An accelerator pulse power supply based on a PFC+LLC+H bridge chopper topology and a control method

Abstract

This invention relates to an accelerator pulse power supply and control method based on a PFC+LLC+H-bridge chopper topology, comprising: a PFC stage, an LLC stage, and an H-bridge chopper stage; the PFC stage employs a single-phase PWM rectifier structure, with its input connected to the AC power grid and its output connected to the input of the LLC stage, used to rectify the AC power input from the AC power grid and output a stable DC power; the LLC stage employs an LLC resonant converter structure, with its output connected to the input of the H-bridge chopper stage, used to reduce switching losses using soft-switching technology, while simultaneously achieving electrical isolation between the input and output sides and providing voltage conversion functionality; the output of the H-bridge chopper stage is connected to a magnetic load, used to adjust the output current according to preset requirements, outputting the required pulse current waveform. This invention can be widely applied in the field of particle accelerators.

Description

Technical Field

[0001] This invention belongs to the field of particle accelerators, specifically relating to an accelerator pulse power supply and control method based on a PFC (Power Factor Correction) + LLC (Resonant Converter) + H-bridge chopper topology, applicable to small and medium power pulse magnet power supplies for particle accelerator devices. Background Technology

[0002] Accelerator switching power supply topologies typically employ a front-stage rectifier + a rear-stage chopper topology. The primary purpose of the front-stage rectifier is to provide a DC voltage source that meets the power and voltage ripple requirements for the rear-stage chopper.

[0003] For unidirectional pulse power supplies, small to medium power pulse power supplies typically employ a two-stage structure consisting of a DC voltage source in the front stage and an H-bridge chopper in the rear stage. While this structure can achieve basic functionality, it has the following shortcomings in practical applications: On the one hand, the two-stage structure includes independent rectification and chopper circuits, with a large number of components. In order to meet the voltage ripple requirements, a large-capacity DC bus capacitor is required, which results in a large power supply system with a heavy weight. This also increases the cost of the power supply and limits the power density of the system.

[0004] On the other hand, after two stages of conversion, the power supply suffers significant losses, making it difficult to further improve the overall efficiency of the power supply. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide an accelerator pulse power supply and control method based on a PFC+LLC+H bridge chopper topology. This pulse power supply integrates front-stage rectification and rear-stage chopper, enabling energy recovery and utilization by feeding energy back to the grid during the load descent phase of the small-to-medium power pulse power supply. At the same time, it achieves miniaturization, light weight, high efficiency, and high performance of the pulse power supply, greatly reducing the cost of small-to-medium power pulse power supplies.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an accelerator pulse power supply based on a PFC+LLC+H bridge chopper topology, comprising: PFC-level, LLC-level and H-bridge chopper-level; The PFC stage adopts a single-phase PWM rectifier structure, and the input end of the single-phase PWM rectifier structure is connected to the AC power grid, and the output end is connected to the input end of the LLC stage, which is used to rectify the AC power input from the AC power grid and output stable DC power. The LLC stage adopts an LLC resonant converter structure, and the output terminal of the LLC resonant converter structure is connected to the input terminal of the H-bridge chopper stage. This is used to reduce switching losses using soft switching technology, while achieving electrical isolation between the input and output sides and providing voltage conversion function. The output terminal of the H-bridge chopper stage is connected to a magnetic load and is used to adjust the output current according to preset requirements, outputting the required pulse current waveform.

[0007] Furthermore, the single-phase PWM rectifier structure includes a first bridge arm and a second bridge arm; The first bridge arm is connected in series with a first switch and a second switch, the second bridge arm is connected in series with a third switch and a fourth switch, and the midpoint of the first bridge arm is connected to one end of the AC power grid through the AC equivalent resistance and AC inductance, and the midpoint of the second bridge arm is connected to the other end of the AC power grid. The two ends of the first bridge arm and the second bridge arm are connected in parallel and then connected to the input terminal of the LLC stage via the first output filter capacitor.

