Multi-phase switching power supply conversion circuit and control method thereof

Abstract

The invention relates to the technical field of electric energy conversion, and discloses a multiphase switching power supply conversion circuit and a control method thereof, and the multiphase switching power supply conversion circuit, the multiphase switching power supply conversion circuit comprises a switching circuit, a transformer, a first resonant circuit, a second resonant circuit and a third resonant circuit, and the switching circuit comprises four bridge arms. According to the circuit structure and the control method, the switching loss of the switching tube can be reduced in a light no-load working state, so that the light no-load loss is reduced, the light no-load efficiency is further improved, and the temperature rise is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy conversion, and in particular to a multi-phase switching power supply conversion circuit. and Control method. Background Art

[0002] With the rapid development of power electronics technology, the demand for high-power switching power supply products is increasing day by day, especially in applications such as photovoltaics, wind power, and electric vehicle on-board chargers. The power level of the required power-level converters is gradually increasing, and the design requirements for power electronic converters are also becoming higher and higher.

[0003] The resonant mode power conversion circuit uses a resonant network, which enables the switch tube to have zero voltage or zero current switching conditions, which can reduce switching losses, especially in high-frequency application scenarios, and has a relatively obvious efficiency advantage. At the same time, as the switching frequency increases, the product size is also reduced. Therefore, the resonant mode power conversion circuit has been more and more widely used and is one of the key solutions to achieve high efficiency and high power density.

[0004] The existing three-phase LLC resonant converter circuit topology is as follows: Figure 1 As shown, this topology is formed by connecting three half-bridge LLC circuits in parallel, with the three working circuits being exactly the same and the current phases differing by 120°. Its circuit topology includes: switch circuit (including: switches S1-S6), capacitors (including: capacitors Cr1, Cr2, and Cr3), inductors (including: inductors Lr1, Lr2, and Lr3), transformers, and rectifier circuits (including 6 diodes or switch tubes), etc. Compared with the single-phase LLC resonant converter topology, this circuit topology can be applied to a larger power level and has a smaller output ripple. However, due to the inherent structure of this topology, when working with light no-load, one of the control methods is to increase the operating frequency to the highest frequency to reduce the gain, but the switching loss of this control method is large; another control method is to switch the three-phase operation to the two-phase working state to reduce the switching loss of the switch tube. This method can reduce the switching loss to a certain extent, but there are still two-phase switch bridge arms working. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a multi-phase switching power supply conversion circuit and a control method thereof, which can solve the deficiencies in the prior art to a certain extent.

[0006] As a first aspect of the present invention, the technical solution of the embodiment of the circuit structure provided is as follows:

[0007] A multi-phase switching power supply conversion circuit, comprising:

[0008] The first switch circuit comprises a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm; the first, second, third and fourth bridge arms each comprise two switch devices connected in series;

[0009] Transformers, including a first transformer, a second transformer and a third transformer;

[0010] A first resonant circuit, comprising a first inductor and a first capacitor connected in series, wherein the first resonant circuit is connected in series with the primary winding of the first transformer and connected between a midpoint of the first bridge arm and a midpoint of the fourth bridge arm;

[0011] A second resonant circuit, comprising a second inductor and a second capacitor connected in series, wherein the second resonant circuit is connected in series with a primary winding of a second transformer and connected between a midpoint of the second bridge arm and a midpoint of the fourth bridge arm;

[0012] The third resonant circuit includes a third inductor and a third capacitor. The third resonant circuit is connected in series with the primary winding of the third transformer and is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm.

[0013] Further, the first end of the primary winding of the first transformer, the first end of the primary winding of the second transformer, the first end of the primary winding of the third transformer, the first end of the secondary winding of the first transformer, the first end of the secondary winding of the second transformer and the first end of the secondary winding of the third transformer are the same-named ends; the second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer, the second end of the primary winding of the third transformer, the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are the same-named ends.

[0014] The second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer and the second end of the primary winding of the third transformer are electrically connected together, so that the primary winding of the first transformer, the primary winding of the second transformer and the primary winding of the third transformer form a star connection structure; the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are electrically connected together, so that the secondary winding of the first transformer, the secondary winding of the second transformer and the secondary winding of the third transformer form a star connection structure.

[0015] Further, the first end of the primary winding of the first transformer, the first end of the primary winding of the second transformer, the first end of the primary winding of the third transformer, the first end of the secondary winding of the first transformer, the first end of the secondary winding of the second transformer and the first end of the secondary winding of the third transformer are the same-named ends; the second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer, the second end of the primary winding of the third transformer, the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are the same-named ends.

[0016] The second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer and the second end of the primary winding of the third transformer are electrically connected together, so that the primary winding of the first transformer, the primary winding of the second transformer and the primary winding of the third transformer form a star connection structure; the second end of the secondary winding of the first transformer is electrically connected to the first end of the secondary winding of the second transformer, the second end of the secondary winding of the second transformer is electrically connected to the first end of the secondary winding of the third transformer, and the second end of the secondary winding of the third transformer is electrically connected to the first end of the secondary winding of the first transformer, so that the secondary winding of the first transformer, the secondary winding of the second transformer and the secondary winding of the third transformer form a triangle connection structure.

