Three-inductor coupling integrated structure

Abstract

The invention provides a three-inductor coupling integrated structure, which is applied to the technical field of power electronics, and comprises a first coupling inductor, a second coupling inductor and a third coupling inductor which are arranged in an upper and lower layer stacking manner, a spiral coil structure is adopted, and the spiral winding direction of the spiral coil structure is matched based on the mutual inductance direction; the first coupling inductor, the second coupling inductor and the third coupling inductor form three groups of mutual inductance relations through magnetic coupling. Wherein the three groups of mutual inductance relations, the self-inductance of the first coupling inductor, the self-inductance of the second coupling inductor and the self-inductance of the third coupling inductor meet a preset constraint relation so as to improve the power density; according to the invention, current reduction, electromagnetic interference reduction and total current reduction of a single inductor in the circuit can be realized, and the power density of the circuit is improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular, to a three-inductor coupled integrated structure. Background Art

[0002] The interleaved parallel technology can not only increase the power level of the converter, reduce the input and output current ripples, but also improve the dynamic response of the converter. The coupled inductor technology reduces the volume of magnetic components in the circuit and realizes the automatic current sharing of the converter.

[0003] However, in an interleaved parallel circuit, when the like-named terminals of two inductors are connected, the mutual inductance is positive, the equivalent inductance on each phase branch decreases, the individual inductor current volatility increases, resulting in an increase in the turn-off loss of the switching device; when the unlike-named terminals of two inductors are connected, although the equivalent inductance on each phase branch will increase and the volatility of the individual inductor current will decrease, this does not mean that the system performance has been improved, because there will be an equivalent negative inductance in the parallel loop, which will lead to an increase in the volatility of the total current. Correspondingly, to maintain the same total current volatility, both inductors need to be increased, which is contrary to the goal of reducing the inductor volume and improving the system power density through the interleaved parallel and magnetic coupling technologies. Summary of the Invention

[0004] The present invention provides a three-inductor coupled integrated structure to solve the defect of power reduction caused by the mutual inductance of inductors in a two-phase interleaved parallel circuit in the prior art, and to realize the reduction of both the individual inductor current and the total current in the circuit, and the improvement of the circuit power density.

[0005] The present invention provides a three-inductor coupled integrated structure, including the following modules.

[0006] A first coupled inductor, a second coupled inductor, and a third coupled inductor, wherein the first coupled inductor, the second coupled inductor, and the third coupled inductor are arranged in a stacked manner up and down, adopting a spiral coil structure and the spiral winding direction of the spiral coil structure is set based on the mutual inductance direction matching; mutual inductance relationships are respectively formed between the first coupled inductor, the second coupled inductor, and the third coupled inductor through magnetic coupling, including: the mutual inductance between the first coupled inductor and the second coupled inductor, the mutual inductance between the first coupled inductor and the third coupled inductor, and the mutual inductance between the second coupled inductor and the third coupled inductor; wherein, the three mutual inductance relationships and the self-inductance of the first coupled inductor, the self-inductance of the second coupled inductor, and the self-inductance of the third coupled inductor satisfy a preset constraint relationship to improve the power density.

[0007] A three - inductance coupling integrated structure provided by the present invention, wherein the first coupling inductor, the second coupling inductor, and the third coupling inductor have the same coupling inductor structure; the coupling inductor structure from top to bottom is in turn: a first back core, a multi - layer and multi - turn planar coil, and a second back core.

[0008] A three - inductance coupling integrated structure provided by the present invention, the coupling inductor structure further includes: a first side core located below the first back core, a second side core located above the second back core; a first central core and a second central core, wherein the first central core is arranged closely adjacent to the first back core, and the second central core is arranged closely adjacent to the second back core; the first central core and the second central core are in close contact or at a preset distance.

[0009] A three - inductance coupling integrated structure provided by the present invention, the multi - layer and multi - turn planar coil includes: a first inductor coil, a second inductor coil, and a third inductor coil.

[0010] A three - inductance coupling integrated structure provided by the present invention, the winding direction of the multi - layer and multi - turn planar coil is clockwise or counterclockwise; the winding direction is used to adjust the mutual inductance polarity between the first inductor coil, the second inductor coil, and the third inductor coil.

[0011] A three - inductance coupling integrated structure provided by the present invention, the three - inductance coupling integrated structure is applied to a two - phase interleaved parallel circuit, The two - phase interleaved parallel circuit at least includes: a two - phase interleaved parallel Buck circuit and a two - phase interleaved parallel Boost circuit.

