A single-stage high-frequency modulation isolated power conversion circuit and a circuit control method
By using a single-stage high-frequency modulation isolated power conversion circuit, and combining a three-phase AC voltage source and a high-frequency bridge arm modulation module, the high-frequency switching loss problem caused by two-stage high-frequency switching is solved, thereby improving the power conversion efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN KEHUA HENGSHENG TECH
- Filing Date
- 2023-10-12
- Publication Date
- 2026-07-21
AI Technical Summary
In existing power conversion circuits, the use of two-stage high-frequency switches leads to high high-frequency switching losses and reduced efficiency.
An isolated power conversion circuit employing single-stage high-frequency modulation combines a three-phase AC voltage source, a rectifier module, three sets of low-frequency bidirectional switches, and a high-frequency bridge arm modulation module. The low-frequency bidirectional switch connects one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module, and high-frequency modulation is performed using only a single-stage high-frequency bridge arm modulation module.
It effectively reduces high-frequency switching losses and improves power conversion efficiency.
Smart Images
Figure CN122437404A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power conversion technology, and in particular to a single-stage high-frequency modulation isolated power conversion circuit and circuit control method. Background Technology
[0002] Existing power conversion circuits are used in fields such as electric vehicles and home appliances. In power conversion circuits, alternating current is converted into direct current required by the load. These power conversion circuits are generally implemented using a two-stage isolated topology circuit. In this topology circuit, high-frequency modulation is achieved through two stages of high-frequency switches to realize the conversion of alternating current into direct current.
[0003] However, each stage of high-frequency switching generates corresponding high-frequency switching losses. Using two stages of high-frequency switching for high-frequency modulation can easily lead to significant high-frequency switching losses, resulting in reduced power conversion efficiency. Summary of the Invention
[0004] This application provides a single-stage high-frequency modulation isolated power conversion circuit and circuit control method, which effectively reduces high-frequency switching losses and improves power conversion efficiency.
[0005] This application provides a single-stage high-frequency modulation isolated power conversion circuit, characterized in that it includes: a three-phase AC voltage source, a rectifier module, three sets of low-frequency bidirectional switches, and a high-frequency bridge arm modulation module; the ports of the high-frequency bridge arm modulation module include: a DC positive terminal, a DC level midpoint, a DC negative terminal, and two high-frequency bridge arm midpoints; The rectifier module is used to rectify the three-phase AC current input from the three-phase AC voltage source; the first terminal of the rectifier module is connected to the DC negative terminal of the high-frequency bridge arm modulation module, and the second terminal of the rectifier module is connected to the DC positive terminal of the high-frequency bridge arm modulation module. The three-phase AC voltage source includes three-phase input terminals. The first terminals of the three sets of low-frequency bidirectional switches are respectively connected to the input terminals of different phases, and the second terminals of the three sets of low-frequency bidirectional switches are connected to the DC level midpoint of the high-frequency bridge arm modulation module. The midpoints of the two high-frequency bridge arms of the high-frequency bridge arm modulation module serve as circuit output ports. The high-frequency bridge arm modulation module is used to perform high-frequency modulation on the phase current of the DC positive terminal, the DC level midpoint, and the DC negative terminal of the high-frequency bridge arm modulation module, and output the high-frequency modulated current through the two midpoints of the high-frequency bridge arms.
[0006] Furthermore, the low-frequency bidirectional switch includes: a first low-frequency switching transistor and a second low-frequency switching transistor; The input terminal of the first low-frequency switch is connected to a phase input terminal, and the input terminal of the second low-frequency switch is connected to the midpoint of the DC level of the high-frequency bridge arm modulation module. The output terminal of the first low-frequency switch is connected to the output terminal of the second low-frequency switch.
