Transformer and its manufacturing method, charging device and power supply device

Abstract

A transformer according to the present disclosure comprises a primary winding and a secondary winding, and is provided with a first core and a second core through which the primary winding and the secondary winding are passed and which are opposed to each other. The first core includes a single first core portion, and the second core includes a plurality of second core portions. The first core is a lower core, and the second core is an upper core. The first core and the second core are disposed opposite each other via a gap. The first core and the second core may be adhered to each other and disposed opposite each other. Alternatively, the first core and the second core may be fixed to each other by an adhesive tape in a state of being disposed opposite each other. The transformer further comprises a cooling device provided under the first core.

Description

Technical Field

[0001] The present disclosure relates to a transformer, a charging device using the transformer, a power supply device using the transformer, and a method for manufacturing the transformer, which are used in a power conversion circuit such as a DC-DC converter, for example.

Background Art

[0002] Conventionally, in electric vehicles and plug-in hybrid vehicles, an in-vehicle charging device for charging a rechargeable battery from a commercial AC power supply is mounted. For example, it is disclosed in Patent Document 1 and Patent Document 2. Here, Patent Document 1 discloses a transformer in which E-cores are combined vertically. Further, Patent Document 2 discloses a transformer in an external iron type transformer, in which inner legs are divided from the center and a heat dissipation plate is interposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the transformers of Patent Documents 1 and 2, there is a problem that core cracking occurs due to temperature change.

[0005] An object of the present disclosure is to provide a transformer that can avoid core cracking even when a temperature change occurs, a charging device using the transformer, and a power supply device using the transformer.

Means for Solving the Problems

[0006] The transformer according to this disclosure has a primary winding and a secondary winding, and comprises a first core and a second core that are inserted through the primary winding and the secondary winding and are arranged to face each other, The first core includes one first core portion, The second core includes a plurality of second core parts. It is characterized by the following: [Effects of the Invention]

[0007] According to the transformer relating to this disclosure, core cracking can be avoided even when temperature changes occur, thereby increasing the reliability of the transformer. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing an example of the configuration of an in-vehicle charging device 101 according to the present disclosure. [Figure 2] Figure 1 is a circuit diagram showing an example configuration of the LLC resonant DC-DC converter 105. [Figure 3] Figure 2 is a perspective view showing the external appearance of transformer 206. [Figure 4A] This is a longitudinal cross-sectional view along the line A-A' in Figure 3. [Figure 4B] This is a cross-sectional view of the line B-B' in Figure 3. [Figure 5] This is a magnified vertical cross-sectional view showing the strain that occurs in the core when a temperature difference occurs between the upper and lower cores of a conventional transformer. [Figure 6] This is a longitudinal cross-sectional view of the transformer 206 in Figure 1 when it is fixed with adhesive 404. [Figure 7A] This is a longitudinal cross-sectional view of the transformer 206 in Figure 2 when it is fixed with adhesive tape 701. [Figure 7B] This is a longitudinal cross-sectional view of the transformer 206 in Figure 2, when the entire circumference is fixed with adhesive tape 701. [Figure 7C] Figure 2 is a perspective view showing the appearance of the transformer 206 when its entire circumference is fixed with adhesive tape 701. [Figure 8]A longitudinal sectional view when a heat-resistant elastic body 801 is interposed between core portions 303a and 303b of the U-shaped core of the transformer 206 in FIG. 2 and fixed with an adhesive tape 701. [Figure 9] A longitudinal sectional view when a heat-resistant elastic body 901 is interposed between core portions 303a and 303b of the two U-shaped cores of the transformer 206 in FIG. 2 and the lower core 302 of the E-shaped core and fixed with an adhesive tape 701. [Figure 10] A longitudinal sectional view showing a configuration example of a transformer 206A according to Modification 1, which is composed of one I-shaped core 302A and two U-shaped cores 303Aa and 303Ab. [Figure 11] A longitudinal sectional view showing a configuration example of a transformer 206B according to Modification 2, which is composed of one T-shaped core 302B and two L-shaped cores 303Ba and 303Bb. [Figure 12A] A longitudinal sectional view showing the first process in the manufacturing process of the transformer 206 in FIG. 6. <000007%]] [Figure 12B] A longitudinal sectional view showing the second process in the manufacturing process of the transformer 206 in FIG. 6. [Figure 12C] A longitudinal sectional view showing the third process in the manufacturing process of the transformer 206 in FIG. 6. [Figure 12D] A longitudinal sectional view showing the fourth process in the manufacturing process of the transformer 206 in FIG. 6. [Figure 12E] A longitudinal sectional view showing the fifth process in the manufacturing process of the transformer 206 in FIG. 6. [Figure 13A] A longitudinal sectional view showing the first process in the manufacturing process of the transformer 206 in FIG. 7C. [Figure 13B] A longitudinal sectional view showing the second process in the manufacturing process of the transformer 206 in FIG. 7C. [Figure 13C] A longitudinal sectional view showing the third process in the manufacturing process of the transformer 206 in FIG. 7C. [Figure 13D] A longitudinal sectional view showing the fourth process in the manufacturing process of the transformer 206 in FIG. 7C. [Figure 13E]It is a longitudinal sectional view showing the fifth process in the manufacturing process of the transformer 206 in FIG. 7C. [Figure 14] It is a perspective view showing the appearance of a configuration example of a transformer 206C according to Modification 3, which is composed of a lower core 302 of one U-shaped core and an upper core 303 of an E-shaped core in which the upper core 303 is divided into four core parts 303a, 303b, 303c, and 303d. **[Embodiments for Carrying Out the Invention]**

