A coupled inductor, coupling factor adjusting circuit and converter

Abstract

The utility model relates to the technical field of inductance, disclose a kind of coupling inductance, coupling coefficient adjusting circuit and converter, coupling inductance at least two separate inductance, separate inductance includes first magnetic core and the first winding and second winding of being wound in the both sides of first magnetic core, the first winding of any separate inductance is used to connect corresponding external input loop, the second winding of different separate inductance is in turn connected in series and forms closed loop circuit, the exciting inductance of different separate inductance is same, as long as the exciting inductance of separate inductance is kept consistent, current in series wire will generate same induced voltage in all separate inductance, i.

Description

Technical Field

[0001] This utility model relates to the field of inductor technology, and in particular to a coupled inductor, a coupling coefficient adjustment circuit and a converter. Background Technology

[0002] As the power rating of converters continues to increase, the voltage and current stress of a single converter can no longer meet the requirements. Interleaved parallel technology can effectively increase the switching frequency, reduce current ripple, and reduce inductor size. In multi-channel interleaved parallel converters, the inductance of each converter unit is smaller than that of a single-channel converter; however, the increased number of inductors still occupies a significant portion of the converter's volume and increases losses. Using coupled inductors can increase the equivalent inductance of each phase in the converter, thereby reducing ripple current on the inductors. Therefore, by using magnetic integration technology to integrate multiple inductors onto a single magnetic core, the number and size of magnetic components in the converter can be further reduced. Furthermore, the mutual coupling between multiple inductors further reduces ripple current on the inductors, ultimately improving the overall efficiency and power density of the converter.

[0003] In related technologies, coupled inductors are used in multiphase interleaved parallel converters to improve power density and overall efficiency. Currently, magnetic integration technology for coupled inductors is generally achieved through direct coupling via a shared magnetic circuit. This involves winding two or more discrete inductors onto a single magnetic core, and adding a common magnetic post with a shared magnetic circuit between adjacent winding posts for decoupling or adjusting the coupling coefficient of the coupled inductors. This scheme, using core coupling, improves the integration of the magnetic components and reduces the overall size; however, it suffers from magnetic circuit asymmetry issues for multiphase coupled inductors. Utility Model Content

[0004] In view of this, the present invention provides a coupled inductor, a coupling coefficient adjustment circuit and a converter to solve or partially solve the technical problem of insufficient magnetic circuit asymmetry in related technologies.

[0005] The technical solution proposed by this utility model is as follows: In a first aspect, this utility model proposes a coupled inductor, including at least two separate inductors. Each separate inductor includes a first magnetic core and a first winding and a second winding wound on both sides of the first magnetic core. The first winding of any separate inductor is used to connect to the corresponding external input circuit. The second windings of different separate inductors are connected in series to form a closed loop. The excitation inductance of different separate inductors is the same.

[0006] The coupled inductor of this invention uses a circuit to couple multiple separate inductors. Each independent separate inductor is connected in series by a wire. As long as the excitation inductance of the separate inductors is kept consistent, the current in the series wire will generate the same induced voltage in all the separate inductors. That is, the coupling coefficient of the separate inductors is kept consistent. This is easier to achieve than the complete equality of the magnetic circuit in magnetic coupling. Therefore, the coupled inductor of this invention has high magnetic circuit symmetry.

[0007] In some alternative embodiments, the coupling inductor further includes an auxiliary inductor; the auxiliary inductor includes a second magnetic core and a third winding wound on the second magnetic core, the third winding being connected in series between any two adjacent second windings.

[0008] In this method, the coupling coefficient of the coupled inductor is determined by the inductance of the auxiliary inductor. The coupling coefficient of the coupled inductor can be indirectly adjusted by selecting auxiliary inductors with different inductance values, so that the coupling relationship can be quickly adjusted without redesigning the core air gap. The coupling coefficient is easy to adjust.

