Current Sharing Method and Device for Multi-Phase Interleaved Parallel LLC Resonant Converter

Abstract

In order to effectively solve the problem that there is a large deviation in the voltage gain between the parallel phases of a multi-phase interleaved LLC resonant converter, resulting in different magnitudes of load currents output by each phase of the resonant converter, and the problem that a fault in a certain phase in the prior art will cause the entire machine to shut down due to a fault, the present invention proposes a novel current sharing method and implementation device for a multi-phase interleaved LLC resonant converter. The steps are as follows: Step 1: An N-phase parallel LLC resonant converter is formed by N half-bridge LLC resonant converters with the same rated parameters in an input parallel and output parallel manner, where N is an integer greater than or equal to 2; Step 2: Generate N - 1 phase-controllable AC current sources and inject them into the resonant capacitors of N - 1 phases of the LLC resonant converter respectively; Step 3: Adjust the phases of the injected AC current sources respectively according to the output current deviation of each phase of the LLC resonant converter, so as to achieve current sharing of the output currents of each phase of the LLC resonant converter.

Description

Technical Field

[0001] The present invention belongs to the switching power supply technology in the field of power electronics, and relates to a current sharing method and an implementation device for a novel multi-phase interleaved parallel LLC resonant converter. Background Art

[0002] LLC resonant converters have been widely used in applications with high requirements for converter efficiency and power density due to their advantages such as high efficiency, low EMI, and high power density. In applications with high power and large current, converters are required to have larger capacity, higher power density, and lower losses. Obviously, single-phase LLC resonant converters can no longer meet the requirements. Therefore, multi-phase interleaved parallel LLC resonant converters are usually adopted to reduce the output current ripple and increase the output power.

[0003] However, since the voltage gain of LLC resonant converters is closely related to the parameters of resonant devices, in a multi-phase parallel system in practical applications, due to problems such as manufacturing process deviations and parameter changes caused by environmental variations, there will inevitably be differences in each resonant element, which will in turn lead to large deviations in the voltage gain between each parallel phase, resulting in different magnitudes of load currents output by each phase of the resonant converter. This will seriously affect the efficiency, reliability, and service life of the entire system.

[0004] Regarding the problem of uneven current sharing in multi-channel converters, an existing technology provides an idea of changing the parameters of resonant devices in the resonant cavity, such as Figure 1 shown. That is, by introducing a variable inductor into the resonant circuit to equivalently change the energy in the resonant cavity, the goal of making the voltage gains of each phase of the resonant converter equal in real time is achieved, thereby ensuring that the load currents are equal in real time. Similarly, starting from this idea, a structure of a two-phase interleaved parallel LLC resonant converter with a switched capacitor introduced is given, such as Figure 2 shown. By introducing a switched capacitor, the energy in the resonant cavity can be easily changed, and finally the goal of current sharing in each phase is achieved. However, the introduced switched capacitor has complex control, and the volume and cost of the system will increase, which is not conducive to improving the power density and efficiency of the system.

[0005] Another existing technology proposes a method for automatically equalizing the current between each phase by connecting the secondary windings of the transformer in groups, such as Figure 3 shown. This method can achieve automatic current sharing without adding additional control strategies or additional circuit components. However, due to the series connection of the secondary windings of the transformer in the topological structure of the transformer secondary group connection, when a fault occurs in one of the phases, the entire machine will fail and stop. Therefore, for practical applications, its reliability needs to be improved.

[0006] Analysis shows that although the above two methods can solve the current sharing problem of the multiphase resonant converter, they will introduce new problems such as complex control methods, increased costs, and poor reliability. In order to effectively solve the uneven current sharing problem of each phase of the multiphase interleaved LLC resonant converter, and at the same time improve the conversion efficiency and reliability of the entire system, it is a very practical and challenging task to propose an effective solution for the current sharing problem of the multiphase LLC resonant converter. Summary of the Invention

[0007] In view of the deficiencies of the existing current sharing technologies, the present invention proposes a novel current sharing method and implementation device for a multiphase interleaved LLC resonant converter.

[0008] The steps of the current sharing method for the multiphase interleaved LLC resonant converter of the present invention are as follows:

[0009] Step 1: An N-phase parallel LLC resonant converter is formed by N half-bridge LLC resonant converters with the same rated parameters in an input parallel and output parallel manner, where N is an integer greater than or equal to 2;

[0010] Step 2: Generate N - 1 phase-controllable AC current sources and inject them into the resonant capacitors of N - 1 phase LLC resonant converters respectively;

[0011] Step 3: Adjust the phases of the injected AC current sources respectively according to the output current deviations of each phase LLC resonant converter fed back, so as to achieve current sharing of the output currents of each phase LLC resonant converter.

[0012] The present invention provides a novel multiphase interleaved LLC resonant converter device.

