Flux-multiplying inductor, flux-multiplying transformer, and applications thereof

Abstract

Disclosed are a flux-multiplying inductor, a flux-multiplying transformer, and applications thereof. The flux-multiplying inductor comprises one or a plurality of magnetic cores and a plurality of coils surrounding the one or the plurality of magnetic cores and connected in parallel and / or in series. The flux-multiplying transformer comprises: primary coils implemented as a flux-multiplying inductor; and a secondary coil surrounding at least one magnetic core(s) of the flux-multiplying inductor.

Description

Flux-increasing inductors and flux-increasing transformers and their applications

[0001] Embodiments of the present invention relate to a flux multiplying inductor (hereinafter referred to as “FMI”), a flux multiplying transformer (hereinafter referred to as “FMT”), and applications thereof.

[0002] An inductor is an electrical component that stores energy in a magnetic field when current flows through it. When the current flowing through a coil changes, the time-varying magnetic field induces an electromotive force (EMF) in the conductor according to Faraday's law of induction.

[0003] A transformer is a device that transfers electrical energy from a primary coil to a secondary coil. When current flows through the primary coil connected to a power source, a magnetic field is formed in the magnetic core. Changes in the magnetic field transmitted through the magnetic core generate an electromotive force in the secondary coil, thereby causing current to be generated in the secondary coil.

[0004] The technical problem that the embodiments of the present invention aim to solve is to provide a flux-increasing inductor and a flux-increasing transformer capable of increasing circuit efficiency.

[0005] An example of a flux-increasing inductor according to an embodiment of the present invention for achieving the above technical problem comprises: one or more cores; and a plurality of coils connected in parallel and / or series, surrounding the one or more cores.

[0006] In one embodiment, the core may be in the form of a closed loop or an open loop.

[0007] In another embodiment, there is a single core, and the plurality of coils may be in a form that wraps around the single core.

[0008] In another embodiment, there are multiple magnetic cores, and the multiple coils may be in a form that wraps around the multiple magnetic cores.

[0009] In another embodiment, the direction of the flux generated by the plurality of coils may be the same.

[0010] In another embodiment, the voltage waves applied to at least two of the plurality of coils may be different from each other, but the direction of the flux coming from the plurality of coils may be the same.

[0011] As another embodiment, a flux-increasing inductor of a recursive configuration can be implemented by connecting the flux-increasing inductors in series and / or parallel.

[0012] An example of a flux-increasing transformer according to an embodiment of the present invention for achieving the above technical problem comprises: primary coils implemented by the plurality of coils of the flux-increasing inductor; and a secondary coil surrounding the at least one core(s) of the flux-increasing inductor.

[0013] In one embodiment, the primary coils may include multiple coils connected in parallel and / or series, wrapping around multiple magnetic cores.

[0014] In another embodiment, the secondary coil may include a plurality of coils connected in series that surround the plurality of magnetic cores.

[0015] As another embodiment, a flux-increasing transformer with a recursive configuration can be implemented by cascading the output of the flux-increasing transformer to the input of another flux-increasing transformer.

[0016] As another embodiment, a switch-mode power supply including the flux-increasing transformer can be implemented.

[0017] According to an embodiment of the present invention, the amount of magnetic flux generated by the FMI is greater than or equal to the amount generated by an equivalent single inductor. In the FMT, more flux generated in the primary coil is collected by the secondary coil. In a circuit with a transformer, replacing the transformer with an FMT can increase the efficiency of the circuit.

[0018] Figure 1 shows the inductance Input voltage to a single inductor having eddy current A drawing illustrating an example of a circuit through which water flows,

[0019] Figure 2 shows mutual inductance A drawing illustrating an example of two inductors connected in parallel,

[0020] FIG. 3 is a drawing illustrating an example of a case composed of a single inductor.

[0021] FIG. 4 is a diagram illustrating an example of a general case of inductors connected in parallel.

[0022] Figure 5 shows the mutual inductance of two inductors A drawing illustrating an example of work connected in series,

[0023] FIG. 6 is a drawing illustrating an example of a parallel FMI using a single rod core.

[0024] FIG. 7 is a drawing illustrating an example of a parallel FMI using a single toroidal core.

[0025] FIG. 8 is a drawing illustrating an example of a serial type FMI using a single toroidal core.

[0026] FIG. 9 is a drawing illustrating an example of a parallel FMI using multiple magnetic cores.

[0027] FIG. 10 is a drawing illustrating an example of a serial type FMI using multiple magnetic cores.

[0028] FIG. 11 is a drawing illustrating an example of a parallel FMI using two toroidal cores.

[0029] FIG. 12 is a drawing illustrating an example of a serial FMI using two toroidal cores.

[0030] FIG. 13 is a drawing illustrating an example of a hybrid FMI.

[0031] FIG. 14 is a drawing illustrating an example of an FMI having two or more ports,

[0032] FIG. 15 is a drawing illustrating an example of a symbol of FMT,

[0033] FIG. 16 is a drawing illustrating an example of an FMT symbol with dot notation.

[0034] FIG. 17 is a drawing illustrating an example of two FMTs connected in series (cascade).

[0035] FIG. 18 is a diagram illustrating an example of an FMT used instead of a coupled inductor in a flyback converter circuit.

[0036] FIG. 19 is a drawing illustrating an example of the winding directions of coils of continuously connected FMTs to replace the combined inductor in the flyback converter circuit of FIG. 18.

[0037] FIG. 20 is a drawing illustrating an example of a winding configuration of a secondary coil that collects flux from all magnetic cores.

[0038] FIG. 21 is a drawing illustrating an example of a secondary coil of an FMT having two toroidal cores.

[0039] FIG. 22 is a drawing illustrating an example of an FMT in which primary coils are connected in parallel to two cores and secondary coils are wound on two cores.