[0007] Furthermore, the high-frequency bridge arm modulation module includes a half-bridge arm, which includes: a first switch, a second switch, a third switch, and a fourth switch. The first switch, the second switch, the third switch, and the fourth switch are connected in series; The input terminal of the first switch is the positive DC terminal of the half-bridge arm, and the output terminal of the fourth switch is the negative DC terminal of the half-bridge arm. The series connection between the second switch and the third switch is the midpoint of the DC level of the half-bridge arm; The series connection between the first and second switching transistors is the midpoint of the first high-frequency bridge arm of the half-bridge arm, and the series connection between the third and fourth switching transistors is the midpoint of the second high-frequency bridge arm of the half-bridge arm.
[0008] Furthermore, the resonant conversion module includes a resonant unit, a transformer, and a rectifier unit; The midpoint of the first high-frequency bridge arm of the half-bridge arm is connected to the midpoint of the second high-frequency bridge arm of the half-bridge arm via the resonant unit and the primary winding of the transformer. The secondary winding of the transformer is connected to the rectifier unit.
[0009] Furthermore, the high-frequency bridge arm modulation module includes one or more half-bridge arms.
[0010] Furthermore, the resonant conversion module includes a transformer; The transformer can be connected in series, in parallel, in a star or delta configuration.
[0011] Furthermore, when the phase line voltage of the target phase input terminal among the three-phase input terminals is the intermediate voltage value, the low-frequency bidirectional switch of the target phase input terminal is turned on.
[0012] This application embodiment also provides a circuit control method, which is used to control the power conversion circuit as described above, including: During the operation of the power conversion circuit, a set of low-frequency bidirectional switches is turned on by low-frequency drive, so that one phase input terminal is connected to the DC level midpoint of the high-frequency bridge arm modulation module in the power conversion circuit. The high-frequency bridge arm modulation module is driven to perform high-frequency modulation on the phase current of the DC positive terminal, the DC level midpoint, and the DC negative terminal of the high-frequency bridge arm modulation module.
[0013] As can be seen from the above technical solutions, the embodiments of this application have the following advantages: In this embodiment, the first terminals of the three sets of low-frequency bidirectional switches are connected to the input terminals of different phases, and the second terminals of the three sets of low-frequency bidirectional switches are connected to the DC level midpoint of the high-frequency bridge arm modulation module. During the operation of the power conversion circuit, a set of low-frequency bidirectional switches is turned on by low-frequency drive, connecting one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module. The high-frequency bridge arm modulation module has two high-frequency bridge arm midpoints. The high-frequency bridge arm modulation module is used to perform high-frequency modulation on the phase currents of its DC positive terminal, DC level midpoint, and DC negative terminal, and outputs the high-frequency modulated current through the two high-frequency bridge arm midpoints. By connecting one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module through the low-frequency bidirectional switches, power conversion can be achieved using only a single-stage high-frequency bridge arm modulation module. Compared to high-frequency modulation using two stages of high-frequency switches, this effectively reduces high-frequency switching losses and improves the efficiency of power conversion. Attached Figure Description
[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0015] Figure 1 This is a structural block diagram of a single-stage high-frequency modulation isolated power conversion circuit disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of the midpoint of a single high-frequency bridge arm disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the midpoint of another single high-frequency bridge arm disclosed in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of the midpoint of two high-frequency bridge arms disclosed in an embodiment of this application; Figure 5 This is a waveform diagram of a bus voltage disclosed in an embodiment of this application; Figure 6 This is a waveform diagram of the bus current and rectified output current disclosed in an embodiment of this application. Detailed Implementation
[0016] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.
[0017] In the description of the embodiments of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application 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. Therefore, they should not be construed as limitations on the embodiments of this application.
[0018] In the description of the embodiments of this application, 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 the embodiments of this application based on the specific circumstances.
