direction from the primary side to the secondary side of the transformer when viewed from a secondary winding of the transformer.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power supply device.

Background Art

[0002] In a plasma processing apparatus used in a process for manufacturing a semiconductor wafer or a liquid crystal substrate, for example, a power supply device for generating a high voltage is provided, such as a pulse power supply device for generating a pulsed voltage (pulse voltage) (see, for example, Patent Document 1). In the power supply device as described above, a DC voltage supplied from a DC power supply is converted into a pulse voltage by a switching circuit and output. In recent years, an increase in output has been demanded. For example, a high voltage pulse having an absolute value of 10 kV or more is required. The potential of the high voltage pulse may be + (plus) or - (minus). In such a power supply device, the switching circuit includes a plurality of switching elements. A DC voltage (for example, a voltage having a potential difference of 24 V) is supplied from an isolation type DC-DC converter to a drive circuit for driving each switching element. The reason why an isolation type DC-DC converter is used is that since the voltage switched by the switching element is a high voltage, the primary side (input side) and the secondary side (output side) are insulated by the built-in transformer. When the voltage value of the high voltage pulse is large, the isolation type DC-DC converter may be configured by a series connection of a plurality of stages (for example, three stages).

[0003] Now, as is well known, there is a stray capacitance between the primary winding and the secondary winding of a transformer. The presence of the stray capacitance indicates that the primary winding and the secondary winding of the transformer function as electrodes of a capacitor, respectively. Therefore, when a voltage is applied to the transformer built into an isolated DC-DC converter, the amount of charge between the primary and secondary windings of the transformer increases or decreases in proportion to the magnitude of the applied voltage. There is also a relationship in which the electric field strength increases or decreases in accordance with the increase or decrease in the amount of charge. For this reason, when the voltage applied to the transformer increases, the electric field strength acting on the primary and secondary windings becomes stronger (larger). When the electric field strength increases, dielectric loss near the windings (for example, the molded part covering the windings) increases, and the amount of heat generated increases. For this reason, in a transformer, dielectric loss is greater on the secondary winding side than on the primary winding side, and the amount of heat generated is greater there. In addition, when the electric field strength increases, corona discharge is more likely to occur.

[0004] Given this relationship, when the secondary potential (output potential) of an isolated DC-DC converter becomes high (absolute value of 10kV or more), the electric field strength in the secondary winding of the transformer built into the isolated DC-DC converter also increases, and consequently, the dielectric loss also increases. Furthermore, corona discharge becomes more likely to occur.

[0005] One possible solution to this problem is to reduce the electric field strength. From this perspective, as shown in Patent Document 2, a technique has been proposed to reduce the electric field strength by providing a corona ring to the transformer, but this requires directly providing the corona ring to the transformer. The technique of providing a corona ring to the transformer is not applicable when purchasing an isolated DC-DC converter as a component and combining it with other components to manufacture a power supply. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-125729 [Patent Document 2] Japanese Patent Publication No. 2004-335696 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of the above problems, and aims to provide a technology for weakening (reducing) the electric field strength in the secondary winding of an isolated DC-DC converter in a power supply device using an isolated DC-DC converter purchased as a component, without disassembling or modifying the isolated DC-DC converter. [Means for solving the problem]

[0008] The power supply device according to this embodiment comprises an isolated DC-DC converter with a transformer inside, and a conductor located outside the isolated DC-DC converter and electrically connected to the output terminal of the isolated DC-DC converter, wherein the conductor is arranged in a direction perpendicular to the direction from the primary side to the secondary side of the transformer, as viewed from the secondary winding of the transformer.

