An isolated single-stage dc-dc converter based on integrated matrix magnetic core

Abstract

The application discloses an isolated single-stage DC-DC converter based on an integrated matrix magnetic core. The integrated matrix magnetic core is connected with an input end through a phase-shift full-bridge structure, and the phase-shift full-bridge structure is used for realizing zero-voltage turn-on of a primary side switch tube. The integrated matrix magnetic core is connected with an output end through a current doubling rectifier circuit with a resonance capacitor, and zero-current turn-off and zero-voltage turn-on of a synchronous rectifier tube are realized through resonance. The application realizes zero-voltage turn-on of the primary side switch tube, zero-voltage turn-on and zero-current turn-off of a secondary side synchronous rectifier tube, and improves energy conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to an isolated single-stage DC-DC converter based on an integrated matrix magnetic core. Background Technology

[0002] Power electronics technology is a crucial supporting technology for national security and people's lives. It is an important technological means to achieve energy conservation and environmental protection and improve people's quality of life. The extent to which power electronics technology is used is also an important indicator of a country's level of development. High-efficiency and high-power-density power conversion is the ultimate goal of power electronics technology development.

[0003] With the rapid development of artificial intelligence, big data, and cloud computing, the load demand of data centers is increasing year by year, and high-performance CPUs are developing towards lower voltage and higher current. Voltage regulators (VRMs), acting as a bridge between the bus voltage and the microprocessor's operating voltage, have their structural performance significantly limiting energy conversion efficiency and power density. Currently, 48V DC bus voltage is under development and has been applied in industrial fields. Many different topologies have been proposed to achieve DC-DC conversion from 48V to 1.xV for 48V bus voltage.

[0004] Currently, voltage regulators can be divided into two categories based on their topology:

[0005] (1) Two-stage topology: the first stage topology converts the high input voltage to the intermediate voltage (48V to 12V), and then the second stage converts the intermediate voltage to the low output voltage (12V to 1.xV);

[0006] (2) Single-stage topology, directly converting the bus voltage into the CPU's operating voltage.

[0007] For two-stage converters, there are many isolated and non-isolated topologies, which have been recognized by both industry and academia, but they all have significant drawbacks:

[0008] First, the use of transformers increases the size of the converter. Second, the overall efficiency of a two-stage converter is usually limited by the product of the efficiencies of the two stages, especially under light load and maximum load conditions, making it impossible to obtain a smooth efficiency curve. Considering the problems of two-stage topologies, isolated single-stage topologies have attracted the attention of researchers, with current-doubled rectifier converters on the secondary side being one of the most popular single-stage topologies. However, current-doubled rectifier converters contain one transformer and two inductors, and multi-phase converters are typically used in high-current output applications, which results in an excessive number of magnetic components in the circuit, reducing the converter's power density. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide an isolated single-stage DC-DC converter based on an integrated matrix magnetic core, which reduces the number of magnetic components and high-current connection points, in order to address the shortcomings of the prior art.

[0010] The present invention adopts the following technical solution:

[0011] An isolated single-stage DC-DC converter based on an integrated matrix core includes an integrated matrix core. The integrated matrix core is connected to the input terminal through a phase-shifted full-bridge structure, which is used to achieve zero-voltage turn-on of the primary-side switching transistor. The integrated matrix core is connected to the output terminal through a current-doubling rectifier circuit with a resonant capacitor, and the synchronous rectifier achieves zero-current turn-off and zero-voltage turn-on through resonance.

[0012] Specifically, the integrated matrix core includes four side posts and one center post. P1 / S1, P2 / S2, P3 / S3 and P4 / S4 are wound on the four side posts respectively. P1, P2, P3 and P4 are the primary windings, and S1, S2, S3 and S4 are the secondary windings.

[0013] Furthermore, the primary windings are connected in series.

[0014] Furthermore, the secondary windings are connected in parallel.

[0015] Furthermore, the winding consists of five layers: the first, second, fourth, and fifth layers are secondary windings, and the third layer is the primary winding.

[0016] Specifically, the integrated matrix core includes two base transformers and four output inductors. The two base transformers are connected in series, with one end connected to the midpoint of the primary-side switching transistors Q1 and Q2, and the other end connected to the midpoint of the primary-side switching transistors Q3 and Q4. The two output inductors in phase are connected in series and then connected in parallel to the secondary side of the transformers. Each output inductor is connected to a resonant capacitor and the corresponding secondary-side synchronous rectifier.

