High-power three-level power supply module with LLC resonant soft switch

Abstract

The invention discloses a high-power three-level power supply module with an LLC resonant soft switch, and relates to the technical field of power electronics, the power supply module comprises an alternating current switch, a transformer, a three-phase controllable rectification circuit, a three-level inverter, a boosting transformer and an uncontrolled rectification circuit which are connected in sequence, and the three-level inverter is internally provided with an LLC resonant circuit; the LLC resonant circuit comprises three resonant branches which are connected with one another, and is used for shaping and filtering the output voltage and the output current, and enabling a switching device in the power supply module to be switched on and / or switched off under a zero-voltage or zero-current condition; the efficiency of the ion cyclotron three-level high-voltage power supply system is improved and the switching stress is reduced, so that the ion cyclotron high-voltage power supply can realize zero-voltage switching or zero-current switching through a resonance phenomenon compared with a three-level power supply module without a soft switching technology, the switching loss of a switching device is greatly reduced, and the overall efficiency of the power supply is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, more particularly, it relates to a high-power three-level power supply module with LLC resonant soft switching. BACKGROUND

[0002] In the operation process of a nuclear fusion device, different physical experiment stages and plasma states may require different ion cyclotron resonance heating powers, and thus different high-voltage power supply output voltages; a three-level inverter type high-voltage power supply can well adapt to such a requirement, and can quickly adjust from a lower voltage output to a higher voltage output to meet the situation of rapid plasma temperature rise or current driving strength change, thereby providing a strong guarantee for flexible experiment development.

[0003] The switching devices of the three-level inverter change relatively small in voltage during the switching operation. Compared with the PSM (pulse step modulation) high-voltage power supply, the voltage stress borne by the device is reduced during each switching operation of the three-level inverter. The output waveform of the PSM high-voltage power supply is often composed of a series of pulse steps, and the waveform quality is relatively poor. In actual application, such a pulse step waveform may cause harmonic interference. In addition, the controllable devices of the three-level inverter type high-voltage power supply are all at the low voltage end, so that the electric field and stress borne by the switching device during protection are reduced. Therefore, it is of great significance to study the three-level high-voltage power supply.

[0004] The ion cyclotron three-level high-voltage power supply is realized by series connection of several three-level power supply modules to obtain the final DC high-voltage output, and the power of a single power supply module is about several hundred kilowatts to megawatts. The switching frequency of the power supply module is relatively high, generally about several kilohertz, and if the commonly used three-level switching technology is used, a large amount of power loss will occur during the turn-on and turn-off processes. Therefore, corresponding topological structures and control measures must be used to reduce power loss and improve efficiency. In some common cases of implementing soft switching technology, the LLC resonant soft switching technology is included, and the common voltage range is several hundred volts, and some small-power power supply modules are several kilowatts. In the medium-power field, the common power is 10kW-30kW, for example, the power of some charging pile modules is designed to be 20kW-30kW. In high-power applications, it can also reach several tens of kilowatts to hundreds of kilowatts. At present, there is no much research on the LLC resonant soft switching technology for high-power power supply modules of several hundred kilowatts to megawatts.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The application aims to provide a large-power three-level power module with LLC resonance soft switching, so as to improve the efficiency of an ion cyclotron three-level high-voltage power supply system and reduce switching stress, and make the ion cyclotron high-voltage power supply realize zero-voltage switching or zero-current switching through resonance, greatly reduce switching loss of switching devices, and improve the overall efficiency of the power supply.

[0007] The above technical purpose of the application is achieved by the following technical scheme: In a first aspect, the application provides a large-power three-level power module with LLC resonance soft switching, comprising an AC switch, a transformer, a three-phase controllable rectifier circuit, a three-level inverter, a step-up transformer and a non-controlled rectifier circuit connected in sequence, wherein: The three-level inverter is provided with an LLC resonance circuit, and the input end of the LLC resonance circuit is connected to the step-up transformer; the LLC resonance circuit comprises three resonance branches connected to each other, and is used for shaping and filtering output voltage and output current, and making switching devices in the power module turn on and / or turn off under zero voltage or zero current conditions.

[0008] On the basis of the above technical scheme, the application can be further improved as follows.

[0009] Further, the AC switch is an input control component of the power module, the input end of the AC switch is connected to an external AC power supply, the output end of the AC switch is connected to the transformer, and the AC switch is used for connecting or disconnecting the external AC power supply.