[0009] In some alternative implementations, the auxiliary inductor is a surface-mount inductor.

[0010] In this method, the surface mount inductor is easy to replace on the circuit board. The coupling coefficient of the coupling inductor can be adjusted by replacing it with a surface mount inductor of the same package but different inductance values, which is convenient.

[0011] Secondly, this utility model proposes a coupling coefficient adjustment circuit for a coupled inductor, including a first control circuit and a coupled inductor as described in any of the first aspects of this utility model. The first control circuit and the third winding are connected in series and inserted between any two adjacent second windings. The first control circuit is used to control the on / off state of the connection between the third winding and the adjacent second winding.

[0012] The coupling coefficient adjustment circuit of this utility model controls the on / off state of the connection between the third winding and the adjacent second winding through a first control circuit. When the first control circuit is on, the coupling coefficient of the coupling inductor is determined by the inductance of the auxiliary inductor. When the first control circuit is off, the coupling coefficient of the coupling inductor is 0, thereby realizing the control of the coupling coefficient of the coupling inductor.

[0013] In some alternative embodiments, the coupling coefficient adjustment circuit of the coupled inductor further includes a second control circuit connected in parallel with a series branch including the first control circuit and the third winding. The second control circuit is used to control whether to short-circuit the series branch including the first control circuit and the third winding.

[0014] In this method, the coupling coefficient can be further adjusted by combining the first control circuit and the second control circuit. When the series branch including the first control circuit and the third winding is short-circuited by the second control circuit, the coupling coefficient of the coupled inductor is 1, which further widens the adjustment range of the coupling coefficient.

[0015] In some alternative embodiments, the first control circuit includes a first controllable switch, the second winding includes a first pin and a second pin, the third winding includes a third pin and a fourth pin, the first connection terminal of the first controllable switch is connected to the first pin of any one of the two adjacent second windings into which the third winding is inserted, the second connection terminal of the first controllable switch is connected to the third pin of the third winding, and the fourth pin of the third winding is connected to the second pin of the other of the two adjacent second windings into which the third winding is inserted.

[0016] In this method, the first controllable switch can conveniently control the on / off state between adjacent second windings, and can precisely adjust whether the third winding of the auxiliary inductor is connected, thereby achieving adjustment of the coupling coefficient.

[0017] In some alternative implementations, the first controllable switch is a relay.

[0018] In this method, a relay is used as the first controllable switch, which can ensure reliable on / off control when adjusting the coupling coefficient, thereby improving the safety of the circuit.

[0019] In some alternative implementations, the second control circuit includes a second controllable switch, the first connection terminal of the second controllable switch being connected to the first connection terminal of the first controllable switch, and the second connection terminal of the second controllable switch being connected to the fourth pin of the third winding.

[0020] In this method, the second controllable switch can work in conjunction with the first controllable switch and the third winding to select whether to connect the third winding of the auxiliary inductor and whether to disconnect the connection between adjacent discrete inductors according to the input control signal.

[0021] In some alternative implementations, the second controllable switch is a relay.

[0022] In this method, the use of a relay as the second controllable switch ensures reliable on / off control when adjusting the coupling coefficient, thereby improving circuit safety.

[0023] Thirdly, this utility model proposes a converter, including a coupling coefficient adjustment circuit for the coupled inductor as described in any of the second aspects of this utility model. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the first type of coupled inductor in the embodiments of this utility model; Figure 2 This is a schematic diagram of the structure of the second type of coupled inductor in this embodiment of the present invention; Figure 3 This is a circuit diagram of the first coupling coefficient adjustment circuit in this embodiment of the present invention; Figure 4 This is a circuit diagram of the second coupling coefficient adjustment circuit in this embodiment of the present invention; Figure 5 for Figure 4 Top view of the component arrangement of the coupling coefficient adjustment circuit for a medium-coupled inductor; Figure 6 This is a circuit diagram of the first control circuit and the second control circuit in an embodiment of the present utility model; Figure 7 This is an isometric view of the component arrangement of the coupling coefficient adjustment circuit for the coupled inductor in this embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1. Printed circuit board; 2. Second pin; 3. First pin; 4. Fourth pin; 5. Third pin; 6. First controllable switch; 7. Second controllable switch. Detailed Implementation

