Planar transformer, power conversion circuit, and adapter
By incorporating a noise cancellation winding in a planar transformer and optimizing the coil turns design, the problem of poor common-mode noise suppression in switching power supplies was solved, resulting in more efficient noise suppression and reduced electromagnetic interference.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUAWEI TECH CO LTD
- Filing Date
- 2020-10-28
- Publication Date
- 2026-06-16
AI Technical Summary
Existing switching power supplies have poor common-mode noise suppression performance, resulting in severe electromagnetic interference and making it difficult to meet noise suppression requirements.
Design a planar transformer comprising a primary winding, a secondary winding, and a noise cancellation winding. By setting a first noise cancellation winding between the primary and secondary windings and utilizing the coil turn design of the noise cancellation winding layer, common-mode noise cancellation or compensation can be achieved, thereby reducing the number of turns of the noise cancellation winding.
It effectively reduces the number of coil turns in the noise cancellation winding, improves noise suppression performance, reduces high-frequency eddy current loss and leakage inductance, enhances shielding effect, reduces cumulative processing tolerance, and improves noise consistency.
Smart Images
Figure CN114496523B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of circuit technology, and more particularly to a planar transformer, power conversion circuit and adapter. Background Technology
[0002] Switching power supplies have developed rapidly due to their advantages of high efficiency, small size, and good output stability. However, electromagnetic interference (EMI) during the operation of switching power supplies is a significant problem. EMI in switching power supplies mainly originates from external interference sources, the switching of internal switching devices, the directional recovery of rectifier diodes, and noise generated by capacitors, inductors, and wires. These noise signals can be conducted and radiated along the circuit network to the power-consuming equipment, causing EMI. Therefore, switching power supplies have very strict requirements for noise suppression.
[0003] Noise in switching power supplies is categorized into differential-mode noise and common-mode noise. Differential-mode noise primarily includes noise caused by the pulsating current of the switching converter. Common-mode noise mainly includes noise to ground generated by the interaction between various parameters of the switching power supply circuit. In practical engineering applications, common-mode noise is often the main cause of electromagnetic interference. Therefore, how to reduce or even eliminate common-mode noise in switching power supplies is a major concern in the industry. Summary of the Invention
[0004] This application provides a planar transformer, a power conversion circuit, and an adapter that can improve noise suppression performance.
[0005] In a first aspect, this application provides a planar transformer, including a magnetic core and a printed circuit board (PCB) winding board, wherein the PCB winding board includes: a primary winding, a secondary winding, and a first noise cancellation winding. The primary winding includes a first primary winding layer, the secondary winding includes a first secondary winding layer, and the first noise cancellation winding includes at least two noise cancellation winding layers. The coils of the noise cancellation windings in the at least two noise cancellation winding layers are connected in series to form the first noise cancellation winding. The first end of the first noise cancellation winding is used to connect to the potential static point of the secondary circuit of the power conversion circuit or to connect to the potential static point of the primary circuit of the power conversion circuit. The second end of the first noise cancellation winding is left floating. The noise cancellation winding layer where the second end of the first noise cancellation winding is located is the first noise cancellation winding layer. The first noise cancellation winding layer is disposed between the first primary winding layer and the first secondary winding layer. When the first end of the first noise cancellation winding is used to connect to the potential static point of the secondary circuit, the first noise cancellation winding layer is adjacent to the first primary winding layer. When the first end of the first noise cancellation winding is used to connect to the potential static point of the primary circuit, the first noise cancellation winding layer is adjacent to the first secondary winding layer.
[0006] In this embodiment, a first noise cancellation winding is provided between the primary and secondary windings of a planar transformer. By designing the number of turns in each noise cancellation winding layer of the first noise cancellation winding, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer can be used to cancel or compensate the induced voltage of the first secondary winding layer when the planar transformer is operating, thereby suppressing common-mode noise generated by the secondary or primary winding and improving noise suppression performance. Furthermore, since the first noise cancellation winding is formed by connecting the coils of at least two noise cancellation winding layers in series, and the first noise cancellation winding layer located between the first primary winding layer and the first secondary winding layer is the noise cancellation winding layer where the second end of the first noise cancellation winding is located, the noise cancellation winding coils of other noise cancellation winding layers connected in series with this first noise cancellation winding layer are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer. Therefore, compared with the prior art, the first noise cancellation winding layer in this application can achieve the required induced voltage using fewer coil turns.
[0007] In this application, a single noise cancellation winding layer, two layers, or multiple layers can be provided between the first primary winding layer and the first secondary winding layer; no limitation is made here. The requirement is that the first noise cancellation winding layer is positioned between the first primary winding layer and the first secondary winding layer, and that the first noise cancellation winding layer is adjacent to the first primary winding layer when its first end is used to connect to the potential rest point of the secondary circuit, and adjacent to the first secondary winding layer when its first end is used to connect to the potential rest point of the primary circuit.
[0008] In this application, the primary winding may further include a second primary winding layer; the secondary winding may further include a second secondary winding layer; and at least one second noise cancellation winding layer is further provided between the second primary winding layer and the second secondary winding layer, wherein the second noise cancellation winding layer refers to any noise cancellation winding layer other than the first noise cancellation winding layer in the first noise cancellation winding. That is, the induced voltage of the cancellation winding coil in the second noise cancellation winding layer is used to cancel or compensate the induced voltage of the second secondary winding layer, thereby further suppressing common-mode noise generated by the secondary winding or the primary winding, and thus improving noise suppression performance.
[0009] In one possible implementation, the second noise-canceling winding layer, containing the noise-canceling winding furthest from the first end, is positioned between the second primary winding layer and the second secondary winding layer, and is adjacent to both the second primary winding layer and the second secondary winding layer, respectively. This is because, among all the second noise-canceling winding layers, the second noise-canceling winding layer containing the noise-canceling winding furthest from the first end has the largest induced voltage in the noise-canceling winding. Therefore, if the same induced voltage is required, the number of turns of the coil in the second noise-canceling winding layer containing the noise-canceling winding furthest from the first end can be minimized.
[0010] In one possible implementation, if the common-mode noise to be compensated or canceled is small, the second noise cancellation winding layer where the first end is located can be disposed between the second primary winding layer and the second secondary winding layer, and adjacent to the second primary winding layer and the second secondary winding layer respectively.