[0008] Furthermore, the LLC resonant converter structure includes a full-bridge inverter, a resonant structure, a synchronous rectifier, and an ideal transformer; The full-bridge inverter includes a third bridge arm and a fourth bridge arm. A fifth switch and a sixth switch are connected in series on the third bridge arm, and a seventh switch and an eighth switch are connected in series on the fourth bridge arm. The resonant structure, consisting of a resonant capacitor, a resonant inductor, and a transformer magnetizing inductor, is connected at the midpoint of the third bridge arm to the midpoint of the fourth bridge arm; the two ends of the third and fourth bridge arms are connected in parallel with the output of the PFC stage as input terminals; The synchronous rectifier includes a fifth bridge arm and a sixth bridge arm. A ninth switch and a tenth switch are connected in series on the fifth bridge arm, and an eleventh switch and a twelfth switch are connected in series on the sixth bridge arm. The ideal transformer is positioned between the full-bridge inverter and the synchronous rectifier, with its primary winding connected in parallel with the transformer magnetizing inductor, and its secondary winding connected to the midpoints of the fifth and sixth bridge arms. The two ends of the fifth and sixth bridge arms serve as output terminals and are connected to the input terminals of the H-bridge chopper stage via a second output filter capacitor.

[0009] Furthermore, the H-bridge chopper stage includes a seventh bridge arm and an eighth bridge arm. A thirteenth and fourteenth switch are connected in series on the seventh bridge arm, and a fifteenth and sixteenth switch are connected in series on the eighth bridge arm. A load resistor and a load inductor are connected between the midpoint of the seventh bridge arm and the midpoint of the eighth bridge arm.

[0010] Secondly, the present invention provides a control method for an accelerator pulse power supply based on a PFC+LLC+H bridge chopper topology, comprising: Based on a given reference voltage, a dual closed-loop control strategy consisting of an outer voltage loop and an inner current loop is employed to control the PFC stage, ensuring a stable DC bus voltage output. V c1 ; Based on pre-determined key resonance parameters, the switching frequency and the turns ratio of the ideal transformer are determined according to the bus voltage and resonant frequency, so that the LLC stage outputs a stable DC voltage. V c2 ; A current loop closed-loop control strategy is adopted to control the H-bridge chopper stage and output the pulse current waveform required by the magnetic load.

[0011] Furthermore, based on a given reference voltage, a dual closed-loop control strategy consisting of an outer voltage loop and an inner current loop is used to control the PFC stage, enabling it to output a stable DC bus voltage. V c1 ,include: ①Based on a given reference voltage and the DC bus voltage output by the current PFC stage The amplitude reference current of the inner current loop is calculated using the first voltage loop PI compensator. ; ②Based on amplitude reference current Sinusoidal reference angle of grid voltage Calculated current reference ; ③ Based on current reference and current The modulation signal of the switching transistor in the PFC stage is calculated using the first current loop PI compensator. ④ Based on the modulation signal of the switching transistor in the PFC stage, the drive signal of each switching transistor is calculated using the first SPWM modulator and used to control the PFC stage. ⑤ Repeat steps ① to ④ above until a stable DC bus voltage is output. .

[0012] Furthermore, based on pre-determined key resonance parameters, the switching frequency and the turns ratio of the ideal transformer are determined according to the bus voltage and resonant frequency, enabling the LLC stage to output a stable DC voltage. V c2 ,include: Based on a given reference voltage and the DC bus voltage of the current LLC stage output The desired frequency is calculated using the second voltage loop PI compensator. ; Based on DC bus voltage And the maximum output power, to determine the key resonance parameters; Determine the control strategy for the ideal transformer and set the desired frequency. After passing through a limiter, the signal is fed into a voltage-controlled oscillator (VCO). The VCO outputs drive pulses of different frequencies but with a fixed duty cycle according to the magnitude of the input value, thereby controlling the LLC stage.

