High-voltage pulse modulator based on multi-igbt series-parallel structure and control method thereof

Abstract

The application discloses a high-voltage pulse modulator based on a multi-IGBT series-parallel structure and a control method thereof, comprising a high-voltage modulation switch assembly, a control assembly, a heat dissipation assembly, a protection assembly and a monitoring assembly, the high-voltage modulation switch assembly adopts a composite topology of multi-branch parallel and multi-IGBT series in each branch and is configured with a dynamic voltage equalization buffer network; the control assembly adopts a two-stage isolated pulse transformer driving architecture to realize complete electrical isolation of high and low voltages and time sequence synchronization of driving signals of each branch; the heat dissipation assembly distinguishes low-voltage air cooling and high-voltage oil immersion type oil-water circulation heat exchange; the protection assembly integrates overcurrent striking, overvoltage and overtemperature protection submodules, adopts high-speed amplification and optical fiber isolation transmission, and the fault response time is less than or equal to 4 mu s; the monitoring assembly collects pulse voltage, pulse current and temperature data in real time and feeds back to the control assembly to form a closed-loop monitoring, and the application can stably output pulse high voltage above 120 kV and pulse large current above 80 A, and is suitable for a high-power microwave electron tube driving scene.

Description

Technical Field

[0001] This invention belongs to the field of pulse power and high-voltage power electronics technology, specifically a multi-IGBT series-parallel solid-state high-voltage pulse modulator and its control method, which is applicable to high-power microwave tube driving in particle accelerators, radar transmission systems, medical radiotherapy equipment, and industrial plasma heating devices. Background Technology

[0002] High-voltage pulse modulators are the core power supply equipment for high-power microwave tubes such as klystrons, traveling wave tubes, and magnetrons, and are widely used in critical equipment fields such as high-energy particle accelerators, pulse radar, linear accelerators for tumor radiotherapy, and industrial radio frequency heating. Early pulse modulators mostly used vacuum thyristors and hydrogen thyristors as main switching devices, which had drawbacks such as short lifespan, large trigger jitter, narrow pulse amplitude adjustment range, and high maintenance costs. With the iteration of wide-bandgap, high-power semiconductor devices, all-solid-state high-voltage pulse modulators based on IGBTs have gradually replaced vacuum tube solutions and become the mainstream development direction in the industry.

[0003] Due to the limitations of the voltage withstand and current carrying capacity of a single IGBT chip, single-tube or series-connected topologies with a small number of IGBTs can only achieve pulse outputs of tens of kilovolts, which cannot meet the requirements of high-power equipment with ultra-high pulse voltages of 120kV and above and pulse currents of 80A and above. To address this, existing technologies propose composite topologies with multiple IGBTs in series and multiple branches in parallel to improve the overall voltage withstand and peak output current. However, these topologies still face several technical bottlenecks and shortcomings in practical engineering applications. The dynamic voltage equalization performance of series-connected IGBTs is poor: relying solely on static voltage equalization resistors for voltage division, there is a lack of dynamic buffer network; the transmission delay of drive signals in each branch is inconsistent, the transient voltage division of the switch is unbalanced, and the device is prone to instantaneous overvoltage breakdown. Conventional low-voltage side compensation voltage equalization schemes have complex isolation structures and cannot be adapted to 100 kV insulation conditions.

[0004] Insufficient reliability of high-voltage side isolation drive: insufficient fiber optic direct drive output power, multi-channel isolated power supply drive is susceptible to high-voltage pulse electromagnetic interference, resulting in drive waveform distortion; single-stage pulse transformer isolation architecture cannot simultaneously meet the requirements of millisecond-level pulse flat top and hundred-kilovolt insulation withstand voltage.

[0005] Insufficient heat exchange capacity of the heat dissipation system: The upper limit of air-cooled heat dissipation power in the low-voltage circuit is low; the high-voltage components rely solely on natural cooling by oil immersion, and the concentrated arrangement of heat-generating components leads to local heat accumulation. There is no independent oil-water circulation heat exchange structure or multi-point temperature measurement mechanism, which cannot support the long-term continuous operation of the equipment at full load.

[0006] Slow fault protection response and weak anti-interference capability: The inrush current amplitude is high when the load is short-circuited by arcing. Traditional protection circuits use ordinary operational amplifiers and wired sampling transmission, with a response time greater than 10μs, which cannot achieve ultra-fast shutdown. The sampling circuit and the drive circuit are not completely electrically isolated, and electromagnetic interference can easily cause false triggering or failure to trigger the protection. There is no unified fiber optic isolation linkage architecture for overcurrent, overvoltage, and overtemperature protection.

