Magnetic device and circuit containing magnetic device

Abstract

The present invention provides a magnetic device and a circuit including the magnetic device. The magnetic device includes a current input terminal, a current output terminal, and at least two windings connected in parallel between the current input terminal and the current output terminal. The at least two windings are interlaced and wound around a magnetic core, with the current flow direction of the winding being opposite to that of the adjacent winding. The present invention can reduce eddy current losses in the magnetic device.

Description

Technical Field

[0001] The embodiments of the present invention relate to electromagnetic technology, and in particular to a magnetic device and a circuit including the magnetic device. Background Art

[0002] In today's society, electronic products across all industries rely on switching power supplies. As a highly efficient power supply, switching power supplies have attracted considerable attention. Transformers, inductors, and other magnetic components are essential components of switching power supplies.

[0003] Windings are a crucial component of magnetic devices. According to the magnetic field strength formula (H = Ni, where i represents the current, N represents the number of winding turns, and H represents the magnetic field strength), a given number of winding turns will generate a magnetic field. Given a constant current, the greater the number of winding turns, the greater the magnetic field strength. With a large number of winding turns, magnetic field strength becomes a significant concern, as it directly affects the operating characteristics of windings, a phenomenon known in the industry as the "proximity effect."

[0004] For two adjacent windings, for example, winding A and winding B, when current I is injected in the same direction, the magnetic field generated by the current in winding A will induce a current I in winding B. A-B , current I A-B The currents are in opposite directions to the current I, in order to cancel the current I A-B , winding B will generate a reverse magnetic field, thereby inducing a current I B-A , current I B-A The current direction is the same as the current I. B-A This causes the magnetic field intensity generated by the current in winding B to continuously increase, thereby generating larger eddy current losses. Summary of the Invention

[0005] The present invention provides a magnetic device and a circuit comprising the magnetic device, so as to reduce eddy current loss of the magnetic device.

[0006] In a first aspect, an embodiment of the present invention provides a magnetic device, comprising: a current input end, a current output end, and at least two windings connected in parallel between the current input end and the current output end, wherein the at least two windings are wound alternately on a magnetic core, and the current flow direction of the winding is opposite to the current flow direction of its adjacent winding.

[0007] In a possible implementation manner, the magnetic core is a ring-shaped structure.

[0008] In a second aspect, an embodiment of the present invention provides a circuit comprising the magnetic device according to any one of the first aspects, the circuit further comprising an AC power supply, a diode, a MOS transistor, a controller, a first resistor, and a first capacitor, wherein:

[0009] The current input terminal of the magnetic device is connected to the AC power supply through a rectifier bridge;

[0010] The current output end of the magnetic device is connected to the input end of the diode and the drain of the MOS tube respectively;

[0011] The output end of the diode is connected to one end of the first capacitor and the load respectively, and the other end of the first capacitor is grounded;

[0012] The source of the MOS transistor is connected to the first input terminal of the controller and one end of the first resistor, respectively. The other end of the first resistor is grounded. The controller is used to generate a first control signal according to the voltage input through the first input terminal, and output the first control signal to the gate of the MOS transistor through the output terminal of the controller. The first control signal is used to control the on / off of the MOS transistor.

[0013] In a possible implementation, the circuit further includes a second resistor and a filter circuit, wherein:

[0014] One end of the second resistor is connected to the output end of the diode, and the other end of the second resistor is connected to the second input end of the controller. The controller is used to generate a second control signal according to the voltage input through the second input end, and output the second control signal to the gate of the MOS transistor through the output end of the controller. The second control signal is used to control the on / off of the MOS transistor.

[0015] The filter circuit has one end connected to the second input end of the controller and the other end grounded.

[0016] In a possible implementation, the filter circuit includes a third resistor and a second capacitor connected in parallel.

[0017] In a possible implementation, the first capacitor is a BULK capacitor.

