Transformer in flyback switching power supply, CBB power supply module and air conditioner

Abstract

The invention discloses a transformer in a flyback switching power supply, a CBB power supply module and an air conditioner, and the transformer comprises a skeleton which is provided with a magnetic core installation part; the plurality of windings are sequentially wound on the framework from inside to outside, and the plurality of windings comprise a plurality of primary windings and a plurality of secondary windings; the magnetic core is mounted on the magnetic core mounting part, and the transformer is designed according to the guidance of a geometric parameter Kg = (Ku * Ac * Ac * WA) / MLT, so that the power requirement of the transformer is met by improving Ku and MLT on the small-size magnetic core; wherein Ku is the filling factor of the magnetic core window, Ac is the sectional area of the magnetic core, WA is the area of the magnetic core window, and MLT is the average length of each turn of the winding. According to the method, geometric parameters related to the size of the transformer can be used for guiding design of the transformer, and the use power requirement is met while it is ensured that the size of the transformer is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flyback switching power supply technology, and in particular to a transformer, a CBB (Circuit Board Building Block) power module and an air conditioner in a flyback switching power supply. Background Art

[0002] A switching power supply is a power supply device that converts electrical energy through high-frequency switching devices (such as transistors and MOSFETs). Its key components include switching devices, transformers, filters, and control circuits. These components work together to achieve efficient conversion of electrical energy and stable output voltage.

[0003] Existing 30W flyback switching power supplies generally operate in the 60-132kHz range. To ensure design reliability, the EER series magnetic core (such as EER28) is commonly used. However, the entire transformer is relatively large, resulting in the switching power supply occupying a large space on the circuit board, which is not conducive to the miniaturization of the power module design. Summary of the Invention

[0004] In response to the problems pointed out in the background technology, some embodiments of the present application provide a transformer in a flyback switching power supply, which uses geometric parameters related to the size of the transformer to guide the design of the transformer, ensuring that the power requirements are met while reducing the size of the transformer.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: Some embodiments of the present application relate to a transformer in a flyback switching power supply, including: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion and is used to guide the design of the transformer according to a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

[0006] This technical solution has the following beneficial effects or advantages: The transformer in the flyback switching power supply involved in the present application takes into account the entire volume of the transformer and the power demand of the transformer, and refines the key geometric parameter of the transformer Kg=(Ku*Ac*Ac*WA) / MLT. Compared with the existing AP design method, this geometric parameter adds consideration of the filling factor Ku of the core window and the average length per turn MLT of the winding. At the same time, AP=Ac*WA is considered as Ac*Ac*WA, so that the transformer can meet the power demand requirement in a small volume, reducing the volume of the transformer, thereby reducing the overall volume of the flyback switching power supply and facilitating miniaturization design.

[0007] In some embodiments of the present application, the conductor of the primary winding is an enameled wire, and the conductor of the secondary winding is a triple-insulated wire.

[0008] This technical solution has the following beneficial effects or advantages: Since the number of turns of the secondary winding is relatively large compared to the primary winding, considering the cost and the winding's compliance with safety regulations, the secondary winding's conductor uses triple-insulated wire. Compared with enameled wire, triple-insulated wire has better insulation performance, meets the primary and secondary winding safety requirements, and reduces the thickness of the insulating film between the windings, thereby reducing the volume of the transformer.

[0009] In some embodiments of the present application, the structure of the magnetic core is EFD type, EE type, or ETD type.

[0010] This technical solution has the following beneficial effects or advantages: According to the power requirements of the transformer, the existing EFD, EE, or ETD cores on the market are used to change the power size. Compared with the existing core structure with the same power in a large volume, the same power requirement can be met in a small volume, thereby reducing the area occupied by the transformer on the circuit board.

[0011] In some embodiments of the present application, the transformer is subjected to a temperature rise test and an anti-saturation capability test, and during the temperature rise test and the anti-saturation capability test, it is necessary to ensure that Kg is greater than the electrical parameter Eg of the transformer; Among them, Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R); n*Imax=Bmax*Lg / u0; Where ρ is the resistivity of copper at room temperature, n is the number of turns of the primary winding, Imax is the maximum primary current of the transformer, Bmax is the maximum magnetic induction intensity corresponding to the maximum primary current, R is the winding resistance of the transformer, L is the inductance of the transformer, u0 is the magnetic permeability of air, and Lg is the length of the air gap on the core.