[0013] Furthermore, the current loop closed-loop control strategy is used to control the H-bridge chopper stage and output the pulse current waveform required by the magnetic load, including: Based on the given output current reference and the current output current of the H-bridge chopper pole The modulation signal of the switching transistor of the H-bridge chopper stage is calculated using the second current loop PI compensator. Based on the modulation signal of the switching transistors of the H-bridge chopper stage, the drive signal of each switching transistor is calculated by the second SPWM modulator and used to control the H-bridge chopper stage. The output current of the H-bridge chopper stage After being filtered by an LC filter, the load resistance and load inductance are output to the magnet. The present invention has the following advantages due to the adoption of the above technical solutions: 1. This invention achieves high power factor and is grid-friendly through a three-level topology; the LLC stage operates in soft-switching mode, achieving high efficiency of the entire system; the H-bridge converter operates in high-frequency PWM mode, with high control bandwidth, which can effectively suppress output voltage fluctuations.

[0014] 2. This invention ensures that SiC MOSFET devices operate in a safe operating region, thereby enabling high-frequency and miniaturized pulse power supplies, and guaranteeing high-density power and high efficiency.

[0015] 3. The topology proposed in this invention can be extended to a three-phase power unit and used as a standardized module to realize the series and parallel connection of multiple modules. It can flexibly realize the power level expansion and configuration and can be widely used in small and medium power pulse power supplies.

[0016] This invention can be widely applied in the field of particle accelerators. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the main topology principle of the accelerator pulse power supply based on the PFC+LLC+H bridge chopper topology provided in the embodiment of the present invention. Figure 2 This is a schematic diagram of the accelerator pulse power supply module provided in an embodiment of the present invention; Figure 3 This is a control block diagram of the PFC level provided in an embodiment of the present invention; Figure 4 This is a control block diagram of LLC level provided in an embodiment of the present invention; Figure 5 This is a control block diagram of the H-bridge chopper stage provided in an embodiment of the present invention; Figure 6 This is the simulation result of the entire pulse cycle in an embodiment of the present invention; Figure 7 This is the output test result for the entire pulse cycle of this invention embodiment. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] In some embodiments of this invention, an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology is provided. By integrating the front-stage rectification and the rear-stage chopper into one unit, all the energy required during the rising phase of the current waveform pulse is provided by the front stage; during the falling phase of the current waveform, the energy stored in the magnetic load inductor is fed back to the grid side, achieving energy reuse. This invention achieves a high power factor and is grid-friendly through a three-stage topology; the LLC stage operates in a soft-switching state, achieving high efficiency for the entire system; the H-bridge converter operates in a high-frequency PWM state, with a high control bandwidth, which can effectively suppress output voltage fluctuations.

[0021] Correspondingly, in other embodiments of the present invention, a control method for an accelerator pulse power supply based on a PFC+LLC+H bridge chopper topology is also provided.

[0022] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0023] Example 1 like Figure 1 As shown, this embodiment provides an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology, comprising a PFC stage, an LLC stage, and an H-bridge chopper stage. The PFC stage employs a single-phase PWM rectifier structure, with its input connected to the AC power grid and its output connected to the input of the LLC stage. This rectifies the AC power input from the AC power grid to output a stable DC power, achieving unity power factor correction (PFC) and low current harmonic distortion (THD). The LLC stage employs an LLC resonant converter structure, with its output connected to the input of the H-bridge chopper stage. This utilizes soft-switching technology to reduce switching losses, achieves electrical isolation between the input and output sides, and provides voltage conversion functionality. The output of the H-bridge chopper stage is connected to a magnetic load, used to adjust the output current according to preset requirements, outputting the desired pulse current waveform.

[0024] Furthermore, the single-phase PWM rectifier structure includes a first bridge arm and a second bridge arm, with a first switching transistor S connected in series on the first bridge arm. 11 Second switch S 12 A third switch S is connected in series on the second bridge arm. 13 and the fourth switch S 14 The midpoint of the first bridge arm is connected to one end of the AC power grid through the AC equivalent resistance R and the AC inductance L, and the midpoint of the second bridge arm is connected to the other end of the AC power grid; the two ends of the first bridge arm and the second bridge arm are connected in parallel and then connected to the input terminal of the LLC stage through the first output filter capacitor C1.

