Satellite power supply fault-isolated multi-modal resonant dc-dc converter and modulation method

Abstract

The application discloses a satellite power supply fault isolation type multi-mode resonant DC converter and a modulation method, belongs to the technical field of DC-DC conversion, and comprises a primary switching unit, a flying capacitor unit, a double-resonance unit and a secondary switching unit. The primary switching unit is composed of upper and lower bridge arm branches, and the flying capacitor unit is connected in a Dickson ladder mode. The secondary switching unit comprises a first rectifier switch tube, a bridge switch tube and a second rectifier switch tube connected in series. The double-resonance unit comprises a first resonance unit and a second resonance unit without magnetic coupling. The internal DC blocking resonance capacitor is equivalent to an open circuit in a DC steady state, and can block the continuous application of high voltage of an input bus to an output end through a power transmission path when a drain-source breakdown short circuit fault occurs in a primary side power switch tube. The application can realize zero-current soft switching within a designed load range, and realize stable multi-mode step-down conversion under a wide input range without increasing the number of main power devices and changing the physical connection.

Description

Technical Field

[0001] This invention relates to the field of DC-DC conversion technology, and in particular to a fault-isolated multimode resonant DC-DC converter and modulation method for satellite power supplies. Background Technology

[0002] As aerospace satellite platforms develop towards higher power and longer lifespan, their primary power buses are powered by a combination of solar cell arrays and battery banks. The bus voltage fluctuates over a wide range, placing stringent requirements on the power density, reliability, and single-point fault isolation capabilities of the power conversion devices. Switched-capacitor DC-DC converters have attracted widespread attention in high-power-density DC power supply scenarios such as aerospace satellite power supplies due to their absence of magnetic components, ease of integration, and high power density.

[0003] To alleviate the "capacitive hard charging" problem in traditional switched-capacitor topologies (i.e., during switching mode switching, capacitors with potential mismatch are directly connected through the switching transistor, triggering transient inrush current pulses; this charge redistribution loss is independent of the circuit parasitic resistance and cannot be suppressed by reducing the circuit resistance), existing technologies have proposed resonant switched-capacitor schemes, introducing inductors into the charging and discharging circuit to achieve soft charging. Among these, the Dickson-type flying capacitor cascade topology is widely used in high-power-density DC-DC conversion due to its low voltage stress on the switching devices and ease of extension to higher orders; however, its fixed step-down ratio makes it difficult to adapt to a wide input range, and a DC conduction path always exists between its primary and secondary sides, lacking DC blocking capability for single-point faults. Simultaneously, to block the DC propagation path of single-point faults (in traditional switched-capacitor topologies, the primary input and secondary output are only connected by semiconductor switches and capacitors; a permanent short circuit, such as drain-source breakdown of a single transistor, can directly transmit high voltage from the input bus to the output), existing technologies often employ magnetic isolation topologies based on high-frequency transformers.

[0004] However, the above solutions still have limitations under the dual constraints of wide input voltage range and high power density: on the one hand, the magnetic core volume of the magnetic isolation solution is relatively large, which limits the further improvement of power density. Moreover, when faced with wide-range input voltage disturbances, the switching frequency of the resonant converter needs to be offset significantly, and the semiconductor devices are prone to losing soft-switching conditions, making it difficult to maintain high efficiency across the entire input range. On the other hand, traditional fixed-ratio DC converters are difficult to adapt to wide-range fluctuations in the input bus voltage, and the output voltage cannot be stabilized in the target range. Furthermore, existing resonant soft-charging solutions and fault isolation methods are usually independent of each other and difficult to address simultaneously within the same topology.

[0005] Therefore, there is an urgent need for a DC-DC converter topology that combines soft-switching capability, single-point fault isolation capability, and wide input range adaptability to meet the application requirements of aerospace satellite power supplies for high power density, high reliability, and wide bus voltage adaptability. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a fault-isolated multimode resonant DC-DC converter and modulation method for satellite power supply, which achieves zero-current soft switching within the design load range, blocks the continuous application of high voltage from the input bus to the output terminal through the power transmission path when a drain-source short-circuit fault occurs in the primary-side power switch, and achieves stable multimode buck conversion over a wide input range without increasing the number of main power devices or changing the physical connections.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A fault-isolated multimode resonant DC-DC converter for satellite power supply.

[0009] It includes a primary switching unit, a flying capacitor unit, a dual resonant unit, and a secondary switching unit;

[0010] The primary switching unit includes an upper bridge arm branch and a lower bridge arm branch, each consisting of N / 2 main switching transistors connected in series, where N is an even number not less than 6; the ends of the upper bridge arm branch and the lower bridge arm branch are connected to each other, and their beginning ends form a positive input terminal and a negative input terminal, respectively.

[0011] The flying capacitor unit includes N / 2-1 flying capacitors, and each flying capacitor is connected between the corresponding intermediate nodes of the upper and lower bridge arm branches in a Dickson ladder manner.

[0012] The secondary switching unit includes a first rectifier switch, a bridge switch, and a second rectifier switch connected in series. The first end of the bridge switch is connected to the first rectifier switch, and the second end is connected to the second rectifier switch. The end of the first rectifier switch away from the bridge switch and the end of the second rectifier switch away from the bridge switch respectively constitute the positive output terminal and the negative output terminal.

[0013] The dual resonant unit includes a first resonant unit and a second resonant unit, both composed of a resonant inductor and a DC blocking resonant capacitor connected in series. The first resonant unit is connected between the end of the upper bridge arm branch and the connection node of the bridging switch and the second rectifier switch. The second resonant unit is connected between the negative input terminal and the connection node of the first rectifier switch and the bridging switch. The two DC blocking resonant capacitors are used to block the continuous application of high voltage from the input bus to the output terminal when a drain-source breakdown short-circuit fault occurs in the primary-side power switch.

[0014] The converter is configured to switch between at least two discrete buck ratios by changing the turn-on timing of each main switch, bridge switch, first rectifier switch and second rectifier switch, so that each flying capacitor presents different series and parallel connection relationships.

[0015] A further improvement of the technical solution of the present invention is that: N is 8; the upper bridge arm branch includes a first switch S1 to a fourth switch S4, the lower bridge arm branch includes a fifth switch S5 to an eighth switch S8, and the bridging switch, the first rectifier switch, and the second rectifier switch are S9, S1, S2, S3, S4, S5, S6, S7, S8, S9, S8 ... 10 and S 11 The three flying capacitors are the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3.

[0016] A further improvement of the technical solution of the present invention is that: the four main switching transistors of the upper bridge arm branch are, in order, the first to the fourth switching transistors from the positive input terminal to the connection terminal of the upper bridge arm branch and the lower bridge arm branch; the four main switching transistors of the lower bridge arm branch are, in order, the fifth to the eighth switching transistors from the negative input terminal to the connection terminal; and the three flying capacitors are, in order, the first flying capacitor, the second flying capacitor, and the third flying capacitor along the upper bridge arm branch from the positive input terminal to the connection terminal.

[0017] The converter includes three discrete buck modes:

[0018] In the first discrete buck mode, the converter operates at a buck ratio of 4:1;

[0019] In the second discrete buck mode, the converter operates at a buck ratio of 4:2;

[0020] In the third discrete buck mode, the converter operates at a buck ratio of 4:3.

[0021] A further improvement of the technical solution of this invention lies in that: in the first discrete buck mode, one switching cycle consists of eight sequentially occurring operating modes, denoted as mode 1a to mode 1h, specifically:

[0022] Mode 1a: The first switch S1, the sixth switch S6, the seventh switch S7, the eighth switch S8 and the bridge switch S9 are turned on. The positive input terminal injects energy into the first flying capacitor C1 through the first switch S1, and forms a series resonant circuit with the dual resonant unit.

[0023] Mode 1b: The discharge mode of mode 1a; fifth switch S5, sixth switch S6, seventh switch S7, eighth switch S8, first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0024] Mode 1c: The second switch S2, the fifth switch S5, the seventh switch S7, the eighth switch S8 and the bridge switch S9 are turned on, and energy is transferred from the first flying capacitor C1 to the second flying capacitor C2, forming a series resonant circuit with the dual resonant unit.