[0009] Hereinafter, embodiments of the present disclosure will be described based on the drawings.

[0010] (Problems of the Comparative Example) Hereinafter, the transformer disclosed in Patent Document 1 is referred to as Comparative Example 1, and the transformer disclosed in Patent Document 2 is referred to as Comparative Example 2, and these problems will be described.

[0011] In a transformer in which E-shaped cores are combined vertically as in Comparative Example 1, due to a rapid temperature change such as a heat cycle test, the core in the longitudinal direction of the E-shaped core is arranged on the outermost side, and it expands or contracts according to the coefficient of thermal expansion of the core following the temperature change. Here, the inner legs located inside the core have a large volume and are located inside, so the temperature change is delayed, and due to the delay from the expansion or contraction in the longitudinal direction of the E-shaped core, core cracking occurs at the center of the core, and the reliability decreases.

[0012] Further, when a transformer in which the inner legs are divided from the center is applied to a leakage built-in transformer in which a gap is provided in the inner legs as in Comparative Example 2, the manufacturability deteriorates, and the balance of the lower surface that mainly serves as the cooling surface and further the adhesion of the connection between the cores of the outer legs cannot be maintained, the stability of the inductance value and the cooling performance of the core are impaired, and the reliability of the transformer operation decreases.

[0013] (Embodiment) Embodiments relating to this disclosure that solve the above problems are described below. However, the configurations described below are merely examples of this disclosure, and this disclosure is not limited to the embodiments described below. Various modifications are possible depending on the design, etc., even in embodiments other than these, as long as they do not deviate from the technical idea relating to this disclosure.

[0014] Figure 1 is a block diagram showing an example configuration of an on-board charging device 101 according to an embodiment of the present disclosure. The on-board charging device 101 in Figure 1 is characterized by converting AC power from a commercial AC power source 102 into DC power and outputting it to a rechargeable battery 106, and isolating the power before and after the conversion by a transformer 206 built into a DC-DC converter 105.

[0015] In Figure 1, the on-board charging device 101 is configured to include a rectifier and smoothing circuit 103, a power factor correction circuit (PFC circuit) 104, and a DC-DC converter 105. In electric vehicles or plug-in hybrid vehicles, AC power from a 100V or 200V commercial AC power source 102 is rectified and smoothed by the rectifier and smoothing circuit 103. Next, the PFC circuit 104 corrects the power factor of the input rectified and smoothed voltage and suppresses harmonics before outputting it to the DC-DC converter 105. The DC-DC converter 105 converts the input DC voltage so that it becomes a DC output voltage corresponding to the battery voltage of the subsequent rechargeable battery 106.

[0016] Figure 2 is a circuit diagram showing an example configuration of the DC-DC converter 105 in Figure 1. In this embodiment, as an example, an LLC resonant DC-DC converter 105, which is widely used in high-efficiency power supplies such as industrial switching power supplies, automotive charging devices, and power converters, is used as the DC-DC converter.

