Novel AC / DC converter based on resonant transformation

Abstract

The invention provides a novel AC / DC converter based on resonant transformation, which relates to the technical field of modern switching power supplies, and comprises an input-stage topological structure, the input-stage topological structure is connected with a resonant cavity, the resonant cavity is connected with the primary side of a high-frequency transformer, and the secondary side of the high-frequency transformer is connected with an output-stage topological structure; the input-stage topological structure is a half-bridge structure or an opposite full-bridge structure, power frequency sinusoidal voltage is converted by the input-stage topological structure to obtain a high-frequency pulse type input signal, a high-frequency alternating-current square wave signal is obtained at the primary side of the high-frequency transformer through the resonant cavity, and the high-frequency alternating-current square wave signal is boosted or depressurized through the high-frequency transformer. And the secondary side of the high-frequency transformer is rectified through an output-stage topological structure to obtain a direct-current output voltage. According to the invention, under the condition that the driving signal of the topological switch tube is relatively simple, a relatively good conversion effect is achieved, the voltage stress of the switch tube is small, meanwhile, the conversion stage number is reduced, the energy transfer path is reduced, the system operation efficiency can be improved, the power density of the system is improved, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of modern switching power supply technology, and in particular to a novel AC / DC converter based on resonant transformation. Background Technology

[0002] In modern switching power supplies, high efficiency, low electromagnetic interference (EMI), and high power density are the core development directions for power supply design. Traditional PWM (Pulse Width Modulation) hard-switching converters have certain limitations in medium- and high-power applications: their switching transistors are subjected to large voltage and current stresses under high-frequency operating conditions, resulting in a significant increase in switching losses. At the same time, the large dv / dt and di / dt of the devices can also easily cause EMI problems, which is not conducive to meeting the system's requirements for energy efficiency and electromagnetic compatibility.

[0003] To address these issues, academia and industry have gradually introduced soft-switching resonant converter technology. Among them, LLC resonant converters are widely used in AC / DC power adapters, server power supplies, communication power supplies, and automotive power systems due to their superior performance.

[0004] In existing AC / DC power supply systems, common solutions typically employ a multi-stage energy conversion structure. The input power frequency AC power first passes through a rectifier circuit to form a stable high-voltage DC bus, and then undergoes voltage conversion and isolation via an LLC resonant converter or other isolated topology. Although this type of architecture can meet the basic requirements of power conversion, it still has the following shortcomings: 1. The circuit has many transformation stages and a long energy transfer path. The input AC power goes through multiple energy transformation stages such as rectification, inversion, resonant transformation and secondary side rectification and filtering. Each stage of the circuit introduces a certain amount of energy loss, which limits the overall efficiency. 2. The large number of components results in significant system cost and size. Multi-level topologies require numerous switching devices, magnetic components, and control circuits, increasing hardware complexity and system cost, and also posing challenges to power density. 3. Limited efficiency, especially under light load or wide input conditions, multi-stage energy conversion leads to large cumulative losses, and the efficiency drop is more significant under light load conditions, which is not conducive to meeting modern high energy efficiency standards. 4. The control strategy is complex, which affects the reliability of the system. Multi-stage circuits need to be coordinated and controlled, such as the dynamic interaction between the inverter circuit and the LLC stage, as well as the coordination between frequency regulation and synchronous rectification. This increases the complexity of the control algorithm and places higher demands on the performance and reliability of the controller. 5. Slow dynamic response: When the load changes suddenly or the input voltage fluctuates, the multi-stage structure often has inter-stage coupling effect, which limits the system response speed and results in insufficient transient stability of the output voltage. In summary, while traditional AC / DC power converters have been widely used in server power supplies, adapters, and automotive power supplies, their shortcomings in structural complexity, energy efficiency, and system reliability have become a major driving force for research into novel, high-efficiency topologies. Therefore, designing a novel AC / DC converter based on resonant transformation is essential. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a novel AC / DC converter based on resonant transformation.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a novel AC / DC converter based on resonant transformation, comprising: a high-frequency transformer, a resonant cavity, an input stage topology, and an output stage topology. The input stage topology is connected to the resonant cavity, the resonant cavity is connected to the primary side of the high-frequency transformer, and the secondary side of the high-frequency transformer is connected to the output stage topology. The input stage topology is a half-bridge structure or a top-down full-bridge structure. The power frequency sinusoidal voltage is transformed by the input stage topology to obtain a high-frequency pulsed input signal. This signal is then passed through a resonant cavity to the primary side of a high-frequency transformer to obtain a high-frequency AC square wave signal. After being stepped up or stepped down by the high-frequency transformer, the signal is rectified by the output stage topology on the secondary side of the high-frequency transformer to obtain a DC output voltage.