[0012] This technical solution has the following beneficial effects or advantages: Considering the electrical parameter Eg of the transformer, after designing the magnetic core based on the Kg consideration, it is necessary to test the transformer performance. During the test, it is necessary to make Kg greater than Eg to ensure that the use margin is considered when designing the transformer and improve the reliability of the transformer.

[0013] Some embodiments of the present application also relate to a CBB power module, including: A housing forming the appearance of the CBB power module; a circuit substrate, located in the housing and serving as a carrier for the CBB power module; a transformer located within the housing and comprising: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion and is used to guide the design of the transformer according to a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; an output pin, which is welded to the circuit substrate and is used to output a DC power supply; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

[0014] This technical solution has the following beneficial effects or advantages: By considering the entire volume of the transformer and the power demand of the transformer, the key geometric parameter of the transformer Kg=(Ku*Ac*Ac*WA) / MLT is extracted. Compared with the existing AP design method, this geometric parameter adds the filling factor Ku of the core window and the average length per turn MLT of the winding into consideration. At the same time, AP=Ac*WA is considered as Ac*Ac*WA, so that the transformer can meet the power demand requirement in a small volume, reducing the volume of the transformer, thereby reducing the volume of the entire CBB power module and realizing the miniaturization design of the CBB power module.

[0015] In some embodiments of the present application, the conductor of the primary winding is an enameled wire, and the conductor of the secondary winding is a triple-insulated wire.

[0016] This technical solution has the following beneficial effects or advantages: Considering the cost and the winding's compliance with safety regulations, the secondary winding's conductor uses triple-insulated wire. Compared with enameled wire, triple-insulated wire has better insulation performance, meets the primary and secondary winding safety requirements, and reduces the thickness of the insulating film between the windings, thereby reducing the volume of the transformer.

[0017] In some embodiments of the present application, the structure of the magnetic core is EFD type, EE type, or ETD type.

[0018] This technical solution has the following beneficial effects or advantages: According to the power requirements of the transformer, the existing EFD, EE, or ETD cores on the market are used to change the power size. Compared with the existing core structure with the same power in a large volume, the same power requirement can be met in a small volume, thereby reducing the area occupied by the transformer on the circuit board.

[0019] In some embodiments of the present application, the transformer is subjected to a temperature rise test and an anti-saturation capability test, and during the temperature rise test and the anti-saturation capability test, it is necessary to ensure that Kg is greater than the electrical parameter Eg of the transformer; Among them, Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R), n*Imax=Bmax*Lg / u0; Where ρ is the resistivity of copper at room temperature, n is the number of turns of the primary winding, Imax is the maximum primary current of the transformer, Bmax is the maximum magnetic induction intensity corresponding to the maximum primary current, R is the winding resistance of the transformer, L is the inductance of the transformer, u0 is the magnetic permeability of air, and Lg is the length of the air gap on the core.

[0020] This technical solution has the following beneficial effects or advantages: Considering the electrical parameter Eg of the transformer, after designing the magnetic core based on the Kg consideration, it is necessary to test the transformer performance. During the test, it is necessary to make Kg greater than Eg to ensure that the use margin is considered when designing the transformer and improve the reliability of the transformer.

[0021] Some embodiments of the present application also relate to an air conditioner, comprising: an indoor unit, which is used to adjust the indoor temperature; an outdoor unit connected to the indoor unit; a wired controller connected to the indoor unit and used to control the operation of the air conditioner; A CBB power supply module is used in the power supply circuit of any one or more of the indoor unit, outdoor unit and wired controller in the air conditioner. The CBB power supply module includes a transformer, which includes: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion and is used to guide the design of the transformer according to a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; An output pin, used to provide a DC power supply to the power supply circuit; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

[0022] This technical solution has the following beneficial effects or advantages: By considering the entire volume of the transformer and the power demand of the transformer, the key geometric parameter of the transformer Kg=(Ku*Ac*Ac*WA) / MLT is extracted. Compared with the existing AP design method, this geometric parameter adds the filling factor Ku of the core window and the average length per turn MLT of the winding into consideration. At the same time, AP=Ac*WA is considered as Ac*Ac*WA, so that the transformer can meet the power demand requirement in a small volume, reducing the volume of the transformer, thereby reducing the volume of the entire CBB power module and realizing the miniaturization design of the CBB power module.