[0011] Optionally, in this application, the coil turn width of the noise cancellation winding in the first noise cancellation winding layer is greater than the coil turn width of the noise cancellation winding in the second noise cancellation winding layer. That is, the coil turn width in the noise cancellation winding layer where the second end of the first noise cancellation winding is located is designed to be wider, while the coil turn width in the noise cancellation winding layer where the first end of the first noise cancellation winding is located is designed to be narrower. This can further reduce the number of coil turns in the first noise cancellation winding.
[0012] In one possible implementation, the coil turns of the noise cancellation windings in the first noise cancellation winding layer are the same.
[0013] In one possible implementation, in the first noise cancellation winding layer, the coil of the noise cancellation winding that is closer to the second end has a larger coil turn width.
[0014] Optionally, in this application, the PCB winding board further includes an auxiliary winding, which is disposed in at least one layer of the second noise cancellation winding layer. Since the second noise cancellation winding layer is mainly used to increase the induced voltage of the coil in the first noise cancellation winding layer, placing the auxiliary winding in the second noise cancellation winding layer will not affect the first noise cancellation winding layer. Furthermore, it can reduce the number of winding layers in the PCB winding board, improve the space utilization of the planar transformer, and thus save on the cost of the planar transformer.
[0015] In practice, the auxiliary winding can be any type of winding other than the noise cancellation winding, and there is no limitation here.
[0016] In this application, the relative positions of the primary and secondary windings can include at least three methods. For example, in the first method, all the primary winding layers of the primary winding can be located on one side of all the secondary winding layers of the secondary winding. Alternatively, in the second method, the secondary winding can be arranged on both sides of the primary winding; that is, a portion of the secondary winding layers can be arranged on one side of the primary winding, and another portion of the secondary winding layers can be arranged on the other side of the primary winding, forming a sandwich-like structure. Using this sandwich structure can reduce high-frequency eddy current losses and leakage inductance of the windings. Alternatively, in the third method, the primary winding can also be arranged on both sides of the secondary winding.
[0017] Secondly, this application provides a power conversion circuit comprising: a primary circuit, a secondary circuit, and any one of the planar transformers described in the first aspect, wherein the planar transformer is disposed between the primary circuit and the secondary circuit.
[0018] Thirdly, this application provides an adapter including a housing and the power conversion circuit described in the second aspect, wherein the power conversion circuit is disposed within the housing. Attached Figure Description
[0019] Figure 1 This is a schematic diagram illustrating a possible application scenario provided by an embodiment of this application;
[0020] Figure 2 This is a schematic diagram of a power conversion circuit provided in one embodiment of this application;
[0021] Figure 3 This is a schematic diagram of a power conversion circuit provided in another embodiment of this application;
[0022] Figure 4 This is a schematic diagram of a noise suppression method according to an embodiment of this application;
[0023] Figure 5 This is a cross-sectional schematic diagram of a planar transformer provided in related technologies;
[0024] Figure 6 This is a schematic diagram of the structure of a planar transformer according to an embodiment of this application;
[0025] Figure 7 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0026] Figure 8 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0027] Figure 9 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0028] Figure 10 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0029] Figure 11 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0030] Figure 12 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0031] Figure 13 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0032] Figure 14 This is a cross-sectional schematic diagram of a planar transformer according to another embodiment of this application;
[0033] Figure 15 This is a schematic diagram showing the connection relationship between the power conversion circuit and the planar transformer in an embodiment of this application;
[0034] Figure 16 This is a schematic diagram of the adapter provided in the embodiments of this application. Detailed Implementation
[0035] To make the objectives, technical solutions, and advantages of this application clearer, a further detailed description of this application will be provided below in conjunction with the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction as described in this application are illustrative based on the accompanying drawings, but changes may be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.
[0036] It should be noted that specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below. The following descriptions are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.
[0037] To facilitate understanding of the embodiments of this application, some terms involved in the embodiments of this application will be introduced first below.
[0038] Planar transformer: Unlike traditional transformers, planar transformers have a planar core and windings. The core typically uses a small-sized E-type or RM-type core structure, and the windings are generally made of multiple layers of printed circuit boards (PCBs). This design has lower DC resistance, smaller leakage inductance and distributed capacitance, a very small height, and can achieve higher operating frequencies.
[0039] Flyback converters are widely used for AC / DC and DC / DC conversion. They are common low-power switching power supply converters, characterized by their simple structure and low cost. Their core components include a power switching transistor, a transformer, diodes, and capacitors. The power switching transistor is controlled by pulse-width modulation (PWM), generating a high-frequency square wave signal in the primary winding of the transformer through its switching on and off states. This signal is then inductively coupled to the secondary winding of the transformer, achieving energy transfer. Through the filtering and rectification effects of the diodes and capacitors in the secondary circuit, a stable DC output is obtained at the output terminal.
[0040] Common-mode noise: Common-mode noise, also known as asymmetric noise or line-to-ground noise, exists in electrical equipment that uses AC power. The current of common-mode noise flows in the same direction on the two transmission lines and remains in the same phase with respect to ground, and returns through the ground wire.
[0041] Static potential point: In a circuit network, the voltage potential amplitude at a network node remains relatively constant during circuit operation, without high-frequency jumps or oscillations. For example, the filter capacitors after rectification in the primary and secondary circuits of a flyback converter; the positive or negative terminals of these capacitors and the network nodes directly connected to them are the static potential points.
[0042] Winding layer: In a planar transformer, a winding layer refers to a multi-turn coil located in the same plane within the winding. This plane is perpendicular to the central axis of the magnetic core around which the winding is wrapped. The multi-turn coils can be wound parallel to each other on the same plane, either from the inside out or from the outside in. A single winding may contain multiple winding layers, each located in a plane parallel to the others and arranged perpendicular to the central axis of the magnetic core. Correspondingly, two adjacent winding layers refer to two winding layers whose planes are parallel and do not have another winding layer in between.
[0043] This application provides a planar transformer, a power conversion circuit, and an adapter. The planar transformer can be incorporated into the power conversion circuit, and the power conversion circuit can be incorporated into the adapter.
[0044] Specifically, adapters can be used in scenarios where devices are charged or powered. For example, Figure 1 This illustrates a possible application scenario of an embodiment of this application. For example... Figure 1 As shown, this application scenario includes an external power source 11, an adapter 12, and a device 13 to be charged. For example, the device 13 to be charged may include a cellular phone, a laptop, a battery, etc., and this embodiment of the application is not limited to this. Typically, the adapter 12 can be connected to the external power source 11. The power conversion circuit included in the adapter 12 is used to convert the higher voltage provided by the external power source 11 into a lower voltage that conforms to the charging or power supply standards of the device 13 to be charged, and to charge or supply power to the device 13.
