Power supply protection circuit capable of inhibiting neutral beam ignition impact and neutral beam injection system

Abstract

The invention relates to the technical field of electronic power, and discloses a power supply protection circuit capable of inhibiting neutral beam ignition impact, and a neutral beam injection system, an output protection circuit comprises a filtering sub-circuit, an IGBT loop, a secondary clamping protection sub-circuit, a buffer sub-circuit and an output stage clamping protection sub-circuit which are arranged in sequence, the filtering sub-circuit is used for receiving the pulsating direct-current voltage and outputting the stable direct-current voltage which is purer, has smaller ripples and can discharge safely when a power supply is turned off; the IGBT loop is used for receiving stable direct-current voltage and carrying out over-current and over-voltage protection on an IGBT element in the IGBT loop when the IGBT element is rapidly turned off; the output-stage clamping protection sub-circuit is used for carrying out primary clamping on the impulse voltage; the secondary clamping protection sub-circuit is used for carrying out secondary clamping on the impulse voltage when the impulse voltage is not eliminated after the output-stage clamping protection sub-circuit carries out primary clamping; and the buffer circuit is used for attenuating the impulse voltage from the output-stage clamping protection sub-circuit. According to the invention, the damage risk of the IGBT can be reduced.

Description

Technical Field

[0001] This invention relates to the field of electronic power technology, specifically to a power supply protection circuit and a neutral beam injection system for suppressing neutral beam arcing impact. Background Technology

[0002] Neutral beam injection heating and current-driven heating are indispensable heating systems for magnetic confinement fusion experimental devices due to their clear physical mechanisms, high heating efficiency, and wide applicable plasma parameter range. Neutral beam injection heating is a technique that heats plasma by injecting high-energy neutral particles into a magnetic confinement fusion device. Because of its significant heating effect, it has been widely used in magnetic confinement fusion devices. The principle is that after fast neutral atoms are injected into the fusion plasma, they become charged through collisional ionization and charge exchange, and are then captured by the magnetic field. The captured fast ions collide with plasma ions and electrons, transferring energy to the ions and electrons, thus increasing the plasma temperature. In addition, neutral beam injection can also be used to achieve sensorless current-driven heating, improve plasma confinement, fuel feeding, and plasma parameter diagnostics.

[0003] The neutral beam ion source consists of a discharge chamber and an accelerator. Plasma is generated in the discharge chamber through gas discharge. The accelerator electrodes are connected to a high-voltage power supply and a suppressor power supply. By applying voltages of different potentials between the electrode plates, an electrostatic field is formed between them. The suppressor power supply is connected to the accelerator's third electrode, creating an electric field between the third and fourth electrodes to suppress the backflow of electrons near the neutralization pipe opening.

[0004] Before entering the neutralization chamber, the ion beam's state is influenced by the suppressor electric field. A suitable electric field can provide better initial conditions for the ion beam upon entering the neutralization region, thus improving neutralization efficiency. When the ion beam enters the neutralization chamber with a more regular shape and appropriate energy distribution, it can interact more effectively with the neutralizing gas, converting ions into high-energy neutral particles, thereby improving the overall performance of the neutral beam injection system.

[0005] During ion extraction, some stray ions are inevitably generated. If these stray ions are not controlled, they may damage other components of the neutral beam injection system or interfere with the normal injection process of the ion beam. The electric field generated by the suppressor power supply can effectively suppress these stray ions, confining them to a certain area or guiding them into a specific collection device.

[0006] Therefore, the suppressor power supply plays a crucial role in neutral beam injection systems. The anode of the suppressor power supply is connected to the negative terminal of the high-voltage power supply. When the load terminal accelerates high-voltage arcing discharge, a portion of the high-voltage charge is divided and transferred to the negative output terminal of the suppressor. Since the accelerating high voltage is positive, the negative output terminal of the suppressor bears a positive impulse voltage. In existing suppressor power supplies, in addition to generating large current pulses during arcing, it also causes severe voltage fluctuations. The operating voltage of the suppressor power supply is relatively stable, but the discharge channel generated by arcing alters the local electric field distribution, leading to voltage spikes on the suppressor. These voltage spikes may exceed the withstand voltage limits of the internal components of the power supply, potentially breaking down the insulation layers of components such as Insulated Gate Bipolar Transistors (IGBTs), thus damaging these components. Therefore, a protection circuit is needed to suppress the voltage on the output side of the suppressor power supply during neutral beam arcing and absorb the corresponding energy.

[0007] In view of this, in order to improve the protection of the suppressor power supply during arcing discharge in the neutral beam injection system and enhance the robustness of the suppressor power supply, a power supply protection circuit with neutral beam arcing impact suppression is proposed. Summary of the Invention

[0008] This invention provides a power supply protection circuit and a neutral beam injection system for suppressing neutral beam arcing impact, in order to solve the above-mentioned problems.

[0009] This invention is achieved through the following technical solution: A power supply protection circuit for suppressing neutral beam arcing impacts includes a power supply connected to an output protection circuit via a pre-processing circuit. The output protection circuit receives a pulsating DC voltage processed by the pre-processing circuit and filters and clamps this pulsating DC voltage to obtain a stable output voltage for supplying the load. Along the current transmission direction, the output protection circuit includes, in sequence, a filter sub-circuit, an IGBT circuit, a secondary clamping protection sub-circuit, a buffer sub-circuit, and an output stage clamping protection sub-circuit. The filter sub-circuit is used to receive the pulsating DC voltage and perform noise filtering, energy buffering and safe discharge processing on the pulsating DC voltage to output a purer, less rippled, and stable DC voltage that can safely discharge when the power is turned off. The IGBT circuit is used to receive the stable DC voltage and to provide overcurrent and overvoltage protection for the IGBT elements in the IGBT circuit during rapid turn-off. The output stage clamping protection sub-circuit is used to clamp the impulse voltage generated when high-voltage arcing discharge occurs at the load end, so that the voltage across the IGBT element is controlled within a safe range. The secondary clamping protection sub-circuit is used to perform a secondary clamping of the surge voltage when the output stage clamping protection sub-circuit fails to eliminate the surge voltage after the first clamping, so that the voltage across the IGBT element is controlled within a safe range. The buffer circuit is used to attenuate the surge voltage from the output stage clamp protection sub-circuit.