[0017] Furthermore, the multi-phase switching power supply conversion circuit is further provided with a second switching circuit, a fourth resonant circuit, a fifth resonant circuit and a sixth resonant circuit;

[0018] The second switch circuit includes a fifth bridge arm, a sixth bridge arm, a seventh bridge arm and an eighth bridge arm;

[0019] The fourth resonant circuit comprises a fourth inductor and a fourth capacitor connected in series, and the fourth resonant circuit is connected in series with the secondary winding of the first transformer and connected between the midpoint of the bridge arm of the sixth bridge arm and the midpoint of the bridge arm of the fifth bridge arm;

[0020] The fifth resonant circuit comprises a fifth inductor and a fifth capacitor connected in series, and the fifth resonant circuit is connected in series with the secondary winding of the second transformer and connected between the midpoint of the seventh bridge arm and the midpoint of the fifth bridge arm;

[0021] The sixth resonant circuit includes a sixth inductor and a sixth capacitor. The sixth resonant circuit is connected in series with the secondary winding of the third transformer and is connected between the midpoint of the eighth bridge arm and the midpoint of the fifth bridge arm.

[0022] The present invention also provides a multi-phase switching power supply conversion circuit, which includes:

[0023] A first switch circuit comprises a first bridge arm, a second bridge arm and a third bridge arm;

[0024] Transformers, including a first transformer, a second transformer and a third transformer;

[0025] A first resonant circuit comprises a first inductor and a first capacitor connected in series, wherein the first resonant circuit is connected in series with a primary winding of the first transformer;

[0026] A second resonant circuit, comprising a second inductor and a second capacitor connected in series, wherein the second resonant circuit is connected in series with the primary winding of the second transformer;

[0027] A third resonant circuit, comprising a third inductor and a third capacitor, wherein the first resonant circuit is connected in series with the primary winding of the third transformer;

[0028] The second switch circuit includes a fourth bridge arm, a fifth bridge arm, a sixth bridge arm and a seventh bridge arm;

[0029] a fourth resonant circuit, comprising a fourth inductor and a fourth capacitor connected in series, wherein the fourth resonant circuit is connected in series with the secondary winding of the first transformer and connected between a midpoint of the fifth bridge arm and a midpoint of the fourth bridge arm;

[0030] a fifth resonant circuit, comprising a fifth inductor and a fifth capacitor connected in series, wherein the fifth resonant circuit is connected in series with the secondary winding of the second transformer and connected between a bridge arm midpoint of the sixth bridge arm and a bridge arm midpoint of the fourth bridge arm;

[0031] The sixth resonant circuit comprises a sixth inductor and a sixth capacitor. The sixth resonant circuit is connected in series with the secondary winding of the third transformer and then connected between the midpoint of the seventh bridge arm and the midpoint of the fourth bridge arm.

[0032] The present invention further provides a control method for the multi-phase switching power supply conversion circuit, comprising:

[0033] When the multi-phase switching power supply conversion circuit is in a light load or no-load state, the lower switch tube in the fourth bridge arm works, and the upper switch tube in the fourth bridge arm does not work, only one of the first, second, and third bridge arms works, and the driving pulse of the upper switch tube and the driving pulse of the lower switch tube of the bridge arm in the working state among the first, second, and third bridge arms are complementary, the driving pulse of the lower switch tube in the fourth bridge arm is the same as the driving pulse of the upper switch tube of the bridge arm in the working state among the first, second, and third bridge arms, or the lower switch tube in the fourth bridge arm remains in a normally open state.

[0034] The present invention also provides a control method for the multi-phase switching power supply conversion circuit, including: when the multi-phase switching power supply conversion circuit is in a light load or no-load state, the upper switch tube in the fourth bridge arm is working, the lower switch tube in the fourth bridge arm is not working, only the lower switch tube in one of the first, second and third bridge arms is working, and the driving pulse of the lower switch tube in the first, second and third bridge arms that is in a working state is the same as the driving pulse of the upper switch tube in the fourth bridge arm.

[0035] The present invention further provides a control method for the multi-phase switching power supply conversion circuit, including: when the multi-phase switching power supply conversion circuit is in a light load or no-load state, the fourth bridge arm works, only one of the first, second and third bridge arms works, and the bridge arm in the working state among the first, second and third bridge arms, the driving pulse of the upper switch tube and the driving pulse of the lower switch tube are complementary, the driving pulse of the upper switch tube is the same as the driving pulse of the lower switch tube in the fourth bridge arm, and the driving pulse of the lower switch tube is the same as the driving pulse of the upper switch tube in the fourth bridge arm.

[0036] Further, when the multi-phase switching power supply conversion circuit is in a full load or heavy load state, the driving pulse phases of the upper switch tube in the first bridge arm, the upper switch tube in the second bridge arm, and the upper switch tube in the third bridge arm are 120° apart in sequence; the driving pulse phases of the lower switch tube in the first bridge arm, the lower switch tube in the second bridge arm, and the lower switch tube in the third bridge arm are 120° apart in sequence;

[0037] When the multi-phase switching power supply conversion circuit is in a half-load state, any two of the first, second, and third bridge arms are in operation, and the driving pulse phases of the upper switch tube in one of the bridge arms in operation and the upper switch tube in the other bridge arm in operation differ by 180°, and the driving pulse phases of the lower switch tube in one of the bridge arms and the lower switch tube in the other bridge arm differ by 180°.

