A Multiphase Parallel Resonant Converter with Automatic Current Sharing Based on a Fully Coupled Inductor

Abstract

The present invention provides a multiphase parallel resonant converter with automatic current sharing based on a fully coupled inductor. An additional inductor is serially connected in each phase resonant unit, and the series inductors of each phase are integrally magnetically coupled in a full-coupling manner. To achieve the full-coupling integration, the winding wires of the series inductors of each phase are evenly wound together and jointly wound on the same iron core magnetic column of the fully coupled inductor. The beneficial effects of the present invention are as follows: automatic equalization of the branch currents of the multiphase parallel resonant converter is realized, so that the power distribution of each branch is equal. It is used for high-power parallel switching power supplies in occasions such as electric vehicles, hybrid vehicles, uninterruptible power supplies, power quality regulating power supplies, aviation power supplies, new energy power generation, and superconducting energy storage, etc., and has the advantages of low loss, high efficiency, avoiding local overheating of switching tubes or rectifier diodes, or excessive device voltage and current stresses, etc.

Description

Technical Field

[0001] This patent relates to a multi-phase parallel power electronic converter with automatic current sharing based on a fully coupled inductor, which can achieve automatic current sharing among parallel branches. Background Art

[0002] In recent years, switching power supplies that provide electrical energy for various electrical devices are developing towards low voltage, large current, small size, light weight, high efficiency, thinness, and integration. This includes voltage regulation modules that provide precision power for high-precision and high-speed microprocessors such as the central processing unit (CPU) and digital signal processor (DSP) of a computer, as well as switching power supplies that have emerged in recent years and are widely used in electric vehicles, hybrid vehicles, uninterruptible power supplies, power quality regulating power supplies, aviation power supplies, new energy power generation, superconducting energy storage, and other applications. These switching power supplies adopt the circuit topology of resonant converters, enabling the switching transistors to achieve zero-voltage turn-on and zero-current turn-off within the full load range, thereby reducing losses and improving efficiency. To achieve high-power applications of resonant converters, people often use a two-phase or multi-phase parallel resonant converter circuit topology. However, due to inconsistent parameters of the resonant capacitors or resonant inductors in each parallel branch of the resonant converter, the currents in each branch are not equal, and the power distribution in each branch is not equal, leading to serious problems such as local overheating of switching transistors or rectifier diodes, or excessive voltage and current stress on devices. Summary of the Invention

[0003] Aiming at the defects of the prior art, this patent provides a multi-phase parallel resonant converter with automatic current sharing based on a fully coupled inductor, which has the advantages of simple structure, low loss, high efficiency, and can achieve automatic current sharing among parallel branches.

[0004] The technical solution adopted by this patent to solve its technical problems is as follows:

[0005] A multi-phase parallel resonant converter with automatic current sharing based on a fully coupled inductor, comprising:

[0006] The first-phase resonant converter Phase1, including the first switching circuit S1, the first resonant capacitor C r1 , the first resonant inductor L r1 , the first resonant transformer T1, the first equivalent exciting inductor L P1 connected in parallel at both ends a and b of the primary winding N m1 of the first resonant transformer T1, and the first rectifier circuit R1; the first resonant capacitor C r1 , the first resonant inductor L r1is connected in series with the primary winding of the first resonant transformer T1 to form a first resonant unit; the first switch circuit S1 has an input port 1-1 and an output port 1-2, and the first rectifier circuit R1 has an input port 1-3 and an output port 1-4;

[0007] The second-phase resonant converter Phase2 includes a second switch circuit S2, a second resonant capacitor C r2 , a second resonant inductor L r2 , a second resonant transformer T2, and a second equivalent exciting inductor L p2 connected in parallel across the two ends e, f of the primary winding N m2 of the second resonant transformer T2; the second rectifier circuit R2; the second resonant capacitor C r2 , the second resonant inductor L r2 and the primary winding of the second resonant transformer T2 are connected in series to form a second resonant unit; the second switch circuit S2 has an input port 2-1 and an output port 2-2, and the second rectifier circuit R2 has an input port 2-3 and an output port 2-4;