[0023] The miniaturized design of the CBB power module reduces the space it occupies on the air conditioner baseboard, facilitates the flexible arrangement of components on the baseboard, and facilitates the miniaturization design of the air conditioner electrical box.

[0024] In some embodiments of the present application, the CBB power module includes: A housing forming the appearance of the CBB power module; A circuit substrate is provided, wherein the transformer and the circuit substrate are both located in the housing, and the output pin of the transformer is welded to the circuit substrate.

[0025] This technical solution has the following beneficial effects or advantages: The modular design of the CBB power module allows for flexible use in different situations.

[0026] Other features and advantages of the present invention will become more apparent after reading the detailed description of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 This is a functional block diagram of an existing air conditioner; Figure 2 It is the main circuit of the outdoor unit of the existing air conditioner; Figure 3 How to power the outdoor unit of an existing air conditioner; Figure 4 The side view and top view of the existing EER28 type magnetic core; Figure 5 The figure shows the existing bobbin used in EER28 type magnetic core and the matching diagram between the bobbin and EER28 type magnetic core; Figure 6 This is a functional block diagram of an existing flyback transformer; Figure 7 The figure is a simplified winding diagram of an existing flyback transformer; Figure 8 It is a structural diagram of a transformer with an EER28 type magnetic core; Figure 9 The following are the side and top views of the existing EFD25 core; Figure 10 A structural diagram of a transformer with an EFD25 type magnetic core proposed in this application; Reference numerals: 100. Skeleton; 110. Skeleton top; 111. First magnetic core mounting position; 120. Skeleton base; 121. Second magnetic core mounting position; 130. Winding part; 131. Through-hole part; 200. Magnetic core; 210. Choke part; 220. Iron core part; 300. Inverter circuit; 310. Rectifier circuit; 320. PFC circuit; 330. IPM; 400. Motor. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0033] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0034] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0035] See also Figure 1 , which shows the basic principle block diagram of the air conditioner.

[0036] An air conditioner performs its refrigeration cycle by using a compressor, condenser, expansion valve, and evaporator. The refrigeration cycle involves a series of processes involving compression, condensation, expansion, and evaporation to cool or heat the indoor space.

[0037] Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, releasing heat into the surrounding environment through the condensation process.

[0038] The expansion valve expands the high-temperature, high-pressure liquid refrigerant condensed in the condenser to a lower-pressure liquid. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves cooling by utilizing the latent heat of evaporation to exchange heat with the material being cooled. Throughout this cycle, the air conditioner regulates the temperature of the indoor space.

[0039] The outdoor unit of the air conditioner refers to a portion of a refrigeration cycle including a compressor and an outdoor heat exchanger, the indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit.

[0040] The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger functions as a condenser, the air conditioner functions as a heater in heating mode, and when the indoor heat exchanger functions as an evaporator, the air conditioner functions as a cooler in cooling mode.

[0041] The outdoor unit of an air conditioner is also commonly called an outdoor unit, and the indoor unit of an air conditioner is also commonly called an indoor unit.

[0042] A flyback switching power supply is commonly used in air conditioners. It is a power supply device that converts electrical energy through high-frequency switching devices (such as transistors and MOSFETs). The DC power output by this switching power supply can be used in the power supply circuit of the outdoor unit, the power supply circuit of the indoor unit, or the power supply circuit of the wired controller.

[0043] Figure 2 Shows the main circuit of the outdoor unit. Figure 3 The schematic diagram shows the principle of a flyback switching power supply used in the power supply circuit of an outdoor unit.