[0013] The multiphase interleaved LLC resonant converter device of the present invention includes:

[0014] A multiphase interleaved LLC resonant converter composed of N half-bridge LLC resonant converter modules, N - 1 auxiliary current sharing branches composed of auxiliary switch arms, auxiliary inductors and auxiliary capacitors, and a controller, where N is an integer greater than or equal to 2.

[0015] Among them, the first-phase half-bridge LLC resonant converter is a conventional half-bridge LLC resonant converter. The first end of the resonant capacitor in the i-phase module half-bridge LLC resonant converter is connected to the source of the lower tube of the primary switch arm of this phase converter, and its second end is connected to the opposite end of the primary winding of the transformer of this phase converter;

[0016] The auxiliary switch arm of the i-th phase auxiliary current sharing branch includes an upper switch and a lower switch. The drain of the upper switch is connected to the positive pole of the input source, the source of the upper switch is connected to the drain of the lower switch to form the midpoint of the auxiliary switch arm and is connected to one end of the auxiliary capacitor. The other end of the auxiliary capacitor is connected to one end of the auxiliary inductor. The other end of the auxiliary inductor is connected to the second end of the resonant capacitor in the i-th phase module half-bridge LLC resonant converter. The source of the lower switch is connected to the primary ground;

[0017] where, i = 2, 3…N.

[0018] Preferably, the controller synchronously controls the driving signals V o_FB or the total output current feedback signal I o_FB , through the internal voltage loop or current loop, of the switching tubes Q j1 ~Q j2 of each phase module, so that the output voltage or the total output current of the converter is constant, and a fixed phase shift angle is formed between each phase module to obtain the optimal ripple cancellation effect; where, the control signals V Gj1 ~V Gj2 are all square wave signals that are pairwise complementary with a duty cycle close to 50% and with a dead time left. Gj1 ~V Gj2

[0019] Furthermore, the controller adjusts the phase difference between the driving signals of the auxiliary switch arm of the i-th phase auxiliary current sharing branch and the primary switch arm of the i-th phase module by detecting the deviation between the output current feedback signals of each phase module, so as to achieve current sharing of the output currents of each phase module.

[0020] Preferably, the half-bridge LLC resonant converter includes a switch arm composed of a switching tube Q 11 and a switching tube Q 12 , a resonant capacitor C r1 , a resonant inductor L r1 , a transformer T1, a rectifying tube Q 13 , a rectifying tube Q 14 and an output capacitor C o1 ;

[0021] The drain of the switching tube Q 11 is connected to the positive terminal of the input voltage source V in , its source is connected to the same-name terminal of the transformer T1, the different-name terminal of the transformer T1 is connected to one end of the resonant inductor L r1 , the other end of the resonant inductor L r1 is connected to one end of the resonant capacitor C r1 ; The drain of the switching tube Q 12 is connected to the switching tube Q 11 ​is connected to the source electrode, and its source electrode is connected to the primary side ground and the resonant capacitor C r1 The other end;

[0022] The same-named end of the first secondary winding of the transformer T1 is connected to the source electrode of the rectifying diode Q 13 The source electrode of, the rectifying diode Q 13 The drain electrode is connected to the positive terminal of the output capacitor C o1 The same-named end of the second secondary winding of the transformer T1 is connected to the opposite-named end of the first secondary winding of the transformer T1 and the negative terminal of the output capacitor C o1 The opposite-named end of the second secondary winding of the transformer T1 is connected to the source electrode of the rectifying diode Q 14 The source electrode of, the rectifying diode Q 14 The drain electrode is connected to the positive terminal of the output capacitor C o1 The positive terminal.

[0023] Specifically, the basic principle of the present invention is: when there is a situation where the resonant parameters in the N-phase interleaved parallel LLC resonant converter are inconsistent, by injecting an externally adjustable-phase current into the resonant capacitors of the N-1 phase resonant converters through N-1 auxiliary current-sharing branches respectively, by changing the phase between the original resonant current and the injected external current, equivalently changing the magnitude of the resonant current in the converter, thereby eliminating the current-sharing error caused by the deviation of the resonant element parameters between different phases, and realizing output current sharing of the multi-phase interleaved parallel LLC resonant converter.

[0024] Preferably, the implementation device obtained according to the current-sharing method of the multi-phase interleaved parallel LLC resonant converter proposed by the present invention further includes a phase-shifted control multi-phase interleaved parallel LLC resonant converter.

[0025] A phase-shifted control multi-phase interleaved parallel LLC resonant converter includes: a multi-phase interleaved parallel LLC resonant converter composed of N half-bridge LLC resonant converter modules, N-1 phase-shifting inductance modules composed of an auxiliary inductor L ai and an auxiliary capacitor C ai connected in series, and a controller, where N is an integer greater than or equal to 2, and a phase-controllable AC current source is output through the phase-shifting inductance module.