[0018] In a third aspect, an embodiment of the present invention provides a circuit comprising the magnetic device according to any one of the first aspects, the circuit further comprising an AC power supply, a diode, a MOS transistor, a controller, and a first capacitor, wherein:

[0019] The drain of the MOS tube is connected to the AC power supply through a rectifier bridge;

[0020] The source of the MOS tube is connected to the current input terminal of the magnetic device and the output terminal of the diode respectively;

[0021] The current output end of the magnetic device is connected to one end of the first capacitor and the load respectively, and the other end of the first capacitor is grounded;

[0022] The input end of the diode is connected to the input end of the controller. The controller is used to generate a control signal according to the voltage input through the input end and output the control signal to the gate of the MOS tube. The control signal is used to control the on / off of the MOS tube.

[0023] In a possible implementation, the circuit further includes a first resistor and a filter circuit, wherein:

[0024] One end of the first resistor is connected to the current output end of the magnetic device, and the other end of the first resistor is connected to the input end of the controller;

[0025] The filter circuit has one end connected to the input end of the controller and the other end connected to the ground.

[0026] In a possible implementation, the filter circuit includes a second resistor and a second capacitor connected in parallel.

[0027] In a possible implementation, the first capacitor is a BULK capacitor.

[0028] The present invention provides a magnetic device and a circuit incorporating the magnetic device. The magnetic device includes a current input terminal, a current output terminal, and at least two windings connected in parallel between the current input terminal and the current output terminal. The at least two windings are interlaced around a magnetic core, and the current flow direction of the winding is opposite to that of the adjacent winding. By setting the current flow direction of adjacent windings in the magnetic device in opposite directions, eddy current losses in the magnetic device are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only 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 work.

[0030] Figure 1 A schematic diagram illustrating the proximity effect in a conventional magnetic device;

[0031] Figure 2 A schematic structural diagram of a magnetic device provided in one embodiment of the present invention;

[0032] Figure 3 A schematic diagram of the proximity effect in a magnetic device provided by one embodiment of the present invention;

[0033] Figure 4A schematic structural diagram of a magnetic device provided in another embodiment of the present invention;

[0034] Figure 5 A schematic structural diagram of a circuit provided in one embodiment of the present invention;

[0035] Figure 6 A schematic structural diagram of a circuit provided in another embodiment of the present invention;

[0036] Figure 7 for Figure 6 The equivalent circuit diagram of the circuit structure shown is when the MOS tube is turned on;

[0037] Figure 8 for Figure 6 The equivalent circuit diagram of the circuit structure shown in the figure is when the MOS tube is turned off;

[0038] Figure 9 A schematic structural diagram of a circuit provided in yet another embodiment of the present invention;

[0039] Figure 10 A schematic structural diagram of a circuit provided in yet another embodiment of the present invention;

[0040] Figure 11 for Figure 10 The equivalent circuit diagram of the circuit structure shown is when the MOS tube is turned on;

[0041] Figure 12 for Figure 10 The equivalent circuit diagram of the circuit structure shown is when the MOS tube is in the off state. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "upper," "upper," "lower," "front," "rear," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In the description of the present invention, "plurality" means two or more, unless otherwise specifically specified.

[0044] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected," "connected," and "connected" should be understood in a broad sense. For example, they may refer to a fixed connection, a connection through an intermediary medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] The terms "first", "second", etc. (if any) in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other units that are not clearly listed or that are inherent to these products or devices.

[0046] The description includes reference to the accompanying drawings, which form a part of the detailed description. The accompanying drawings show diagrams according to exemplary embodiments. These embodiments, which may also be referred to herein as "examples," are described in sufficient detail to enable those skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be used, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable those skilled in the art to practice, make, and / or use the subject matter.

[0047] First, some technical terms and existing magnetic devices involved in the present invention are explained to introduce the concept of the present invention.

[0048] Eddy current loss refers to the energy loss caused by induced currents within a conductor when it moves in a non-uniform magnetic field or is exposed to a time-varying magnetic field. The closed loops of current lines formed within a conductor are called eddy currents (also known as Foucault currents).