[0007] Insufficient high-voltage insulation and electromagnetic compatibility performance: The high-voltage electric field is not equipotentially treated, which easily leads to corona discharge; the high-voltage devices are scattered, and electromagnetic radiation interferes with the sampling and control circuits; the monitoring elements lack high-voltage insulation packaging, making it difficult to directly collect multiple voltage, current, and temperature parameters on the high-voltage side, resulting in poor monitoring stability.

[0008] In summary, existing multi-IGBT series-parallel high-voltage pulse modulators cannot simultaneously achieve stable output of pulse voltage of 120kV and above and pulse current of 80A and above. They have systemic technical defects in dynamic voltage equalization, isolated drive, efficient heat dissipation, high-speed isolation protection, and high-voltage insulation monitoring, making it difficult to meet the requirements of long-term continuous operation of equipment such as accelerators, medical devices, and radar. Summary of the Invention

[0009] To address the technical shortcomings of existing multi-IGBT series-parallel high-voltage pulse modulators, such as dynamic voltage equalization imbalance in series switches, poor stability of high-voltage isolation drive, low heat dissipation efficiency, slow fault protection response, and insufficient high-voltage insulation and electromagnetic compatibility performance, this invention aims to provide a high-voltage pulse modulator based on a multi-IGBT series-parallel structure and its control method.

[0010] The technical solution adopted by the present invention to solve the technical problem is: a high-voltage pulse modulator based on a multi-IGBT series-parallel structure, used to drive high-frequency high-power electronic tubes such as klystrons, traveling wave tubes, and magnetrons, including a high-voltage modulation switching component, a control component, a heat dissipation component, a protection component, and a monitoring component; The high-voltage modulation switch assembly adopts a series-parallel composite topology with multiple branches in parallel and multiple IGBTs in series in each branch. Each IGBT branch is equipped with a dynamic voltage equalization buffer network, which improves the overall voltage withstand and current carrying capacity by relying on the series-parallel connection of multiple tubes. The control component adopts a two-stage isolation pulse transformer drive architecture, including a photoelectric conversion unit, a timing trigger unit, a waveform correction unit, and a push-pull drive unit. The external trigger optical signal is converted by photoelectric conversion and superimposed with a high-frequency carrier signal to generate a drive waveform, which is then transmitted to the high-voltage side IGBT drive circuit through two-stage pulse transformer isolation. After rectification, the IGBT switching drive level is generated. The heat dissipation components are divided into a low-pressure air-cooled heat dissipation unit and a high-pressure oil-immersed circulating heat exchange unit; the low-pressure air-cooled heat dissipation unit forces air cooling on the low-pressure power devices in the control circuit; the high-pressure oil-immersed circulating heat exchange unit is equipped with a sealed insulating oil tank, in which the high-pressure power devices are immersed in insulating heat-conducting oil, and is equipped with an oil circulation mechanism and an oil-water heat exchange mechanism. Through oil-water heat exchange, the heat of the high-pressure devices is continuously removed, and multiple temperature measurement points are set in the oil tank to achieve uniform temperature control throughout the entire area. The protection component integrates overcurrent arcing protection submodule, overvoltage protection submodule, and overtemperature protection submodule. Each protection submodule is equipped with a high-speed signal amplification unit, an electrical isolation unit, and an optical fiber signal transmission link. It collects corresponding operating condition signals through current sampling circuit, high voltage divider sampling circuit, and temperature sensing circuit, respectively. Fault signals are transmitted in optical isolation. The fault response speed is controlled within 4μs. In the fault state, all IGBT drive signals are simultaneously cut off. The monitoring component is equipped with a high-voltage pulse voltage acquisition unit, a pulse current acquisition unit, and a multi-point temperature acquisition unit. Each acquisition unit has the capability to sample high-voltage insulation, and it collects and uploads pulse voltage, pulse current, and multi-point oil temperature monitoring data to the control component in real time to form a closed-loop monitoring system.

[0011] Preferably, a high-voltage equalizing ring is provided on the outside of the high-voltage modulation switch assembly to balance the high-voltage electric field; each series IGBT branch is equipped with a voltage dividing resistor and a current limiting inductor to form a dynamic voltage equalizing buffer network to eliminate dynamic voltage imbalance during the series IGBT switching process; the high-voltage insulation structure of the whole machine meets the 120kV pulse insulation requirement.

[0012] Preferably, the control component is equipped with a logic superposition unit to superimpose the external trigger pulse with the high-frequency carrier square wave timing, and outputs a push-pull drive signal after the drive waveform is uniformly corrected by the waveform correction unit; the two-stage pulse transformer eliminates high and low voltage potential coupling, ensures that the transmission delay of the drive signal of all IGBT branches is consistent, and adapts to the millisecond-level pulse flat-top output condition.

