An ultra-low inductance coaxial valve block structure

Abstract

The application discloses a kind of ultra-low inductance coaxial valve group structures, the coaxial valve group structure includes crimping base, power tube, support column, copper adapter, shielding layer adapter in turn from bottom to top, power tube is fixed by two crimping bases up and down, support column is set between two crimping bases up and down, power tube is tightly connected by the pressure exerted by support column together, constitute multistage series high-power switching device;Copper adapter is designed with clamping groove structure on copper disc;The shielding layer of coaxial cable in upper end is fixed by the thread clamping groove of shielding layer adapter;Support column is also installed between shielding layer adapter and upper crimping base, the support column is not only used as the supporting and fixing part of crimping structure, but also as the current return path of coaxial structure.The structure optimizes the stray inductance of valve group module, and improves the connection mode between the load, which can effectively reduce the stray inductance of valve group module, improve pulse current amplitude and di / dt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage and high-current pulse power supply design, and particularly relates to a coaxial valve group structure with ultra-low inductance. BACKGROUND

[0002] A compact ring injection system generally adopts a high-current pulse power supply, uses electromagnetic force to emit high-speed compact ring plasma, and has wide application prospects in the fields of fusion charging and plasma sources, etc. The pulse power supply works on a microsecond time scale. The existing pulse power supply system mainly uses a pilot tube as a switching device to realize high-amplitude and narrow pulse width pulse discharge. However, due to the poor stability and easy damage of the pilot tube, it is difficult to realize the high-frequency discharge. Therefore, applying a solid-state switching tube to a high-power pulse power supply is the current development trend.

[0003] In the design process of a high-voltage and high-current pulse power supply, the wiring mode and structure of a device have a great influence on the stray inductance of a circuit, and the stray inductance in the circuit will inhibit the output pulse current amplitude and pulse width. The commonly used laminated busbar connection mode is difficult to be applied to the design of a high-voltage and high-current pulse power supply due to insufficient insulation. The existing technology usually cascades and crimps multiple switching devices into a switching valve group. The valve group structure of the crimping type device has a large volume and the stray inductance is difficult to control, so that the required pulse current amplitude and di / dt cannot be realized, and the crimping structure is not conducive to the connection with a load coaxial gun. SUMMARY

[0004] The purpose of the present application is to provide a coaxial valve group structure with ultra-low inductance, which optimizes the stray inductance of the valve group module and improves the connection mode with the load, so as to effectively reduce the stray inductance of the valve group module and improve the pulse current amplitude and di / dt.

[0005] The purpose of the present application is realized by the following technical solutions:

[0006] A coaxial valve group structure with ultra-low inductance comprises, from bottom to top, a crimping base, a power tube, a support column, a copper adapter, and a shielding layer adapter, wherein:

[0007] The power tube is fixed by the upper and lower crimping bases, and a support column is arranged between the upper and lower crimping bases. The power tube is tightly connected by the common pressure applied by the support column, thereby forming a multi-stage series high-power switching device.

[0008] The power tube serves as the core device of the power supply and functions as a controllable switch to control the output of the pulse power supply.

[0009] The copper adapter is installed on the upper crimping base, and a clamping groove structure is designed on the copper disc of the copper adapter for connecting the copper core of the upper end coaxial cable, and the copper cores of multiple coaxial cables can be connected in parallel;

[0010] The shielding layer adapter is installed above the copper adapter, and the shielding layer of the upper end coaxial cable is fixed through the threaded clamping groove of the shielding layer adapter, and the shielding layers of multiple coaxial cables are connected in parallel;

[0011] Supporting columns are also installed between the shielding layer adapter and the upper crimping base, which not only serve as supporting and fixing parts of the crimping structure, but also serve as current return paths of the coaxial structure, that is, the current flows from the coaxial cable to the power tube and returns to the coaxial cable through the supporting columns;

[0012] The power tube is also connected to an RC buffer module, which is used to reduce the reverse recovery power. When the switch is turned off, the RC buffer module suppresses the off voltage and current peak, thereby avoiding damage to the power tube due to excessive reverse power.

[0013] The RC buffer module is connected to a control unit, and a trigger signal is output through the control unit to control the conduction of the power tube.

[0014] As can be seen from the above technical solutions of the present application, the above structure optimizes the stray inductance of the valve group module and improves the connection mode with the load, which can effectively reduce the stray inductance of the valve group module and increase the pulse current amplitude and di / dt. The coaxial structure design fully utilizes the conditions of the crimping structure itself without introducing additional parts. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0016] Figure 1 The schematic diagram of the ultra-low inductance coaxial valve group structure provided by the embodiments of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments, which do not constitute a limitation on the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0018] As Figure 1 The application provides a coaxial valve group structure with ultra-low inductance, which comprises, from bottom to top, a crimping base, a power tube, a support column, a copper adapter and a shielding layer adapter.