[0038] Furthermore, the driving pulses of the upper switch tube and the lower switch tube in the first bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time; the driving pulses of the upper switch tube and the lower switch in the second bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time; the driving pulses of the upper switch tube and the lower switch tube in the third bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The circuit structure and control method of the present invention can reduce the switching loss of the switch tube under the light no-load working state, thereby reducing the light no-load loss, further improving the light no-load efficiency, and reducing the temperature rise. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the circuit diagram of the existing three-phase interleaved LLC;

[0042] Figure 2 A circuit structure diagram of a multi-phase switching power supply conversion circuit proposed by the present invention;

[0043] Figure 3 This is a star connection structure diagram of the transformer proposed by the present invention;

[0044] Figure 4 This is a diagram of the transformer triangle connection structure proposed by the present invention;

[0045] Figure 5 This is the control working state of mode 1 of the present invention under light load or no load conditions;

[0046] Figure 6 This is the control working state of mode 2 of the present invention under light load or no load conditions;

[0047] Figure 7 This is the control working state of mode 3 of the present invention under light load or no load conditions;

[0048] Figure 8 The three-phase mode driving logic timing proposed by the present invention;

[0049] Fig. 9 This is the control working state of mode 1 of the present invention under full load or heavy load conditions;

[0050] Fig.10 This is the control working state of mode 2 of the present invention under full load or heavy load conditions;

[0051] Fig.11 This is the control working state of mode 3 of the present invention under full load or heavy load conditions;

[0052] Fig.12 The two-phase mode driving logic timing proposed by the present invention;

[0053] Fig.13 This is the control working state of mode 1 of the present invention under half load;

[0054] Fig.14 This is the control working state of mode 2 of the present invention under half load;

[0055] Fig.15 This is the control working state of mode 3 of the present invention under half load;

[0056] Fig.16 The circuit structure of the second embodiment of the present invention;

[0057] Fig.17 This is the control working state of mode 1 of the second embodiment of the present invention under light load or no load conditions;

[0058] Fig.18 This is the control working state of mode 2 of the second embodiment proposed by the present invention under light load or no load conditions;

[0059] Fig.19 This is the control working state of mode 3 of the second embodiment of the present invention under light load or no load conditions;

[0060] Fig. 20 This is the circuit structure of the third embodiment of the present invention. DETAILED DESCRIPTION

[0061] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0063] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application are described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0064] It should be understood that, in the specification, claims and drawings, when a step is described as being connected to another step, the step may be directly connected to the other step, or be connected to the other step through a third step; when an element / unit is described as being "connected" to another element / unit, the element / unit may be "directly connected" to the other element / unit, or be "connected" to the other element / unit through a third element / unit.

[0065] In addition, the drawings of the present disclosure are only schematic diagrams of the present disclosure and are not necessarily drawn to scale. The same symbols in the drawings represent the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented using software, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontrollers.

[0066] First embodiment

[0067] refer to Figure 2 The embodiment of the present invention provides a multi-phase switching power supply conversion circuit, which includes: a first input terminal, a second input terminal, a first output terminal, a second output terminal, a switching circuit, a transformer, a resonant circuit and a rectifier circuit. The multi-phase switching power supply conversion circuit in this embodiment is a three-phase switching power supply conversion circuit.

[0068] The switching circuit includes a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm, wherein the first bridge arm includes a switch tube S1 (upper switch tube) and a switch tube S2 (lower switch tube) connected in series; the second bridge arm includes a switch tube S3 (upper switch tube) and a switch tube S4 (lower switch tube) connected in series; the third bridge arm includes a switch tube S5 (upper switch tube) and a switch tube S6 (lower switch tube) connected in series; the fourth bridge arm includes a switch tube S7 (upper switch tube) and a switch tube S8 (lower switch tube) connected in series.

[0069] The transformer includes a first transformer T1, a second transformer T2 and a third transformer T3. The first end of the primary winding of the first transformer T1, the first end of the primary winding of the second transformer T2, the first end of the primary winding of the third transformer T3, the first end of the secondary winding of the first transformer T1, the first end of the secondary winding of the second transformer T2 and the first end of the secondary winding of the third transformer T3 are the same end; the second end of the primary winding of the first transformer T1, the second end of the primary winding of the second transformer T2, the second end of the primary winding of the third transformer T3, the second end of the secondary winding of the first transformer T1, the second end of the secondary winding of the second transformer T2 and the second end of the secondary winding of the third transformer T3 are the same end.

[0070] The second end of the primary winding of the first transformer T1, the second end of the primary winding of the second transformer T2, and the second end of the primary winding of the third transformer T3 are electrically connected together, so that the primary winding of the first transformer T1, the primary winding of the second transformer T2, and the primary winding of the third transformer T3 form a star connection structure (such as Figure 3As shown); the second end of the secondary winding of the first transformer T1, the second end of the secondary winding of the second transformer T2 and the second end of the secondary winding of the third transformer T3 are electrically connected together, so that the secondary winding of the first transformer T1, the secondary winding of the second transformer T2 and the secondary winding of the third transformer T3 form a star connection structure.

[0071] In other embodiments, the secondary winding of the first transformer T1, the secondary winding of the second transformer T2 and the secondary winding of the third transformer T3 may also form a triangle connection structure (eg Figure 4 As shown), that is, the second end of the secondary winding T1 of the first transformer is electrically connected to the first end of the secondary winding of the second transformer T2, and the second end of the secondary winding of the second transformer T2 is electrically connected to the first end of the secondary winding of the third transformer T3.