[0010] As an optimization, the filter sub-circuit includes a filter capacitor, a discharge resistor, and a discharge switch, wherein the filter capacitor is connected in parallel with a first series link that is connected in series with the discharge circuit and the discharge switch.

[0011] As an optimization, the IGBT circuit includes an IGBT element, an IGBT clamping arrester, an absorption resistor, and an absorption capacitor. The absorption resistor and absorption capacitor are connected in series to form an RC absorption protection sub-circuit. The RC absorption protection sub-circuit and the IGBT clamping arrester are connected in parallel. The two ends of the IGBT clamping arrester are located at the emitter and collector of the IGBT element. The collector of the IGBT element is connected to the filter sub-circuit, and the emitter of the IGBT element is connected to the secondary clamping protection sub-circuit.

[0012] As an optimization, the secondary clamping protection sub-circuit includes a protection surge arrester and a freewheeling diode connected in parallel. The protection surge arrester and the freewheeling diode are connected in parallel, and the anode of the freewheeling diode is connected to the IGBT circuit and the buffer circuit respectively, and the cathode of the freewheeling diode is connected to the filter sub-circuit and the buffer circuit respectively.

[0013] As an optimization, two buffer sub-circuits are provided, and the two buffer circuits are respectively connected to the anode and cathode of the freewheeling diode. The buffer sub-circuit includes a current-limiting resistor, a freewheeling resistor, and a short-circuit inductor. The current-limiting resistor is connected in series with a parallel link formed by the freewheeling resistor and the short-circuit inductor. The end of the current-limiting resistor away from the parallel link is connected to the secondary clamping protection sub-circuit, and the end of the parallel link away from the current-limiting resistor is connected to the output stage clamping protection sub-circuit.

[0014] As an optimization, the output stage clamping protection sub-circuit includes an output absorption capacitor, an output discharge resistor, and an output clamping surge arrester connected in parallel, and the output terminal of the output stage clamping protection sub-circuit is connected to the suppression electrode.

[0015] As an optimization, along the current transmission direction, the preprocessing circuit includes an EMI circuit, a three-phase rectifier circuit, a full-bridge inverter circuit, a step-up transformer, and an uncontrolled rectifier circuit.

[0016] As an optimization, the power supply is a three-phase AC voltage.

[0017] As an optimization, a current sensor is provided between the IGBT circuit and the secondary clamping protection sub-circuit.

[0018] The present invention also discloses a neutral beam injection system, wherein the suppression electrode power supply of the neutral beam injection system is composed of the aforementioned power protection circuit that suppresses neutral beam arcing impact.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: Since neutral beam arcing generates instantaneous high-energy shocks, these shocks can cause serious damage to the electronic components inside the suppressor power supply. The power supply protection circuit of the present invention, which suppresses neutral beam arcing shocks, can effectively reduce the impact of such shocks on the power supply.

[0020] For neutral beam equipment, power supply stability is crucial. If the surge caused by the high-voltage charge drop onto the negative output terminal of the suppression electrode during arcing is not effectively suppressed, it will affect the generation and transmission of the neutral beam. The power protection circuit of this invention, which suppresses the arcing surge of the neutral beam, can ensure the stability of the power output and provide a stable power supply for the neutral beam equipment.

[0021] The clamping surge arrester in the suppressor power supply of the present invention can clamp the voltage across the IGBT within a safe range. By connecting the clamping surge arrester in parallel, the risk of IGBT damage can be greatly reduced.

[0022] Since arcing impacts can also cause sudden changes in current, the short-circuit inductor in the power protection circuit of this invention enables the power protection circuit to have an overcurrent protection mechanism, which can quickly respond to such current surges. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the module connection of a power supply protection circuit for suppressing neutral beam arcing impact according to the present invention. Figure 2 This is a schematic diagram of the module connection for the output protection circuit. Figure 3 This is a circuit connection diagram for the output protection circuit.

[0024] The attached diagram shows the markings and corresponding component names: 1-Three-phase AC input; 2-EMI circuit; 3-Three-phase rectifier circuit; 4-Full-bridge inverter circuit; 5-Step-up transformer; 6-Uncontrolled rectifier circuit; 7-Output protection circuit; 8-Filter capacitor; 9-Bleeding resistor; 10-Bleeding switch; 11-Absorption resistor; 12-Absorption capacitor; 13-IGBT clamping arrester; 14-IGBT element; 15-Current sensor; 16-Freewheeling diode; 17-Protective arrester; 18-Current limiting resistor; 19-Freewheeling resistor; 20-Short-circuit protection inductor; 21-Output absorption capacitor; 22-Output discharge resistor; 23-Output clamping arrester. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0026] To protect the suppressor power supply of the neutral beam injection system, and to ensure that the suppressor power supply can effectively protect the key components when the neutral beam injection system sparks, thereby achieving the stability and reliability of the suppressor power supply operation and avoiding frequent maintenance, this invention proposes a power supply protection circuit that suppresses neutral beam sparking impact.

[0027] This embodiment 1 provides a power supply protection circuit that suppresses neutral beam arcing impact, such as... Figures 1-3 As shown, the power supply is connected to the output protection circuit through the preprocessing circuit. The output protection circuit receives the pulsating DC voltage obtained after processing by the preprocessing circuit and filters and clamps the pulsating DC voltage to obtain a stable output voltage to supply the load.

[0028] In some embodiments, a pre-processing circuit is further provided between the output protection circuit and the power supply. Along the current transmission direction, the pre-processing circuit includes an EMI circuit, a three-phase rectifier circuit, a full-bridge inverter circuit, a step-up transformer, and an uncontrolled rectifier circuit. In some embodiments, the power supply is a three-phase AC voltage.