[0019] Existing power conversion circuits generally employ a two-stage isolated topology, which uses two stages of high-frequency switches for high-frequency modulation to convert AC to DC. However, each stage of high-frequency switching generates corresponding high-frequency switching losses. Using two stages of high-frequency switches for high-frequency modulation easily leads to significant high-frequency switching losses, resulting in reduced power conversion efficiency. Therefore, this application provides a single-stage high-frequency modulation isolated power conversion circuit, which can effectively reduce high-frequency switching losses and improve power conversion efficiency. Figure 1 As shown: The isolated power conversion circuit in this embodiment includes: a three-phase AC voltage source, a rectifier module, three sets of low-frequency bidirectional switches, a high-frequency bridge arm modulation module, and a resonant conversion module; the ports of the high-frequency bridge arm modulation module include a DC positive terminal, a DC level midpoint, a DC negative terminal, and a high-frequency bridge arm midpoint.
[0020] A three-phase AC voltage source, Vabc, is used to input three-phase AC current, including phase A, phase B, and phase C current. Phase A does not necessarily represent any specific phase of the three phases; rather, it can refer to any one of the three phases. Phases A, B, and C are merely used to distinguish between the phases. This three-phase AC power source can be understood as the power grid.
[0021] The rectifier module is connected to a three-phase AC voltage source to rectify the three-phase AC current input from the source, converting AC to DC. The rectifier module can include diodes or active switching transistors; specific options are not limited here. The first terminal of the rectifier module is connected to the negative DC terminal of the high-frequency bridge arm modulation module, and the second terminal is connected to the positive DC terminal of the high-frequency bridge arm modulation module. This means the rectified DC current is directed to both the negative and positive DC terminals of the high-frequency modulation module.
[0022] The isolated power conversion circuit includes three sets of low-frequency bidirectional switches (set 1: Q1 and Q2, set 2: Q3 and Q4, set 3: Q5 and Q6). These low-frequency bidirectional switches are driven to conduct at the power frequency, i.e., they are in low-frequency switching operation mode. The three-phase AC voltage source includes three-phase input terminals (phase A, phase B, and phase C). The first terminals of the three sets of low-frequency bidirectional switches are connected to the input terminals of different phases, and the second terminals are connected to the DC level midpoint of the high-frequency bridge arm modulation module. During the operation of the power conversion circuit, one set of low-frequency bidirectional switches is driven to conduct at low frequency, connecting one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module. It can be understood that only one set of low-frequency bidirectional switches is conducting at any given time, while the other two sets are off.
[0023] It is understandable that the rectifier module and three sets of low-frequency bidirectional switches can form a DC bus midpoint selection network. The midpoint of this DC bus is the DC level midpoint of the high-frequency bridge arm modulation module, the positive terminal of the DC bus is the DC positive terminal of the high-frequency bridge arm modulation module, and the negative terminal of the DC bus is the DC negative terminal of the high-frequency bridge arm modulation module. Figure 5 As shown, both the positive and negative neutral point voltages of the DC bus are DC voltages with low-frequency fluctuations. The low-frequency bidirectional switch, operating at power frequency, connects the neutral point of the DC bus to one phase input terminal, and then performs high-frequency modulation via a high-frequency bridge arm modulation module for power factor correction.
[0024] The isolated power conversion circuit includes a high-frequency bridge arm modulation module, which can be understood as a power factor correction (PFC) circuit. The high-frequency bridge arm modulation module is used to perform high-frequency modulation on the phase currents of its DC positive, DC midpoint, and DC negative terminals. The modulated three-phase sinusoidal currents are then rectified and output through a resonant converter module. It can be understood that the low-frequency bidirectional switch only conducts one phase input terminal connected to the DC midpoint of the high-frequency bridge arm modulation module, while the other two phase input terminals are connected to the DC positive and DC negative terminals of the high-frequency bridge arm modulation module respectively through the rectifier module. In this way, the high-frequency bridge arm modulation module can use the current flowing through the low-frequency bidirectional switch in the conducting state to perform power factor correction, making the current follow the voltage; at this time, the current in phase A, phase B, or phase C is used for power factor correction; and, using the currents at the DC positive and DC negative terminals of the high-frequency bridge arm modulation module, power factor correction can be performed on the other two phases. It is understandable that this high-frequency bridge arm modulation module includes multiple high-frequency switches, which are driven by high-frequency pulse broadband modulation (high-frequency PWM) to perform power factor correction for each phase. That is, there is no need to use high-frequency switches in the bidirectional switch; power factor correction can be performed using only a single-stage high-frequency switch in the high-frequency bridge arm modulation module. Figure 6 As shown, by connecting one phase input terminal during operation, the positive current, negative current, and midpoint current of the DC bus are power factor corrected and low-frequency amplitude modulated through the high-frequency bridge arm modulation module, which can effectively reduce the low-frequency fluctuation of the rectified output current.