[0072] The resonance circuit includes a first resonance circuit, a second resonance circuit and a third resonance circuit.

[0073] The first resonant circuit includes a first inductor Lr1 and a first capacitor Cr1, which are connected in series with the primary winding of the first transformer T1 and connected between the midpoint a of the first bridge arm and the midpoint d of the fourth bridge arm; the second resonant circuit includes a second inductor Lr2 and a second capacitor Cr2, which are connected in series with the primary winding of the second transformer T2 and connected between the midpoint b of the second bridge arm and the midpoint d of the fourth bridge arm; the third resonant circuit includes a third inductor Lr3 and a third capacitor Cr3; the third resonant circuit is connected in series with the primary winding of the third transformer T3 and connected between the midpoint c of the third bridge arm and the midpoint d of the fourth bridge arm.

[0074] The rectifier circuit includes a first rectifier bridge arm, a second rectifier bridge arm and a third rectifier bridge arm, wherein the first rectifier bridge arm includes a diode D1 and a diode D2 connected in series, the second rectifier bridge arm includes a diode D3 and a diode D4 connected in series, and the third rectifier bridge arm includes a diode D5 and a diode D6 connected in series. The bridge arm midpoint e of the first rectifier bridge arm is connected to the first end of the secondary winding of the transformer T1, the bridge arm midpoint f of the second rectifier bridge arm is connected to the first end of the secondary winding of the transformer T2, and the bridge arm midpoint g of the third rectifier bridge arm is connected to the first end of the secondary winding of the transformer T3.

[0075] Figure 2 The multi-phase switching power conversion circuit shown is Figure 1 Compared with the existing three-phase resonant converter shown in Figure 2 The multi-phase switching power supply conversion circuit shown has an additional switching bridge arm, that is, a fourth bridge arm is added, and a bridge arm midpoint d of the fourth bridge arm is connected to a common point of the multi-phase switching power supply conversion circuit. Figure 2The multi-phase switching power supply conversion circuit shown can reduce the switching loss of the switch tube under the light no-load working state, reduce the light no-load loss, further improve the light no-load efficiency, and reduce the temperature rise.

[0076] In specific implementation, under light load or no-load conditions, the multi-phase switching power supply conversion circuit has the following three control modes, which are specifically described below.

[0077] Method 1: Any one of the first bridge arm, the second bridge arm and the third bridge arm and the lower switch tube of the fourth bridge arm are working, and the upper switch tubes of the remaining two bridge arms and the fourth bridge arm are not working, so as to realize single-phase operation. Figure 5 As shown, the first bridge arm is working, the driving pulse of the switch tube S1 is the same as the driving pulse of the switch tube S8, and without considering the dead zone, the driving pulse of the switch tube S1 and the driving pulse of the switch tube S2 are complementary.

[0078] Specifically, when the switch tube S1 is turned on, the input voltage Vin is excited through the drain-source of the switch tube S1, the common point, the primary winding of the first transformer, the resonant inductor, the resonant capacitor, and the drain-source of the switch tube S8; when the switch tubes S1 and S8 are both turned off, the first inductor Lr1 returns to the other end of the first inductor Lr1 through the first capacitor Cr1, the drain-source of the switch tube S2, the body diode of the switch tube S8, the common point, and the primary winding of the first transformer.

[0079] Under this control mode, compared with the situation that the traditional three-phase interleaved LLC requires at least two phases of bridge arms to be opened, this embodiment can reduce the number of switch tubes involved in the work, reduce the conduction loss and switching loss, and thus improve the light no-load efficiency.

[0080] It should be noted that the lower switch tubes of the first bridge arm, the second bridge arm and the third bridge arm can also work in rotation, and the rotation method can be controlled by information such as working time or temperature.

[0081] Mode 2: The lower switch tube of any one of the first bridge arm, the second bridge arm and the third bridge arm works, the upper switch tube in the fourth bridge arm works, and the lower switch tube of the fourth bridge arm does not work. Figure 6 As shown, the switch tube S7 in the fourth bridge arm is working, the switch tube S8 in the fourth bridge arm is not working, the switch tube S2 in the first bridge arm is working, and the driving pulse of the switch tube S2 is the same as the driving pulse of the switch tube S7. Figure 6 The switching method shown can also realize single-phase control.

[0082] Mode 3: any one of the first bridge arm, the second bridge arm and the third bridge arm and the fourth bridge arm work, and the remaining two bridge arms do not work, such as Figure 7As shown, the first bridge arm is working, the driving pulse of the switch tube S1 is the same as the driving pulse of the switch tube S8, the driving pulse of the switch tube S2 is the same as the driving pulse of the switch tube S7, and without considering the dead zone, the driving pulse of the switch tube S1 and the driving pulse of the switch tube S2 are complementary.

[0083] Specifically, when the switch tube S1 and the switch tube S8 are turned on and the switch tube S2 and the switch tube S7 are turned off, the input voltage Vin passes through the drain-source electrode of the switch tube S1, the first capacitor Cr1, the first inductor Lr1, the primary winding of the first transformer T1, the common point, and the drain-source electrode of the switch tube S8 to form a loop for excitation; when the switch tube S1 and the switch tube S8 are turned off and the switch tube S2 and the switch tube S7 are turned on, the input voltage Vin passes through the drain-source electrode of the switch tube S7, the common point, the primary winding of the first transformer T1, the first inductor Lr1, the first capacitor Cr1, and the drain-source electrode of the switch tube S2 to form a loop for demagnetization.