[0029] In other words, the entire suppressor power supply mainly consists of an EMI circuit, a three-phase rectifier circuit, a full-bridge inverter circuit, a step-up transformer, an uncontrolled rectifier circuit, and an output protection circuit.

[0030] like Figure 1As shown, the main circuit of the suppressor power supply consists of a three-phase AC input 1, an EMI circuit 2, a three-phase rectifier circuit 3, a full-bridge inverter circuit 4, a step-up transformer 5, an uncontrolled rectifier circuit 6, and an output protection circuit 7. The three-phase AC input 1 is powered by the upstream power distribution room, and its input terminal is connected to the upstream power distribution room. The output terminal of the three-phase AC input 1 is connected to the input terminal of the EMI circuit 2, and the output terminal of the EMI circuit 2 is connected to the input terminal of the three-phase rectifier circuit 3. The three-phase rectifier circuit 3 is connected to the DC input terminal of the full-bridge inverter circuit 4, and its AC output terminal is connected to the primary input of the step-up transformer 5. The secondary output of the step-up transformer 5 is connected to the AC input terminal of the uncontrolled rectifier circuit 6, and its DC output terminal is connected to the input terminal of the output protection circuit 7. The output of the output protection circuit 7 provides the DC voltage required by the suppressor.

[0031] In this technical solution, the suppressor power supply uses a three-phase AC input. An EMI circuit suppresses electromagnetic interference signals from the three-phase AC power supply, resulting in a cleaner input power signal for the three-phase rectifier circuit. The three-phase rectifier circuit rectifies the input AC voltage to a DC signal compatible with the full-bridge inverter circuit. The full-bridge inverter circuit controls its fully controlled components to output the required voltage level. This voltage is then boosted by a step-up transformer and rectified by an uncontrolled rectifier circuit to obtain the suppressor DC voltage required for the neutral beam. During power supply arcing, the power protection circuit uses a passive operation to clamp and protect the voltage, preventing overvoltage damage to the controllable components (IGBTs) or rectifier bridge in the suppressor power supply, thus avoiding increased maintenance workload and reduced equipment robustness.

[0032] The three-phase AC input is used to connect the upstream distribution room and the downstream suppressor power supply. It provides stable and balanced power to the suppressor power supply, and the three-phase AC input can provide sufficient energy to drive the suppressor load.

[0033] Next, we will introduce in detail the working principle and function of each circuit of the suppressor power supply in this embodiment.

[0034] External interference signals may enter the power supply through power lines or spatial radiation. EMI circuits act as a barrier, preventing these external interference signals from entering and thus improving the power supply's anti-interference performance. In other words, EMI circuits are primarily used to suppress electromagnetic interference signals in the power supply (i.e., three-phase AC power). They typically consist of a filter network composed of inductors, capacitors, and other components. Common-mode inductors can suppress common-mode interference signals. When an interference signal passes through a common-mode inductor, its energy is attenuated because the inductor impedes the changing current. Simultaneously, capacitors can bypass high-frequency interference signals, guiding them to ground, thus making the power supply signal entering subsequent circuits cleaner and providing a stable input environment for subsequent circuits such as three-phase rectifiers.

[0035] It should be noted that EMI circuits are existing circuits that are very mature and widely used in power supplies and electronic devices. Their design and performance are subject to clear international and industry standards, such as the IEC 61000 series (e.g., IEC 61000-4-2 / 4 immunity test) and FCC (Federal Communications Commission) Part 15, which specify the limits for electromagnetic emission and immunity of equipment. Therefore, they will not be elaborated on here.

[0036] Three-phase rectifier circuits are primarily used to convert three-phase AC power into DC power. In neutral beam suppressor power systems, subsequent circuits such as full-bridge inverters typically require DC power as input. The three-phase rectifier circuit utilizes the unidirectional conductivity of its components to rectify the positive and negative half-cycles of the three-phase AC power, ensuring that the output current direction remains consistent, thus producing a pulsating DC voltage at the output. The DC voltage output by this three-phase rectifier circuit can be adjusted according to specific application requirements.

[0037] A full-bridge inverter circuit converts DC power to AC power. In a neutral beam suppressor power supply, a full-bridge inverter circuit can obtain AC power with a specific frequency and amplitude. It allows for flexible adjustment of the frequency and amplitude of the output AC voltage. By controlling the conduction time and sequence of the four switching transistors (such as IGBTs) in the full-bridge inverter circuit, the frequency and amplitude of the output AC voltage can be changed, thus generating AC current in the primary winding of the transformer. This enables the suppressor power supply to provide precise power according to the specific operating requirements of the suppressor, thereby achieving regulation of the suppressor power supply's output voltage.

[0038] The full-bridge inverter circuit can use PWM control to phase-shift full-bridge series resonance. Under the control of the PWM controller, the switching devices in the full-bridge inverter are turned on and off in a certain sequence, so that the switching tubes operate in soft-switching mode, which greatly reduces switching losses and ensures high reliability and high conversion efficiency at high frequencies.

[0039] A step-up transformer boosts the AC voltage output from a full-bridge inverter circuit. In a neutral-beam suppressor power supply system, a higher voltage is required to meet the operating requirements of the suppressor. The step-up transformer utilizes the principle of electromagnetic induction, increasing the voltage based on the turns ratio of the primary and secondary windings, thus raising the input AC voltage to the required level. While boosting the voltage, the step-up transformer also provides electrical isolation.

[0040] The output protection circuit is designed to protect the suppressor power supply from damage to components during use by preventing the increase in the suppressor output voltage caused by arcing during neutral beam injection. This is achieved through multi-stage protection measures. In other words, the output protection circuit provides overvoltage and overcurrent protection for the suppressor power supply. Most importantly, during accelerated high-voltage arcing discharge at the load end, the negative output terminal of the suppressor stage experiences a positive impulse voltage because the accelerating high voltage is positive. In this case, the output protection circuit provides protection against sinusoidal impulse voltage.