[0017] In Figure 2, the LLC resonant DC-DC converter 105 is configured with an inverter circuit 201, a resonant capacitor 209, a transformer 206, a rectifier circuit 210, a smoothing capacitor 211, and a control circuit 220 that generates gate signals Sg1 to Sg4 to control the operation of the inverter circuit 201, between the input terminals T1 and T2 and the output terminals T3 and T4. Here, the inverter circuit 201 is configured by connecting switching elements, such as N-channel MOS transistors 202 to 205, in a bridge configuration, and converts a DC voltage to an AC voltage by turning the MOS transistors 202 to 205 on or off according to the gate signals Sg1 to Sg4. The transformer 206 is configured with a leakage inductance 207, an excitation inductance 208 of the primary winding, and an inductance 212 of the secondary winding.

[0018] In the DC-DC converter 105, the inverter circuit 201 converts the input voltage into an AC voltage by switching it, and outputs it to the rectifier circuit 210 via the resonant capacitor 209 and the transformer 206. Here, the output voltage is changed using a frequency modulation method that changes the switching frequency of the four MOS transistors 202-205 by utilizing the resonance of the two inductances and one capacitor of the transformer 206 (leakage inductance 207 and excitation inductance 208) and the resonant capacitor 209. Next, the output voltage from the transformer 206 is rectified by the rectifier circuit 210, smoothed by the smoothing capacitor 211, and then a DC voltage is output.

[0019] With the DC-DC converter 105 configured as described above, switching losses are reduced by zero-voltage switching, and surge currents and voltages are reduced by a switching current that is close to a sine wave, thereby reducing noise.

[0020] Figure 3 is a perspective view showing the external appearance of the transformer 206 in Figure 2, Figure 4A is a longitudinal section view along the line A-A' in Figure 3, and Figure 4B is a transverse section view along the line B-B' in Figure 3. In Figures 3, 4A, and 4B, the top, bottom, left, and right directions are explained as the top, bottom, left, and right directions, but this is not intended to limit the usage of the transformer 206. As shown in Figure 3, the manufactured transformer 206 is mounted on an air-cooled or water-cooled cooling device 305.

[0021] In Figures 3 and 4A, the transformer 206 is composed of a lower core 302 which is an E-shaped core and constitutes a single core section, two upper core sections 303a and 303b which are U-shaped cores, and a bobbin 301 which is formed between the lower core 302 and the upper core 303 and inserted into the closed magnetic circuit region 403 formed by the lower core 302 and the upper core 303. Here, a primary winding 401 and a secondary winding 402 are wound around each groove of the bobbin 301 such that the central axis of the closed magnetic circuit region 403 becomes the winding axis. In this embodiment, each core 302 and 303 is made of, for example, a ferrite core. The bobbin 301 is made of, for example, an insulating material such as polyphenylene sulfide resin.

[0022] The lower core 302 is composed of an E-type core consisting of two outer legs 302a and 302b, one inner leg 302c, and a bottom surface 302d for supporting them. Here, the inner leg 302c is positioned to pass through the closed magnetic circuit region 403. The closed magnetic circuit region 403 penetrates horizontally in a direction parallel to the core end face.

[0023] The upper core 303 is composed of a core portion 303a of a U-shaped core and a core portion 303b of a U-shaped core. Core portion 303a consists of outer legs 303aa, inner legs 303ab, and a bottom surface portion 303ac for supporting them. Core portion 303b consists of outer legs 303ba, inner legs 303bb, and a bottom surface portion 303bc for supporting them.

[0024] Each core portion 303a and core portion 303b of the upper core 303 is arranged to face the lower core 302 as follows. (1) The end faces of the outer legs 303aa of the core portion 303a face the end faces of the outer legs 302a of the lower core 302 and are arranged to be bonded to each other with adhesive. (2) The end faces of the outer legs 303ba of the core portion 303b face the end faces of the outer legs 302b of the lower core 302 and are arranged to be bonded to each other with adhesive. (3) The end faces of the inner legs 303ab of the core portion 303a and the inner legs 303bb of the core portion 303b are spaced apart by a predetermined gap 405 and are arranged to face the end face of the inner leg 302c of the lower core 302. (4) The two core portions 303a and 303b are spaced apart from each other by a predetermined gap 406 and are arranged to face each other in the lateral direction.