[0025] Mode 1d: The discharge mode of mode 1c; its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0026] Mode 1e: The third switch S3, the fifth switch S5, the sixth switch S6, the eighth switch S8 and the bridge switch S9 are turned on, and energy is transferred from the second flying capacitor C2 to the third flying capacitor C3, forming a series resonant circuit with the dual resonant unit.

[0027] Mode 1f: The discharge mode of mode 1e; its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0028] Mode 1g: The fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7 and the bridge switch S9 are turned on, and the third flying capacitor C3 acts as an energy source to release energy to the resonant circuit and forms a series resonant circuit with the dual resonant unit.

[0029] Mode 1h: This is the discharge mode of mode 1g; its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit.

[0030] A further improvement of the technical solution of this invention lies in the following: In the second discrete buck mode, one switching cycle consists of four sequentially occurring operating modes, denoted as modes 2a to 2d, wherein modes 2a and 2c are two charging modes using complementary primary switch combinations, and modes 2b and 2d are the subsequent two discharging modes. The bridging switch S9 is turned on in the two charging modes; specifically:

[0031] Mode 2a: The first switch S1, the second switch S2, the seventh switch S7, the eighth switch S8 and the bridge switch S9 are turned on. The positive input terminal injects energy into the second flying capacitor C2 through the first switch S1 and the second switch S2 in series, and forms a series resonant circuit with the dual resonant unit.

[0032] Mode 2b: The discharge mode of mode 2a; fifth switch S5, sixth switch S6, seventh switch S7, eighth switch S8, first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0033] Mode 2c: The third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, and the bridging switch S9 are turned on. The second flying capacitor C2 participates in the resonant energy transfer again in a path symmetrical and complementary to that of Mode 2a, and forms a series resonant circuit with the dual resonant unit, so that its DC bias voltage is naturally maintained at V. in / 2, the current stress of each switch is evenly distributed;

[0034] Mode 2d: the discharge mode of mode 2c; fifth switch S5, sixth switch S6, seventh switch S7, eighth switch S8, first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit.

[0035] A further improvement of the technical solution of this invention lies in the following: In the third discrete buck mode, the timing structure of the third discrete buck mode is mirror-symmetrical to the timing structure of the first discrete buck mode, the energy transfer order is reversed compared to the first discrete buck mode, and one switching cycle consists of eight sequentially occurring working modes, denoted as modes 3a to 3h, where odd-numbered modes are charging modes and even-numbered modes are subsequent discharging modes, and the bridging switch S9 is turned on in each charging mode; specifically:

[0036] Mode 3a: The first switch S1, the second switch S2, the third switch S3, the eighth switch S8 and the bridge switch S9 are turned on. The input power supply connected between the positive input terminal and the negative input terminal and the third flying capacitor C3 are recombined to form an energy source, and form a series resonant circuit with the dual resonant unit.

[0037] Mode 3b: The discharge mode of mode 3a; fifth switch S5, sixth switch S6, seventh switch S7, eighth switch S8, first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0038] Mode 3c: The first switch S1, the second switch S2, the fourth switch S4, the seventh switch S7 and the bridge switch S9 are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the third flying capacitor C3 and the second flying capacitor C2, form an energy source, which in turn forms a series resonant circuit with the dual resonant unit.

[0039] Mode 3d: The discharge mode of mode 3c; its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0040] Mode 3e: The first switch S1, the third switch S3, the fourth switch S4, the sixth switch S6 and the bridge switch S9 are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the second flying capacitor C2 and the first flying capacitor C1, recombines to form an energy source, and forms a series resonant circuit with the dual resonant unit.

[0041] Mode 3f: The discharge mode of mode 3e; its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0042] Mode 3g: The second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5 and the bridging switch S9 are turned on, and the first flying capacitor C1 alone serves as the energy source to complete the energy transfer, and forms a series resonant circuit with the dual resonant unit.

[0043] Mode 3h: This is the discharge mode of mode 3g; its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit.

[0044] A further improvement of the technical solution of the present invention lies in that: the first resonant unit and the second resonant unit reconstruct the charging and discharging circuit into a second-order underdamped resonant circuit, and the conduction time of each operating mode matches the resonant half-cycle of the corresponding equivalent resonant circuit, so that all power switching transistors perform commutation when the resonant current naturally crosses zero, thereby achieving zero-current soft switching. A further improvement of the technical solution of the present invention lies in that: the first resonant inductor and the second resonant inductor are not magnetically coupled to each other.

[0045] A further improvement of the technical solution of the present invention is that it also includes an input filter unit connected in parallel between the positive input terminal and the negative input terminal, and an output filter unit connected in parallel between the positive output terminal and the negative output terminal.

[0046] A modulation method for a fault-isolated multimode resonant DC-DC converter for satellite power supply includes the following steps:

[0047] Step 1: Set the charging and discharging alternation timing: Within one switching cycle, make the converter alternate between charging mode and discharging mode, with each charging mode immediately followed by a discharging mode, and the conduction topology of each discharging mode is the same.

[0048] Step 2: Execute charging mode: Control the bridge switch S9 to turn on, connect the two resonant branches where the first resonant unit and the second resonant unit are located in series, and make the selected flying capacitor and the series resonant branch form a second-order underdamped resonant circuit, and the charging current is a sinusoidal half-wave.

[0049] Step 3: Execute discharge mode: Control the first rectifier switch S 10 With the second rectifier switch S 11 The circuit is turned on, and the first switch S1 to the fourth switch S4 in the upper arm branch is turned off, while the fifth switch S5 to the eighth switch S8 in the lower arm branch is turned on, so that the energy stored in the dual resonant unit is released to the load through the secondary switch unit.

[0050] Step 4: Switching the buck ratio: Switching between the three discrete buck modes by changing the values ​​of each main switch, bridge switch S9, and first rectifier switch S... 10 With the second rectifier switch S 11 The conduction timing is reconstructed to reconfigure the series-parallel connection relationship of the first flying capacitor C1 to the third flying capacitor C3, so that the converter operates at one of the following three buck ratios, where m is the sequence number of the discrete buck mode, taking values ​​of 1, 2, and 3:

[0051] When m=1, it corresponds to the 4:1 mode, V o =V in / 4;

[0052] When m=2, it corresponds to the 4:2 mode, V o =V in / 2;

[0053] When m=3, it corresponds to the 4:3 mode, V o =3V in / 4; Compare the input voltage with the preset mode switching threshold, and select the mode number m according to the comparison result so that the output voltage falls into the preset target range;

[0054] Step 5: Implement zero-current soft switching: Set the conduction time of each operating mode according to the natural zero-crossing time of the resonant current, and reserve a zero-current margin so that all eleven power switching transistors can perform commutation when the resonant current naturally crosses zero.

[0055] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0056] 1. This invention symmetrically embeds a dual resonant unit consisting of a resonant inductor and a DC blocking resonant capacitor in the energy interaction circuit between the front-end flying capacitor cascade structure and the back-end rectifier unit. This reconstructs the originally low-damping pure RC charging and discharging circuit into a second-order underdamped resonant circuit, so that the charging and discharging current is transformed from an exponentially decaying pulse into a sinusoidal half-wave, thereby achieving zero-current soft switching within the design load range and eliminating capacitive hard charging losses.