[0041] An uncontrolled rectifier circuit converts the AC voltage output from the step-up transformer back into DC voltage. This is because the suppressor power supply may eventually require a DC power source to operate. The uncontrolled rectifier circuit utilizes the unidirectional conductivity of diodes to guide current through the load during the positive and negative half-cycles of the AC voltage, ensuring that the voltage across the load is always positive, thus rectifying the AC voltage into DC voltage.

[0042] An uncontrolled rectifier circuit is a basic power conversion circuit, mainly composed of diodes. It uses the unidirectional conductivity of diodes to convert alternating current (AC) into direct current (DC). Because the conduction and cutoff states of the diodes are entirely determined by the polarity of the AC input voltage and cannot be manually controlled, it is called an uncontrolled rectifier circuit.

[0043] Common uncontrolled rectifier circuits include single-phase half-wave rectifier circuits, single-phase bridge rectifier circuits, three-phase half-wave rectifier circuits, and three-phase bridge rectifier circuits. They are widely used in simple power supplies and low-power applications, such as single-phase bridge uncontrolled rectifier circuits commonly found in low-power electronic devices like mobile phone chargers. In applications where output voltage and current accuracy requirements are not high, uncontrolled rectifier circuits are widely used due to their simple structure and low cost.

[0044] In summary, the three-phase rectifier circuit, full-bridge inverter circuit, step-up transformer, and uncontrolled rectifier circuit are all conventional existing circuits, and will not be elaborated on here.

[0045] The reason for using a full-bridge inverter circuit to convert DC to AC and then outputting it to the step-up transformer, instead of directly outputting the three-phase input to the step-up transformer through the EMI circuit, is as follows: I. To meet the operational requirements of subsequent circuits: 1. Adapting to Power Conversion and Control Requirements: The full-bridge inverter circuit in the neutral beam injection system requires a stable DC input to precisely control the frequency, amplitude, and other parameters of the output AC voltage. The three-phase rectifier circuit first converts the three-phase AC to DC, providing a suitable DC bus voltage for the full-bridge inverter. This allows the inverter circuit to flexibly adjust to meet the specific voltage requirements of the suppressor power supply, such as precisely outputting the DC voltage required by the suppressor, which cannot be achieved by directly feeding AC into the transformer.

[0046] 2. Achieving Voltage Transformation and Electrical Isolation: Step-up transformers require suitable AC input to boost the voltage. The AC output from the full-bridge inverter circuit can be stepped up to the high voltage required for the suppressor to operate via a step-up transformer, while simultaneously achieving electrical isolation to ensure system safety. Directly inputting AC into the transformer makes it difficult to flexibly adjust the voltage and adapt to the complex requirements of the suppressor power supply regarding voltage amplitude, frequency, and electrical isolation.

[0047] II. Power Quality and Electromagnetic Compatibility Considerations: 1. Power Supply Purity Requirements: EMI circuits primarily suppress electromagnetic interference, but three-phase AC power directly enters the transformer, and its voltage and frequency are inherent characteristics of the power grid, resulting in fluctuations and harmonics. Through a rectification-inverter stage, the electrical energy undergoes secondary processing, making the AC power input to the transformer purer and more stable, reducing the impact of power grid interference, ensuring stable power output from the suppressor electrode, and preventing interference from being injected into other components of the system.

[0048] 2. Power Factor and Harmonic Mitigation: The three-phase rectifier circuit combined with the subsequent inverter circuit helps improve the power factor, reduce harmonic pollution on the grid side, and meet the power system's power quality requirements. Direct AC input to the transformer makes it difficult to effectively mitigate harmonics and optimize the power factor, and can easily affect the normal operation of the power grid and other equipment within the system.

[0049] III. Implementation of System Functions and Control: 1. Flexible voltage regulation and precise control: Through power electronic conversion of rectification-inversion, the frequency and amplitude of the output AC voltage can be precisely adjusted according to the actual needs of the suppressor power supply, adapting to the voltage requirements of the suppressor under different operating conditions, and realizing fine control of the neutral beam injection process, such as voltage clamping protection during arcing discharge. Direct AC power supply cannot achieve such flexible control.

[0050] 2. Protection and Reliability Requirements: The rectifier-inverter architecture facilitates the integration of various protection circuits, such as overcurrent, overvoltage, and IGBT turn-off overvoltage protection. Under abnormal operating conditions such as neutral beam arcing, the protection circuits can work together to suppress voltage spikes, absorb energy, protect critical components (such as IGBTs), and improve system reliability. Direct AC connection to a transformer lacks such protection mechanisms, and components are easily damaged by sudden voltage and current changes.

[0051] In summary, this rectifier-inverter-transformer architecture is designed by considering multiple factors such as system functional requirements, power quality control, equipment protection and reliability, in order to ensure the stable, efficient and reliable operation of the suppressor power supply in the neutral beam injection system.

[0052] In this embodiment, along the current transmission direction, the output protection circuit includes a filter sub-circuit, an IGBT circuit, a secondary clamping protection sub-circuit, a buffer sub-circuit, and an output stage clamping protection sub-circuit arranged sequentially.

[0053] Next, we will introduce the functions of each sub-circuit in the output protection circuit.

[0054] The filter sub-circuit is used to receive the pulsating DC voltage and perform noise filtering, energy buffering and safe discharge processing on the pulsating DC voltage to output a purer, less rippled, and stable DC voltage that can safely discharge when the power is turned off. The IGBT circuit is used to receive the stable DC voltage and to provide overcurrent and overvoltage protection for the IGBT elements in the IGBT circuit during rapid turn-off. The output stage clamping protection sub-circuit is used to clamp the impulse voltage generated when high-voltage arcing discharge occurs at the load end, so that the voltage across the IGBT element is controlled within a safe range. The secondary clamping protection sub-circuit is used to perform a secondary clamping of the surge voltage when the output stage clamping protection sub-circuit fails to eliminate the surge voltage after the first clamping, so that the voltage across the IGBT element is controlled within a safe range. The buffer circuit is used to attenuate the surge voltage from the output stage clamp protection sub-circuit.

[0055] It should be noted that the IGBT element is used to control the power supply to turn on and off, thereby controlling the voltage output of the power supply, and is equivalent to a switching device.

