Transformer and power supply device

Abstract

A transformer (10) for unidirectional or bidirectional power conversion is provided with: a plurality of magnetic cores; a first winding (21) connected to the primary side circuit (41); a second winding (22) connected to the secondary side circuit (42); a resonance capacitor (3); and a third winding (23). The third winding (23) is connected in series with the resonance capacitor (3) inside the transformer (10) to form a closed circuit. The first winding (21), the second winding (22), and the third winding (23) are each wound around one or more magnetic cores among the plurality of magnetic cores.

Description

Technical Field

[0001] The present disclosure relates to a transformer and a power supply device. Background Art

[0002] Patent Document 1 discloses a current resonance switching power supply.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 11-356044 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a transformer and a power supply device that can easily achieve miniaturization of a power supply device using the transformer.

[0008] Solutions for solving problems

[0009] A transformer according to one embodiment of the present disclosure is used for unidirectional or bidirectional power conversion, and includes: a plurality of magnetic cores; a first winding connected to a primary side circuit; a second winding connected to a secondary side circuit; a resonant capacitor; and a third winding connected in series with the resonant capacitor inside the transformer to form a closed circuit. The first winding, the second winding, and the third winding are all wound around one or more of the plurality of magnetic cores.

[0010] The power supply device according to one embodiment of the present disclosure includes: the transformer; the primary circuit, which is a bridge circuit connected to the first winding; and the secondary circuit, which is a bridge circuit connected to the second winding. At least one of the primary circuit and the secondary circuit has a plurality of switching elements.

[0011] Effects of the Invention

[0012] According to the transformer according to one aspect of the present disclosure, there is an advantage that a power supply device using the transformer can be easily miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : is a circuit diagram showing a schematic configuration of a power supply device according to the embodiment.

[0014] Figure 2 It is a cross-sectional view showing a schematic structure of a transformer according to the embodiment.

[0015] Figure 3 It is a diagram showing a schematic structure of the tertiary winding and the resonance capacitor.

[0016] Figure 4 : is a circuit diagram showing a schematic configuration of a power supply device according to a comparative example.

[0017] Figure 5 1 is a diagram showing an equivalent circuit including a transformer and two resonant capacitors according to a comparative example.

[0018] Figure 6 : is a diagram showing an equivalent circuit of a transformer according to the embodiment.

[0019] Figure 7 It is a diagram showing the comparison result between the power supply device according to the embodiment and the power supply device of the comparative example.

[0020] Figure 8 It is a diagram showing a schematic structure of a modified example of the tertiary winding.

[0021] Fig. 9 1 is a diagram showing a schematic structure of a modified example of the tertiary winding and the resonant capacitor.

[0022] Fig.10 It is a diagram showing a schematic structure of another modified example of the tertiary winding and the resonant capacitor.

[0023] Fig.11 1 is a diagram showing a schematic structure of still another modified example of the tertiary winding and the resonant capacitor.

[0024] Fig.12 It is a diagram showing a schematic structure of a modification of a plurality of magnetic cores.

[0025] Fig.13 It is a diagram showing a schematic structure of another modified example of the plurality of magnetic cores.

[0026] Fig.14 It is a diagram showing a schematic structure of a modified example of the first winding and the second winding.

[0027] Fig.15 It is a cross-sectional view showing a schematic structure of a transformer according to a first modified example of the embodiment.

[0028] Fig.16 It is a cross-sectional view showing a schematic structure of a transformer according to a second modification example of the embodiment.

[0029] Fig.17 It is a diagram showing a schematic structure of a modification of a plurality of magnetic cores. DETAILED DESCRIPTION

[0030] (Insights that form the basis of this disclosure)

[0031] First, the inventor's focus is described below.

[0032] In order to improve the conversion efficiency of a bidirectional power supply device that steps up or down an input voltage from either a primary side circuit or a secondary side circuit and then outputs it bidirectionally to the other circuit, a CLLC current resonance power supply is used, which includes a plurality of switching elements, a transformer, an inductor and a capacitor arranged on the primary side of the transformer, and an inductor and a capacitor arranged on the secondary side of the transformer.

[0033] In conventional current resonance type power supplies, since the current flowing in the switching element is a resonant current that reverses positive and negative, the switching element is switched on / off at the same time as the current flowing therein becomes zero, thereby achieving Zero Current Switching (ZCS: zero current switching), which can reduce the loss of the switching element. In addition, by matching the switching element on time with the period when the current flowing therein is negative, the parasitic capacitance (output capacitance) of the switching element is discharged, and the voltage applied to the switching element becomes zero, thereby achieving Zero Voltage Switching (ZVS: zero voltage switching), which can also reduce the loss of the switching element.

[0034] In this way, since the loss when switching the switching element on / off is very small, the current resonance type power supply can drive the switching element at a high frequency. On the other hand, the switching power supply using the switching element can miniaturize the passive elements such as the transformer, inductor and capacitor in the power supply device by driving the switching element at a high frequency. Therefore, in order to miniaturize the transformer and the power supply device, it is effective to apply the current resonance type power supply.

[0035] However, the current resonance type power supply uses a large amplitude resonance current, so a very high voltage is generated in the transformer, inductor and capacitor constituting the resonance circuit. The structure of the power supply needs to be designed in a way to ensure a long insulation distance in the resonance circuit, between the resonance circuit and the primary side circuit, and between the resonance circuit and the secondary side circuit, respectively, making it difficult to miniaturize the power supply device. In addition, the insulation distance is not only related to the magnitude of the voltage between the terminals, but the international standards such as the IEC (International Electrotechnical Commission) stipulate that the higher the voltage cycle between the terminals, that is, the higher the driving frequency of the power supply, the longer the insulation distance to be ensured. Therefore, there is a problem that even if the switching element is driven at a high frequency to miniaturize the passive elements in the power supply device, the insulation distance in the power supply device needs to be extended as a trade-off, making it difficult to miniaturize the transformer and the power supply device.