[0012] A three - inductance coupling integrated structure provided by the present invention, the terminal voltage of the first coupling inductor is: The terminal voltage of the second coupling inductor is: The terminal voltage of the third coupling inductor is: Wherein, represents the terminal voltage of the first coupling inductor, represents the terminal voltage of the second coupling inductor, represents the terminal voltage of the third coupling inductor, represents the self - inductance of the first coupling inductor, represents the self - inductance of the second coupling inductor, represents the self - inductance of the third coupling inductor, represents the mutual inductance between the first coupled inductor and the third coupled inductor, represents the mutual inductance between the first coupled inductor and the second coupled inductor, represents the mutual inductance between the second coupled inductor and the third coupled inductor, represents the inductor current of the first coupled inductor, represents the inductor current of the second coupled inductor, represents time.

[0013] According to a three - inductor coupled integration structure provided by the present invention, when the same - name terminals of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are the same.

[0014] According to a three - inductor coupled integration structure provided by the present invention, when the different - name terminals of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are opposite.

[0015] In the three - inductor coupled integration structure provided by the present invention, the upper - layer and lower - layer stacked arrangement among the first coupled inductor, the second coupled inductor, and the third coupled inductor makes full use of space, reduces the physical size of the integration structure. At the same time, through the optimized design of mutual inductance and self - inductance, the power output ability per unit volume is improved. The matching setting of the spiral winding direction enhances the magnetic coupling strength, enabling a higher power density to be achieved under the same volume. The balanced design of the three groups of mutual inductance relationships effectively suppresses the non - uniform distribution of the magnetic field, reduces electromagnetic radiation, and decreases the interference to the external circuit. The matching of the winding direction of the spiral coil structure further optimizes the magnetic field path, avoids local magnetic field concentration, and thus reduces the level of electromagnetic interference. The self - inductance and mutual inductance of the three coupled inductors satisfy a preset constraint relationship to improve the power density, providing a clear direction for parameter optimization, so that the structure can adapt to different application scenarios and performance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art one by one. Obviously, the following - described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 is a schematic diagram of a two - phase interleaved parallel Buck circuit provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the equivalent circuit when the corresponding terminals are coupled according to the present invention.

[0019] Figure 3 It is a schematic diagram of the three-inductor coupling integrated structure according to the present invention.

[0020] Figure 4 It is the schematic diagram of the coupling inductor principle according to the present invention.

[0021] Figure 5 It is a schematic diagram of the structure when applied to a two-phase interleaved parallel Buck circuit according to the present invention.

[0022] Figure 6 It is a schematic diagram of the driving signal and the inductor current waveform according to the present invention.

[0023] Figure 7 It is a schematic diagram of the relationship between the output current fluctuation amplitude and the mutual inductance between inductors according to the present invention.

[0024] Figure 8 It is a schematic diagram of the traditional two-phase interleaved parallel Boost circuit according to the present invention.

[0025] Figure 9 It is a schematic diagram of the two-phase interleaved parallel Boost circuit applying three coupled inductors according to the present invention. Detailed implementation manners

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0027] Unless otherwise defined, technical terms or scientific terms used in this disclosure shall have the ordinary meanings as understood by those of ordinary skill in the art to which this disclosure pertains. The terms "first", "second" and similar words used in this disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a", "an" or "the" do not denote a quantity limitation, but mean that there is at least one. The numbers in the drawings of the specification only represent the distinction of each functional component or module, and do not represent the logical relationship between the components or modules. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Words such as "upper", "lower", "left" and "right" are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0028] The interleaved parallel technology can not only increase the power rating of the converter, reduce the input and output current ripples, but also improve the dynamic response of the converter. The coupled inductor technology reduces the volume of magnetic components in the circuit and realizes the automatic current sharing of the converter. Therefore, it has been widely applied in various converters and voltage regulators such as Buck, Boost and Forward.

[0029] For a two-phase interleaved parallel converter, the coupling methods of inductors can be divided into two types: forward coupling and reverse coupling. In the related technologies, detailed analysis and comparison have been made for these two coupling methods, and it is pointed out that the reverse coupling method can increase the steady-state equivalent inductance and reduce the dynamic equivalent inductance, meeting the requirements of low ripple in the steady state and fast response in the dynamic state of the converter.

[0030] Reference Figure 1 , Figure 1 is the schematic diagram of the two-phase interleaved parallel Buck circuit provided by the present invention.