[0056] In simple terms, the filter circuit consists of a filter capacitor 8, a bleeder resistor 9, and a switch 10. The IGBT circuit includes an RC absorption protection circuit, an overcurrent protection circuit, and a clamping surge arrester. The output stage clamping protection circuit consists of an output clamping surge arrester 23, an output absorption capacitor 21, and an output discharge resistor 22. The secondary clamping protection circuit consists of a protective surge arrester 17 and a freewheeling diode 16, and the buffer circuit consists of a current-limiting resistor 18, a short-circuit withstand inductor 20, and a freewheeling resistor 19.

[0057] Next, we will introduce the specific structure of each sub-circuit in the power protection circuit.

[0058] In some embodiments, the filter sub-circuit includes a filter capacitor, a discharge resistor, and a discharge switch, wherein the filter capacitor is connected in parallel with a first series link that is connected in series with the discharge circuit and the discharge switch.

[0059] The filter sub-circuit of the power protection circuit mainly consists of a filter capacitor 8, a bleed resistor 9, and a bleed switch 10. The filter capacitor 8 ensures a smoother DC voltage output from the uncontrolled rectifier circuit, reducing output DC voltage ripple and providing a stable voltage for the suppressor. The bleed resistor 9 provides a discharge path when the power is off or the filter capacitor needs to discharge. Without the bleed resistor, the filter capacitor might remain charged for an extended period after the power is disconnected, posing a safety hazard to maintenance personnel. The bleed resistor allows the charge in the capacitor to be safely released in a short time; it is connected in parallel with the filter capacitor. The bleed switch controls whether the bleed resistor is connected to the filter capacitor. When the suppressor power supply is working normally, the bleed switch is not connected to the filter capacitor. When arcing occurs in the neutral beam, a trigger command to shut down the IGBT element 14 is issued, simultaneously controlling the bleed switch to connect to the filter capacitor for rapid energy release. In other words, the filter capacitor is mainly used to smooth the output voltage of the uncontrolled rectifier circuit, the bleeder resistor is mainly used to safely release the charge stored in the filter capacitor after the power is turned off, and the bleeder switch is used to control the operation of the bleeder resistor. The bleeder switch is opened during normal operation and closed during non-operation periods, so that the bleeder resistor is connected to the filter capacitor.

[0060] In some embodiments, the IGBT circuit includes an IGBT element, an IGBT clamping arrester, an absorption resistor, and an absorption capacitor. The absorption resistor and the absorption capacitor are connected in series to form an RC absorption protection sub-circuit. The RC absorption protection sub-circuit and the IGBT clamping arrester are connected in parallel. The two ends of the IGBT clamping arrester are located at the emitter and collector of the IGBT element. The collector of the IGBT element is connected to the filter sub-circuit, and the emitter of the IGBT element is connected to the secondary clamping protection sub-circuit.

[0061] The IGBT circuit in a power supply protection circuit includes an RC snubber protection circuit, an overcurrent protection circuit, and a clamping surge arrester. The RC snubber protection circuit absorbs overvoltages generated when the IGBT is turned off. When the IGBT turns off rapidly, the inductor in the circuit generates an induced electromotive force (EMF), which can cause a high voltage spike across the IGBT, potentially damaging it. The capacitor in the RC snubber protection circuit absorbs this overvoltage energy, effectively suppressing this turn-off overvoltage. The snubber resistor limits the discharge current of the snubber capacitor, thus protecting the IGBT from excessive voltage surges. The overcurrent protection circuit primarily monitors the current in the IGBT circuit. When the current exceeds a set safety threshold, the overcurrent protection circuit takes measures to protect the IGBT. When a momentary high voltage occurs in the circuit, such as a power system surge voltage, the clamping surge arrester can clamp the voltage across the IGBT within a safe range, preventing the IGBT from being damaged by excessive voltage. The clamping surge arrester's function is to limit the voltage across the IGBT.

[0062] In some embodiments, the output stage clamping protection sub-circuit includes an output absorption capacitor, an output discharge resistor, and an output clamping surge arrester arranged in parallel, and the output terminal of the output stage clamping protection sub-circuit is connected to the suppression electrode.

[0063] The output stage clamping protection circuit in a power supply protection circuit consists of an output clamping surge arrester, an output absorption capacitor, and an output discharge resistor. The output clamping surge arrester primarily clamps the voltage at the power supply output terminal. It prevents excessively high voltage spikes in the output voltage. For example, during load changes (arresting) or other interference, the output voltage (i.e., the impulse voltage, mainly caused by other power sources on the load) may rise instantaneously. The output clamping surge arrester limits this excessive voltage to a safe range. The output absorption capacitor further absorbs the spike voltage in the output overvoltage, further reducing the output overvoltage caused by load changes. When the output absorption capacitor needs to discharge, the output discharge resistor provides a discharge path.

[0064] In some embodiments, the secondary clamping protection sub-circuit includes a protection surge arrester and a freewheeling diode connected in parallel. The protection surge arrester and the freewheeling diode are connected in parallel, and the anode of the freewheeling diode is connected to the IGBT circuit and the buffer circuit, respectively. The cathode of the freewheeling diode is connected to the filter sub-circuit and the buffer circuit, respectively.

[0065] The secondary clamping protection sub-circuit in the power supply protection circuit consists of a surge arrester and a freewheeling diode. As the second-stage voltage protection device, it further strengthens protection against voltage spikes. When the primary protection (such as the output stage clamping protection sub-circuit) fails to completely eliminate voltage spikes or when a surge voltage of higher amplitude occurs, the surge arrester can clamp the voltage back within a safe range, providing double protection and improving the power system's resistance to overvoltage. It also further clamps the output overvoltage, further reducing the overvoltage value entering the suppressor power supply. The current loop for the forward impulse voltage flows through the freewheeling diode, preventing impact on the output IGBT element 14 and the rectifier bridge circuits of the suppressor stage. When the load accelerates high-voltage arcing discharge, the surge arrester further clamps the impulse voltage; the clamping voltage at this time is approximately half that of the output clamping surge arrester.