[0057] 2. The DC-blocking resonant capacitor in this invention transfers AC power between the primary and secondary sides through continuous alternating charging and discharging during high-frequency operation. Under DC steady-state conditions, it presents an equivalent open circuit, cutting off the DC path from the primary bus high voltage to the secondary low voltage side. This achieves functional isolation against drain-source short-circuit faults of the primary-side power switch without relying on a high-frequency transformer, preventing the continuous application of high voltage from the input bus to the output terminal via the power transmission path, and avoiding the volume and weight costs associated with magnetic isolation schemes. Unlike conventional resonant switched capacitor schemes where the resonant capacitor is only used for soft charging, the DC-blocking resonant capacitor of this invention is connected in series on the only power transmission path between the primary and secondary sides, serving as both a resonant element and a DC-blocking element. Therefore, when a fault such as drain-source short-circuit occurs on the high-voltage primary side, the DC-blocking resonant capacitor can withstand the DC fault voltage, causing the fault current propagating through the main power path to decay to zero after a transient state, thereby blocking the propagation of steady-state DC faults and providing time margin for system-level fault detection and clearing, reducing the risk of damage to sensitive loads on the secondary low voltage side and cascading failures.

[0058] 3. This invention employs a Dixon structure with cascaded multi-stage flying capacitors. Topologically, this structure can be extended to higher orders by adding pairs of main switches and corresponding flying capacitors. In the fourth-order embodiment with N=8, without increasing the number of main power semiconductor devices or changing the physical hardware connections, the series-parallel relationship of each flying capacitor can be reconstructed simply by changing the switching timing. This allows the converter to operate in three discrete buck modes (4:1, 4:2, and 4:3) (i.e., output voltage V...). o =(m / 4)·V in Switching between m∈{1,2,3}, thereby stabilizing the output voltage within the target range over a wide input voltage fluctuation range, and realizing multi-mode fault isolation buck conversion.

[0059] 4. This invention combines soft-switching capability, single-point fault blocking capability, and wide input range adaptability with a single topology. In all three buck modes, all eleven power switches achieve zero-current soft switching within the design load range. The switching sequence frequency of each mode is mainly set based on the passive resonance parameters and combined with the reserved zero current margin to achieve stable commutation, enabling the converter to operate stably as an open-loop DC transformer under a wide input range. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a schematic diagram of the structure of a fault-isolated multimode resonant DC-DC converter for satellite power supply provided by the present invention;

[0062] Figure 2 This is a schematic diagram of the structure of a fault-isolated multimode resonant DC-DC converter for satellite power supply (using a fourth-order Dickson structure as an example) provided in an embodiment of the present invention;

[0063] Figure 3a This is a schematic diagram of the conduction state of the 1a charging mode that occurs sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0064] Figure 3b This is a schematic diagram of the conduction state of the 1b discharge mode that occurs sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0065] Figure 3c This is a schematic diagram of the conduction state of the 1c charging mode that occurs sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0066] Figure 3d This is a schematic diagram of the conduction state of the 1d discharge mode that appears sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0067] Figure 3e This is a schematic diagram of the conduction state of the 1e charging mode that appears sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0068] Figure 3f This is a schematic diagram of the conduction state of the 1f discharge mode that occurs sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0069] Figure 3g This is a schematic diagram of the conduction state of the 1g charging mode that appears sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0070] Figure 3h This is a schematic diagram of the conduction state of the 1-hour discharge mode that occurs sequentially within one switching cycle in the 4:1 buck mode in an embodiment of the present invention.

[0071] Figure 4a This is a schematic diagram of the conduction state of the 2a charging mode that occurs sequentially within one switching cycle in the 4:2 buck mode in an embodiment of the present invention.

[0072] Figure 4b This is a schematic diagram of the conduction state of the 2b discharge mode that occurs sequentially within one switching cycle in the 4:2 buck mode in an embodiment of the present invention.

[0073] Figure 4c This is a schematic diagram of the conduction state of the 2c charging mode that occurs sequentially within one switching cycle in the 4:2 buck mode in an embodiment of the present invention.

[0074] Figure 4d This is a schematic diagram of the conduction state of the 2d discharge mode that appears sequentially within one switching cycle in the 4:2 buck mode in an embodiment of the present invention.

[0075] Figure 5a This is a schematic diagram of the conduction state of the 3a charging mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0076] Figure 5b This is a schematic diagram of the conduction state of the 3b discharge mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0077] Figure 5c This is a schematic diagram of the conduction state of the 3C charging mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0078] Figure 5d This is a schematic diagram of the conduction state of the 3d discharge mode that appears sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0079] Figure 5e This is a schematic diagram of the conduction state of the 3e charging mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0080] Figure 5f This is a schematic diagram of the conduction state of the 3f discharge mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0081] Figure 5g This is a schematic diagram of the conduction state of the 3G charging mode that appears sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0082] Figure 5h This is a schematic diagram of the conduction state of the 3h discharge mode that occurs sequentially within one switching cycle in the 4:3 buck mode in an embodiment of the present invention.

[0083] Figure 6 This is a multi-mode switching dynamic response waveform in an embodiment of the present invention, showing the waveform of the converter switching between three discrete buck ratios by changing the switching timing during the step change of the input voltage over a wide range, maintaining the output voltage in the target range, and the waveform of the controlled step change of the output voltage at the boundary of each mode switching.

[0084] The components are as follows: 1. Positive input terminal; 2. Negative input terminal; 3. Positive output terminal; 4. Negative output terminal; 5. Input filtering unit; 6. Output filtering unit; 7. First upper bridge arm switch unit; 8. Second upper bridge arm switch unit; 9. Third upper bridge arm switch unit; 10. Fourth upper bridge arm switch unit; 11. First lower bridge arm switch unit; 12. Second lower bridge arm switch unit; 13. Third lower bridge arm switch unit; 14. Fourth lower bridge arm switch unit; 15. First energy storage unit; 16. Second energy storage unit; 17. Third energy storage unit; 18. First resonant unit; 19. Second resonant unit; 20. Bridging switch unit; 21. First rectifier switch unit; 22. Second rectifier switch unit. Detailed Implementation

[0085] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or device.

[0086] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0087] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0088] like Figure 1 As shown, a fault-isolated multimode resonant DC-DC converter for satellite power supply includes: a positive input terminal, a negative input terminal, a positive output terminal, a negative output terminal, an input filter unit, an output filter unit, a primary switching unit, a flying capacitor unit, a dual resonant unit, and a secondary switching unit.

[0089] The primary switching unit includes an upper bridge arm branch consisting of N / 2 main switching transistors connected in series and a lower bridge arm branch consisting of N / 2 main switching transistors connected in series, where N is an even number not less than 6; the ends of the upper and lower bridge arm branches are electrically connected; the beginning of the upper bridge arm branch is connected to the positive input terminal, and the beginning of the lower bridge arm branch is connected to the negative input terminal; the input filtering unit is connected in parallel between the positive and negative input terminals, and the output filtering unit is connected in parallel between the positive and negative output terminals;

[0090] The flying capacitor unit includes N / 2-1 flying capacitors. Each flying capacitor is connected between the corresponding intermediate nodes of the upper and lower bridge arm branches in a Dickson ladder manner, forming an N / 2-stage voltage divider structure.

[0091] The secondary switching unit includes a first rectifier switch, a bridge switch, and a second rectifier switch connected in series. The first terminal of the bridge switch is connected to the first rectifier switch, and the second terminal is connected to the second rectifier switch. The other terminal of the first rectifier switch is electrically connected to the positive output terminal, and the other terminal of the second rectifier switch is electrically connected to the negative output terminal. Let n = N / 2, and the main switches of the upper bridge arm are numbered S1 to S2 sequentially. n The main switch tubes of the lower bridge arm are numbered S sequentially. n+1 ~S 2n The bridging switch, the first rectifier switch, and the second rectifier switch are respectively numbered S. 2n+1 S 2n+2 and S 2n+3 The flying capacitors are numbered C1 to C1 in sequence. n-1 .

[0092] The dual resonant unit includes a first resonant unit and a second resonant unit that are not magnetically coupled. The first resonant unit is connected between the end of the upper bridge arm branch and the second terminal of the bridge switch. The second resonant unit is connected between the negative input terminal and the first terminal of the bridge switch. The first resonant unit includes a first resonant inductor and a first DC blocking resonant capacitor connected in series. The second resonant unit includes a second resonant inductor and a second DC blocking resonant capacitor connected in series. The first resonant inductor and the second resonant inductor are independent of each other and are not magnetically coupled. The first DC blocking resonant capacitor and the second DC blocking resonant capacitor are both equivalent to open circuits under DC steady state. They are used to block the continuous application of high voltage from the input bus to the output terminal through the power transmission path when a drain-source breakdown short circuit fault occurs in the primary-side power switch.