[0036] In view of the above, the inventors created the present disclosure.

[0037] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0038] In addition, the embodiments to be described below all represent general or specific examples. The numerical values, shapes, structural elements, configuration positions and connection methods of the structural elements shown in the following embodiments are examples, and their purpose is not to limit the present disclosure. In addition, the structural elements in the following embodiments that are not described in the independent claims are described as arbitrary structural elements.

[0039] In addition, each figure is a schematic diagram and may not be strictly illustrated. Therefore, for example, the scales in each figure may not be consistent. In addition, in each figure, the same reference numerals are marked for substantially the same structure, and repeated descriptions are omitted or simplified.

[0040] In addition, in this specification, terms such as orthogonal, parallel, and identical that indicate the relationship between elements, terms such as rectangular and circular that indicate the shapes of elements, and numerical values ​​and numerical ranges are not intended to have strict meanings, but also mean to include substantially equivalent ranges, such as differences of about a few percent (for example, about 10%).

[0041] (Implementation Method)

[0042] The transformer 10 and the power supply device 100 according to the embodiment are described below. The power supply device 100 is a device that steps up or steps down an input voltage to a predetermined voltage and outputs the voltage. For example, the power supply device 100 steps up or steps down an input voltage to a predetermined voltage and outputs the voltage. Figure 1 ) is stepped up or down to a predetermined voltage and then fed to the secondary circuit 42 (refer to Figure 1 ) output. In addition, for example, the power supply device 100 is a bidirectional DC / DC converter that steps up or steps down the input voltage from either the primary side circuit 41 or the secondary side circuit 42 and outputs it to the other circuit. Here, the power supply device 100 is described as a bidirectional DC / DC converter. The power supply device 100 is used, for example, to charge and discharge each battery by passing power between a battery installed in a household and a battery mounted in an electric vehicle.

[0043] [Structure of power supply device]

[0044] First, use Figure 1 The structure of the power supply device 100 according to the embodiment will be described. Figure 1 1 is a circuit diagram showing a schematic structure of a power supply device 100 according to an embodiment. Figure 1As shown, the power supply device 100 includes a transformer 10, a primary side circuit 41, and a secondary side circuit 42. In addition, although not shown, the power supply device 100 may also include a control circuit that controls the primary side circuit 41 and the secondary side circuit 42. In other words, the control circuit may be a component of the power supply device 100 or may not be a component of the power supply device 100.

[0045] exist Figure 1 In the figure, "Lm" represents the excitation inductance, "Lr1" represents the leakage inductance of the first winding 21, "Lr2" represents the leakage inductance of the second winding 22, and "Lr3" represents the leakage inductance of the third winding 23. In addition, "C0" represents the capacitance of the resonance capacitor 3. Figure 1 In the figure, the winding resistance and parasitic capacitance are omitted.

[0046] Compared with the power supply device 200 of the comparative example described later (refer to Figure 4 ) Similarly, the primary side circuit 41 is a full bridge circuit having four switching elements Q1 to Q4. That is, the primary side circuit 41 is a bridge circuit. The four switching elements Q1 to Q4 are, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The primary side circuit 41 is formed by connecting a series circuit of switching elements Q1 and Q2 in parallel with a series circuit of switching elements Q3 and Q4.

[0047] The primary side circuit 41 controls the switching elements Q1 to Q4 by the control circuit, so as to convert the DC voltage input from the first external circuit (e.g., a battery) to the primary side circuit 41 into an AC voltage and output it to the transformer 10. In addition, the primary side circuit 41 controls the switching elements Q1 to Q4 by the control circuit, so as to convert the AC voltage output from the transformer 10 into a DC voltage and output it to the first external circuit.

[0048] Compared with the power supply device 200 of the comparative example described later (refer to Figure 4 ) Similarly, the secondary side circuit 42 is a full bridge circuit having four switching elements Q5 to Q8. That is, the secondary side circuit 42 is a bridge circuit. The four switching elements Q5 to Q8 are each, for example, an N-channel MOSFET. The secondary side circuit 42 is formed by connecting a series circuit of switching elements Q5 and Q6 in parallel with a series circuit of switching elements Q7 and Q8.

[0049] The secondary circuit 42 controls the switching elements Q5 to Q8 by the control circuit, so that the DC voltage input from the second external circuit (e.g., a battery) is converted into an AC voltage and outputted to the transformer 10. In addition, the secondary circuit 42 controls the switching elements Q5 to Q8 by the control circuit, so that the AC voltage outputted from the transformer 10 is converted into a DC voltage and outputted to the second external circuit.

[0050] As described above, in the embodiment, the primary side circuit 41 as a bridge circuit and the secondary side circuit 42 as a bridge circuit each have a plurality of switching elements.

[0051] [Transformer structure]

[0052] Next, use Figure 1 and Figure 2 The structure of the transformer 10 according to the embodiment will be described. Figure 2 1 is a cross-sectional view showing a schematic structure of a transformer 10 according to an embodiment. The transformer 10 is used for unidirectional or bidirectional power conversion. In the embodiment, the transformer 10 is used for bidirectional power conversion. Figure 1 and Figure 2 As shown, the transformer 10 includes a plurality of (here, two) magnetic cores 1, a first winding 21, a second winding 22, a third winding 23, and a resonant capacitor 3. Hereinafter, one of the two magnetic cores 1 is also referred to as a "first magnetic core 11", and the other magnetic core 1 is also referred to as a "second magnetic core 12".