[0027] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0028] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. The term "equal" includes absolute equality and approximate equality, wherein the acceptable deviation range for approximate equality is, for example, the difference between two equal items being less than or equal to 5% of either one. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0030] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0031] In related technologies, the magnetic integration technology of coupled inductors is achieved through direct coupling via a shared magnetic circuit. This involves using a core-coupled inductor method, where the windings of two or more discrete inductors are wound onto a single magnetic core. A common magnetic post with a shared magnetic circuit is added between adjacent winding posts for decoupling or adjusting the coupling coefficient of the coupled inductors. This method has the following drawbacks: firstly, it introduces magnetic circuit asymmetry for multi-phase coupled inductors and increases structural complexity; secondly, adjusting the decoupling or coupling coefficient between coupled inductors requires readjusting the air gap of the magnetic core, which increases design time and cost.

[0032] In view of this, the present invention provides a coupled inductor, a coupling coefficient adjustment circuit and a converter, thereby solving the problem of magnetic circuit asymmetry in existing coupled inductors during multi-phase coupling, as well as the problem of difficulty in quickly adjusting the coupling coefficient and coupling relationship between coupled inductors.

[0033] like Figure 1 As shown, the coupling inductor of this utility model embodiment includes at least two separate inductors. Each separate inductor includes a first magnetic core and a first winding and a second winding wound on both sides of the first magnetic core. The first winding of any separate inductor is used to connect to the corresponding external input circuit. The second windings of different separate inductors are connected in series to form a closed loop. The excitation inductance of different separate inductors is the same.

[0034] Specifically, all separate inductors are main power inductors with consistent specifications and equal inductance, and each separate inductor has an independent magnetic core.

[0035] A split inductor comprises a first magnetic core, a first winding, and a second winding, with the first and second windings sharing a single magnetic core. In one example, the first magnetic core is an iron core, and the split inductor is constructed by winding the first and second windings on both sides of the iron core.

[0036] The number of separate inductors can be set according to the application scenario of the coupled inductors. For example, when the coupled inductors are used in a four-phase interleaved boost circuit, four separate inductors are set, each corresponding to one phase of the four-phase interleaved boost circuit. The first winding pin of the separate inductor is the power input / output pin, which can be led out to the outside through connectors or direct wiring as needed. The second winding of the separate inductor is connected in series to form an indirect coupling loop.

[0037] Compared to inductors coupled by a magnetic core, the structure of the coupled inductor of this invention has better symmetry. In traditional magnetically coupled inductors, when there are many windings, the coupling coefficient between two windings with equal magnetic circuits is relatively consistent. However, the coupling coefficient between two windings with longer and shorter magnetic circuits will be asymmetrical due to the asymmetry of the magnetic circuits. This is the limitation of current magnetically coupled inductors.

[0038] The coupling inductor of this invention uses circuit coupling, connecting the individual separate inductors in series with wires. As long as the excitation inductance of the separate inductors is the same, the current in the series wires will generate the same induced voltage in all the separate inductors. The specific derivation process is as follows: The discrete inductors are L1 to Ln, where n is an integer greater than or equal to 2. If a current I flows through the primary side of discrete inductor L1, an induced current will be generated in the series conductor. At this point, the following relationship will be satisfied:

[0039]

[0040]

[0041]

[0042] Solving the above equations simultaneously, we can obtain:

[0043] in, For the magnetizing inductance of all discrete inductors, The leakage inductance is in series, and N is the number of discrete inductors. The primary input voltage of the discrete inductor. The voltage induced on the remaining discrete inductors, The current in the magnetizing inductor, This refers to the mutual inductance between the energized inductor and the other isolated inductors. The result shows that only the magnetizing inductance of the isolated inductors is needed. To maintain consistency, the mutual inductance between all separate inductors Maintaining consistency means keeping the coupling coefficient consistent. Maintaining consistency in discrete inductors is easier to achieve than ensuring complete equality in the magnetic circuits of magnetic coupling; therefore, the coupled inductor of this invention exhibits high symmetry.