[0009] In the power supply device according to this embodiment, the isolated DC-DC converter and the conductor are provided on a circuit board. In the power supply device according to this embodiment, the conductor is a metal spacer, a plate-shaped conductor, or a conductor arranged to surround the secondary winding of the transformer. In the power supply device according to this embodiment, the conductor is composed of a first conductor arranged to surround the secondary winding of the transformer and a second conductor electrically connected to the first conductor. In the power supply device according to this embodiment, the isolated DC-DC converter is part of a plurality of DC-DC converters connected in series, and is an isolated DC-DC converter in which the absolute value of the secondary potential is equal to or greater than the absolute value of a predetermined potential. [Effects of the Invention]

[0010] According to the present invention, in a power supply device using an isolated DC-DC converter purchased as a component, the electric field strength in the secondary winding of the isolated DC-DC converter can be weakened (reduced) without disassembling or modifying the isolated DC-DC converter. Moreover, since the conductor is placed outside the isolated DC-DC converter, the countermeasure can be easily implemented. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows an example of the layout of an isolated DC-DC converter (schematic plan view). [Figure 2] Figure 2 shows the equivalent circuit when the primary and secondary windings of a transformer are considered as the electrodes of a capacitor. [Figure 3] Figure 3 shows an example of the placement of conductors for external electrodes. [Figure 4] Figure 4 shows an example of the configuration of an external electrode conductor that functions as an external electrode (cross-sectional view as seen from the direction of the arrow in Figure 3). [Figure 5] Figure 5 shows the electrode area for each configuration example shown in Figure 4. [Figure 6] Figure 6 shows the simulation results. [Figure 7] Figure 7 shows the experimental results. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the power supply device according to the present invention will be described with reference to the drawings. However, the present invention is not limited by these embodiments. In the following embodiments, parts with the same reference numerals are considered equivalent, and redundant explanations will be omitted as appropriate.

[0013] FIG. 1 is a diagram showing an arrangement example (schematic plan view) of three isolated DC-DC converters (the first-stage isolated DC-DC converter 11, the second-stage isolated DC-DC converter 12, and the third-stage isolated DC-DC converter 13) in a power supply device. Hereinafter, for simplicity of explanation, two directions orthogonal to each other in the horizontal plane are defined as the X-axis and the Y-axis, and the vertical direction is defined as the Z-axis. FIG. 1 shows a state of looking down on a circuit board 15 in the power supply device along the vertical direction. In the present embodiment, three isolated DC-DC converters each having a transformer 111 inside are connected in series, for example, as shown in FIG. 1, between an input terminal 17 and an output terminal 19 on the circuit board 15.

[0014] The potential of the output terminal 19 may be + (plus) or - (minus). Hereinafter, an example in the case where the potential of the output terminal 19 is + (plus) will be described. The potential of the input terminal 17 is a potential with a predetermined potential difference (for example, +24V) with respect to the ground (0V) of a power supply device such as a pulse power supply device. The potential of the output terminal 19 is a potential with a predetermined potential difference (for example, +24V) with respect to the output potential (+12 kV) of a power supply device such as a pulse power supply device. That is, the potential difference as seen from the ground (potential 0V) of the input terminal 17 is +24V. Also, the potential as seen from the ground of the output terminal 19 is +12024V.

[0015] Therefore, in the first-stage isolated DC-DC converter 11, the potential on the primary side is at most 24V (absolute value), and the potential on the secondary side is at most 4024V (absolute value). Also, in the second-stage isolated DC-DC converter 12, the potential on the primary side is at most 4024V (absolute value), and the potential on the secondary side is at most 8024V (absolute value). Also, in the third-stage isolated DC-DC converter 13, the potential on the primary side is at most 8024V (absolute value), and the potential on the secondary side is at most 12024V (absolute value).

[0016] Note that in FIG. 1, since the transformer 111 is inside each of the three isolated DC-DC converters 11, 12, and 13, it is represented by a dotted line. Also, since the pattern wiring 21 on the circuit board 15 is formed on the back surface of the circuit board 15, it is represented by a dotted line. Of course, the pattern wiring 21 may be formed on the front surface of the circuit board 15. Also, the wiring for electrically connecting a plurality of isolated DC-DC converters is not limited to the pattern wiring 21.

[0017] In addition to the transformer 111, the isolated DC-DC converter has components and terminals for voltage conversion, etc., but illustration thereof is omitted in FIG. 1.

[0018] Also, FIG. 1 is merely an example, and the arrangement of a plurality of isolated DC-DC converters is not limited thereto. For example, a plurality of isolated DC-DC converters may be arranged in a straight line.