[0025] As can be seen, in this embodiment, the first terminals of the three sets of low-frequency bidirectional switches are connected to the input terminals of different phases, and the second terminals of the three sets of low-frequency bidirectional switches are connected to the DC level midpoint of the high-frequency bridge arm modulation module. During the operation of the power conversion circuit, a set of low-frequency bidirectional switches is turned on by low-frequency drive, connecting one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module. The high-frequency bridge arm midpoint of the high-frequency bridge arm modulation module is connected to the resonant conversion module. The high-frequency bridge arm modulation module is used to perform high-frequency modulation on the phase currents of its DC positive terminal, DC level midpoint, and DC negative terminal, and the high-frequency modulated three-phase sinusoidal current is rectified and output through the resonant conversion module. By connecting one phase input terminal to the DC level midpoint of the high-frequency bridge arm modulation module through a low-frequency bidirectional switch, power conversion can be achieved using only a single-stage high-frequency bridge arm modulation module. Compared to high-frequency modulation using two stages of high-frequency switches, this effectively reduces high-frequency switch losses and improves the efficiency of power conversion.
[0026] Furthermore, such as Figure 2As shown in the diagram, the black dots at the intersections of the lines indicate where the lines intersect. The rectifier unit can be a three-group diode half-bridge rectifier circuit (D1 and D2, D3 and D4, D5 and D6). This low-frequency bidirectional switch can include a first low-frequency switching transistor and a second low-frequency switching transistor; the low-frequency switching transistor can be a MOSFET or a transistor, which is not specifically limited here. A low-frequency switching transistor can also be obtained by connecting two or more MOSFETs or transistors in series. The input terminal of the first low-frequency switching transistor is connected to one phase input terminal, and the input terminal of the second low-frequency switching transistor is connected to the midpoint of the DC level of the high-frequency bridge arm modulation module; the output terminals of the first and second low-frequency switching transistors are connected.
[0027] When the phase line voltage of the target phase input terminal in the three-phase AC voltage source is at the intermediate voltage value, the low-frequency bidirectional switch of the target phase input terminal is turned on. It can be understood that during operation, the phase line voltages at the three-phase input terminals have a maximum voltage value, an intermediate voltage value, and a minimum voltage value. For example, the phase line voltage at phase A input terminal is the maximum voltage value, the phase line voltage at phase B input terminal is the intermediate voltage value, and the phase line voltage at phase C input terminal is the minimum voltage value. At this time, the current at phase A input terminal can be conducted through the rectifier unit to the DC positive terminal of the high-frequency bridge arm modulation module, and the current at phase C input terminal can be conducted through the rectifier unit to the DC negative terminal of the high-frequency bridge arm modulation module, controlling the low-frequency bidirectional switch corresponding to phase B input terminal to turn on, so that the current at phase B input terminal is conducted to the DC level midpoint of the high-frequency bridge arm modulation module. The high-frequency bridge arm modulation module performs high-frequency modulation on the currents at the DC positive terminal, DC negative terminal, and DC level midpoint to generate compensation current, ultimately combining to obtain a three-phase sinusoidal current.