[0025] Here, the inner legs 302c of the lower core 302, which is inserted into the closed magnetic circuit region 403, and the inner legs 303ab and 303bb of the two core sections 303a and 303b, which are inserted into the closed magnetic circuit region 403 of the upper core 303, are spaced apart and facing each other with a gap 405, as described above. By adjusting the spacing of this gap 405, the excitation inductance 208 that constitutes the resonant frequency of the LLC resonant DC-DC converter 105 can be adjusted. In addition, the leakage inductance 207 is adjusted by the distance between the primary winding 401 and the secondary winding 402, and here it is adjusted by the thickness of the bobbin between the primary winding 401 and the secondary winding 402, the difference in the number of turns in the upper and lower grooves of the two-stage primary winding 401, and similarly the difference in the number of turns in the upper and lower grooves of the two-stage secondary winding 402.

[0026] Furthermore, in the upward-facing cross-section of Figure 4B, it can be seen that the outer legs 303aa, 303ba and the inner legs 303ab, 303bb protrude downward from the bottom portions 303ac, 303bc, respectively, and that closed magnetic circuit regions 403 are formed between the outer leg 303aa and the inner leg 303ab, and between the outer leg 303ba and the inner leg 303bb. The closed magnetic circuit regions 403 are filled with a filler material 403A, which is made of an insulating material such as silicone filler, at the end of the manufacturing process of the entire core. At that time, the filler material 403A may also be placed in the gaps 405 and 406.

[0027] Note that the lead wires, bobbin cover to ensure insulation distance between the core and windings, and mechanism for positioning the bobbin and core, which are typically found in transformers, are not shown in the drawings, but may be added as appropriate.

[0028] Furthermore, the on-board charging device 101 is equipped with a cooling device 305 (Figure 3), such as a water cooling system or an air cooling system, to dissipate heat and cool each component. The cooling device 305 is located below the transformer 206 and dissipates the heat generated by the transformer 206. At this time, the flatness of the bottom surface of the lower core 302 greatly affects the heat dissipation. Normally, when each core 302, 303 generates heat, the lower core 302 is cooled by the cooling device 305, the upper core 303 dissipates heat less efficiently than the lower core 302, the upper core 303 is hotter than the lower core 302, and a temperature difference occurs between the upper and lower cores 302, 303.

[0029] Figure 5 is a magnified vertical cross-sectional view showing the strain generated in each core 302 and 303 when a temperature difference occurs between the upper core 303 and 303 of a conventional transformer in which the upper core 303 is not divided into two parts. Figure 5 shows a magnified view of the analysis results of the strain generated in the cores 302 and 303 when a temperature difference occurs between the upper and lower cores 302 and 303 in the conventional E-type core. Here, the bobbin 301, primary winding 401, and secondary winding 402 are not shown.

[0030] As is clear from Figure 5, the upper core 303 deforms upward convex due to the thermal expansion coefficient of the core 303, and tensile stress is applied outward. This can also be seen from the fact that the thickness of the inner legs of the upper core 303, which was the same size at the same temperature, is thicker than the thickness of the inner legs of the lower core 302, as indicated by reference numeral 303p. When such stress is applied, core cracking may occur in conventional E-type cores, but as in the configuration of this embodiment, the stress is released by separating the core portion 303a and the core portion 303b of the U-type core, making it possible to reduce core cracking.

[0031] Many passive components for automotive applications must comply with tests set by the Automotive Electronics Council (AEC), one of which is a heat cycle test, requiring resistance to rapid temperature changes. In conventional upper and lower E-shaped cores, the inner legs, located inside the core, have a large volume and their internal location causes a delay in temperature changes. This delay in expansion or contraction in the longitudinal direction of the outer E-shaped core can lead to core cracking in the center of the core. However, by dividing the upper core 303 into two core sections 303a and 303b of a U-shaped core, as in the configuration of this embodiment, the volume of the inner legs is reduced. Furthermore, the gap between the U-shaped cores allows ambient heat to be more easily transferred to the inner legs, making core cracking less likely. In addition, even if stress occurs, the division in the center reduces the stress, making core cracking less likely.

[0032] In this embodiment, the LLC resonant DC-DC converter 105 has a gap 405 (Figure 4A) in its transformer 206, which necessitates ingenuity in the actual manufacturing method. In particular, when bonding the outer legs of the upper core 303 and the lower core 302, if an epoxy adhesive 404 is used, as shown in Figure 4A, the adhesive 404 may peel off due to the gap 405, or an unintended gap may be formed between the outer legs (303aa, 302a) (303ba, 302b) of the upper core 303 and the lower core 302, resulting in a decrease from the desired inductance.