[0025] Furthermore, the LLC resonant converter structure includes a full-bridge inverter, a resonant structure, a synchronous rectifier, and an ideal transformer T. r1 The full-bridge inverter includes a third bridge arm and a fourth bridge arm, with a fifth switching transistor S connected in series on the third bridge arm. 21 and the sixth switch S 22 The seventh switch S is connected in series on the fourth bridge arm. 23and the eighth switch S 24 The midpoint of the third bridge arm is connected to the resonant capacitor C. r Resonant inductor L r and transformer magnetizing inductance L m The resonant structure is connected to the midpoint of the fourth bridge arm; the ends of the third and fourth bridge arms are connected in parallel with the output of the PFC stage; the synchronous rectifier includes the fifth and sixth bridge arms, with the ninth switch S connected in series on the fifth bridge arm. 25 and the tenth switch S 26 The eleventh switch S is connected in series on the sixth bridge arm. 27 and the twelfth switch S 28 Ideal transformer T r1 The actual transformer is equivalent to a transformer with a turns ratio of N, located between the full-bridge inverter and the synchronous rectifier, and the ideal transformer T... r1 The primary side and the transformer magnetizing inductance L m Parallel connection, ideal transformer T r1 The secondary side is connected to the midpoint of the fifth bridge arm and the midpoint of the sixth bridge arm; the two ends of the fifth and sixth bridge arms are connected to the input of the H-bridge chopper stage via the second output filter capacitor C2.

[0026] In this embodiment, the LLC stage adopts an isolated resonant converter structure. By utilizing resonant soft-switching technology, it can greatly reduce switching losses and achieve high-frequency isolation and high-efficiency power transmission. At the same time, operating at high frequency can reduce the size of transformers and filter components, achieve electrical isolation between the input and output sides, and provide voltage conversion functions.

[0027] Furthermore, the H-bridge chopper stage includes a seventh arm and an eighth arm, with a thirteenth switch S connected in series on the seventh arm. 31 and the fourteenth switch S 32 The fifteenth switch S is connected in series on the eighth bridge arm. 33 and the sixteenth switch S 34 A load resistor R is connected between the midpoint of the seventh bridge arm and the midpoint of the eighth bridge arm. L and load inductance L L .

[0028] Furthermore, the topology in this invention uses only a single-phase power unit as an example, but it can be expanded into a three-phase power unit, with the AC grid inputs connected in the order of A / B, B / C, and C / A. This achieves power expansion while avoiding three-phase power imbalance and tolerating phase-to-phase input voltage imbalance.

[0029] Furthermore, the first to sixteenth switching transistors all adopt SiC MOSFET devices. By ensuring that the SiC MOSFET devices operate in a safe operating range, the power module can be made more frequent and smaller, thus ensuring high power density and high efficiency.

[0030] Furthermore, such as Figure 2 As shown, the PFC stage, LLC stage, and H-bridge chopper stage in this invention can be considered as standardized modules, supporting multiple modules in series or parallel connection to achieve flexible expansion and redundant configuration of power levels. The standardized module design not only improves the reliability and maintainability of the equipment but also provides a quickly reusable platform solution for different accelerator pulse power supply applications. The converter can meet the needs of small and medium power accelerator pulse power supplies and has the ability to expand to larger power systems.

[0031] In this invention, the energy required for the rising phase of the current waveform pulse is entirely provided by the preceding stage; during the falling phase of the current waveform, the energy stored in the magnetic load inductor is fed back to the grid side, achieving energy reuse. This topology integrates the preceding rectifier voltage source and the subsequent chopper, specifically addressing the problems of large size, low efficiency, and high cost in pulse power supplies for small and medium-power particle accelerators.

[0032] Example 2 Based on the accelerator pulse power supply based on the PFC+LLC+H bridge chopper topology provided in Embodiment 1, this embodiment provides a control method for the accelerator pulse power supply based on the PFC+LLC+H bridge chopper topology. By adopting a three-level control strategy, high-precision pulse current output is achieved.