[0045] The planar transformer provided in this application embodiment can reduce noise generated during operation. This noise may include common-mode noise. The power conversion circuit may be a switching power supply converter; for example, a switching power supply converter may include the aforementioned flyback converter. Common-mode noise is mainly generated by the interaction between various parameters of the switching power supply circuit and the noise to the reference ground, which will be discussed below. Figure 2 and Figure 3 This paper introduces the mechanism of common-mode noise generation and transmission in the power conversion circuit 20.
[0046] like Figure 2 As shown, the power conversion circuit 20 typically includes a primary circuit 21, a secondary circuit 22, and a transformer 23. For example... Figure 3 As shown, the primary circuit typically includes a primary switching transistor 211 and a primary filter capacitor 212. Further, the primary circuit also includes a rectifier circuit. The aforementioned primary switching transistor 211 can also be called a power switching transistor. The secondary circuit 22 typically includes a secondary rectifier transistor 221 and a secondary filter capacitor 222. The transformer 23 includes a primary winding 231, a magnetic core, and a secondary winding 232. The primary winding 231 can be connected to the primary switching transistor 211 and the primary filter capacitor 212, and the secondary winding 232 can be connected to the secondary rectifier transistor 221 and the secondary filter capacitor 222. The primary filter capacitor 212 and the secondary filter capacitor 222 are typically electrolytic capacitors.
[0047] Normally, the node connected to either end of the primary filter capacitor 212 is the static potential point of the primary circuit; alternatively, the ground node of the primary circuit can also be the static potential point of the primary circuit. The node connected to either end of the secondary filter capacitor 222 is the static potential point of the secondary circuit.
[0048] When the power conversion circuit 20 is working, the AC power input from the external power supply 11 is rectified and filtered by the primary circuit 21, and then converted into stable high-voltage DC power, which is input to the primary winding 231 of the transformer 23. The primary switch 211 connected to the primary winding 231 couples the voltage on the primary winding 231 to the secondary winding 232 through high-frequency switching. The voltage coupled to the secondary winding 232 is rectified and filtered by the secondary circuit 22, and then outputs low-voltage DC power to the load to charge or supply power to the load. The load mentioned above is the device 13 to be charged. During the operation of the power conversion circuit 20, the primary switch 211 generates a jumping voltage Vp due to high-frequency switching, and the secondary rectifier 221 generates a jumping voltage Vs due to high-frequency switching.
[0049] Because of the parasitic capacitance between the primary winding 231 and the secondary winding 232 of the transformer, the switching voltages Vp and Vs generate common-mode noise in the power conversion circuit 20 through these parasitic capacitances. Specifically, see... Figure 3 As shown, the parasitic capacitances include the distributed capacitance Cps between the primary winding and the secondary winding, and the distributed capacitance Csp between the secondary winding and the primary winding. The switching voltage Vp in the primary circuit generates a noise current Ips flowing to ground through Cps, and the switching voltage Vs in the secondary circuit generates a noise current Isp flowing to ground through Csp. These noise currents Ips and Isp constitute the common-mode noise.
[0050] Suppressing the aforementioned common-mode noise is one of the challenges in designing highly competitive adapters in the current industry.
[0051] It should be noted that, Figure 3 The diagram also shows a Line Impedance Stabilization Network (LISN) circuit, which is a test circuit used to detect the common-mode noise current flowing to ground when the power conversion circuit is operating. In other words, the ground current detected by the LISN network can be considered equivalent to the common-mode noise generated by the power conversion circuit.
[0052] Figure 4 This is a schematic diagram illustrating noise suppression methods using related technologies. See also... Figure 4 As shown, in related technologies, a noise cancellation winding 233 is introduced into the planar transformer 23 to generate a reverse noise current. The magnitude of the reverse noise current can be adjusted by adjusting the number of turns of the noise cancellation winding 233, so that the reverse noise and the original noise can cancel each other out. Figure 5 This is a schematic cross-sectional view of the winding structure in a planar transformer, as described in related technologies. Figure 5As shown, noise cancellation winding layers B1 and B2 are respectively disposed between the primary winding 231 and the secondary winding 232, and noise cancellation winding layers B1 and B2 are respectively provided with noise cancellation windings 233 of Nb turns. One end of the noise cancellation winding 233 in each noise cancellation winding layer B1 or B2 is connected to the potential static point of the primary circuit, and the other end is left floating.
[0053] However, in practical engineering applications, the number of turns in the noise cancellation winding is generally large, about 4 turns or more. Too many turns will bring the following disadvantages: (1) The winding channel width of the noise cancellation winding layer is limited, and the maximum number of turns is limited, which may result in insufficient reverse noise current; (2) A certain processing gap needs to be reserved between the turns in the noise cancellation winding. Too many turns will result in incomplete shielding of the primary power winding by the noise cancellation winding, and the more turns there are, the worse the shielding effect will be; (3) When there are many turns in the noise cancellation winding layer, the cumulative processing tolerance is large, resulting in poor noise consistency.
[0054] To address the aforementioned problems, this application proposes a planar transformer with low common-mode noise. Power conversion circuits using this planar transformer exhibit high noise suppression performance and can reduce the number of turns in the noise cancellation winding. Furthermore, this application also provides a power conversion circuit using this planar transformer and an adapter using this power conversion circuit. Specifically, the planar transformer, power conversion circuit, and adapter can be found in [reference needed]. Figures 1 to 3 For the sake of brevity, the description in the text will not be repeated here.
[0055] The transformer provided in this embodiment mainly consists of a magnetic core and winding coils. The winding coils can be made of traditionally fired copper wire, or they can be made of a PCB winding board formed by etching multiple layers of PCB. The latter, being more flattened than the former, is generally referred to as a planar transformer. Figure 6 A schematic diagram of one structure of a planar transformer 60 is shown. (For example...) Figure 6 As shown, the planar transformer 60 includes a magnetic core 61 and a PCB winding board 62.
[0056] This application does not limit the material or shape of the magnetic core 61. For example, the shape of the magnetic core 61 can be EE type, EI type, or similar. Figure 6 The RM type is shown. The PCB winding board 62 described above can be fitted onto the magnetic post of the magnetic core 61.
[0057] like Figure 6 As shown, the PCB winding board 62 may include: a primary winding 621, a secondary winding 622, and a first noise cancellation winding 623, wherein:
[0058] In this application, the primary winding 621 refers to any winding connected to the primary circuit side, other than the first noise cancellation winding 623, and the secondary winding 622 refers to any winding connected to the secondary circuit side, other than the first noise cancellation winding 623.