[0007] Preferably, the input stage topology includes a power supply, a first bidirectional high-frequency switching unit, and a second bidirectional high-frequency switching unit. The positive terminal of the power supply is connected to the first bidirectional high-frequency switching unit, the first bidirectional high-frequency switching unit is connected to the resonant cavity and the second bidirectional high-frequency switching unit, the second bidirectional high-frequency switching unit is connected to the negative terminal of the power supply, the resonant cavity is connected to the primary side of the high-frequency transformer, and the primary side of the high-frequency transformer is connected to the negative terminal of the power supply.

[0008] Preferably, the first bidirectional high-frequency switching unit and the second bidirectional high-frequency switching unit have the same structure.

[0009] Preferably, the first bidirectional high-frequency switching unit includes a first IGBT switch T1, a second IGBT switch T2, and diodes D3 and D4 corresponding to the first IGBT switch T1 and the second IGBT switch T2, respectively. The power supply is connected to the collector of the first IGBT switch T1, the emitter of the first IGBT switch T1 is connected to the emitter of the second IGBT switch T2, the collector of the second IGBT switch T2 is connected to the second bidirectional high-frequency switching unit, and diodes D3 and D4 are connected in parallel between the emitters and collectors of the first IGBT switch T1 and the second IGBT switch T2, respectively.

[0010] Preferably, the resonant cavity is an LLC resonant cavity, including a capacitor Cr and an inductor Lr. The collector of the second IGBT switch T2 is connected to the capacitor Cr, the capacitor Cr is connected to the inductor Lr, and the inductor Lr is connected to the primary side of the high-frequency transformer.

[0011] Preferably, the resonant cavity is an LCC resonant cavity.

[0012] Preferably, the output stage topology is a full-wave rectifier circuit.

[0013] Preferably, the output stage topology includes diode D1, diode D2, capacitor C, and resistor R. The positive and negative terminals of the secondary winding of the high-frequency transformer are connected to the positive terminals of diode D1 and diode D2, respectively. The negative terminals of diode D1 and diode D2 are connected to capacitor C and resistor R. Capacitor C and resistor R are connected to the middle of the secondary winding of the high-frequency transformer.

[0014] Preferably, the output stage topology is a full-bridge rectifier circuit.