[0026] Wherein, the resonant capacitor C in the i-th phase half-bridge LLC resonant converter module ri The first end is connected to the source electrode of the lower tube of the primary side switch bridge arm of the i-th phase half-bridge LLC resonant converter module, its second end is connected to one end of the i-th phase phase-shifting inductance module, and the other end of the i-th phase phase-shifting inductance module is connected to the midpoint of the primary side switch bridge arm of the (i-1)-th phase half-bridge LLC resonant converter module;

[0027] Wherein, i = 2, 3... N.

[0028] Preferably, the controller according to the feedback signal V collected o_FBOr I o_FB , synchronously control the switching frequency of the resonant converter through the internal voltage loop or current loop, and then adjust the output voltage or the total output current; adjust the phase difference of the driving signals of each phase resonant converter by detecting the deviation between the output current feedback signals of each phase LLC resonant converter, that is, the interleaving angle between each phase to change the phase of each AC current source, so as to achieve current sharing of the output currents of each phase LLC resonant converter.

[0029] The present invention also provides a wide-voltage-gain LLC resonant converter based on an auxiliary branch, including: a half-bridge LLC resonant converter and an auxiliary branch;

[0030] The half-bridge LLC resonant converter includes a switching bridge arm composed of a switching tube Q1 and a switching tube Q2, a resonant capacitor Cr, a resonant inductor Lr, a transformer T, a rectifying tube Q3, a rectifying tube Q4 and an output capacitor Co;

[0031] The drain of the switching tube Q1 is connected to the positive terminal of the input voltage source V in , its source is connected to the same-name terminal of the transformer T, the different-name terminal of the transformer T is connected to one end of the resonant inductor L r , the other end of the resonant inductor L r is connected to one end of the resonant capacitor C r ; the drain of the switching tube Q2 is connected to the source of the switching tube Q1, and its source is connected to the primary ground and the other end of the resonant capacitor C r ;

[0032] The same-name terminal of the first secondary winding of the transformer T is connected to the source of the rectifying tube Q3, the drain of the rectifying tube Q3 is connected to the positive terminal of the output capacitor C o , the same-name terminal of the second secondary winding of the transformer T is connected to the different-name terminal of the first secondary winding of the transformer T and the negative terminal of the output capacitor C o , the different-name terminal of the second secondary winding of the transformer T is connected to the source of the rectifying tube Q4, and the drain of the rectifying tube Q4 is connected to the positive terminal of the output capacitor C o ;

[0033] The auxiliary branch includes an auxiliary bridge arm composed of an upper switching tube Q a1 and a lower switching tube Q a2 , the drain of Q a1 is connected to the positive pole of the input source, the source of Q a1 is connected to the drain of Q a2 to form the midpoint of the auxiliary switching bridge arm and connect one end of the auxiliary capacitor, the other end of the auxiliary capacitor C a is connected to one end of the auxiliary inductor L a , the other end of the auxiliary inductor La is connected to the second end of the resonant capacitor C r in the half-bridge LLC resonant converter; the source of Q a2 is connected to the primary ground.

[0034] Specifically, the basic principle of the present invention is as follows: When the resonance parameters in the N-phase interleaved parallel LLC resonant converter are inconsistent, by changing the phase of the injected alternating current, the magnitude of the resonant current in the injected LLC resonant converter is equivalently changed, thereby eliminating the current sharing error caused by the deviation of the resonance element parameters between different phases, and realizing current sharing at the output of the multi-phase interleaved parallel LLC resonant converter.

[0035] The beneficial effects of the present invention are as follows: The present invention generates N - 1 alternating current sources to inject alternating currents with controllable phases into the resonance capacitors of the N - 1 phase LLC resonant converters, changes the phase between the original resonant current and the injected alternating current, equivalently changes the magnitude of the resonant current and the voltage gain of the injected converter, thereby eliminating the current sharing error caused by the deviation of the resonance element parameters between different phases, and realizing current sharing at the output of the multi-phase interleaved parallel LLC resonant converter. There is a phase difference between each phase converter, which can achieve the effect of output current ripple cancellation, and the alternating current source circuit and the control circuit are easy to implement. Description of the Drawings

[0036] Figure 1 A single-phase LLC resonant converter based on variable inductance of the prior art;

[0037] Figure 2 A two-phase half-bridge LLC resonant converter based on switched capacitors of the prior art;

[0038] Figure 3 Another two-phase half-bridge LLC resonant converter based on the grouped connection of secondary windings of the prior art;

[0039] Figure 4 A flowchart of the method steps for current sharing of the multi-phase interleaved parallel LLC resonant converter of the present invention