[0019] FIG. 2 is a diagram showing an example of an equivalent circuit when the primary winding and the secondary winding of the transformer 111 are regarded as the electrodes of a capacitor with respect to FIG. 1. In FIG. 2, in order to clarify the relationship with FIG. 1, various components on the circuit board 15 are also shown. The 4 kV arrows shown near the first-stage isolated DC-DC converter 11, the second-stage isolated DC-DC converter 12, and the third-stage isolated DC-DC converter 13 in FIG. 2 indicate that a 4 kV potential difference has occurred between the primary side and the secondary side of each isolated DC-DC converter. <L

[0020] As is well known, there is a stray capacitance between the primary winding and the secondary winding of the transformer 111. The stray capacitance indicates that the primary winding and the secondary winding of the transformer 111 function as the electrodes of a capacitor, respectively. Therefore, when the primary winding and the secondary winding of the transformer 111 built in the isolated DC-DC converter are regarded as the electrodes of a capacitor, FIG. 1 becomes an equivalent circuit as shown in FIG. 2.

[0021] Of course, Figure 2 focuses on the fact that the primary and secondary windings of transformer 111 function as electrodes for a capacitor, and visualizes only that aspect; therefore, diagrams of the configuration for voltage conversion and other related components are omitted.

[0022] Figure 3 is a diagram illustrating an example of the arrangement of an external electrode conductor (hereinafter referred to as the external electrode conductor) 3 arranged on the circuit board 15 according to an embodiment. Looking from the secondary winding of the transformer 111 of the third (final) isolated DC-DC converter 13 shown in Figure 2, the conductor (hereinafter referred to as the external electrode conductor 3) is arranged on the circuit board 15 in a direction (Y direction) perpendicular to the direction (X direction) from the primary side to the secondary side (X direction) of the transformer 111. This external electrode conductor 3 is, for example, electrically connected to the output terminal 23 of the isolated DC-DC converter 13 outside the isolated DC-DC converter.

[0023] In other words, the output terminal 19 of the isolated DC-DC converter and the external electrode conductor 3 only need to be electrically connected. For example, the external electrode conductor 3 added to the circuit board 15 in Figures 1 and 2 may be electrically connected via the pattern wiring 21 between the third stage isolated DC-DC converter 13 and the output terminal 19, as shown in Figure 3. By creating a pattern wiring 21 on the circuit board 15 to connect the output terminal 19 of the isolated DC-DC converter and the conductor (external electrode conductor) 3, the isolated DC-DC converter and the conductor 3 can be provided on the circuit board 15, and the conductor 3 can be easily attached to the circuit board 15.

[0024] The external electrode conductor 3 described above will be explained below.

[0025] When a voltage is applied to the transformer 111 built into an isolated DC-DC converter, the amount of charge between the primary and secondary sides of the transformer 111 increases or decreases in proportion to the magnitude of the applied voltage. Furthermore, since the electric field strength increases or decreases in accordance with the increase or decrease in the amount of charge, as the voltage applied to the transformer 111 increases, the electric field strength acting on the primary and secondary windings becomes stronger (larger). When the electric field strength increases, dielectric loss near the windings (for example, the molded part covering the windings) increases, and the amount of heat generated increases. Therefore, in the transformer 111, the dielectric loss is greater on the secondary winding side than on the primary winding side, and the amount of heat generated is greater there. In addition, when the electric field strength increases, corona discharge is more likely to occur.

[0026] Therefore, by providing the external electrode conductor 3 as described above, the primary winding of the transformer 111 functions as one electrode of the capacitor (hereinafter referred to as the primary electrode), and the external electrode conductor 3 functions together with the secondary winding of the transformer 111 as the other electrode of the capacitor (hereinafter referred to as the enlarged secondary electrode). This makes it possible to reduce dielectric loss in the secondary winding. In this embodiment, without the external electrode conductor 3, the secondary winding of the transformer 111 functions as the other electrode of the capacitor (hereinafter referred to as the normal secondary electrode). Therefore, the external electrode conductor 3 can also be considered an external electrode attached to the normal secondary electrode.