[0044] Figure 2 The main circuit of the middle outdoor unit includes an inverter circuit 300 , which includes a rectifier circuit 310 , a PFC circuit 320 , a capacitor C, and an IPM (Intelligent Power Module) 330 . The IPM 330 is configured to receive the bus voltage output by the PFC circuit 320 to drive a load.

[0045] Therefore, Figure 2 For example, the rectifier circuit 310, the PFC circuit 320 and the capacitor C may constitute a main power circuit of the outdoor unit.

[0046] When powering the outdoor unit, the drive motor (for example, a compressor, an outdoor fan, etc.) is powered through the main power supply circuit (for example, a DC / DC converter), and the outdoor chip (for example, an outdoor main control chip, an outdoor communication chip) is powered through the auxiliary power supply circuit, wherein a flyback switching power supply is provided on the auxiliary power supply circuit to directly draw power from the bus.

[0047] The transformer in a flyback switching power supply can be called a flyback transformer, named because its output terminal obtains energy when the primary winding is disconnected from the power supply.

[0048] In some embodiments of the present application, the transformer is an important component of the switching power supply and occupies a major space in the switching power supply. If the volume of the transformer is reduced, the volume of the switching power supply as a whole can be reduced, facilitating miniaturization design.

[0049] In some embodiments of this application, see Figure 4 and Figure 5 , taking the EER28 type magnetic core and its adapted bobbin as an example to illustrate the structure of the transformer.

[0050] See also Figure 4 and Figure 5 The transformer includes a bobbin 100 , a plurality of windings (not shown) and a magnetic core 200 .

[0051] The frame 100 is an important component of the transformer and is used to provide a winding space for the windings, so that multiple windings of the transformer can be wound on the frame 100 .

[0052] In some embodiments of the present application, the skeleton 100 includes a skeleton top 110, a winding portion 130 and a skeleton base 120, wherein a winding space is formed between the skeleton top 110 and the skeleton base 120, and multiple windings of the transformer can be wound in the winding space on the winding portion 130.

[0053] The skeleton 100 has a core mounting portion, and the core 200 is mounted on the core mounting portion. For example, the core mounting portion includes a first core mounting position 111 located at the top 110 of the skeleton, a second core mounting position 121 located at the base 120 of the skeleton, and a through portion 131 passing through the first core mounting position 111 and the second core mounting position 121.

[0054] See also Figure 5The iron yoke portion 210 of the upper EER28 type magnetic core 200 is located at the first magnetic core mounting position 111 and its iron core portion 220 extends into one end of the through portion 131. The iron yoke portion 210 of the lower EER28 type magnetic core 200 is located at the second magnetic core mounting position 121 and its iron core portion 220 extends into the other end of the through portion 131. The contact position of the iron yoke portions 210 of the upper and lower EER28 type magnetic cores is pasted to form a closed area around the iron core portion (see Figure 5 ).

[0055] The skeleton base 120 is used to fix the transformer on a circuit substrate (not shown). In some embodiments of the present application, the transformer can be welded (such as soldering) to the circuit substrate through a metal probe (unmarked) on the skeleton base 120. For example, a plug-in slot (not shown) is provided on the circuit substrate, and the transformer can be plugged into the plug-in slot of the circuit substrate through the metal probe of the skeleton base 120, which facilitates the disassembly and maintenance of the transformer.

[0056] In some embodiments of the present application, the material of the skeleton 100 can be nylon, plastic, epoxy board, glass fiber, polytetrafluoroethylene, etc.

[0057] In some embodiments of the present application, a plurality of windings are sequentially wound on the frame 100 from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings.

[0058] The primary winding is the primary coil, which is connected to the power supply of the transformer and is used to receive electrical energy from the power supply and excite the magnetic field of the transformer; the secondary winding is also called the secondary coil, which is connected to the load of the transformer and is used to be affected by the magnetic field of the transformer and provide electrical energy to the load.

[0059] In some embodiments of the present application, by refining the parameters of the transformer, a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT is obtained, and the geometric parameter Kg is used to guide the design of the transformer so that the transformer power requirement can be met by increasing Ku and MLT on a small-volume magnetic core.

[0060] Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

[0061] As follows, we will describe the theoretical derivation process of refining the geometric parameter Kg and using it to guide the design of the transformer.