[0059] The primary winding 621 may include at least one primary winding layer. Each primary winding layer included in the primary winding 621 can be represented by P1, P2, ..., PN, where N is an integer greater than 1. It should be noted that, since the cross-section of the planar transformer 60 is symmetrical, therefore, in this application... Figure 7 The diagram shown is a half-section schematic of the planar transformer 60. Similarly, in the following text... Figures 8 to 14 A schematic diagram of a half-section of a planar transformer is shown.
[0060] At least one primary winding layer Pn (n = 1 to N, any integer) may contain a primary power winding coil, or it may contain a primary auxiliary winding coil. The coils may be constructed using conductive layers. The primary power winding coils are connected in series. The primary auxiliary winding may refer to a winding in a power conversion circuit that provides a small power supply to circuits other than the main power circuit. These other circuits may include, for example, drive, control, and detection circuits.
[0061] The primary winding 621 may include a first primary winding layer, on which at least a portion of the coils of the primary power winding may be provided, or at least a portion of the coils of the primary auxiliary winding may also be provided.
[0062] The secondary winding 622 may include at least one secondary winding layer. Each secondary winding layer included in the secondary winding 622 can be represented by S1, S2, ..., SM, where M is an integer greater than 1. Similar to the primary winding 621, the coils arranged on the at least one secondary winding layer Sm (m = any integer from 1 to M) are connected in series. The at least one secondary winding layer Sm may contain a secondary power winding coil, or it may also contain a secondary auxiliary winding coil. The secondary auxiliary winding coil can be any coil other than the secondary power winding coil, and is not limited herein.
[0063] The secondary winding 622 may include a primary winding layer, on which at least a portion of the coils of the secondary power winding may be provided, or at least a portion of the coils of the secondary auxiliary winding may also be provided.
[0064] The first noise cancellation winding 623 may include at least two noise cancellation winding layers. Each noise cancellation winding layer included in the first noise cancellation winding 623 may be represented by LB1, LB2, ..., LBN.
[0065] The coils of the noise cancellation windings in the at least two noise cancellation winding layers are connected in series to form a first noise cancellation winding 623. For example, the first noise cancellation winding 623 includes a noise cancellation winding layer LB1 and a noise cancellation winding layer LB2. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 to form the first noise cancellation winding 623. The first noise cancellation winding 623 has two ends. The first end of the first noise cancellation winding 623 is used to connect to the potential static point of the secondary circuit of the power conversion circuit or to connect to the potential static point of the primary circuit of the power conversion circuit. The second end of the first noise cancellation winding 623 is left floating. The noise cancellation winding layer where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer.
[0066] It should be emphasized that: when the first end of the first noise cancellation winding 623 is used to connect to the potential static point of the secondary circuit, the first noise cancellation winding layer is disposed between the first primary winding layer Pn and the first primary winding layer Sm, and the first noise cancellation winding layer is adjacent to the first primary winding layer Pn; when the first end of the first noise cancellation winding 623 is used to connect to the potential static point of the primary circuit, the first noise cancellation winding layer is disposed between the first primary winding layer Pn and the first primary winding layer Sm, and the first noise cancellation winding layer is adjacent to the first primary winding layer Sm.
[0067] In this application, a single noise cancellation winding layer, two layers, or multiple layers can be provided between the first primary winding layer and the first secondary winding layer; no limitation is made here. The requirement is that the first noise cancellation winding layer is positioned between the first primary winding layer and the first secondary winding layer, and that the first noise cancellation winding layer is adjacent to the first primary winding layer when its first end is used to connect to the potential rest point of the secondary circuit, and adjacent to the first secondary winding layer when its first end is used to connect to the potential rest point of the primary circuit.
[0068] In practice, only a first noise cancellation winding layer is usually set between the first primary winding layer and the first secondary winding layer, and no limitation is made here.
[0069] It should be further noted that the first noise cancellation winding layer being adjacent to the first primary winding layer means that there are no other winding layers between the first noise cancellation winding layer and the first primary winding layer, and the first noise cancellation winding layer being adjacent to the first primary winding layer means that there are no other winding layers between the first noise cancellation winding layer and the first primary winding layer.
[0070] In this embodiment of the application, the second end of the first noise cancellation winding being suspended can mean that there is no electrical connection between the second end of the first noise cancellation winding and any charged conductor, or that the second end cannot form a closed loop with other components in the planar transformer or power conversion circuit.
[0071] In this embodiment, a first noise cancellation winding is provided between the primary and secondary windings of a planar transformer. By designing the number of turns in each noise cancellation winding layer of the first noise cancellation winding, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer can be used to cancel or compensate the induced voltage of the first secondary winding layer when the planar transformer is operating, thereby suppressing common-mode noise generated by the secondary or primary winding and improving noise suppression performance. Furthermore, since the first noise cancellation winding is formed by connecting the coils of at least two noise cancellation winding layers in series, and the first noise cancellation winding layer located between the first primary winding layer and the first secondary winding layer is the noise cancellation winding layer where the second end of the first noise cancellation winding is located, the noise cancellation winding coils of other noise cancellation winding layers connected in series with this first noise cancellation winding layer are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer. Therefore, compared with the prior art, the first noise cancellation winding layer in this application can achieve the required induced voltage using fewer coil turns.
[0072] Because the first noise winding layer in this application can achieve the required induced voltage using fewer coil turns, the planar transformer provided in this application can further achieve the following effects:
[0073] (1) Effectively reduce the number of coil turns of the noise cancellation winding in the first noise cancellation winding layer;
[0074] (2) Sufficient reverse noise current can be provided in the limited winding channel of the first noise cancellation winding layer with fewer noise cancellation winding turns;
[0075] (3) By reducing the number of coil turns of the noise cancellation winding in the first noise cancellation winding layer, the total spacing between turns in the first noise cancellation winding layer can be reduced, thereby improving the shielding effect between the first noise cancellation winding layer and the first primary power winding layer or the first primary power winding layer.
[0076] (4) By reducing the number of coil turns of the noise cancellation winding in the first noise cancellation winding layer, the cumulative tolerance of the processing can be reduced and the noise consistency can be improved.