[0040] Figure 5 A schematic diagram of the first specific embodiment of the implementation device of the multi-phase interleaved parallel LLC resonant converter of the present invention;

[0041] Figure 6 An AC equivalent circuit of the i-th phase module in the implementation device of the multi-phase interleaved parallel LLC resonant converter of the present invention;

[0042] Figure 7 A specific embodiment of the wide voltage gain LLC resonant converter of the present invention

[0043] Figure 8 A schematic diagram of the second specific embodiment of the implementation device of the multi-phase interleaved parallel LLC resonant converter of the present invention;

[0044] In the figure: 100 is an N-phase interleaved parallel resonant LLC resonant converter, 101 is a controller, 200 is an auxiliary branch, 300 is a half-bridge LLC resonant converter, and 1001 is a controller. Detailed implementation

[0045] Well-known implementation methods and operating means are not described in detail herein to avoid confusing the various technical implementation schemes of the present invention. However, for those skilled in the art, the lack of one or more specific details or components does not affect the understanding and implementation of the present invention.

[0046] Reference Figure 4 , the steps of the current sharing method for the multi-phase interleaved parallel LLC resonant converter of the present invention are as follows:

[0047] Step 1: An N-phase parallel LLC resonant converter is formed by N half-bridge LLC resonant converters with the same rated parameters in an input parallel and output parallel manner, where N is an integer greater than or equal to 2;

[0048] Step 2: Generate N - 1 phase-controllable AC current sources and inject them into the resonant capacitors of N - 1 phase LLC resonant converters respectively;

[0049] Step 3: Adjust the phases of the injected AC current sources respectively according to the output current deviations of each phase LLC resonant converter in feedback to achieve current sharing of the output currents of each phase LLC resonant converter.

[0050] According to the above current sharing method of the present invention, the first specific embodiment of the implementation device of the multi-phase interleaved parallel LLC resonant converter of the present invention can be obtained as Figure 5 shown, including: an N-phase interleaved parallel resonant LLC resonant converter 100 and a controller 101. By describing the specific embodiments of the present invention, the features and details of the present invention can be more easily understood. In the description of the present invention, let one switching period of the LLC resonant converter correspond to a 360-degree phase angle, and the phases of each phase LLC resonant converter are determined by the phases of the drive signals of their switching bridge arms.

[0051] The first phase module of the N-phase interleaved parallel resonant LLC resonant converter is a conventional half-bridge LLC resonant converter.

[0052] The half-bridge LLC resonant converter includes a switching bridge arm composed of a switching tube Q 11 and a switching tube Q 12 , a resonant capacitor C r1 , a resonant inductor L r1 , a transformer T1, a rectifier tube Q 13 , a rectifier tube Q 14 and an output capacitor C o1 .

[0053] Switching tube Q 11 The drain is connected to the input voltage source V in The positive terminal of the resonant inductor is connected to the source terminal of the resonant inductor L. r1 One end of the resonant inductor L r1 The other end of the switch is connected to the same terminal of transformer T1. 12 The drain and switch tube Q 11 The source of the capacitor is connected to the primary ground, and the resonant capacitor C r1 One end of the transformer is connected to the primary ground, and the other end is connected to the opposite end of the transformer T1. The same end of the first secondary winding of the transformer T1 is connected to the rectifier tube Q 13 The drain of the rectifier tube Q 13 The source is connected to the output capacitor C o1 The negative end of the transformer T1's second secondary winding is connected to the opposite end of the transformer T1's first secondary winding and the output capacitor C o1 The positive terminal of the transformer T1's second secondary winding is connected to the rectifier tube Q 14 The drain of the rectifier tube Q 14 The source is connected to the output capacitor C o1 negative terminal.

[0054] The second to N-th phase modules of the N-phase interleaved parallel resonant LLC resonant converter include auxiliary current sharing branches 10i and conventional half-bridge LLC resonant converters, where i=2, 3...N.

[0055] The half-bridge LLC resonant converter of the second-phase to N-phase modules includes a switch tube Q i1 and switch tube Q i2 The primary switch bridge arm and resonant capacitor C ri , resonant inductor L ri 、Transformer T i , rectifier tube Q i3 , rectifier tube Q i4 and output capacitor C oi .

[0056] Switching tube Q i1 The drain is connected to the input voltage source V in The positive terminal of the transformer T i The same-name terminal of transformer T i The opposite-terminated resonant inductor L ri One end of the resonant inductor L ri The other end is connected to the resonant capacitor C ri One end of the switch tube Q i2 The drain and switch tube Q i1 The source of the capacitor is connected to the primary ground and the resonant capacitor C ri The other end of the transformer T iThe first secondary winding is terminated with the same name as the rectifier tube Q i3 The source of the rectifier tube Q i3 The drain is connected to the output capacitor C oi The positive terminal of the transformer T i The second secondary winding of the transformer is terminated with the same name i The opposite end of the first secondary winding and the output capacitor C oi The negative end of the transformer T i The second secondary winding is terminated with a rectifier tube Q i4 The source of the rectifier tube Q i4 The drain is connected to the output capacitor C oi The right end.