[0044] The coupled inductor of this invention uses a circuit to couple multiple separate inductors. Each independent separate inductor is connected in series by a wire. As long as the excitation inductance of the separate inductors is kept consistent, the current in the series wire will generate the same induced voltage in all the separate inductors. That is, the coupling coefficient of the separate inductors is kept consistent. This is easier to achieve than the complete equality of the magnetic circuit in magnetic coupling. Therefore, the coupled inductor of this invention has high magnetic circuit symmetry.

[0045] like Figure 2 As shown, in some optional embodiments, the coupling inductor further includes an auxiliary inductor Lk; the auxiliary inductor Lk includes a second magnetic core and a third winding wound on the second magnetic core, the third winding being connected in series between any two adjacent second windings.

[0046] Specifically, the auxiliary inductor Lk has only one winding and one magnetic core, namely the second magnetic core and the third winding. The inductance value of the auxiliary inductor Lk is relatively small, which is used to adjust the coupling coefficient of the coupling inductor.

[0047] The coupling coefficient k of the coupled inductor is determined by the selected inductance of the auxiliary inductor Lk. Therefore, the coupling coefficient of the coupled inductor can be indirectly adjusted by selecting auxiliary inductors Lk with different inductance values, and the coupling relationship can be quickly adjusted. When it is necessary to adjust the coupling coefficient, there is no need to redesign the core air gap, and the coupling coefficient adjustment is convenient.

[0048] Furthermore, the auxiliary inductor Lk is a surface-mount inductor.

[0049] Specifically, surface mount inductors with the same package can have different inductance values. Therefore, when the auxiliary inductor Lk is placed on the printed circuit board (PCB), the auxiliary inductor Lk can be directly replaced with an inductor with the same package but a different inductance value on the PCB, and the coupling coefficient of the coupling inductor can be adjusted in turn.

[0050] In this method, the surface mount inductor is easy to replace on the circuit board. The coupling coefficient of the coupling inductor can be adjusted by replacing it with a surface mount inductor of the same package but different inductance values, which is convenient.

[0051] like Figure 3 As shown, this utility model embodiment also proposes a coupling coefficient adjustment circuit for a coupled inductor, including a first control circuit and a coupled inductor as described in any of the above embodiments. The first control circuit and the third winding are connected in series and inserted between any two adjacent second windings. The first control circuit is used to control the on / off state of the connection between the third winding and the adjacent second winding.

[0052] Specifically, the first control circuit can be implemented using switching devices. The first control circuit mainly regulates the coupling relationship of the coupled inductor by controlling the connection and disconnection between each winding.

[0053] The coupling coefficient adjustment circuit of this utility model controls the on / off state of the connection between the third winding and the adjacent second winding through the first control circuit. When the first control circuit is on, the coupling coefficient of the coupling inductor is determined by the inductance of the auxiliary inductor Lk. When the first control circuit is off, the coupling coefficient of the coupling inductor is 0, thereby realizing the control of the coupling coefficient of the coupling inductor.

[0054] like Figure 4 As shown, in some optional embodiments, the coupling coefficient adjustment circuit of the coupled inductor further includes a second control circuit, which is connected in parallel with the series branch including the first control circuit and the third winding. The second control circuit is used to control whether to short-circuit the series branch including the first control circuit and the third winding.

[0055] Specifically, the first control circuit can be implemented using a switching device. When the first control circuit is turned on, the series branch of the first control circuit and the third winding is short-circuited, and the second windings of each separate inductor are connected in series to form a closed loop.

