Hybrid pulse discharge valve group

Abstract

The application discloses a hybrid pulse discharge valve group, which comprises a pulse power thyristor and a fast recovery diode (FRD). The pulse power thyristor and the fast recovery diode (FRD) are connected in series to form the hybrid pulse discharge valve group, the fast recovery diode (FRD) is used to assist the valve group to be turned off, and a reverse impact voltage is applied to the fast recovery diode (FRD) which has stronger endurance. The valve group can reduce the number of pulse thyristors used, reduce the installation height, and has the characteristics of ultra-low inductance and compact size under the condition of realizing predetermined pulse discharge parameters.

Description

Technical Field

[0001] This invention relates to the field of high-voltage, high-current pulse power supply technology, and in particular to a hybrid pulse discharge valve group. Background Technology

[0002] The compact ring injection device utilizes a high-current pulsed power supply to inject excited plasma into the target device at high speed. This technology has broad application prospects in fusion device fueling and plasma sources. The pulsed power supply needs to output hundreds of kiloamperes of peak current within approximately ten microseconds at a voltage of 10 kV, while also possessing stable repetition rate performance. Using pulsed thyristor valve assemblies to achieve solid-state power supply can effectively reduce the device's failure rate and extend its service life. However, existing pulsed thyristors, under ultra-high current change rates, must withstand megawatt-level power surges during their reverse recovery process. The thermal failure risk faced by pulsed thyristors during the turn-on and on-state phases of discharge is far less than that during the reverse recovery process. This means that pulsed valve assemblies designed according to device ratings often fail to achieve the intended maximum pulse current. The traditional parallel RC buffer branch method for valve assemblies has limited effectiveness under such extreme pulse parameters.

[0003] In the design of high-voltage, high-current pulse power supplies, the reverse recovery characteristics of power transistors are crucial. Reverse recovery during the turn-off phase suppresses pulse width and increases voltage and current stress on circuit components. When the reverse power surge experienced by the power transistor exceeds a certain limit, device failure may occur. Common high-power pulse thyristors have relatively low single-transistor reverse peak power handling capacity; extremely high reverse overvoltage spikes are the primary cause of device damage. Existing valve group devices, employing multiple power transistors in series, do not effectively reduce the impact of reverse power surges. Furthermore, increasing the number of power transistors leads to excessively large valve group sizes and makes stray parameters difficult to control. Summary of the Invention

[0004] The purpose of this invention is to provide a hybrid pulse discharge valve assembly that can reduce the number of pulse thyristors used and lower the installation height while achieving predetermined pulse discharge parameters, and also has the characteristics of ultra-low inductance and compact size.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A hybrid pulse discharge valve assembly, comprising a pulse power thyristor and a fast recovery diode (FRD), wherein:

[0007] A hybrid pulse discharge valve group is formed by connecting a pulse power thyristor and a fast recovery diode (FRD) in series. The FRD is used to assist in the valve group's turn-off, so that the reverse impulse voltage is applied to the faster recovery diode FRD, which has a stronger withstand capability. Specifically:

[0008] When the valve group voltage is U0, the reverse charge of the thyristor with arbitrary pulse power is Q. Gi When the thyristor is turned off, the voltage U is calculated using the following formula (1). i :

[0009]

[0010] Where n is the number of thyristors; β is the reverse recovery overshoot coefficient; This represents the average reverse recovery charge of the thyristor.

[0011] Assume the maximum reverse recovery charge difference between the two thyristors is ΔQ rr Then the maximum voltage difference between thyristor stages is:

[0012]

[0013] The maximum voltage that the thyristor withstands at the turn-off moment is calculated by the following formula (3):

[0014]

[0015] In reverse recovery charge Q rr The smallest thyristor withstands the largest turn-off voltage because the fast recovery diode (FRD) has a small Q during reverse recovery. rr The depletion time of the stored charge in a fast recovery diode (FRD) is much shorter than that of a thyristor, so the FRD can turn off the main circuit and withstand the reverse impulse voltage earlier, while the smaller Q... rr The generated reverse recovery current is small, thus reducing the reverse power impact on the hybrid pulse discharge valve group.

[0016] As can be seen from the technical solution provided by the present invention, the valve group can reduce the number of pulse thyristors used and reduce the installation height while achieving the predetermined pulse discharge parameters, and at the same time has the characteristics of ultra-low inductance and compact size. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the hybrid pulse discharge valve group provided in an embodiment of the present invention;

[0019] Figure 2 This is an enlarged schematic diagram of the valve assembly structure;

[0020] Figure 3 This is a schematic diagram of one implementation structure of the hybrid pulse discharge valve group described in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, and do not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] like Figure 1 The diagram shown is a structural schematic of a hybrid pulse discharge valve assembly provided in an embodiment of the present invention. Figure 2 The image shown is an enlarged schematic diagram of the valve assembly structure, combined with... Figure 1 and 2 The hybrid pulse discharge valve group includes a pulse power thyristor and a fast recovery diode (FRD), wherein:

[0023] The thyristor operating condition test results show that the thyristor whose reverse charge Qrr is depleted first will turn off first and begin to withstand the reverse voltage. A larger Qrr results in a larger peak reverse recovery current and a longer recovery time. By connecting a pulsed power thyristor and a fast recovery diode (FRD) in series to form a hybrid pulsed discharge valve group, the FRD is used to assist in the valve group's turn-off. This allows the reverse surge voltage to act on the more resilient FRD, improving the valve group's performance. Specifically:

[0024] When the valve group voltage is U0, the reverse charge of the thyristor with arbitrary pulse power is Q. Gi When the thyristor is turned off, the voltage U is calculated using the following formula (1). i :

[0025]

[0026] Where n is the number of thyristors; β is the reverse recovery overshoot coefficient; This represents the average reverse recovery charge of the thyristor.