[0031] Taking the two-phase interleaved parallel Buck circuit as an example, when there is coupling between two inductors, the schematic diagram of the two-phase interleaved parallel Buck circuit is as Figure 1 shown. Wherein U in is the input voltage, C 1 is the input terminal support capacitor, S 1 and S 2 are switching devices, D 1 and D 2 are freewheeling diodes, L 1 and L 2 are the self-inductances of the inductors, Mis the mutual inductance between two inductors, C 2 is the output point support capacitor, R is the load resistor, i 1 and i 2 are the inductor currents, i L is the synthesized inductor current, i O is the output current, i C is the current of the output terminal support capacitor.

[0032] Reference Figure 2 , Figure 2 is a schematic diagram of the equivalent circuit when the same-named terminals are coupled provided by the present invention.

[0033] In the two-phase interleaved parallel Buck circuit, the driving signal phases of S1 and S2 differ by 180°, Figure 1 which can be equivalent to Figure 2 the circuit shown.

[0034] Among them, when the same-named terminals of the two inductors are connected, the mutual inductance M of the inductors is positive, and the equivalent inductance ( L 1 - M and L 2 - M ) on each phase branch decreases, and the fluctuation rate of the single inductor current i 1 and i 2 increases, resulting in an increase in electromagnetic interference (EMI) and an increase in the turn-off loss of the switching device; when the different-named terminals of the two inductors are connected, the equivalent inductance on each phase branch increases, and the fluctuation rate of the single inductor current i 1 and i 2 decreases, but due to the existence of the equivalent negative inductance M in the loop after parallel connection, the total current fluctuation rate increases. Correspondingly, to maintain the same total current fluctuation rate, L 1 and L 2 need to increase, which is contrary to the goal of reducing the inductor volume and improving the system power density through interleaved parallel and magnetic coupling technologies.

[0035] To solve the above contradictions, the present invention proposes a novel two-phase interleaved parallel circuit and coupled inductor structure to achieve the goals of reducing both the single inductor current and the total current, reducing electromagnetic interference, and improving power density.

[0036] Reference Figure 3 , Figure 3 is a schematic diagram of the three-inductor coupled integration structure provided by the present invention, which includes: the first coupled inductor L 1, the second coupled inductor L2 and the third coupling inductor L 3. The mutual inductance between the first coupling inductor and the second coupling inductor is M 12 . The mutual inductance between the first coupling inductor and the third coupling inductor is M 13 . The mutual inductance between the second coupling inductor and the third coupling inductor is M 23 .

[0037] The first coupling inductor, the second coupling inductor, and the third coupling inductor are arranged in a stacked manner, with the first coupling inductor, the second coupling inductor, and the third coupling inductor stacked one above the other. They adopt a spiral coil structure, and the winding direction of the spiral coil structure is set based on the mutual inductance direction matching; Three groups of mutual inductance relationships are formed between the first coupling inductor, the second coupling inductor, and the third coupling inductor through magnetic coupling, including: the mutual inductance between the first coupling inductor and the second coupling inductor, the mutual inductance between the first coupling inductor and the third coupling inductor, and the mutual inductance between the second coupling inductor and the third coupling inductor; Among them, the three groups of mutual inductance relationships, the self-inductance of the first coupling inductor, the self-inductance of the second coupling inductor, and the self-inductance of the third coupling inductor satisfy a preset constraint relationship to improve the power density. According to a three-inductor coupling integrated structure provided by the present invention, the first coupling inductor, the second coupling inductor, and the third coupling inductor have the same structure; Through the embodiments of the present invention, the stacked arrangement of the first coupling inductor, the second coupling inductor, and the third coupling inductor makes full use of space, reduces the physical size of the integrated structure. At the same time, through the optimized design of mutual inductance and self-inductance, the power output ability per unit volume is improved. The matching setting of the winding direction enhances the magnetic coupling strength, enabling a higher power density to be achieved under the same volume. The balanced design of the three groups of mutual inductance relationships effectively suppresses the non-uniform distribution of the magnetic field, reduces electromagnetic radiation, and reduces interference to external circuits. The winding direction matching of the spiral coil structure further optimizes the magnetic field path, avoids local magnetic field concentration, and thus reduces the level of electromagnetic interference. The self-inductance and mutual inductance of the three coupling inductors satisfy a preset constraint relationship to improve the power density, providing a clear parameter optimization direction, enabling the structure to adapt to different application scenarios and performance requirements.

[0038] According to a three-inductor coupling integrated structure provided by the present invention, the first coupling inductor, the second coupling inductor, and the third coupling inductor have the same coupling inductor structure; The coupling inductor structure from top to bottom is: the first back core, the multi-layer multi-turn planar coil, and the second back core.