[0013] Preferably, the high-pressure oil-immersed circulating heat exchange unit uses an insulated and pressure-resistant pipeline to connect the oil circulation mechanism and the oil-water heat exchange mechanism, and the heat exchange pipeline has the rated pulse high-voltage isolation capability of the whole machine; the IGBT module adopts a modular and uniform arrangement structure inside the oil tank to increase the heat dissipation contact area of ​​the device and suppress local heat accumulation.

[0014] Preferably, each protection submodule adopts a unified "sampling amplification-electrical isolation-fiber transmission" signal path architecture; the fault shutdown signal and system reset signal are transmitted as optical signals through the fiber optic transceiver link, and the strong and weak currents are completely isolated to avoid false triggering of protection caused by high voltage pulse electromagnetic interference.

[0015] Preferably, the current sampling element, high voltage divider sampling element, and temperature sensing element in the monitoring component are all encapsulated with high voltage insulation; the voltage acquisition unit has a bandwidth covering DC to radio frequency bands, and simultaneously acquires the main circuit pulse current and the electron tube filament power frequency current; multiple temperature sensing elements are distributed in different areas of the oil tank to achieve full-area temperature acquisition.

[0016] Preferably, the entire high-voltage power circuit of the machine is enclosed and oil-immersed, and is used in conjunction with equalizing rings and buffer absorption networks to suppress electromagnetic radiation from pulse discharge; the high-voltage switch, current-limiting inductor, voltage-dividing resistor, and filament transformer are integrated inside the sealed oil tank to reduce the external electromagnetic interference of the whole machine and make it suitable for the electromagnetic environment of particle accelerators, radar, and high-power high-voltage medical equipment.

[0017] The present invention also provides a control method for the above-mentioned high-voltage pulse modulator, comprising the following steps: S1. Synchronous isolation drive control steps: After photoelectric conversion, the external trigger optical signal is superimposed on the high-frequency carrier signal and the waveform is corrected to generate a symmetrical drive pulse; the drive signal is isolated and transmitted to the high-voltage side through a two-stage isolation pulse transformer, and after rectification, the synchronous drive level is output to synchronously control the unified conduction and turn-off of multiple branch series and parallel IGBTs. S2, High and low pressure coordinated heat dissipation control steps: The low pressure control loop adopts continuous forced air cooling; the high pressure side draws heat transfer oil from the oil tank through the oil circulation mechanism and sends it to the oil-water heat exchange mechanism for heat exchange and cooling before returning it to the oil tank; multi-point temperature sensing elements collect the temperature of the entire oil tank in real time, and the temperature data is uploaded to the control component. When the temperature exceeds the limit, the protection logic is triggered. S3, Multi-channel high-speed fiber optic fault protection steps: Real-time acquisition of three types of operating condition signals: main circuit current, DC high voltage, and oil tank temperature. After high-speed amplification and electrical isolation, these signals are converted into optical fault signals. Once any fault such as overcurrent arcing, overvoltage, or overtemperature is detected, the fiber optic link quickly outputs a shutdown signal to cut off all IGBT drives. After the fault is cleared, the fiber optic reset signal is received to restore the modulator to normal operation. S4. Full-domain parameter closed-loop monitoring steps: The high-voltage acquisition unit, pulse current acquisition unit, and multi-point temperature acquisition unit continuously acquire pulse voltage, pulse current, and multi-point temperature data of the oil tank. All monitoring data are transmitted back to the control components in real time to realize closed-loop monitoring of the whole machine's operating conditions.

[0018] Preferably, in step S1, each series IGBT branch relies on a voltage divider buffer network to achieve static and dynamic voltage equalization; the control component outputs a synchronous drive waveform with no timing deviation, eliminates the switching timing difference between different IGBT branches, suppresses the dynamic voltage unevenness of the series tubes, and stably outputs high-voltage and high-current pulses.

[0019] Preferably, step S3 configures a graded fault protection logic: setting the ignition overcurrent fault as the highest priority for rapid response; the overvoltage fault and the ignition fault are synchronously shut down; the over-temperature fault first executes a power reduction warning, and if the over-temperature continues, the entire machine is completely shut down; all fault signals are transmitted with optical isolation to isolate the electromagnetic interference of high voltage pulses to the protection circuit.

[0020] Compared with the prior art, the present invention has the following advantages: This invention employs a multi-IGBT series-parallel composite topology, relying on multiple IGBTs connected in series to improve withstand voltage and multiple branches connected in parallel to improve current carrying capacity. Combined with a dynamic voltage equalization buffer network to suppress transient overvoltage, it stably outputs pulse voltage of 120kV and above and pulse current of 80A and above, meeting the power supply requirements of high-power microwave tubes such as klystrons, traveling wave tubes, and magnetrons.