[0056] The coupling coefficient of the coupling inductor is further adjusted by the first control circuit and the second control circuit. The adjustment principle is as follows: when both the first control circuit and the second control circuit are disconnected, the indirect coupling loop is open, and the coupling coefficient of the coupling inductor is 0; when the first control circuit is on and the second control circuit is off, the coupling coefficient of the coupling inductor is k, where k is determined by the inductance of the selected auxiliary inductor Lk; when the first control circuit is off and the second control circuit is on, the indirect coupling loop is short-circuited, and the coupling coefficient of the coupling inductor is 1.

[0057] In this embodiment, the coupling coefficient is further adjusted by combining the first control circuit and the second control circuit, thereby further widening the adjustment range of the coupling coefficient.

[0058] like Figure 5As shown, in some optional embodiments, the first control circuit includes a first controllable switch 6, the second winding includes a first pin 3 and a second pin 2, the third winding includes a third pin 5 and a fourth pin 4, the first connection terminal of the first controllable switch 6 is connected to the first pin 3 of any one of the two adjacent second windings into which the third winding is inserted, the second connection terminal of the first controllable switch 6 is connected to the third pin 5 of the third winding, and the fourth pin 4 of the third winding is connected to the second pin 2 of the other one of the two adjacent second windings into which the third winding is inserted.

[0059] Specifically, for each winding, its two ends are the first pin 3 and the second pin 2 of the winding, respectively. For example... Figure 1 As shown, the separation inductor, auxiliary inductor Lk, and first control circuit are mounted on printed circuit board 1. The two pins in the second winding, which are clockwise along the indirect coupling loop, are respectively labeled as the first pin 3 of the second winding and the second pin 2 of the second winding. The two pins in the third winding, which are counterclockwise along the indirect coupling loop, are respectively labeled as the third pin 5 and the fourth pin 4.

[0060] The first controllable switch 6 includes two connection terminals and one controlled terminal. The controlled terminal is connected to a controller (not shown in the figure), and the controller inputs a control signal to control the first controllable switch 6 to turn on and off.

[0061] The first controllable switch 6 can be a relay, a switching transistor, or the like. By controlling the on and off states of the first controllable switch 6, the coupling coefficient of the coupling inductor can be adjusted.

[0062] The first controllable switch 6 can be used to conveniently control the on / off state between adjacent second windings, and can precisely adjust whether the third winding of the auxiliary inductor Lk is connected, thereby achieving adjustment of the coupling coefficient.

[0063] like Figure 6 As shown, in some optional embodiments, the first controllable switch 6 is a relay. Using a relay as the first controllable switch 6 ensures reliable on / off control when adjusting the coupling coefficient, thus improving circuit safety.

[0064] In some alternative embodiments, the second control circuit includes a second controllable switch 7, the first connection terminal of the second controllable switch 7 is connected to the first connection terminal of the first controllable switch 6, and the second connection terminal of the second controllable switch 7 is connected to the fourth pin 4 of the third winding.

[0065] Specifically, the second controllable switch 7 includes two connection terminals and one controlled terminal. The controlled terminal is connected to a controller (not shown in the figure), and the controller inputs a control signal to control the second controllable switch 7 to turn on and off.

[0066] It should be understood that the first controllable switch 6, the second controllable switch 7, the discrete inductor, and the auxiliary inductor Lk can be installed on different printed circuit boards 1 as needed via plug-ins, or as follows: Figure 7 As shown, the various components are directly integrated into the printed circuit board 1 of the application.

[0067] The second controllable switch 7 can be a relay, a switching transistor, etc. The coupling coefficient of the coupling inductor can be adjusted by controlling the on and off states of the first controllable switch 6 and the second controllable switch 7. Specifically, when both the first and second control circuits are off, the indirect coupling loop is open, and the coupling coefficient of the coupling inductor is 0; when the first control circuit is on and the second control circuit is off, the coupling coefficient of the coupling inductor is k, where k is determined by the inductance of the selected auxiliary inductor Lk; when the first control circuit is off and the second control circuit is on, the indirect coupling loop is short-circuited, and the coupling coefficient of the coupling inductor is 1.