[0039] In the embodiment of the present invention, the first coupled inductor and the second coupled inductor adopt exactly the same magnetic core and coil design to ensure parameter consistency (such as self-inductance, mutual inductance, and coupling coefficient), avoid current imbalance due to structural differences, and improve system reliability.

[0040] The structure of the third coupled inductor is consistent with that of the first coupled inductor and the second coupled inductor, but the coil parameters need to be determined according to the actual application scenario. For example, due to different currents, the wire diameters will be different, and the number of turns and layers may also be different. It is necessary to coordinately optimize the coil parameters of the third coupled inductor based on comprehensive considerations such as the total inductor current fluctuation rate, the current fluctuation rate of a single inductor, the total power density, and the leakage magnetic intensity.

[0041] The upper and lower layers of back cores (the first back core and the second back core) are symmetrically distributed to form a closed magnetic circuit, reduce magnetic leakage, improve core utilization, and reduce magnetic resistance loss.

[0042] According to a three-inductor coupled integrated structure provided by the present invention, the above-mentioned coupled inductor structure further includes: A first side magnetic core located below the first back magnetic core, and a second side magnetic core located above the second back magnetic core; A first central magnetic core and a second central magnetic core, wherein the first central magnetic core and the first back magnetic core are arranged closely together, and the second central magnetic core and the second back magnetic core are arranged closely together; The first central magnetic core and the second central magnetic core are in close contact or at a preset distance.

[0043] In the embodiment of the present invention, the back core (first / second back core) serves as the main path of magnetic flux and undertakes most of the magnetic energy storage and transmission. By being close to the central core (first / second central core), a low magnetic resistance channel is formed to reduce the core loss.

[0044] The first side magnetic core is located below the first back magnetic core to guide the bottom edge magnetic flux backflow to prevent leakage magnetic flux from spreading to the external circuit; the second side magnetic core is located above the second back magnetic core to suppress the top magnetic flux from leaking out.

[0045] When the first central magnetic core is in close contact with the second central magnetic core, a continuous magnetic circuit is formed, and the mutual inductance coefficient is maximized to improve the coupling efficiency; when the first central magnetic core is in close contact with the second central magnetic core at a preset distance, the magnetic circuit magnetic resistance is controlled by adjusting the distance, and the inductance value is dynamically adjusted to adapt to different switching frequency requirements.

[0046] Through the embodiments of the present invention, through the multi-dimensional magnetic circuit design of the back magnetic core-side magnetic core-central magnetic core, efficient magnetic flux control, dynamic parameter adjustment, excellent heat dissipation and high-frequency low-loss characteristics are achieved.

[0047] A three - inductance coupled integrated structure provided by the present invention, the multi - layer and multi - turn planar coil includes: a first inductance coil, a second inductance coil, and a third inductance coil.

[0048] The multi - turn design of the multi - layer and multi - turn planar coil improves the inductance value within a limited area and reduces the inductance volume. The combined uniform winding of the planar coil and the symmetric layout of the back core make the magnetic flux density distribution uniform, avoiding the risk of local saturation and improving the power handling capacity.

[0049] Reference Figure 4 , Figure 4 is a schematic diagram of the coupled inductance structure provided by the present invention. Among them, it includes (a) the external shape of the coupled inductance, and (b) the internal structure of the coupled inductance. Among them, the internal structure of the coupled inductance includes, from top to bottom in sequence: (the first) back core, (the first) side core, (the first) central core, inductance 1 coil (i.e., the first inductance coil), inductance 3 coil (i.e., the third inductance coil), inductance 2 coil (i.e., the second inductance coil), (the second) central core, (the second) side core, (the second) back core.

[0050] In an embodiment of the present invention, the coupled inductance structure includes three multi - layer and multi - turn planar coils stacked one above the other, and cores are laid at the bottom, side, and center, which play the role of concentrating magnetic flux and shielding leakage magnetic flux.

[0051] Among them, the side and central cores are not necessary and can be omitted according to requirements such as weight - power density and leakage magnetic flux intensity. The central core is arranged closely against the back core, and there is either a close contact or a certain distance between the two central cores.

[0052] A three - inductance coupled integrated structure provided by the present invention, the winding direction of the multi - layer and multi - turn planar coil is clockwise or counter - clockwise; the winding direction is used to adjust the mutual inductance polarity between the first inductance coil, the second inductance coil, and the third inductance coil.