[0040] FIG. 23 is a drawing illustrating an example of a secondary coil of an FMT having two toroidal cores.

[0041] FIG. 24 is a drawing illustrating an example of an FMT in which primary coils are connected in parallel to two magnetic cores and two secondary coils are connected in series.

[0042] FIG. 25 is a diagram illustrating an example of primary coils of an FMT in which two FMIs are connected in parallel, each having an FMI with two inductors connected in parallel to each core.

[0043] FIG. 26 is a diagram illustrating an example of an FMT formed by two cores, in which two parallel FMIs, each consisting of two inductors on a core, are connected in parallel on the primary side.

[0044] FIG. 27 is a diagram illustrating an example in which two parallel FMIs, each consisting of two inductors on a core, are connected in parallel on the primary side to form an FMT consisting of two cores.

[0045] FIG. 28 is a diagram illustrating an example of an FMT formed by two cores, in which two parallel FMIs, each consisting of two inductors on a core, are connected in series on the primary side.

[0046] FIG. 29 is a drawing illustrating an example of a parallel flyback converter using FMTs as part of two parallel units.

[0047] FIG. 30 is a diagram illustrating an example of an FMT made by connecting two FMTs of FIG. 27 in parallel at the input side and in series at the output side.

[0048] FIG. 31 is a drawing illustrating an example of a flyback converter using an FMT.

[0049] FIG. 32 is a diagram illustrating an example of the current flowing through one primary coil while the switch is turned on in the continuous conduction mode of the circuit of FIG. 31.

[0050] FIG. 33 is a diagram showing an example of the connections of the secondary sides of two transformers on the LM3481-FlybackEVM board, and

[0051] Figure 34 is a diagram showing an example of efficiency improvement according to various output currents and various input voltages.

[0052] Hereinafter, a flux-increasing inductor, a flux-increasing transformer, and their applications according to an embodiment of the present invention will be examined in detail with reference to the attached drawings.

[0053] 1. Flux Multiplying Inductor (FMI)

[0054] Figure 1 shows the inductance Input voltage to a single inductor having eddy current This is a diagram illustrating an example of a circuit through which water flows.

[0055] Inductance as shown in Fig. 1 A single inductor with input voltage eddy current When , the following equation holds. Here is a pulse or an alternating voltage.

[0056]

[0057] Figure 2 shows mutual inductance This is a diagram illustrating an example of two inductors connected in parallel. is the input voltage, is the total current. class are inductances and class These are the corresponding currents. class is the number of turns of the coils.

[0058] As shown in FIG. 2, two inductors are connected in parallel, and the input voltage as in FIG. 1 Let's consider a circuit to which is applied. To simplify the problem, we assume that the inductors have the inductance as shown in Fig. 1 Number of turns with the same value It is assumed that it has.

[0059]

[0060] currents class is the same value Let's assume it has.

[0061]

[0062] Then, voltage has the following relationship with respect to the change in current. Here is mutual inductance.

[0063]

[0064] Then, mutual inductance can be expressed as follows using the coupling coefficient k.

[0065]

[0066] Here, the range of k is as follows.

[0067]

[0068] voltage It is represented as follows.

[0069]

[0070] Figure 3 illustrates an example of a case consisting of a single inductor. Two inductors connected in parallel as in Figure 2 are represented as an equivalent single inductor. is a closed number.

[0071] The above equation is the inductance as shown in Fig. 3 The input voltage to a single inductor and the current It can be interpreted as a circuit that flows as much.

[0072] The circuit in Fig. 3 is composed of a single inductor as in Fig. 1, and also has the same voltage as in Fig. 1. Since is input, the following relationship holds.

[0073]

[0074] thus,

[0075]

[0076] If k = 0 here,

[0077]

[0078] In other words, if there is no mutual inductance between the two coils in Fig. 2, the equivalent inductance is the original inductance value It becomes half of.

[0079] If k = 1,

[0080]

[0081] In other words, if the two coils in Fig. 2 are perfectly coupled, their equivalent inductance and current values ​​are the same as those in Fig. 1.

[0082] Current in each inductor in Fig. 2 is as follows:

[0083]

[0084] A single inductor configuration as in Fig. 3 is treated as equivalent to the configuration of two inductors connected in parallel in Fig. 2.

[0085] Now our question is this: reluctance When this is the same, will these two configurations—namely, the configuration consisting of a single inductor as in FIG. 3 and the configuration with two inductors connected in parallel as in FIG. 2—have the same magnetic flux value?

[0086] It is assumed that the voltage is applied after the demagnetization of the core is completely completed. The total flux generated by the parallel coils in Fig. 2 It is as follows.

[0087]

[0088] inductance It is related to magnetic resistance as follows.

[0089]

[0090] magnetic resistance Since the core is constant once determined, the ratio to the square of the number of turns of the inductance must be a constant value. This applies even when composed of a single inductance as in Fig. 3, which consists of a single inductor as in Fig. 1. If the same core is used in the circuits of Fig. 1 and Fig. 3, it is as follows.

[0091]

[0092] In other words, the circuit of Fig. 3 uses the same magnetic core as in Fig. 1, and the inductance value in the circuit of Fig. 3 To make it so, the coil You have to wrap the bun.

[0093] Here only in this case and, otherwise, as follows.

[0094]

[0095] Flux generated from a single inductor in Fig. 3 It is as follows.

[0096]

[0097] The rain above is It becomes 1 only in this case. Otherwise, it is greater than 1.

[0098] Therefore, inductors connected in parallel generate more or equal flux than a single equivalent inductor when the same amount of current flows. Someone might ask why one would go out of their way to connect inductors in parallel to generate flux. He might say that since inductors connected in parallel can be represented as a single equivalent inductor, it is sufficient to generate flux with a single inductor.

[0099] However, as we have seen, when inductors are connected in parallel, they always generate more flux than a single inductor with its equivalent, except in the ideal case where k is 1.