[0049] Figure 1 A schematic diagram showing the proximity effect in a conventional magnetic device. Figure 1 In the figure, there are three blocks A, B, and C, which can actually represent three windings in parallel, and they are injected with current I in the same direction. A , I B , I C, its direction is from "outside the paper" to "inside the paper". According to "Faraday's law of electromagnetic induction", the current I A The generated magnetic field will induce a current I in block B A-B , its direction is from "inside the paper" to "outside the paper"; according to "Lenz's law", in order to offset the current I A-B Block B will generate a reverse magnetic field, thereby inducing a current I B-A , its direction is from "outside the paper" to "inside the paper", and the current I A The same direction.

[0050] Similarly, for block C, the same phenomenon occurs, but it is affected by blocks A and B at the same time, so it will generate a current I C-B and current I C-A The induction is used to offset the electromagnetic influence of blocks A and B.

[0051] It can be seen from this that when the number of windings increases further, this phenomenon will become more serious. By the nth layer of winding, n-1 currents with the same direction as the input current will be induced.

[0052] Since the current I B-A , current I C-B and current I C-A The direction of the start-up current is the same as that of the injection current, which causes the magnetic field intensity generated by the current in the corresponding winding to increase continuously, thereby causing the winding to generate larger eddy current losses.

[0053] Furthermore, eddy current loss can lead to serious heating of the windings and other problems. In addition, due to the superposition of magnetic field strength, the external radiation intensity of the magnetic field increases. For occasions required by electromagnetic compatibility, this phenomenon will aggravate electromagnetic radiation.

[0054] Based on the above problems, the present invention provides a magnetic device and a circuit including the magnetic device, which reduces the influence of the proximity effect by setting the current flow directions of adjacent windings in the magnetic device to opposite directions, thereby reducing the eddy current loss of the magnetic device.

[0055] The magnetic device includes: a current input end, a current output end, and at least two windings connected in parallel between the current input end and the current output end. The at least two windings are wound alternately on a magnetic core, and the current flow direction of the winding is opposite to the current flow direction of its adjacent winding.

[0056] The magnetic device provided by the present invention can be applied to circuits or devices including the magnetic device, such as switching power supplies.

[0057] The magnetic device and the circuit including the magnetic device provided by the present invention are explained below with reference to specific embodiments.

[0058] Figure 2 This is a schematic diagram of the structure of a magnetic device provided by an embodiment of the present invention. Figure 2 The magnetic device provided in this embodiment includes: a current input terminal 11, a current output terminal 12, and two windings connected in parallel between the current input terminal 11 and the current output terminal 12: a winding 13 and a winding 14. The two windings are alternately wound on a magnetic core 19, and the current flow direction of the winding 13 is opposite to the current flow direction of the winding 14.

[0059] It should be noted that Figure 2 Two windings are used as an example for illustration, but the present invention is not limited thereto, and the number of windings needs to be set according to actual needs.

[0060] exist Figure 2 , the winding 13 and the winding 14 have the same winding direction, wherein the winding 13 uses the port 15 as the current inlet and is wound along the magnetic core 19 to the port 17, and the port 17 is the current outlet of the winding 13; the winding 14 uses the port 16 as the current inlet and is wound along the magnetic core 19 to the port 18, and the port 18 is the current outlet of the winding 14.

[0061] Among them, the current is injected from the current input terminal 11 and injected into the winding 13 and the winding 14 through the port 15 and the port 16 respectively, as shown in FIG. Figure 2 As shown, the current directions of the two windings are alternating and flowing in opposite directions.

[0062] Figure 3 The figure shows the proximity effect of a two-wire interlaced coil. Figure 1 For comparison with the effects shown in FIG, this embodiment still takes a three-turn winding as an example. Figure 3 According to the staggered winding method, the current directions of the two adjacent windings are opposite, so the directions of the current injected into blocks A, B, and C are: I A From "outside the paper" to "inside the paper", I B From "inside the paper" to "outside the paper", I C It is from "outside the paper" to "inside the paper".

[0063] According to Faraday's law of electromagnetic induction, the current I A The generated magnetic field induces a current I in block B A-B , its direction is from "inside the paper" to "outside the paper"; according to "Lenz's law", block B will generate a reverse magnetic field to offset the current I A-B However, the direction of the current in block B is from "inside the paper" to "outside the paper", so its own current can offset the current I A The induced current I A-B .