[0015] Preferably, the transformer is a single-input, single-output transformer without a center tap.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention provides a novel AC / DC converter based on resonant transformation, comprising a high-frequency transformer, a resonant cavity, an input stage topology, and an output stage topology. The input stage topology is connected to the resonant cavity, which is connected to the primary side of the high-frequency transformer. The secondary side of the high-frequency transformer is connected to the output stage topology. The input stage topology is a half-bridge structure. The power frequency sinusoidal voltage is transformed by the input stage topology to obtain a high-frequency pulsed input signal. This signal is then passed through the resonant cavity to the primary side of the high-frequency transformer to obtain a high-frequency AC square wave signal. After being stepped up or stepped down by the high-frequency transformer, the signal is rectified by the output stage topology on the secondary side of the high-frequency transformer to obtain a DC output voltage. Compared to traditional multi-stage AC / DC converters, this invention proposes a novel topology consisting only of a half-bridge converter, a resonant cavity, a high-frequency transformer, and a subsequent rectifier circuit. This results in a simpler structure. The front-end employs a top-down half-bridge structure composed of four power switches, avoiding the multiple energy transfer processes of the traditional "rectification-bus-inverter" cycle. This reduces the number of switching devices, lowering system hardware costs and size. In terms of control, only phase and frequency modulation of the half-bridge switches is needed to achieve input power regulation and output voltage stabilization, significantly reducing control loops and simplifying logic. This improves system reliability and stability. Furthermore, the shortened energy transmission path reduces conduction and magnetic component losses. Combined with the soft-switching characteristics of the resonant cavity, this effectively reduces switching losses and significantly improves overall efficiency. In addition, this topology reduces voltage stress on the switching transistors and decreases the number of high-frequency switching actions, thereby suppressing harmonic components and improving electromagnetic compatibility. By reducing the number of energy conversion stages and energy transfer links, this invention not only improves power density and energy efficiency but also extends device lifespan, making it particularly suitable for AC / DC power supply applications with stringent requirements for high efficiency and high power density. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the topology of a traditional LLC scheme; Figure 2 This is a schematic diagram of a common LLC gain curve; Figure 3 This is a schematic diagram of the novel AC / DC converter based on resonant transformation according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a novel AC / DC converter topology based on resonant transformation according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the operating frequency range of a novel AC / DC converter based on resonant transformation according to an embodiment of the present invention; Figure 6 This is a schematic diagram of working mode 1; Figure 7 This is a schematic diagram of working mode 2; Figure 8 This is a schematic diagram of working mode 3; Figure 9 This is a schematic diagram of working mode 4; Figure 10 This is a schematic diagram of the resonant cavity current and the primary voltage of the transformer during the positive half-cycle. Figure 11 This is a schematic diagram of the input-level topology as a full-bridge AC / AC transform. Figure 12 The output stage topology is shown in the schematic diagram of a full-bridge uncontrolled rectifier. Figure 13 This is a schematic diagram of a three-phase AC / DC topology; Figure 14 This is a schematic diagram of a special example circuit of the present invention. Detailed Implementation

[0019] 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 embodiments of the present invention, and not all embodiments. 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.