[0053] By changing the winding direction of the planar coil, that is, clockwise winding or counter - clockwise winding when looking down, forward coupling or reverse coupling between the planar coils can be achieved. There is mutual inductance between the three planar coils. When the requirement for the total inductance current volatility is known, the self - inductance and mutual inductance values of the inductance can be designed to achieve the comprehensive optimization of high efficiency, high power density, and low EMI of the circuit.

[0054] A three - inductance coupled integrated structure provided by the present invention, the three - inductance coupled integrated structure is applied to a two - phase interleaved parallel circuit, and the two - phase interleaved parallel circuit at least includes: a two - phase interleaved parallel Buck circuit and a two - phase interleaved parallel Boost circuit.

[0055] Reference Figure 5 , Figure 5It is a schematic structural diagram provided by the present invention when applied to a two-phase interleaved parallel Buck circuit, which includes the following components.

[0056] Input voltage U in , which is used to provide a DC input power supply; Input terminal support capacitor C 1, which is connected in parallel between the positive and negative poles of the input voltage U in , and is used to suppress the input high-frequency ripple; First switch S 1 and second switch S 2, the input terminal of the first switch S 1 and the input terminal of the second switch S 2 are connected in parallel to the positive pole of the input voltage U in , the output terminal of the first switch S 1 and the output terminal of the second switch S 2 are respectively connected to one end of the first coupled inductor L 1 and the second coupled inductor L 2, and the driving signals of the first switch S 1 and the second switch S 2 have a phase difference of 180°; First freewheeling diode D 1 and second freewheeling diode D 2, the first freewheeling diode D 1 is connected in parallel between the output terminal of the first switch S 1 and the ground, and the second freewheeling diode D 2 is connected in parallel between the output terminal of the second switch S 2 and the ground, and is used to provide an inductor current freewheeling path during the switch-off period; First coupled inductor L 1 and second coupled inductor L 2 are respectively connected in series to the output terminals of the first switch S 1 and the second switch S 2, and the first coupled inductor L 1 and the second coupled inductor L 2 achieve mutual inductance through magnetic core coupling, and control forward or reverse coupling by adjusting the coil winding direction; Third coupled inductor L 3, forms mutual inductance with the first coupled inductor L 1 and the second coupled inductor L 2 through magnetic core coupling, and is connected to the output node; Output terminal support capacitor C 2, which is connected in parallel between the output node and the ground, is used to filter out the high-frequency ripple of the synthesized inductor current and output a DC voltage; Load resistance R , which is connected in parallel across the output terminal support capacitor C at both ends of 2, serving as the target load for energy transmission.

[0057] Among them, i 1 represents the first coupled inductor L the inductor current of 1, i 2 represents the second coupled inductor L the inductor current of 2, i L represents the synthesized inductor current, i O represents the output current, i C represents the current of the output terminal support capacitor.

[0058] In the embodiment of the present invention, the input voltage provides a stable DC input power supply for the circuit, serving as the initial source of energy transmission.

[0059] The input terminal support capacitor is used to suppress the input high-frequency ripple: absorb the sudden change of the input current caused by the switch action (on / off), and reduce the input voltage fluctuation. And provide instantaneous energy buffering: when the switch switches at high frequency, provide transient current for the input side to reduce the impact on the previous-stage power supply.

[0060] The first switch and the second switch are used for interleaved control of energy transfer: driven by a 180° phase difference (complementary conduction), so that the ripples of the two-phase inductor currents ( i 1, i 2) cancel each other out, reduce the output current ripple ( i O ), and adjust the power transmission path.

[0061] The first freewheeling diode and the second freewheeling diode are used to provide a low-impedance loop for the inductor current when the first switch and the second switch are turned off, to avoid voltage spikes from damaging the switching devices.

[0062] The first coupled inductor and the second coupled inductor are used for energy storage and transfer: through the periodic energy storage (charging when conducting) and energy release (discharging when turning off) of the switch action, voltage conversion is achieved. When coupled in the forward direction (same name terminals), the cancellation effect of the two-phase current ripple is enhanced, reducing the output ripple; when coupled in the reverse direction (opposite name terminals), the fluctuation of the single-phase inductor current is reduced, reducing the device stress.

[0063] The third coupled inductor is used for energy synthesis and transfer. It receives the magnetic flux changes of the first coupled inductor and the second coupled inductor through magnetic core coupling, synthesizes the total inductor current, and transfers it to the output terminal. Utilize the mutual inductance characteristic to further suppress the high-frequency ripple (cooperate with the output point support capacitor).