[0010] Further, the output end of the transformer is connected to the input end of the three-phase controllable rectifier circuit, and is used for increasing or decreasing the input AC voltage to a voltage value processed by the three-phase controllable rectifier circuit.

[0011] Further, the three-phase controllable rectifier circuit is used for rectifying and filtering the three-phase AC output by the transformer, and converting the three-phase AC into DC, and the voltage of the output DC is regulated by controllable rectifier devices in the circuit.

[0012] Further, the input end of the three-level inverter is connected to the output end of the three-phase controllable rectifier circuit, which is used for reducing the voltage stress of the switching devices in the power module, and for converting the DC output by the three-phase controllable rectifier circuit into AC.

[0013] Further, the input end of the step-up transformer is connected to the output end of the three-level inverter, and is used for increasing the AC output by the three-level inverter to a required voltage value.

[0014] Further, the input end of the boost transformer is connected to the output end of the three-level inverter, and is used to raise the AC voltage output by the three-level inverter to a required voltage value.

[0015] Further, the resonant branch comprises a first diode, a second diode, a first fully-controlled switching device, a second fully-controlled switching device, a third fully-controlled switching device, a fourth fully-controlled switching device, a resonant inductor and a resonant capacitor, wherein: The emitter of the first fully-controlled switching device is connected to the collector of the second fully-controlled switching device, the emitter of the second fully-controlled switching device is connected to the collector of the third fully-controlled switching device, the emitter of the third fully-controlled switching device is connected to the collector of the fourth fully-controlled switching device, and the collector of the first fully-controlled switching device and the emitter of the fourth fully-controlled switching device are respectively connected to the positive and negative output ends of the three-phase controllable rectifier circuit. The emitter of the third fully-controlled switching device is connected to the input end of the first diode, the output end of the first diode is connected to the input end of the second diode, and the output end of the second diode is connected to the collector of the second fully-controlled switching device. The emitter of the second fully-controlled switching device is connected to one end of the resonant inductor, the other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one of the input interfaces of the boost transformer.

[0016] Further, the input ends of the first diodes in the three resonant branches are connected to each other, and are further connected between the upper end capacitor and the lower end capacitor of the three-phase rectifier circuit.

[0017] In a second aspect, the application provides an application of a high-power three-level power supply module with LLC resonant soft switching in a direct current power supply scene.

[0018] Compared with the prior art, the application has at least the following beneficial effects: 1. The LLC resonant soft switching technology can reduce the switching loss caused by the voltage and current overlap in the switching process, so that high-efficiency energy conversion can be maintained at a high frequency, and the rate of change of the voltage or current of the switching device is low, reducing the generation of electromagnetic interference.

[0019] 2. The resonant network composed of the inductor and the capacitor can efficiently transfer energy between the inductor and the capacitor in the resonant state, reducing the loss of energy in the transmission process and improving the overall conversion efficiency.

[0020] 3. By adjusting the working frequency, the LLC resonant converter can maintain high efficiency under a wide range of load changes without relying on a complex control system, and can well adapt to the change of the output voltage whether in a light load or a heavy load.

[0021] 4. The DC input voltage of the three-level inverter is regulated by the three-phase uncontrolled rectifier circuit, and in combination with the three-level output voltage regulation, the output voltage can be regulated in a wider range to meet the requirement of different heating power of the ion cyclotron system in different physical experiment stages and plasma states. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings: Figure 1 It is a schematic diagram of the main circuit of the high-power three-level power module in the embodiments of the application. Figure 2 It is a schematic diagram of the three-phase neutral point clamped inverter with LLC resonant soft switching in the embodiments of the application.

[0023] Markings in the drawings and corresponding names of parts: 1. AC switch; 2. Transformer; 3. Three-phase rectifier circuit; 4. Three-level inverter; 5. Step-up transformer; 6. Uncontrolled rectifier circuit; 7. Upper end capacitor; 8. Lower end capacitor; 9. Resonant inductor; 10. Resonant capacitor; 11. Fully controlled switching device; 12. Diode. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. The components of the embodiments of the application described and shown in the drawings can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the protection of the application.

[0026] It should be noted that: similar labels and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0028] Furthermore, the use of terms such as "horizontal," "vertical," and "overhanging" does not necessarily imply that the component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0029] In the description of the embodiments of the present invention, "a plurality of" means at least two.