[0064] For block C, its own current I C It can offset the current induced by the adjacent block B, and finally block C will only induce a current I C-A Used to offset the current I in block A A The induced current I A-C .

[0065] From the above analysis, it can be seen that the use of reverse current and staggered winding methods can greatly reduce the induced current generated by adjacent windings, thereby reducing the magnetic field strength generated by the windings, achieving the purpose of reducing eddy current losses and electromagnetic interference.

[0066] In this embodiment, the magnetic device includes a current input terminal, a current output terminal, and at least two windings connected in parallel between the current input terminal and the current output terminal. The at least two windings are interlaced around a magnetic core, and the current flow direction of the winding is opposite to that of the current flow direction of the adjacent winding. By setting the current flow direction of adjacent windings in the magnetic device in opposite directions, eddy current losses in the magnetic device are reduced.

[0067] Furthermore, the above structure can also achieve the effect of reducing the loss of magnetic components; in addition, it can also reduce the intensity of the magnetic field while reducing the radiation intensity, thereby improving electromagnetic interference.

[0068] Figure 4 This is a schematic diagram of the structure of a magnetic device provided by another embodiment of the present invention. Figure 4 The magnetic device provided in this embodiment includes: a current input terminal 41, a current output terminal 42, and two windings connected in parallel between the current input terminal 41 and the current output terminal 42: a winding 43 (indicated by a solid line) and a winding 44 (indicated by a dotted line). The two windings are alternately wound on a magnetic core 45, and the current flow direction of the winding 43 is opposite to the current flow direction of the winding 44.

[0069] During the winding process, windings 43 and 44 are wound in parallel until the winding is complete. When connecting, the incoming wire end of winding 43 is connected to the outgoing wire end of winding 44 and then to the current input terminal 41; the outgoing wire end of winding 43 is connected to the incoming wire end of winding 44 and then to the current output terminal 42.

[0070] Figure 4 The direction of current injection is also indicated. When current is injected into current input terminal 41, it flows through the winding and out through current output terminal 42. This creates an effect where the currents in windings 43 and 44 flow in opposite directions, as indicated by the arrows on the windings. As can be seen from the above analysis, this effect reduces eddy current losses in magnetic components.

[0071] In this embodiment, the magnetic core 45 is an annular structure, so the magnetic device can also be called an annular magnetic device. The function of the magnetic core 45 is to store the magnetic field generated by the winding when the power is on and provide a path for the magnetic field to move.

[0072] It should be noted that the magnetic device is an inductor as an example, but the magnetic device provided by the present invention is not limited to an inductor. Since the input and output of the windings in the ring magnetic device are on the same side, this facilitates the use of the staggered winding method.

[0073] Next, an example is given to illustrate the application of the magnetic device provided by the present invention. In the following embodiment, the magnetic device functions as an inductor, and the application of the inductor in a power factor correction (PFC) circuit is given.

[0074] Application 1

[0075] Figure 5 This is a schematic diagram of the structure of a circuit provided by an embodiment of the present invention. Figure 5 The circuit provided in this embodiment includes: the magnetic device 51 as described above, an AC power supply 52, a diode 53, a MOS transistor 54, a controller 55, a first resistor 56 and a first capacitor 57.

[0076] The current input end of the magnetic device 51 is connected to the AC power supply 52 through the rectifier bridge 58; the current output end of the magnetic device 51 is respectively connected to the input end of the diode 53 and the drain of the MOS transistor 54; the output end of the diode 53 is respectively connected to one end of the first capacitor 57 and the load, and the other end of the first capacitor 57 is grounded; the source of the MOS transistor 54 is respectively connected to the first input end of the controller 55 and one end of the first resistor 56, and the other end of the first resistor 56 is grounded. The controller 55 is used to generate a first control signal based on the voltage input through the first input end, and output the first control signal to the gate of the MOS transistor 54 through the output end of the controller 55. The first control signal is used to control the on / off of the MOS transistor 54.