[0008] It is characterized in that: an inductor L1 is connected in series between the output port 1-2 of the first switch circuit S1 and the first resonant unit, and an inductor L2 is connected in series between the output port 2-2 of the second switch circuit S2 and the second resonant unit. The inductors L1 and L2 are fully coupled in the forward direction of the magnetic field to form a forward full-coupling inductor L 12 , and the coupling coefficient k of the full-coupling inductor L 12 is close to 1; a multi-phase parallel LLC resonant converter capable of automatically equalizing current based on a forward full-coupling inductor is formed; by adjusting the conduction phase sequence of the first switch circuit S1 and the second switch circuit S2, the phase difference between the current f1 flowing through the first inductor L1 and the current i2 flowing through the second inductor L2 is 180°; in order to implement the forward full-coupling inductor L 12 , the winding wires of the inductor L1 and the winding wires of the inductor L2 are uniformly wound around each other in a Litz wire structure and are jointly wound on the same iron core magnetic column of the full-coupling inductor L 12 to ensure that the inductance values of the inductor L1 and the inductor L2 are equal, and the directions of the winding current i1 flowing through the inductor L1 and the winding current i2 flowing through the inductor L2 are the same.

[0009] The beneficial effects of this patent are as follows: This patent provides a multi-phase parallel resonant converter with automatic current sharing based on a fully coupled inductor. By introducing a fully coupled inductor into the traditional multi-phase parallel resonant converter, since the leakage inductance of the fully coupled inductor is very small, close to zero, the fully coupled inductor basically does not participate in the resonance process of the multi-phase parallel resonant converter, does not affect the analysis of the working principle of the multi-phase parallel resonant converter and the design of resonance parameters, and does not require the addition of complex control methods, and has a good current sharing effect; the magnetic flux of the introduced fully coupled inductor is low, and the core loss is small, and the multi-phase parallel resonant converter based on the fully coupled inductor has higher efficiency; applying this technology to high-power switching power supplies has the advantages of low loss, high efficiency, avoiding local overheating of switching tubes or rectifier diodes, or excessive device voltage and current stress.

[0010] The following takes examples in conjunction with the drawings for specific illustration. Brief Description of the Drawings

[0011] To illustrate the embodiments more clearly, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this patent. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 It is the circuit topology diagram of a multi-phase parallel LLC resonant converter with automatic current sharing based on a forward fully coupled inductor provided by Embodiment 1 of this patent.

[0013] Figure 2 It is the circuit topology diagram of a multi-phase parallel LLC resonant converter with automatic current sharing based on a reverse fully coupled inductor provided by Embodiment 2 of this patent.

[0014] Figure 3 It is the circuit topology diagram of a multi-phase parallel LCC resonant converter with automatic current sharing based on a forward fully coupled inductor provided by Embodiment 3 of this patent.

[0015] Figure 4 is Figure 1 a forward fully coupled inductor L 12 an embodiment of.

[0016] Figure 5 is Figure 2 a reverse fully coupled inductor L 12 an embodiment of.

[0017] Figure 6 It is the simulation waveform of the unbalanced resonant currents of two phases of a traditional two-phase resonant converter under two-phase asymmetric resonant parameters.

[0018] Figure 7 Under two-phase asymmetric resonance parameters, Figure 1 The two-phase resonance converter adopts Figure 4 The simulation waveform of the resonance current with equal current sharing in both phases of the fully coupled inductor.

[0019] Figure 8 , 9 Is at Figure 6 Under the two-phase asymmetric resonance parameters, the simulation waveform of the output current with unequal current sharing in both phases of the traditional two-phase resonance converter.

[0020] Figure 10 , 11 Is at Figure 6 Under the two-phase asymmetric resonance parameters, Figure 1 The two-phase resonance converter adopts Figure 4 The simulation waveform of the output current with equal current sharing in both phases of the fully coupled inductor.

[0021] Figure 12 Is at Figure 6 Under the two-phase asymmetric resonance parameters, Figure 1 The two-phase resonance converter adopts Figure 4 The experimental waveform of the resonance current with equal current sharing in both phases of the fully coupled inductor.

[0022] In the figure, V in - Input voltage, V o - Output voltage; Phase1 - The first branch of the multi-phase parallel resonance converter; S1 - The first switch circuit; C r1 - The first resonance capacitor, L r1 - The first resonance inductor, T1 - The first resonance transformer; N P1 - The primary winding of the first resonance transformer T1, N S1 - The secondary winding of the first resonance transformer T1, L m1 - The equivalent exciting inductor connected in parallel at both ends a, b of the primary winding N P1 ; R1 - The first rectifier circuit; 1-1 - The input port of the first switch circuit S1, 1-2 - The output port of the first switch circuit S1, 1-3 - The input port of the first rectifier circuit R1, 1-4 - The output port of the first rectifier circuit R1; C P1 - The first parallel resonance capacitor; i1 - The resonance current of the first branch, i rect1 - The output current of the first branch;