[0064] The output terminal support capacitor is used to filter out high-frequency ripples, absorb the remaining high-frequency components of the synthetic inductor current, ensure the stability of the output voltage, maintain the dynamic response, and provide instantaneous energy compensation during load mutation.

[0065] Through the embodiments of the present invention, through interleaved parallel switching control, three-inductor magnetic coupling design and multi-stage filtering, efficient and low-ripple energy conversion is achieved.

[0066] By using the first switch and the second switch and controlling them with drive signals having a 180° phase difference, efficient conversion of input energy can be achieved. The phase difference control helps to reduce the fluctuations of the input and output currents; the input terminal support capacitor is connected in parallel between the positive and negative poles of the input voltage, effectively suppressing the high-frequency ripples at the input terminal; the first freewheeling diode and the second freewheeling diode are provided to provide a freewheeling path for the inductor current during the turn-off of the switch; the first coupling inductor and the second coupling inductor achieve mutual inductance through magnetic core coupling. This design can enhance the interaction between the inductors, improve the power density and efficiency of the circuit; the third coupling inductor forms mutual inductance with the first coupling inductor and the second coupling inductor through magnetic core coupling and is connected to the output node, which helps to synthesize a stable inductor current and reduce the output fluctuations; the output terminal support capacitor is connected in parallel between the output node and the ground, further filtering out the high-frequency ripples of the synthetic inductor current to ensure a small volatility of the output DC voltage; the load resistor is connected in parallel across the output terminal support capacitor and serves as the target load for energy transfer, enabling the circuit to adapt to different load requirements and providing stable output voltage and current.

[0067] According to a three-inductor coupling integrated structure provided by the present invention, the terminal voltage of the first coupling inductor is: The terminal voltage of the second coupling inductor is: The terminal voltage of the third coupling inductor is: Wherein, represents the terminal voltage of the first coupling inductor, represents the terminal voltage of the second coupling inductor, represents the terminal voltage of the third coupling inductor, represents the self-inductance of the first coupling inductor, represents the self-inductance of the second coupling inductor, represents the self-inductance of the third coupling inductor, represents the mutual inductance between the first coupling inductor and the third coupling inductor, represents the mutual inductance between the first coupling inductor and the second coupling inductor, represents the mutual inductance between the second coupled inductor and the third coupled inductor, represents the inductor current of the first coupled inductor, represents the inductor current of the second coupled inductor, represents time.

[0068] Reference Figure 6 , Figure 6 is a schematic diagram of the drive signal and the inductor current waveform provided by the present invention.

[0069] In the two-phase interleaved parallel Buck circuit, the drive signals of the first switch and the second switch are 180° out of phase. The drive signals, the inductor currents, and the combined inductor current waveform are as Figure 6 shown. The duty cycle D = U O / U in , where U O is the output voltage, U in is the input voltage. Parasitic parameters of components are ignored during theoretical derivation, including the parasitic capacitance and parasitic resistance of the power switch, the parasitic resistance of the diode, etc.

[0070] Here, if 0 < D < 1 / 2, from 0 to the first time point ( t 1 ), the first switch is in the on state and the second switch is in the off state; from the first time point to the half-cycle point (of the drive signal), both the first switch and the second switch are in the off state; from the half-cycle point (T / 2) to the second time point ( t 2 ), the first switch is in the off state and the second switch is in the on state; from the second time point to the full-cycle point (T) of the drive signal, both the first switch and the second switch are in the off state.

[0071] If 1 / 2 < D < 1, from 0 to the first time point ( t 1 ), both the first switch and the second switch are in the on state; from the first time point to the half-cycle point of the drive signal, the first switch is in the on state and the second switch is in the off state; from the half-cycle point (T / 2) to the second time point ( t 2 ), both the first switch and the second switch are in the on state; from the second time point to the full-cycle point (T) of the drive signal, the first switch is in the off state and the second switch is in the on state.

[0072] According to the circuit law, the following equations can be obtained: Among them, represents the terminal voltage of the first coupled inductor, represents the terminal voltage of the second coupled inductor, represents the terminal voltage of the third coupled inductor. Further simplification can obtain: For the specific meanings of the various parameters in the formula, reference can be made to the above embodiments, which will not be elaborated herein in this application.