[0027] Here, since the external electrode conductor 3 is placed outside the insulated DC-DC converter, the enlarged secondary electrode has a larger area than the normal secondary electrode. Therefore, the charge is more dispersed in the enlarged secondary electrode than in the normal secondary electrode, and the electric field strength in the secondary winding in the case of the enlarged secondary electrode is weaker (smaller) than the electric field strength in the secondary winding in the case of the normal secondary electrode. Therefore, by implementing the measures of this embodiment, the electric field strength in the secondary winding can be weakened (reduced). Furthermore, since the external electrode conductor 3 is placed outside the isolated DC-DC converter, there is no need to disassemble or modify the isolated DC-DC converter purchased as a component, making it easy to implement countermeasures.

[0028] The external electrode conductor 3 will be described in detail below using Figures 4 and 5. Figure 4 is a schematic diagram showing several configuration examples of the external electrode conductor 3 that functions as an external electrode 55. Specifically, Figure 4 shows several cross-sections of the external electrode conductor, including an example of a cross-section of the external electrode conductor 3 viewed from the direction of the X axis in Figure 3 (the direction of the arrow shown in Figure 3) (cross-sectional view in the direction of arrow AA). In addition, Figure 4 also shows a cross-section (a) when the external electrode conductor is not mounted, as an example of comparison with the cross-section of the external electrode conductor 3. Furthermore, in Figure 4, for the sake of explanation, the thickness of the pattern wiring 21 is shown as being thicker than the thickness of the circuit board 15. That is, in reality, the thickness of the pattern wiring 21 relative to the thickness of the circuit board 15 is thinner than shown in Figure 4. Figure 5 shows an example of an electrode area exceeding that of each configuration example shown in Figure 4.

[0029] The following describes the six configuration examples (a), (b), (c), (d), (e), and (f) shown in Figures 4 and 5. Note that the configuration and arrangement of the external electrode conductor 3 shown in Figures 4 and 5 are examples only and are not limited to these; various omissions, substitutions, and modifications can be made.

[0030] Figures 4 and 5(a) show a state in which the external electrode conductor 3 is not installed on the circuit board 15 (hereinafter referred to as "no countermeasures"), that is, a state in which countermeasures against corona discharge and the like have not been implemented. As shown in Figures 4 and 5 (a) without countermeasures, the third-stage isolated DC-DC converter 13 is electrically connected to the pattern wiring 21, for example, via a through-hole 191.

[0031] Figures 4 and 5(b) show a state in which a rectangular external electrode conductor 31 is installed on the circuit board 15 (hereinafter referred to as the pseudo-corona ring installation). The pseudo-corona ring 31 in Figure 4 is an external electrode conductor arranged to surround the secondary winding of the transformer 111. The external electrode conductor 31 in the pseudo-corona ring (b) of Figure 4 is not the corona ring itself, and is therefore referred to as the "pseudo-corona ring" below. The pseudo-corona ring 31 only needs to be an external electrode conductor arranged to surround the secondary winding of the transformer 111. For this reason, the pseudo-corona ring 31 does not have to be composed of a single material. For example, the pseudo-corona ring 31 may be constructed by bending a long, narrow copper plate into a rectangular shape, or it may be composed of a long, narrow copper plate 324 and a metal spacer 32. In addition, the pattern wiring 21 of the circuit board 15 may be used as part of the pseudo-corona ring 31.

[0032] As shown in the pseudo-corona ring installation (b) in Figures 4 and 5, the pseudo-corona ring 31 is electrically connected, for example, to the pattern wiring 21 on the output terminal 19 side of the third-stage isolated DC-DC converter 13 via a screw 311. Note that the connection between the pseudo-corona ring 31 and the pattern wiring 21 is not limited to a screw 311, but may also be electrically connected via, for example, a through-hole and solder. As a result, the potential of the pseudo-corona ring 31 is the same as that of the output terminal 19.

[0033] Figures 4 and 5(c) show a state in which a rod-shaped external electrode conductor (hereinafter referred to as a metal spacer) 32 is installed on the circuit board 15 (hereinafter referred to as metal spacer installation). A screw 321 is provided at the end of the metal spacer 32. Therefore, if the circuit board 15 has screw holes, the metal spacer 32 can be easily removed from the circuit board 15. In this case, the number of metal spacers 32 installed on the circuit board 15 can be easily adjusted according to the number of screw holes. By providing metal spacers 32 of various lengths, the area of ​​the external electrode 55 can be easily adjusted. It is also possible to use an external electrode conductor similar to the metal spacer 32 (e.g., one without screws) as the external electrode conductor. If the metal spacer 32 does not have a screw 321, the metal spacer 32 without a screw 321 may be fixed to the pattern wiring 21 of the circuit board 15 via a through-hole or the like by soldering. As a result, the potential of the metal spacer 32 is the same as that of the output terminal 19.