[0030] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] Example 1: Since there is not much research on LLC resonant soft switching technology for high-power power modules ranging from several hundred kilowatts to megawatts, this embodiment provides a high-power three-level power module with LLC resonant soft switching to improve the efficiency of the ion cyclotron three-level high-voltage power supply system and reduce switching stress. Compared with the three-level power supply module without soft switching technology, the ion cyclotron high-voltage power supply can achieve zero voltage switching or zero current switching through the resonance phenomenon, which greatly reduces the switching loss of the switching device and improves the overall efficiency of the power supply. Figure 1 As shown, this high-power three-level power module: The power supply module comprises an AC switch 1, a transformer 2, a three-phase controlled rectifier circuit, a three-level inverter 4, a step-up transformer 5, and an uncontrolled rectifier circuit 6, which are connected in sequence. An LLC resonant circuit is provided in the three-level inverter 4, and the input end of the LLC resonant circuit is connected to the step-up transformer 5. The LLC resonant circuit comprises three interconnected resonant branches and is used to shape and filter the output voltage and output current, and to turn on and / or off the switching devices in the power supply module under zero voltage or zero current conditions.

[0032] The AC switch 1 is an input control component of the power module, the input end of the AC switch 1 is connected with an external AC power supply, the output end of the AC switch 1 is connected with the transformer 2, and the AC switch 1 is used for connecting or disconnecting the external AC power supply.

[0033] The output end of the transformer 2 is connected with the input end of the three-phase controllable rectifier circuit, and is used for increasing or decreasing the input AC power to a voltage value processed by the three-phase controllable rectifier circuit.

[0034] The three-phase controllable rectifier circuit is used for rectifying and filtering the three-phase AC power output by the transformer 2, and converting the three-phase AC power into DC power, and the voltage of the output DC power is regulated by the controllable rectifier device in the three-phase controllable rectifier circuit.

[0035] The input end of the three-level inverter 4 is connected with the output end of the three-phase controllable rectifier circuit, is used for reducing the voltage stress of the switching device in the power module, and is used for converting the DC power output by the three-phase controllable rectifier circuit into AC power.

[0036] Further, the input end of the step-up transformer 5 is connected with the output end of the three-level inverter 4, and is used for increasing the AC power output by the three-level inverter 4 to a required voltage value.

[0037] Further, the input end of the step-up transformer 5 is connected with the output end of the three-level inverter 4, and is used for increasing the AC power output by the three-level inverter 4 to a required voltage value.

[0038] Specifically, when the LLC resonant soft switching technology is implemented in a high-power power module (hundreds of kilowatts to megawatts), the following problems and challenges exist: 1. At high voltage (hundreds of volts to kilovolts) and large current, the conduction loss and switching loss of the switching device (IGBT) increase significantly, and the ZVS range is easily affected by load fluctuations; at the same time, the magnetic core loss and copper loss of the transformer 2 and the inductor increase nonlinearly with the increase of power, which may cause overheating; 2. In a high-power scenario, the influence of distributed parameters (such as transformer 2 leakage inductance and line parasitic capacitance) on the resonant network is intensified, and accurate modeling is required to avoid resonant frequency deviation and soft switching failure; when the load range is wide (such as 0%-100%), traditional frequency conversion control may cause excessive frequency fluctuation, affecting the design of magnetic components and system stability; 3. The increase of power density of a single module will lead to a sharp increase in cooling cost, and the energy release is rapid when a high-power fault occurs, so a fast protection circuit (such as short-circuit current limiting and over-temperature protection) needs to be designed to avoid device damage and chain failure.

[0039] To this end, this embodiment introduces phase-shifted PWM control on the basis of traditional LLC variable frequency control. By adjusting the phase difference of the primary-side switching tube, the voltage regulation range is expanded while maintaining the ZVS condition. For example, variable frequency control is mainly used under light load, while phase-shift control is combined under heavy load to avoid core saturation caused by too low frequency.