[0020] The purpose of this invention is to provide a novel AC / DC converter based on resonant transformation, which has good conversion performance with relatively simple topology switching transistor drive signals, low switching transistor voltage stress, and at the same time, reduces the number of conversion stages, reduces energy transfer paths, improves system operating efficiency, increases system power density, and improves overall efficiency.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] First, let's introduce the LLC resonant converter. The LLC resonant converter consists of a series resonant inductor L. r Parallel excitation magnetizing inductor L m Composed of a resonant capacitor Cr, it can achieve the following advantages over a wide load range: High efficiency characteristics: The LLC topology can achieve zero voltage turn-on (ZVS) when the switch is turned on and zero current turn-off (ZCS) during the reverse recovery process of the freewheeling diode, thereby significantly reducing switching losses. The energy transfer characteristics of the resonant cavity enable the switching device to maintain low switching stress at high frequencies, which is beneficial to improving overall energy efficiency. Excellent EMI performance: The soft-switching characteristics reduce transient changes in current and voltage, and reduce dv / dt and di / dt, thereby reducing electromagnetic interference. Compared with hard-switching PWM, it can meet relevant standards without excessive reliance on EMI filtering devices. Wide input voltage and load adaptability: Through the design of the resonant frequency point and the magnetizing inductor, the LLC resonant converter can maintain high efficiency under conditions of wide input voltage fluctuation and load range. Under light load conditions, the switching frequency can be reduced by frequency conversion control, thereby suppressing no-load loss and meeting modern energy-saving requirements. High power density and modular design: LLC converters can operate efficiently at high frequencies of hundreds of kHz, which helps to reduce the size of magnetic and filter components and achieve higher power density. Its topology is suitable for integration with synchronous rectification and secondary-side rectification control to further improve system performance. Based on the above advantages, LLC resonant AC / DC converters have gradually become the mainstream choice for high-efficiency power supply systems, especially suitable for applications with high requirements for energy efficiency, power density and electromagnetic compatibility. In existing technologies, traditional AC / DC power converters generally employ an LLC resonant full-bridge topology as the isolated high-frequency conversion stage. The input of this type of circuit is typically a mains frequency AC voltage (such as 220V / 50Hz or 110V / 60Hz), which is first converted to a stable high-voltage DC bus voltage by a rectifier circuit. Then, the LLC resonant converter achieves high-frequency isolation and voltage conversion. Its topology is as follows: Figure 1 As shown; A typical LLC resonant AC / DC converter mainly includes the following components: Input stage: The mains frequency sinusoidal AC power supply is rectified and outputs approximately 310V DC high voltage bus; Intermediate stage resonant cavity: The resonant network consists of a series resonant inductor L r Resonant capacitor C r and transformer magnetizing inductance L m Together, they form a resonant cavity driven by a high-voltage DC power supply via a full-bridge or half-bridge switching network, enabling the resonant transfer of energy. High-frequency transformer: responsible for electrical isolation and voltage transformation, coupling the resonant energy of the primary side to the secondary side; Output stage: The secondary side typically uses diode rectification or synchronous rectification to convert high-frequency AC into DC voltage. After passing through the filter circuit, a stable DC output is provided to the load. In this traditional architecture, the LLC resonant circuit can achieve zero-voltage turn-on (ZVS) of the switching devices and zero-current turn-off (ZCS) of the freewheeling diode, thereby reducing switching losses and improving electromagnetic compatibility characteristics; this topology has been widely used in server power supplies, adapters and automotive power supplies. In the existing technology, the voltage gain characteristic of LLC resonant converter is one of its core design parameters. This topology forms a resonant network through series resonant inductor, resonant capacitor and transformer magnetizing inductor. The transfer characteristics between its output voltage and input voltage are closely related to the operating frequency, load conditions and resonant component parameters. Typically, the gain curve of an LLC resonant converter exhibits the following characteristics: Near the resonant frequency, the circuit can achieve near unity gain and has the highest efficiency. When the operating frequency is lower than the resonant frequency, the converter exhibits gain enhancement characteristics, which can maintain output stability when the input voltage is low. When the operating frequency is higher than the resonant frequency, the gain is less than 1, which is suitable for adjustment under conditions of increased input voltage or light load, thereby suppressing excessively high output voltage; This gain characteristic—greater than 1 at low frequencies, less than 1 at high frequencies, and close to 1 at the midpoint—allows LLC resonant converters to achieve regulated output within a certain range through frequency conversion control, while also ensuring adaptability to a wide input voltage range. Common LLC gain curves are shown below. Figure 2 As shown.