[0017] Furthermore, the four output inductors include L1, L2, L3, and L4, with one end of L1 and L2 connected to the output voltage v. o The connection is as follows: the other end of L1 is connected to the other end of L2 via resonant capacitor C1; one end of the secondary synchronous rectifier diodes R1 and R2 is grounded, and the other end is connected to L1 and L2 respectively; one end of L3 and L4 is connected to the output voltage V. o The other end of L3 is connected to the other end of L4 via the resonant capacitor C2. One end of the secondary synchronous rectifier diodes R3 and R4 is grounded, and the other end is connected to L3 and L4 respectively.

[0018] Furthermore, the output voltage v o A constant conduction time control method is adopted, with a constant phase shift angle T. shiftAs a constant on-time, the output voltage is adjusted to the reference value by changing the switching frequency.

[0019] Furthermore, when the primary-side switch Q1 is at t0, it conducts with zero voltage, and the primary-side switch Q4, secondary-side synchronous rectifiers R1, R2, R3 and R4 remain in the conducting state.

[0020] When the secondary winding currents i2 and i4 are zero at time t1, the secondary synchronous rectifier diodes R2 and R4 are turned off with zero current; the output inductors L1 and L3 are clamped at the output voltage v. o The resonance occurs between the primary leakage inductance, the output inductors L2 and L4, and the resonant capacitors C1 and C2.

[0021] At time t2, the primary-side switch Q4 is turned off, and the primary-side current i p The parallel capacitor of the primary-side switch Q4 is charged, and the parallel capacitor of the primary-side switch Q3 is discharged. When the parallel capacitor of the primary-side switch Q3 is discharged to zero, the parasitic diode of the primary-side switch Q3 is turned on.

[0022] At time t3, the primary-side switch Q3 is turned on with zero voltage, and the primary-side current i p Freewheeling is achieved through primary-side switches Q1 and Q3;

[0023] At time t4, the voltage v across the secondary synchronous rectifier diodes R2 and R4 is... R2 and v R4 When the voltage is zero, the secondary synchronous rectifier diodes R2 and R4 conduct with zero voltage, and the sum of the primary voltages of the two base transformers is zero.

[0024] The primary-side switch Q1 is turned off at time t5, and the primary-side current i p The parallel capacitor of the primary-side switch Q1 is charged, and the parallel capacitor of the primary-side switch Q2 is discharged. When the discharge of the parallel capacitor of the primary-side switch Q2 is zero, the parasitic diode of the primary-side switch Q2 is turned on, and the primary-side switch Q2 is turned on with zero voltage at time t6.

[0025] Furthermore, the primary winding current, secondary winding current, and equivalent output inductor current satisfy the following conditions:

[0026] i P =-i T1_P =i T2_P =-i T3_P =i T4_P

[0027] i x =i Lx -i Tx_S

[0028]

[0029] Where x represents 1, 2, 3, 4, and i P Let i be the primary current. Tx_P i is the primary current of the equivalent transformer. Lx i is the current of the equivalent inductance. Tx_S Let n be the secondary current of the equivalent transformer, and n be the turns ratio of the primary and secondary sides.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] This invention discloses an isolated single-stage DC-DC converter based on an integrated matrix magnetic core. Compared with the traditional current-doubling rectifier circuit using discrete magnetic components, this invention uses an integrated matrix magnetic core to improve the power density and efficiency of the converter. By employing a phase-shifted full-bridge and a current-doubling rectifier circuit with a resonant capacitor, the primary-side switching transistor achieves zero-voltage turn-on, and the secondary-side synchronous rectifier transistor achieves zero-current turn-off and zero-voltage turn-on, thereby reducing switching losses and further improving the converter efficiency.

[0032] Furthermore, the four side posts are wound with primary and secondary windings respectively, replacing the transformer and inductor in the discrete magnetic component scheme. At the same time, the primary and secondary windings are wound on the same side post to reduce the leakage inductance of the primary and secondary sides.

[0033] Furthermore, the primary winding uses Litz wire. Since the diameter of Litz wire is smaller than the skin depth, the skin effect can be ignored, thereby reducing the primary winding loss.