[0066] When the load side accelerates high-voltage arcing discharge, the output clamping surge arrester clamps the positive impulse voltage to a certain voltage range (such as clamping the impulse voltage to about 13kV). At the same time, the output absorption capacitor absorbs the spike voltage, so that the voltage on the output absorption capacitor is less than the clamping voltage of the output clamping surge arrester.

[0067] The output discharge resistor releases the energy of the output absorption capacitor after the subsequent circuit has been turned off.

[0068] In some embodiments, two buffer sub-circuits are provided, and the two buffer circuits are respectively connected to the anode and cathode of the freewheeling diode. The buffer sub-circuit includes a current-limiting resistor, a freewheeling resistor, and a short-circuit inductor. The current-limiting resistor is connected in series with a parallel link composed of the freewheeling resistor and the short-circuit inductor. The end of the current-limiting resistor away from the parallel link is connected to the secondary clamping protection sub-circuit, and the end of the parallel link away from the current-limiting resistor is connected to the output stage clamping protection sub-circuit.

[0069] The buffer circuit in the power supply protection circuit consists of a current-limiting resistor, a short-circuit protection inductor, and a freewheeling resistor. When the load terminal accelerates high-voltage arcing discharge, the impulse voltage (output voltage) after passing through the output stage clamping protection sub-circuit is further attenuated by the current-limiting resistor and the short-circuit protection inductor, which can further reduce the impulse energy. The freewheeling resistor is connected in parallel with the short-circuit protection inductor, and when the inductor releases energy, the freewheeling resistor can consume some of the energy.

[0070] The impulse voltage here is the voltage between 0V and negative voltage, which is provided by other power sources in the load during the ignition process. The impulse voltage transformation will cause a reverse voltage change (increase) in the preceding circuit.

[0071] When the load side accelerates high-voltage arcing discharge, the impact voltage of the output stage clamping protection sub-circuit is further attenuated by the anti-short-circuit inductor and the current limiting resistor, and then enters the secondary clamping protection sub-circuit. The freewheeling resistor then releases the energy on the anti-short-circuit inductor.

[0072] In some embodiments, a current sensor is provided between the IGBT circuit and the secondary clamping protection sub-circuit.

[0073] The current sensor monitors changes in the power supply current of the suppression electrode. When the current in the circuit exceeds a preset safety threshold, the current sensor can detect this situation in a timely manner and issue an overcurrent signal. This signal can be transmitted to the protection circuit, triggering the protection circuit to take appropriate measures.

[0074] In summary, the output protection circuit 7 consists of a filter capacitor 8, a bleeder resistor 9, a bleeder switch 10, an absorption resistor 11, an absorption capacitor 12, an IGBT clamping surge arrester 13, an IGBT 14, a current sensor 15, a freewheeling diode 16, a protective surge arrester 17, a current-limiting resistor 18, a freewheeling resistor 19, a short-circuit withstand inductor 20, an output absorption capacitor 21, an output discharge resistor 22, and an output clamping surge arrester 23. The filter capacitor 8 is connected in parallel with the DC output terminal of the uncontrolled rectifier circuit 6. The bleeder resistor 9 is connected in series with the bleeder switch 10 and then in parallel with the filter capacitor 8. The absorption resistor 11 and the absorption capacitor 12 are connected in series to form an RC absorption protection circuit. This RC absorption protection circuit is connected in parallel with the IGBT clamping surge arrester 12 to form the protection circuit for the IGBT 14. The protection circuit for the IGBT 14 and the IGBT 14 are connected in parallel to form an IGBT loop. The negative terminal of the filter capacitor 8 is connected to the collector of the IGBT 14, and the emitter of the IGBT 14 is connected to the anode of the freewheeling diode 16. The current sensor 15 is connected to the line connecting the emitter of the IGBT 14 and the anode of the freewheeling diode 16 to measure the current and achieve overcurrent protection through current feedback. The cathode of the freewheeling diode 16 is connected to the positive terminal of the filter capacitor, and the surge arrester 17 is connected in parallel with the freewheeling diode 16. The short-circuit inductor 20 and the freewheeling resistor 19 are connected in parallel and then connected in series with the current-limiting resistor 18 to form a buffer circuit. The inputs of the buffer circuit are connected to the positive and negative terminals of the surge arrester 17, respectively. The output terminals of the two buffer circuits are connected to the positive and negative terminals of the output absorption capacitor 21, respectively. The output discharge resistor 22 is connected in parallel with the output absorption capacitor 21. The output clamping surge arrester 23 is connected in parallel with the output discharge resistor 22. The negative terminal of the output absorption capacitor 21 is connected to the negative terminal of the suppression electrode, resulting in a negative output voltage. The positive terminal of the output absorption capacitor 21 is connected to the positive terminal of the suppression electrode and then connected to ground, resulting in a zero output voltage.

[0075] To address the aforementioned structure, the "Power Supply Protection Circuit with Neutral Beam Arresting Impact Suppression" solution provided by this invention, based on existing power electronics technology, solves the technical pain points of neutral beam suppressor power supplies in high-voltage arcing scenarios, such as "insufficient overvoltage impact protection, easy device damage, and low reliability," through three core innovations: multi-level protection topology reconstruction, directional discharge of arcing impact, and passive collaborative protection mechanism.