[0100] Figure 4 is a diagram illustrating an example of a general case of inductors connected in parallel.

[0101] Generally, connected in parallel as in Fig. 4 For the k inductors, to simplify the problem, all have the same inductance value All have the same current value When it is said to have, it is as follows.

[0102]

[0103] And the following formula holds true.

[0104]

[0105] Here, is the first and It is the coupling coefficient between the nth coils and k a is the average of the joint coefficients.

[0106] The flux generated by the inductors connected in parallel in Fig. 4 and the flux generated by one equivalent inductor The ratio of is as follows.

[0107]

[0108] Therefore, by connecting inductors in parallel, it is possible to generate more flux with the same amount of current than an equivalent single inductor generates. It should be noted that the above ratio has the largest value when there is no mutual coupling between the inductors.

[0109] In general, a circuit of inductors with different inductance values ​​connected in parallel generates more than or equal to the flux generated by a single equivalent inductor circuit with the same amount of current, provided that the currents are in the same direction and the coils are in the same direction—that is, the fluxes generated by the coils are in the same direction. This is demonstrated below.

[0110] Inductances in Fig. 2 class They can be different from each other, and the wound numbers class Let's consider the case where they can be different from each other. Then, It is as follows.

[0111]

[0112] In that case, the total inductance It is as follows.

[0113]

[0114] Here It has the following relationship.

[0115]

[0116] Without loss of generality, let us assume the following.

[0117]

[0118] Here Let's define it as follows.

[0119]

[0120] Here, It is as follows.

[0121]

[0122] then,

[0123]

[0124] Since two inductors connected in parallel and their equivalent inductor have the same core, the following applies.

[0125]

[0126] Here is the number of turns of an equivalent inductor.

[0127] Since we stated that voltage is applied after the demagnetization of the core is completely completed, it is as follows.

[0128]

[0129] thus,

[0130]

[0131] currents class Since it was stated that they are in the same direction,

[0132]

[0133] The flux generated by an equivalent inductor is as follows.

[0134]

[0135] The flux generated by two inductors connected in parallel is:

[0136]

[0137] The ratio of the flux generated by two parallel-connected inductors to the flux generated by a single inductor is as follows:

[0138]

[0139] We need to show that the above formula is greater than or equal to 1.

[0140]

[0141] Therefore, the amount of flux generated by two inductors connected in parallel is greater than or equal to the amount of flux generated by a single equivalent inductor.

[0142] In cases where more than two inductors are connected in parallel, it is proven by mathematical induction as follows.

[0143] We have already proven the case where two inductors are connected in parallel. Now Let us assume that when inductors are connected in parallel, they generate a flux that is greater than or equal to the flux generated by a single equivalent inductor. Then, When k inductors are connected in parallel, the preceding If we represent the inductors as a single equivalent inductor, it transforms into a circuit with two inductors connected in parallel. However, Since it was stated that when inductors are connected in parallel, they generate a flux greater than or equal to that generated by a single equivalent inductor, the two parallel inductors formed in this way are It generates a flux less than or equal to that of the case where multiple inductors are connected in parallel. However, the two parallel inductors formed in this way generate a flux greater than or equal to that of the case represented by a single equivalent inductor. Therefore, overall When multiple inductors are connected in parallel, the resulting flux is greater than or equal to the flux generated by a single equivalent inductor. Therefore, generally, even when more than two inductors are connected in parallel, they generate an amount of flux greater than or equal to the flux generated by a single inductor equivalent to it.

[0144] So far, we have looked at the case where inductors are connected in parallel. Now let's look at the case where inductors are connected in series.

[0145] Figure 5 shows the mutual inductance of two inductors This is a drawing illustrating an example of a series connection. is the input voltage, is an electric current. class are inductances and class is the number of turns of the coils.

[0146] As shown in Fig. 5, two inductors are connected in series to generate flux in the same direction, and the input voltage Let's consider a circuit to which is applied. Then, in that case, the total inductance is as follows:

[0147]

[0148] Here It has the following relationship.

[0149]

[0150] Here, k is the coupling coefficient.

[0151] Without loss of generality, let us assume the following.

[0152]

[0153] Here Let's define it as follows.

[0154]

[0155] Here, It is as follows.

[0156]

[0157] then,

[0158]

[0159] Since each of the two inductors connected in series and their equivalent inductor have the same core, the following applies.

[0160]

[0161] Here is the number of turns of an equivalent inductor.

[0162] The flux generated by an equivalent inductor is as follows.

[0163]

[0164] The flux generated by two inductors connected in series is as follows.

[0165]

[0166] The ratio of the flux generated by two inductors connected in series to the flux generated by a single inductor is as follows:

[0167]

[0168] We need to show that the above formula is greater than or equal to 1.

[0169]

[0170] Therefore, the amount of flux generated by two inductors connected in series is greater than or equal to the amount of flux generated by a single equivalent inductor. This is proven in the case where more than two inductors are connected in series, just as in the parallel case above.

[0171] also When α is 1, that is, when the two inductors have the same inductance value, the ratio of the fluxes is as follows.

[0172]

[0173] The above ratio has a maximum value when the coupling coefficient k is 0. Therefore, just as with the parallel case, inductors connected in series generate the most flux when the coupling coefficient is 0.

[0174] In the case of inductors connected in parallel or series, the flux generated is equal to or greater than that of an equivalent single inductor; therefore, even when inductors are connected in a combination of parallel and series, the flux generated is equal to or greater than that of an equivalent single inductor.

[0175] Whether connected in parallel or in series, in order to generate more flux, the coupling coefficient must be as close to 0 as possible rather than close to 1. Until now, inductors with coils connected in parallel and / or in series such that the coupling coefficient is not close to 1 to utilize such flux increase have not existed.