[0077] In specific implementation, the relative positions of the primary winding and the secondary winding in this application can include at least the following three methods. For example, in the first method, such as... Figure 7 and Figure 8 As shown, the primary winding layers comprising the primary winding can be located on one side of the secondary winding layers comprising the secondary winding. Alternatively, in the second form, as... Figure 9 and Figure 10 As shown, the secondary winding can be arranged on both sides of the primary winding; that is, a portion of the secondary winding layer is placed on one side of the primary winding, and the other portion of the secondary winding layer is placed on the other side of the primary winding, forming a sandwich-like structure. Using this sandwich structure can reduce high-frequency eddy current losses and leakage inductance of the winding. Alternatively, in a third method, such as... Figure 11 As shown, the primary winding can also be placed on both sides of the secondary winding.
[0078] For example, such as Figure 7 As shown, the primary winding layer (P) and the secondary winding layer (S) constitute a PS layer stacked structure. The first noise cancellation winding 623 includes a noise cancellation winding layer LB1 and a noise cancellation winding layer LB2. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 to form a first noise cancellation winding 623. The first noise cancellation winding 623 has two ends. The first end of the first noise cancellation winding 623 is used to connect to the potential static point of the secondary circuit of the power conversion circuit or to connect to the potential static point of the primary circuit of the power conversion circuit. The second end of the first noise cancellation winding 623 is left floating. The noise cancellation winding layer LB1 where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer, and the other noise cancellation winding layers LB2 are the second noise cancellation winding layers. The first noise cancellation winding layer LB1 is located between the first primary winding layer P1 and the first primary winding layer S1, and is adjacent to the first primary winding layer P1 and the first primary winding layer S1, respectively.
[0079] In the above embodiments, when the planar transformer is operating, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1 of the first noise cancellation winding 623 can be used to cancel or compensate the induced voltage of the first primary winding layer S1, thereby suppressing common-mode noise generated by the secondary winding or the primary winding and improving noise suppression performance. The noise cancellation winding coils of other noise cancellation winding layers LB2 connected in series with the first noise cancellation winding layer LB1 are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1. Therefore, the first noise cancellation layer in this application can achieve the required induced voltage using fewer coil turns.
[0080] Specifically, the number of layers of the second noise cancellation winding layer in the first noise cancellation winding is not limited to one layer, but can also be multiple layers. The more layers of the second noise cancellation winding layer, the higher the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer, which in turn can reduce the number of turns of the noise cancellation winding coil in the first noise cancellation winding layer.
[0081] For example, such as Figure 8 As shown, the primary winding layer (P) and the secondary winding layer (S) constitute a PS layer stacked structure. The first noise cancellation winding 623 includes a noise cancellation winding layer LB1, a noise cancellation winding layer LB2, and a noise cancellation winding layer LB3. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2, and the other end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB3, thereby forming the first noise cancellation winding 623. The first noise cancellation winding 623 has two ends, wherein the first end of the first noise cancellation winding 623 is used to connect to the secondary winding of the power conversion circuit. The potential static point of the circuit or the potential static point of the primary circuit used to connect the power conversion circuit, the second end of the first noise cancellation winding 623 is floating; the noise cancellation winding layer LB1 where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer, the noise cancellation winding layer LB2 and the noise cancellation winding layer LB3 are both the second noise cancellation winding layers, the first noise cancellation winding layer LB1 is located between the first primary winding layer P1 and the first primary winding layer S1, and is adjacent to the first primary winding layer P1 and the first primary winding layer S1 respectively.
[0082] In the above embodiments, when the planar transformer is operating, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1 of the first noise cancellation winding 623 can be used to cancel or compensate the induced voltage of the first primary winding layer S1, thereby suppressing common-mode noise generated by the secondary winding or primary winding and improving noise suppression performance. The noise cancellation winding coils in other noise cancellation winding layers LB2 and LB3 connected in series with the first noise cancellation winding layer LB1 are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1. Therefore, the first noise winding layer in this application can achieve the required induced voltage using fewer coil turns. Furthermore, under the same conditions, to achieve the same induced voltage, the number of coil turns in the first noise winding layer in this embodiment is less than... Figure 7 The first noise winding layer has fewer coil turns.
[0083] Optionally, in this application, when the primary winding and secondary winding are configured as a sandwich-like structure, the primary winding and secondary winding will have two adjacent surfaces. As long as the primary winding and secondary winding have adjacent surfaces, common-mode noise may be generated. Therefore, in order to further suppress the common-mode noise generated by the secondary winding or the primary winding and thus improve the noise suppression performance, noise cancellation windings can be provided between adjacent primary windings and secondary windings.
[0084] For example, in this application, the primary winding further includes a second primary winding layer; the secondary winding further includes a second secondary winding layer; and at least one second noise cancellation winding layer is provided between the second primary winding layer and the second secondary winding layer, wherein the second noise cancellation winding layer refers to any noise cancellation winding layer other than the first noise cancellation winding layer in the first noise cancellation winding. That is, the induced voltage of the cancellation winding coil in the second noise cancellation winding layer is used to cancel or compensate the induced voltage of the second secondary winding layer, thereby further suppressing common-mode noise generated by the secondary winding or the primary winding, and thus improving noise suppression performance.
[0085] For example, such as Figure 9 As shown, the primary winding layer (P) and the secondary winding layer (S) constitute an SPS layer stack structure. The first noise cancellation winding 623 includes a noise cancellation winding layer LB1 and a noise cancellation winding layer LB2. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 to form a first noise cancellation winding 623. The first noise cancellation winding 623 has two ends. The first end of the first noise cancellation winding 623 is used to connect to the potential static point of the secondary circuit of the power conversion circuit or to connect to the potential static point of the primary circuit of the power conversion circuit. The second end of the first noise cancellation winding 623 is left floating. The noise cancellation winding layer LB1 where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer, and the noise cancellation winding layer LB2 is the second noise cancellation winding layer. The first noise cancellation winding layer LB1 is located between the first primary winding layer P1 and the first primary winding layer S1, and is adjacent to the first primary winding layer P1 and the first primary winding layer S1, respectively. The second noise cancellation winding layer LB2 is disposed between the second primary winding layer P2 and the second secondary winding layer S2, and is adjacent to the second primary winding layer P2 and the second secondary winding layer S2 respectively.