[0053] The first magnetic core 11 is formed of a magnetic material such as ferrite, for example, and has three legs 111, which are configured in an E-shape in a cross-sectional view. The second magnetic core 12 is similar to the first magnetic core 11, and is formed of a magnetic material such as ferrite, for example, and has three legs 121, which are configured in an E-shape in a cross-sectional view. The three legs 111 of the first magnetic core 11 and the three legs 121 of the second magnetic core 12 are configured so that the legs are butted against each other. Therefore, in the embodiment, the first magnetic core 11 and the second magnetic core 12 constitute a so-called EE magnetic core. In addition, a gap G1 is provided between the central leg 111 of the three legs 111 of the first magnetic core 11 and the central leg 121 of the three legs 121 of the second magnetic core 12.

[0054] The first winding 21 is connected to the primary side circuit 41. In the embodiment, the first winding 21 is formed by winding a conductive wire around the leg portion 111 in the center of the first magnetic core 11. In addition, both ends of the first winding 21 are connected to a pair of output terminals of the primary side circuit 41 when the primary side is set as input (a pair of input terminals of the primary side circuit 41 when the secondary side is set as input).

[0055] The second winding 22 is connected to the secondary side circuit 42. In the embodiment, the second winding 22 is formed by winding a conductive wire around the central leg 111 of the first magnetic core 11 and the central leg 121 of the second magnetic core 12. In addition, both ends of the second winding 22 are connected to a pair of input terminals of the secondary side circuit 42 when the primary side is set as input (a pair of output terminals of the secondary side circuit 42 when the secondary side is set as input).

[0056] The third winding 23 is connected in series with the resonant capacitor 3 to form a closed circuit inside the transformer 10. As described later, the closed circuit formed by the third winding 23 and the resonant capacitor 3 functions as a resonant circuit on the primary side of the transformer 10, and also functions as a resonant circuit on the secondary side of the transformer 10.

[0057] In an embodiment, if Figure 3 As shown, the third winding 23 is composed of a conductor pattern 231 formed on the substrate 5 having the through hole 51 . Figure 3 2 is a diagram showing a schematic structure of the third winding 23 and the resonant capacitor 3. Specifically, the substrate 5 is, for example, a rectangular printed circuit board, and has a rectangular through hole 51 penetrating in the thickness direction at its center. In addition, a conductor pattern 231 is formed on the surface of the substrate 5 and is arranged around the through hole 51 in a spiral shape when viewed from the thickness direction of the substrate 5. In addition, the shape of the substrate 5 and the shape of the through hole 51 are not limited to a rectangular shape, and may be other shapes such as a circular shape.

[0058] The starting end and the terminal end of the conductor pattern 231 are connected through the resonance capacitor 3. Thus, the conductor pattern 231 (third winding 23) is connected in series with the resonance capacitor 3. In the embodiment, the resonance capacitor 3 is a surface-mounted capacitor, but is not limited to this, and may be a lead terminal type capacitor, for example. Furthermore, by configuring the substrate 5 in such a manner that the leg portion of any one of the plurality of cores 1 (here, the central leg portion 121 of the second core 12) is inserted into the through hole 51, the conductor pattern 231 (third winding 23) is wound around the core 1 (second core 12).

[0059] Here, “the third winding 23 is connected in series with the resonant capacitor 3 inside the transformer 10 to form a closed circuit” means that the third winding 23 and the resonant capacitor 3 form a closed circuit in a state where the connection portion between the third winding 23 and the resonant capacitor 3 cannot be connected to an external circuit of the transformer 10. “The state where the connection portion between the third winding 23 and the resonant capacitor 3 cannot be connected to an external circuit of the transformer 10” means, for example, a state where the third winding 23 does not have a connection terminal for connecting to an external circuit of the transformer 10. In addition, for example, the above state means a state where at least the connection portion between the third winding 23 and the resonant capacitor 3 is not exposed to the outside of the transformer 10 and cannot be visually recognized by a person. In addition, for example, the above state means a state where the connection portion between the third winding 23 and the resonant capacitor 3 is exposed to the outside of the transformer 10 but an operation to connect an external circuit to the connection portion cannot be performed.

[0060] In the embodiment, the substrate 5 on which the conductor pattern 231 (third winding 23) and the resonant capacitor 3 are mounted is arranged in a space surrounded by the first core 11 and the second core 12. Therefore, the connection portion between the conductor pattern 231 and the resonant capacitor 3 is not exposed to the outside of the transformer 10.

[0061] As described above, the first winding 21, the second winding 22, and the third winding 23 are all wound around the central leg 111 of the first magnetic core 11 or the central leg 121 of the second magnetic core 12. That is, the first winding 21, the second winding 22, and the third winding 23 are all wound around at least one of the plurality of magnetic cores 1. Therefore, the first winding 21 and the second winding 22, the second winding 22 and the third winding 23, and the first winding 21 and the third winding 23 are magnetically coupled, respectively.

[0062] In the embodiment, the first winding 21 and the second winding 22, the second winding 22 and the third winding 23, and the first winding 21 and the third winding 23 are loosely magnetically coupled to each other. For example, when the inductance is observed from the other side in a state where either the primary side or the secondary side is short-circuited, if the inductance has a significant value, leakage inductance exists, and it can be said that the first winding 21 and the second winding 22 are loosely coupled to each other.