[0084] Under this control mode, compared with the situation that the traditional three-phase interleaved LLC requires at least two phase bridge arms to be opened, this embodiment can reduce the number of transformer windings involved in the work and improve the utilization rate of the transformer.

[0085] It should be noted that, under this control method, the lower switch tubes of the first bridge arm, the second bridge arm and the third bridge arm can also work in rotation, and the rotation method can be controlled by information such as working time or temperature.

[0086] In specific implementation, under full load or heavy load conditions, the multi-phase switching power supply conversion circuit has the following three control modes, all of which adopt three-phase interleaved control mode, such as Figure 8 The following is a detailed description of these three control methods.

[0087] Method 1: The first bridge arm, the second bridge arm, and the third bridge arm work, and the fourth bridge arm does not work. Fig. 9 As shown, the driving pulse phases of the switch tubes S1, S3, and S5 differ by 120° respectively. Without considering the dead zone, the driving pulses of the switch tubes S2, S4, and S6 are complementary to the driving pulses of the switch tubes S1, S3, and S5 respectively.

[0088] Mode 2: The upper switch tubes of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm work, such as Fig.10 As shown, the driving pulse phases of the switch tubes S1, S3, and S5 differ by 120° respectively. Without considering the dead zone, the driving pulses of the switch tubes S2, S4, and S6 are complementary to the driving pulses of the switch tubes S1, S3, and S5, respectively, and the switch tube S7 is continuously turned on.

[0089] Mode 3: The lower switch tubes of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm work, such as Fig.11 The driving pulse phases of the switch tubes S1, S3 and S5 differ by 120° respectively. Without considering the dead zone, the driving pulses of the switch tubes S2, S4 and S6 are complementary to the driving pulses of the switch tubes S1, S3 and S5 respectively, and the switch tube S8 is continuously turned on.

[0090] In specific implementation, under half-load conditions, the multi-phase switching power supply conversion circuit has the following three control modes, all of which adopt a two-phase interleaved control mode, such as Fig.12 The following is a detailed description of these three control methods.

[0091] Method 1: Any two of the first bridge arm, the second bridge arm and the third bridge arm are working, and the remaining bridge arm and the fourth bridge arm are not working, such as Fig.13 As shown, the first bridge arm and the second bridge arm are working, wherein the driving pulse phases of the switch tube S1 and the switch tube S3 are 180° apart, respectively, and without considering the dead zone, the driving pulses of the switch tube S2 and the switch tube S4 are complementary to the driving pulses of the switch tube S1 and the switch tube S3. It should be noted that any two working bridge arms among the first bridge arm, the second bridge arm and the third bridge arm can work in rotation.

[0092] Mode 2: Any two of the first bridge arm, the second bridge arm and the third bridge arm are working, the upper switch tube of the fourth bridge arm is working, and the remaining bridge arm and the lower switch tube of the fourth bridge arm are not working, such as Fig.14 As shown, the first bridge arm and the second bridge arm are working, wherein the driving pulse phases of the switch tubes S1 and S3 are 180° apart, respectively, and without considering the dead zone, the driving pulses of the switch tubes S2 and S4 are complementary to the driving pulses of the switch tubes S1 and S3, respectively, and the switch tube S7 is continuously turned on. It should be noted that any two working bridge arms among the first bridge arm, the second bridge arm and the third bridge arm can work in rotation.

[0093] Mode 3: When any two of the first bridge arm, the second bridge arm and the third bridge arm are working, the lower switch tube of the fourth bridge arm is working, and the remaining bridge arm and the upper switch tube of the fourth bridge arm are not working, Fig.15 As shown, the first bridge arm and the second bridge arm are working, wherein the driving pulse phases of the switch tubes S1 and S3 are 180° apart, respectively. Without considering the dead zone, the driving pulses of the switch tubes S2 and S4 are complementary to the driving pulses of the switch tubes S1 and S3, respectively, and the switch tube S8 is continuously turned on. It should be noted that any two working bridge arms among the first bridge arm, the second bridge arm and the third bridge arm can work in rotation.

[0094] Second embodiment

[0095] A multi-phase switching power supply conversion circuit provided in the second embodiment of the present invention is a new circuit topology extending from the concept of the present invention. Fig.16 As shown, the difference from the first embodiment of the present invention is that the primary side uses three switch bridge arms, the secondary side adds a new switch bridge arm, and the secondary side is a switch tube. At this time, the primary side connection structure of the transformer can be star or triangle.

[0096] Specifically, the multi-phase switching power supply conversion circuit includes: a first switching circuit, a second switching circuit, a transformer, a first resonant circuit, a second resonant circuit, a third resonant circuit, a fourth resonant circuit, a fifth resonant circuit and a sixth resonant circuit.

[0097] The first switch circuit includes a first bridge arm, a second bridge arm and a third bridge arm; the first bridge arm includes a switch tube S1 and a switch tube S2 connected in series; the second bridge arm includes a switch tube S3 and a switch tube S4 connected in series; the third bridge arm includes a switch tube S5 and a switch tube S6 connected in series.

[0098] The transformer includes a first transformer T1, a second transformer T2 and a third transformer T3.