[0086] In the above embodiments, when the planar transformer is operating, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1 of the first noise cancellation winding 623 can be used to cancel or compensate the induced voltage of the first primary winding layer S1, thereby suppressing common-mode noise generated by the secondary winding or primary winding and improving noise suppression performance. The noise cancellation winding coil in the second noise cancellation winding layer LB2, which is connected in series with the first noise cancellation winding layer LB1, is used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1. Therefore, the first noise cancellation layer in this application can achieve the required induced voltage with fewer coil turns. Furthermore, the second noise cancellation winding layer LB2 is disposed between the second primary winding layer P2 and the second secondary winding layer S2. The induced voltage of the cancellation winding coil in the second noise cancellation winding layer LB2 cancels or compensates the induced voltage of the second secondary winding layer, further suppressing common-mode noise generated by the secondary winding or primary winding and improving noise suppression performance.
[0087] Optionally, when the first noise cancellation winding includes multiple layers of second noise cancellation winding, only one layer of second noise cancellation winding can be provided between the second primary winding layer and the second secondary winding layer. Of course, multiple layers of second noise cancellation winding can also be provided, which is not limited here.
[0088] When only one second noise-canceling winding layer is provided between the second primary winding layer and the second secondary winding layer, the second noise-canceling winding layer containing the noise-canceling winding farthest from the first end can be located between the second primary winding layer and the second secondary winding layer, and adjacent to both the second primary winding layer and the second secondary winding layer. This is because, among all the second noise-canceling winding layers, the second noise-canceling winding layer containing the noise-canceling winding farthest from the first end has the largest induced voltage in the noise-canceling winding. Therefore, if the same induced voltage is required, the number of turns of the coil in the second noise-canceling winding layer containing the noise-canceling winding farthest from the first end can be minimized. Of course, in specific implementation, the second noise cancellation winding layer that needs to be set between the second primary winding layer and the second secondary winding layer can be determined according to the magnitude of the common-mode noise that needs to be compensated or canceled. For example, if the common-mode noise that needs to be compensated or canceled is small, the second noise cancellation winding layer where the first end of the first noise cancellation winding is located can also be set between the second primary winding layer and the second secondary winding layer. This is not limited here.
[0089] It should be noted that the second noise cancellation winding layer being adjacent to the second primary winding layer and the second secondary winding layer respectively means that there are no other winding layers between the second noise cancellation winding layer and the second primary winding layer, and that there are no other winding layers between the second noise cancellation winding layer and the second secondary winding layer.
[0090] For example, such as Figure 10 As shown, the primary winding layer (P) and the secondary winding layer (S) constitute an SPS layer stack structure. The first noise cancellation winding 623 includes a noise cancellation winding layer LB1, a noise cancellation winding layer LB2, and a noise cancellation winding layer LB3. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2, and the other end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB3, thereby forming the first noise cancellation winding 623. The first noise cancellation winding 623 has two ends, wherein the first end of the first noise cancellation winding 623 is used to connect to the secondary winding of the power conversion circuit. The potential rest point of the circuit or the potential rest point of the primary circuit used to connect the power conversion circuit, the second end of the first noise cancellation winding 623 is floating; the noise cancellation winding layer LB1 where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer, the noise cancellation winding layers LB2 and LB3 are both second noise cancellation winding layers, the first noise cancellation winding layer LB1 is disposed between the first primary winding layer S1 and the first secondary winding layer P1, and is adjacent to the first primary winding layer S1 and the first secondary winding layer P1 respectively. The second noise cancellation winding layer LB2 is disposed between the second primary winding layer P2 and the second secondary winding layer S2, and is adjacent to the second primary winding layer P2 and the second secondary winding layer S2 respectively.
[0091] In the above embodiments, when the planar transformer is operating, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1 of the first noise cancellation winding 623 can be used to cancel or compensate the induced voltage of the first primary winding layer S1, thereby suppressing common-mode noise generated by the secondary winding or primary winding and improving noise suppression performance. The noise cancellation winding coils in the second noise cancellation winding layers LB2 and LB3, which are connected in series with the first noise cancellation winding layer LB1, are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1. Therefore, the first noise cancellation layer in this application can achieve the required induced voltage using fewer coil turns. The second noise cancellation winding layer LB2 is disposed between the second primary winding layer P2 and the second secondary winding layer S2. The induced voltage of the cancellation winding coil in the second noise cancellation winding layer LB2 cancels or compensates the induced voltage of the second secondary winding layer S2, further suppressing common-mode noise generated by the secondary winding or primary winding and improving noise suppression performance. Furthermore, the noise cancellation winding coil in the second noise cancellation winding layer LB3, which is connected in series with the second noise winding layer LB2, can increase the induced voltage of the noise cancellation winding coil in the second noise winding layer LB2. Similarly, the second noise winding layer LB2 can achieve the required induced voltage with fewer coil turns.
[0092] When at least two second noise-canceling winding layers are provided between the second primary winding layer and the second secondary winding layer, if the first end of the first noise-canceling winding is used to connect to the potential static point of the secondary circuit, the second noise-canceling winding layer containing the noise-canceling winding farthest from the first end can be located between the second primary winding layer and the second secondary winding layer, and adjacent to the second primary winding layer. If the first end of the first noise-canceling winding is used to connect to the potential static point of the primary circuit, the second noise-canceling winding layer containing the noise-canceling winding farthest from the first end can be located between the second primary winding layer and the second secondary winding layer, and adjacent to the second secondary winding layer.
[0093] For example, such as Figure 11As shown, the primary winding layer (P) and the secondary winding layer (S) constitute a PSP layer stack structure. The first noise cancellation winding 623 includes a noise cancellation winding layer LB1, a noise cancellation winding layer LB2, and a noise cancellation winding layer LB3. One end of the coil of the noise cancellation winding in the noise cancellation winding layer LB1 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2, and the other end of the coil of the noise cancellation winding in the noise cancellation winding layer LB2 is connected in series with one end of the coil of the noise cancellation winding in the noise cancellation winding layer LB3, thereby forming the first noise cancellation winding 623. The first noise cancellation winding 623 has two ends, wherein the first end of the first noise cancellation winding 623 is used to connect to the secondary circuit of the power conversion circuit. The potential rest point or the potential rest point of the primary circuit used to connect the power conversion circuit, the second end of the first noise cancellation winding 623 is floating; the noise cancellation winding layer LB1 where the second end of the first noise cancellation winding 623 is located is the first noise cancellation winding layer LB1, the noise cancellation winding layers LB2 and LB3 are both second noise cancellation winding layers, the first noise cancellation winding layer LB1 is disposed between the first primary winding layer P1 and the first secondary winding layer S1, and is adjacent to the first primary winding layer P1 and the first secondary winding layer S1 respectively. The second noise cancellation winding layers LB2 and LB3 are disposed between the second primary winding layer P2 and the second secondary winding layer S2.