[0063] In the embodiment, the coupling coefficient between the first winding 21 and the second winding 22, the coupling coefficient between the second winding 22 and the third winding 23, and the coupling coefficient between the first winding 21 and the third winding 23 are all less than 0.96. In addition, the numerical range of the coupling coefficient equivalent to loose magnetic coupling listed here is an example, and other numerical ranges may be used.

[0064] [action]

[0065] Next, an operation example of the power supply device 100 according to the embodiment will be described. Figure 4 and Figure 5 The operation of the power supply device 200 of the comparative example will be described. Figure 4 : is a circuit diagram showing a schematic configuration of a power supply device 200 according to a comparative example.

[0066] Figure 5 1 is a diagram showing an equivalent circuit including a transformer 300 and two resonance capacitors 303 and 304 according to a comparative example.

[0067] exist Figure 5 In , "Lm1" represents the excitation inductance, "Lr11" represents the leakage inductance of the first winding 301, and "Lr12" represents the leakage inductance of the second winding 302. In addition, "C1" represents the capacitance of the first resonant capacitor 303, and "C2" represents the capacitance of the second resonant capacitor 304. In addition, Figure 5 In the figure, the winding resistance and parasitic capacitance are omitted.

[0068] The power supply device 200 of the comparative example differs from the power supply device 100 according to the embodiment in that it includes a transformer 300 of the comparative example instead of the transformer 10, and further includes a first resonant capacitor 303 and a second resonant capacitor 304. Hereinafter, description of the common points with the power supply device 100 according to the embodiment will be appropriately omitted.

[0069] The transformer 300 of the comparative example includes a first winding 301 connected to the primary circuit 41 and a second winding 302 connected to the secondary circuit 42. In addition, the transformer 300 of the comparative example does not include the third winding 23 and the resonance capacitor 3, unlike the transformer 10 according to the embodiment. The first winding 301 and the second winding 302 are loosely magnetically coupled to each other.

[0070] The first resonant capacitor 303 is connected in series with the first winding 301. The first resonant capacitor 303 and the leakage inductance of the first winding 301 constitute a resonant circuit on the primary side (see Figure 5 The second resonant capacitor 304 is connected in series with the second winding 302. The second resonant capacitor 304 and the leakage inductance of the second winding 302 constitute a resonant circuit on the secondary side (see Figure 5 dotted line).

[0071] In the power supply device 200 of the comparative example, for example, during power operation such as charging a battery connected to the secondary circuit 42, as shown in FIG. Figure 5As shown in FIG. 1 , the leakage inductance of the first winding 301 resonates with the first resonant capacitor 303. In the power supply device 200 of the comparative example, when the battery connected to the secondary side circuit 42 is discharged or regenerated, for example, Figure 5 As shown, the leakage inductance of the second winding 302 resonates with the second resonant capacitor 304. In this way, the power supply device 200 of the comparative example can perform soft switching of each switching element in both the primary circuit 41 and the secondary circuit 42, thereby reducing switching loss and improving efficiency.

[0072] However, in the power supply device 200 of the comparative example, since it is necessary to arrange the resonance capacitors on both the primary side and the secondary side, there is a problem that the functionality is lacking and it is difficult to achieve miniaturization of the device.

[0073] In the power supply device 200 of the comparative example, Figure 4 In the power operation, the leakage inductance of the first winding 301 and the resonance action of the first resonant capacitor 303 generate a relatively high resonant voltage, and this resonant voltage is also applied to the transformer 300 of the comparative example. Similarly, in the power supply device 200 of the comparative example, Figure 4 In the case of regeneration, a relatively high resonant voltage is generated due to the resonant action of the leakage inductance of the second winding 302 and the second resonant capacitor 304, and this resonant voltage is also applied to the transformer 300 of the comparative example.

[0074] Thus, in the power supply device 200 of the comparative example, a relatively high voltage is generated not only at both ends of the first resonant capacitor 303 and at both ends of the second resonant capacitor 304, but also at both ends of the primary winding and at both ends of the secondary winding of the transformer 300 of the comparative example. Therefore, in the power supply device 200 of the comparative example, relatively high voltages are generated at the transformer 300 of the comparative example, the connection portion between the primary side circuit 41 and the first resonant capacitor 303, and the connection portion between the secondary side circuit 42 and the second resonant capacitor 304, and thus there is a problem that an insulation design capable of withstanding such voltages is required, and it is difficult to achieve miniaturization of the device.

[0075] Furthermore, the international standard IEC60664-4 stipulates the spatial distance and creepage distance when subjected to repetitive voltage stress with a fundamental frequency exceeding 30kHz, and the higher the frequency and voltage of the stress voltage, the longer the distance required for insulation. Therefore, in the comparative example power supply device 200, when the switching elements Q1 to Q4 and Q5 to Q8 are driven at a high frequency in order to miniaturize the transformer 300, which is a large component, a relatively high voltage of high frequency is generated at the connection part of the transformer 300, the primary side circuit 41 and the first resonant capacitor 303, and the connection part of the secondary side circuit 42 and the second resonant capacitor 304 of the comparative example, so the spatial distance and creepage distance of the parts need to be designed to be long, which also leads to the problem that it is difficult to further miniaturize the device.

[0076] On the other hand, the power supply device 100 according to the embodiment includes the transformer 10 according to the embodiment, and thus can solve the above-mentioned problem. Figure 6 The operation of the power supply device 100 according to the embodiment will be described. Figure 6 2 is a diagram showing an equivalent circuit of the transformer 10 according to the embodiment.