[0077] Specifically, in this circuit, the functions of each component are as follows:

[0078] Magnetic device 51, used for storing and releasing energy;

[0079] AC power supply 52, for providing AC power;

[0080] MOS transistor 54, used to control the storage and release of energy of the magnetic device 51;

[0081] Diode 53 is used for rectification to make the output a positive voltage;

[0082] The first capacitor 57 is used to maintain the output voltage VDC of the circuit constant, which is equivalent to gathering energy;

[0083] The first resistor 56 is used to convert the current flowing through the MOS transistor 54 into a voltage and transmit the voltage to the controller 55 to prevent overcurrent in the MOS transistor 54 .

[0084] In an exemplary embodiment, Figure 6 As shown, in Figure 5 Based on the circuit structure shown, the circuit can also include a second resistor 61 and a filter circuit 62. One end of the second resistor 61 is connected to the output end of the diode 53, and the other end of the second resistor 61 is connected to the second input end of the controller 55. The controller 55 is used to generate a second control signal based on the voltage input through the second input end, and output the second control signal to the gate of the MOS transistor 54 through the output end of the controller 55. The second control signal is used to control the on / off of the MOS transistor 54. One end of the filter circuit 62 is connected to the second input end of the controller 55, and the other end of the filter circuit 62 is grounded. It should be noted that the voltage information collected by the resistor 61 is transmitted to the controller 55, and the output voltage VDC is kept constant through the internal logic control of the controller 55.

[0085] Optionally, the filtering circuit 62 may include a third resistor 621 and a second capacitor 622 connected in parallel.

[0086] Optionally, the first capacitor 57 may be specifically a BULK capacitor.

[0087] When the above circuit is in operation, the current output by the AC power supply 52 is connected to the current input terminal of the magnetic device 51 after passing through the rectifier bridge 58, and then flows out from the current output terminal of the magnetic device 51. Since the windings in the magnetic device are staggered and wound on the same magnetic core, the current directions of adjacent windings are opposite, such as Figure 4 The example given.

[0088] The above circuit is a boost PFC circuit, and its basic working principle is as follows Figure 7 and Figure 8 As shown, there are two working states:

[0089] Working state 1, such as Figure 7 As shown, the MOS tube 54 is turned on, and the input voltage charges the magnetic device 51 to store energy. At this time, the energy storage voltage equation of the magnetic device 51 is:

[0090]

[0091] Among them, V Lb is the voltage across the magnetic device 51; V in is the input voltage of the circuit; Lb is the inductance of the magnetic device 51; i Lb is the inductor current of the magnetic device 51; Δi Lb_on is the rate of change of the inductor current during the on-time of the MOS tube 54; t on is the turn-on time of the MOS tube 54 in one cycle.

[0092] At this time, the energy of the load Ro is provided by the first capacitor 57 .

[0093] Working state 2, such as Figure 8 As shown, the MOS tube 54 is turned off, and the input voltage and the magnetic device 51 simultaneously supply power to the load Ro. At this time, the output voltage V o will be higher than the input voltage V in At this time, the discharge voltage equation of the magnetic device 51 is:

[0094]

[0095] Among them, V Lb is the voltage across the magnetic device 51; V o is the output voltage of the circuit; V in is the input voltage of the circuit; L b is the inductance of the magnetic device 51; i Lb is the inductor current of the magnetic device 51; Δi Lb_off is the rate of change of the inductor current during the off time of the MOS tube 54; t off is the off time of the MOS tube 54 in one cycle.

[0096] According to the volt-second balance, the charging inductor current change rate Δi Lb_on and the rate of change of the inductor current during discharge Δi Lb_off are equal, so we have:

[0097] (V o -V in )·t off =V in ·t on

[0098]

[0099] According to the above derivation, since (t off +t on )>t off , so the output voltage V o Greater than the input voltage V in , thus achieving boost.

[0100] Application 2

[0101] Figure 9A schematic diagram of a circuit structure provided by another embodiment of the present invention. Figure 9 The circuit provided in this embodiment includes: the magnetic device 91 as described above, an AC power supply 92, a diode 93, a MOS transistor 94, a controller 95 and a first capacitor 96.