[0021] The two-stage pulse transformer isolation drive architecture of this invention achieves complete electrical isolation between high and low voltage. The external system trigger signal is superimposed and corrected with the high-frequency carrier and then synchronously output to all IGBT branches. The transmission delay of each drive signal is consistent and there is no switching timing deviation. There is no need for multi-channel isolated power supply on the high-voltage side, which greatly reduces the distortion effect of high-voltage pulse electromagnetic interference on the drive waveform.

[0022] The low-voltage power devices of this invention adopt forced air cooling, while the high-voltage power devices are immersed in insulating heat-conducting oil and equipped with an independent oil-water circulation heat exchange circuit to continuously remove the concentrated heat from the high-voltage circuit. Temperature sensing elements are arranged at multiple points in the oil tank to monitor the oil temperature over the entire area, avoiding local heat accumulation and supporting the equipment to work continuously at full load for a long time.

[0023] This invention adopts a unified high-speed amplification + optocoupler isolation + fiber optic signal transmission architecture for overcurrent / arc protection, overvoltage, and overtemperature protection channels. The response time for arcing fault protection is ≤4μs, which can quickly lock out all IGBTs in the instant of load arcing and short circuit. Strong and weak currents are completely isolated, eliminating the possibility of false triggering or failure to trigger due to high voltage pulse interference. Multiple types of faults are uniformly linked to shut down, effectively protecting the switching devices and the downstream microwave tube load.

[0024] The invention features a fully enclosed oil-immersed high-voltage circuit, paired with a high-voltage equalizing ring to balance the high-voltage electric field and eliminate the risk of corona discharge. Voltage, current, and temperature sampling elements are all encapsulated with high-voltage insulation, allowing direct acquisition of multiple operating parameters on the high-voltage side. High-voltage power devices are integrated into a sealed oil tank, significantly reducing external electromagnetic radiation and making it suitable for the harsh electromagnetic environments of particle accelerators, radar, and high-energy medical equipment.

[0025] The IGBT module of this invention features a modular and uniform arrangement, making assembly and maintenance convenient. The core topology and control architecture of this invention are compatible with similar power switching devices such as SiCMOSFETs, and the drive, heat dissipation, and protection architectures do not require significant modifications, resulting in strong scalability. Attached Figure Description

[0026] Figure 1 is the overall system block diagram of the high-voltage pulse modulator of the present invention; Figure 2 is the overall block diagram of the IGBT drive matching the high-voltage modulation switch assembly of the present invention; Figure 3 is the internal drive logic block diagram of the control assembly of the present invention; Figure 4 is a schematic diagram of the structural model of the heat dissipation system of the present invention; Figure 5 is the block diagram of the overcurrent / arcing protection function of the present invention; Figure 6 is the block diagram of the overvoltage protection function of the present invention; Figure 7 is the block diagram of the temperature protection function of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to explain the present invention, and are not intended to limit the protection scope of the present invention. Those skilled in the art can reproduce the present invention according to this specification without creative work.

[0028] This embodiment discloses a high-voltage pulse modulator based on a multi-IGBT series-parallel structure, with a pulse output peak voltage ≥ 120kV and a pulse peak current ≥ 80A, which is used to drive a klystron microwave tube, and the supporting control method is implemented synchronously.

[0029] Embodiment 1: Embodiment of the whole hardware of the high-voltage pulse modulator As shown in Figure 1 the high-voltage pulse modulator includes a high-voltage modulation switch assembly, a control assembly, a heat dissipation assembly, a protection assembly, and a monitoring assembly. External DC high voltage is input to the high-voltage modulation switch assembly, and the high-voltage modulation switch assembly converts the DC high voltage into pulsed high voltage; one path of the pulsed high voltage is output to the Mod_Anode anode modulation terminal of the klystron, and the other path is connected to the secondary side of the high-voltage isolation transformer; the secondary side of the high-voltage isolation transformer respectively outputs power supply voltages adapted to the Heater filament and Cathode cathode of the klystron. The control assembly is electrically connected with the high-voltage modulation switch assembly to output a synchronous isolation drive signal; the heat dissipation assembly realizes insulated heat dissipation by dividing high-voltage and low-voltage zones; the protection assembly collects current, high voltage and temperature signals, and quickly turns off all switches in a fault state; the monitoring assembly collects pulse voltage, pulse current and oil temperature data in real time and uploads them to the control assembly for closed-loop management and control.