[0176] We name inductors connected in parallel and / or in series such that the coupling factor is not 1 to generate more flux as “Flux Multiplying Inductors (FMI).” Even though there may be one or more inductors connected in parallel and / or in series to a single FMI, we will call the FMI a “one” inductor because it operates as a single inductor that generates more flux than a single equivalent inductor.

[0177] The coils of the FMI are wound to increase the flux. For example, in Fig. 4, the currents Energy flows in the same direction. Therefore, all coils must be wound in the same direction.

[0178] The coils of FMI should not be wound with excessive overlap, because doing so results in a high k value, which reduces the generated flux. The coils of FMI can be wound on a common core or on different cores. Generally, when there are multiple coils, some coils can be wound on different cores. The core(s) of the FMI must be such that the flux generated by the coils does not saturate when added together. For example, ferrite core(s) may be used, or air core(s) may be used. Additionally, core(s) with an air gap may be used.

[0179] An FMI in which inductors are connected in parallel is named a parallel type FMI (hereinafter referred to as “pFMI”), and an FMI in which inductors are connected in series is named a serial type FMI (hereinafter referred to as “sFMI”).

[0180] Figure 6 is a diagram illustrating an example of a pFMI using a single rod core.

[0181] Figure 7 illustrates an example of a pFMI using a single toroidal core. Here, the FMI has three coils on a single common core.

[0182] Figure 8 is a diagram illustrating an example of an sFMI using a single toroidal core.

[0183] Figure 9 is a diagram illustrating an example of a pFMI using multiple magnetic cores.

[0184] Figure 10 is a diagram illustrating an example of sFMI using multiple magnetic cores.

[0185] Figure 11 is a diagram illustrating an example of pFMI using two toroidal cores.

[0186] Figure 12 is a diagram illustrating an example of sFMI using two toroidal cores.

[0187] An example of a pFMI having five coils connected in parallel to a single common core is shown in Fig. 6. An example of a pFMI having a toroidal core is shown in Fig. 7. An example of an sFMI having a toroidal core is shown in Fig. 8. An example of a pFMI having multiple bar cores is shown in Fig. 9. An example of an sFMI connected in series to multiple cores is shown in Fig. 10.

[0188] Another example of a pFMI using two toroidal cores is shown in Fig. 11. Another example of an sFMI using two toroidal cores is shown in Fig. 12. FMIs with other configurations using cores of shapes other than rods or toroids are also possible.

[0189] A hybrid type FMI (hereinafter referred to as “hFMI”) can be created by connecting inductors in a mixed manner, combining parallel and series connections.

[0190] Figure 13 is a diagram illustrating an example of a hybrid FMI.

[0191] FIG. 13 illustrates an example of hFMI in which coils connected to each toroidal core form a single pFMI, and two pFMIs are connected in series. In FIG. 13, there is a pFMI in each toroidal core, but there may be a pFMI in one core and an sFMI in another core. Or there may be two sFMIs in two cores. Also, in FIG. 13, the FMIs in the two cores are connected in series, but they may also be connected in parallel. In FIG. 13, the series connection is between cores and the parallel connection is made within a core, but the parallel connection(s) and series connection(s) of coils may be made together within a single core to increase the flux. Since the flux increases when coils are connected in parallel and / or series, different FMI types or coils may be mixed and connected in series and / or parallel within a single core and / or between cores.

[0192] FIG. 14 is a drawing illustrating an example of an FMI having two or more ports.

[0193] FMI is more generalized and can have two or more ports and can have various different voltage waves as shown in Fig. 14. In Fig. 14, the voltage It is input to two inductors connected in parallel, and the voltage It is input into a single inductor. It is an FMI with two ports. In Fig. 14, there are coils connected in parallel to one port, but instead, there may be coils connected in series to that one port.

[0194] Since we assume that voltage waves are applied when the demagnetization of the core(s) is complete, the direction of the fluxes generated from the coils must be the same at any given moment.

[0195] To achieve this, the input voltage waveforms must be connected to the same power source. If the voltage(s) of one port must have a different value from the voltage(s) of another port, a voltage regulating module must be inserted between the power source and the port. Even in such a case, the ports remain connected to the same power source. Therefore, in a broad sense, an FMI with two or more ports can be viewed as a configuration where all ports are connected in parallel from the same power source.

[0196] FMIs can be connected to each other in series and / or parallel as needed to form a new FMI. The newly formed FMI can then become a component for forming another FMI, thereby recursively forming yet another FMI. In this way, various types of FMIs can be created.

[0197] FMI can be used as the primary side of a flux multiplying transformer (FMT) to be described in the next section.

[0198]

[0199] 2. Flux Multiplying Transformer (FMT)

[0200] Now, the flux generated by inductors connected in parallel and / or series can be collected by the secondary coil in the transformer configuration.

[0201] In the configuration of a transformer, the secondary coil collects flux generated from multiple primary coils. We name this type of transformer a “Flux Multiplying Transformer (FMT).”

[0202] Examples of primary coils of an FMT are shown in FIGS. 7 and 8. In these examples, a toroidal core was used. A secondary coil is wound over the core to collect the flux generated from the primary coils. Other examples of primary coils of an FMT are shown in FIGS. 9 and 10. A bar core was used in these examples. A secondary coil is wound over the core(s) to collect the generated flux. FMTs can be constructed using cores of shapes other than bar or toroidal cores. In fact, FMTs can be constructed using any closed-loop or open-loop core.

[0203] Generally, if primary coils are wound around a core, the secondary coil must be wound to wrap around the core in order to collect the flux generated from the primary coils of that core.

[0204] Figure 15 is a diagram illustrating an example of the symbol of FMT.

[0205] Figure 16 is a drawing illustrating an example of an FMT symbol with dot notation.