[0034] Figures 4 and 5(d) show a state in which a pseudo-corona ring and a metal spacer 32 are installed on the circuit board 15 as conductors for external electrodes (hereinafter referred to as pseudo-corona ring + metal spacer). In the pseudo-corona ring + metal spacer (d) shown in Figures 4 and 5, a pseudo-corona ring is formed by electrically connecting two metal spacers 323 and a copper plate 324 that are close to the third-stage isolated DC-DC converter 13, for example, with screws (311, 321). In addition, the copper plate 324 is also electrically connected to the metal spacer 32 furthest from the third-stage isolated DC-DC converter 13, for example, with screws. The combination of the pseudo-corona ring 31 and the metal spacer 32 allows for an increase in the electrode area compared to the pseudo-corona ring 31 alone. As described above, the metal spacer 323 can be utilized as part of the pseudo-corona ring, as shown in pseudo-corona ring + metal spacer (d).

[0035] Figures 4 and 5(e) show a state in which a pseudo-corona ring 31 and a plate-shaped conductor 33 are installed on the circuit board 15 as external electrode conductors (hereinafter referred to as pseudo-corona ring + plate-shaped conductor). With this configuration example, the electrode area can be increased compared to using only the pseudo-corona ring 31. In this configuration example, it is preferable that the pseudo-corona ring 31 and the added plate-shaped conductor 33 are in contact. However, the pseudo-corona ring 31 and the plate-shaped conductor 33 may not be in contact.

[0036] As shown in the pseudo-corona ring + plate-shaped conductor (e) in Figures 4 and 5, the plate-shaped conductor 33 is electrically connected, for example, via a screw 331 to the pattern wiring 21 on the output terminal 19 side of the third-stage isolated DC-DC converter 13. Therefore, the potential of the plate-shaped conductor 33 is the same as that of the output terminal 19. Furthermore, the connection between the plate-shaped conductor 33 and the pattern wiring 21 is not limited to screws 331; for example, they may be electrically connected via through-holes and solder. As a result, the potential of the plate-shaped conductor 33 will be the same as that of the output terminal 19. Alternatively, the pseudo-corona ring and the plate-shaped conductor 33 may be connected by solder or the like. In this case, the potential of the plate-shaped conductor 33 will be the same as that of the output terminal 19 without using screws 331 or the like.

[0037] Figures 4 and 5(f) show a state in which a plate-shaped conductor 33 is installed on the circuit board 15 as an external electrode conductor (hereinafter referred to as plate-shaped conductor installation). As shown in this example configuration, it is also possible to use a plate-shaped conductor 33 instead of a metal spacer 32.

[0038] As described above, the external electrode conductor 3 functions as an external electrode 55 and, together with the normal secondary electrode 53 in the transformer 111, functions as an enlarged secondary electrode 51. In other words, the external electrode conductor 3 enlarges the area of ​​the electrode.

[0039] Figure 5 shows the enlarged state of the electrode. Figure 5 illustrates the normal secondary electrode 53 and the external electrode 55, which function as the enlarged secondary electrode 51, from the direction of the arrow in Figure 3. In other words, the parts shown in Figure 5, except for the case without countermeasures (a) in Figure 5, represent the area of ​​the enlarged secondary electrode 51. Note that the primary electrode and the secondary electrode 53 are located opposite each other, and the area of ​​the primary electrode and the area of ​​the secondary electrode 53 are the same. Therefore, in Figure 5, the primary electrode is hidden by the secondary electrode 53 and is not visible. Also, in Figure 5, the output terminal 19 and the screws 321 of the metal spacer 32 are omitted.