[0062] See also Figure 6 , which gives the principle block diagram of the flyback transformer.

[0063] The flyback transformer must have an air gap on the magnetic core. If the air gap is not opened, the flyback transformer will get out of control during operation and cannot work normally.

[0064] See also Figure 6 , n is the number of turns of the primary winding (representing the number of turns of the flyback transformer), Φ is the magnetic flux (unit: Weber), Rc is the resistance of the core, Lc is the effective magnetic path length of the core, Lg is the length of the air gap on the core, and Rg is the resistance of the air gap.

[0065] Where u0 is the magnetic permeability of air (4π*10 -7 H / m (henry per meter)), uc is the relative magnetic permeability of the core to air (for example, taking the commonly used PC40 ferrite core as an example, its relevant parameters can be obtained from the PC40 magnetic permeability key parameter table. For example, the relative magnetic permeability at 25°C and low field strength is 2000-2300, and the effective magnetic permeability of the equivalent magnetic field rate (related to frequency, temperature, and bias) under actual working conditions is about 800-1500), and Ac is the cross-sectional area of ​​the core.

[0066] According to the working principle of the transformer, the following formulas (1) and (2) can be obtained.

[0067] Rc=Lc / (uc*Ac) (1).

[0068] Rg=Lg / (u0*Ac) (2).

[0069] From the above data, it can be seen that during normal operation, uc is at least 1000 times larger than u0, and in general, Lg is about 60 times smaller than Lc. By comparison, Rg is more than 16 times larger than Rc. Therefore, in practical applications, Rc can be ignored.

[0070] In order to grasp its key elements, the flyback switching power supply model is further simplified. The magnetic flux Φ can be regarded as the current in the magnetic circuit, and ni can be regarded as the voltage. In this way, the entire circuit can be deduced using a method similar to Ohm's law, and the following formula (3) is obtained.

[0071] ni=Φ(Rc+ Rg) (3).

[0072] Since Rg is much larger than Rc, formula (3) is simplified to formula (4).

[0073] ni=Φ*Rg (4).

[0074] For a given winding's peak current Imax, which corresponds to the corresponding maximum magnetic induction intensity Bmax, it operates according to formula (5).

[0075] n*Imax=Bmax*Ac*Rg (5).

[0076] Substituting formula (2) into formula (5), we can obtain n*Imax=Bmax*Lg / u0 (6).

[0077] According to the known winding inductance L=n 2 / Rg, substitute formula (2) into the formula for the inductance L to obtain the following formula (7).

[0078] L=(u0*Ac*n 2 ) / Lg (7).

[0079] In some embodiments of the present application, the flyback transformer winding diagram is shown in FIG. Figure 7 .

[0080] Combine Figure 7 , confirm the actual parameters involved in the transformer.

[0081] See also Figure 7 , let the core window area be WA, the cross-sectional area of ​​the coil be AW, assuming there are n turns of winding, then the total area of ​​the coil in the core window is n*AW, in the entire core window, the window area that can be wound is Ku*WA, where Ku is the filling factor of the core window, which is always less than 1.

[0082] The total area of ​​the coil in the core window is always smaller than the window area where the wire can be wound, that is: Ku*WA>n*AW (8).

[0083] For flyback transformers, since the primary-secondary spacing needs to meet safety regulations, insulation between layers is required, and insulation of the magnetic core is required, the Ku value is generally between 0.2 and 0.3.

[0084] The core window fill factor (Ku) is the ratio of the actual winding area used within the core window to the core window area. When selecting a core, the core window fill factor (Ku) is an important parameter that affects the performance and efficiency of the transformer.

[0085] In a flyback transformer, the resistance R of the coil can be determined using the following formula (9).

[0086] It is known that R=(ρ*Lb) / AW (9).

[0087] Where Lb is the length of the coil, AW is the cross-sectional area of ​​the coil, and ρ is the resistivity of copper at room temperature, which is 1.72×10 -8 Ω·m.

[0088] The length of a coil with n turns can be expressed as n*MLT, where MLT represents the average length per turn of the winding.

[0089] Thus, formula (10) can be obtained.

[0090] R=(ρ*n*MLT) / AW (10).