[0033] Figure 6 is a longitudinal cross-sectional view of the transformer 206 in Figure 1 when it is fixed with adhesive 404.

[0034] To solve the above problems, as shown in Figure 6, when bonding, the top and bottom of the transformer 206 are reversed, with the upper core 303, consisting of two U-shaped cores 303a and 303b, positioned on the upper side, while the lower core 302 is positioned on the lower side. The outer legs (303aa, 302a) (303ba, 302b) of the upper core 303 and lower core 302 are then fixed together with adhesive 404, thereby achieving the desired configuration.

[0035] Furthermore, since the inner legs of the upper core 303 and lower core 302 in Figure 5 are separated by a gap, there is a difference in the deformation of the inner leg thickness between the upper and lower cores. If these are fixed together, stress will be generated on cores 302 and 303 in a way that resists the deformation so that they do not follow each other. In other words, if the outer legs of the upper core 303 and lower core 302 are not fixed together with adhesive 404, the stress on the cores can be further relieved. For this reason, a method of fixing with adhesive tape can be considered, but if there is a gap 405, it may be difficult to wrap the adhesive tape around in the form shown in Figure 4A, etc.

[0036] Figure 7A is a longitudinal cross-sectional view of the transformer 206 in Figure 2 when it is fixed with adhesive tape 701. Figure 7B is a longitudinal cross-sectional view of the transformer 206 in Figure 2 when its entire circumference is fixed with adhesive tape 701, and Figure 7C is a perspective view showing the appearance of the transformer 206 in Figure 2 when its entire circumference is fixed with adhesive tape 701. Here, adhesive tape 701 is an insulating fixing tape for fixing electrical components, such as DuPont Kapton® tape.

[0037] To solve the above problems, when fixing with adhesive tape 701, as shown in Figure 7A, the adhesive tape 701 is placed on the flat surface 601a of the mounting base 601, the transformer 206 is turned upside down, and the core portions 303a and 303b of the upper core 303, which consists of two U-shaped cores, are placed on the lower side and fixed on the adhesive tape 701. Next, the bobbin 301 on which the primary winding 401 and secondary winding 402 are wound is inserted into the closed magnetic circuit region 403 of the upper core 303 and placed there. Finally, the lower core 302 is placed on top, and finally the entire core is fixed by wrapping adhesive tape 701 around it, thereby realizing the desired configurations of Figures 7B and 7C.

[0038] Figure 8 is a longitudinal cross-sectional view of the transformer 206 in Figure 2, where a heat-resistant elastic material 801 is interposed between the core portions 303a and 303b of the two U-shaped cores and fixed with adhesive tape 701.

[0039] A gap 405 is interposed between the core portions 303a and 303b of the two U-shaped cores. As shown in Figure 8, a heat-resistant elastic material 801 with insulating properties may be interposed in the gap 405, and the transformer 206 may be inverted vertically as in Figure 7 and fixed with adhesive tape 701. This allows the heat-resistant elastic material 801 to absorb the stress caused by the temperature difference between the upper core 303 and the lower core 302, making it possible to construct a stable transformer structure. The heat-resistant elastic material 801 is, for example, a so-called gap filler in the shape of a sheet, and is made of an insulating resin such as silicone resin.

[0040] Figure 9 is a longitudinal cross-sectional view of the transformer 206 in Figure 2, where a heat-resistant elastic material 901 is interposed between the core portions 303a and 303b of the two U-shaped cores and the lower core 302 of the E-shaped core, and fixed with adhesive tape 701.

[0041] Furthermore, as shown in Figure 9, a heat-resistant elastic body 901 with insulating properties is interposed in the gap 405, and a stable transformer structure can be constructed by reversing the top and bottom of the transformer 206 as in Figure 7 and fixing it with adhesive tape 701. The heat-resistant elastic body 901 is, for example, a so-called gap filler in the shape of a sheet, and is made of an insulating resin such as silicone resin. The heat-resistant elastic body 801 in Figure 8 and the heat-resistant elastic body 901 in Figure 9 may be formed together.