[0023] Phase2 - The second branch of the multi-phase parallel resonance converter; S2 - The second switch circuit; C r2 - The second resonance capacitor, L r2 - The second resonance inductor, T2 - The second resonance transformer; N P2- The primary winding of the second resonant transformer T2, N S2 - The secondary winding of the second resonant transformer T2, L m2 - The equivalent exciting inductance connected in parallel across the two ends g and h of the primary winding N P2 ; R2 - The second rectifying circuit; 2-1 - The input port of the second switching circuit S2, 2-2 - The output port of the second switching circuit S2, 2-3 - The input port of the second rectifying circuit R2, 2-4 - The output port of the second rectifying circuit R2; C P2 - The second parallel resonant capacitor; i2 - The resonant current of the second branch, i rect2 - The output current of the second branch;

[0024] L 12 - The fully coupled inductor; L1 - The self-inductance of the first branch of the fully coupled inductor L 12 ; L2 - The self-inductance of the second branch of the fully coupled inductor L 12 ; M - The mutual inductance between the first branch and the second branch of the fully coupled inductor L 12 ; Detailed implementation manners

[0025] The core idea of this patent is as follows: Another inductor is connected in series in each phase resonant unit of the multiphase parallel resonant converter, and the series inductors of each phase are integrally coupled magnetically; To achieve the full coupling integration, the winding wires of the series inductors of each phase are wound around each other evenly in a Litz wire structure and are jointly wound on the same iron core column of the fully coupled inductor; If the conduction phase sequence of the switching circuits S1 and S2 is adjusted so that the current phases flowing through the series inductor windings of each phase are opposite, then the currents of the inductor windings of each phase should flow in from the same end of the winding wire to achieve the forward full coupling of each phase inductor and realize the automatic balance of the branch currents of the multiphase parallel resonant converter; If the conduction phase sequence of the switching circuits S1 and S2 is adjusted so that the current phases flowing through the series inductor windings of each phase are the same, then the currents of the inductor windings of each phase flow in from the opposite ends of the winding wire to achieve the reverse full coupling of each phase inductor and realize the automatic balance of the branch currents of the multiphase parallel resonant converter.

[0026] Next, in combination with the drawings in the embodiments of this patent, the technical solutions in the embodiments of this patent will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of this patent, rather than all of the embodiments. Based on the core idea and embodiments of this patent, other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of this patent.

[0027] In order to comprehensively understand this patent, many specific details are mentioned in the following detailed description, but those skilled in the art should understand that this patent can be implemented without these specific details.

[0028] Embodiment 1:

[0029] Refer to the attached Figure 1 , a multiphase parallel resonant converter with automatic current sharing based on a fully coupled inductor, comprising:

[0030] The first-phase resonant converter Phase1 includes a first switching circuit S1, a first resonant capacitor C r1 , a first resonant inductor L r1 , a first resonant transformer T1, and a first equivalent exciting inductor L P1 connected in parallel across the two ends a and b of the primary winding N m1 of the first resonant transformer T1, and a first rectifier circuit R1; the first resonant capacitor C r1 , the first resonant inductor L r1 and the primary winding of the first resonant transformer T1 are connected in series to form a first resonant unit; the first switching circuit S1 has an input port 1-1 and an output port 1-2, and the first rectifier circuit R1 has an input port 1-3 and an output port 1-4;

[0031] The second-phase resonant converter Phase2 includes a second switching circuit S2, a second resonant capacitor C r2 , a second resonant inductor L r2 , a second resonant transformer T2, and a second equivalent exciting inductor L P2 connected in parallel across the two ends e and f of the primary winding N m2 of the second resonant transformer T2, and a second rectifier circuit R2; the second resonant capacitor C r2 , the second resonant inductor L r2 and the primary winding of the second resonant transformer T2 are connected in series to form a second resonant unit; the second switching circuit S2 has an input port 2-1 and an output port 2-2, and the second rectifier circuit R2 has an input port 2-3 and an output port 2-4;

[0032] An inductor L1 is connected in series between the output port 1-2 of the first switching circuit S1 and the first resonant unit, and an inductor L2 is connected in series between the output port 2-2 of the second switching circuit S2 and the second resonant unit. The inductors L1 and L2 are fully coupled magnetically in the forward direction to form a forward fully coupled inductor L 12 , and the coupling coefficient k of the fully coupled inductor L 12 is close to 1; a multiphase parallel LLC resonant converter with automatic current sharing based on a forward fully coupled inductor is formed;

[0033] By adjusting the conduction phase sequence of the first switch circuit S1 and the second switch circuit S2, the phases of the current i1 flowing through the first inductor L1 and the current i2 flowing through the second inductor L2 are 180° different from each other;

[0034] Refer to the attached Figure 4 , in order to implement the forward fully coupled inductor L 12 The winding wire of the inductor L1 and the winding wire of the inductor L2 are evenly wound together using a Litz wire structure and are wound together on the fully coupled inductor L 12 On the same iron core magnetic column, it is ensured that the inductance values ​​of the inductor L1 and the inductor L2 are equal, and the directions of the winding current i1 flowing through the inductor L1 and the winding current i2 flowing through the inductor L2 are the same.