[0040] As can be seen from Figure 5, by providing the external electrode conductor 3, the electrode area in this embodiment is increased compared to the case where only the secondary winding of the transformer 111 is used (usually only the secondary side electrode 53). In other words, since charge can be dispersed more effectively than in the case where only the secondary side electrode 53 is used, the electric field strength can be weakened (reduced) according to this embodiment.

[0041] For example, in Figure 5, under the cases of no countermeasures (a), pseudo-corona ring installation (b), metal spacer installation (c), pseudo-corona ring + metal spacer (d), and pseudo-corona ring + plate-shaped conductor (e), the area of ​​the pseudo-electrode increases in the order of no countermeasures (a), pseudo-corona ring installation (b), metal spacer installation (c), pseudo-corona ring + metal spacer (d), and pseudo-corona ring + plate-shaped conductor (e).

[0042] The simulation results of the electric field strength according to this embodiment will be explained below with reference to Figure 6. Figure 6 is a diagram showing an example of the simulation results according to this embodiment.

[0043] Figure 6 shows the simulation results of the electric field strength when the equivalent circuit shown in Figure 2 is assumed, and four conductors are arranged in a line along the X direction at regular intervals. A two-dimensional simulator was used for the simulation. Although the simulation results differ from the actual structure of transformer 111, it is possible to understand the degree of the electric field strength at the electrodes of the opposing capacitors. In the simulation shown in Figure 6, it is assumed that three (three-stage) isolated DC-DC converters are electrically connected in series between the input terminal 17 and the output terminal 19.

[0044] Figure 6(A) shows the simulation results when the four conductors are the same size (hereinafter referred to as the same-size simulation results). Furthermore, Figure 6(B) shows the simulation results when the size of the last conductor 14 (i.e., the one closest to the output terminal 19) is wider (approximately twice as wide) than the other conductors (hereinafter referred to as the "wide simulation results" for the last conductor).

[0045] As shown in Figure 6, the simulation results for the same size (A) and the landscape simulation results (B), the four conductors are subjected to potentials of 0kV, 4kV, 8kV, and 12kV, respectively. Furthermore, D1, D2, D3, D4, D5, and D6 shown in Figure 6 represent linear distances along the X direction, and correspond to the following positions with respect to the isolated DC-DC converter.

[0046] D1: Position corresponding to the primary electrode in the first stage isolated DC-DC converter 11. D2: Position corresponding to the secondary electrode in the first stage isolated DC-DC converter 11. D3: Position corresponding to the primary electrode in the second stage isolated DC-DC converter 12. D4: Position corresponding to the secondary electrode in the second-stage isolated DC-DC converter 12. D5: Position corresponding to the primary side electrode in the third stage isolated DC-DC converter 13. D6: Position corresponding to the secondary electrode in the third stage isolated DC-DC converter 13.

[0047] The graph (C) in Figure 6, which shows the simulation results, graphs the same-size simulation results (A) and the horizontal simulation results (B) for the position along axis SP in the X direction shown in Figure 6. The origin in graph (C) is the reference position on axis SP, which corresponds to a position located a predetermined distance from position D1 along the -X direction. Note that the electric field strength in the simulation result graph (C), which shows the change in electric field strength with respect to position, is the electric field strength at a position slightly offset from the center in the left-right direction (Y direction in Figure 6) of the conductor, as shown in Figure 6.

[0048] In graph (C) showing the simulation results in Figure 6, for the same-size simulation result (A), the electric field strength increases as the potential applied to the conductor increases (i.e., as the position moves away from the origin). For example, in graph (C), the electric field strength at position D6, which corresponds to the secondary electrode of the third-stage isolated DC-DC converter 13, is considerably larger than the electric field strength at position D1, which corresponds to the primary electrode of the first-stage isolated DC-DC converter 11. On the other hand, in the graph (C) showing the simulation results in Figure 6, in the case of the elongated simulation result (B), the fourth conductor 14 is elongated horizontally, so the charge is dispersed. Therefore, compared to the simulation result of the same size (A), the electric field strength of the elongated simulation result (B) is weaker (smaller), especially at position D6, which corresponds to the secondary electrode of the third-stage isolated DC-DC converter 13.