[0042] As described above, the transformer 206 according to this embodiment reduces stress on the upper core 303 by dividing the upper core 303 into two parts and constructing the lower core 302 with an E-shaped core. This reduces the delay in temperature change of the inner legs even with rapid temperature changes due to the U-shaped cores, preventing core cracking. Even when a gap 406 is placed between the inner legs, the flatness of the lower core surface is maintained, improving heat dissipation from the lower core surface, while improving the contact between the outer legs of the cores, thereby improving electrical stability such as inductance and the manufacturability of the transformer. This improves reliability.

[0043] (Variation 1) Figure 10 is a longitudinal cross-sectional view showing an example of the configuration of transformer 206A according to Modification 1, which consists of one I-shaped core 302A and two U-shaped cores 303Aa and 303Ab.

[0044] The core configuration of the embodiment has been composed of one E-shaped core and two U-shaped cores facing it, but as shown in Modification 1 of Figure 10, it may also be composed of one I-shaped core 302A and two U-shaped cores 303Aa and 303Ab facing it. Here, the U-shaped core 303Aa is composed of an outer leg 303Aaa, an inner leg 303Aab, and a bottom surface portion 303Aac that supports them. The U-shaped core 303Ab is composed of an outer leg 303Aba, an inner leg 303Abb, and a bottom surface portion 303Abc that supports them.

[0045] In the modified example 1 configured as described above, heat dissipation and core stress relaxation can be achieved, similar to the embodiment. Furthermore, since the gap 405 is located at the bottom end faces of the inner legs 303Aab and 303Abb, the leakage flux 1001 generated in the gap 405 is far from the primary winding 401 and secondary winding 402. The leakage flux 1001 links with the primary winding 401 and secondary winding 402, and the resulting eddy current losses can also be reduced.

[0046] (Modification 2) Figure 11 is a longitudinal cross-sectional view showing an example of the configuration of transformer 206B according to modified example 2, which consists of one T-shaped core 302B and two L-shaped cores 303Ba and 303Bb.

[0047] In the modified example 2 of Figure 11, the core configuration may consist of one T-shaped core 302B and two L-shaped cores 303Ba and 303Bb facing it. Here, the T-shaped core 302B is configured with an inner leg 302Bb and a bottom surface portion 302Ba that supports it. The L-shaped core 303Ba is configured with an outer leg 303Bab and a bottom surface portion 303Baa that supports it. Furthermore, the L-shaped core 303Bb is configured with an outer leg 303Bbb and a bottom surface portion 303Bba that supports it.

[0048] Modification 2, configured as described above, has the same effects and advantages as Modification 1.

[0049] Next, the manufacturing process for the transformer 206 shown in Figures 6 and 7C will be described below.

[0050] (Example of a manufacturing process 1) Figures 12A to 12E are longitudinal cross-sectional views showing each process in the manufacturing process of transformer 206 shown in Figure 6.

[0051] As shown in Figure 12A, the core portions 303a and 303b of the upper core 303, which consists of two U-shaped cores, are placed on the flat surface 601a of the mounting base 601 and fixed downwards. Next, as shown in Figure 12B, the bobbin 301, around which the primary winding 401 and secondary winding 402 are wound, is inserted into the closed magnetic circuit region 403 of the upper core 303. Furthermore, as shown in Figure 12C, adhesive 404 is applied to the end faces of the outer legs 303aa and 303ba of the core portions 303a and 303b. Next, as shown in Figure 12D, the lower core 302 is placed over the upper core 303 so that the end faces of the outer legs 302a and 302b of the lower core 302 face the end faces of the outer legs 303aa and 303ba of the core portions 303a and 303b, respectively, thereby bonding and fixing the lower core 302 to the upper core 303. Finally, as shown in Figure 12E, the transformer, which is a composite of the lower core 302 and the upper core 303, is inverted, the transformer 206 is placed in a predetermined case (not shown), the filler 403A is poured in and hardened, the filler 403A is filled into each of the closed magnetic circuit regions 403, the bobbin 301 is fixed, and the transformer 206 for the purpose of manufacture is obtained. Here, since the transformer 206 generates heat not only from the upper and lower cores 302 and 303 but also from the windings 401 and 402, the entire transformer 206 is housed in a predetermined case, and the inside of the case is filled with potting made of silicone resin or the like, so that the windings 401 and 402 and the upper and lower cores 302 and 303 dissipate heat to the lower cooling device 305, etc. via the potting.