[0099] The first resonant circuit includes a first inductor Lr1 and a first capacitor Cr1 connected in series, and the first resonant circuit is connected in series with the primary winding of the first transformer T1; the second resonant circuit includes a second inductor Lr2 and a second capacitor Cr2 connected in series, and the second resonant circuit is connected in series with the primary winding of the second transformer T2; the third resonant circuit includes a third inductor Lr3 and a third capacitor Cr3, and the first resonant circuit is connected in series with the primary winding of the third transformer T3.

[0100] The second switching circuit includes a fourth bridge arm, a fifth bridge arm, a sixth bridge arm and a seventh bridge arm; the fourth bridge arm includes a switch tube S15 and a switch tube S16 connected in series; the fifth bridge arm includes a switch tube S9 and a switch tube S10 connected in series; the sixth bridge arm includes a switch tube S11 and a switch tube S12 connected in series; the seventh bridge arm includes a switch tube S13 and a switch tube S14 connected in series.

[0101] The fourth resonant circuit includes a fourth inductor Lr4 and a fourth capacitor Cr4 connected in series, and the fourth resonant circuit is connected in series with the secondary winding of the first transformer T1 and connected between the bridge arm midpoint e of the fifth bridge arm and the bridge arm midpoint h of the fourth bridge arm; the fifth resonant circuit includes a fifth inductor Lr5 and a fifth capacitor Cr5 connected in series, and the fifth resonant circuit is connected in series with the secondary winding of the second transformer T2 and connected between the bridge arm midpoint f of the sixth bridge arm and the bridge arm midpoint h of the fourth bridge arm; the sixth resonant circuit includes a sixth inductor Lr6 and a sixth capacitor Cr6, and the sixth resonant circuit is connected in series with the secondary winding of the third transformer T3 and connected between the bridge arm midpoint g of the seventh bridge arm and the bridge arm midpoint h of the fourth bridge arm.

[0102] The multi-phase switching power supply conversion circuit in this embodiment is a circuit structure of bidirectional transmission, and its main advantages are reflected in the transmission from the secondary side to the primary side and the light no-load working state, specifically:

[0103] Mode 1: Any one of the fifth bridge arm, the sixth bridge arm and the seventh bridge arm of the second switch circuit and the lower switch tube of the fourth bridge arm work, and the remaining two bridge arms and the upper switch tube of the fourth bridge arm do not work, so as to realize single-phase operation. Fig.17 As shown, the fifth bridge arm is working, the driving pulse of the switch tube S9 is the same as the driving pulse of the switch tube S16, and without considering the dead zone, the driving pulse of the switch tube S9 and the driving pulse of the switch tube S10 are complementary.

[0104] Specifically, when the switch tube S9 is turned on, the reverse input voltage Vin' is excited through the drain-source of the switch tube S9, the resonant capacitor, the resonant inductor, the primary winding of the first transformer, the common point, and the drain-source of the switch tube S16; when the switch tube S9 and the switch tube S16 are both turned off, the fourth inductor Lr4 returns to the other end of the fourth inductor Lr4 through the fourth capacitor Cr4, the drain-source of the switch tube S10, the body diode of the switch tube S16, the common point, and the primary winding of the fourth transformer.

[0105] Under this control mode, the beneficial effects are similar to those of the corresponding control mode of the first embodiment. Compared with the traditional three-phase interleaved LLC which requires at least two phases of bridge arms to be opened, this embodiment can reduce the number of switching tubes involved in the work, reduce conduction loss and switching loss, and thus improve the light no-load efficiency.

[0106] It should be noted that the lower switch tubes of the fifth bridge arm, the sixth bridge arm and the seventh bridge arm can also work in rotation, and the rotation method can be controlled by information such as working time or temperature.

[0107] Mode 2: The lower switch tube of any one of the fifth bridge arm, the sixth bridge arm and the seventh bridge arm works, the upper switch tube in the fourth bridge arm works, and the lower switch tube of the fourth bridge arm does not work. Fig.18As shown, the switch tube S15 in the fourth bridge arm is working, the switch tube S16 in the fourth bridge arm is not working, the switch tube S10 in the fifth bridge arm is working, and the driving pulse of the switch tube S10 is the same as the driving pulse of the switch tube S15. Fig.18 The switching method shown can also realize single-phase control.

[0108] Mode 3: any one of the fifth bridge arm, the sixth bridge arm and the seventh bridge arm and the fourth bridge arm work, and the remaining two bridge arms do not work, such as Fig.19 As shown, the fifth bridge arm is working, the driving pulse of the switch tube S9 is the same as the driving pulse of the switch tube S16, the driving pulse of the switch tube S10 is the same as the driving pulse of the switch tube S15, and without considering the dead zone, the driving pulse of the switch tube S9 and the driving pulse of the switch tube S10 are complementary.

[0109] Specifically, when the switch tube S9 and the switch tube S16 are turned on and the switch tube S10 and the switch tube S15 are turned off, the input voltage Vin' forms a loop through the drain-source electrode of the switch tube S9, the fourth capacitor Cr4, the fourth inductor Lr4, the primary winding of the first transformer T1, the common point, and the drain-source electrode of the switch tube S16 for excitation; when the switch tube S9 and the switch tube S16 are turned off and the switch tube S10 and the switch tube S15 are turned on, the input voltage Vin' forms a loop through the drain-source electrode of the switch tube S15, the common point, the primary winding of the first transformer T1, the fourth inductor Lr4, the fourth capacitor Cr4, and the drain-source electrode of the switch tube S10 for demagnetization.