[0040] Optionally, the resonant branch includes a first diode, a second diode, a first fully controlled switch device, a second fully controlled switch device, a third fully controlled switch device, a fourth fully controlled switch device, a resonant inductor 9 and a resonant capacitor 10, as shown in FIG. Figure 2 As shown, in Figure 2 In the figure, reference numeral 11 represents a fully controlled switching device 11 (each resonant branch includes four fully controlled switching devices 11, according to Figure 2 Arranged from top to bottom, they are described as the first fully controlled switching device, the second fully controlled switching device, the third fully controlled switching device, and the fourth fully controlled switching device. Reference numeral 12 represents a diode 12 (each resonant branch includes two diodes 12, according to FIG. Figure 2 From bottom to top, they are represented as the first diode and the second diode respectively), where: The emitter of the first fully-controlled switching device is connected to the collector of the second fully-controlled switching device, the emitter of the second fully-controlled switching device is connected to the collector of the third fully-controlled switching device, the emitter of the third fully-controlled switching device is connected to the collector of the fourth fully-controlled switching device, and the collector of the first fully-controlled switching device and the emitter of the fourth fully-controlled switching device are respectively connected to the positive and negative output ends of the three-phase controlled rectifier circuit; the emitter of the third fully-controlled switching device is connected to the input end of the first diode, the output end of the first diode is connected to the input end of the second diode, and the output end of the second diode is connected to the collector of the second fully-controlled switching device; the emitter of the second fully-controlled switching device is connected to one end of the resonant inductor 9, the other end of the resonant inductor 9 is connected to one end of the resonant capacitor 10, and the other end of the resonant capacitor 10 is connected to one of the input interfaces of the step-up transformer 5.

[0041] To achieve LLC resonant soft switching in high-power power modules (hundreds of kilowatts to megawatts), this embodiment uses IGBTs (such as Infineon's IGBT modules), i.e., fully controlled switching devices 11. SiC devices can reduce switching losses and increase switching frequency (20kHz-100kHz), but attention must be paid to dv / dt suppression in the drive circuit. The transformer 2 described above uses a planar magnetic core (such as nanocrystalline or ferrite N87 material) or a multi-core parallel structure to reduce core losses. The winding layout is optimized to reduce leakage inductance (leakage inductance must be controlled within 5%-10% of the excitation inductance to avoid affecting the resonant parameters). The resonant inductor 9 uses an air-core inductor or a gapped magnetic core. The air gap must be evenly distributed to avoid saturation, and segmented winding can be used to reduce AC resistance.

[0042] Further, the relationship of the resonant inductance 9Lr, the resonant capacitance 10Cr, and the magnetizing inductance Lm needs to satisfy: resonant frequency , usually designed as the center value of the switching frequency; The magnetizing inductance Lm is large enough to ensure that ZVS can still be maintained at light load (Lm is too small to cause insufficient primary current to charge the junction capacitor).

[0043] Further, a digital control (such as DSP or FPGA) is introduced to monitor the load current and voltage in real time, and dynamically adjust the resonant frequency or auxiliary parameters through software algorithm, for example, when the load is reduced, the switching frequency is automatically increased to avoid ZVS failure caused by too small primary current; Light load (less than 50% rated power): high frequency variable frequency control is adopted to reduce the loss of magnetizing current; Medium and heavy load (50%-100%), combined with phase shift control (adjusting the phase difference of the upper and lower bridge arms on the primary side), while maintaining ZVS, expand the voltage regulation range to avoid too low frequency.

[0044] Optionally, the input ends of the first two diodes in the above three resonant branches are connected to each other, and after connection, the input ends are connected between the upper end capacitor 7 and the lower end capacitor 8 of the output end of the three-phase rectifier circuit 3.

[0045] In this embodiment, in order to improve the efficiency of the ion cyclotron three-level high-voltage power supply system and reduce the switching stress, the LLC resonant soft switching technology is used in the several hundred kilowatt high-power power supply module, so that the ion cyclotron high-voltage power supply can realize zero voltage switching (ZVS) or zero current switching (ZCS) through the resonant phenomenon compared with the three-level power supply module without soft switching technology, greatly reducing the switching loss of the switching device and improving the overall efficiency of the power supply. The voltage change rate and current change rate of the switching device are low, which helps to reduce electromagnetic interference (EMI), can work normally in a wide input voltage range, can better adapt to different power supply conditions and voltage fluctuations, and improves the applicability and stability of the power supply. Soft switching technology makes the voltage and current change relatively smooth when the switching device is turned on and off, reduces the stress on the switching device, prolongs the service life of the switching device, and improves the reliability of the system.