[0030] The high-voltage modulation switch assembly in this embodiment adopts a series-parallel composite topology with multiple branches in parallel and multiple IGBTs in series in a single branch. This embodiment features three parallel modulation branches, each with 150 IGBTs connected in series, totaling 450 IGBTs. Each IGBT is equipped with a dynamic voltage equalization buffer network consisting of upper and lower voltage dividing resistors and limiting inductors to eliminate transient voltage imbalance during series IGBT switching. The overall insulation withstand voltage margin is designed to be 1.5 times the rated voltage, with a total withstand voltage range of 180kV to 204kV, meeting the requirements for 120kV pulse high-voltage output.

[0031] In this embodiment, a high-voltage equalizing ring is installed at the high-voltage end of the whole machine to balance the high-voltage electric field and suppress corona discharge; all IGBT modules are placed inside the sealed oil tank with a modular and uniform arrangement structure to increase the heat dissipation contact area and avoid local heat accumulation.

[0032] In this embodiment, the control component is implemented as follows: Figure 2 , Figure 3 As shown, the control component adopts a two-stage isolation pulse transformer drive architecture, including a photoelectric conversion unit (fiber optic head), a timing trigger unit (flip-flop), a logic superposition unit (logic gate circuit, function generator), a waveform correction unit (high-speed differential mode comparator), a push-pull drive unit (driver chip, MOS), and two-stage pulse transformers (isolation transformer, push-pull transformer).

[0033] In this embodiment, the external system input trigger optical signal undergoes photoelectric conversion via an optical fiber connector, and the function generator outputs a high-frequency carrier square wave. A logic gate circuit superimposes the trigger electrical signal and the high-frequency square wave timing sequence, sends it to a high-speed differential comparator to correct the drive waveform, and generates two symmetrical reverse drive pulses. The drive pulses are amplified by a push-pull MOS amplifier, isolated by a two-stage pulse transformer, and transmitted via a high-voltage line to the high-voltage side IGBT drive circuit. A full-wave rectifier unit is configured on the high-voltage side to rectify the isolated AC drive waveform into an IGBT DC drive level. The two-stage pulse transformer achieves complete electrical isolation between high and low voltage, ensuring consistent transmission delays for all IGBT branch drive signals, adapting to a 1.5ms pulse flat-top output condition.

[0034] In this embodiment, the heat dissipation component is implemented in a structure that is divided into a low-pressure air-cooled heat dissipation unit and a high-pressure oil-immersed circulating heat exchange unit.

[0035] Low-voltage air-cooled heat dissipation unit: The low-voltage power devices (push-pull MOS, driver chip) in the control component adopt direct-mount heat sinks and are equipped with forced air cooling by a fan.

[0036] High-pressure oil-immersed circulating heat exchange unit: The sealed oil tank is filled with insulating heat-conducting oil, and all high-voltage power devices (IGBT modules, voltage divider resistors, current-limiting inductors, filament transformers) are immersed in the insulating heat-conducting oil. The oil tank is equipped with an oil circulation mechanism (oil pump) and an oil-water heat exchange mechanism. The oil pump draws hot oil from the oil tank and sends it to the oil-water heat exchanger. After heat exchange is completed by cooling water, the cooling oil flows back to the oil tank to form a closed-loop oil circulation. Temperature sensing elements are distributed at multiple points in the oil tank. In this embodiment, one temperature sensing element is placed at each of the four corners of the oil tank to collect the oil temperature over the entire area and provide real-time feedback on the heat distribution status. The oil circulation pipeline adopts an insulated withstand voltage pipeline with a withstand voltage of 120kV to achieve high-voltage isolation of the heat exchange circuit.

[0037] In this embodiment, the protection component is implemented in a structure that integrates an overcurrent / arc protection submodule, an overvoltage protection submodule, and an overtemperature protection submodule. The three submodules adopt a unified architecture of "sampling circuit - high-speed signal amplification unit - high-speed optocoupler electrical isolation - fiber optic signal transmission link".

[0038] like Figure 5 Overcurrent / arcing protection: The current sampling loop is equipped with CT1 and CT2 current transformers to collect the pulse current of the main circuit in real time. The sampled signal is sent to the high-speed signal amplification unit for amplification, and after being isolated by high-speed optical coupler, it drives the fiber optic transmitter to output the fault optical signal. The fiber optic receiver receives the fault shutdown optical signal and the system reset optical signal. After the fault is triggered, all IGBT drive signals are cut off synchronously. The arcing fault response time is controlled within 4μs.

[0039] like Figure 6 Overvoltage protection: The upper and lower voltage divider resistors form a high-voltage DC sampling circuit to collect and output high-voltage pulses in real time. The sampling signal is converted into an optical fault signal after high-speed amplification and optocoupler isolation. The IGBT is synchronously blocked in case of overvoltage fault.

[0040] like Figure 7 Temperature protection: Multi-point PT100 temperature sensing elements collect oil temperature in the tank. The temperature sampling signal is sent to a high-speed signal amplification unit. When the oil temperature exceeds the limit, a shutdown light signal is output.