[0035] The implementation effect of this embodiment is shown in the attached Figure 6 - 12 .

[0036] Attached Figure 1 The fully coupled inductor in the Figure 4 The structure, attached Figure 4 The fully coupled inductor in the embodiment adopts the inductance parameters described in Table 1; as described in Table 2, when the conventional two-phase resonant converter (in the attached Figure 1 Remove the fully coupled inductor L 12 ) and attached Figure 1 When the resonance parameters of the two-phase resonant units of the two-phase resonant converter are asymmetric, Figure 6 It can be seen that the simulated waveforms of the two-phase resonant currents i1 and i2 of the traditional two-phase resonant converter are very different and very unbalanced; Figure 7 It can be seen that the two-phase resonant converter (see Appendix) proposed in this embodiment Figure 1 ) and its fully coupled inductor (attached Figure 4 ), the simulation waveforms of the two-phase resonant current i1 and i2 are very different and very balanced. As can be seen from Table 3, the current sharing error of the two-phase resonant current of the traditional two-phase resonant converter reaches 43.99%; while the current sharing error of the two-phase resonant current of the two-phase resonant converter proposed in this embodiment is only 0.68%.

[0037] Table 1 Inductance parameters

[0038] Parameter <![CDATA[Coupled inductor L1]]> <![CDATA[Coupled Inductor L2]]> Self - inductance value 19.54 uH 19.54 uH Leakage inductance value 0.2 uH 0.2 uH Coupling coefficient k 0.9898 0.9898

[0039] Table 2 Two-phase resonance parameter asymmetry

[0040]

[0041] Table 3 Current sharing error of two-phase resonant current

[0042]

[0043] As shown in Appendix Figure 8 、 9 It can be seen that the simulation waveforms of the two-phase output currents i rec1 、i rec2 of the traditional two-phase resonant converter are very different and extremely unbalanced; as shown in Appendix Figure 10 、 11 It can be seen that for the two-phase resonant converter (Appendix Figure 1 ) and its fully coupled inductor (Appendix Figure 4 ) proposed in this embodiment, the simulation waveforms of the two-phase output currents i rec1 、i rec2 have very little difference and are extremely balanced. As can be seen from Table 4, the current sharing error of the two-phase output currents of the traditional two-phase resonant converter reaches 44.56%; while the current sharing error of the two-phase output currents of the two-phase resonant converter proposed in this embodiment is only 0.87%.

[0044] Table 4 Current Sharing Error of Two-Phase Output Currents

[0045]

[0046] The implementation effect of this embodiment is verified above through circuit simulation (Appendix Figure 6 - 11 ).

[0047] As shown in Appendix Figure 12 It can be seen that the experimental waveforms of the two-phase resonant currents i1 and i2 of the two-phase resonant converter proposed in this embodiment have very little difference and are extremely balanced.

[0048] The implementation effect of this embodiment is verified above through experiments (Appendix Figure 12 ).

[0049] Embodiment 2:

[0050] Referring to Appendix Figure 2 , a multiphase parallel resonant converter with automatic current sharing based on a fully coupled inductor, by adjusting the conduction phase sequence of the first switch circuit S1 and the second switch circuit S2 in Appendix Figure 1 , making the phases of the current i1 flowing through the first inductor L1 and the current i2 flowing through the second inductor L2 the same; changing the forward fully coupled inductor L Figure 1 in Appendix 12 to a reverse fully coupled inductor L 12 ;

[0051] Referring to Appendix Figure 5 , in order to implement the reverse fully coupled inductor L 12 described in Appendix Figure 2 , by using the Appendix Figure 1The input end and the output end of the winding wire of the inductor L2 are swapped, so that the direction of the winding current i2 flowing through the inductor L2 is opposite to the direction of the winding current i1 flowing through the inductor L1.

[0052] Embodiment 3:

[0053] Refer to the appendix Figure 3 , a multi-phase parallel resonant converter based on a fully coupled inductor that can automatically equalize current. Replace the first equivalent magnetizing inductance L Figure 1 in the appendix m1 with the first parallel resonant capacitor C P1 , and replace the second equivalent magnetizing inductance L Figure 1 in the appendix m2 with the second parallel resonant capacitor C P2 to form a multi-phase parallel LCC resonant converter based on a fully coupled inductor that can automatically equalize current.