[0023] This invention designs a novel topology for traditional multi-stage converter structures, such as... Figure 3 and Figure 4 As shown, this invention provides a novel AC / DC converter based on resonant transformation, comprising: A high-frequency transformer, a resonant cavity, an input stage topology, and an output stage topology are provided. The input stage topology is connected to the resonant cavity, the resonant cavity is connected to the primary side of the high-frequency transformer, and the secondary side of the high-frequency transformer is connected to the output stage topology. The input stage topology is a half-bridge structure or a top-down full-bridge structure. The power frequency sinusoidal voltage is transformed by the input stage topology to obtain a high-frequency pulsed input signal. The signal is then passed through the resonant cavity to obtain a high-frequency AC square wave signal on the primary side of the high-frequency transformer. After being stepped up or stepped down by the high-frequency transformer, the signal is rectified on the secondary side of the high-frequency transformer through the output stage topology to obtain a DC output voltage. The input stage topology includes a power supply, a first bidirectional high-frequency switching unit, and a second bidirectional high-frequency switching unit. The positive terminal of the power supply is connected to the first bidirectional high-frequency switching unit. The first bidirectional high-frequency switching unit is connected to the resonant cavity and the second bidirectional high-frequency switching unit. The second bidirectional high-frequency switching unit is connected to the negative terminal of the power supply. The resonant cavity is connected to the primary side of the high-frequency transformer. The primary side of the high-frequency transformer is connected to the negative terminal of the power supply. The first bidirectional high-frequency switching unit and the second bidirectional high-frequency switching unit have the same structure. The first bidirectional high-frequency switching unit includes a first IGBT switch T1, a second IGBT switch T2, and diodes D3 and D4 corresponding to the first IGBT switch T1 and the second IGBT switch T2, respectively. The power supply is connected to the collector of the first IGBT switch T1, the emitter of the first IGBT switch T1 is connected to the emitter of the second IGBT switch T2, the collector of the second IGBT switch T2 is connected to the second bidirectional high-frequency switching unit, and diodes D3 and D4 are connected in parallel between the emitter and collector of the first IGBT switch T1 and the second IGBT switch T2, respectively. When the input stage topology adopts a top-down full-bridge structure, the full bridge can be directly formed by four sets of top-down switches. The full-bridge topology can directly transform the power frequency AC square wave signal into a high-frequency AC signal with a sinusoidal envelope and output it at the midpoint of the two bridge arms. The resonant cavity is an LLC resonant cavity, including capacitor C. r and inductor L r The collector of the second IGBT switch T2 is connected to the capacitor C. r The capacitor C r Connect the inductor L r The inductor L r Connect the primary side of the high-frequency transformer; The output stage topology is a full-wave rectifier circuit. The output stage topology includes diode D1, diode D2, capacitor C, and resistor R. The positive and negative terminals of the secondary coil of the high-frequency transformer are connected to the positive terminals of diode D1 and diode D2, respectively. The negative terminals of diode D1 and diode D2 are connected to capacitor C and resistor R. Capacitor C and resistor R are connected to the middle of the secondary coil of the high-frequency transformer. It should be noted that this embodiment of the invention uses IGBT switching transistors, but this does not mean that only IGBTs can be used. The secondary side of the topology transformer uses a full-wave rectifier circuit for operating mode analysis, but other common rectifier topologies such as full-bridge rectification can also be used. The transformer can be changed to a single-input single-output transformer without a center tap. The AC / AC converter on the primary side of the transformer also uses a full-bridge topology. The resonant circuit can also use other topologies such as LCC resonant circuits. Other embodiments will be introduced later. Here, the working model of the above structure will be analyzed in detail: When a sinusoidal voltage signal of power frequency is input to the AC side, the working mode of the proposed topology is analyzed taking the positive half-cycle as an example. Since the equivalent input signal of the LLC resonant cavity is a high-frequency pulse signal enveloped by the input signal, its amplitude changes with the input signal. In order to ensure that the output voltage is constant, frequency conversion control is selected in terms of control strategy. The gain of the LLC resonant cavity is changed with the amplitude of the input signal. That is, when the amplitude of the input voltage signal increases, the resonant cavity gain is reduced, and when the amplitude of the input voltage signal decreases, the resonant cavity gain is increased. A constant high-frequency AC square wave is obtained on the transformer input side. As can be seen from the gain curve of the LLC resonant converter, there exists a point of maximum gain when the switching frequency is less than the resonant frequency. The operating frequency of the switching transistor at this point is defined as f. min Since AC / DC converters often operate in boost mode, the LLC resonant cavity is determined to operate within a gain range