[0049] Therefore, the simulation results confirmed that the electric field strength can be reduced in the power supply unit by adding an external electrode using the external electrode conductor 3.

[0050] The experimental results related to this embodiment will be described below with reference to Figure 7. Figure 7 is a diagram showing an example of the experimental results related to this embodiment.

[0051] Figure 7 shows the results of temperature measurements using actual samples for the patterns of the external electrode conductor for the following configurations in Figures 4 and 5: no countermeasures (a), pseudo-corona ring installation (b) metal spacer installation (c), pseudo-corona ring + metal spacer (d), and pseudo-corona ring + plate-shaped conductor (e).

[0052] As shown in Figure 7, in the cases of no countermeasures (a), pseudo-corona ring installation (b), metal spacer installation (c), pseudo-corona ring + metal spacer (d), and pseudo-corona ring + plate-shaped conductor (e), it was confirmed that the temperature of the third-stage isolated DC-DC converter 13 decreased in the following order: no countermeasures (a): approximately 109 degrees, pseudo-corona ring installation (b): approximately 87 degrees, metal spacer installation (c): approximately 77 degrees, pseudo-corona ring + metal spacer (d): approximately 74 degrees, and pseudo-corona ring + plate-shaped conductor (e): approximately 72 degrees. In other words, it was confirmed that the temperature suppression was greater as the area of ​​the external electrode 55 increased. Furthermore, it was confirmed that the electric field strength became weaker (smaller) as the area of ​​the external electrode 55 increased. Note that the temperatures in each experimental result are the actual measurements of the highest temperature point in the third-stage isolated DC-DC converter 13.

[0053] As shown in Figures 6 and 7, the potential on the secondary side (output side) increases as you move to the later stages. Therefore, by focusing on isolated DC-DC converters, where it is necessary to reduce the electric field strength, and implementing measures to reduce the electric field strength, corona discharge can be reduced more efficiently, that is, without implementing unnecessary measures.

[0054] In the above description, the decrease in electric field strength and temperature of the third-stage isolated DC-DC converter 13 was explained, but the embodiment is not limited to this. That is, even if there is only one isolated DC-DC converter 11 (only the first stage) mounted on the circuit board 15, the technical features of this embodiment are applicable and the same effects as described above can be achieved.

[0055] Based on the above, the power supply device according to this embodiment comprises an isolated DC-DC converter with an internal transformer, and a conductor electrically connected to the output terminal of the isolated DC-DC converter outside the isolated DC-DC converter, wherein the conductor is arranged in a direction perpendicular to the direction from the primary side to the secondary side of the transformer, as viewed from the secondary winding of the transformer. With the power supply device configured as described above, the primary winding of the transformer functions as one electrode (primary side electrode) of the capacitor, and the conductor, together with the secondary winding of the transformer, functions as the other electrode (enlarged secondary side electrode) of the capacitor. In the absence of the conductor in this embodiment, the secondary winding of the transformer functions as the other electrode (normal secondary side electrode) of the capacitor. Therefore, the conductor can also be said to be an external electrode to the normal secondary side electrode. Here, since the conductor is arranged outside the isolated DC-DC converter, the enlarged secondary side electrode has a larger area than the normal secondary side electrode. Therefore, since the charge is more dispersed than with a normal secondary electrode, the electric field strength in the secondary winding with an enlarged secondary electrode is weaker (smaller) than the electric field strength in the secondary winding with a normal secondary electrode. Consequently, by implementing the measures of this embodiment, the electric field strength in the secondary winding can be weakened (reduced). Moreover, since the conductor is placed outside the isolated DC-DC converter, there is no need to disassemble or modify the isolated DC-DC converter purchased as a component, so the measures can be easily implemented.

[0056] Furthermore, in the power supply device according to this embodiment, the isolated DC-DC converter and the conductor are provided on a circuit board. Providing both on a circuit board allows for easy installation. For example, by creating a pattern on the circuit board for connecting the output terminal of the isolated DC-DC converter to the conductor, the conductor can be easily attached.