[0093] In charging mode, the bridging switch connects the two resonant branches containing the first and second resonant units in series; in discharging mode, the two rectifier switches are turned on, sending energy to the load between the positive and negative output terminals.

[0094] The converter is configured to switch between multiple discrete buck modes by changing the conduction timing of each main switch, bridge switch, and rectifier switch, without increasing the number of main power devices or changing the physical connections. This allows the flying capacitors in the flying capacitor unit to have different series-parallel connection relationships. For the fourth-order embodiment with N=8 described below, the ideal voltage gain for the three buck modes is V. o =(m / 4)·V in , where m∈{1,2,3}; the two DC blocking resonant capacitors present an equivalent open circuit under DC steady state, which is used to block the high voltage of the input bus from being continuously applied to the output terminal through the power transmission path when the drain-source breakdown short circuit fault occurs in the primary side power switch. The resonant inductor and the DC blocking resonant capacitor reconstruct the charging and discharging circuit into a second-order underdamped resonant circuit, so that all power switches can achieve zero-current soft switching within the design load range.

[0095] Example

[0096] like Figure 2 As shown, taking a fourth-order Dickson structure as an example, a fault-isolated multimode resonant DC-DC converter for satellite power supplies is presented. This converter includes a primary switching unit consisting of eight main switches and three flying capacitors cascaded in a Dickson ladder configuration; a secondary switching unit consisting of one bridging switch and two rectifier switches; and dual resonant units symmetrically embedded in the primary and secondary energy interaction loops. Each resonant unit consists of a resonant inductor and a DC-blocking resonant capacitor connected in series. The resonant inductor reconstructs the charging and discharging loop into a second-order underdamped resonant loop, enabling the converter to achieve zero-current soft switching within the designed load range. The DC-blocking resonant capacitor presents an equivalent open circuit under DC steady-state conditions. When a drain-source short-circuit fault occurs in the primary-side power switch, it blocks the high voltage from the input bus from being continuously applied to the output through the main power path, and causes the fault current to decay to zero after a transient state, providing a time margin for system-level fault detection and clearing, and reducing the risk of damage to the secondary low-voltage chip load. Switching between three discrete buck ratios can be achieved simply by changing the switching timing, realizing stable multimode buck conversion over a wide input voltage range.

[0097] Specifically, it includes: positive input terminal 1, negative input terminal 2, positive output terminal 3, negative output terminal 4, and input filter unit 5 (input filter capacitor C). in ), Output filter unit 6 (output filter capacitor C) o It consists of a primary switching unit, a flying capacitor unit, a dual resonant unit, and a secondary switching unit.

[0098] The primary switching unit includes: a first upper bridge arm switching unit 7, a second upper bridge arm switching unit 8, a third upper bridge arm switching unit 9, a fourth upper bridge arm switching unit 10, a first lower bridge arm switching unit 11, a second lower bridge arm switching unit 12, a third lower bridge arm switching unit 13, and a fourth lower bridge arm switching unit 14. The first upper bridge arm switching unit 7, the second upper bridge arm switching unit 8, the third upper bridge arm switching unit 9, the fourth upper bridge arm switching unit 10, the first lower bridge arm switching unit 11, the second lower bridge arm switching unit 12, the third lower bridge arm switching unit 13, and the fourth lower bridge arm switching unit 14 are respectively: a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, and an eighth switch S8. Among them, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are the main charging tubes of the upper bridge arm, forming the upper bridge arm branch. The fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 are the return current tubes of the lower bridge arm, forming the lower bridge arm branch. The upper bridge arm branch and the lower bridge arm branch work together to charge the input terminal V. in Energy is injected into the flying capacitor unit.

[0099] The flying capacitor unit includes: a first energy storage unit 15, a second energy storage unit 16, and a third energy storage unit 17. The first energy storage unit 15, the second energy storage unit 16, and the third energy storage unit 17 are respectively: a first flying capacitor C1, a second flying capacitor C2, and a third flying capacitor C3. The flying capacitor unit is composed of the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3 cascaded in a Dickson ladder configuration to achieve a four-stage voltage divider. In the steady state of the 4:1 buck mode, the voltages of the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3 are all 3V. in / 4、V in / 2、V in / 4.

[0100] The dual resonant unit includes: a first resonant unit 18 and a second resonant unit 19 symmetrically arranged vertically. The first resonant unit 18 includes a first resonant inductor L connected in series with each other. r1 and the first DC blocking resonant capacitor C r1 The second resonant unit 19 includes a second resonant inductor L connected in series with each other. r2 Second DC blocking resonant capacitor C r2 The dual resonant unit and the selected flying capacitor form an LC oscillation circuit to realize a sinusoidal half-wave current; the DC blocking resonant capacitor blocks the DC path to ensure charge conservation under periodic steady state.

[0101] The secondary switching unit includes: a bridging switch unit 20, a first rectifier switch unit 21, and a second rectifier switch unit 22. The bridging switch unit 20, the first rectifier switch unit 21, and the second rectifier switch unit 22 are respectively: a bridging switch S9, a first rectifier switch S1, and a second rectifier switch S2. 10 Second rectifier switch S 11 In the charging mode, the bridging switch S9 connects the two resonant branches in series, and the first rectifier switch S... 10 With the second rectifier switch S 11 It conducts in the discharge mode and delivers energy to the load.

[0102] The connection relationships of the components are as follows:

[0103] Output filter unit 6 (output filter capacitor C) o ) connected in parallel between positive output terminal 3 and negative output terminal 4; input filter unit 5 (input filter capacitor C) in It is connected in parallel between positive input terminal 1 and negative input terminal 2;

[0104] Positive input terminal 1 and input filter unit 5 (input filter capacitor C) in The first terminal of the input filter unit 5 is connected to the drain of the first switching transistor S1; the negative input terminal 2, the second terminal of the input filter unit 5, and the drain of the fifth switching transistor S5 share a common terminal; the output filter unit 6 (output filter capacitor C) o The second end of the terminal is connected to the negative output terminal 4.

[0105] The source of the first switch S1 is connected to the drain of the second switch S2 and the first terminal of the first flying capacitor C1; the source of the second switch S2 is connected to the drain of the third switch S3 and the first terminal of the second flying capacitor C2; the source of the third switch S3 is connected to the drain of the fourth switch S4 and the first terminal of the third flying capacitor C3; the source of the fourth switch S4 is connected to the source of the eighth switch S8 and the first resonant inductor L. r1 The first end is connected.

[0106] The source of the fifth switch S5 is connected to the drain of the sixth switch S6 and the second terminal of the first flying capacitor C1; the source of the sixth switch S6 is connected to the drain of the seventh switch S7 and the second terminal of the second flying capacitor C2; the source of the seventh switch S7 is connected to the drain of the eighth switch S8 and the second terminal of the third flying capacitor C3; the second resonant inductor L... r2 The first terminal is connected to the negative input terminal 2.

[0107] First resonant inductor L r1 The second end is connected to the first DC blocking resonant capacitor C r1 The first terminal is connected to the first DC blocking resonant capacitor C. r1The second terminal is connected to the second terminal of the bridging switch S9 and the second rectifier switch S. 11 The second end is connected; the second resonant inductor L r2 The second terminal is connected to the second DC blocking resonant capacitor C. r2 The first end is connected to the second DC blocking resonant capacitor C. r2 The second terminal is connected to the first terminal of the bridging switch S9 and the first rectifier switch S 10 The second end is connected.

[0108] First rectifier switch S 10 The first terminal is connected to the output filter capacitor C o The first terminal is connected to the positive output terminal 3; the second rectifier switch S 11 The first terminal is connected to the negative output terminal 4; the output filter capacitor C o Connected in parallel between positive output terminal 3 and negative output terminal 4. First resonant inductor L r1 With the second resonant inductor L r2 These are two independent, non-magnetically coupled resonant inductors, symmetrically positioned relative to the bridge switch S9.