[0206] An FMT having two input terminals and two output terminals can be represented as in FIG. 15. Although not explicitly shown in FIG. 15, the primary coil in the figure consists of more than one coil connected in parallel and / or series. As in FIG. 16, dot notation may be applied to the symbol. The dot notation indicates the relative winding direction of the primary coil and the secondary coil.

[0207] FIG. 17 is a diagram illustrating an example of two FMTs connected in series (cascade).

[0208] Two or more FMTs can be cascaded to each other as shown in Fig. 17. Connecting FMTs in another way is explained next.

[0209] Now let's look at how FMT is usefully applied. The energy contained in an inductor Since it is proportional to the square of the magnetic field, it is therefore proportional to the square of the flux inside a given magnetic core. (Reference 1: Nannapaneni N. Rao, Fundamentals of Electromagnetics for Electrical and Computer Engineering, First Edition, Pearson Education, Upper Saddle River, New Jersey, p. 201.) Therefore, by increasing the flux, the energy in the inductor increases. This increased energy is discharged by the secondary coil of the FMT, thereby increasing the efficiency of the circuit.

[0210] Figure 18 is a diagram illustrating an example of an FMT used instead of a coupled inductor in a flyback converter circuit.

[0211] As an example of how an FMT can be used, let us look at a circuit using an FMT. Figure 18 shows a combined inductor, typically used in a flyback converter circuit, replaced with an FMT. In a flyback converter circuit, input energy is stored in the core while the switch is turned on. By using an FMT, the flux generated in the core through inductors connected in parallel or series by the input current is increased. In this case, the FMT operates as a combined inductor. In the present invention, the FMT is referred to as a transformer even though it operates as a combined inductor.

[0212] The number of turns of the FMT's secondary coil Let's assume that there are two inductors with the same inductance value connected in parallel or series on the primary side of the FMT. Flux Voltage in the secondary coil of an FMT having It is as follows.

[0213]

[0214] Meanwhile, let us consider a general transformer having a single primary coil with an inductance equivalent to that of the primary coils of the FMT above. Also, it has the number of turns of the secondary coil of the FMT above. Let's assume it has a secondary coil with the same number of turns as . Then the flux of the FMT is the flux generated from a single equivalent inductor in the primary coil of a typical transformer It has the following relationship with

[0215]

[0216] Then, the voltage in the secondary coil of a general transformer It is as follows.

[0217]

[0218] In other words, when the number of turns in the secondary coils is the same, the output voltage of the FMT increases compared to the output voltage of a general transformer, so the efficiency of the circuit can be improved by using the FMT. The conditions under which the efficiency of a circuit using an FMT can be improved will be explained next.

[0219] FIG. 19 is a diagram illustrating an example of the winding directions of the coils of cascade FMTs to replace the combined inductor in the flyback converter circuit of FIG. 18.

[0220] When FMTs connected in series are used in a circuit, the winding direction of the wires must be aligned with the requirements of the circuit. For example, when two FMTs are connected in series and used instead of a combined inductor in a flyback converter circuit as in FIG. 18, possible winding directions of the wires are shown in FIG. 19.

[0221] When more than one number of magnetic cores are used, in order to collect the flux generated through the primary coils, the secondary coil needs to surround the magnetic cores around which the primary coils are wound.

[0222] The process of collecting flux and converting it into current can be carried out in two ways. Here, we will explain the case where there are only two magnetic cores.

[0223] The first method involves collecting flux from two cores and converting it into current. The second method involves capturing flux from each core, converting it into current through a secondary coil wound around each core, and then summing the currents from those secondary coils. When there are many cores, these two methods can be combined. Of course, if necessary, instead of collecting flux from all cores, only some cores may be wrapped with secondary coil(s) to collect flux from only a subset of cores.

[0224] FIG. 20 is a diagram illustrating an example of a winding configuration of a secondary coil that collects flux from all magnetic cores.

[0225] An example of the first method is shown in FIG. 20, which can be used in the case of having a primary pFMI using three bar cores as in FIG. 9. Since the primary coils have already been shown in FIG. 9, FIG. 20 shows only the secondary coil that collects flux from all the cores.

[0226] FIG. 21 is a diagram illustrating an example of an FMT with two toroidal cores. Only the secondary coil is shown.

[0227] FIG. 22 is a diagram illustrating an example of an FMT in which primary coils are connected in parallel to two cores and secondary coils are wound around two cores.

[0228] FMI can be used as the primary of FMT. Figures 11 and 12 show an FMI using two toroidal cores, which can serve as part of an FMT. Figure 21 shows the secondary coil of an FMT wound over the cores of Figure 11 or Figure 12. This is another example of the first method. It demonstrates collecting flux from the primary coils by winding the secondary coil over the two toroidal cores. Figure 22 shows the symbol for such a configuration.

[0229] FIG. 23 is a diagram illustrating an example of an FMT with two toroidal cores. Only the secondary coils are shown. The flux from each primary coil generates a current corresponding to each secondary coil.

[0230] FIG. 23 shows that a secondary coil is wound around each core of the FMIs in FIG. 11 or FIG. 12 and the coils are connected in series to form an FMT. The secondary coil wound around each core captures the flux generated from the primary coil of that core. Therefore, the secondary coils are connected in series.

[0231] In FIG. 21, a single secondary coil captures flux from two cores. The configuration of FIG. 23 differs from the configuration of FIG. 21 in that the secondary coil of each core captures the flux generated from the primary coil of that core. Then, a corresponding current is generated from each core. The currents generated from each core are then added together.

[0232] FIG. 24 is a diagram illustrating an example of an FMT in which primary coils are connected in parallel to two cores and two secondary coils are connected in series.

[0233] In the FMT of Fig. 23, the secondary coils in the two cores are connected in series to produce an output. Fig. 24 is the symbol for such an FMT.