[0077] exist Figure 6 In the figure, "Lm" represents the excitation inductance, "Lr1" represents the leakage inductance of the first winding 21, "Lr2" represents the leakage inductance of the second winding 22, and "Lr3" represents the leakage inductance of the third winding 23. In addition, "C0" represents the capacitance of the resonance capacitor 3. Figure 5 In the figure, the winding resistance and parasitic capacitance are omitted.

[0078] As already described, the third winding 23 is connected in series with the resonant capacitor 3 inside the transformer 10 to form a closed circuit. Figure 6 As shown, the leakage inductance of the third winding 23 and the resonance capacitor 3 constitute a primary side resonance circuit (see Figure 6 dotted line) and form a resonant circuit on the secondary side (refer to Figure 6 dotted line).

[0079] In the power supply device 100 according to the embodiment, for example, during power operation such as charging a battery connected to the secondary circuit 42, as shown in FIG. Figure 6 As shown, the leakage inductance of the third winding 23 resonates with the resonance capacitor 3. In the power supply device 100 according to the embodiment, for example, when the battery connected to the secondary side circuit 42 is discharged or regenerated, as shown in FIG. Figure 6As shown, the leakage inductance of the third winding 23 resonates with the resonant capacitor 3. In this way, the power supply device 100 according to the embodiment can perform soft switching of each switching element in both the primary circuit 41 and the secondary circuit 42, thereby reducing switching loss and improving efficiency.

[0080] Moreover, in the power supply device 100 involved in the embodiment, there is no need to configure resonance capacitors on both the primary side and the secondary side, and only one resonance capacitor 3 provided in the transformer 10 can be used. Therefore, compared with the power supply device 200 of the comparative example, it is easy to improve functionality, easy to miniaturize the device, and easy to reduce costs.

[0081] In addition, in the power supply device 100 according to the embodiment, as Figure 1 As shown, during both power operation and regeneration, a relatively high resonant voltage is generated due to the resonant action of the leakage inductance of the third winding 23 and the resonant capacitor 3. Moreover, this resonant voltage is generated inside the transformer 10, so it is not applied to either the primary side circuit 41 or the secondary side circuit 42.

[0082] Figure 7 1 is a diagram showing the comparison results between the power supply device 100 according to the embodiment and the power supply device 200 according to the comparative example. Figure 7 In FIG. 4 , the vertical axis represents the terminal voltage and the horizontal axis represents the time. The terminal voltage is the primary voltage or the secondary voltage of the transformer, in other words, the voltage applied to the primary side circuit 41 or the voltage applied to the secondary side circuit 42. Figure 7 In the figure, the solid line represents the primary voltage of the transformer, and the dotted line represents the secondary voltage of the transformer. Figure 7 (a) shows a waveform diagram of the terminal voltage of the power supply device 200 of the comparative example, Figure 7 (b) is a waveform diagram of the terminal voltage of the power supply device 100 according to the embodiment.

[0083] In the power supply device 200 of the comparative example, as Figure 7 As shown in (a), the primary voltage of the transformer is a voltage obtained by further superimposing a resonance voltage of about 200 V on an AC voltage with an amplitude of about 400 V. In the power supply device 200 of the comparative example, the secondary voltage of the transformer is a voltage obtained by further superimposing a resonance voltage of about 200 V on an AC voltage with an amplitude of about 200 V.

[0084] In contrast, in the power supply device 100 according to the embodiment, Figure 7As shown in (b), the primary voltage of the transformer is an AC voltage with an amplitude of about 400 V, and no resonance voltage is superimposed. In the power supply device 100 according to the embodiment, the secondary voltage of the transformer is an AC voltage with an amplitude of about 200 V, and no resonance voltage is superimposed.

[0085] As described above, in the power supply device 100 according to the embodiment, it is only necessary to perform an insulation design capable of withstanding a relatively high voltage in the transformer 10, so it is easy to achieve miniaturization of the device. Therefore, compared with the power supply device 200 of the comparative example, the transformer 10 according to the embodiment has an advantage that it is easy to achieve miniaturization of the power supply device 100 using the transformer 10.

[0086] (Other Embodiments)

[0087] The transformer 10 and the power supply device 100 involved in the embodiment are described above, but the present disclosure is not limited to the embodiment. As long as it does not depart from the main purpose of the present disclosure, the embodiment can be implemented by various deformations that can be thought of by those skilled in the art, and the structure elements in different embodiments can be combined and constructed. The method can also be included in the present disclosure.

[0088] In an embodiment, if Figure 8 As shown, the conductor pattern 231 (third winding 23) may also be provided inside the substrate 5A. Figure 8 It is a cross-sectional view showing a schematic structure of a modified example of the third winding 23 .

[0089] Specifically, the substrate 5A is, for example, a rectangular multilayer printed circuit board, and although not shown, has a through hole in its central portion similarly to the substrate 5. Furthermore, the conductor pattern 231 is not formed on the surface of the substrate 5A, but is formed in a layer located inside the substrate 5A among the multiple layers of the substrate 5A. In addition, the shape of the substrate 5A and the shape of the through hole are not limited to a rectangular shape, and may be other shapes such as a circular shape.

[0090] In the above-described structure, since most of the conductor pattern 231 (third winding 23) is covered by the substrate 5A made of a material having insulating properties, there is an advantage that the insulation distance to be ensured can be shortened.

[0091] In addition, in the above structure, if Fig. 9 As shown, the resonant capacitor 3 may be provided inside the substrate 5A. Fig. 92 is a cross-sectional view showing a schematic structure of a modified example of the third winding 23 and the resonant capacitor 3. Specifically, the resonant capacitor 3 is connected to the starting end and both ends of the conductor pattern 231 in a layer located inside the substrate 5A among the multiple layers of the substrate 5A. In the above structure, the resonant capacitor 3 is covered by the substrate 5A made of an insulating material, so there is an advantage that the insulation distance to be ensured can be shortened.