[0034] Furthermore, the secondary winding uses copper foil. Compared to PCB winding, the copper foil dissipates heat faster because the solder mask on the PCB prevents heat dissipation. Simultaneously, due to the large secondary current of the converter, using multiple layers of copper foil in parallel reduces winding resistance, thereby lowering winding losses.

[0035] Furthermore, by placing the primary winding in the middle of the secondary winding and using an interleaved winding method, the leakage inductance of the transformer is reduced, thereby reducing the spike pulses of the switching transistor.

[0036] Furthermore, integrating the two base transformers and four output inductors reduces the size of the magnetic components. Simultaneously, due to the large secondary current of the converter, the high-current connection points on the secondary side would generate significant losses. Integration reduces the number of high-current connection points, thereby reducing losses. Additionally, integrating the magnetic components by connecting the two base transformers in series is equivalent to integrating a two-phase converter, allowing the converter to handle larger currents.

[0037] Furthermore, by adding a resonant capacitor to the secondary-side current-doubling rectifier circuit, compared with the traditional current-doubling rectifier circuit, the leakage inductance of the primary side, the output inductance, and the resonant capacitor form a resonant circuit, thereby enabling the secondary-side synchronous rectifier tube to achieve zero-current turn-off and zero-voltage turn-on, reducing switching losses.

[0038] Furthermore, by adopting constant on-time control, the switching frequency of the converter under light load is reduced, the switching loss is decreased, thereby improving the light load efficiency. At the same time, constant on-time control has a fast transient response speed.

[0039] Furthermore, by controlling the turn-on and turn-off times of the switching transistors, zero-voltage turn-on of the primary-side switching transistors and zero-voltage turn-on and zero-current turn-off of the secondary-side synchronous rectifier transistors can be achieved.

[0040] Furthermore, by analyzing the relationship between the primary winding current, the secondary winding current, and the equivalent inductance current, it is helpful to design integrated magnetic components and converters that meet current requirements, so that the magnetic components and power devices can operate within a safe range.

[0041] In summary, this invention improves power density and efficiency, reduces the high current stress on the synchronous rectifier tube on the low-voltage side, and improves energy conversion efficiency.

[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0043] Figure 1 This is the circuit topology diagram of an isolated single-stage converter using an integrated matrix core;

[0044] Figure 2 The diagrams show the integrated matrix core structure and winding structure, where (a) shows the structure of the integrated matrix core and (b) shows the winding structure.

[0045] Figure 3 The diagram shows the typical operating waveforms of an isolated single-stage converter using integrated matrix magnets.

[0046] Figure 4 The diagram shows the operating modes of an isolated single-stage converter using an integrated matrix magnetic component, where (a) is state 1 [t0, t1], (b) is state 2 [t1, t2], (c) is state 3 [t2, t3], (d) is state 4 [t3, t4], (e) is state 5 [t4, t5], and (f) is state 6 [t5, t6].

[0047] Figure 5 This is the equivalent resonant circuit diagram. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0052] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0053] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0054] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0055] This invention provides an isolated single-stage DC-DC converter based on an integrated matrix magnetic core. Based on the basic theory of magnetic integration, a novel isolated single-stage DC-DC converter using an integrated matrix magnetic core is designed for voltage regulators (VRMs) from 48V to 1.xV, reducing the number of magnetic components and high-current connection points.

[0056] Please see Figure 1 This invention discloses an isolated single-stage DC-DC converter based on an integrated matrix magnetic core. The primary side of the isolated single-stage DC-DC converter with an integrated matrix magnetic core is a phase-shifted full-bridge structure, and the secondary side is a current-doubling rectifier circuit with a resonant capacitor. The phase-shifted full-bridge structure on the primary side can achieve zero-voltage turn-on of the primary-side switching transistors, and the secondary side achieves zero-current turn-off (ZCS) and zero-voltage turn-on (ZVS) of the synchronous rectifier transistors through resonance, thereby further reducing the converter losses.

[0057] The integrated matrix core integrates two basic transformers and four output inductors into a single core, consisting of four side posts and one center post. P1, P2, P3, and P4 are the primary windings, and S1, S2, S3, and S4 are the secondary windings. P1, P2, P3, P4, S1, S2, S3, and S4 are integrated into the same core to improve power density. P1 / S1, P2 / S2, P3 / S3, and P4 / S4 are wound on the four side posts respectively.