[0057] The auxiliary current sharing branch 10i includes an upper switch tube Q ia1 and the lower switch tube Q ia2 Form auxiliary switch bridge arm, auxiliary capacitor C ai and auxiliary inductor L ai , upper switch tube Q ia1 The drain of the switch is connected to the positive terminal of the input source, and the upper switch tube Q ia1 The source of the switch tube Q ia2 The drain of the auxiliary switch bridge arm forms the midpoint and is connected to the auxiliary capacitor C ai One end of the auxiliary capacitor C ai The other end is connected to the auxiliary inductor L ai One end of the auxiliary inductor L ai The other end is connected to the resonant capacitor C of the half-bridge LLC resonant converter of the i-phase module ri The second end of

[0058] The controller 101 receives the output voltage feedback signal V of the multi-phase interleaved parallel resonant converter. o_FB Or the total output current feedback signal I o_FB , synchronously control the switch tube Q of each phase module through the internal voltage loop or current loop j1 ~Q j2 The driving signal V Gj1 ~V Gj2 The frequency, j = 1, 2...N, makes the output voltage or total output current of the converter constant, and makes the phase angle between each phase module fixed to obtain the optimal ripple elimination effect; wherein, the control signal V Gj1 ~V Gj2 Each of these signals is a pairwise complementary square wave signal with a duty cycle close to 50% and a certain dead time. Furthermore, the controller 101 detects the deviation between the output current feedback signals of each phase module to adjust the phase difference of the drive signal between the auxiliary switch bridge arm of the i-th phase auxiliary current sharing branch and the primary switch bridge arm of the i-th phase module, thereby achieving output current sharing among the modules of each phase.

[0059] To facilitate the understanding of the current sharing method and the working principle of the implementation device of the multi-phase interleaved LLC resonant converter of the present invention by those skilled in the art, the fundamental wave approximation method is used to approximately analyze the circuit. Figure 6 The Figure 5 simplified AC circuit model of the shown embodiment is given.

[0060] Since the auxiliary capacitor C ai only plays the role of isolating the DC component, it can be ignored in this equivalent AC circuit model. Since the first-phase module is a conventional half-bridge LLC resonant converter, its analysis method is the same as that of the traditional LLC resonant converter.

[0061] For the i-th phase module, there is not only the voltage source as the input source of the single-phase LLC resonant converter, but also the auxiliary voltage source formed by the midpoint voltage of the auxiliary switch bridge arm after DC isolation by the auxiliary capacitor which also uses the auxiliary inductor L ai and the auxiliary capacitor C ai to form a series branch to generate an AC current source to charge and discharge the resonant capacitor C ri and thus change the energy in the i-th phase resonant cavity. Therefore, further using the superposition principle, the equivalent circuit of the i-th phase module can be decomposed, as Figure 5 shown. According to the superposition principle, the expression of the total AC output voltage of the i-th phase module referred to the primary side can be obtained as:

[0062]

[0063] Where:

[0064]

[0065] Among them, I oi is the output current of the i-th phase module. According to the superposition principle, the expression of the total AC output voltage of the i-th phase module referred to the primary side can be obtained as:

[0066]

[0067] It can be seen from (4) that the introduction of the auxiliary voltage source can adjust the AC output voltage of the i-th phase module, that is, change the voltage gain of this phase module.

[0068] At the same time, according to the fundamental wave approximation method, the expression (5) of the AC output voltage of the first-phase module referred to the primary side can be obtained.

[0069]

[0070] Also, because when the output currents of each phase module converter are equal (I o1 = I oi ), the amplitudes of the equivalent AC output voltages and should be equal, so the equation (6) can be obtained.

[0071]

[0072] Among them, n p is the number of turns of the primary winding of the transformer of each phase module, n s is the number of turns of the secondary winding of the transformer of each phase module, and the transformers of each phase module have the same number of winding turns. Therefore, assuming that each phase module has the optimal phase angle at this number of phases, that is, the phase is fixed, with the amplitude of the first-phase equivalent AC output voltage as the reference, by adjusting the phase of the voltage source , that is, the phase difference between the auxiliary switch bridge arm of the i-th phase and the primary switch bridge arm of the i-th phase, a suitable phase can always be found to make the equation (6) satisfied and achieve equal output currents of each phase module.

[0073] According to the above basic principle, the present invention also provides a wide voltage gain LLC resonant converter, and its specific embodiment is as shown in Figure 7 . Specifically, the wide voltage gain LLC resonant converter of the present invention includes: an LLC resonant converter 300 and an auxiliary branch 200.