[0033] Specifically, it includes the following steps: 1) Based on a given reference voltage, a dual closed-loop control strategy consisting of an outer voltage loop and an inner current loop is used to control the PFC stage, ensuring a stable DC bus voltage output. V c1 ; 2) Based on pre-determined key resonance parameters, the switching frequency and the turns ratio of the ideal transformer are determined according to the bus voltage and resonant frequency, so that the LLC stage outputs a stable DC voltage. V c2 ; 3) A current loop closed-loop control strategy is adopted to control the H-bridge chopper stage and output the pulse current waveform required by the magnet load.

[0034] Furthermore, in step 1) above, such as Figure 3 The diagram shown is the control block diagram for the PFC stage. The control strategy for this stage adopts a dual closed-loop control with an outer voltage loop and an inner current loop, and introduces grid voltage feedforward.

[0035] Specifically, it includes the following steps: 1.1) Based on a given reference voltage and the DC bus voltage output by the current PFC stage (That is, the feedback voltage), the amplitude reference current of the inner current loop is calculated using the first voltage loop PI compensator. ; 1.2) Based on amplitude reference current Sinusoidal reference angle of grid voltage Calculated current reference Among them, the sinusoidal reference angle of the grid voltage It is the grid voltage phase angle obtained using a single-phase phase-locked loop (PLL); 1.3) Based on current reference and current The modulation signal of the switching transistor in the PFC stage is calculated using the first current loop PI compensator. 1.4) Based on the modulation signal of the switching transistor in the PFC stage, the S of the first switching transistor is calculated using the first SPWM modulator. 11 The second switch S 12 The third switch S 13 Fourth switch S 14 The drive signal is used to control the PFC stage; 1.5) Repeat steps 1.1) to 1.4) above until a stable DC bus voltage is output. .

[0036] In this embodiment, the outer voltage loop stabilizes the DC bus voltage through a first voltage loop PI compensator. Its output serves as the amplitude reference for the inner current loop. . It directly determines the direction of energy flow: when Higher than the reference value hour, When the value is negative, the PWM rectifier operates in inverter mode, feeding energy back to the AC grid; when... When it is below the reference value, When the signal is positive, the PWM rectifier operates in rectification mode, absorbing energy from the AC grid. Grid voltage feedforward can effectively suppress the interference of grid background harmonics on the quality of the incoming current.

[0037] Furthermore, in step 2) above, such as Figure 4 As shown, LLC-level control includes the following steps: 2.1) Based on a given reference voltage and the DC bus voltage of the current LLC stage output (That is, the feedback voltage), the desired frequency is calculated using the second voltage loop PI compensator. ; 2.2) Based on the DC bus voltage And the maximum output power, determine key resonance parameters such as resonant frequency, resonant inductance, resonant capacitance, magnetizing inductance, and turns ratio of the ideal transformer; The method for determining the key parameters of resonance is a well-known technique in the field, and will not be elaborated upon in this invention. 2.3) Determine the control strategy for the ideal transformer, and set the desired frequency... After passing through a limiter, the signal is fed into a voltage-controlled oscillator (VCO). The VCO outputs drive pulses of different frequencies but with a fixed duty cycle according to the magnitude of the input value, thereby controlling the LLC stage.

[0038] In this design, the secondary side of the ideal transformer employs a synchronous rectification strategy, while the primary side uses a single-voltage loop frequency modulation control strategy. The output voltage is regulated by changing the operating frequency. When the LLC converter operates in the forward direction, it can achieve buck-boost operation by changing the operating frequency, exhibiting a wide gain range. When the LLC converter operates in the reverse direction, it is equivalent to an LC series resonant converter, enabling buck operation.

[0039] Furthermore, in step 3) above, such as Figure 5 As shown, the H-bridge chopper stage control includes the following steps: 3.1) Based on a given output current reference and the current output current of the H-bridge chopper pole (That is, feedback current), the modulation signal of the switching transistor of the H-bridge chopper stage is calculated using the second current loop PI compensator. 3.2) Based on the modulation signal of the switching transistor of the H-bridge chopper stage, the switching transistor S is calculated using the second SPWM modulator. 31 S 32 ,S 33 ,S 34 The drive signal is used to control the H-bridge chopper stage; 3.3) Output current of the H-bridge chopper stage After being filtered by an LC filter, the load resistance and load inductance are output to the magnet.