[0102] The drain of the MOS transistor 94 is connected to the AC power supply 92 through the rectifier bridge 97; the source of the MOS transistor 94 is respectively connected to the current input end of the magnetic device 91 and the output end of the diode 93; the current output end of the magnetic device 91 is respectively connected to one end of the first capacitor 96 and the load, and the other end of the first capacitor 96 is grounded; the input end of the diode 93 is connected to the input end of the controller 95. The controller 95 is used to generate a control signal based on the voltage input through the input end, and output the control signal to the gate of the MOS transistor 94. The control signal is used to control the on / off of the MOS transistor 94.

[0103] Specifically, in this circuit, the functions of each component are as follows:

[0104] Magnetic device 91, used to store and release energy;

[0105] AC power supply 92, for providing AC power;

[0106] MOS transistor 94, used to control the storage and release of energy of the magnetic device 91;

[0107] Diode 93 is used for rectification to make the output a positive voltage;

[0108] The first capacitor 96 is used to maintain the output voltage VDC of the circuit constant, which is equivalent to gathering energy;

[0109] In an exemplary embodiment, Figure 10 As shown, in Figure 9 Based on the circuit structure shown, the circuit may further include a first resistor 98 and a filter circuit 99. One end of the first resistor 98 is connected to the current output terminal of the magnetic device 91, and the other end of the first resistor 98 is connected to the input terminal of the controller 95; one end of the filter circuit 99 is connected to the input terminal of the controller 95, and the other end of the filter circuit 99 is grounded.

[0110] Optionally, the filter circuit 99 may include a second resistor 991 and a second capacitor 992 connected in parallel.

[0111] Optionally, the first capacitor 96 may be a BULK capacitor.

[0112] When the above circuit is in operation, the current output by the AC power supply 92 is connected to the current input terminal of the magnetic device 91 after passing through the rectifier bridge 97 and the MOS transistor 94, and then flows out from the current output terminal of the magnetic device 91. Since the windings in the magnetic device 91 are wound alternately on the same magnetic core, the current directions of adjacent windings are opposite, such as Figure 4 The example given.

[0113] The above circuit is a step-down PFC circuit, and its basic working principle is as follows: Figure 11 and Figure 12 As shown, there are two working states:

[0114] Working state 1, such as Figure 11 As shown, the MOS tube 94 is turned on, and the input voltage charges the magnetic device 91 to store energy. At this time, the energy storage voltage equation of the magnetic device 91 is:

[0115]

[0116] Among them, V Lb is the voltage across the magnetic device 91; V in is the input voltage of the circuit; L b is the inductance of the magnetic device 91; i Lb is the inductor current of the magnetic device 91; Δi Lb_on is the rate of change of the inductor current during the on-time of the MOS tube 94; t on is the turn-on time of the MOS tube 94 in one cycle.

[0117] At this time, the energy of the load Ro is provided by the first capacitor 96 .

[0118] Working state 2, such as Figure 12 As shown, the MOS tube 94 is turned off, and the magnetic device 91 supplies power to the load Ro. At this time, the discharge voltage equation of the magnetic device 91 is:

[0119]

[0120] Among them, V Lb is the voltage across the magnetic device 91; V o is the output voltage of the circuit; V in is the input voltage of the circuit; L b is the inductance of the magnetic device 91; i Lb is the inductor current of the magnetic device 91; Δi Lb_off is the rate of change of magnetic inductance current during the off time of MOS tube 94; t off is the off time of the MOS tube 94 in one cycle.

[0121] According to the volt-second balance, the charging inductor current change rate ΔiLb_on and the rate of change of the inductor current during discharge Δi Lb_off are equal, so we have:

[0122] V o ·t off =(V in -V o )·t on

[0123]

[0124] According to the above derivation, since (t off +t on )>t off , so the output voltage V o Less than the input voltage V in , thus achieving a voltage reduction.