[0234] Generally, when two coils are connected in parallel or series, mutual inductance is generated between them due to magnetic flux. However, in the FMT of Fig. 24, since the two primary coils are wound around two different cores, the mutual inductance is minimized. Mutual inductance can be reduced by placing the coils or cores far apart from each other. Furthermore, for example, if toroidal cores are used, the magnetic B field is trapped within the cores, so the mutual inductance between the two coils is close to zero. Therefore, we can set the mutual inductance between the primary coils of such an FMT to zero. As we have already mentioned, in such cases, the flux generated through the parallel or series-connected coils reaches a maximum value.

[0235] FIG. 25 illustrates an example of an FMT composed of two cores. Each core has an FMI in which two inductors are connected in parallel as primary coils. Only the primary coils are shown.

[0236] FIG. 25 shows the primary coils of an FMT with two cores. In this example, it shows an FMT in which a pFMI is used on the primary side, with two inductors connected in parallel to each core. The primary coils of the two cores are connected in parallel to form the primary coils of the FMT. Of course, the pFMIs, which consist of coils connected in parallel to each core, can also be connected in series to form the primary side of the FMT.

[0237] FIG. 26 illustrates an example of an FMT composed of two cores. Each core has a pFMI in which two inductors are connected in parallel as primary coils. The two pFMIs are connected in parallel on the primary side and have two secondary coils, each secondary coil being wound around a respective core and connected in series with each other. Dots have been omitted.

[0238] The configuration of Fig. 25 can be viewed as two FMIs connected in parallel, as each toroid forms a single FMI. Therefore, this is an example of an FMT having FMIs connected in parallel on the input side. Fig. 26 shows an FMT composed of two cores. Each core has an FMI in which two inductors are connected in parallel as primary coils. There are two secondary coils, each coil wound around a core and connected in series with each other.

[0239] FIG. 27 illustrates an example of an FMT composed of two cores. Each core has a pFMI in which two inductors are connected in parallel as primary coils. There is one secondary coil, which is wound around the two cores. Dot markings have been omitted.

[0240] The secondary coil can be wound around two or more cores as in FIG. 21. FIG. 27 shows an FMT in which each primary coil is wound around a respective core and the secondary coil is wound across the two cores.

[0241] FIG. 28 illustrates an example of an FMT composed of two cores. Each core has a pFMI in which two inductors are connected in parallel as primary coils. There is one secondary coil, which is wound around the two cores. Dot markings have been omitted.

[0242] FIG. 28 shows an FMT in which each primary coil is wound around a core and the secondary coil is wound across the two cores. However, FIG. 28 differs from FIG. 27 in that two primary pFMIs are connected in series. Since both AC and DC connections are used in such a primary configuration, it can be considered an hFMI.

[0243] More than one inductor per core may be connected in parallel and / or series. And more than one core may be used to increase flux generation power. In other words, for example, in configurations such as FIGS. 26, 27, and 28, two or more cores may be used and / or two or more inductors per core may be connected in parallel and / or series.

[0244] FMTs can replace coupling inductors or transformers in circuits, particularly in switched-mode power supplies (SMPSs). This applies not only to single-phase SMPSs but also to all other variations, such as multi-phase SMPSs. Of course, when doing so, it is necessary to appropriately modify circuit components or control parts to handle the increased voltage or changing current values. By properly adjusting the component values, all control technologies used in switched-mode power supplies can be applied directly to circuits where the transformer has been replaced by an FMT.

[0245] Taking flyback converters as an example, efficiency can be improved by using FMTs not only in two-switch flyback converters, parallel flyback converters, and interleaved flyback converters, but also in various modified forms. (Reference 2: Juha Pesonen, Improving the Performance of Traditional Flyback-Topology with Two-Switch Approach, Application Report SNVA716 - July 2014, Texas Instruments.) (Reference 3: Kim, JW, Lee, IO, Moon, GW, & Park, KB (2012). Series input parallel output interleaved flyback converter with regenerative leakage inductance energy. In Conference Proceedings - 2012 IEEE 7th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2012; Vol. 2, (pp. 1347-1352), Article 6258993.)

[0246] FIG. 29 is a diagram illustrating an example of a parallel flyback converter using FMTs as part of two parallel units.

[0247] Since using FMTs increases the amount of flux, the operating period of a circuit equipped with FMTs becomes smaller than that of a circuit using a normal transformer at a given input voltage, output power, and frequency. Therefore, in a parallel flyback converter as shown in FIG. 29, the number of parallel elements can be greater than two when using FMTs. In this way, the output power of the parallel flyback converter can be maximized.

[0248] The principle of increasing flux using FMT described here can be used, for example, in pulse transformers, but is not limited to them and can be applied to all types of transformers.

[0249] Generally, FMTs can be connected to each other in various ways to form other useful FMTs. Fig. 17 shows consecutively connected FMTs forming another FMT. Fig. 26 shows two FMTs, one above and one below, connected in parallel at the input side and in series at the output side.

[0250] FIG. 30 is a diagram illustrating an example of an FMT made by connecting two FMTs of FIG. 27 in parallel on the input side and in series on the output side. Dot markings have been omitted.

[0251] There are two main methods for creating a new FMT by connecting multiple FMTs. The first method involves connecting the primary FMTs (FMIs) in parallel and / or series, forming one or more secondary coils that wrap around one or more of the cores of the FMTs, and connecting two or more such secondary coils in series to form a new secondary coil. The second method involves connecting two or more FMTs in a cascade; that is, connecting the output of one FMT to the input of another FMT to form yet another FMT. The newly formed FMT then serves as a component for forming another FMT, allowing for the recursive formation of yet another FMT. In this way, various types of FMTs can be created.

[0252] Regarding the formation of the secondary coil of a new FMT in the first method, let's take the case where the FMTs all have five cores as an example. In one example, a single coil can wrap around all five cores to form the FMT's secondary coil. In another example, one coil can wrap around two cores, another coil can wrap around two cores, and the remaining core can be wrapped by yet another coil, so that the five cores are wrapped by three coils and these coils are connected in series to form the secondary coil of the new FMT.