[0094] In the above embodiments, when the planar transformer is operating, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1 of the first noise cancellation winding 623 can be used to cancel or compensate the induced voltage of the first secondary winding layer S1, thereby suppressing common-mode noise generated by the secondary winding or the primary winding and improving noise suppression performance. The noise cancellation winding coils in the second noise cancellation winding layers LB2 and LB3, which are connected in series with the first noise cancellation winding layer LB1, are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer LB1. Therefore, the first noise cancellation layer in this application can achieve the required induced voltage with fewer coil turns. The second noise cancellation winding layers LB2 and LB3 are disposed between the second primary winding layer P2 and the second secondary winding layer S2. The induced voltage of the cancellation winding coil in the second noise cancellation winding layer LB2 or LB3 cancels or compensates the induced voltage of the second secondary winding layer S2, further suppressing common-mode noise generated by the secondary winding or the primary winding and improving noise suppression performance.
[0095] As an example, with Figure 7Taking the first noise cancellation winding 623, which includes two noise cancellation winding layers LB1 and LB2, as an example, one end of the noise cancellation winding coil in noise cancellation winding layer LB1 is left floating, and the other end of the coil in noise cancellation winding layer LB1 is connected in series with one end of the noise cancellation winding coil in noise cancellation winding layer LB2. The other end of the noise cancellation winding coil in noise cancellation winding layer LB2 is connected to the potential static point of the primary circuit or secondary circuit. The working principle of this first noise cancellation winding 623 is as follows:
[0096] Assume the induced voltage of each turn of the coil in the planar transformer is V0, the capacitance of the noise cancellation winding in the noise cancellation winding layer LB1 relative to the adjacent secondary winding is Cc1, the number of turns of the noise cancellation winding in the noise cancellation winding layer LB1 is Nb1, the capacitance of the noise cancellation winding in the noise cancellation winding layer LB1 relative to the adjacent secondary winding is Cc2, and the number of turns of the noise cancellation winding in the noise cancellation winding layer LB1 is Nb2.
[0097] In existing technology, the two noise cancellation winding layers are independent of each other, with one end connected to a static potential point and the other end floating. Calculate the reverse noise charge Q1 generated by the noise cancellation winding:
[0098] The average induced voltage of the noise cancellation winding is: V1=(0+Nb1*V0) / 2+(0+Nb2*V0) / 2=V0(Nb1+Nb2) / 2;
[0099] Reverse noise current: i1=c*dv / dt;
[0100] Reverse noise charge: Q1=i1*t=Cc1*Nb1*V0 / 2+Cc2*Nb2*V0 / 2;
[0101] Based on the scheme of this application, the reverse noise charge Q2 generated by the charge cancellation winding is calculated:
[0102] The average induced voltage of the noise cancellation winding is: V2=(0+Nb1*V0) / 2+(Nb1*V0+Nb2*V0) / 2=V0(2Nb1+Nb2) / 2;
[0103] Reverse noise current: i2=c*dv / dt;
[0104] Reverse noise charge: Q2=i2*t=Cc1*Nb1*V0 / 2+Cc2*(Nb1*n+Nb2*V0) / 2;
[0105] With the same number of turns configuration for noise cancellation windings, the noise cancellation winding of this application in series structure is compared with the existing noise cancellation winding in parallel structure:
[0106] When Nb1=Nb2=Nb and Cc1=Cc2=Cc, then we have:
[0107] Q1 = Cc * Nb * n;
[0108] Q2 = Cc * Nb * n * 3 / 2;
[0109] Therefore, it can be seen that, compared with the prior art, the noise cancellation winding of this application generates 1.5 times the reverse noise charge under the same noise cancellation winding turn configuration. Furthermore, it can be deduced that, to generate the same amount of reverse noise charge, the number of turns in the noise cancellation winding of this application can be reduced by 50%.
[0110] Furthermore, in this application, such as Figures 12 to 14 As shown, the coil turn width of the noise cancellation winding in the first noise cancellation winding layer LB1 is greater than that of the noise cancellation winding in the second noise cancellation winding layer LB2. That is, the coil turn width in the noise cancellation winding layer where the second end of the first noise cancellation winding 623 is located is designed to be wider, while the coil turn width in the noise cancellation winding layer where the first end of the first noise cancellation winding 623 is located is designed to be narrower. This can further reduce the number of coil turns in the first noise cancellation winding. The working principle of the first noise cancellation winding in the above embodiment is explained below in conjunction with the principle:
[0111] Assume the induced voltage of each turn in the transformer is V0. The first terminal of the first noise cancellation winding is connected to the static potential point of the primary or secondary circuit. The voltage of the first turn connected to the first terminal is V0. Starting from the first turn connected to the first terminal, the turns are sequentially defined as the 2nd turn, 3rd turn, ..., nth turn. Since each turn is connected in series, the induced voltage of the nth turn is nV0. Therefore, the further away from the first terminal (or closer to the second terminal), the higher the induced voltage. Thus, if the turn width of the coil closer to the second terminal is larger, the parasitic capacitance between this part of the noise cancellation winding and the adjacent secondary or primary winding is larger, resulting in more reverse noise charge generated by this part of the noise cancellation winding. Therefore, with the number of turns in the noise cancellation winding remaining constant, increasing the turn width can obtain more reverse noise charge. Similarly, given a certain amount of reverse noise charge, the number of turns in the noise cancellation winding can be further reduced.
[0112] In one possible implementation, such as Figure 12 As shown, the coil turns of the noise cancellation winding in the first noise cancellation winding layer LB1 are the same.
[0113] In one possible implementation, such as Figure 13As shown, in the first noise cancellation winding layer LB1, the coil of the noise cancellation winding that is closer to the second end has a larger coil turn width.
[0114] Optionally, in this application, such as Figure 14 As shown, the PCB winding board 62 also includes an auxiliary winding 624, which can be disposed in at least one layer of the second noise cancellation winding layer. Since the second noise cancellation winding layer is mainly used to increase the induced voltage of the coil in the first noise cancellation winding layer, placing the auxiliary winding 624 in the second noise cancellation winding layer will not affect the first noise cancellation winding layer. Furthermore, it can reduce the number of winding layers in the PCB winding board 62, improve the space utilization of the planar transformer, and thus save on the cost of the planar transformer.
[0115] In specific implementation, the auxiliary winding 624 can be any type of winding other than the noise cancellation winding, and is not limited here.