[0058] The number of turns in each primary winding is N. p The number of turns in the secondary winding is N s .

[0059] The primary winding uses Litz wire, and the windings are connected in series.

[0060] The secondary winding uses copper foil and consists of four layers of windings connected in parallel.

[0061] The first, second, fourth, and fifth layers are secondary windings, and the third layer is the primary winding.

[0062] Please see Figure 2 , Figure 2The structure of the integrated matrix core and its winding structure are shown separately. Since the integrated matrix core has a symmetrical structure, only the winding structure of one side column is shown.

[0063] Since the integrated matrix core integrates the transformer and inductor into a single core, the operation of the DC-DC converter will be affected by this integration. Therefore, the working principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0064] The waveform of an isolated single-stage converter using an integrated matrix core is as follows: Figure 3 As shown, the equivalent circuit diagram and operating mode are as follows: Figure 4 As shown.

[0065] Please see Figure 3 The typical operating waveforms of an isolated single-stage converter using an integrated matrix core, from top to bottom, are: the drive voltages of the primary-side switches (Q1, Q2, Q3, and Q4); the drive voltages of the secondary-side synchronous rectifiers (R1, R2, R3, and R4); and the voltage (V) of the secondary-side synchronous rectifiers. R1 v R2 v R3 and v R4 Secondary winding currents (i1, i2, i3 and i4).

[0066] Please see Figure 4 There are six operating modes in the positive half-cycle of the switching cycle. The operating mode of the negative half-cycle is the same as that of the positive half-cycle, so it is ignored here. Figure 4 In the diagram, L1, L2, L3, and L4 are the equivalent inductances of the integrated matrix core, and T1, T2, T3, and T4 are the equivalent transformers. The equivalent inductances and equivalent transformers will be analyzed independently. in and v o These are the input voltage and the output voltage, i p L represents the primary current. leak i1, i2, i3, and i4 are the leakage inductance of the primary winding, and i4 is the current in the four secondary windings. T1_S i T2_S i T3_S and i T4_S It is the secondary current of the equivalent transformer, i T1_P i T2_P i T3_P and i T4_P It is the primary current of the equivalent transformer, i L1 i L2 i L3 and i L4 It is the current of the equivalent inductance. R1, R2, R3, and R4 are the secondary-side synchronous rectifier diodes (SRs). R1 v R2 v R3 and vR4 It is the voltage across the secondary-side synchronous rectifier diodes SRs. C1 and C2 are resonant capacitors. R1, L1 and T1 are defined as the first phase, R2, L2 and T2 as the second phase, R3, L3 and T3 as the third phase, and R4, L4 and T4 as the fourth phase.

[0067] The secondary-side synchronous rectifier diodes SRs pass through the primary-side leakage inductance L leak The resonance between the resonant capacitor C1 (C2) and the equivalent inductance L1 (L2, L3, L4) of the integrated matrix core achieves ZCS and ZVS; the conduction time of Q1 and the conduction time of Q2 are complementary, and the ZVS of Q1 and Q2 is achieved through the dead time between Q1 and Q2.

[0068] Similarly, switching transistors Q3 and Q4 also achieve ZVS conduction, and the output voltage v o Constant conduction time (COT) control is adopted, with a constant phase shift angle T. shift This serves as the constant on-time. By changing the switching frequency, the output voltage is adjusted to the reference value. For example... Figure 3 As shown, the first and third phases have the same operating mode, and the second and fourth phases have the same operating mode. There is a 180-degree phase shift angle between the first (third) phase and the second (fourth) phase.

[0069] The operating modes of a DC-DC converter are briefly described below:

[0070] (1) State 1 [t0, t1]

[0071] Please see Figure 4 (a) At time t0, Q1 conducts with zero voltage, and at this time, Q4, R1, R2, R3, and R4 remain conducting. Figure 4 In (a), the current satisfies equation (1), as follows:

[0072] i P =-i T1_P =i T2_P =-i T3_P =i T4_P (1)

[0073] i x =i Lx -i Tx_S

[0074]

[0075] Where x represents 1, 2, 3, 4. The voltages on L1, L2, L3, and L4 are clamped at -V. o Therefore, the current i L1 i L2 i L3 and iL4 The leakage inductance L decreases linearly, and the sum of the primary-side voltages of T1, T2, T3, and T4 is zero. leak The voltage across the terminals is v in Primary current i p A linear increase leads to i T1_S and i T3_S Decrease, i T2_S and i T4_S Increase. i L1 The rate of decrease is less than i T1_S The rate of decrease is such that i1 increases linearly.