[0092] In the above structure, the first winding 21 and the second winding 22 may also be formed of conductor patterns. For example, the conductor pattern of the first winding 21 may be formed on one surface in the thickness direction of the substrate 5A, and the conductor pattern of the second winding 22 may be formed on the other surface in the thickness direction of the substrate 5A.

[0093] In an embodiment, for example Fig.10 As shown, the third winding 23 may be formed by winding the conductive wire 232 around the leg portions 111 and 121 of any one of the plurality of cores 1 . Fig.10 2 is a diagram showing a schematic structure of another modified example of the third winding 23 and the resonant capacitor 3. Fig.10 In the figure, the magnetic core 1 is omitted. In this structure, the resonance capacitor 3 is connected to the beginning and the end of the wire 232. The resonance capacitor 3 is a lead terminal type capacitor, but is not limited to this, and may be a surface mount type capacitor, for example. In addition, when the resonance capacitor 3 is a surface mount type capacitor, it is sufficient to have a substrate for mounting the capacitor separately.

[0094] In addition, if Fig.11 As shown, the third winding 23 and the resonance capacitor 3 may be covered by an insulator 6 made of a material having insulating properties. Fig.11 1 is a diagram showing a schematic structure of still another modified example of the tertiary winding 23 and the resonant capacitor 3 .

[0095] Specifically, the insulator 6 is formed of a resin material having insulating properties and is cylindrical. Fig.11 A circular through hole 61 is formed which penetrates the through hole 61 in the vertical direction. The conductive wire 232 is spirally arranged around the through hole 61.

[0096] In the embodiment, the first magnetic core 11 and the second magnetic core 12 constitute a so-called EE magnetic core, but are not limited thereto. For example, Fig.12 The structure shown. Fig.12 1 is a diagram showing a schematic structure of a modification of a plurality of magnetic cores 1. Fig.12As shown in (a), the first magnetic core 11 and the second magnetic core 12 may also constitute a so-called EI magnetic core. In this structure, the first magnetic core 11 has three legs 111, and the second magnetic core 12 is in the shape of a rod. In addition, for example Fig.12 As shown in (b), the first magnetic core 11 and the second magnetic core 12 may also constitute a so-called EER magnetic core. In this structure, the first magnetic core 11 has three legs 111, and the central leg 111 is cylindrical. In addition, the second magnetic core 12 has three legs 121, and the central leg 121 is cylindrical. In addition, for example Fig.12 As shown in (c), the first magnetic core 11 and the second magnetic core 12 can also constitute a so-called PQ magnetic core. In this structure, the first magnetic core 11 and the second magnetic core 12 are Fig.12 The structure of (b) is based on the shape that gradually tapers from the outer leg to the central leg.

[0097] In addition, in the embodiment, there are two magnetic cores 1, but it is not limited thereto. Fig.13 As shown, there may be more than three. Fig.13 1 is a diagram showing a schematic structure of another modified example of the plurality of magnetic cores 1. Fig.13 As shown in (a), regarding the plurality of magnetic cores 1, a so-called EE magnetic core may be formed by three magnetic cores 1. In this structure, the plurality of magnetic cores 1 have a third magnetic core 13 in addition to the first magnetic core 11 and the second magnetic core 12. In addition, for example Fig.13 As shown in (b), regarding the plurality of magnetic cores 1, a so-called EE magnetic core may be formed by four magnetic cores 1. In this structure, in addition to the first magnetic core 11, the second magnetic core 12, and the third magnetic core 13, a fourth magnetic core 14 is also provided. In addition, for example Fig.13 As shown in (c), regarding the plurality of cores 1, a so-called EE core may be formed by five cores 1. In this structure, in addition to the first core 11, the second core 12, the third core 13 and the fourth core 14, there is also a fifth core 15. In addition, in this structure, two gaps G1 are provided.

[0098] In addition, for example Fig.13 (d) and Fig.13 As shown in (e) of FIG. 1 , a plurality of cores 1 may be formed into a so-called EE core by three cores 1. Fig.13 (d) and Fig.13 In the structure shown in (e), two gaps G1 are provided.

[0099] In addition, in the embodiment, the first winding 21 and the second winding 22 are both formed by winding the wire around the central leg 111 of the first magnetic core 11 or the central leg 121 of the second magnetic core 12, but it is not limited thereto. Fig.14 As shown. Fig.14 2 is a diagram showing a schematic structure of a modified example of the first winding 21 and the second winding 22. Fig.14 In the embodiment, the first magnetic core 11 and the second magnetic core 12 constitute a so-called EI magnetic core. Fig.14 As shown, the first winding 21 and the second winding 22 can also be formed by winding the wire around the left and right legs 121 of the three legs 121 of the second magnetic core 12. In other words, the first winding 21 and the second winding 22 can be formed by winding the wire around any leg. The third winding 23 is the same.

[0100] Fig.15 1 is a cross-sectional view showing a schematic structure of a transformer 10A according to a first modification of the embodiment. The transformer 10A according to the first modification differs from the transformer 10 according to the embodiment in that it further includes a housing 7. In the following description of the transformer 10A according to the first modification, description of points common to the transformer 10 according to the embodiment will be omitted as appropriate.