[0052] (Example of manufacturing process 2) Figures 13A to 13E are longitudinal cross-sectional views showing each process in the manufacturing process of transformer 206 shown in Figure 7C.

[0053] As shown in Figure 13A, the adhesive tape 701 is fixed onto the flat surface 601a of the mounting base 601. Then, as shown in Figure 13B, the core portions 303a and 303b of the upper core 303, which consists of two U-shaped cores, are placed on the adhesive tape 701 with the core portions 303a and 303b facing downwards. Next, as shown in Figure 13C, the bobbin 301, around which the primary winding 401 and secondary winding 402 are wound, is inserted into the closed magnetic circuit region 403 of the upper core 303. Then, the lower core 302 is placed over the bobbin 302 so that the end faces of the outer legs 302a and 302b of the lower core 302 face the end faces of the outer legs 303aa and 303ba of the core portions 303a and 303b, respectively. Finally, as shown in Figure 13D, the outer legs and bottom periphery of the combined lower core 302 and upper core 303 are fixed using adhesive tape 701. After that, the combined transformer is inverted, the transformer 206 is placed in a predetermined case (not shown), the filler 403A is poured in and hardened, and the filler 403A is filled into each of the closed magnetic circuit regions 403, and the bobbin 301 is fixed to obtain the transformer 206 for manufacturing. Here, since the transformer 206 generates heat not only from the upper and lower cores 302 and 303 but also from the windings 401 and 402, the entire transformer 206 is housed in a predetermined case, and the inside of the case is filled with potting made of silicone resin or the like, so that the windings 401 and 402 and the upper and lower cores 302 and 303 dissipate heat to the lower cooling device 305, etc. via the potting.

[0054] (Variation 3) Figure 14 is a perspective view showing an example of the configuration of a transformer 206C according to Modification 3, which consists of a lower core 302 of a single U-shaped core and an upper core 303 made up of four E-shaped core cores 303a, 303b, 303c, and 303d.

[0055] In Figure 14, the upper core 303 is divided into four core sections 303a, 303b, 303c, and 303d, each having a rectangular end face shape. Here, gaps 406 and 406 are interposed between core section 303a and core section 303b, and between core section 303c and core section 303d, respectively. In addition, gaps 407 and 407 are interposed between core section 303a and core section 303c, and between core section 303b and core section 303d, respectively.

[0056] In the embodiment shown in Figure 3, the stress in the direction of the A-A' line is relieved by the gap 406. In contrast, the modified example 3 has the unique effect of not only relieving the stress in the direction of the A-A' line by the gaps 406, 406, but also relieving the stress in the direction perpendicular to the A-A' line by the gaps 407, 407.

[0057] In modification 3, the upper core 303 is divided into four parts, but for example, the upper core 303 may be divided into three parts at 120-degree intervals centered on the central part of the transformer 206. Similarly, the upper core 303 may be divided into five or more parts centered on the central part of the transformer 206.

[0058] (Other variations) In the embodiments described above, the primary winding 401 is the upper winding and the secondary winding 402 is the lower winding. However, the disclosure is not limited to this, and similar effects can be obtained by swapping them, or by arranging the primary winding 401 and the secondary winding 402 on the inside and outside of the inner leg, or by reversing them.

[0059] The primary winding 401 and secondary winding 402 may be copper wire, Litz wire, or triple insulated winding wire (TIW). Industrial application fields

[0060] The transformers 206, 206A, 206B, and 206C relating to this disclosure are not limited to the DC-DC converter 105 of the charging device 101 in Figure 1 that supplies a charging voltage to the rechargeable battery 106, but can also be used in various power supply devices that supply a predetermined power supply voltage to a load. [Explanation of symbols]