[0040] In this embodiment, the control of the accelerator pulse power supply adopts a hierarchical decoupling approach to reduce the increased control complexity caused by mutual interference between different control stages. Specifically, the PFC stage and LLC stage control the output voltage, while the H-bridge chopper stage controls the output current to produce the pulsed current waveform required by the load. The PFC stage output provides the preceding voltage to the LLC stage; the LLC stage output provides the preceding voltage to the H-bridge chopper topology; and the H-bridge chopper topology provides the pulsed current to the load. The control strategies for the first two voltage stages are decoupled and controlled separately. The control methods for the H-bridge chopper stage and LLC stage are also independent.

[0041] Example 3 This embodiment uses a pulsed power supply for a heavy ion accelerator as an example, with an output current peak of 100A and a current rise rate of 100A / s. For a single-phase module with a rated power of 6kW and a mains voltage of 220V / 50Hz, the PFC output is rectified by a single-phase PWM converter to output DC voltage. V c1 The input voltage of the LLC circuit is 750V, the output voltage is 600V, and the switching frequency is 120kHz. The transformer ratio is 5:4, the primary voltage is 750V, and the secondary voltage is 600V; the LLC circuit uses two types of SiC MOSFETs on the primary and secondary sides, with a switching frequency of 120kHz.

[0042] When the pulse power supply is in the current drop phase, the energy of the magnetic load is fed back to the front stage of the topology. The front stage PWM rectifier starts to invert, and the energy flows to the grid. The relationship between the grid-side voltage and current also changes from in phase to 180° out of phase.

[0043] like Figure 6 and Figure 7 The figures show the simulation and measured results of the grid-side voltage and current waveforms and the output current waveforms with energy feedback under the condition of voltage overshoot, respectively, which verify the effectiveness of bidirectional energy flow.

[0044] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology, characterized in that, include: PFC-class, LLC-class, and H-bridge chopper-class; The PFC stage adopts a single-phase PWM rectifier structure, and the input end of the single-phase PWM rectifier structure is connected to the AC power grid, and the output end is connected to the input end of the LLC stage, which is used to rectify the AC power input from the AC power grid and output stable DC power. The LLC stage adopts an LLC resonant converter structure, and the output terminal of the LLC resonant converter structure is connected to the input terminal of the H-bridge chopper stage. This is used to reduce switching losses using soft switching technology, while achieving electrical isolation between the input and output sides and providing voltage conversion function. The output terminal of the H-bridge chopper stage is connected to a magnetic load and is used to adjust the output current according to preset requirements, outputting the required pulse current waveform.

2. The accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 1, characterized in that, The single-phase PWM rectifier structure includes a first bridge arm and a second bridge arm. The first bridge arm is connected in series with a first switch and a second switch, the second bridge arm is connected in series with a third switch and a fourth switch, and the midpoint of the first bridge arm is connected to one end of the AC power grid through the AC equivalent resistance and AC inductance, and the midpoint of the second bridge arm is connected to the other end of the AC power grid. The two ends of the first bridge arm and the second bridge arm are connected in parallel and then connected to the input terminal of the LLC stage via the first output filter capacitor.