[0028] The high-frequency bridge arm modulation module can be understood as a three-level full-bridge. The high-frequency bridge arm modulation module includes a half-bridge arm, which may include only one high-frequency bridge arm midpoint. Specifically, the half-bridge arm includes: a first switch Q7, a second switch Q8, a third switch Q9, a fourth switch Q10, a first diode D7, and a second diode D8; the first switch Q7, the second switch Q8, the third switch Q9, and the fourth switch Q10 are connected in series; the switching transistors of the half-bridge arm are high-frequency switching transistors, which can be MOSFETs or transistors, and are not specifically limited here. The input terminal of the first switch Q7 is the DC positive terminal of the half-bridge arm, and the output terminal of the fourth switch Q10 is the DC negative terminal of the half-bridge arm. The anode of the first diode D7 is connected to the anode of the second diode D8, and the connection point is the midpoint of the DC level of the half-bridge arm. The cathode of the first diode D7 is connected to the series line of the first switch D7 and the second diode D8, and the cathode of the second diode D8 is connected to the series line of the third switch D9 and the fourth switch D10. The series line of the second switch D8 and the third switch D9 is the midpoint of the high-frequency arm of the half-bridge arm. This half-bridge arm can perform high-frequency modulation on the three-phase current connected to the DC positive terminal, DC negative terminal, and DC level midpoint of the half-bridge arm to obtain the corresponding compensation current at the three-phase input terminals. The compensation currents at the three-phase input terminals are then combined to obtain a three-phase sinusoidal current for power factor correction.
[0029] The resonant converter module (LLC network) may include a resonant unit (inductor Lrn and capacitor Crn, n is a positive integer), a transformer (Tn, n is a positive integer), and a rectifier unit (multiple sets of rectifier diodes). The midpoint of the high-frequency arm of the half-bridge is connected to the primary winding of the transformer via the resonant unit; the secondary winding of the transformer is connected to the rectifier unit. That is, the current modulated at high frequency by the half-bridge arm is transmitted to the primary winding of the transformer, and then rectified and output through the secondary winding. This resonant converter module may include a filter capacitor (Con, n is a positive integer) for filtering the output.
[0030] It is understood that the high-frequency modulation module may include one or more half-bridge arms, and the transformer in this resonant converter module can be connected in series, parallel, star, or delta configurations. The wiring method can be chosen based on the number of half-bridge arms. For example... Figure 2As shown, the high-frequency modulation module includes two half-bridge arms (one half-bridge arm composed of Q7, Q8, Q9, Q10, D7, and D8, and another half-bridge arm composed of Q11, Q12, Q13, Q14, D9, and D10). The positive DC terminals of each half-bridge arm are connected, the midpoints of the DC levels are connected, and the negative DC terminals are connected. Each half-bridge arm includes a midpoint of a high-frequency arm, which is connected to the primary winding of the transformer. At this time, the resonant converter module has two transformers (T1 and T2), with their primary windings connected in series. The secondary winding of transformer T1 corresponds to rectifier diodes (D21, D22, D23, and D24), and the secondary winding of transformer T2 corresponds to rectifier diodes (D25, D26, D27, and D28), resulting in two sets of DC voltages. These two sets of DC voltages are combined in series and parallel through switches (S1, S2, and S3).
[0031] like Figure 3 As shown, the high-frequency modulation module includes three half-bridge arms (one half-bridge arm composed of Q7, Q8, Q9, Q10, D7, and D8; another half-bridge arm composed of Q11, Q12, Q13, Q14, D9, and D10; and yet another half-bridge arm composed of Q15, Q16, Q17, Q18, D11, and D12). Each half-bridge arm includes a high-frequency arm midpoint, which is connected to the primary winding of the transformer. In this case, the resonant converter module is a three-phase LLC network, including three transformers. The primary windings of the three transformers are connected in a star configuration, and the secondary windings of the three transformers are also connected in a star configuration. The secondary windings of the three transformers are connected to a three-phase diode bridge (D31, D32, D33, D34, D35, and D36), which rectifies to obtain a DC voltage.