[0253] For example, Fig. 30 shows an FMT made by connecting two FMTs of Fig. 27 in parallel at the input side and in series at the output side. For example, if you want to connect two FMTs of Fig. 27 in series, you can do as in Fig. 17.

[0254] An FMI with multiple ports can be used on the primary side of an FMT. Thus, a single FMT can have multiple ports on the primary side and collect flux generated from various other voltages on the primary side using the secondary coil of the FMT. For example, FIG. 14 shows an FMI with multiple ports, and an FMT can be made by winding a secondary coil around its core. The flux generated by the current at each input port is combined and collected by the secondary coil.

[0255] So far, we have examined the case where the FMT has a single output. Just as a general transformer has multiple outputs by having multiple secondary coils, an FMT can also be made to have multiple outputs through multiple secondary coils.

[0256]

[0257] 3. FMT as a coupled inductor in a discontinuous conduction mode or a mode close thereto

[0258] Figure 31 is a diagram illustrating an example of a flyback converter using an FMT. is the input DC voltage, S is the switch, is a diode, is a capacitor, is the load resistance, and is the average output voltage. Subscript class represents the first and second orders, respectively. Subscript represents magnetization. Subscript and represents the upper and lower inductors, respectively. and represents current and voltage, respectively. is magnetizing inductance, and is the number of turns of the coil.

[0259] Let's consider the circuit in Fig. 31. It is a flyback converter using the FMT of Fig. 24. To simplify the problem, the inductors and It is assumed that it has the same characteristic values. First, we analyze the circuit when it is in continuous conduction mode and steady state.

[0260]

[0261] Ratio of the number of wound It is as follows.

[0262]

[0263] When switch S is turned on, diode It does not conduct. Assuming the mutual inductance between the input coils of the FMT is zero,

[0264]

[0265] In the above, D is the duty cycle and T is the period. Diode Note that is in italics, but operation cycle D is not. While switch S is on This is the amount that has increased.

[0266] When switch S is turned off, assuming the diode is an ideal type,

[0267]

[0268] Here, is while the switch is off This is the amount that has increased.

[0269] From the voltage balance condition of an inductor, the following holds:

[0270]

[0271] Therefore, it can be seen that when the FMT in Fig. 24 is used, the output voltage of the circuit is twice that of a circuit using a standard coupled inductor. (Reference 4: Mohammad Kamil, AN1114, Switch Mode Power Supply (SMPS) Topologies (Part I), Microchip Technology Inc., 2017.)

[0272] In a flyback converter circuit, energy is stored in the core of the FMT while switch S is on, and that energy is transferred to the load while the switch is off. Therefore, in this circuit, the FMT operates as a coupled inductor.

[0273] In the continuous conduction mode of a flyback converter, the magnetizing current is incomplete because the demagnetization of the core is incomplete. It is related to the output current. Given the circuit configuration and operating cycle, in continuous conduction mode, the magnetization current is proportional to the output current. As the output current decreases, the de-energization of the core progresses further, and if the load is sufficiently light, the de-energization eventually becomes complete, and the circuit enters discontinuous conduction mode.

[0274] FIG. 32 is a diagram illustrating an example of the current flowing through one primary coil while the switch is turned on in the continuous conduction mode of the circuit of FIG. 31. This is the maximum value of the magnetization current while the switch is turned on. is the value of the current that generates flux remaining in the core depending on the output side load.

[0275] FIG. 32 shows the current flowing through one primary coil while the switch is turned on in the continuous conduction mode of the circuit of FIG. 31. Here, This is the maximum value of the magnetization current while the switch is turned on. It is a current value determined by the output load, and it generates flux that remains in the core even after the switch is turned off. Input current It is related to the magnetization current as follows.

[0276]

[0277] Here, <> represents the average value.

[0278] When the circuit is in discontinuous conduction mode (including boundary conduction mode), the magnetization current is no longer related to the output current or load, and the peak value of the magnetization current while the switch is on It is as follows.

[0279]

[0280] FMI, which increases flux, involves connecting inductors in parallel or series, and is based on the relationship between voltage and the rates of change of the inductor's inductance and current. This is exactly the same as the equation above. As we have already mentioned, it was assumed that the voltage is applied after the core's demagnetization is complete, which is equivalent to the conditions in the discontinuous conduction mode of a flyback converter.

[0281] Therefore, the change in magnetization current is related to the increase in the flux of the FMT and is not related to the amount of flux remaining in the core. The greater the proportionality between the amount of flux increased in the core while the switch is on and the total amount of flux in the core, the greater the effect of using the FMT in the circuit, and the higher the efficiency of the circuit. Approximate effectiveness of the FMT in the circuit of Fig. 31 It can be defined as follows.

[0282]

[0283] In other words,

[0284]

[0285] It can be seen that the effect of FMT in the circuit is greatest when it is in discontinuous conduction mode (including boundary conduction mode).

[0286] Now, the average value of the input current in the circuit of Fig. 31 in discontinuous conduction mode is as follows.

[0287]

[0288] In other words, in the discontinuous conduction mode of a flyback converter circuit, the input current supplied by the power source is independent of the load. It is related to the primary-side parameters of the inductor coupled to the power source, namely the input voltage and magnetization inductance. Otherwise, it is involved with common parameters, namely the operating period and switching frequency. This is a characteristic of the discontinuous conduction mode (including the boundary conduction mode) in a flyback converter circuit.

[0289] In circuits where the transformer does not operate as a coupled inductor, the input current is influenced by the load-side parameters. For example, in a forward converter, the total current flowing through the primary coil of the transformer is the sum of the magnetization current and the current reflected from the load-side inductor to the primary side. (Reference 4: Mohammad Kamil, AN1114, Switch Mode Power Supply (SMPS) Topologies (Part I), Microchip Technology Inc., 2017.) Therefore, in such cases, the primary coil supplies the necessary power by “observing” the situation on the secondary side. In such cases, the effectiveness of the FMT is not maximized.