[0125] Typically, the MOS tubes in the above-mentioned circuits operate at an operating frequency of tens to hundreds of kHz. Similarly, the current in the magnetic device will also change in a form of such a high frequency. As a result, the magnetic field and electric field change rates of the windings in the magnetic device are very large, thereby generating a large eddy current effect and causing serious eddy current losses. If the method provided by the present invention is adopted, in which the windings are staggered and the currents of adjacent windings are reversed, the magnetic field and electric field between adjacent windings in each cycle can cancel each other out, thereby reducing the generation of eddy currents and achieving the purpose of reducing eddy current losses, greatly reducing the temperature rise of the magnetic device, and effectively extending its service life.

[0126] It should be noted that it should be understood that the division of the various modules of the above device is merely a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. Moreover, these modules can all be implemented in the form of software called by a processing element; or they can all be implemented in the form of hardware; or some modules can be implemented in the form of software called by a processing element, and some modules can be implemented in the form of hardware. For example, the processing module can be a separately established processing element, or it can be integrated into a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called by a processing element of the above device to perform the functions of the above processing module. The implementation of other modules is similar. In addition, these modules can all or partly be integrated together, or they can be implemented independently. The processing element here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by the hardware integrated logic circuit in the processor element or by instructions in the form of software.

[0127] Although only certain components and embodiments of the present invention have been illustrated and described, many modifications and variations (e.g., changes in the size, dimensions, structure, shape and proportions of the various components, mounting arrangements, use of materials, colors, orientations, etc.) may occur to those skilled in the art without actually departing from the scope and spirit of the claims. Moreover, in order to provide a concise description of the exemplary embodiments, not all components of an actual implementation may have been described. It should be understood that in the development of any such actual implementation, as in any engineering or design project, several specific implementation decisions may be made. Such development work may be complex and time-consuming, but will remain a routine procedure of design, processing, and manufacturing for those of ordinary skill who benefit from the present invention without undue experimentation.

[0128] It should be understood that the various numbers used in the embodiments of the present invention are merely for ease of description and are not intended to limit the scope of the embodiments of the present invention. In the embodiments of the present invention, the order of the sequence numbers of the above-mentioned processes does not necessarily indicate the order in which they are executed. The order in which the processes are executed is determined by their functions and inherent logic, and does not constitute any limitation on the implementation of the embodiments of the present invention.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic device, characterized in that: include: A current input terminal, a current output terminal, and at least two windings connected in parallel between the current input terminal and the current output terminal, wherein the at least two windings are wound alternately on a magnetic core, and the current flow direction of the winding is opposite to the current flow direction of the adjacent winding; The circuit including the magnetic device includes: an AC power supply, a diode, a MOS tube, a controller, a first resistor and a first capacitor, wherein: The current input terminal of the magnetic device is connected to the AC power supply through a rectifier bridge; The current output end of the magnetic device is connected to the input end of the diode and the drain of the MOS tube respectively; The output end of the diode is connected to one end of the first capacitor and the load respectively, and the other end of the first capacitor is grounded; The source of the MOS transistor is connected to the first input terminal of the controller and one end of the first resistor, respectively. The other end of the first resistor is grounded. The controller is used to generate a first control signal according to the voltage input through the first input terminal, and output the first control signal to the gate of the MOS transistor through the output terminal of the controller. The first control signal is used to control the on / off of the MOS transistor.

2. The magnetic device according to claim 1, characterized in that The magnetic core is a ring structure.

3. The magnetic device according to claim 1 or 2, characterized in that: The circuit further includes a second resistor and a filter circuit, wherein: One end of the second resistor is connected to the output end of the diode, and the other end of the second resistor is connected to the second input end of the controller. The controller is used to generate a second control signal according to the voltage input through the second input end, and output the second control signal to the gate of the MOS transistor through the output end of the controller. The second control signal is used to control the on / off of the MOS transistor. The filter circuit has one end connected to the second input end of the controller and the other end grounded.

4. The magnetic device according to claim 3, characterized in that The filtering circuit includes a third resistor and a second capacitor connected in parallel.

5. The magnetic device according to claim 4, characterized in that The first capacitor is a BULK capacitor.

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