[0073] When 0 < D < 1 / 2, the fluctuation amplitude of the inductor current can be obtained by the following formula: When 0 < t < DT ( t 1 =DT ), The fluctuation amplitude of the current of the first coupled inductor is: The synthesized fluctuation amplitude of the inductor current is: When T / 2 < t < ( T / 2 + DT ), t 2 = T / 2 + DT ), following a similar process, the fluctuation amplitude of the current of the second coupled inductor can be derived as: When 1 / 2 < D < 1, the fluctuation amplitude of the inductor current can be obtained by the following formula: When t 1 < t < T / 2 ( t 2 =DT= T / 2 + t 1), the fluctuation amplitude of the current of the second coupled inductor is: The synthesized fluctuation amplitude of the inductor current is: t 2 <t<T When, following a similar process, the fluctuation amplitude of the current of the first coupled inductor can be derived as: As can be seen from the above formula, compared with the Figure 1 two-inductor coupling method shown, the three-inductor coupling structure proposed by the present invention introduces three additional variables, namely L 3 , M 12 and M 23 , which improves the system design freedom and can achieve the goals of reducing both the single inductor current and the total current, and reducing EMI. At the same time, compared with the two-inductor coupling structure, there is only one more L 3 coil. Generally, the cross-sectional area of the planar inductor coil is much larger than the wire diameter. Therefore, the inductor only increases in size in the vertical direction, and the inductor volume does not increase significantly with the increase in the number of inductors. Thus, the goal of improving the power density can be achieved.

[0074] Taking the parameters shown in Table 1 as an example, the relationship between the output current fluctuation amplitude and the mutual inductance M between the coupled inductors is calculated as Figure 7 shown.

[0075] Table 1

[0076] According to the three-inductor coupling integration structure provided by the present invention, when the same-named terminals of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are the same.

[0077] Referring to Figure 7 , Figure 7 is a schematic diagram of the relationship between the output current fluctuation amplitude and the mutual inductance between the inductors provided by the present invention.

[0078] Among them, when the mutual inductance M is negative, it indicates that the different-named terminals are coupled. To achieve current sharing between two phases, let M 13 (the mutual inductance between the first coupled inductor and the third coupled inductor) and M 23 (the mutual inductance between the second coupled inductor and the third coupled inductor) have the same absolute value. When L 1 (the first coupled inductor) and L 2 (the second coupled inductor) are coupled with the same-named terminals, that is, M 12 > 0, M 12 (the mutual inductance between the first coupled inductor and the second coupled inductor) and M 23 are in agreement; otherwise,M 12 is contrary to M 23 conformance.

[0079] According to the three - inductance - coupled integrated structure provided by the present invention, when the opposite - named ends of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are opposite.

[0080] As can be seen from the figure M 12 it has a significant impact on the inductor current and the total current, and the total current volatility decreases with M 12 the increase, but the volatility of a single inductor also increases. L 1 and L 2 is coupled with L 3 the third coupled inductor (the third coupled inductor), whether it is the current of a single inductor or the volatility of the total current, both decrease with M 13 the increase; and compared with the same - named - end coupling, when L 1 is coupled with L 2 the opposite - named ends are coupled, at the cost of only a slight increase in the total current fluctuation, a significant reduction in the current fluctuation of a single inductor can be achieved. This indicates that on the premise of maintaining the same output current volatility, compared with two independent inductors and a two - inductor - coupled structure, the three - inductor - coupled integrated structure requires a smaller inductance value, which helps to reduce the volume and weight of the inductor and improve its power density.

[0081] Refer to Figure 8 , Figure 8 which is a schematic diagram of the traditional two - phase interleaved parallel Boost circuit provided by the present invention, where U in is the input voltage, C 1 is the input - end support capacitor, L 1 and L 2 are the self - inductances of the inductors, i 1 and i 2 are the inductor currents, S 1 and S 2 are the switching devices, D 1 and D 2 are the free - wheeling diodes, C 2 is the output - point support capacitor, R is the load resistor, i O is the output current, iC is the current of the output terminal support capacitor.

[0082] Reference Figure 9 , Figure 9 , as shown in the schematic diagram of the two-phase interleaved parallel Boost circuit applying three coupled inductors provided by the present invention, where U in is the input voltage, C 1 is the input terminal support capacitor, S 1 and S 2 are switching devices, D 1 and D 2 are freewheeling diodes, C 2 is the output point support capacitor, R is the load resistor, i O is the output current, i C is the current of the output terminal support capacitor; the three-inductor coupled integration structure includes: the first coupled inductor L 1, the second coupled inductor L 2, and the third coupled inductor L 3. The mutual inductance between the first coupled inductor and the second coupled inductor is M 12 ; the mutual inductance between the first coupled inductor and the third coupled inductor is M 13 ; the mutual inductance between the second coupled inductor and the third coupled inductor is M 23 , where i 1 represents the inductor current of the first coupled inductor L 1, i 2 represents the inductor current of the second coupled inductor L 2, i L represents the synthesized inductor current.