[0076] I. Differentiated Reconstruction of Multi-Level Protection Topology: Breaking Through the Limitations of Traditional Single-Level Protection Traditional power supply protection circuits often employ a "single-stage clamping + simple buffering" structure, which is ill-suited to handle the high-frequency, high-voltage, and high-energy surges (such as forward surge voltages reaching 13kV) during neutral beam arcing. This solution innovatively designs a three-stage progressive protection topology: "output stage clamping → buffer attenuation → secondary clamping," forming a complete protection chain of "source suppression - energy attenuation - secondary fallback." Specific innovations are as follows: 1. The cooperative mechanism of hierarchical clamping: The output stage clamping protection sub-circuit (output clamping surge arrester + output absorption capacitor) serves as the first line of defense, initially clamping the arcing impulse voltage to a safe threshold (such as 13kV), while absorbing spikes and glitches through the output absorption capacitor to reduce voltage fluctuations. The secondary clamping protection sub-circuit (protection arrester + freewheeling diode) serves as the second line of defense. When the primary clamping fails to completely eliminate the impact, it further clamps the voltage to a lower value (approximately 50% of the primary clamping voltage), forming a "stepped voltage reduction" to prevent the single-stage clamping element from bearing excessive energy. This "two-stage clamping voltage differentiation design" (13kV for the first stage / 6.5kV for the second stage) is a customized solution for the characteristics of the neutral beam forward impulse voltage, which solves the contradiction of traditional single-stage clamping that "either the clamping is insufficient or the stress on the components is too great".

[0077] 2. Directional energy attenuation of the buffer circuit: The buffer sub-circuit (current-limiting resistor + short-circuit inductor + freewheeling resistor) is connected in series between the two clamping stages, instead of the traditional parallel structure: The current-limiting resistor limits the peak inrush current, and the short-circuit inductor uses its "impedance current surge" characteristic to slow down the energy release rate and avoid excessive instantaneous power. The freewheeling resistor is connected in parallel with the short-circuit inductor to specifically consume the residual energy released by the inductor, thus solving the problem of "incomplete energy absorption and easy secondary bounce" in traditional buffer circuits. This topology allows impact energy to be "dissipated in stages" along the transmission path, rather than being concentrated in a single component, significantly improving the impact resistance of the protection circuit.

[0078] II. Design of a directional discharge path for arcing impact: to prevent damage to core components. During neutral beam ignition, the negative output terminal of the suppression electrode will experience a positive impulse voltage. In traditional circuits, the impulse current may flow in reverse through core components such as the IGBT and rectifier bridge, leading to overvoltage breakdown. This solution innovatively designs a "directional discharge circuit for positive impulse current," achieving "harmless conduction" of impulse energy. 1. Directional conduction mechanism of a freewheeling diode: The freewheeling diode in the secondary clamping protection sub-circuit is designed as a "dedicated path for forward surge current": when a forward surge voltage is generated at the load end, the current preferentially flows through the freewheeling diode to form a loop, rather than flowing through the emitter-collector electrode of the IGBT or the diode in the uncontrolled rectifier circuit. This design utilizes the unidirectional conductivity of the diode to "drain" the surge current to a safe path, preventing the core power devices (IGBT, rectifier bridge) from being subjected to reverse voltage or overcurrent surges.

[0079] 2. Potential isolation and current path optimization: The positive terminal of the output stage clamping protection sub-circuit is grounded, and the negative terminal is connected to the negative terminal of the suppression electrode, forming an impulse discharge path with "ground potential reference": the positive impulse voltage generated by arcing is referenced to ground and forms a closed loop through the output clamping arrester → buffer circuit → freewheeling diode → positive terminal of filter capacitor. The entire process does not pass through the inverter circuit or the front-end rectifier circuit, which physically isolates the impulse energy from the core control circuit, solving the fatal defect of "impulse current being reversed to the front stage" in traditional protection circuits.

[0080] III. Collaborative Working Mechanism of Passive Protection: High-Reliability Design Without Active Control Neutral beam arcing impacts are characterized by their suddenness, high frequency, and concentrated energy, potentially causing active protection circuits relying on MCU / DSP to fail due to response delays. This solution innovatively employs a collaborative protection mechanism using entirely passive components, achieving adaptive protection with "zero control delay" through topology design. 1. Precise matching of component characteristics: The selection of output clamping surge arresters and protective surge arresters adopts "voltage gradient matching": the clamping voltage of the output clamping surge arrester is slightly higher than the rated voltage of the suppressor, and the clamping voltage of the protective surge arrester is slightly lower than the withstand voltage of the IGBT. This ensures that the impulse voltage first triggers the output stage clamping, and then triggers the secondary stage clamping, forming a "graded response" rather than "simultaneous action", thus avoiding the energy concentration impact on a certain component. The parameters of the current-limiting resistor and short-circuit inductor of the buffer circuit are optimized based on the impact energy calculation: the resistance value needs to limit the current to within 1.5 times the rated current of the IGBT, and the inductor value needs to make the current rise rate lower than the IGBT's tolerance threshold, so as to achieve "parametric protection" rather than "empirical design".

[0081] 2. Timing coordination of energy release: The energy processing timing of each component in the circuit is precisely designed: At the moment of ignition: the output absorption capacitor first absorbs the high-frequency spike (nanosecond-level response), and the output clamping arrester then conducts clamping (microsecond-level response). Mid-stage impact: The short-circuit inductor of the buffer circuit limits the rate of current change, and the current-limiting resistor consumes some energy; In the later stages of the impact: the freewheeling resistor consumes the energy stored in the inductor, and the output discharge resistor releases the residual charge of the output absorption capacitor (millisecond-level response); the passive response mechanism with full time-series coverage solves the problem that the response speed of the active protection circuit cannot keep up with the impact changes, and can still work stably under extreme conditions.

[0082] IV. System-level integration innovation: Adapting to the special requirements of neutral beam power supplies: For the specific application scenarios of neutral beam suppressor power supplies requiring "high voltage (10kV level), low ripple, and high reliability," the solution achieves several customized innovations in its overall architecture: 1. Deep collaboration with the inverter-rectifier link: The output protection circuit is not designed independently, but forms a closed loop with the preceding "full-bridge inverter + step-up transformer + uncontrolled rectifier" link: The pulsating DC output from the uncontrolled rectifier circuit is smoothed by the filter circuit and provides a stable DC bus for the IGBT circuit, avoiding the amplification effect of bus voltage fluctuations. The soft-switching control (PWM phase-shift resonance) of the full-bridge inverter circuit reduces its own switching noise, minimizes interference with the protection circuit, and ensures that the protection circuit only responds to real arcing impacts rather than internal system noise.