[0027] Assume the maximum reverse recovery charge difference between the two thyristors is ΔQ rr Then the maximum voltage difference between thyristor stages is:

[0028]

[0029] The maximum voltage that the thyristor withstands at the turn-off moment is calculated by the following formula (3):

[0030]

[0031] In reverse recovery charge Q rr The smallest thyristor withstands the largest turn-off voltage because the fast recovery diode (FRD) has a small Q during reverse recovery. rr The depletion time of the stored charge in a fast recovery diode (FRD) is much shorter than that of a thyristor, so the FRD can turn off the main circuit and withstand the reverse impulse voltage earlier, while the smaller Q... rr The generated reverse recovery current is small, thus reducing the reverse power impact on the hybrid pulse discharge valve group.

[0032] In the specific implementation, the number of pulse power thyristors is determined in the following way:

[0033] When determining the number of pulse power thyristors, the peak operating voltage of the valve group branch, the repetitive peak voltage of the power transistors, various fluctuation factors of the applied voltage, and the necessary voltage design margin must be considered. The number of pulse power thyristors n connected in series in the valve group. d It is calculated from the following formula (4):

[0034]

[0035] In the formula, K cu U is the overpressure impact coefficient. AM K represents the peak operating voltage that the valve assembly withstands. b K is the voltage rise factor; Au For voltage design margin; K u U is the equalization pressure coefficient; RM This is the rated repetitive peak voltage of the power transistor.

[0036] The number of series and parallel branches of the fast recovery diode FRD are determined as follows:

[0037] To minimize the impact of reverse power surges and protect the power transistors, the FRD in the main circuit, which is turned off first, must safely withstand reverse voltage surges. Considering that the FRD's voltage withstand capability is stronger than that of the power transistors, and to avoid redundant design, the number of series-connected fast recovery diodes (FRDs) selected is limited to N. FRD The number of thyristors equal to the pulse power n d The quantity, i.e., N FRD =n d ;

[0038] For the valve group of the pulse power supply in this invention, the peak reverse recovery current can reach tens of kiloamperes. Connecting only one branch may exceed the current withstand capability of the FRD, which can easily damage the device. Moreover, the FRD has a small reverse recovery charge and generates a small reverse recovery current. Designing parallel FRD branches can not only shunt the current but also effectively reduce the impact of reverse power surges. The number of parallel branches m of the fast recovery diode FRD is calculated by the following formula (5):

[0039]

[0040] In the formula, I A(AV) I is the average current of the parallel branches; T(AV) K represents the average reverse recovery current that the FRD can withstand. R K is the equipment current overload factor; A1 Safety margin designed for current; K C1 K is the device overload factor; K1 is the current sharing factor; K θ This represents the ambient temperature coefficient.

[0041] Furthermore, series-connected thyristors can experience uneven voltage distribution due to factors such as turn-on time deviation and reverse recovery time difference. Therefore, it is necessary to properly distribute the voltage among the series-connected thyristors to prevent damage to a single device due to overvoltage. A resistor, namely the buffer resistor R, is connected in parallel across the pulse power thyristor. d A capacitor, namely the buffer capacitor C, is connected in parallel across the fast recovery diode FRD. d This constitutes a voltage equalization circuit to achieve dynamic voltage equalization, such as... Figure 2 As shown, according to the principle of charge balance, the buffer capacitor C d It should meet the following requirements:

[0042]

[0043] In the formula, I FRD The current in the FRD branch is Δt. on For FRD conduction time difference; U max This is the maximum voltage that the FRD can withstand;

[0044] For the buffer capacitor C d and buffer resistor R d The value must also satisfy the following formula:

[0045] R d C d ≤τ (7)

[0046] τ is the discharge time of the valve assembly, ensuring that the buffer capacitor C is within the discharge time. d The charge on the buffer resistor R d The release is complete, and the buffer capacitor C...d The higher the value, the better the pressure equalization effect.

[0047] like Figure 3 The diagram shown is a schematic representation of one implementation structure of the hybrid pulse discharge valve group according to an embodiment of the present invention. The number of parallel branches of the fast recovery diode (FRD) is m=4, resulting in four branches. Each branch surrounds the pulse power thyristor branch at a 90° angle. The overall structure of the valve group from top to bottom is as follows:

[0048] 1. Coaxial cable: Used as a connecting wire in the circuit to connect various modules;

[0049] 2. Support column: Serves as a supporting and fixing component for the press-fit structure;

[0050] 3. Press-fit base: The power transistor is fixed above and below the power transistor, and pressure is applied by the support columns to make the power transistor fit tightly together and form a multi-stage series high-power switching device.