[0046] Embodiment 2: In order to realize the soft switching technology of three-level, realize the high efficiency of three-level high-voltage power supply, low electromagnetic interference, wide input voltage range and reduce the switching stress, etc., a high-power three-level power supply module with LLC resonant soft switching is proposed, which mainly consists of an AC switch 1, a transformer 2, a three-phase controllable rectifier circuit, a three-level inverter 4, an LLC resonant circuit, a step-up transformer 5, and a non-controlled rectifier circuit 6, as shown in Figure 1 , wherein: The AC switch 1 is used as the input control component of the power module, mainly for turning on or off the AC power supply. In the case of device startup, stop or failure, etc., the state of the AC switch 1 can be controlled to effectively manage and control the input AC power of the entire power module.

[0047] The transformer 2 performs voltage conversion, reducing the input AC voltage to an appropriate value according to the turns ratio. It converts the grid voltage to a voltage suitable for the subsequent three-phase controllable rectifier circuit. And it electrically isolates the input power supply from the subsequent circuit, which can prevent electrical interference.

[0048] The three-phase controllable rectifier circuit converts the input three-phase AC power to DC power. It adjusts the size of the rectified DC voltage according to the control signal through controllable rectifier devices (such as thyristors, etc.), achieving flexible adjustment of the output DC voltage. In order to increase the output voltage adjustment range of the three-level power module.

[0049] The three-phase controllable rectifier circuit rectifies and filters the input AC power, reducing the AC component, making the output DC voltage smoother and more stable. In high-power applications, a stable DC bus voltage is crucial for the normal operation of subsequent circuits, as it can provide high-quality DC power for subsequent devices such as inverters.

[0050] The three-level inverter 4 can effectively reduce the voltage stress of the switching device. In high-power applications, high voltage and large current are common, and through the three-level topology, the voltage stress of each switching device is reduced, which is conducive to the selection of lower voltage grade switching devices, reducing costs, and improving system reliability.

[0051] The LLC resonant circuit realizes soft switching function. In high-power power modules, switching loss is an important issue. The LLC resonant circuit greatly reduces switching loss by making the switching device turn on and off at zero voltage or zero current, improving the efficiency of the power module.

[0052] The LLC resonant circuit shapes and filters the output voltage and current, further improving the quality of the output AC power, making the output waveform closer to the ideal sine wave, and also helping to match the impedance characteristics of the load, improving energy transmission efficiency.

[0053] The step-up transformer 5 boosts the AC voltage. The AC voltage obtained after the previous circuit processing does not meet the requirements of the load, and the step-up transformer 5 can increase the AC voltage to the required value according to the turns ratio to meet the demand of the load for high voltage. It can play a role in isolation and impedance matching. It can isolate the electrical connection between the front and rear stages, and through appropriate turns ratio design, it can adjust the impedance relationship between the front and rear stages, so that the power module and the load can better realize energy transmission.

[0054] The uncontrolled rectification circuit 6 converts the boosted AC voltage into DC voltage. The uncontrolled rectification circuit 6 is generally composed of diodes 12 and other uncontrolled rectification devices, which convert the AC voltage into DC voltage to provide DC power for the final load.

[0055] Further, in actual use, the input end of the AC switch 1 is connected with the power grid or the superior power distribution room, and the output end of the AC switch 1 is connected with the primary side of the transformer 2; the secondary side of the transformer 2 is connected with the AC input side of the three-phase rectification circuit 3, and the output DC side of the three-phase rectification circuit 3 is connected with the DC input side of the three-level inverter 4; the AC output side of the three-level inverter 4 is connected with the primary side of the boost transformer 5, and the secondary side of the boost transformer 5 is connected with the AC input side of the uncontrolled rectification circuit 6; the output DC voltage of the uncontrolled rectification circuit 6 is the output voltage of the three-level power module.

[0056] Please refer to Figure 2 , Figure 2 The schematic diagram of the three-phase neutral point clamped inverter with LLC resonant soft switching provided by the application; the upper end capacitor 7 and the lower end capacitor 8 are connected in series and are connected in parallel with the three-phase rectification circuit 3, which plays a role of rectification filtering; the neutral point clamped inverter is composed of fully controlled switching devices 11 and diodes 12 in the three-level inverter 4, and in the three-phase output, the resonant inductor 9 and the resonant capacitor 10 of each phase are connected in series, and then are connected with the excitation inductor composed of the equivalent inductor of the primary winding of the boost transformer 5 to form an LLC resonant circuit.