[0074] The half-bridge LLC resonant converter 300 includes a switch bridge arm composed of a switching tube Q1 and a switching tube Q2, a resonant capacitor C r , a resonant inductor L r ?, a transformer T, a rectifying diode Q3, a rectifying diode Q4, and an output capacitor C o .

[0075] The drain of the switching tube Q1 is connected to the positive terminal of the input voltage source V in , its source is connected to the same-name terminal of the transformer T, the different-name terminal of the transformer T is connected to one end of the resonant inductor L r , the other end of the resonant inductor L r is connected to one end of the resonant capacitor C[[ID=5o]] r ; the drain of the switching tube Q2 is connected to the source of the switching tube Q1, and its source is connected to the primary ground and the other end of the resonant capacitor C r ;

[0076] The same-name terminal of the first secondary winding of the transformer T is connected to the source of the rectifying diode Q3, and the drain of the rectifying diode Q3 is connected to the output capacitor C oThe positive terminal of , the same-name terminal of the second secondary winding of transformer T is connected to the opposite-name terminal of the first secondary winding of transformer T and output capacitor C o The negative terminal of , the opposite-name terminal of the second secondary winding of transformer T is connected to the source electrode of rectifier tube Q4, and the drain electrode of rectifier tube Q4 is connected to output capacitor C o The positive terminal of ;

[0077] The auxiliary branch 200 includes upper switch tube Q a1 And lower switch tube Q a2 That form an auxiliary bridge arm. The drain electrode of Q a1 Is connected to the positive electrode of the input source, and the source electrode of Q a1 Is connected to the drain electrode of Q a2 To form the midpoint of the auxiliary switch bridge arm and connect one end of the auxiliary capacitor. The other end of auxiliary capacitor C a Is connected to one end of auxiliary inductor L a The other end of auxiliary inductor La is connected to the second end of resonant capacitor C r In the half-bridge LLC resonant converter 300; The source electrode of Q a2 Is connected to the primary ground.

[0078] According to the foregoing principle analysis, it can be known that the auxiliary bridge arm in the auxiliary branch 200 and the switch bridge arm in the half-bridge LLC resonant converter 300 are phase-shifted controlled, which can change the gain of the half-bridge LLC resonant converter 300, so that a wide voltage gain range can be achieved without changing the converter frequency.

[0079] According to the current-sharing method of the present invention described above, the second specific embodiment of the implementation device of the multi-phase interleaved parallel LLC resonant converter of the present invention can be obtained as Figure 8 Shown. It includes:

[0080] A multi-phase interleaved parallel LLC resonant converter composed of N half-bridge LLC resonant converter modules, N-1 phase-shifting inductor modules composed of auxiliary inductor L ai And auxiliary capacitor C ai Connected in series, and a controller 1001, where N is an integer greater than or equal to 2, and a phase-controllable AC current source is output through the phase-shifting inductor module.

[0081] Among them, the first end of resonant capacitor C ri In the i-th phase half-bridge LLC resonant converter module is connected to the source electrode of the lower tube of the primary switch bridge arm of the i-th phase half-bridge LLC resonant converter module, and its second end is connected to one end of the i-th phase phase-shifting inductor module. The other end of the i-th phase phase-shifting inductor module is connected to the midpoint of the primary switch bridge arm of the (i-1)-th phase half-bridge LLC resonant converter module;

[0082] Among them, i = 2, 3... N.

[0083] Preferably, the controller 1001 synchronously controls the switching frequency of the resonant converter according to the collected feedback signal V o_FB or I o_FB , and adjusts the output voltage or the total output current by means of the internal voltage loop or current loop. The phase difference of the drive signals of each phase resonant converter is adjusted by detecting the deviation between the output current feedback signals of each phase LLC resonant converter, that is, the interleaving angle between each phase is used to change the phase of the injected AC current source, so as to achieve current sharing of the output currents of each phase LLC resonant converter.

[0084] Compared with Figure 5 the first specific embodiment of the present invention shown Figure 8 the second specific embodiment shown uses the phase shift between each phase converter module to change the phase of the injected AC current source, so an additional auxiliary switch bridge arm is not required, and the circuit cost can be reduced. However, when the resonant parameter deviation of each phase converter module is large, the interleaving angle between the modules will deviate greatly from the optimized output current ripple cancellation angle, thus affecting the ripple cancellation effect.