[0032] Furthermore, such as Figure 4 As shown, the half-bridge arm may include the midpoints of two high-frequency bridge arms. The half-bridge arm includes: a first switch Q7, a second switch Q8, a third switch Q9, and a fourth switch Q10; the first switch Q7, the second switch Q8, the third switch Q9, and the fourth switch Q10 are connected in series; the input terminal of the first switch Q7 is the DC positive terminal of the half-bridge arm, and the output terminal of the fourth switch Q10 is the DC negative terminal of the half-bridge arm; the series connection between the second switch Q8 and the third switch Q9 is the midpoint of the DC level of the half-bridge arm; the series connection between the first switch Q7 and the second switch Q8 is the midpoint of the first high-frequency bridge arm of the half-bridge arm, and the series connection between the third switch Q9 and the fourth switch Q10 is the midpoint of the second high-frequency bridge arm of the half-bridge arm. This half-bridge arm can be understood as a cascaded half-bridge.
[0033] The two high-frequency arms of the half-bridge are connected to the resonant converter module. Specifically, the resonant converter module includes a resonant unit, a transformer, and a rectifier unit. The midpoint of the first high-frequency arm of the half-bridge is connected to the first end of the primary winding of the transformer via the resonant unit, and the midpoint of the second high-frequency arm of the half-bridge is connected to the second end of the primary winding of the transformer. The secondary winding of the transformer is connected to the rectifier unit.
[0034] It is understandable that the high-frequency bridge arm modulation module includes one or more half-bridge arms, and the transformer of the resonant converter module can be connected in series, parallel, star, or delta configurations. For example... Figure 4 As shown, the high-frequency modulation module includes three half-bridge arms (one half-bridge arm composed of Q7, Q8, Q9, and Q10; one half-bridge arm composed of Q11, Q12, Q13, and Q14; and one half-bridge arm composed of Q15, Q16, Q17, and Q18), with each half-bridge arm including the midpoints of two high-frequency arms. At this time, the resonant converter module is a three-phase LLC network, including three transformers. The secondary windings of the three transformers are connected in a star configuration, and the secondary windings of the three transformers are connected to a three-phase diode bridge (D31, D32, D33, D34, D35, and D36), which rectifies to obtain a DC voltage.
[0035] This application also provides a circuit control method for controlling the isolated power conversion circuit described above. The method includes: during the operation of the power conversion circuit, driving a set of low-frequency bidirectional switches to conduct at a low frequency, connecting one phase input terminal to the DC midpoint of the high-frequency bridge arm modulation module in the isolated power conversion circuit; that is, connecting the input terminal with the highest voltage value among the three phase input terminals to the DC positive terminal of the high-frequency bridge arm modulation module, and connecting the input terminal with the lowest voltage value to the DC negative terminal of the high-frequency bridge arm modulation module; driving the low-frequency bidirectional switch corresponding to the input terminal with the intermediate voltage value to conduct at a low frequency, connecting the input terminal with the DC midpoint of the high-frequency bridge arm modulation module. Then, driving the high-frequency bridge arm modulation module to perform high-frequency modulation on the phase currents of the DC positive terminal, the DC midpoint, and the DC negative terminal of the high-frequency bridge arm modulation module to perform power factor correction.
[0036] It is understood that the single-stage high-frequency modulation isolated power conversion circuit provided in this application embodiment can be integrated into an electronic device or installed on different electronic devices, and the specific implementation is not limited here. In the several embodiments provided in this application, it should be understood that the disclosed circuits and methods can be implemented in other ways. For example, the circuit embodiments described above are merely illustrative. For example, the division of units is merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another circuit, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate; components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of this embodiment.
[0037] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.
[0038] The above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of the embodiments of this application.