[0109] The embedding mechanism of the dual resonant unit in this invention is explained as follows:

[0110] Resonant inductor (first resonant inductor L) r1 With the second resonant inductor L r2 The embedding of the flying capacitor alters the impedance characteristics of the original topology. Before embedding, the charging and discharging circuit of the flying capacitor is a pure RC network, with the charging and discharging current exhibiting exponentially decaying pulse characteristics, and charge redistribution losses cannot be eliminated. After embedding, the circuit is reconstructed into a second-order underdamped resonant circuit, and the current waveform is transformed into a sinusoidal half-wave. The latter's losses are determined only by the circuit's parasitic resistance, which can be suppressed by reducing the device's circuit resistance, thereby achieving zero-current soft switching within the designed load range.

[0111] DC blocking resonant capacitor (first DC blocking resonant capacitor C) r1 With the second DC blocking resonant capacitor C r2 It serves a dual purpose in the main power circuit:

[0112] The resonant capacitance and resonant inductance together determine the resonant frequency and characteristic impedance of the converter. Specifically, the resonant angular frequency of the equivalent circuit formed by the series connection of the first and second resonant branches is approximately ω. r =(L r ·C eq ) -1 / 2 The corresponding resonant half-cycle is approximately T. r =π·(L r ·C eq ) 1 / 2 L rLet L be the equivalent resonant inductance of the series circuit, and L r =L r1 +L r2 C eq This is the series equivalent capacitance of the capacitors participating in resonance in the corresponding sub-mode; in the charging sub-mode, it includes the first DC blocking resonant capacitor, the second DC blocking resonant capacitor, and the selected flying capacitor; in the discharging mode, it is the series equivalent capacitance of the first DC blocking resonant capacitor and the second DC blocking resonant capacitor; since L r With C eq Primarily determined by passive components, for a given sub-mode, within the design load range, changes in input voltage and load current mainly affect the amplitude of the resonant current. The change in the resonant current at its natural zero-crossing time remains within the preset zero current margin. The switching sequence frequency of each operating mode is set according to the resonant half-cycle of the corresponding sub-mode. During steady-state operation, it also provides fault isolation to block DC faults. During normal operation of the high-frequency switch, the DC-blocking resonant capacitor transfers AC power between the primary and secondary sides through a continuous alternating charging and discharging process. When the system is under steady-state DC conditions, the DC-blocking resonant capacitor exhibits equivalent open-circuit characteristics, cutting off the DC charge coupling path between the primary and secondary sides. Therefore, even if a short-circuit fault occurs in the primary-side switch, the high voltage of the primary bus cannot be directly connected to the low-voltage secondary side through the main isolation circuit, thus achieving equivalent single-point fault blocking capability without relying on a high-frequency transformer. For satellite power applications, the aforementioned steady-state DC fault blocking effect provides time margin for fault detection and protection clearance, thereby reducing the risk of damage to the secondary low-voltage side processor chip, sensitive electronic loads, etc., and the risk of fault cascading and propagating throughout the entire system.

[0113] The following is a concluding statement regarding the ideal voltage gain of this invention:

[0114] The converter consists of several charging modes and several discharging modes with the same conduction topology, alternating in each switching cycle. The first DC blocking resonant capacitor C r1 The second DC blocking resonant capacitor C r2 Under periodic steady state, charge balance is satisfied, and the first resonant inductor L... r1 Second resonant inductor L r2 To maintain volt-second balance, each flying capacitor maintains charge conservation within a complete switching cycle. Based on these steady-state constraints, the flying capacitor unit is clamped into a voltage-second range within the Dickson ladder structure. in A series of equally spaced voltage steps, with a base of 4, mean that the steady-state voltages of the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3 successively approach 3V. in / 4、V in / 2、V in / 4. Changing the switching timing, i.e., changing the series-parallel combination of the selected flying capacitor relative to the resonant branch, is equivalent to selecting different voltage steps as the source of energy transfer to the load, thus obtaining three discrete ideal voltage gains; their unified expression is V o =(m / 4)·V in Where m∈{1,2,3}: when m=1, it corresponds to the 4:1 pattern, V o =V in / 4; When m=2, it corresponds to the 4:2 mode, V o =V in / 2; When m=3, it corresponds to the 4:3 mode, V o =3V in / 4. Since the above gain is entirely determined by the steady-state voltage step of the flying capacitor and the timing gating relationship, and is independent of the load current, and ideally independent of the value of the resonant element, the converter exhibits the characteristics of a fixed-ratio open-loop DC transformer in each mode.

[0115] A modulation method for a fault-isolated multimode resonant DC-DC converter for satellite power supply includes the following steps:

[0116] Step 1: Set the charging and discharging alternation timing: Within one switching cycle, make the converter alternate between charging mode and discharging mode, with each charging mode immediately followed by a discharging mode, and the conduction topology of each discharging mode is the same.

[0117] Step 2: Execute charging mode: Control the bridge switch S9 to turn on, connect the two resonant branches where the first resonant unit and the second resonant unit are located in series, and make the selected flying capacitor and the series resonant branch form a second-order underdamped resonant circuit, and the charging current is a sinusoidal half-wave.

[0118] Step 3: Execute discharge mode: Control the first rectifier switch S 10 With the second rectifier switch S 11 The circuit is turned on, and the first switch S1 to the fourth switch S4 in the upper arm branch is turned off, while the fifth switch S5 to the eighth switch S8 in the lower arm branch is turned on, so that the energy stored in the resonant unit is released to the load through the secondary switch unit.

[0119] Step 4: Switching the buck ratio: Switching between the three discrete buck modes by changing the main switches (first switch S1, second switch S2, third switch S3, fourth switch S4, fifth switch S5, sixth switch S6, seventh switch S7, and eighth switch S8), the bridge switch S9, and the first rectifier switch S8. 10 With the second rectifier switch S 11The conduction timing is reconstructed to reconfigure the series-parallel connection relationship of the first flying capacitor C1 to the third flying capacitor C3, so that the converter operates at one of the following three buck ratios, where m is the sequence number of the discrete buck mode, taking values ​​of 1, 2, and 3:

[0120] When m=1, it corresponds to the 4:1 mode, V o =V in / 4;

[0121] When m=2, it corresponds to the 4:2 mode, V o =V in / 2;

[0122] When m=3, it corresponds to the 4:3 mode, V o =3V in / 4; Compare the input voltage with a preset mode switching threshold with hysteresis, and select the mode number m according to the comparison result so that the output voltage falls into the preset target range; Latch the switching command when the input voltage exceeds the mode switching threshold, and perform mode switching when the resonant current approaches the natural zero crossing.

[0123] Step 5: Achieve zero-current soft switching: Ensure that the conduction time of each operating mode matches the resonant half-cycle of the corresponding equivalent resonant circuit. The equivalent resonant parameters include the series equivalent inductance of the first and second resonant inductors, and the equivalent capacitance formed by the DC blocking resonant capacitor and the flying capacitor participating in the resonance under the corresponding sub-mode. Within the design load range, the changes in input voltage and load current mainly affect the amplitude of the resonant current. The change in the resonant current at the moment of natural zero crossing remains within the preset zero current margin, so that all eleven power switching transistors operate in the zero-current soft-switching state.

[0124] Furthermore, the converter switches between three discrete buck ratios based on the range of the input voltage: determined by V o =(m / 4)·V in It is known that the smaller the buck mode number m, the lower the output voltage. Therefore, a smaller m is selected when the input voltage is high (e.g., 4:1 mode), and a larger m is selected when the input voltage is low (e.g., 4:3 mode) to keep the output voltage within the target range. Taking the nominal output of 12V and the input voltage of 16V to 60V in this embodiment as an example, 4:1, 4:2, and 4:3 cover the input voltage ranges of 32V to 60V, 20V to 32V, and 16V to 20V, respectively. The corresponding mode switching thresholds are 32V and 20V, and hysteresis can be set near the thresholds. The above switching is achieved only by changing the conduction timing of each switch, without increasing the number of devices or changing the physical connections.