[0110] Under this control mode, compared with the situation that the traditional three-phase interleaved LLC requires at least two phase bridge arms to be opened, this embodiment can reduce the number of transformer windings involved in the work and improve the utilization rate of the transformer.

[0111] Third embodiment

[0112] A multi-phase switching power supply conversion circuit provided in the second embodiment of the present invention is a new circuit topology extending from the concept of the present invention. Fig. 20 As shown, the difference from the first embodiment of the present invention is that a switch bridge arm is newly added to the secondary side, and the secondary side is a switch tube.

[0113] That is, the switching circuit located on the secondary side includes a fifth bridge arm, a sixth bridge arm, a seventh bridge arm and an eighth bridge arm; the fifth bridge arm includes a switch tube S15 and a switch tube S16 connected in series; the sixth bridge arm includes a switch tube S9 and a switch tube S10 connected in series; the seventh bridge arm includes a switch tube S11 and a switch tube S12 connected in series; and the eighth bridge arm includes a switch tube S13 and a switch tube S14 connected in series.

[0114] The fourth resonant circuit includes a fourth inductor Lr4 and a fourth capacitor Cr4 connected in series. The fourth resonant circuit is connected in series with the secondary winding of the first transformer T1 and connected between the bridge arm midpoint e of the sixth bridge arm and the bridge arm midpoint h of the fifth bridge arm; the fifth resonant circuit includes a fifth inductor Lr5 and a fifth capacitor Cr5 connected in series. The fifth resonant circuit is connected in series with the secondary winding of the second transformer T2 and connected between the bridge arm midpoint f of the seventh bridge arm and the bridge arm midpoint h of the fifth bridge arm; the sixth resonant circuit includes a sixth inductor Lr6 and a sixth capacitor Cr6. The sixth resonant circuit is connected in series with the secondary winding of the third transformer T3 and connected between the bridge arm midpoint g of the eighth bridge arm and the bridge arm midpoint h of the fifth bridge arm.

[0115] This circuit topology is a bidirectional transmission circuit structure, and its main advantage over the traditional solution is the light no-load working condition. In forward transmission, the working method is the same as the first embodiment, and in reverse transmission, the working method is the same as the second embodiment, which will not be described here.

[0116] The terms used in the above embodiments are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or nature of the invention, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A multi-phase switching power supply conversion circuit, characterized in that: include: The first switch circuit comprises a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm; the first, second, third and fourth bridge arms each comprise two switch devices connected in series; Transformers, including a first transformer, a second transformer and a third transformer; A first resonant circuit, comprising a first inductor and a first capacitor connected in series, wherein the first resonant circuit is connected in series with the primary winding of the first transformer and connected between a midpoint of the first bridge arm and a midpoint of the fourth bridge arm; A second resonant circuit comprises a second inductor and a second capacitor connected in series, wherein the second resonant circuit is connected in series with the primary winding of the second transformer and connected between a midpoint of the second bridge arm and a midpoint of the fourth bridge arm; and The third resonant circuit includes a third inductor and a third capacitor connected in series. The third resonant circuit is connected in series with the primary winding of the third transformer and is connected between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm.

2. The multi-phase switching power supply conversion circuit according to claim 1, characterized in that: The first end of the primary winding of the first transformer, the first end of the primary winding of the second transformer, the first end of the primary winding of the third transformer, the first end of the secondary winding of the first transformer, the first end of the secondary winding of the second transformer and the first end of the secondary winding of the third transformer are the same-named ends; the second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer, the second end of the primary winding of the third transformer, the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are the same-named ends; The second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer and the second end of the primary winding of the third transformer are electrically connected together, so that the primary winding of the first transformer, the primary winding of the second transformer and the primary winding of the third transformer form a star connection structure; the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are electrically connected together, so that the secondary winding of the first transformer, the secondary winding of the second transformer and the secondary winding of the third transformer form a star connection structure.

3. The multi-phase switching power supply conversion circuit according to claim 1, characterized in that: The first end of the primary winding of the first transformer, the first end of the primary winding of the second transformer, the first end of the primary winding of the third transformer, the first end of the secondary winding of the first transformer, the first end of the secondary winding of the second transformer and the first end of the secondary winding of the third transformer are the same-named ends; the second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer, the second end of the primary winding of the third transformer, the second end of the secondary winding of the first transformer, the second end of the secondary winding of the second transformer and the second end of the secondary winding of the third transformer are the same-named ends; The second end of the primary winding of the first transformer, the second end of the primary winding of the second transformer and the second end of the primary winding of the third transformer are electrically connected together, so that the primary winding of the first transformer, the primary winding of the second transformer and the primary winding of the third transformer form a star connection structure; the second end of the secondary winding of the first transformer is electrically connected to the first end of the secondary winding of the second transformer, the second end of the secondary winding of the second transformer is electrically connected to the first end of the secondary winding of the third transformer, and the second end of the secondary winding of the third transformer is electrically connected to the first end of the secondary winding of the first transformer, so that the secondary winding of the first transformer, the secondary winding of the second transformer and the secondary winding of the third transformer form a triangle connection structure.