Claims
1. A single-stage high-frequency modulation isolated power conversion circuit, characterized in that, include: Three-phase AC voltage source, rectifier module, three sets of low-frequency bidirectional switches, and high-frequency bridge arm modulation module; The ports of the high-frequency bridge arm modulation module include: a DC positive terminal, a DC level midpoint, a DC negative terminal, and the midpoints of the two high-frequency bridge arms; The rectifier module is used to rectify the three-phase AC current input from the three-phase AC voltage source; the first terminal of the rectifier module is connected to the DC negative terminal of the high-frequency bridge arm modulation module, and the second terminal of the rectifier module is connected to the DC positive terminal of the high-frequency bridge arm modulation module. The three-phase AC voltage source includes three-phase input terminals. The first terminals of the three sets of low-frequency bidirectional switches are respectively connected to the input terminals of different phases, and the second terminals of the three sets of low-frequency bidirectional switches are connected to the DC level midpoint of the high-frequency bridge arm modulation module. The midpoints of the two high-frequency bridge arms of the high-frequency bridge arm modulation module serve as circuit output ports. The high-frequency bridge arm modulation module is used to perform high-frequency modulation on the phase current of the DC positive terminal, the DC level midpoint, and the DC negative terminal of the high-frequency bridge arm modulation module, and output the high-frequency modulated current through the two midpoints of the high-frequency bridge arms.
2. The isolated power conversion circuit according to claim 1, characterized in that, The low-frequency bidirectional switch includes: a first low-frequency switching transistor and a second low-frequency switching transistor; The input terminal of the first low-frequency switch is connected to a phase input terminal, and the input terminal of the second low-frequency switch is connected to the midpoint of the DC level of the high-frequency bridge arm modulation module. The output terminal of the first low-frequency switch is connected to the output terminal of the second low-frequency switch.
3. The isolated power conversion circuit according to claim 1, characterized in that, The high-frequency bridge arm modulation module includes a half-bridge arm, which includes a first switch, a second switch, a third switch, and a fourth switch. The first switch, the second switch, the third switch, and the fourth switch are connected in series; The input terminal of the first switch is the positive DC terminal of the half-bridge arm, and the output terminal of the fourth switch is the negative DC terminal of the half-bridge arm. The series connection between the second switch and the third switch is the midpoint of the DC level of the half-bridge arm; The series connection between the first and second switching transistors is the midpoint of the first high-frequency bridge arm of the half-bridge arm, and the series connection between the third and fourth switching transistors is the midpoint of the second high-frequency bridge arm of the half-bridge arm.
4. The isolated power conversion circuit according to claim 3, characterized in that, The resonant conversion module includes a resonant unit, a transformer, and a rectifier unit; The midpoint of the first high-frequency bridge arm of the half-bridge arm is connected to the midpoint of the second high-frequency bridge arm of the half-bridge arm via the resonant unit and the primary winding of the transformer. The secondary winding of the transformer is connected to the rectifier unit.
5. The isolated power conversion circuit according to claim 1, characterized in that, The high-frequency bridge arm modulation module includes one or more half-bridge arms.
6. The isolated power conversion circuit according to claim 1, characterized in that, The resonant conversion module includes a transformer; The transformer can be connected in series, in parallel, in a star or delta configuration.
7. The isolated power conversion circuit according to claim 1, characterized in that, When the phase line voltage of the target phase input terminal among the three-phase input terminals is at the intermediate voltage value, the low-frequency bidirectional switch of the target phase input terminal is turned on.
8. A circuit control method, characterized in that, The circuit control method is used to control the isolated power conversion circuit as described in any one of claims 1 to 7, including: During the operation of the isolated power conversion circuit, a set of low-frequency bidirectional switches is turned on by low-frequency drive, so that one phase input terminal is connected to the DC level midpoint of the high-frequency bridge arm modulation module in the isolated power conversion circuit. The high-frequency bridge arm modulation module is driven to perform high-frequency modulation on the phase current of the DC positive terminal, the DC level midpoint, and the DC negative terminal of the high-frequency bridge arm modulation module.