[0116] Figure 15 This is a schematic diagram showing the connection relationship between the power conversion circuit 50 and the planar transformer 60 in an embodiment of this application. Figure 15 As shown, the primary circuit 51 includes a primary switching transistor 511, a primary filter capacitor 512, and a rectifier circuit. The secondary circuit 52 includes a secondary rectifier transistor 521 and a secondary filter capacitor 522. The primary filter capacitor 512 and the secondary filter capacitor 522 can be electrolytic capacitors. Typically, the node connected to either end of the primary filter capacitor 512 is the static potential point of the primary circuit; alternatively, the ground node of the primary circuit can also be the static potential point. The node connected to either end of the secondary filter capacitor 522 is the static potential point of the secondary circuit.
[0117] like Figure 15 As shown, one end of the primary winding 621 is connected to the primary potential resting point of the power conversion circuit 50. One end of the secondary winding 622 is connected to the secondary potential resting point of the power conversion circuit. For example, the two ends of the primary winding 621 can be connected to the primary switching transistor 511 and the primary filter capacitor 512, respectively, and the two ends of the secondary winding 622 can be connected to the secondary rectifier transistor 521 and the secondary filter capacitor 522, respectively. The first end of the first noise cancellation winding 623 is electrostatically connected to the potential resting point of the primary circuit or the potential resting point of the secondary circuit of the power conversion circuit 50, and the second end of the first noise cancellation winding 623 can be left floating. "Floating" means that the second end of the first noise cancellation winding 623 has no electrical connection with any conductor and no electrical connection with any component. For example, the first end of the first noise cancellation winding 623 can be connected to the primary filter capacitor 512.
[0118] Reference Figure 16 This application also provides an adapter 100, which may include a housing 101 and a power conversion circuit 50 disposed within the housing 101. Since the principle by which this adapter solves the problem is similar to that of the aforementioned power conversion circuit, the implementation of this adapter can refer to the implementation of the aforementioned power conversion circuit, and the repeated parts will not be described again.
[0119] The planar transformer, power conversion circuit, and adapter provided in this application embodiment have a first noise cancellation winding disposed between the primary and secondary windings of the planar transformer. By designing the number of turns in each noise cancellation winding layer of the first noise cancellation winding, the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer can be used to cancel or compensate the induced voltage of the first secondary winding layer when the planar transformer is operating, thereby suppressing common-mode noise generated by the secondary or primary winding and improving noise suppression performance. Furthermore, since the first noise cancellation winding is formed by connecting the coils of at least two noise cancellation winding layers in series, and the first noise cancellation winding layer disposed between the first primary winding layer and the first secondary winding layer is the noise cancellation winding layer where the second end of the first noise cancellation winding is located, the noise cancellation winding coils of other noise cancellation winding layers connected in series with this first noise cancellation winding layer are used to increase the induced voltage of the noise cancellation winding coil in the first noise cancellation winding layer. Therefore, compared with the prior art, the first noise cancellation winding layer in this application can achieve the required induced voltage using fewer coil turns.
[0120] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0121] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0122] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0124] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0125] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A planar transformer, characterized by Includes a magnetic core and a printed circuit board (PCB) winding board, wherein the PCB winding board includes: Primary winding, including the first primary winding layer; Secondary winding, including the primary winding layer; The first noise cancellation winding includes at least two noise cancellation winding layers, and the coils of the noise cancellation windings in the at least two noise cancellation winding layers are connected in series to form the first noise cancellation winding. The first end of the first noise cancellation winding is used to connect to the potential static point of the secondary circuit of the power conversion circuit or to connect to the potential static point of the primary circuit of the power conversion circuit, and the second end of the first noise cancellation winding is left floating. The noise cancellation winding layer where the second end of the first noise cancellation winding is located is the first noise cancellation winding layer. The first noise cancellation winding layer is disposed between the first primary winding layer and the first secondary winding layer. When the first end of the first noise cancellation winding is used to connect the potential static point of the secondary circuit, the first noise cancellation winding layer is adjacent to the first primary winding layer. When the first end of the first noise cancellation winding is used to connect the potential static point of the primary circuit, the first noise cancellation winding layer is adjacent to the first secondary winding layer. The noise cancellation winding layers other than the first noise cancellation winding layer in the first noise cancellation winding are the second noise cancellation winding layers. The number of layers in the second noise cancellation winding layers is inversely proportional to the number of turns of the coil of the noise cancellation winding in the first noise cancellation winding layer. There are multiple second noise cancellation winding layers. The second noise cancellation winding layer where the noise cancellation winding farthest from the first end is located has the fewest turns of the coil of the noise cancellation winding.
2. The planar transformer of claim 1, wherein, The primary winding also includes a second primary winding layer; The secondary winding also includes a second secondary winding layer; At least one second noise cancellation winding layer is disposed between the second primary winding layer and the second secondary winding layer.
3. The planar transformer of claim 2, wherein, The second noise cancellation winding layer, where the noise cancellation winding furthest from the first end is located, is disposed between the second primary winding layer and the second secondary winding layer, and is adjacent to the second primary winding layer and the second secondary winding layer, respectively.
4. The planar transformer of claim 2, wherein, The second noise cancellation winding layer where the first end is located is disposed between the second primary winding layer and the second secondary winding layer, and is adjacent to the second primary winding layer and the second secondary winding layer respectively.
5. The planar transformer according to any one of claims 1 to 4, wherein The coil turn width of the noise cancellation winding in the first noise cancellation winding layer is greater than the coil turn width of the noise cancellation winding in the second noise cancellation winding layer.
6. The planar transformer of claim 5, wherein, The coil turns of the noise cancellation windings in the first noise cancellation winding layer are the same.
7. The planar transformer of claim 5, wherein, In the first noise cancellation winding layer, the coil of the noise cancellation winding that is closer to the second end has a larger coil turn width.
8. The planar transformer according to any one of claims 1 to 4, wherein The PCB winding board also includes an auxiliary winding, which is disposed on at least one second noise cancellation winding layer.
9. The planar transformer according to any one of claims 1 to 4, wherein The primary winding is disposed on both sides of the secondary winding, or the secondary winding is disposed on both sides of the primary winding.
10. A power conversion circuit, characterized by, include: The primary circuit, the secondary circuit, and the planar transformer as described in any one of claims 1 to 9, wherein the planar transformer is disposed between the primary circuit and the secondary circuit.
11. An adapter, characterized by It includes a housing and a power conversion circuit as described in claim 10, wherein the power conversion circuit is disposed within the housing.