[0083] Through the above embodiments of the present invention, three additional variables are introduced into the two-phase interleaved parallel circuit, namely L 3 、M 12 and M 23 , which improves the system design freedom and can achieve the goals of reducing both the single inductor current and the total current, reducing EMI, and increasing the power density. The planar coupled inductor has a compact structure, a simple magnetic core structure, low design, processing, and manufacturing costs, and is easy to maintain the parameter consistency between inductors.

[0084] In some embodiments, the coil uses traditional round wires. According to the actual application scenario, Litz wires, PCB coils, etc. can also be used. The shapes of the coil and the magnetic core are not limited to rectangles and can be circular or polygonal according to needs.

[0085] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the above technical solution, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A three-inductor coupling integrated structure, characterized in that, Including: A first coupled inductor, a second coupled inductor, and a third coupled inductor. The first coupled inductor, the second coupled inductor, and the third coupled inductor are arranged in an upper and lower stacked manner, adopting a spiral coil structure, and the spiral winding direction of the spiral coil structure is set based on the mutual inductance direction matching. Three sets of mutual inductance relationships are respectively formed by magnetic coupling between the first coupled inductor, the second coupled inductor, and the third coupled inductor, including: the mutual inductance between the first coupled inductor and the second coupled inductor, the mutual inductance between the first coupled inductor and the third coupled inductor, and the mutual inductance between the second coupled inductor and the third coupled inductor. Among them, the three sets of mutual inductance relationships and the self-inductance of the first coupled inductor, the self-inductance of the second coupled inductor, and the self-inductance of the third coupled inductor satisfy a preset constraint relationship to improve the power density.

2. The three-inductor coupled integrated structure according to claim 1, characterized in that The first coupled inductor, the second coupled inductor, and the third coupled inductor have the same coupled inductor structure. The coupled inductor structure from top to bottom is: a first back core, a multi-layer multi-turn planar coil, and a second back core.

3. The three-inductor coupled integrated structure according to claim 2, wherein The coupled inductor structure further includes: A first side core located below the first back core and a second side core located above the second back core. A first central core and a second central core, where the first central core is arranged closely adjacent to the first back core, and the second central core is arranged closely adjacent to the second back core. The first central core and the second central core are in close contact or at a preset distance.

4. The three-inductor coupled integrated structure according to claim 2, characterized in that, The multi-layer multi-turn planar coil includes: a first inductor coil, a second inductor coil, and a third inductor coil.

5. The three-inductor coupled integrated structure according to claim 4, wherein The winding direction of the multi-layer multi-turn planar coil is clockwise or counterclockwise; the winding direction is used to adjust the mutual inductance polarity between the first inductor coil, the second inductor coil, and the third inductor coil.

6. The three-inductor coupled integrated structure according to claim 1, wherein The three-inductor coupled integrated structure is applied to a two-phase interleaved parallel circuit, and the two-phase interleaved parallel circuit at least includes: a two-phase interleaved parallel Buck circuit and a two-phase interleaved parallel Boost circuit.

7. The three-inductor coupled integrated structure according to claim 6, wherein The terminal voltage of the first coupled inductor is: The terminal voltage of the second coupled inductor is: The terminal voltage of the third coupled inductor is: Among them, represents the terminal voltage of the first coupled inductor, represents the terminal voltage of the second coupled inductor, represents the terminal voltage of the third coupled inductor, represents the self-inductance of the first coupled inductor, represents the self-inductance of the second coupled inductor, represents the self-inductance of the third coupled inductor, represents the mutual inductance between the first coupled inductor and the third coupled inductor, represents the mutual inductance between the first coupled inductor and the second coupled inductor, represents the mutual inductance between the second coupled inductor and the third coupled inductor, represents the inductor current of the first coupled inductor, represents the inductor current of the second coupled inductor, represents time.

8. The three-inductor coupled integrated structure according to claim 1, wherein When the same-named terminals of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are the same.

9. The three-inductor coupled integrated structure according to claim 1, wherein When the different-named terminals of the first coupled inductor and the second coupled inductor are coupled, the signs of the mutual inductance between the first coupled inductor and the second coupled inductor and the mutual inductance between the second coupled inductor and the third coupled inductor are opposite.

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