4. The multi-phase switching power supply conversion circuit according to claim 1, characterized in that: A second switch circuit, a fourth resonant circuit, a fifth resonant circuit and a sixth resonant circuit are also provided; The second switch circuit includes a fifth bridge arm, a sixth bridge arm, a seventh bridge arm and an eighth bridge arm; The fourth resonant circuit comprises a fourth inductor and a fourth capacitor connected in series, and the fourth resonant circuit is connected in series with the secondary winding of the first transformer and connected between the midpoint of the bridge arm of the sixth bridge arm and the midpoint of the bridge arm of the fifth bridge arm; The fifth resonant circuit comprises a fifth inductor and a fifth capacitor connected in series, and the fifth resonant circuit is connected in series with the secondary winding of the second transformer and connected between the midpoint of the seventh bridge arm and the midpoint of the fifth bridge arm; The sixth resonant circuit includes a sixth inductor and a sixth capacitor. The sixth resonant circuit is connected in series with the secondary winding of the third transformer and is connected between the midpoint of the eighth bridge arm and the midpoint of the fifth bridge arm.

5. A multi-phase switching power supply conversion circuit, characterized in that: include: A first switch circuit comprises a first bridge arm, a second bridge arm and a third bridge arm; Transformers, including a first transformer, a second transformer and a third transformer; A first resonant circuit comprises a first inductor and a first capacitor connected in series, wherein the first resonant circuit is connected in series with a primary winding of the first transformer; A second resonant circuit, comprising a second inductor and a second capacitor connected in series, wherein the second resonant circuit is connected in series with the primary winding of the second transformer; A third resonant circuit, comprising a third inductor and a third capacitor connected in series, wherein the third resonant circuit is connected in series with the primary winding of the third transformer; as well as The second switch circuit includes a fourth bridge arm, a fifth bridge arm, a sixth bridge arm and a seventh bridge arm; a fourth resonant circuit, comprising a fourth inductor and a fourth capacitor connected in series, wherein the fourth resonant circuit is connected in series with the secondary winding of the first transformer and connected between a midpoint of the fifth bridge arm and a midpoint of the fourth bridge arm; a fifth resonant circuit, comprising a fifth inductor and a fifth capacitor connected in series, wherein the fifth resonant circuit is connected in series with the secondary winding of the second transformer and connected between a midpoint of the sixth bridge arm and a midpoint of the fourth bridge arm; The sixth resonant circuit comprises a sixth inductor and a sixth capacitor connected in series. The sixth resonant circuit is connected in series with the secondary winding of the third transformer and then connected between the midpoint of the seventh bridge arm and the midpoint of the fourth bridge arm.

6. A control method for the multi-phase switching power supply conversion circuit according to claim 1, characterized in that: include: When the multi-phase switching power supply conversion circuit is in a light load or no-load state, the lower switch tube in the fourth bridge arm works, and the upper switch tube in the fourth bridge arm does not work, only one of the first, second, and third bridge arms works, and the driving pulse of the upper switch tube and the driving pulse of the lower switch tube of the bridge arm in the working state among the first, second, and third bridge arms are complementary, the driving pulse of the lower switch tube in the fourth bridge arm is the same as the driving pulse of the upper switch tube of the bridge arm in the working state among the first, second, and third bridge arms, or the lower switch tube in the fourth bridge arm remains in a normally open state.

7. A control method for the multi-phase switching power supply conversion circuit according to claim 1, characterized in that: include: When the multi-phase switching power supply conversion circuit is in a light load or no-load state, the upper switch tube in the fourth bridge arm is working, and the lower switch tube in the fourth bridge arm is not working. Only the lower switch tube in one of the first, second and third bridge arms is working, and the driving pulse of the lower switch tube in the first, second and third bridge arms that is in working state is the same as the driving pulse of the upper switch tube in the fourth bridge arm.

8. A control method for the multi-phase switching power supply conversion circuit according to claim 1, characterized in that: include: When the multi-phase switching power supply conversion circuit is in a light load or no-load state, the fourth bridge arm is working, and only one of the first, second and third bridge arms is working, and the bridge arm in the working state among the first, second and third bridge arms, the driving pulse of the upper switch tube and the driving pulse of the lower switch tube are complementary, the driving pulse of the upper switch tube is the same as the driving pulse of the lower switch tube in the fourth bridge arm, and the driving pulse of the lower switch tube is the same as the driving pulse of the upper switch tube in the fourth bridge arm.

9. The control method according to any one of claims 6 to 8, characterized in that: When the multi-phase switching power supply conversion circuit is in a full load or heavy load state, the driving pulse phases of the upper switch tube in the first bridge arm, the upper switch tube in the second bridge arm, and the upper switch tube in the third bridge arm are 120° apart in sequence; the driving pulse phases of the lower switch tube in the first bridge arm, the lower switch tube in the second bridge arm, and the lower switch tube in the third bridge arm are 120° apart in sequence; When the multi-phase switching power supply conversion circuit is in a half-load state, any two of the first, second, and third bridge arms are in operation, and the driving pulse phases of the upper switch tube in one of the bridge arms in operation and the upper switch tube in the other bridge arm in operation differ by 180°, and the driving pulse phases of the lower switch tube in one of the bridge arms and the lower switch tube in the other bridge arm differ by 180°.

10. The control method according to claim 9, characterized in that: The driving pulses of the upper switch tube and the lower switch tube in the first bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time; the driving pulses of the upper switch tube and the lower switch in the second bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time; the driving pulses of the upper switch tube and the lower switch tube in the third bridge arm are complementary, and the duty cycle is 50% after ignoring the dead time.

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