[0091] In some embodiments of the present application, as mentioned above, the geometric parameters of the transformer are only related to the cross-sectional area Ac (unit: cm) of the core. 2 ), core window area WA (unit: cm 2 ), the filling factor Ku of the core window and the average length per turn MLT of the winding (in cm).

[0092] Therefore, in some embodiments of the present application, the geometric parameter Kg is obtained in combination with the above formula.

[0093] Kg=(Ku*Ac*Ac*WA) / MLT (11).

[0094] Compared with the existing AP design method (i.e., AP=Ac*WA) to obtain AP, the geometric parameter Kg increases the consideration of improving the parameters Ku and MLT, so as to fully utilize the core window and achieve the same power requirement in a small volume.

[0095] As follows, the above technical objectives will be achieved by combining existing magnetic core types and improving the geometric parameters of the transformer.

[0096] The existing transformer uses EER28 core (see Figure 5 As shown), after checking the parameters of the EER28 core, it is known that the volume is approximately 28mm*11mm*30mm=9240mm 3 .

[0097] See also Figure 8 It can be seen that the utilization rate of the EER28 core window is low. There is a 1.5mm and 3mm retaining tape at both ends of the length H direction of the bobbin 100 respectively. The winding is not full, and there is a 2.5mm gap in its width W direction.

[0098] See also Figure 8 , calculate the core window area WA1 at this time: WA1=(16.5-4.5)*(5.65-2.5) / 100=0.378cm 2 .

[0099] In some embodiments of the present application, the transformer of the present application adopts the existing EFD25 type magnetic core (see Figure 9 As shown), after checking the parameters of the EER28 core, it is known that the volume is approximately 26mm*26mm*9mm=6084mm 3 Compared with the EER28 core, the volume is effectively reduced by 34.15%.

[0100] See also Figure 10 , which gives the use of Figure 9 The EFD core shown here uses a wall-less technology to fully utilize the core window (i.e., there is essentially no gap at either end of the bobbin's length, H). The windings leave only a 0.5mm gap in its width, W. Calculate the core window area, WA2, at this point: WA2=16.5*(3.65-0.5) / 100=0.51975cm 2 .

[0101] It can be seen that after adopting the existing EFD25 type magnetic core, the core window area WA2>WA1.

[0102] It should be noted that in some embodiments of the present application, due to the large number of turns of the primary winding, enameled wire is selected, and the secondary winding is triple-insulated wire, so as to meet the primary and secondary safety requirements without using retaining wall tape.

[0103] The geometric parameter Kg obtained as above is related to the core window area WA, the core window filling factor Ku, the core cross-sectional area Ac, and the average turn length MLT.

[0104] Therefore, in some embodiments of the present application, whether the power requirement of the transformer is met after winding using a small-volume magnetic core needs to be verified.

[0105] In some embodiments of the present application, as described above, through actual comparison of using EER28 type core winding to fill the core window and using EFD25 type core winding to fill the core window, the filling factor Ku of the core window of the existing transformer is 0.2, and the filling factor Ku of the core window of the transformer involved in the present application is 0.3.

[0106] In some embodiments of the present application, the value of Ku is generally between 0.2 and 0.3, and to increase Ku, the value is selected to be greater than 0.2.

[0107] By checking the parameters of the EER28 core, we know that the core is a circle (see Figure 4 ), its diameter is 9.9mm, it can be concluded that the average length of each turn of the winding MLT = π * 9.9mm = 31.1mm, the cross-sectional area of ​​the core Ac = 82.1mm 2 .

[0108] Therefore, the geometric parameter Kg1 corresponding to the EER28 core is calculated using formula (11).

[0109] Kg1=(Ku*Ac*Ac*WA1) / MLT=0.2*82.1mm 2*82.1mm 2 *37.8 mm 2 / 31.1mm≈1638.5mm 5 .

[0110] By looking up the parameters of the EFD25 core, we know that the center of the core is similar to a rectangle (see Figure 9 ), the average length of each turn of the winding MLT = (11.4mm + 5.2mm) * 2 = 33.2mm, the cross-sectional area of ​​the core Ac = 58mm 2 .