greater than 1. When the switching frequency equals the resonant frequency, the resonant cavity gain is 1, and the operating frequency of the switching transistor at this time is defined as f. max That is, in the LLC gain curve, the operating frequency range of the switching transistor is as follows: Figure 5 As shown; As mentioned above, when the input voltage signal is near the zero-crossing point, the switching transistor maintains its minimum operating frequency f. min Because the AC / DC converter transfers almost no energy near the zero-crossing point, as the input voltage amplitude decreases, the operating voltage of the switching transistor gradually decreases to f. min From that time onwards, the switching transistors will operate at this frequency. During the positive half-cycle of the input power frequency AC voltage, the converter exhibits four operating modes, which are analyzed as follows: Operating Mode 1: When the upper arm's IGBT switch tubes (the first IGBT switch tube T1 and the second IGBT switch tube T2, which are in opposite directions) are turned on, and the lower arm's IGBT switch tubes (the third IGBT switch tube T3 and the fourth IGBT switch tube T4, which are in opposite directions) are turned off, the topology operating mode is as follows: Figure 6 As shown, at this time, the input power supply supplies power to the LLC resonant cavity, and the capacitor C... r With inductor L r When energy is released, the current flows in the resonant cavity as follows: Figure 6As shown, the current gradually decreases to 0, and the capacitance C... r The voltage across the two ends is positive on the left and negative on the right. After passing through the resonant cavity, the voltage on the primary side of the transformer is positive at the bottom and negative at the top. That is, under this working mode, the transformer is in a demagnetized state. At this time, the secondary diode D2 of the transformer is turned on. When the current in the resonant cavity decreases to 0 in the reverse direction, it enters working mode 2. Operating mode 2: When the upper arm is open to the jacking pipe and the lower arm is closed to the jacking pipe, the topology operating mode is as follows: Figure 7 As shown, at this time, the input power supply supplies power to the LLC resonant cavity, and the capacitor C... r With inductor L r Energy is stored, and the current flows in the resonant cavity as follows: Figure 7 As shown, the current gradually increases, and the capacitance C... r The voltage across the two ends is positive on the left and negative on the right. After passing through the resonant cavity, the voltage on the primary side of the transformer is positive on top and negative on the bottom. That is, under this working mode, the transformer is in an excited state. At this time, the secondary diode D1 of the transformer is turned on. When the working state of the switching transistor changes, the current in the resonant cavity increases to its maximum value in the positive direction and enters working mode 3. Operating mode 3: When the upper arm is off from the jacking pipe and the lower arm is on from the jacking pipe, the topology operating mode is as follows: Figure 8 As shown, at this time, the input power supply does not supply power to the LLC resonant cavity. Since the current direction cannot change abruptly, the capacitor C... r Continue to store energy, inductor L r Energy is released, at which point the capacitor C r With the voltage across the terminals being positive on the left and negative on the right, and the lower bridge arm conducting, the primary side of the transformer is connected to a series resonant capacitor C. r With inductor L r Clamping means that after passing through the resonant cavity, the primary voltage of the transformer is positive at the top and negative at the bottom. Under this working mode, the transformer is in an excited state. At this time, the secondary diode D1 of the transformer is turned on. When the resonant cavity current decreases to 0 in the positive direction, it enters working mode 4. Operating mode 4: When the upper arm is off from the jacking pipe and the lower arm is on from the jacking pipe, the topology operating mode is as follows: Figure 9 As shown, since the current inside the resonant cavity begins to increase in the reverse direction at this time, the capacitance C r Release energy, inductor L r Energy is stored, at which point the capacitor C r The voltage across the two ends is positive on the left and negative on the right. After passing through the resonant cavity, the voltage on the primary side of the transformer is positive at the bottom and negative at the top. Under this working mode, the transformer is in a demagnetized state. At this time, the diode D2 on the secondary side of the transformer is turned on. When the working state of the switching transistor changes, the current in the resonant cavity increases in the reverse direction to the maximum value. One cycle ends. After entering the next working cycle, the current in the resonant cavity decreases in the reverse direction. The waveforms of the resonant cavity current and the transformer primary voltage under the four operating modes are shown in the figure below. Figure 10As shown, during the negative half-cycle of the input power frequency voltage signal, the operating mode of the topology is similar to that of the positive half-cycle. Throughout the entire operation of the topology, by controlling the operating frequency of the switching transistor and changing the gain of the LLC resonant cavity, a high-frequency square wave AC signal with constant amplitude is approximately obtained on the input side of the transformer primary side, and the transformer secondary side rectifies and outputs a DC voltage.