[0076] Similarly, i3 increases linearly, while i2 and i4 decrease linearly.

[0077] (2) State 2 [t1, t2]

[0078] Please see Figure 4 (b) When i2 and i4 are equal to zero at t1, R2 and R4 are turned off with zero current; the equivalent resonant circuit is as follows: Figure 5 As shown, L1 and L3 are clamped at v at this time. o The resonance occurs at the primary side leakage inductance L leak Between the secondary equivalent inductance L2 (L4) and the resonant capacitance C1 (C2). During this stage, energy is transferred from the input to the output.

[0079] (3) State 3 [t2, t3]

[0080] Please see Figure 4 (c) At time t2, Q4 is turned off, i p C q4 Charge and C q3 Discharge, the voltage at point B increases to v in With C q3 Discharge to zero, D3 turns on to achieve zero-voltage turn-on of Q3.

[0081] (4) State 4 [t3, t4]

[0082] Please see Figure 4 (d) Because D3 is conducting, the voltage of Q3 is clamped to zero, therefore Q3 conducts with zero voltage at time t3. During this stage, i p Continue streaming through Q1 and Q3.

[0083] (5) State 5 [t4, t5]

[0084] Please see Figure 4 (e), at time t4, v R2 and v R4When the voltage is zero, R2 and R4 conduct with zero voltage. Similar to state 1, the sum of the primary voltages of T1, T2, T3, and T4 is zero. Therefore, L leak The voltage across the terminals is zero, i p Basically unchanged, resulting in i T1_S i T2_S i T3_S and i T4_S Since the current remains essentially unchanged, i1, i2, i3, and i4 are only affected by the equivalent inductance current, and decrease linearly.

[0085] (6) State 6 [t5, t6]

[0086] Please see Figure 4 (f), Q1 is turned off at time t5, i p C q1 Charge and for C q2 Discharge, when C q2 When the discharge is zero, D2 turns on to achieve zero-voltage turn-on of Q2, and Q2 turns on at time t6.

[0087] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0088] This invention designs integrated magnetic component schemes and discrete magnetic component schemes respectively. By using 3D Maxwell simulation software, the area occupied by the magnetic components and the magnetic component loss under full load for the two schemes are obtained.

[0089] Table 1 shows the area occupied by the two schemes and the magnetic component loss at full load.

[0090]

[0091] Since the discrete magnetic component design includes two base transformers and four inductors, the total area of ​​the discrete magnetic components is 2170 mm². 2 The total magnetic loss is 7.7W. Therefore, when using the same power devices, the integrated matrix magnet has a smaller footprint and lower magnetic losses.

[0092] In summary, the isolated single-stage DC-DC converter based on an integrated matrix magnetic core of the present invention has the following characteristics:

[0093] (1) The integrated matrix magnetic component integrates two basic transformers and four output inductors into a single magnetic core, reducing the number of magnetic components and high-current connection points in the circuit, thereby improving power density and efficiency.

[0094] (2) An isolated single-stage DC-DC converter with integrated matrix magnetic components can provide high output current and reduce the high current stress of the synchronous rectifier tube on the low voltage side.

[0095] (3) The isolated single-stage DC-DC converter with integrated matrix magnetic components can realize zero voltage conduction of the primary-side switching transistor, zero voltage conduction and zero current turn-off of the secondary-side synchronous rectifier transistor, thereby improving energy conversion efficiency.