[0125] The charging mode in step 2 and the discharging mode in step 3 above correspond to different sub-modes under the three voltage reduction ratios: the 4:1 mode corresponds to... Figures 3a to 3h4:2 mode corresponds Figures 4a to 4d 4:3 mode corresponds Figures 5a to 5h The operating modes in each mode are arranged alternately between charging and discharging modes, with each charging mode immediately followed by a discharging mode, and the conduction topology of each discharging mode is the same. The multi-mode switching dynamic response of the converter when the input voltage varies stepwise over a wide range is as follows: Figure 6 As shown.

[0126] Specifically, such as Figure 2 As shown, the proposed converter includes four upper bridge arm switches (first switch S1, second switch S2, third switch S3, and fourth switch S4), four lower bridge arm switches (fifth switch S5, sixth switch S6, seventh switch S7, and eighth switch S8), three flying capacitors (first flying capacitor C1, second flying capacitor C2, and third flying capacitor C3), and two DC blocking resonant capacitors (first DC blocking resonant capacitor C...). r1 The second DC blocking resonant capacitor C r2 Two resonant inductors (first resonant inductor L) r1 Second resonant inductor L r2 ) and three secondary switching transistors (bridge switch S9, first rectifier switch S1, and second rectifier switch S2). 10 With the second rectifier switch S 11 A fourth-order Dickson structure. When the input voltage V in When varying the voltage within the range of 16V to 60V, the first switching transistor S1 to the eighth switching transistor S8, as well as the bridging switching transistor S9 and the first rectifier switching transistor S... 10 Second rectifier switch S 11 By adjusting the conduction timing, the series and parallel connections of each flying capacitor can be reconstructed without increasing the number of main power devices or changing the physical connections. This allows the converter to be configured with three equivalent buck ratios, and the ideal gain relationship of the three modes can be uniformly expressed as: V o =(m / 4)·V in Where m∈{1,2,3}. Thus, the converter can adaptively adjust the discrete turns ratio over a wide input voltage fluctuation range to stabilize the output voltage within the target range. In each mode, the converter operates as an open-loop DC transformer, with each charging mode immediately followed by a discharging mode. The conduction topology of each discharging mode is the same, and charging and discharging alternate. In the discharging mode, all upper bridge arm switches are turned off, and the lower bridge arm switches (switches 5 through 8) and the secondary rectifier switches (switches 1 through 8) are switched off. 10 With the second rectifier switch S 11 When the circuit is turned on, the energy stored in the resonant unit is released to the load in a spatially symmetrical manner through the secondary switching unit.

[0127] The following describes the conduction configuration of the three discrete buck modes. In each mode, all switching transistors operate in a zero-current soft-switching state.

[0128] (1) The first discrete voltage reduction mode has a voltage reduction ratio of 4:1 (m=1, V o =V in / 4), such as Figures 3a to 3h As shown.

[0129] In this mode, a switching cycle consists of eight sequentially occurring operating modes, denoted as mode 1a to mode 1h. Odd-numbered modes are charging modes, and even-numbered modes are subsequent discharging (freewheeling) modes. Charging and discharging alternate. The bridging switch S9 is turned on in each charging mode to connect the upper and lower resonant branches in series. Specifically:

[0130] like Figure 3a As shown, in mode 1a: the first switch S1, the sixth switch S6, the seventh switch S7, the eighth switch S8 and the bridge switch S9 are turned on, and the positive input terminal injects energy into the first flying capacitor C1 through the first switch S1, and forms a series resonant circuit with the dual resonant unit.

[0131] like Figure 3b As shown, mode 1b is the discharge mode of mode 1a. The fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0132] like Figure 3c As shown, in mode 1c: the second switch S2, the fifth switch S5, the seventh switch S7, the eighth switch S8 and the bridging switch S9 are turned on, and energy is transferred from the first flying capacitor C1 to the second flying capacitor C2, forming a series resonant circuit with the dual resonant unit.

[0133] like Figure 3d As shown, mode 1d is the discharge mode of mode 1c. Its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0134] like Figure 3e As shown, in mode 1e: the third switch S3, the fifth switch S5, the sixth switch S6, the eighth switch S8 and the bridging switch S9 are turned on, and energy is transferred from the second flying capacitor C2 to the third flying capacitor C3, forming a series resonant circuit with the dual resonant unit.

[0135] like Figure 3f As shown, mode 1f is the discharge mode of mode 1e. Its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0136] like Figure 3g As shown, in mode 1g: the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7 and the bridging switch S9 are turned on, and the third flying capacitor C3 acts as an energy source to release energy to the resonant circuit and forms a series resonant circuit with the dual resonant unit.

[0137] like Figure 3h As shown, mode 1h is the discharge mode of mode 1g. Its conduction topology is the same as that of mode 1b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit.

[0138] In summary, within a complete switching cycle, energy is transferred sequentially through the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3. After the above four sets of charging-discharging modes alternately cycle, the output voltage stabilizes at 1 / 4 of the input voltage.

[0139] (2) The second discrete voltage reduction mode has a voltage reduction ratio of 4:2 (m=2, V o =V in / 2), such as Figures 4a to 4d As shown.

[0140] In this mode, one switching cycle consists of four sequentially occurring operating modes, denoted as modes 2a to 2d. Modes 2a and 2c are two charging modes using complementary primary switch combinations, and modes 2b and 2d are the subsequent two discharging modes. The bridging switch S9 is turned on in the two charging modes. Specifically:

[0141] like Figure 4a As shown, in mode 2a: the first switch S1, the second switch S2, the seventh switch S7, the eighth switch S8 and the bridge switch S9 are turned on. The positive input terminal injects energy into the second flying capacitor C2 through the first switch S1 and the second switch S2 in series, and forms a series resonant circuit with the dual resonant unit.

[0142] like Figure 4bAs shown, mode 2b is the discharge mode of mode 2a. The fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0143] like Figure 4c As shown, in mode 2c: the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, and the bridging switch S9 are turned on. The second flying capacitor C2 participates in the resonant energy transfer again in a path that is symmetrical and complementary to that of mode 2a, and forms a series resonant circuit with the dual resonant unit, so that its DC bias voltage is naturally maintained at V. in / 2, the current stress of each switch is evenly distributed;

[0144] like Figure 4d As shown, mode 2d is the discharge mode of mode 2c. The fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit.

[0145] In summary, within a complete switching cycle, through the alternating cycles of the two sets of charging-discharging modes, the output voltage stabilizes at 1 / 2 of the input voltage.

[0146] (3) The third discrete voltage reduction mode has a voltage reduction ratio of 4:3 (m=3, V o =3V in / 4), such as Figures 5a to 5h As shown.

[0147] The timing structure of the third discrete buck mode is mirror-symmetric to that of the first discrete buck mode. The energy transfer order is reversed compared to the first discrete buck mode. One switching cycle consists of eight sequentially occurring operating modes, denoted as modes 3a to 3h. Odd-numbered modes are charging modes, and even-numbered modes are the subsequent discharging modes. The bridging switch S9 is turned on in each charging mode. Specifically:

[0148] like Figure 5a As shown, in mode 3a: the first switch S1, the second switch S2, the third switch S3, the eighth switch S8 and the bridge switch S9 are turned on, and the input power supply connected between the positive input terminal and the negative input terminal and the third flying capacitor C3 are recombined to form an energy source, which forms a series resonant circuit with the dual resonant unit.

[0149] like Figure 5bAs shown, mode 3b is the discharge mode of mode 3a. The fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S... 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0150] like Figure 5c As shown, in mode 3c: the first switch S1, the second switch S2, the fourth switch S4, the seventh switch S7 and the bridge switch S9 are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the third flying capacitor C3 and the second flying capacitor C2, form an energy source, which in turn forms a series resonant circuit with the dual resonant unit.