[0101] The housing 7 is made of metal, for example, and is formed so that one surface (here Fig.15 The housing 7 is a rectangular parallelepiped with an opening on the upper surface thereof. The housing 7 accommodates a plurality of magnetic cores 1 (a first magnetic core 11 and a second magnetic core 12), a first winding 21, a second winding 22, a third winding 23, and a resonance capacitor 3. The housing 7 is filled with a resin 71 having thermal conductivity.

[0102] In the transformer 10A according to the first modification, the plurality of magnetic cores 1 etc. are covered with the resin 71 having thermal conductivity and housed in the case 7, so that the heat dissipation of the plurality of magnetic cores 1 etc. can be improved. Furthermore, if the resin 71 has high insulation properties, the insulation distance to be ensured can be shortened.

[0103] Fig.16 1 is a cross-sectional view showing a schematic structure of a transformer 10B according to a second modification of the embodiment. The transformer 10B according to the second modification differs from the transformer 10A according to the first modification in that the first magnetic core 11 and the second magnetic core 12 constitute a so-called UU magnetic core. In the following description of the transformer 10B according to the second modification, description of the common points with the transformer 10A according to the first modification will be omitted as appropriate.

[0104] The first magnetic core 11 has two legs 111, which are configured to be U-shaped in a cross-sectional view. The second magnetic core 12 has two legs 121, similarly to the first magnetic core 11, which are configured to be U-shaped in a cross-sectional view. The two legs 111 of the first magnetic core 11 and the two legs 121 of the second magnetic core 12 are configured so that the legs are butted against each other. Therefore, in the second variant, the first magnetic core 11 and the second magnetic core 12 constitute a so-called UU magnetic core. In addition, a gap G1 is provided between one leg 111 of the two legs 111 of the first magnetic core 11 and one leg 121 of the two legs 121 of the second magnetic core 12.

[0105] In the second modification, the first winding 21 and the third winding 23 are wound around one leg 111 of the two legs 111 of the first magnetic core 11 and one leg 121 of the two legs 121 of the second magnetic core 12. In addition, the second winding 22 is wound around the other leg 111 of the first magnetic core 11 and the other leg 121 of the second magnetic core 12.

[0106] In the transformer 10B according to the second modification, the plurality of magnetic cores 1 may be arranged as follows. Fig.17 As shown. Fig.17 1 is a cross-sectional view showing a schematic structure of a modified example of a plurality of magnetic cores 1. Fig.17 As shown, the first magnetic core 11 and the second magnetic core 12 may also constitute a so-called UI magnetic core. In this structure, the first magnetic core 11 has two legs 111, and the second magnetic core 12 is in a rod shape.

[0107] In the embodiment, the first winding 21, the second winding 22 and the third winding 23 may also be different from Figure 2 As shown in the figure, the first winding 21, the second winding 22 and the third winding 23 are arranged in the order of the vertical direction. That is to say, the first winding 21, the second winding 22 and the third winding 23 can be configured in a manner of being wound around at least one of the plurality of magnetic cores 1, and their arrangement is not particularly limited. For example, the first winding 21 and the second winding 22 may be arranged in a manner arranged in the left-right direction, and the third winding 23 may be arranged in a manner arranged in the vertical direction with the first winding 21 and the second winding 22. In addition, for example, the first winding 21, the second winding 22 and the third winding 23 may be arranged in a manner arranged in the left-right direction.

[0108] In the embodiment, both the primary circuit 41 and the secondary circuit 42 are full-bridge circuits having four switching elements, but the present invention is not limited thereto. For example, at least one of the primary circuit 41 and the secondary circuit 42 may be a half-bridge circuit having two switching elements.

[0109] As described in the embodiment, the power supply device 100 may be a unidirectional DC / DC converter. When the power supply device 100 is a unidirectional DC / DC converter, one of the primary side circuit 41 and the secondary side circuit 42 may be a bridge circuit that converts a DC voltage into an AC voltage, and the other circuit may be a bridge circuit for rectification. In addition, the bridge circuit for rectification may be a diode bridge circuit or a bridge circuit for synchronous rectification.

[0110] (Summarize)

[0111] As described above, the transformer 10, 10A, 10B involved in the first embodiment of the present disclosure is used for unidirectional or bidirectional power conversion, and the transformer includes: a plurality of magnetic cores 1; a first winding 21 connected to a primary side circuit 41; a second winding 22 connected to a secondary side circuit 42; a resonance capacitor 3; and a third winding 23. The third winding 23 is connected in series with the resonance capacitor 3 inside the transformer 10, 10A, 10B to form a closed circuit. The first winding 21, the second winding 22, and the third winding 23 are all wound around one or more magnetic cores 1 among the plurality of magnetic cores 1.

[0112] According to this structure, it is not necessary to configure a resonance capacitor on both the primary side and the secondary side, and only one resonance capacitor 3 provided in the transformer 10, 10A, 10B can be used, so it is easy to achieve miniaturization of the device. In addition, according to this structure, it is only necessary to perform an insulation design that can withstand a relatively high voltage in the transformer 10, 10A, 10B, so it is easy to achieve miniaturization of the device. Therefore, according to this structure, there is an advantage that it is easy to achieve miniaturization of the power supply device 100 using the transformer 10, 10A, 10B.

[0113] In addition, the transformer 10, 10A, 10B according to the second aspect of the present disclosure further includes a substrate 5, 5A according to the first aspect, wherein the substrate 5, 5A has a through hole 51 that penetrates in the thickness direction and into which the leg portion 111, 121 of any one of the plurality of magnetic cores 1 is inserted. The third winding 23 is composed of a conductor pattern 231 formed on the substrate 5, 5A.