[0057] Furthermore, in the power supply device according to the embodiment, the conductor is a metal spacer, a plate-shaped conductor, or a conductor arranged to surround the secondary winding of the transformer. If the conductor is a metal spacer, it is readily available and easy to install. In particular, if the metal spacer is provided on the circuit board, it becomes easy to remove. Also, the number of metal spacers can be easily adjusted. That is, the area of ​​the enlarged secondary side electrode can be easily adjusted. Note that screw holes for attaching the metal spacers must be created in advance on the circuit board. If the conductor is a plate-shaped conductor, it is easy to secure an area as an external electrode. Therefore, it is easy to disperse the charge, and consequently, it is easy to weaken the electric field strength. If the conductor is arranged to surround the secondary winding of the transformer, the charge can be dispersed not only in one direction but also in the circumferential direction of the secondary winding of the transformer. Therefore, the degree of reduction in electric field strength can be made uniform.

[0058] Furthermore, in the power supply device according to the embodiment, the conductor is composed of a first conductor arranged to surround the secondary winding of the transformer, and a second conductor electrically connected to the first conductor. Since the effects of both the first and second conductors are combined, dielectric loss in the secondary winding can be reduced more effectively.

[0059] Furthermore, in the power supply device according to the embodiment, the isolated DC-DC converter is one of several DC-DC converters connected in series, and is an isolated DC-DC converter whose secondary potential is greater than or equal to a predetermined potential. When several isolated DC-DC converters are connected in series, the problem lies with the isolated DC-DC converters in the later stages. This is because the potential on the secondary side (output side) becomes higher the further down the line you go. Therefore, countermeasures should be focused on the isolated DC-DC converters that need to have their electric field strength reduced. Specifically, the focus should be on the isolated DC-DC converters whose secondary potential (absolute value) is greater than or equal to a predetermined potential (absolute value). This avoids the need for unnecessary countermeasures. Typically, countermeasures are taken on the last isolated DC-DC converter.

[0060] Based on the above, the power supply device according to this embodiment and others makes it possible to weaken (reduce) the electric field strength in the secondary winding of an isolated DC-DC converter without disassembling or modifying the isolated DC-DC converter in a power supply device using an isolated DC-DC converter purchased as a component.

[0061] The embodiments described above can be combined as appropriate and are illustrative examples only, not limiting the scope of the invention. Furthermore, the embodiments and variations described above are included in the scope and gist of the invention and are included in the scope of the invention and its equivalents as described in the claims. [Explanation of Symbols]

[0062] 3 External electrode conductor, 11 First stage isolated DC-DC converter, 12 Second stage isolated DC-DC converter, 13 Third stage isolated DC-DC converter, 14 Last stage external electrode conductor, 15 Circuit board, 17 Input terminal, 19 Output terminal, 21 Pattern wiring, 31 Pseudo corona ring, 32 Metal spacer, 33 Plate-shaped conductor, 51 Enlarged secondary side electrode, 53 Normal secondary side electrode, 55 External electrode, 111 Transformer, 191 Through hole, 311 Screw, 321 Screw, 323 Two metal spacers near the third stage isolated DC-DC converter 13, 324 Copper plate, 331 Screw

Claims

1. An isolated DC-DC converter with an internal transformer, Outside the isolated DC-DC converter, a conductor electrically connected to the output terminal of the isolated DC-DC converter, Equipped with, The conductor is arranged in a direction perpendicular to the direction from the primary side to the secondary side of the transformer. The conductor is a metal spacer, a plate-shaped conductor, or a conductor arranged to surround the secondary winding of the transformer. power supply.

2. An isolated DC-DC converter equipped with a transformer inside, Outside the isolated DC-DC converter, a conductor electrically connected to the output terminal of the isolated DC-DC converter, Equipped with, The conductor is arranged in a direction perpendicular to the direction from the primary side to the secondary side of the transformer. The conductor comprises a first conductor arranged to surround the secondary winding of the transformer, and a second conductor electrically connected to the first conductor. power supply.

3. The isolated DC-DC converter and the conductor are provided on a circuit board. The power supply device according to claim 1 or 2.

4. The aforementioned isolated DC-DC converter is a part of a series of multiple DC-DC converters, and is an isolated DC-DC converter in which the absolute value of the secondary potential is greater than or equal to the absolute value of a predetermined potential. A power supply device according to any one of claims 1 to 3.

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