[0041] All fault signals and reset signals are transmitted via optical signals, with complete isolation between strong and weak currents, avoiding false triggering or failure to trigger protection caused by high-voltage pulse electromagnetic interference.

[0042] In this embodiment, the monitoring component is implemented with a structure that includes a high-voltage pulse voltage acquisition unit, a pulse current acquisition unit, and a multi-point temperature acquisition unit. All sampling elements are encapsulated with high-voltage insulation.

[0043] In this embodiment, the high-voltage pulse voltage acquisition unit uses a wide-band high-voltage probe with a detection bandwidth covering DC to 80MHz, suitable for 50Hz, 1.5ms flat-top 120kV pulse voltage acquisition; the pulse current acquisition unit is equipped with a pulse current transformer, which independently acquires the 80A pulse total current of the main circuit and the filament power frequency current in two separate channels, with the two sampling circuits being mutually insulated; the multi-point temperature acquisition unit uses four PT100 sensing elements placed at the four corners of the oil tank, and the acquired signals are aggregated to the temperature transmitter module and uniformly uploaded to the control component.

[0044] Example 2: High-voltage pulse modulator control method This embodiment describes the control method corresponding to the device in Embodiment 1, which includes four synchronous execution steps: S1. Synchronous Isolation Drive Control Steps The external trigger optical signal is converted by photoelectric conversion in the fiber optic head and superimposed with the high-frequency carrier square wave output by the function generator. The waveform is corrected by a high-speed differential mode comparator to generate two symmetrical drive pulses. The drive pulses are transmitted to the high-voltage side through high- and low-voltage isolation by a two-stage isolation pulse transformer. After full-wave rectification on the high-voltage side, a synchronous drive level is output, which synchronously controls the unified conduction and cutoff of the three parallel IGBT series branches. Each series IGBT relies on a dynamic voltage equalization buffer network composed of voltage divider resistors and limiting inductors to achieve static and dynamic voltage equalization. The control component outputs a timing-free drive waveform, eliminates branch switching timing differences, and stably outputs a 120kV / 80A pulse.

[0045] S2, High and Low Voltage Coordinated Heat Dissipation Control Steps The low-pressure control circuit fan runs continuously, providing forced air cooling for the low-pressure power devices; the oil pump continuously draws heat transfer oil from the oil tank and sends it to the oil-water heat exchanger for water cooling, and the cooling oil flows back to the oil tank; four PT100 sensors collect the oil temperature at the four corners of the oil tank in real time, and the temperature transmitter module summarizes the temperature data and uploads it to the control component; when the oil temperature at any point exceeds the standard, the over-temperature protection logic is directly triggered.

[0046] S3, Multi-channel high-speed fiber optic fault protection steps CT1 and CT2 collect the main circuit current in real time, the voltage divider resistor samples the DC high voltage in real time, and four PT100s synchronously collect the oil temperature. The three types of sampled signals are amplified by a high-speed signal amplifier unit and converted into optical fault signals via high-speed optocoupler isolation. A graded fault protection logic is set: ignition overcurrent faults have the highest priority, with a measured shutdown response time of 2.7μs; overvoltage faults and ignition faults are synchronously linked for shutdown; overtemperature faults first trigger a power reduction warning, and if the oil temperature rises above 30K and continues to rise, then all IGBTs are completely shut down; after the fault is cleared, the system sends a fiber optic reset signal, and the modulator returns to normal operation. All fault signals are transmitted with optical isolation to prevent electromagnetic interference from high-voltage pulses to the protection circuit.

[0047] S4. Steps for Closed-Loop Monitoring of Global Parameters The high-voltage pulse voltage acquisition unit, pulse current acquisition unit, and four-channel PT100 temperature acquisition unit continuously acquire pulse voltage, pulse current, and multi-point oil temperature data. All monitoring data are transmitted back to the control components in real time, realizing closed-loop monitoring of the overall machine's operating conditions.

[0048] Example 3: Alternative Extended Implementation (Replacement of Power Devices, Drivers, Heat Dissipation, and Protection Circuits) Power switching device replacement implementation: Replace IGBT with SiCMOSFET. The rest of the device's drive, heat dissipation, protection, and monitoring architecture does not need to be changed. Only the corresponding device drive level parameters need to be matched to achieve the same high voltage and high current output performance. Driver architecture replacement implementation: The two-stage pulse transformer driver can be replaced with a fiber optic isolated driver or a capacitor isolated driver. Only the signal conversion unit is adjusted, while the protection and heat dissipation structures remain unchanged. Heat dissipation expansion implementation: The oil-water heat exchange structure is eliminated, and a full oil-cooled circulation heat dissipation or air-cooled + oil-cooled hybrid heat dissipation is adopted. Only the heat exchange mechanism is adjusted, and the basic structure of multi-point temperature measurement and oil tank immersion remains unchanged. Protection circuit expansion implementation: Replace the high-speed operational amplifier with a high-speed comparator or FPGA to realize signal amplification and fault detection, while keeping the fiber optic isolated transmission architecture unchanged.