3. An accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 1, characterized in that, The LLC resonant converter structure includes a full-bridge inverter, a resonant structure, a synchronous rectifier, and an ideal transformer; The full-bridge inverter includes a third bridge arm and a fourth bridge arm. A fifth switch and a sixth switch are connected in series on the third bridge arm, and a seventh switch and an eighth switch are connected in series on the fourth bridge arm. The resonant structure, consisting of a resonant capacitor, a resonant inductor, and a transformer magnetizing inductor, is connected at the midpoint of the third bridge arm to the midpoint of the fourth bridge arm; the two ends of the third and fourth bridge arms are connected in parallel with the output of the PFC stage as input terminals; The synchronous rectifier includes a fifth bridge arm and a sixth bridge arm. A ninth switch and a tenth switch are connected in series on the fifth bridge arm, and an eleventh switch and a twelfth switch are connected in series on the sixth bridge arm. The ideal transformer is positioned between the full-bridge inverter and the synchronous rectifier, with its primary winding connected in parallel with the transformer magnetizing inductor, and its secondary winding connected to the midpoints of the fifth and sixth bridge arms. The two ends of the fifth and sixth bridge arms serve as output terminals and are connected to the input terminals of the H-bridge chopper stage via a second output filter capacitor.

4. An accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 1, characterized in that, The H-bridge chopper stage includes a seventh bridge arm and an eighth bridge arm. A thirteenth and fourteenth switch are connected in series on the seventh bridge arm, and a fifteenth and sixteenth switch are connected in series on the eighth bridge arm. A load resistor and a load inductor are connected between the midpoint of the seventh bridge arm and the midpoint of the eighth bridge arm.

5. A control method for an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in any one of claims 1 to 4, characterized in that, include: Based on a given reference voltage, a dual closed-loop control strategy consisting of an outer voltage loop and an inner current loop is employed to control the PFC stage, ensuring a stable DC bus voltage output. V c1 ; Based on pre-determined key resonance parameters, the switching frequency and the turns ratio of the ideal transformer are determined according to the bus voltage and resonant frequency, so that the LLC stage outputs a stable DC voltage. V c2 ; A current loop closed-loop control strategy is adopted to control the H-bridge chopper stage and output the pulse current waveform required by the magnetic load.

6. The control method for an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 5, characterized in that, Based on a given reference voltage, a dual closed-loop control strategy consisting of an outer voltage loop and an inner current loop is used to control the PFC stage, ensuring that it outputs a stable DC bus voltage. V c1 ,include: ①Based on a given reference voltage and the DC bus voltage output by the current PFC stage The amplitude reference current of the inner current loop is calculated using the first voltage loop PI compensator. ; ②Based on amplitude reference current Sinusoidal reference angle of grid voltage Calculated current reference ; ③ Based on current reference and current The modulation signal of the switching transistor in the PFC stage is calculated using the first current loop PI compensator. ④ Based on the modulation signal of the switching transistor in the PFC stage, the drive signal of each switching transistor is calculated using the first SPWM modulator and used to control the PFC stage. ⑤ Repeat steps ① to ④ above until a stable DC bus voltage is output. .

7. The control method for an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 5, characterized in that, Based on pre-determined key resonance parameters, the switching frequency and the turns ratio of the ideal transformer are determined according to the bus voltage and resonant frequency, enabling the LLC stage to output a stable DC voltage. V c2 ,include: Based on a given reference voltage and the DC bus voltage of the current LLC stage output The desired frequency is calculated using the second voltage loop PI compensator. ; Based on DC bus voltage And the maximum output power, to determine the key resonance parameters; Determine the control strategy for the ideal transformer and set the desired frequency. After passing through a limiter, the signal is fed into a voltage-controlled oscillator (VCO). The VCO outputs drive pulses of different frequencies but with a fixed duty cycle according to the magnitude of the input value, thereby controlling the LLC stage.

8. The control method for an accelerator pulse power supply based on a PFC+LLC+H-bridge chopper topology as described in claim 5, characterized in that, The method employs a current loop closed-loop control strategy to control the H-bridge chopper stage and output the pulse current waveform required by the magnetic load, including: Based on the given output current reference and the current output current of the H-bridge chopper pole The modulation signal of the switching transistor of the H-bridge chopper stage is calculated using the second current loop PI compensator. Based on the modulation signal of the switching transistors of the H-bridge chopper stage, the drive signal of each switching transistor is calculated by the second SPWM modulator and used to control the H-bridge chopper stage. The output current of the H-bridge chopper stage After being filtered by an LC filter, the load resistance and load inductance are output to the magnet.

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