[0151] like Figure 5d As shown, mode 3d is the discharge mode of mode 3c. Its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0152] like Figure 5e As shown, in mode 3e: the first switch S1, the third switch S3, the fourth switch S4, the sixth switch S6 and the bridge switch S9 are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the second flying capacitor C2 and the first flying capacitor C1, recombines to form an energy source, and forms a series resonant circuit with the dual resonant unit.

[0153] like Figure 5f As shown, mode 3f is the discharge mode of mode 3e. Its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1. 10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0154] like Figure 5g As shown, in mode 3g: the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5 and the bridging switch S9 are turned on, and the first flying capacitor C1 alone serves as the energy source to complete the energy transfer, and forms a series resonant circuit with the dual resonant unit.

[0155] like Figure 5h As shown, mode 3h is the discharge mode of mode 3g. Its conduction topology is the same as that of mode 3b, namely, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, and the first rectifier switch S1.10 and the second rectifier switch S 11 When the circuit is turned on, the resonant energy is released to the load through the secondary switching unit;

[0156] In summary, within a complete switching cycle, energy is transferred sequentially through the third flying capacitor C3, the second flying capacitor C2, and the first flying capacitor C1. After the above four sets of charging-discharging modes alternately cycle, the output voltage is stabilized at 3 / 4 of the input voltage.

[0157] The ideal gain V of the 4:3 buck mode is determined below by the self-consistency of charge conservation and voltage step. o =3V in / 4 is used for verification. As mentioned earlier, under the clamping effect of the Dickson ladder structure, the steady-state voltages of the first flying capacitor C1, the second flying capacitor C2, and the third flying capacitor C3 are 3V respectively. in / 4、V in / 2、V in / 4. In the four charging modes of the 4:3 mode, the selected flying capacitor and the input terminal are connected in different combinations to a resonant circuit formed by the upper and lower resonant branches connected in series through the bridge switch S9, so that the circuit presents the same voltage step to the secondary switching unit in each mode:

[0158] Charging Mode I: such as Figure 5a As shown, corresponding to mode 3a, the energy source is formed by the input power supply connected between the positive and negative input terminals and the third flying capacitor C3, with a step voltage of V. in -V C3 =V in -V in / 4=3V in / 4;

[0159] Charging Mode II: such as Figure 5c As shown, corresponding to mode 3c, the input power supply connected between the positive and negative input terminals is recombined with the second flying capacitor C2 and the third flying capacitor C3, and the step voltage is V. in -V C2 +V C3 =V in -V in / 2+V in / 4=3V in / 4;

[0160] Charging Mode III: such as Figure 5e As shown, corresponding to mode 3e, the input power supply connected between the positive and negative input terminals is recombined with the first flying capacitor C1 and the second flying capacitor C2, and the step voltage is V. in -V C1 +V C2 =V in-3V in / 4+V in / 2=3V in / 4;

[0161] Charging Mode IV: such as Figure 5g As shown, corresponding to mode 3g, the first flying capacitor C1 serves as the sole energy source, and the step voltage is V. C1 =3V in / 4.

[0162] The voltage step presented to the secondary side in all four charging modes is equal to 3V. in / 4, therefore the output voltage is stable at V o =3V in / 4, consistent with the ideal gain expression.

[0163] In terms of charge conservation, the four charging modes constitute a chain process of sequential mirror transfer along the flying capacitors: the third flying capacitor C3 is charged in charging mode I and discharged in charging mode II; the second flying capacitor C2 is charged in charging mode II and discharged in charging mode III; the first flying capacitor C1 is charged in charging mode III and discharged in charging mode IV. Since each mode shares the same resonant circuit and completes charge transfer within the same resonant half-cycle, the charge added to each flying capacitor in a complete switching cycle is equal to the charge released, resulting in a net charge of zero, satisfying the charge balance of the periodic steady state. Therefore, the 4:3 buck mode is self-consistent in terms of both voltage step and charge conservation, and the converter exhibits a fixed buck ratio of 4:3 (i.e., V0). o =3V in Open-loop DC transformer characteristics ( / 4).

[0164] Switching between the three discrete buck modes can be achieved simply by changing the turn-on sequence of each switch, without increasing the number of main power devices or changing the physical connections. In all three modes, all eleven power switches of the converter achieve zero-current soft switching within the design load range, so the converter can operate as an open-loop DC transformer with a wide input range.

[0165] To verify the above technical solution, a prototype with a nominal output of 12V / 10A (120W) was fabricated according to this embodiment. The first resonant inductor L... r1 With the second resonant inductor L r2 The inductance is approximately 150nH; the first flying capacitor C1, the second flying capacitor C2, the third flying capacitor C3, and the first DC blocking resonant capacitor C r1 With the second DC blocking resonant capacitor C r2 All use multiple capacitors connected in parallel, with a single-channel equivalent capacitance of approximately 2.2μF; the output filter capacitor C oEquivalent to approximately 100μF; the switching sequence frequency in 4:1 and 4:3 modes is approximately 78.6kHz, and in 4:2 mode it is approximately 152.69kHz. At input voltage V... in Under conditions varying from 16V to 60V, the converter switches between three buck modes by changing the switching timing, maintaining the output voltage within the design range of approximately 8V to 16V. Actual measurements show that the DC bias voltage of each flying capacitor stabilizes at approximately V in both 4:1 and 4:2 modes. in The charge conservation constraint of the flying capacitor unit was verified near the equidistant stepped area with a / 4 reference. The current waveforms of each switch were smooth sinusoidal half-waves and naturally returned to zero before the drive signal was turned off, achieving zero-current soft switching within the design load range of 0-120W. No obvious high-frequency parasitic ringing was observed at the commutation node. The control timing was set with a zero-current margin of approximately 50ns based on the calibrated resonant half-cycle to accommodate component parameter drift. The measured system efficiency of the 4:1 mode at approximately 70W operating point was approximately 96.85%, and the system efficiency at 120W full load operating point was approximately 96.5%. At 120W full load operating point, the system efficiencies of the 4:2 mode and 4:3 mode were approximately 96.3% and 95.8%, respectively. During the switching between the three modes, the output voltage changes stepwise with the input voltage according to the corresponding gain, and exhibits a controlled step change when crossing mode boundaries. After employing hysteresis loop judgment and zero-crossing synchronization, no cross-mode back-and-forth switching occurred, verifying its multi-mode buck capability over a wide input range. The dynamic response waveform for multi-mode switching is shown below. Figure 6 As shown.

[0166] When arranging circuits, it is also necessary to select devices and arrangement methods that meet the requirements of unidirectional current flow based on the operating characteristics of metal-oxide-semiconductor field-effect transistors or insulated-gate bipolar transistors.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has 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; and these 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 the present invention.

Claims

1. A fault-isolated multimode resonant DC-DC converter for satellite power supply, characterized in that, It includes a primary switching unit, a flying capacitor unit, a dual resonant unit, and a secondary switching unit; The primary switching unit includes an upper bridge arm branch and a lower bridge arm branch, each consisting of N / 2 main switching transistors connected in series, where N is an even number not less than 6; the ends of the upper bridge arm branch and the lower bridge arm branch are connected to each other, and their beginning ends form a positive input terminal and a negative input terminal, respectively. The flying capacitor unit includes N / 2-1 flying capacitors, and each flying capacitor is connected between the corresponding intermediate nodes of the upper and lower bridge arm branches in a Dickson ladder manner. The secondary switching unit includes a first rectifier switch, a bridge switch, and a second rectifier switch connected in series. The first end of the bridge switch is connected to the first rectifier switch, and the second end is connected to the second rectifier switch. The end of the first rectifier switch away from the bridge switch and the end of the second rectifier switch away from the bridge switch respectively constitute the positive output terminal and the negative output terminal. The dual resonant unit includes a first resonant unit and a second resonant unit, both composed of a resonant inductor and a DC blocking resonant capacitor connected in series. The first resonant unit is connected between the end of the upper bridge arm branch and the connection node of the bridging switch and the second rectifier switch. The second resonant unit is connected between the negative input terminal and the connection node of the first rectifier switch and the bridging switch. The two DC blocking resonant capacitors are used to block the continuous application of high voltage from the input bus to the output terminal when a drain-source breakdown short-circuit fault occurs in the primary-side power switch.