[0049] The above descriptions are merely some specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, substitutions, or improvements made based on the technical concept of the present invention using the same or equivalent technical means should be considered to fall within the scope of protection of the present invention.

Claims

1. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure, used to drive high-frequency, high-power electron tubes such as klystrons, traveling wave tubes, and magnetrons, comprising a high-voltage modulation switch assembly, a control assembly, a heat dissipation assembly, a protection assembly, and a monitoring assembly; the high-voltage modulation switch assembly receives a DC high-voltage input and converts it into a pulse high-voltage, one path of which is output to the anode modulation terminal of the electron tube, and the other path is connected to the secondary winding of a high-voltage isolation transformer, the secondary winding of which outputs power to the electron tube filament and cathode; the control assembly is electrically connected to the high-voltage modulation switch assembly and outputs a synchronous isolated drive signal; the heat dissipation assembly provides insulation and heat dissipation for the high and low voltage components of the entire unit; the protection assembly collects the operating electrical parameters and temperature parameters of the entire unit and quickly shuts off the switch in case of a fault; the monitoring assembly collects output pulse voltage, pulse current, and equipment temperature operating condition data in real time; characterized in that: The high-voltage modulation switch assembly adopts a series-parallel composite topology with multiple branches in parallel and multiple IGBTs in series in each branch. Each IGBT branch is equipped with a dynamic voltage equalization buffer network. The series-parallel connection of multiple tubes improves the overall withstand voltage and current carrying capacity, meeting the output requirements of pulse high voltage above 120kV and pulse high current above 80A. The control component adopts a two-stage isolation pulse transformer drive architecture, including a photoelectric conversion unit, a timing trigger unit, a waveform correction unit, and a push-pull drive unit. The external trigger light signal is converted by photoelectric conversion and superimposed with a high-frequency carrier signal to generate a drive waveform. It is then transmitted to the high-voltage side IGBT drive circuit through two-stage pulse transformer isolation. After rectification, it generates the IGBT switch drive level, realizing complete electrical isolation between high and low voltage and timing synchronization of drive signals in each branch. The heat dissipation components are divided into a low-pressure air-cooled heat dissipation unit and a high-pressure oil-immersed circulating heat exchange unit; the low-pressure air-cooled heat dissipation unit forces air cooling on the low-pressure power devices in the control circuit; the high-pressure oil-immersed circulating heat exchange unit is equipped with a sealed insulating oil tank, in which the high-pressure power devices are immersed in insulating heat-conducting oil, and is equipped with an oil circulation mechanism and an oil-water heat exchange mechanism. Through oil-water heat exchange, the heat of the high-pressure devices is continuously removed, and multiple temperature measurement points are set in the oil tank to achieve uniform temperature control throughout the entire area. The protection component integrates overcurrent arcing protection submodule, overvoltage protection submodule, and overtemperature protection submodule. Each protection submodule is equipped with a high-speed signal amplification unit, an electrical isolation unit, and an optical fiber signal transmission link. It collects corresponding operating condition signals through current sampling circuit, high voltage divider sampling circuit, and temperature sensing circuit, respectively. Fault signals are transmitted in optical isolation. The fault response speed is controlled within 4μs. In the fault state, all IGBT drive signals are simultaneously cut off. The monitoring component is equipped with a high-voltage pulse voltage acquisition unit, a pulse current acquisition unit, and a multi-point temperature acquisition unit. Each acquisition unit has the capability to sample high-voltage insulation, and it collects and uploads pulse voltage, pulse current, and multi-point oil temperature monitoring data to the control component in real time to form a closed-loop monitoring system.

2. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, The high-voltage modulation switch assembly is externally equipped with a high-voltage equalizing ring to balance the high-voltage electric field; each series IGBT branch is equipped with a voltage dividing resistor and a current limiting inductor to form a dynamic voltage equalizing buffer network to eliminate dynamic voltage imbalance during the series IGBT switching process; the high-voltage insulation structure of the whole machine meets the withstand voltage requirement of 120kV pulse insulation.

3. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, The control component has a built-in logic superposition unit that superimposes the external trigger pulse with the high-frequency carrier square wave timing. After the waveform correction unit uniformly corrects the drive waveform, the push-pull drive signal is output. The two-stage pulse transformer eliminates high and low voltage potential coupling, ensuring that the transmission delay of the drive signal of all IGBT branches is consistent, and adapting to the millisecond-level pulse flat-top output condition.

4. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, The high-pressure oil-immersed circulating heat exchange unit uses insulated and pressure-resistant pipelines to connect the oil circulation mechanism and the oil-water heat exchange mechanism. The heat exchange pipelines have the rated pulse high-voltage isolation capability of the whole machine. The IGBT modules adopt a modular and uniform arrangement structure inside the oil tank to increase the heat dissipation contact area of ​​the devices and suppress local heat accumulation.

5. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, Each protection submodule adopts a unified "sampling amplification-electrical isolation-fiber transmission" signal path architecture; fault shutdown signals and system reset signals are transmitted as optical signals through fiber optic transceiver links, with complete isolation between strong and weak currents, avoiding false triggering of protection caused by high-voltage pulse electromagnetic interference.

6. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, The monitoring components include current sampling elements, high-voltage divider sampling elements, and temperature sensing elements, all of which are encapsulated in high-voltage insulation. The voltage acquisition unit has a bandwidth covering DC to radio frequency bands, and simultaneously acquires the main circuit pulse current and the electron tube filament power frequency current. Multiple temperature sensing elements are distributed in different areas of the oil tank to achieve full-area temperature acquisition.

7. A high-voltage pulse modulator based on a multi-IGBT series-parallel structure according to claim 1, characterized in that, The entire high-voltage power circuit of the machine is enclosed and oil-immersed, with equalizing rings and buffer absorption networks to suppress electromagnetic radiation from pulse discharge. The high-voltage switch, current-limiting inductor, voltage-dividing resistor, and filament transformer are integrated inside the sealed oil tank to reduce the external electromagnetic interference of the whole machine, making it suitable for the electromagnetic environment of particle accelerators, radar, and high-power high-voltage medical equipment.

8. A control method for a high-voltage pulse modulator based on a multi-IGBT series-parallel structure, applied to the high-voltage pulse modulator according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Synchronous isolation drive control steps: After photoelectric conversion, the external trigger optical signal is superimposed on the high-frequency carrier signal and the waveform is corrected to generate a symmetrical drive pulse; the drive signal is isolated and transmitted to the high-voltage side through a two-stage isolation pulse transformer, and after rectification, the synchronous drive level is output to synchronously control the unified conduction and turn-off of multiple branch series and parallel IGBTs. S2, High and low pressure coordinated heat dissipation control steps: The low pressure control loop adopts continuous forced air cooling; the high pressure side draws heat transfer oil from the oil tank through the oil circulation mechanism and sends it to the oil-water heat exchange mechanism for heat exchange and cooling before returning it to the oil tank; multi-point temperature sensing elements collect the temperature of the entire oil tank in real time, and the temperature data is uploaded to the control component. When the temperature exceeds the limit, the protection logic is triggered. S3, Multi-channel high-speed fiber optic fault protection steps: Real-time acquisition of three types of operating condition signals: main circuit current, DC high voltage, and oil tank temperature. After high-speed amplification and electrical isolation, these signals are converted into optical fault signals. Once any fault such as overcurrent arcing, overvoltage, or overtemperature is detected, the fiber optic link quickly outputs a shutdown signal to cut off all IGBT drives. After the fault is cleared, the fiber optic reset signal is received to restore the modulator to normal operation. S4. Full-domain parameter closed-loop monitoring steps: The high-voltage acquisition unit, pulse current acquisition unit, and multi-point temperature acquisition unit continuously acquire pulse voltage, pulse current, and multi-point temperature data of the oil tank. All monitoring data are transmitted back to the control components in real time to realize closed-loop monitoring of the whole machine's operating conditions.

9. A high-voltage pulse modulator control method based on a multi-IGBT series-parallel structure according to claim 8, characterized in that, In step S1, each series IGBT branch relies on a voltage divider buffer network to achieve static and dynamic voltage equalization; the control component outputs a synchronous drive waveform with no timing deviation, eliminates the switching timing difference between different IGBT branches, suppresses the dynamic voltage unevenness of the series tubes, and stably outputs high-voltage and high-current pulses.

10. A high-voltage pulse modulator control method based on a multi-IGBT series-parallel structure according to claim 8, characterized in that, Step S3: Configure graded fault protection logic: Set the ignition overcurrent fault as the highest priority for fast response; the overvoltage fault and the ignition fault are synchronously shut down. In case of an over-temperature fault, a power reduction warning will be issued first, and if the over-temperature continues, the entire machine will be shut down. All fault signals are transmitted with optical isolation to prevent electromagnetic interference from high-voltage pulses to the protection circuit.

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