[0068] In this embodiment, the second controllable switch 7 can work in conjunction with the first controllable switch 6 and the third winding to select whether to connect the third winding of the auxiliary inductor Lk and whether to disconnect the connection between adjacent separate inductors according to the input control signal, thereby adjusting the coupling coefficient of the coupled inductor to any one of 1, k or 0, and widening the range of coupling coefficient adjustment.

[0069] In some alternative embodiments, the second controllable switch 7 is a relay. Using a relay as the second controllable switch 7 ensures reliable on / off control when adjusting the coupling coefficient, thus improving circuit safety.

[0070] This invention also proposes a converter, including a coupling coefficient adjustment circuit for the coupled inductor as described in any of the above embodiments of this invention.

[0071] The number of separate inductors in the coupling inductor corresponds to the number of phases in the voltage conversion circuit of the converter. For example, when the converter adopts a four-phase interleaved boost circuit, four separate inductors are set, and the first winding of the separate inductor is connected to the input of the corresponding phase.

[0072] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions and modifications to these embodiments without departing from the spirit and scope of protection of this utility model, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A coupled inductor, characterized in that, include: At least two separate inductors, each inductor comprising a first magnetic core and a first winding and a second winding wound on both sides of the first magnetic core. The first winding of any of the separate inductors is used to connect to a corresponding external input circuit. The second windings of different separate inductors are connected in series to form a closed loop. The excitation inductance of different separate inductors is the same.

2. The coupled inductor according to claim 1, characterized in that, It also includes auxiliary inductors; The auxiliary inductor includes a second magnetic core and a third winding wound on the second magnetic core, wherein the third winding is connected in series between any two adjacent second windings.

3. The coupled inductor according to claim 2, characterized in that, The auxiliary inductor is a surface mount inductor.

4. A coupling coefficient adjustment circuit for a coupled inductor, characterized in that, Includes a first control circuit and a coupled inductor as described in any one of claims 1 to 3; The first control circuit and the third winding are connected in series and inserted between any two adjacent second windings. The first control circuit is used to control the on / off state of the connection between the third winding and the adjacent second winding.

5. The coupling coefficient adjustment circuit for the coupled inductor according to claim 4, characterized in that, It also includes a second control circuit, which is connected in parallel with the series branch including the first control circuit and the third winding. The second control circuit is used to control whether to short-circuit the series branch including the first control circuit and the third winding.

6. The coupling coefficient adjustment circuit for the coupled inductor according to claim 5, characterized in that, The first control circuit includes a first controllable switch, the second winding includes a first pin and a second pin, the third winding includes a third pin and a fourth pin, the first connection terminal of the first controllable switch is connected to the first pin of any one of the two adjacent second windings into which the third winding is inserted, the second connection terminal of the first controllable switch is connected to the third pin of the third winding, and the fourth pin of the third winding is connected to the second pin of the other one of the two adjacent second windings into which the third winding is inserted.

7. The coupling coefficient adjustment circuit for the coupled inductor according to claim 6, characterized in that, The first controllable switch is a relay.

8. The coupling coefficient adjustment circuit for the coupled inductor according to claim 6, characterized in that, The second control circuit includes a second controllable switch, the first connection terminal of the second controllable switch is connected to the first connection terminal of the first controllable switch, and the second connection terminal of the second controllable switch is connected to the fourth pin of the third winding.

9. The coupling coefficient adjustment circuit for the coupled inductor according to claim 8, characterized in that, The second controllable switch is a relay.

10. A converter, characterized in that, Includes a coupling coefficient adjustment circuit for the coupled inductor as described in any one of claims 4 to 9.

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