[0085] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-phase interleaved LLC resonant converter device, characterized in that Including: A multi-phase interleaved parallel LLC resonant converter composed of N half-bridge LLC resonant converter modules, N - 1 auxiliary current sharing branches, and a controller; where N is an integer greater than or equal to 2; The auxiliary current sharing branch includes: an auxiliary switch bridge arm, an auxiliary inductor, and an auxiliary capacitor; The i-th phase half-bridge LLC resonant converter is connected with an auxiliary current sharing branch; The first end of the resonant capacitor in the i-th phase half-bridge LLC resonant converter is connected to the source of the lower transistor of the i-th phase primary switch bridge arm, and the second end is connected to the opposite-named end of the primary winding of the i-th phase transformer; The auxiliary switch bridge arm of the i-th phase auxiliary current sharing branch includes an upper switch transistor and a lower switch transistor. The drain of the upper switch transistor is connected to the positive pole of the input source, the source of the upper switch transistor is connected to the drain of the lower switch transistor to form the midpoint of the auxiliary switch bridge arm and is connected to one end of the auxiliary capacitor. The other end of the auxiliary capacitor is connected to one end of the auxiliary inductor, the other end of the auxiliary inductor is connected to the second end of the resonant capacitor in the i-th phase half-bridge LLC resonant converter, and the source of the lower switch transistor is connected to the primary ground; where, i = 2, 3... N.

2. The multi-phase interleaved LLC resonant converter device according to claim 1, wherein The described controller, according to the received output voltage feedback signal V of the multi-phase interleaved LLC resonant converter o_FB or the total output current feedback signal I o_FB , synchronously controls the driving signals V j1 ~Q j2 of each phase module through the voltage loop or current loop in the controller Gj1 ~V Gj2 to keep the output voltage or the total output current of the multi-phase interleaved LLC resonant converter constant, and make a fixed phase shift angle between each phase module to obtain the optimal ripple cancellation effect; where j = 1, 2... N; Drive signal V Gj1 ~V Gj2 are all square wave signals that are pairwise complementary with a duty cycle close to 50% and with a dead time left.

3. The multi-phase interleaved parallel LLC resonant converter device according to claim 2, wherein The controller adjusts the phase difference between the driving signals of the auxiliary switch bridge arm of the i-th phase auxiliary current sharing branch and the primary switch bridge arm of the i-th phase module by detecting the deviation between the output current feedback signals of each phase half-bridge LLC resonant converter, so as to achieve current sharing of the output currents of each phase module.

4. The multi-phase interleaved parallel LLC resonant converter device according to claim 1, characterized in that The described half-bridge LLC resonant converter includes a switching transistor Q 11 and a switching transistor Q 12 that form a switching bridge arm, a resonant capacitor C r1 , a resonant inductor L r1 , a transformer T1, a rectifying diode Q 13 , a rectifying diode Q 14 and an output capacitor C o1 ; Switching transistor Q 11 has its drain connected to the positive terminal of the input voltage source V in , its source connected to the same-named terminal of transformer T1, and the opposite-named terminal of transformer T1 connected to one end of the resonant inductor L r1 . The other end of the resonant inductor L r1 is connected to one end of the resonant capacitor C r1 . The drain of the switching transistor Q 12 is connected to the source of the switching transistor Q 11 , and its source is connected to the primary ground and the other end of the resonant capacitor C r1 . The same-name terminal of the first secondary winding of transformer T1 is connected to the source electrode of rectifying tube Q 13 , and the drain electrode of rectifying tube Q 13 is connected to the positive terminal of output capacitor C o1 . The same-name terminal of the second secondary winding of transformer T1 is connected to the opposite-name terminal of the first secondary winding of transformer T1 and the negative terminal of output capacitor C o1 . The opposite-name terminal of the second secondary winding of transformer T1 is connected to the source electrode of rectifying tube Q 14 , and the drain electrode of rectifying tube Q 14 is connected to the positive terminal of output capacitor C o1 .