[0057] Optionally, the AC switch 1 of the three-level power module determines whether the external AC power can enter the power module. In the system starting stage, the AC switch 1 is closed to allow the AC power to enter the subsequent circuit for processing; and when it is necessary to stop power supply or an emergency occurs, the AC switch 1 is quickly closed to cut off the AC power input, so as to ensure the safe operation of the entire module; the AC switch 1 of the three-level power module can quickly respond to abnormal electrical conditions such as overload and short circuit; when the current in the circuit suddenly and sharply increases and exceeds the safety threshold, the AC switch 1 will immediately act to prevent excessive current from entering and avoid damaging the subsequent electronic components due to overcurrent.

[0058] In a possible embodiment, since the amplitude of the AC voltage provided by the power grid may not meet the requirements of the subsequent circuit of the power module, the transformer 2 reduces the input AC voltage to an appropriate size through the windings with different turns ratios, so as to ensure that the subsequent electronic devices can work normally under the appropriate voltage.

[0059] In a possible embodiment, the three-phase controllable rectifier circuit is a key part of converting three-phase alternating current into direct current. It uses controllable rectifier devices to flexibly control the size of the direct current output voltage according to actual needs, and can preliminarily control the direct current input voltage of the inverter.

[0060] In a possible embodiment, in the process of converting alternating current into direct current, some voltage fluctuations and alternating components are inevitably generated. The three-phase controllable rectifier circuit effectively reduces these fluctuations and alternating components through filtering and other operations, making the output direct current smoother and more stable, and providing high-quality direct current power for the three-level inverter 4.

[0061] In a possible embodiment, through the output voltage regulation of the three-phase controllable rectifier circuit, in cooperation with the output regulation of the three-level inverter 4, the output voltage regulation range of the three-level power module can be widened.

[0062] In a possible embodiment, the three-level inverter 4 is a device that converts direct current back into alternating current. It is more advanced than traditional inverters, and can make the output alternating voltage waveform closer to an ideal sine wave by outputting more levels, greatly reducing the harmonic component in the output voltage and reducing the adverse effects on the load.

[0063] In a possible embodiment, the special topology of the three-level inverter 4 reduces the voltage stress on each switching device, reducing the requirements for the voltage withstand level of individual switching devices. This not only reduces costs, but also improves the reliability and stability of the entire system.

[0064] In a possible embodiment, after a series of circuit processing, the alternating voltage may not meet the requirements of some loads. The step-up transformer 5 will play its role, according to the turns ratio to raise the alternating voltage to an appropriate height, and push the voltage to a higher level to meet the demand of the load for high voltage.

[0065] In a possible embodiment, the step-up transformer 5 electrically isolates the front and rear stages of the circuit, avoiding electrical interference between the front and rear stages.

[0066] In a possible embodiment, the uncontrolled rectifier circuit 6 is a device that converts alternating current into direct current. It is mainly composed of diodes 12 and other uncontrollable rectifier devices, and converts the alternating voltage after the step-up into direct current voltage to provide direct current power for the final load.

[0067] In a possible embodiment, the upper end capacitor 7 and the lower end capacitor 8 provide a more stable direct current power source for the three-level inverter 4.

[0068] In one possible embodiment, the equivalent inductance of the primary winding of the step-up transformer 5 is one of the inductances constituting the LLC resonance, together with another resonant inductance 9 and a resonant capacitance 10 in the LLC resonant circuit. In the resonant state, the current and voltage in the circuit exhibit a special periodic variation law, so that the switching tube can be turned on and off under the condition of zero voltage or zero current, thereby reducing switching loss.

[0069] In one possible embodiment, in the LLC resonant circuit, the resonant inductance 9 is one of the core elements for achieving resonance. When the circuit is working, it periodically exchanges energy with the capacitor, so that the current and voltage in the circuit change according to the sine law. This resonance phenomenon is the basis for the LLC circuit to achieve soft switching.

[0070] In one possible embodiment, the resonant inductance 9 can limit the rate of change of current, so that the current waveform is smoother and sudden changes are avoided. Together with other elements, it effectively transmits the input electrical energy to the load end. In different working stages, such as the on and off stages of the switching tube, the energy state in the resonant inductance 9 changes, and it works with elements such as the transformer 2 and the capacitor to ensure stable transmission of energy.