[0051] 4. Fast recovery diode (FRD): During the power transistor turn-off phase, it is mainly used to withstand reverse voltage surges;

[0052] 5. Pulse power thyristor: In the valve group branch, it is controlled by an external trigger circuit to switch the discharge circuit on and off.

[0053] The above structure has strong current carrying capacity, high voltage withstand level, and reverse recovery power is almost evenly distributed to each FRD branch. At the same time, it reduces the installation height, is compact in size, and optimizes the stray parameters of the entire structure to the greatest extent.

[0054] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0055] In summary, the valve assembly described in the embodiments of the present invention has the following advantages:

[0056] 1. The reverse recovery characteristics of the power transistor during the turn-off phase in the valve group are considered, which effectively reduces the impact of reverse power surge, protects the safety of the power transistor, and improves the performance of the pulse power supply.

[0057] 2. The design of the valve group hybrid structure makes full use of the inherent conditions of the coaxial structure, and has the characteristics of ultra-low inductance and compact structure.

[0058] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A hybrid pulse discharge valve assembly, characterized in that, The hybrid pulse discharge valve group includes a pulse power thyristor and a fast recovery diode (FRD), wherein: A hybrid pulse discharge valve group is formed by connecting a pulse power thyristor and a fast recovery diode (FRD) in series. The FRD is used to assist in the valve group's turn-off, so that the reverse impulse voltage is applied to the faster recovery diode FRD, which has a stronger withstand capability. Specifically: When the valve group voltage is U0, the reverse charge of the thyristor with arbitrary pulse power is Q. Gi When the thyristor is turned off, the voltage U is calculated using the following formula (1). i : （1） Where n is the number of thyristors; β is the reverse recovery overshoot coefficient; This represents the average reverse recovery charge of the thyristor. Assume the maximum reverse recovery charge difference between the two thyristors is ∆Q rr Then the maximum voltage difference between thyristor stages is: （2） The maximum voltage that the thyristor withstands at the turn-off moment is calculated by the following formula (3): （3） In reverse recovery charge Q rr The smallest thyristor withstands the largest turn-off voltage because the fast recovery diode (FRD) has a small Q during reverse recovery. rr The depletion time of the stored charge in a fast recovery diode (FRD) is much shorter than that of a thyristor, so the FRD can turn off the main circuit and withstand the reverse impulse voltage earlier, while the smaller Q... rr The generated reverse recovery current is small, so the reverse power impact borne by the hybrid pulse discharge valve group is reduced. The number of pulse power thyristors is determined as follows: The number n of pulse power thyristors connected in series in the valve group d It is calculated from the following formula (4): （4） In the formula, K cu U is the overpressure impact coefficient; AM K represents the peak operating voltage that the valve assembly withstands. b K is the voltage rise factor; Au For voltage design margin; K u U is the equalization pressure coefficient; RM This is the rated repetitive peak voltage of the power transistor; The number of series and parallel branches of the fast recovery diode FRD are determined as follows: The number N of the selected series fast recovery diodes (FRDs) FRD The number of thyristors equal to the pulse power n d The quantity, that is: ; The number of parallel branches m of the fast recovery diode FRD is calculated by the following formula (5): （5） In the formula, I A（AV） I is the average current of the parallel branches; T（AV） K represents the average reverse recovery current that the FRD can withstand. R K is the equipment current overload factor; A1 Safety margin designed for current; K C1 K is the device overload factor; K1 is the current sharing factor; K Ѳ This refers to the ambient temperature coefficient. The overall structure of the valve assembly, from top to bottom, is as follows: Coaxial cable: used as a connecting wire in the circuit to connect various modules; Support column: a supporting and fixing component for the press-fit structure; Press-fit base: The power transistor is fixed above and below the power transistor, and pressure is applied by the support columns to make the power transistor fit tightly together and form a multi-stage series high-power switching device. Fast recovery diode (FRD): Used to withstand reverse voltage surges during the power transistor's turn-off phase; Pulse power thyristor: In the valve group branch, it is controlled by an external trigger circuit to switch the discharge circuit on and off.

2. The hybrid pulse discharge valve assembly according to claim 1, characterized in that, A resistor, namely a buffer resistor R, is connected in parallel across the two ends of the pulse power thyristor. d A capacitor, namely the buffer capacitor C, is connected in parallel across the fast recovery diode FRD. d This constitutes a voltage equalization circuit to achieve dynamic voltage equalization. Based on the principle of charge balance, the buffer capacitor C... d Should meet: （6） In the formula, I FRD The current in the FRD branch; For FRD conduction time difference; U max This is the maximum voltage that the FRD can withstand; For the buffer capacitor C d and buffer resistor R d The value must also satisfy the following formula: （7） τ is the discharge time of the valve assembly, ensuring that the buffer capacitor C is within the discharge time. d The charge on the buffer resistor R d Release complete.

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