[0111] Therefore, the geometric parameter Kg2 corresponding to the EFD25 core is also calculated using formula (11).

[0112] Kg2=(Ku*Ac*Ac*WA2) / MLT=0.3*58mm 2 *58mm 2 *51.975 mm 2 / 33.2mm≈1580mm 5 .

[0113] The two calculated geometric parameters Kg1 and Kg2 are not much different, which means that when using this geometric parameter Kg to guide the design of the transformer, it can ensure that the power requirement of the improved small-volume transformer is basically the same as the power requirement of the large-volume transformer before the improvement.

[0114] And in actual applications, they can all pass the corresponding reliability tests.

[0115] As described above, when the existing EER28 type magnetic core is used to make a transformer to achieve a 30W power usage, the transformer can be improved based on the geometric parameters proposed in this application. For example, in some embodiments of this application, the use of EFD25 type magnetic core to make a transformer can also achieve the 30W power usage requirement.

[0116] In this way, while the volume is reduced by 34.15%, the power demand of the transformer can still be met, the area occupied by the transformer is reduced, and at the same time the space occupied by the transformer on the circuit substrate is reduced, which is conducive to the miniaturization of the switching power supply.

[0117] In some embodiments of the present application, after the transformer is designed, reliability testing generally includes a temperature rise test and an anti-saturation capability test. These two tests are conventional testing methods in the field of transformer technology and will not be described in detail here.

[0118] In some embodiments of the present application, the electrical parameter Eg of the transformer is also extracted in combination with the above formula.

[0119] Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R) (12).

[0120] Where ρ is the resistivity of copper at room temperature, which is 1.72×10 -8 Ω·m, n is the number of turns of the primary winding, Imax is the maximum primary current of the transformer (unit: A (i.e., ampere)), Bmax is the maximum magnetic induction intensity corresponding to the maximum primary current (unit: T (i.e., Tesla)), R is the winding resistance of the transformer (unit: ohm), L is the inductance of the transformer (unit: H (i.e., Henry)), u0 is the magnetic permeability of air (unit: H / m (i.e., Henry per meter)), and Lg is the length of the air gap on the core (unit: mm).

[0121] Under the temperature rise test and anti-saturation capability test described above, Kg>Eg is required to ensure the transformer usage margin and improve the transformer reliability.

[0122] In some embodiments of the present application, Imax obtained according to formula (6) is substituted into formula (12) to obtain formula (13).

[0123] Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R) =ρ* Bmax*Lg*Bmax*Lg*L*L / ( u0*n* u0*n*Bmax*Bmax*R) =ρ*Lg*Lg*L*L / ( u0*n* u0*n*R) (13).

[0124] From formula (13), it can be seen that the unit of the electrical parameter Eg is also mm 5 , which corresponds to the unit of the geometric parameter Kg.

[0125] In some embodiments of the present application, according to actual use requirements, the structure of the magnetic core can be EFD type, EE type, or ETD type, etc., and there is no limitation on this type.

[0126] When users select different types of magnetic cores according to their needs, a small-sized transformer can be designed based on the geometric parameters Kg and Eg, while meeting the power requirements.

[0127] In some embodiments of the present application, a CBB (Circuit Board Building Block) power module (not shown) is also involved. The function of the CBB is to standardize devices and share materials. The CBB power module is a power conversion module with high reliability and standardized design.

[0128] Due to its modular nature, the CBB power module is convenient for use in multiple occasions, and its plug-and-play feature makes it easy to plug and unplug it on the circuit board, and easy to disassemble and connect.

[0129] In some embodiments of the present application, the CBB power module includes a housing, which forms the appearance of the CBB power module and provides it with modular characteristics.

[0130] In some embodiments of the present application, the CBB power module further includes a transformer for converting a DC power output to provide electrical energy to a load.

[0131] In some embodiments of the present application, the CBB power module further includes a circuit substrate, which is a PCB carrier board of the CBB power module, and the transformer and its peripheral circuits can be arranged on the circuit substrate.

[0132] The transformer and the circuit substrate are both placed in the housing to achieve overall modular packaging.