[0096] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. An isolated single-stage DC-DC converter based on an integrated matrix magnetic core, characterized in that, It includes an integrated matrix magnetic core, which is connected to the input terminal through a phase-shifted full-bridge structure. The phase-shifted full-bridge structure is used to achieve zero-voltage turn-on of the primary-side switching transistor. The integrated matrix magnetic core is connected to the output terminal through a current-doubling rectifier circuit with a resonant capacitor. Through resonance, the synchronous rectifier transistor achieves zero-current turn-off and zero-voltage turn-on. The integrated matrix core consists of four side pillars and one center pillar, with windings on the four side pillars respectively. P 1 / S 1. P 2 / S 2. P 3 / S 3 and P 4 / S 4, P 1, P 2, P 3 and P 4 is the primary winding. S 1, S 2, S 3 and S 4 is the secondary winding. The integrated matrix core integrates two basic transformers and four output inductors. The primary windings of the two basic transformers are connected in series, with one end connected to the primary switching transistor. Q 1 and Q Connect the midpoint of 2, and connect the other end to the primary switch transistor. Q 3 and Q The midpoint connection of 4; the two output inductors of the same phase are connected in series and then in parallel with the secondary side of the transformer. Each output inductor is connected to a resonant capacitor and the corresponding secondary synchronous rectifier diode. The four output inductors include L 1, L 2, L 3 and L 4, L 1 and L One end of 2 is connected to the output voltage. v o connect, L The other end of 1 is connected to a resonant capacitor. C 1 and L The other end of 2 is connected to the secondary synchronous rectifier tube. R 1 and R One end of 2 is grounded, and the other end is connected to... L 1 and L 2 connections; L 3 and L One end of 4 is connected to the output voltage. v o connect, L The other end of 3 is connected to a resonant capacitor. C 2 and L The other end of 4 is connected to the secondary synchronous rectifier tube. R 3 and R One end of 4 is grounded, and the other end is connected to... L 3 and L 4. Connections.

2. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 1, characterized in that, The primary windings are connected in series.

3. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 1, characterized in that, The secondary windings are connected in parallel.

4. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 2 or 3, characterized in that, The winding consists of five layers: the first, second, fourth, and fifth layers are secondary windings, and the third layer is the primary winding.

5. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 1, characterized in that, Output voltage v o A constant conduction time control method is adopted, with a constant phase shift angle. T shift As a constant on-time, the output voltage is adjusted to the reference value by changing the switching frequency.

6. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 1, characterized in that, When the primary-side switching transistor Q 1 in t At 0, zero voltage conduction occurs, and the primary-side switching transistor... Q 4. Secondary-side synchronous rectifier tube R 1, R 2, R 3 and R 4. Maintain the conduction state; When the secondary winding current i 2 and i 4 in t When 1 equals zero, the secondary side synchronous rectifier tube R 2 and R 4. Zero-current shutdown; output inductor L 1 and L 3 is clamped at the output voltage v o Resonance occurs in the primary leakage inductance and the output inductance. L 2. L 4 and resonant capacitor C 1. C Between 2; exist t At 2 o'clock, the primary-side switch transistor Q 4. Turn-off, primary current i p Primary-side switching transistor Q The parallel capacitor of 4 is charged, and the primary-side switching transistor is also charged. Q The parallel capacitor of 3 discharges when the primary-side switching transistor... Q When the parallel capacitor of 3 discharges to zero, the primary-side switching transistor... Q The parasitic diode of 3 is conducting; Primary-side switching transistor Q 3 in t At time 3, zero voltage conduction occurs, and the primary current... i p Through the primary-side switching transistor Q 1 and primary-side switching transistor Q 3. Continued streaming; t At time 4, the secondary side synchronous rectifier tube R 2 and R 4. Voltage across the terminals v R2 and v R4 When equal to zero, the secondary side synchronous rectifier tube R 2 and R 4. Zero-voltage conduction: the sum of the primary voltages of the two base transformers is zero. Primary-side switching transistor Q 1 in t Turning off at time 5, primary current i p Primary-side switching transistor Q The parallel capacitor of 1 is charged, and the primary-side switching transistor is also charged. Q The parallel capacitor of 2 discharges when the primary-side switch transistor... Q When the parallel capacitor of 2 discharges to zero, the primary-side switching transistor... Q The parasitic diode of transistor 2 is turned on, and the primary-side switching transistor is activated. Q 2 in t Zero voltage conduction occurs at time 6.

7. The isolated single-stage DC-DC converter based on an integrated matrix magnetic core according to claim 6, characterized in that, The primary winding current, secondary winding current, and equivalent output inductor current satisfy the following conditions: in, x Representing 1, 2, 3, 4, The primary current, This represents the primary current of the equivalent transformer. The current is the equivalent inductance. This is the secondary current of the equivalent transformer. This represents the turns ratio between the primary and secondary sides.

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