[0114] According to this configuration, there is an advantage that the area occupied by the third winding 23 can be reduced compared to the case where the third winding 23 is formed by winding a conductive wire around the leg portion of the magnetic core 1 .

[0115] Furthermore, in the transformer 10 , 10A, 10B according to the third aspect of the present disclosure, according to the second aspect, the third winding 23 is provided inside the substrate 5A.

[0116] According to this structure, since most of the conductor pattern 231 (third winding 23) is covered by the substrate 5A made of a material having insulating properties, there is an advantage that the insulation distance to be ensured can be shortened.

[0117] Furthermore, in the transformer 10 , 10A, 10B according to the fourth aspect of the present disclosure, according to the third aspect, the resonant capacitor 3 is provided inside the substrate 5A.

[0118] According to this structure, since the resonance capacitor 3 is covered with the substrate 5A made of a material having insulating properties, there is an advantage that the insulation distance to be ensured can be shortened.

[0119] In the transformer 10 , 10A, 10B according to the fifth aspect of the present disclosure, according to the first aspect, the third winding 23 is formed by winding the conductive wire 232 around the leg portion 111 , 121 of any one of the plurality of cores 1 .

[0120] This configuration has the advantage that the third winding 23 can be configured without preparing a substrate.

[0121] Furthermore, in the transformer 10 , 10A, 10B according to the sixth aspect of the present disclosure, according to any one of the first to fifth aspects, the third winding 23 and the resonance capacitor 3 are covered with an insulating resin.

[0122] According to this structure, since the third winding 23 and the resonance capacitor 3 are covered with the resin having insulating properties, there is an advantage that the insulation distance to be ensured can be shortened.

[0123] In the transformer 10A or 10B according to the seventh aspect of the present disclosure, according to any one of the first to sixth aspects, the transformer further includes a housing 7 that houses the plurality of magnetic cores 1, the first winding 21, the second winding 22, the third winding 23, and the resonance capacitor 3. The housing 7 is filled with a resin 71 having thermal conductivity.

[0124] According to this structure, the plurality of magnetic cores 1 and the like are covered with the resin 71 having thermal conductivity and housed in the case 7 , so there is an advantage that the heat dissipation of the plurality of magnetic cores 1 and the like can be improved.

[0125] In addition, the power supply device 100 according to the eighth aspect of the present disclosure includes: the transformer 10, 10A, 10B of any one of the first to seventh aspects; the primary side circuit 41, which is a bridge circuit connected to the first winding 21; and the secondary side circuit 42, which is a bridge circuit connected to the second winding 22. At least one of the primary side circuit 41 and the secondary side circuit 42 has a plurality of switching elements Q1 to Q8.

[0126] According to this structure, it is not necessary to configure a resonance capacitor on both the primary side and the secondary side, and only one resonance capacitor 3 provided in the transformer 10, 10A, 10B can be used, so it is easy to achieve miniaturization of the device. In addition, according to this structure, it is only necessary to perform an insulation design that can withstand a relatively high voltage in the transformer 10, 10A, 10B, so it is easy to achieve miniaturization of the device. Therefore, according to this structure, there is an advantage that it is easy to achieve miniaturization of the power supply device 100 using the transformer 10, 10A, 10B.

[0127] Industrial Applicability

[0128] The present disclosure is useful for a power supply device or the like that steps up or down a predetermined voltage.

[0129] Description of Reference Numerals

[0130] 1: core; 11: first core; 111: leg; 12: second core; 121: leg; 13: third core; 14: fourth core; 15: fifth core; 21: first winding; 22: second winding; 23: third winding; 231: conductor pattern; 232: conductor; 3: capacitor for resonance; 41: primary side circuit; 42: secondary side circuit; 5, 5A: substrate; 51: through hole; 6: insulator; 61: through hole; 7: housing; 71: resin; 10, 10A, 10B: transformer; 100: power supply device; 200: power supply device of comparative example; 300: transformer of comparative example; 301: first winding; 302: second winding; 303: first capacitor for resonance; 304: second capacitor for resonance; G1: gap; Q1 to Q8: switching elements.

Claims

1. A transformer for unidirectional or bidirectional power conversion, wherein: The transformer has: Multiple magnetic cores; A first winding connected to the primary side circuit; a second winding connected to the secondary side circuit; Capacitors for resonance; as well as a third winding connected in series with the resonant capacitor inside the transformer to form a closed circuit, The first winding, the second winding, and the third winding are all wound around at least one magnetic core among the plurality of magnetic cores.

2. The transformer according to claim 1, wherein: The invention further comprises a substrate having a through hole penetrating in the thickness direction and into which a leg portion of any one of the plurality of magnetic cores is inserted, The third winding is formed of a conductor pattern formed on the substrate.

3. The transformer according to claim 2, wherein: The third winding is arranged inside the substrate.

4. The transformer according to claim 3, wherein: The resonance capacitor is provided inside the substrate.

5. The transformer according to claim 1, wherein: The third winding is formed by winding a conductive wire around a leg portion of any one of the plurality of magnetic cores.

6. The transformer according to any one of claims 1 to 5, wherein: The third winding and the resonance capacitor are covered with an insulating resin.

7. The transformer according to any one of claims 1 to 5, wherein: further comprising a housing for accommodating the plurality of magnetic cores, the first winding, the second winding, the third winding, and the resonance capacitor, The housing is filled with a resin having thermal conductivity.

8. A power supply device comprising: The transformer according to any one of claims 1 to 5; The primary side circuit is a bridge circuit connected to the first winding; and The secondary side circuit is a bridge circuit connected to the second winding, in, At least one of the primary-side circuit and the secondary-side circuit includes a plurality of switching elements.

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