[0024] This invention provides a topology diagram of an input-level topology with a full-bridge AC / AC transform. The remaining structures are unchanged from those described above. The specific structure is as follows: Figure 11 As shown; This invention also provides a schematic diagram of an output stage topology with full-bridge uncontrolled rectification. The remaining structures are not modified compared to the above structures, and the specific structure is as follows: Figure 12 As shown; This invention also provides a schematic diagram of a three-phase AC / DC topology, the specific structure of which is as follows: Figure 13 As shown; The above three embodiments are all derived from the technical solutions of this application.

[0025] The present invention also provides a special case, the circuit diagram of which is as follows: Figure 14 As shown, the subsequent stage is a switching transistor, which can realize bidirectional energy flow, i.e., DC / AC. Taking IGBT as an example, various switching transistors such as MOSFETs can be selected according to specific needs.

[0026] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0027] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A novel AC / DC converter based on resonant transformation, characterized in that, include: A high-frequency transformer, a resonant cavity, an input stage topology, and an output stage topology are provided. The input stage topology is connected to the resonant cavity, the resonant cavity is connected to the primary side of the high-frequency transformer, and the secondary side of the high-frequency transformer is connected to the output stage topology. The input stage topology is a half-bridge structure or a top-down full-bridge structure. The power frequency sinusoidal voltage is transformed by the input stage topology to obtain a high-frequency pulsed input signal. This signal is then passed through a resonant cavity to the primary side of a high-frequency transformer to obtain a high-frequency AC square wave signal. After being stepped up or stepped down by the high-frequency transformer, the signal is rectified by the output stage topology on the secondary side of the high-frequency transformer to obtain a DC output voltage.

2. The novel AC / DC converter based on resonant transformation according to claim 1, characterized in that, The input stage topology includes a power supply, a first bidirectional high-frequency switching unit, and a second bidirectional high-frequency switching unit. The positive terminal of the power supply is connected to the first bidirectional high-frequency switching unit. The first bidirectional high-frequency switching unit is connected to the resonant cavity and the second bidirectional high-frequency switching unit. The second bidirectional high-frequency switching unit is connected to the negative terminal of the power supply. The resonant cavity is connected to the primary side of the high-frequency transformer. The primary side of the high-frequency transformer is connected to the negative terminal of the power supply.

3. The novel AC / DC converter based on resonant transformation according to claim 2, characterized in that, The first bidirectional high-frequency switching unit and the second bidirectional high-frequency switching unit have the same structure.

4. The novel AC / DC converter based on resonant transformation according to claim 3, characterized in that, The first bidirectional high-frequency switching unit includes a first IGBT switch T1, a second IGBT switch T2, and diodes D3 and D4 corresponding to the first IGBT switch T1 and the second IGBT switch T2, respectively. The power supply is connected to the collector of the first IGBT switch T1, the emitter of the first IGBT switch T1 is connected to the emitter of the second IGBT switch T2, the collector of the second IGBT switch T2 is connected to the second bidirectional high-frequency switching unit, and diodes D3 and D4 are connected in parallel between the emitter and collector of the first IGBT switch T1 and the second IGBT switch T2, respectively.

5. The novel AC / DC converter based on resonant transformation according to claim 4, characterized in that, The resonant cavity is an LLC resonant cavity, including a capacitor Cr and an inductor Lr. The collector of the second IGBT switch T2 is connected to the capacitor Cr, the capacitor Cr is connected to the inductor Lr, and the inductor Lr is connected to the primary side of the high-frequency transformer.

6. The novel AC / DC converter based on resonant transformation according to claim 1, characterized in that, The resonant cavity is an LCC resonant cavity.

7. The novel AC / DC converter based on resonant transformation according to claim 4, characterized in that, The output stage topology is a full-wave rectifier circuit.

8. The novel AC / DC converter based on resonant transformation according to claim 6, characterized in that, The output stage topology includes diode D1, diode D2, capacitor C, and resistor R. The positive and negative terminals of the secondary coil of the high-frequency transformer are connected to the positive terminals of diode D1 and diode D2, respectively. The negative terminals of diode D1 and diode D2 are connected to capacitor C and resistor R. Capacitor C and resistor R are connected to the middle of the secondary coil of the high-frequency transformer.

9. The novel AC / DC converter based on resonant transformation according to claim 1, characterized in that, The output stage topology is a full-bridge rectifier circuit.

10. The novel AC / DC converter based on resonant transformation according to claim 1, characterized in that, The transformer is a single-input, single-output transformer without a center tap.

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