[0061] 101 On-vehicle charging device 102 Commercial AC power supply 103 Rectifier and smoothing circuit 104 Power factor correction circuit (PFC circuit) 105 DC-DC Converter 106 rechargeable batteries 201 Inverter Circuit 202-205 MOS transistors 206, 206A, 206B, 206C transformers 207 Leakage Inductance 208 Excitation Inductance 209 Resonant Capacitor 210 Rectifier circuit 211 Smoothing Capacitor 212 Inductance 220 Control circuits 301 Bobbin 302 Lower core (core part) 302a,302b external leg 302c inner leg 302d bottom part 302A Type I core (core section) 302B T-type core (core part) 302Ba bottom part 302Bb Inner leg 303 Upper core (core part) 303a, 303b, 303c, 303d U-shaped core (core part) 303aa,303ba external leg 303ab,303bb Inner leg 303ac,303bc bottom part 303Aa, 303Ab U-shaped core (core part) 303Aaa,303Aba external leg 303Aab,303Abb Inner leg 303Aac,303Abc bottom part 303Ba, 303Bb L-shaped core (core part) 303Baa,303Bba Bottom part 303Bab,303Bbb Outer leg 305 Cooling device 401 Primary winding 402 Secondary winding 403 Closed magnetic circuit area 403A Filler 404 Adhesive 405 Gap 406 Gap 407 Gap 601 Mounting platform 601a flat surface 701 Adhesive Tape 801 Heat-resistant elastic material 901 Heat-resistant elastic material 1001 Leakage flux T1~T4 terminals

Claims

1. A transformer having a primary winding and a secondary winding, and comprising a first core and a second core arranged so as to pass through the primary winding and the secondary winding and face each other, The first core includes one first core portion, The second core includes a plurality of second core portions, The second core is configured to allow the primary winding and the secondary winding, which are wound on a single bobbin, to be inserted through it. The first core portion is an E-type core, Each of the second core sections is a U-shaped core, The second core portions are arranged relative to each other via a heat-resistant elastic material. transformer.

2. Further comprising a cooling device provided below the first core, The transformer according to claim 1.

3. A transformer having a primary winding and a secondary winding, and comprising a first core and a second core arranged so as to pass through the primary winding and the secondary winding and face each other, The first core includes one first core portion, The second core includes a plurality of second core portions, The second core is configured to allow the primary winding and the secondary winding, which are wound on a single bobbin, to be inserted through it. The first core portion is an E-type core, Each of the second core sections is a U-shaped core, The system further comprises a cooling device located below the first core. transformer.

4. The first core is the lower core, The second core is the upper core. A transformer according to any one of claims 1 to 3.

5. The first core and the second core are arranged to face each other with a gap in between. A transformer according to any one of claims 1 to 4.

6. The first core and the second core are arranged facing each other, with a heat-resistant elastic material included in the gap between them. The transformer according to claim 5.

7. The first core and the second core are bonded to each other and arranged to face each other. A transformer according to any one of claims 1 to 6.

8. The first core and the second core are positioned facing each other and are fixed to each other with adhesive tape. A transformer according to any one of claims 1 to 6.

9. A charging device that supplies a charging voltage to a rechargeable battery, A transformer comprising the transformer described in any one of claims 1 to 8, Charging device.

10. A power supply device that supplies power voltage to a load, A transformer comprising the transformer described in any one of claims 1 to 8, power supply.

11. A method for manufacturing a transformer having a primary winding and a secondary winding, and comprising a first core and a second core, The steps include inserting the primary winding and the secondary winding, which are wound on a single bobbin, into the second core, which includes a plurality of second core portions, The steps include arranging the two core portions relative to each other via a heat-resistant elastic material, The process includes the step of inserting the first core through the primary winding and the secondary winding so that the first core faces the second core, The first core is an E-type core, Each of the second core sections is a U-shaped core. A method for manufacturing transformers.

12. Further comprising the step of arranging a cooling device below the first core, A method for manufacturing a transformer according to claim 11.

13. A method for manufacturing a transformer having a primary winding and a secondary winding, and comprising a first core and a second core, The steps include inserting the primary winding and the secondary winding, which are wound on a single bobbin, into the second core, which includes a plurality of second core portions, The steps include inserting the first core through the primary winding and the secondary winding so that the first core faces the second core, The process includes the step of placing a cooling device below the first core, The first core is an E-type core, Each of the second core sections is a U-shaped core. A method for manufacturing transformers.

14. The step of arranging the first core to face the second core is: This includes arranging the first core and the second core so that they are bonded to each other and facing each other. A method for manufacturing a transformer according to any one of claims 11 to 13.

15. The step of arranging the first core to face the second core is: The first core and the second core are fixed to each other with adhesive tape while being positioned facing each other. A method for manufacturing a transformer according to any one of claims 11 to 13.

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