[0083] 2. A balanced design for safe release and rapid recovery: The "bleeder resistor + bleeder switch" combination in the filter circuit is not a traditional passive bleeder, but rather linked to the arcing protection: when arcing occurs, the bleeder switch immediately closes, quickly releasing the energy of the filter capacitor through the bleeder resistor, preventing the capacitor's stored energy from being released secondary through the impulse circuit. Simultaneously, it disconnects when the system recovers, without affecting normal operation. This design solves the problem of "slow system restart after protection" and improves the power supply's continuous operating capability.

[0084] In summary, the present invention has the following innovative points: Customized protection design for neutral beam arcing conditions: Neutral beam injection systems experience unique arcing discharge conditions, which can lead to high-voltage charge division and voltage spikes, threatening the safety of critical components in the suppressor power supply (such as IGBTs). Based on the rectifier-inverter-transformer architecture, this invention integrates specialized protection circuits (such as IGBT clamping arresters, output stage clamping protection, and buffer circuits). These protection circuits are designed to suppress and absorb the energy of neutral beam arcing impacts, representing an innovation tailored to a specific application scenario (neutral beam injection system suppressor power supply).

[0085] Precise control of the suppressor power supply function: The suppressor power supply needs to provide a stable and controllable DC voltage for the neutral beam injection system, and ensure the reliability of the power supply and system under abnormal operating conditions such as arcing. The design of the rectification-inverter stage, together with the protection circuit, can achieve precise control of the output voltage (such as voltage clamping and energy absorption), as well as protection for devices such as IGBTs. This application of power electronic topology around the special functions and operating conditions of the suppressor power supply in the neutral beam injection system is a customized innovation based on the conventional architecture, reflecting a creative design for the power supply requirements of a specific scientific research device (the neutral beam injection system of a magnetic confinement fusion experimental device).

[0086] Example 2 discloses a neutral beam injection system, wherein the suppression electrode power supply of the neutral beam injection system is composed of a power protection circuit for suppressing neutral beam arcing impact as described in Example 1.

[0087] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A power supply protection circuit for suppressing neutral beam arcing impact, characterized in that, The power supply is connected to the output protection circuit via a preprocessing circuit. The output protection circuit receives the pulsating DC voltage obtained after processing by the preprocessing circuit and filters and clamps the pulsating DC voltage to obtain a stable output voltage to supply the load. Along the current transmission direction, the output protection circuit includes a filter sub-circuit, an IGBT circuit, a secondary clamping protection sub-circuit, a buffer sub-circuit, and an output stage clamping protection sub-circuit arranged sequentially. The filter sub-circuit is used to receive the pulsating DC voltage and perform noise filtering, energy buffering and safe discharge processing on the pulsating DC voltage to output a purer, less rippled, and stable DC voltage that can safely discharge when the power is turned off. The IGBT circuit is used to receive the stable DC voltage and to provide overcurrent and overvoltage protection for the IGBT elements in the IGBT circuit during rapid turn-off. The output stage clamping protection sub-circuit is used to clamp the impulse voltage generated when high-voltage arcing discharge occurs at the load end, so that the voltage across the IGBT element is controlled within a safe range. The secondary clamping protection sub-circuit is used to perform a secondary clamping of the surge voltage when the output stage clamping protection sub-circuit fails to eliminate the surge voltage after the first clamping, so that the voltage across the IGBT element is controlled within a safe range. The buffer circuit is used to attenuate the surge voltage from the output stage clamp protection sub-circuit.

2. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, The filter sub-circuit includes a filter capacitor, a discharge resistor, and a discharge switch, wherein the filter capacitor is connected in parallel with a first series link that is connected in series with the discharge circuit and the discharge switch.

3. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, The IGBT circuit includes an IGBT element, an IGBT clamping arrester, an absorption resistor, and an absorption capacitor. The absorption resistor and absorption capacitor are connected in series to form an RC absorption protection sub-circuit. The RC absorption protection sub-circuit and the IGBT clamping arrester are connected in parallel. The two ends of the IGBT clamping arrester are located at the emitter and collector of the IGBT element. The collector of the IGBT element is connected to the filter sub-circuit, and the emitter of the IGBT element is connected to the secondary clamping protection sub-circuit.

4. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, The secondary clamping protection sub-circuit includes a protection surge arrester and a freewheeling diode connected in parallel. The protection surge arrester and the freewheeling diode are connected in parallel, and the anode of the freewheeling diode is connected to the IGBT circuit and the buffer circuit respectively, and the cathode of the freewheeling diode is connected to the filter sub-circuit and the buffer circuit respectively.

5. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 4, characterized in that, Two buffer sub-circuits are provided, and the two buffer circuits are respectively connected to the anode and cathode of the freewheeling diode. Each buffer sub-circuit includes a current-limiting resistor, a freewheeling resistor, and a short-circuit inductor. The current-limiting resistor is connected in series with a parallel link formed by the freewheeling resistor and the short-circuit inductor. The end of the current-limiting resistor away from the parallel link is connected to the secondary clamping protection sub-circuit, and the end of the parallel link away from the current-limiting resistor is connected to the output stage clamping protection sub-circuit.

6. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, The output stage clamping protection sub-circuit includes an output absorption capacitor, an output discharge resistor, and an output clamping surge arrester connected in parallel, and the output terminal of the output stage clamping protection sub-circuit is connected to the suppression electrode.

7. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, Along the current transmission direction, the preprocessing circuit includes an EMI circuit, a three-phase rectifier circuit, a full-bridge inverter circuit, a step-up transformer, and an uncontrolled rectifier circuit.

8. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, The power supply is a three-phase AC voltage.

9. A power supply protection circuit for suppressing neutral beam arcing impact according to claim 1, characterized in that, A current sensor is provided between the IGBT circuit and the secondary clamping protection sub-circuit.

10. A neutral beam injection system, characterized in that, The suppression electrode power supply of the neutral beam injection system consists of a power protection circuit for suppressing neutral beam arcing impact as described in any one of claims 1-9.

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