5. The multi-phase interleaved LLC resonant converter device according to claim 4, wherein The i-th phase half-bridge LLC resonant converter includes an auxiliary current sharing branch 10i and a half-bridge LLC resonant converter; the half-bridge LLC resonant converter includes a switching transistor Q i1 and a switching transistor Q i2 that form a primary switching bridge arm, a resonant capacitor C ri , a resonant inductor L ri , a transformer T i , a rectifying diode Q i3 , a rectifying diode Q i4 and an output capacitor C oi ; Switching transistor Q i1 has its drain connected to the positive terminal of the input voltage source V in and its source connected to the same-named terminal of the transformer T i ; the different-named terminal of the transformer T i is connected to one end of the resonant inductor L ri and the other end of the resonant inductor L ri is connected to one end of the resonant capacitor C ri ; the drain of the switching transistor Q i2 is connected to the source of the switching transistor Q i1 and its source is connected to the primary ground and the other end of the resonant capacitor C ri ; the same-named terminal of the first secondary winding of the transformer T i is connected to the source of the rectifying diode Q i3 and the drain of the rectifying diode Q i3 is connected to the positive terminal of the output capacitor C oi ; the same-named terminal of the second secondary winding of the transformer T i is connected to the different-named terminal of the first secondary winding of the transformer T i and the negative terminal of the output capacitor C oi ; the different-named terminal of the second secondary winding of the transformer T i is connected to the source of the rectifying diode Q i4 [[ID=|38]]and the drain of the rectifying diode Q i4 is connected to the positive terminal of the output capacitor C oi ; The auxiliary current-sharing branch 10i includes an upper switching transistor Q ia1 and a lower switching transistor Q ia2 to form an auxiliary switching bridge arm, an auxiliary capacitor C ai and an auxiliary inductor L ai . The drain of the upper switching transistor Q ia1 is connected to the positive pole of the input source. The source of the upper switching transistor Q ia1 is connected to the drain of the lower switching transistor Q ia2 to form the midpoint of the auxiliary switching bridge arm and is connected to one end of the auxiliary capacitor C ai . The other end of the auxiliary capacitor C ai is connected to one end of the auxiliary inductor L ai . The other end of the auxiliary inductor L ai is connected to the second end of the resonant capacitor C ri of the i-th phase module half-bridge LLC resonant converter.

6. A wide-voltage-gain LLC resonant converter based on an auxiliary branch, characterized in that Including: A half-bridge LLC resonant converter and an auxiliary branch; The half-bridge LLC resonant converter includes a switching bridge arm composed of a switching transistor Q1 and a switching transistor Q2, a resonant capacitor C r , a resonant inductor L r , a transformer T, a rectifying diode Q3, a rectifying diode Q4, and an output capacitor C o ; the drain of the switching transistor Q1 is connected to the positive terminal of the input voltage source V in , its source is connected to the same-name terminal of the transformer T, and the different-name terminal of the transformer T is connected to one end of the resonant inductor L r ; the other end of the resonant inductor L r is connected to one end of the resonant capacitor C r ; the drain of the switching transistor Q2 is connected to the source of the switching transistor Q1, and its source is connected to the primary ground and the other end of the resonant capacitor C r ; The same-named end of the first secondary winding of transformer T is connected to the source electrode of rectifying tube Q3, and the drain electrode of rectifying tube Q3 is connected to the positive end of output capacitor C o The same-named end of the second secondary winding of transformer T is connected to the opposite-named end of the first secondary winding of transformer T and the negative end of output capacitor C o The opposite-named end of the second secondary winding of transformer T is connected to the source electrode of rectifying tube Q4, and the drain electrode of rectifying tube Q4 is connected to the positive end of output capacitor C o The positive end; The auxiliary branch includes an upper switching transistor Q a1 and a lower switching transistor Q a2 to form an auxiliary bridge arm. The drain of Q a1 is connected to the positive pole of the input source. The source of Q a1 is connected to the drain of Q a2 to form the midpoint of the auxiliary switch bridge arm and is connected to one end of an auxiliary capacitor C a . The other end of the auxiliary capacitor C a is connected to one end of an auxiliary inductor L a . The other end of the auxiliary inductor L a is connected to the second end of a resonant capacitor C r in the half-bridge LLC resonant converter; the source of Q a2 is connected to the primary ground.

7. The current sharing method for a multi-phase interleaved LLC resonant converter is applicable to the multi-phase interleaved LLC resonant converter device described in claim 1, and is characterized in that Including the following steps: Step 1: N half-bridge LLC resonant converters with the same rated parameters are used to form an N-phase parallel LLC resonant converter in the way of input parallel connection and output parallel connection, where N is an integer greater than or equal to 2; Step 2: Generate N - 1 phase-controllable AC current sources and inject them into the resonant capacitors of N - 1 phase LLC resonant converters respectively; Step 3: Adjust the phases of the injected AC current sources respectively according to the output current deviations of each phase LLC resonant converter, so as to achieve current sharing of the output currents of each phase LLC resonant converter.

8. A phase-shift controlled multi-phase interleaved LLC resonant converter, characterized in that, Including: A multi-phase interleaved parallel LLC resonant converter composed of N half-bridge LLC resonant converter modules, N - 1 phase-shifting inductor modules, and a controller; where N is an integer greater than or equal to 2; The described phase-shifting inductance module is composed of an auxiliary inductor L ai and an auxiliary capacitor C ai connected in series; The resonant capacitor C in the i-th phase half-bridge LLC resonant converter module ri The first end is connected to the source of the lower transistor of the primary switch bridge arm of the i-th phase half-bridge LLC resonant converter module, and its second end is connected to one end of the i-th phase phase-shifted inductor module. The other end of the i-th phase phase-shifted inductor module is connected to the midpoint of the primary switch bridge arm of the (i - 1)-th phase half-bridge LLC resonant converter module; where, i = 2, 3... N.

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