[0133] The transformer has an output pin, which can be a metal probe arranged on the skeleton base. In some embodiments of the present application, the transformer can be welded (such as soldering) to the circuit substrate through the metal probe. For example, a plug-in slot is provided on the circuit substrate, and the transformer can be plugged into the plug-in slot of the circuit substrate through the metal probe of the skeleton base, which facilitates the disassembly and maintenance of the transformer.

[0134] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0135] The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A transformer in a flyback switching power supply, characterized in that: include: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion, and the transformer is designed according to the geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

2. The transformer in the flyback switching power supply according to claim 1, characterized in that: The conductor of the primary winding is an enameled wire, and the conductor of the secondary winding is a triple-insulated wire.

3. The transformer in the flyback switching power supply according to claim 1, characterized in that: The structure of the magnetic core is EFD type, EE type, or ETD type.

4. The transformer in the flyback switching power supply according to claim 1, characterized in that: Performing a temperature rise test and an anti-saturation capability test on the transformer, and ensuring that Kg is greater than the electrical parameter Eg of the transformer during the temperature rise test and the anti-saturation capability test; Among them, Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R); n*Imax=Bmax*Lg / u0; Where ρ is the resistivity of copper at room temperature, n is the number of turns of the primary winding, Imax is the maximum primary current of the transformer, Bmax is the maximum magnetic induction intensity corresponding to the maximum primary current, R is the winding resistance of the transformer, L is the inductance of the transformer, u0 is the magnetic permeability of air, and Lg is the length of the air gap on the core.

5. A CBB power module, characterized in that: include: A housing forming the appearance of the CBB power module; a circuit substrate, located in the housing and serving as a carrier for the CBB power module; a transformer located within the housing and comprising: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion and is used to guide the design of the transformer according to a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; an output pin, which is welded to the circuit substrate and is used to output a DC power supply; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

6. The CBB power module according to claim 5, characterized in that: The conductor of the primary winding is an enameled wire, and the conductor of the secondary winding is a triple-insulated wire.

7. The CBB power module according to claim 5, characterized in that: The structure of the magnetic core is EFD type, EE type, or ETD type.

8. The CBB power module according to claim 5, characterized in that: Performing a temperature rise test and an anti-saturation capability test on the transformer, and ensuring that Kg is greater than the electrical parameter Eg of the transformer during the temperature rise test and the anti-saturation capability test; Among them, Eg=ρ*Imax*Imax*L*L / (Bmax*Bmax*R), n*Imax=Bmax*Lg / u0; Where ρ is the resistivity of copper at room temperature, n is the number of turns of the primary winding, Imax is the maximum primary current of the transformer, Bmax is the maximum magnetic induction intensity corresponding to the maximum primary current, R is the winding resistance of the transformer, L is the inductance of the transformer, u0 is the magnetic permeability of air, and Lg is the length of the air gap on the core.

9. An air conditioner, characterized in that: include: an indoor unit, which is used to adjust the indoor temperature; an outdoor unit connected to the indoor unit; a wired controller connected to the indoor unit and used to control the operation of the air conditioner; A CBB power supply module is used in the power supply circuit of any one or more of the indoor unit, outdoor unit and wired controller in the air conditioner. The CBB power supply module includes a transformer, which includes: A frame having a magnetic core mounting portion; A plurality of windings are wound on the frame in sequence from the inside to the outside, and the plurality of windings include a plurality of primary windings and a plurality of secondary windings; A magnetic core is mounted on the magnetic core mounting portion and is used to guide the design of the transformer according to a geometric parameter Kg=(Ku*Ac*Ac*WA) / MLT, so that the transformer power requirement is met by increasing Ku and MLT on a small-volume magnetic core; An output pin, used to provide a DC power supply to the power supply circuit; Where Ku is the filling factor of the core window, Ac is the cross-sectional area of ​​the core, WA is the core window area, and MLT is the average length per turn of the winding.

10. The air conditioner according to claim 9, characterized in that The CBB power module includes: A housing forming the appearance of the CBB power module; A circuit substrate is provided, wherein the transformer and the circuit substrate are both located in the housing, and the output pin of the transformer is welded to the circuit substrate.

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