[0054] The above-described embodiments are only preferred embodiments of this patent and are not used to limit the protection scope of this patent. The principles and implementation manners of this patent are described in the above multiple embodiments, which are only used to help understand the method and core idea of this patent; at the same time, for those of ordinary skill in the art, according to the idea of this patent, there will be changes in the specific implementation manners and application scopes. Therefore, the content of this specification should not be construed as a limitation of this patent. Any modifications, equivalent replacements, and improvements made within the spirit and principle of this patent are all included within the protection scope of this patent.

Claims

1. A multiphase parallel resonant converter with automatic current sharing based on a fully coupled inductor, comprising: The first-phase resonant converter Phase1 includes a first switching circuit S1 and a first resonant capacitor C r1 , a first resonant inductor L r1 , a first resonant transformer T1, and a first equivalent exciting inductor L P1 connected in parallel across the two ends a and b of the primary winding N m1 of the first resonant transformer T1; the first rectifier circuit R1; the first resonant capacitor C r1 , the first resonant inductor L r1 and the primary winding of the first resonant transformer T1 are connected in series to form a first resonant unit; the first switching circuit S1 has an input port 1-1 and an output port 1-2, and the first rectifier circuit R1 has an input port 1-3 and an output port 1-4; The second-phase resonant converter Phase2 includes a second switching circuit S2 and a second resonant capacitor C r2 , a second resonant inductor L r2 , a second resonant transformer T2, and a second equivalent exciting inductor L P2 connected in parallel across the two ends e and f of the primary winding N m2 of the second resonant transformer T2; the second resonant capacitor C r2 , the second resonant inductor L r2 and the primary winding of the second resonant transformer T2 are connected in series to form a second resonant unit; the second switching circuit S2 has an input port 2-1 and an output port 2-2, and the second rectifying circuit R2 has an input port 2-3 and an output port 2-4; Characterized in that: An inductor L1 is connected in series between the output port 1-2 of the first switching circuit S1 and the first resonant unit, and an inductor L2 is connected in series between the output port 2-2 of the second switching circuit S2 and the second resonant unit. The inductors L1 and L2 are fully coupled magnetically in the forward direction to form a forward fully coupled inductor L 12 , the fully coupled inductor L 12 has a mutual inductance of M, and the fully coupled inductor L 12 has a coupling coefficient close to 1; A multiphase parallel LLC resonant converter with automatic current sharing based on a forward fully coupled inductor is formed; By adjusting the conduction phase sequence of the first switch circuit S1 and the second switch circuit S2, the direction of the current i1 flowing through the inductor L1 and the direction of the current i2 flowing through the inductor L2 are opposite; To implement the forward fully-coupled inductor L 12 , the winding wires of the inductors L1 and L2 are evenly wound around each other and jointly wound on the same iron core magnetic column of the fully-coupled inductor L 12 , ensuring that the inductance values of the inductor L1 and the inductor L2 are equal, and the directions of the winding current i1 flowing through the inductor L1 and the winding current i2 flowing through the inductor L2 are the same.

2. The multi-phase parallel resonant converter capable of automatically equalizing current based on a fully-coupled inductor according to claim 1, wherein: By adjusting the conduction phase sequence of the first switching circuit S1 and the second switching circuit S2, the phases of the current i1 flowing through the first inductor L1 and the current i2 flowing through the second inductor L2 are made the same; by swapping the input end and the output end of the winding wire of the inductor L2, the direction of the current i2 flowing through the inductor L2 is made opposite to the direction of the current i1 flowing through the inductor L1, forming a reverse fully coupled inductor L 12 , the reverse fully coupled inductor L 12 has a coupling coefficient k close to -1.

3. A multi-phase parallel resonant converter capable of automatically equalizing current based on a fully coupled inductor according to claim 1 or 2, characterized in that: Replace the first exciting inductance L of the first resonant transformer T1 m1 with the first parallel resonant capacitor C P1 , and replace the second exciting inductance L of the second resonant transformer T2 m2 with the second parallel resonant capacitor C P2 , to form a multi-phase parallel LCC resonant converter based on a fully coupled inductor with automatic current sharing capability.

4. A multiphase parallel resonant converter capable of automatic current sharing based on a fully coupled inductor according to claim 1 or 2, characterized in that: The number of parallel phases of the converter and its fully coupled inductor are extended to three phases or more.

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