2. The fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 1, characterized in that, N is 8.

3. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 2, characterized in that, The four main switches in the upper bridge arm branch are sequentially named from the positive input terminal to the connection terminal between the upper and lower bridge arm branches: the first to the fourth switches. The four main switches in the lower bridge arm branch are sequentially named from the negative input terminal to the connection terminal: the fifth to the eighth switches. The three flying capacitors along the upper bridge arm branch from the positive input terminal to the connection terminal are sequentially named the first, second, and third flying capacitors. The converter includes three discrete buck modes: In the first discrete buck mode, the converter operates at a buck ratio of 4:1; In the second discrete buck mode, the converter operates at a buck ratio of 4:2; In the third discrete buck mode, the converter operates at a buck ratio of 4:

3.

4. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 3, characterized in that, In the first discrete buck mode, one switching cycle consists of eight sequentially occurring operating modes, denoted as mode 1a to mode 1h, specifically: Mode 1a: The first switch, the sixth switch, the seventh switch, the eighth switch and the bridge switch are turned on. The positive input terminal injects energy into the first flying capacitor through the first switch and forms a series resonant circuit with the dual resonant unit. Mode 1b: The discharge mode of mode 1a; the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 1c: The second, fifth, seventh, and eighth switches and the bridge switch are turned on, and energy is transferred from the first flying capacitor to the second flying capacitor, forming a series resonant circuit with the dual resonant unit; Mode 1d: is the discharge mode of mode 1c; its conduction topology is the same as that of mode 1b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 1e: The third, fifth, sixth, and eighth switches and the bridge switch are turned on, and energy is transferred from the second flying capacitor to the third flying capacitor, forming a series resonant circuit with the dual resonant unit. Mode 1f: the discharge mode of mode 1e; Its conduction topology is the same as that of mode 1b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 1g: The fourth, fifth, sixth, and seventh switches and the bridge switch are turned on, and the third flying capacitor releases energy to the resonant circuit as an energy source, forming a series resonant circuit with the dual resonant unit. Mode 1h: is the discharge mode of mode 1g; its conduction topology is the same as that of mode 1b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit.

5. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 3, characterized in that, In the second discrete buck mode, one switching cycle consists of four sequentially occurring operating modes, denoted as modes 2a to 2d. Modes 2a and 2c are two charging modes using complementary primary switch combinations, and modes 2b and 2d are the subsequent two discharging modes. The bridge switch is turned on during the two charging modes. Specifically: Mode 2a: The first switch, the second switch, the seventh switch, the eighth switch and the bridge switch are turned on. The positive input terminal injects energy into the second flying capacitor through the first switch and the second switch in series, and forms a series resonant circuit with the dual resonant unit. Mode 2b: The discharge mode of mode 2a; the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 2c: The third, fourth, fifth, and sixth switches and the bridge switch are turned on. The second flying capacitor participates in the resonant energy transfer again in a path that is symmetrical and complementary to that of mode 2a, and forms a series resonant circuit with the dual resonant unit. Mode 2d: the discharge mode of mode 2c; the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit.

6. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 3, characterized in that, In the third discrete buck mode, the timing structure of the third discrete buck mode is mirror-symmetric to that of the first discrete buck mode, and the energy transfer order is reversed compared to the first discrete buck mode. One switching cycle consists of eight sequentially occurring operating modes, denoted as modes 3a to 3h, where odd-numbered modes are charging modes and even-numbered modes are subsequent discharging modes. The bridging switch is turned on in each charging mode; specifically: Mode 3a: The first switch, the second switch, the third switch, the eighth switch and the bridge switch are turned on. The input power supply connected between the positive input terminal and the negative input terminal and the third flying capacitor are recombined to form an energy source, which forms a series resonant circuit with the dual resonant unit. Mode 3b: The discharge mode of mode 3a; the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 3c: The first switch, the second switch, the fourth switch, the seventh switch and the bridge switch are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the third flying capacitor and the second flying capacitor, form an energy source, which in turn forms a series resonant circuit with the dual resonant unit. Mode 3d: the discharge mode of mode 3c; Its conduction topology is the same as that of mode 3b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 3e: The first switch, the third switch, the fourth switch, the sixth switch and the bridge switch are turned on. The input power supply connected between the positive input terminal and the negative input terminal, together with the second flying capacitor and the first flying capacitor, recombines to form an energy source, and forms a series resonant circuit with the dual resonant unit. Mode 3f: is the discharge mode of mode 3e; Its conduction topology is the same as that of mode 3b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit; Mode 3g: The second, third, fourth, and fifth switches and the bridge switch are turned on, and the first flying capacitor alone serves as the energy source to complete the energy transfer, and forms a series resonant circuit with the dual resonant unit; Mode 3h: is the discharge mode of mode 3g; Its conduction topology is the same as that of mode 3b, that is, the fifth, sixth, seventh, eighth, first and second rectifier switches are turned on, and the resonant energy is released to the load through the secondary switching unit.

7. A fault-isolated multimode resonant DC-DC converter for a satellite power supply according to any one of claims 4 to 6, characterized in that, The first resonant unit and the second resonant unit reconstruct the charging and discharging circuit into a second-order underdamped resonant circuit. The conduction time of each working mode is matched with the resonant half-cycle of the corresponding equivalent resonant circuit, so that all power switching transistors perform commutation when the resonant current naturally crosses zero, thereby achieving zero-current soft switching.

8. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 1, characterized in that, The resonant inductor in the first resonant unit and the resonant inductor in the second resonant unit are not magnetically coupled to each other.

9. A fault-isolated multimode resonant DC-DC converter for satellite power supply according to claim 1, characterized in that, It also includes an input filter unit connected in parallel between the positive input terminal and the negative input terminal, and an output filter unit connected in parallel between the positive output terminal and the negative output terminal.

10. A modulation method for a fault-isolated multimode resonant DC-DC converter for a satellite power supply as described in claim 3, characterized in that, Includes the following steps: Step 1: Set the charging and discharging alternation timing: Within one switching cycle, make the converter alternate between charging mode and discharging mode, with each charging mode immediately followed by a discharging mode, and the conduction topology of each discharging mode is the same. Step 2: Execute charging mode: Control the bridge switch to turn on, connect the two resonant branches where the first resonant unit and the second resonant unit are located in series, and make the selected flying capacitor and the series resonant branch form a second-order underdamped resonant circuit, and the charging current is a sinusoidal half-wave. Step 3: Execute the discharge mode: Control the first rectifier switch and the second rectifier switch to be turned on, and turn off the first to fourth switches in the upper bridge arm branch, and turn on the fifth to eighth switches in the lower bridge arm branch, so that the energy stored in the dual resonant unit is released to the load through the secondary switch unit. Step 4: Switching the buck ratio: Switching between three discrete buck modes is achieved by reconstructing the series-parallel connection relationship between the first flying capacitor and the third flying capacitor by changing the conduction timing of each main switch, bridge switch, first rectifier switch, and second rectifier switch, so that the converter operates at one of the following three buck ratios, where m is the sequence number of the discrete buck mode, taking values ​​of 1, 2, and 3: When m=1, it corresponds to the 4:1 mode, V o =V in / 4; When m=2, it corresponds to the 4:2 mode, V o =V in / 2; When m=3, it corresponds to the 4:3 mode, V o =3V in / 4; Compare the input voltage with the preset mode switching threshold, and select the mode number m according to the comparison result so that the output voltage falls into the preset target range; Step 5: Implement zero-current soft switching: Set the conduction time of each operating mode according to the natural zero-crossing time of the resonant current, and reserve a zero-current margin so that all eleven power switching transistors can perform commutation when the resonant current naturally crosses zero.

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