[0071] In one possible embodiment, the resonant capacitance 10 is an indispensable part of the LLC resonant circuit, which determines the resonant frequency of the circuit together with the resonant inductance 9. The size of its capacitance value directly affects the resonant frequency. By reasonably selecting the capacitance value, the circuit can be made to work near the desired resonant frequency, thereby realizing functions such as soft switching.

[0072] In one possible embodiment, the resonant capacitance 10 plays a role in storing electrical energy. It absorbs and stores electrical energy at some moments in a period, and releases the stored electrical energy at other moments. The resonant capacitance 10 also has a filtering function, which can filter out high-frequency noise in the circuit, making the output voltage smoother.

[0073] In one possible embodiment, the step-up transformer 5 is a key component connecting the input and the output, and plays an important role in energy conversion and transmission. It couples the electrical energy on the primary side to the secondary side through electromagnetic induction principle. In the resonance process, the energy on the primary side is coupled to the secondary side through the magnetic field of the transformer 2, realizing voltage transformation and energy transfer, thereby providing appropriate voltage and power for the load.

[0074] The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-power three-level power supply module with LLC resonant soft switching, characterized in that: The system comprises an AC switch, a transformer, a three-phase controlled rectifier circuit, a three-level inverter, a step-up transformer and an uncontrolled rectifier circuit connected in sequence, wherein: An LLC resonant circuit is provided in the three-level inverter, and the input end of the LLC resonant circuit is connected to the step-up transformer; the LLC resonant circuit includes three interconnected resonant branches and is used to shape and filter the output voltage and output current, and to turn on and / or off the switching devices in the power module under zero voltage or zero current conditions.

2. A high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The AC switch is an input control component of the power module. The input end of the AC switch is connected to the external AC power supply, and the output end of the AC switch is connected to the transformer and is used to connect or disconnect the external AC power supply.

3. The high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The output end of the transformer is connected to the input end of the three-phase controlled rectifier circuit and is used to increase or decrease the input alternating current to a voltage value that can be processed by the three-phase controlled rectifier circuit.

4. The high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The three-phase controlled rectifier circuit is used to rectify and filter the three-phase alternating current output by the transformer and convert it into direct current. The voltage of the output direct current is also regulated by the controllable rectifier device in the circuit.

5. The high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The input end of the three-level inverter is connected to the output end of the three-phase controlled rectifier circuit, which is used to reduce the voltage stress of the switching device in the power module and to convert the direct current output by the three-phase controlled rectifier circuit into alternating current.

6. The high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The input end of the boost transformer is connected to the output end of the three-level inverter, and is used to boost the alternating current output by the three-level inverter to a required voltage value.

7. The high-power three-level power supply module with LLC resonant soft switching according to claim 1, characterized in that: The input end of the uncontrolled rectifier circuit is connected to the output end of the step-up transformer and is used to convert the AC power of the required voltage value output by the step-up transformer into DC power, and the DC power is the output of the power module.

8. A high-power three-level power supply module with LLC resonant soft switching according to any one of claims 1 to 7, characterized in that: The resonant branch includes a first diode, a second diode, a first fully-controlled switching device, a second fully-controlled switching device, a third fully-controlled switching device, a fourth fully-controlled switching device, a resonant inductor, and a resonant capacitor, wherein: The emitter of the first fully-controlled switching device is connected to the collector of the second fully-controlled switching device, the emitter of the second fully-controlled switching device is connected to the collector of the third fully-controlled switching device, the emitter of the third fully-controlled switching device is connected to the collector of the fourth fully-controlled switching device, and the collector of the first fully-controlled switching device and the emitter of the fourth fully-controlled switching device are respectively connected to the positive and negative output terminals of the three-phase controlled rectifier circuit; The emitter of the third fully-controlled switching device is connected to the input end of the first diode, the output end of the first diode is connected to the input end of the second diode, and the output end of the second diode is connected to the collector of the second fully-controlled switching device; The emitter of the second fully-controlled switching device is connected to one end of the resonant inductor, the other end of the resonant inductor is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one input interface of the step-up transformer.

9. The high-power three-level power supply module with LLC resonant soft switching according to claim 8, characterized in that: The input ends of the first diodes in the three resonant branches are all connected to each other, and after being connected, are also connected between the upper capacitor and the lower capacitor of the output end of the three-phase rectifier circuit.

10. Application of a high-power three-level power supply module with LLC resonant soft switching according to any one of claims 1 to 9 in a DC power supply scenario.

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