[0290] However, when the transformer operates as an inductor coupled with the primary coil in discontinuous conduction mode in a flyback converter circuit, the primary coil cannot know the conditions on the load side; therefore, it supplies current based on the primary parameters, operating period, and switching frequency regardless of the load.

[0291] Therefore, an FMT that increases flux can be used most effectively in circuits operating as a coupled inductor in discontinuous conduction mode. The principles presented here can also be applied to other types of flyback converter configurations. For example, a synchronous flyback converter may have a forced continuous conduction mode similar to discontinuous conduction mode, where the magnetization current can be negative while the switch is off. Even in such cases, the efficiency of the circuit can be increased using an FMT. Another example where an FMT can be effectively used is the quasi-resonant (QR) mode flyback converter, which is a type of discontinuous conduction mode. Another example is the valley switching mode, which is also a type of discontinuous conduction mode. In such cases as well, as long as the input current is not dependent on the load, an FMT can be used to increase the efficiency of the circuit.

[0292] In any circuit, the effectiveness of the FMT depends on the magnetization current while the switch is on, and its effectiveness is greatest when the magnetization current is not related to the load.

[0293] The more the input current of a circuit consists solely of the magnetization current of the coupled inductor or transformer while the switch is on, and the less the magnetization current is related to the load, the more effectively the FMT can be used to increase the efficiency of the circuit.

[0294] A transformer can be viewed as consisting of a magnetizing inductor and an ideal transformer. The input current of a transformer or coupled inductor consists of the magnetizing current flowing through the magnetizing inductor and the current flowing through the primary coil of an ideal transformer. Generally, the current flowing through the primary coil of a transformer is related to the load. On the other hand, when the circuit is in discontinuous conduction mode, the magnetizing current is not related to the load. When there is no current flowing through the primary coil and only the magnetizing current flows, and the circuit is in discontinuous conduction mode, the input current of the circuit is not related to the load.

[0295] In conclusion, when a transformer or coupled inductor in a circuit accepts input power from a power source and outputs it, the less the input current to the transformer or coupled inductor is dependent on the load, the more the efficiency of the circuit can be increased by replacing the transformer or coupled inductor with an FMT.

[0296]

[0297] 4. Experiment

[0298] FIG. 33 is a diagram showing an example of the connection of the secondary sides of two transformers on the LM3481-FlybackEVM board.

[0299] The purpose of this experiment is to demonstrate that an FMT can increase the efficiency of a circuit. First, the efficiency was measured with a single transformer on the Texas Instruments LM3481-FlybackEVM board left as is. Then, a transformer of the same type was stacked on top of the first transformer to create a single FMT consisting of two transformers, as shown in Fig. 24. Fig. 33 shows the two transformers connected. Finally, the efficiency of the board equipped with the FMT created in this way was measured.

[0300] The board is designed to stably output a 12-volt output voltage. Efficiency was measured while varying the load from 300 ohms to 10 ohms. Efficiency was also measured while varying the input voltages. Table 1 shows the experimental results when the input voltage is 12 volts.

[0301]

[0302] Table 1. Efficiency measurement of the LM3481-FlybackEVM board at an input voltage of 12 volts

[0303] The efficiency improvement is the value obtained by subtracting the efficiency of the original configuration from the efficiency of the configuration with FMT, and it can be seen that these values ​​are positive. This demonstrates that FMT is useful for improving the efficiency of the circuit.

[0304] Figure 34 is a diagram showing an example of efficiency improvement according to various output currents and various input voltages.

[0305] Figure 34 shows a graph of efficiency improvement as output currents change by changing the load. As the output current decreases, the inductor current also decreases, so it moves more towards a discontinuous conduction mode, and it can be seen that the efficiency improvement is more noticeable.

[0306] The present invention has been described above with reference to its preferred embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

Claims

1. One or more cores; and A flux-increasing inductor characterized by comprising a plurality of coils connected in parallel and / or series, wrapping around the one or more of the above-mentioned cores.

2. In Paragraph 1, A flux-increasing inductor characterized in that the above-mentioned core is in the form of a closed loop or an open loop.

3. In Paragraph 1, A flux-increasing inductor characterized by having a single magnetic core and a plurality of coils surrounding the single magnetic core.

4. In Paragraph 1, There are multiple souls, and A flux-increasing inductor characterized by the plurality of coils wrapping the plurality of magnetic cores.

5. In Paragraph 1, A flux-increasing inductor characterized by the fact that the direction of the flux generated by the plurality of coils is the same.

6. In Paragraph 1, A flux-increasing inductor characterized in that the voltage waves applied to at least two of the plurality of coils are different from each other, while the direction of the flux coming from the plurality of coils is the same.

7. A flux-increasing inductor in a recursive configuration formed by connecting the flux-increasing inductors of claim 1 in series and / or parallel.

8. In a flux-increasing transformer comprising the flux-increasing inductor of claim 1, Primary coils implemented with the plurality of coils of the above flux-increasing inductor; and A flux-increasing transformer characterized by including a secondary coil that wraps at least one core(s) of the flux-increasing inductor.

9. In Paragraph 8, A flux increasing transformer characterized in that the primary coils described above surround multiple magnetic cores and include multiple coils connected in parallel and / or series.

10. In Paragraph 9, A flux increasing transformer characterized in that the secondary coil comprises a plurality of coils connected in series, which surround the plurality of magnetic cores.

11. A flux-increasing transformer of recursive configuration in which the output of the flux-increasing transformer of claim 8 is cascaded as the input of another flux-increasing transformer.

12. A switch-mode power supply comprising the flux-increasing transformer described in Clause 8.

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