[0019] The power tube is fixed by the upper and lower crimping bases, and the support column is arranged between the upper and lower crimping bases, so that the power tube is tightly connected by the common pressure applied by the support column, thereby forming a multi-stage series high-power switching device.

[0020] The power tube serves as a core device of a power supply and functions as a controllable switch to control the output of the pulse power supply.

[0021] The copper adapter is arranged on the upper crimping base, and a clamping groove structure is designed on the copper disc of the copper adapter to connect the copper core of the upper-end coaxial cable, so that the copper cores of multiple coaxial cables are connected in parallel.

[0022] The shielding layer adapter is arranged above the copper adapter, and the shielding layer of the upper-end coaxial cable is fixed by the threaded clamping groove of the shielding layer adapter, so that the shielding layers of multiple coaxial cables are connected in parallel.

[0023] The support column is also arranged between the shielding layer adapter and the upper crimping base, which not only serves as a support and fixing part of the crimping structure, but also serves as a current return path of the coaxial structure, that is, the current flows from the coaxial cable to the power tube and then returns to the coaxial cable through the support column.

[0024] The power tube is also connected to an RC buffer module, and the RC buffer module is used to reduce the reverse recovery power, so that the peak value of the off voltage and current is inhibited by the RC buffer module after the switch is turned off, thereby avoiding damage of the power tube caused by excessive reverse power.

[0025] The RC buffer module is connected to a control unit, and a trigger signal is output by the control unit to control the conduction of the power tube.

[0026] In the specific implementation, the parameter design of each element in the coaxial valve group structure needs to meet the following conditions:

[0027] For the coaxial structure, the inductance value of the coaxial structure is derived by an electromagnetic theory calculation formula, and the calculation formula is as follows:

[0028]

[0029] Wherein, R is the length from the center of the inner cylinder of the power tube to the center of the outer cylinder (i.e. the support column around the power tube); p is the radius of the inner cylinder; p is the radius of the outer cylinder; and m is the number of outer cylinders.

[0030] The formula for calculating the conductor cross-section of a coaxial cable is as follows:

[0031]

[0032] Where S is the cross-sectional area of ​​the power supply conductor; ρ is the resistivity; Σli is the sum of the product of the current flowing through the line and the length of the coaxial cable conductor; ΔU is the allowable voltage drop of the conductor;

[0033] Based on the insulation model of concentric cylindrical capacitors, as a limiting criterion, all designs must meet the minimum insulation requirements. The distance d between conductors, i.e., the distance between the power transistor and the outer support column, is calculated using the following formula:

[0034]

[0035] In the formula, U is the voltage across the coaxial structure, i.e., the maximum voltage between the power transistor and the external support column; τ is the charge per unit length of the electrode, c / m; ε0 is the dielectric constant in vacuum; ε r is the relative permittivity of the cylindrical homogeneous medium;

[0036] The constraints for optimizing the objective function L(R,l,m) are as follows:

[0037]

[0038] Where R, l, and m are the dimensional parameters of the coaxial structure; L min S represents the minimum inductance value of the coaxial structure under optimal dimensional parameters. min The minimum cross-sectional area of ​​the conductor that can be obtained under the current level of the application scenario; d min This is the minimum spacing between conductors;

[0039] The optimal parameters are calculated based on the voltage and current levels corresponding to the application scenario, and the parameters of each component are designed according to the constraints.

[0040] 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.

[0041] The following comparison uses specific examples. Finite element analysis was performed on both the non-coaxial structure and the coaxial structure of this application, using the same number and type of switching transistors. The inductance values ​​of the two models were calculated at different frequencies, and the results are shown in Table 1 below.

[0042] Table 1 Comparison of Model Inductance Values

[0043] Frequency (Hz) Non-coaxial structure (nH) Coaxial structure (nH) 50k 94.724 44.629 100k 94.424 44.265 500k 94.023 43.78 1G 93.699 43.387

[0044] Comparing the inductance values ​​of coaxial and non-coaxial structures at different frequencies in Table 1, it can be seen that the coaxial structure can effectively reduce the inductance parameters of the valve assembly structure.

[0045] In summary, the super low inductance coaxial valve group structure of the embodiment of the application, on the basis of non-coaxial valve group structure design, uses the support column and the valve group power tube part to form a coaxial structure, optimizes the stray inductance of the power tube crimping part in the valve group, greatly improves the performance of the pulse power supply; and the design of the coaxial structure fully utilizes the conditions of the crimping structure itself without introducing additional parts.

[0046] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is merely intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known by those skilled in the art.

Claims

1. An ultra-low inductance coaxial valve block structure, characterized by, The coaxial valve group structure comprises, from bottom to top, a crimping base, a power tube, a support column, a copper adapter, and a shielding layer adapter. The power tube is fixed by the upper and lower crimping bases, and a support column is arranged between the upper and lower crimping bases. The power tube is tightly connected by the common pressure applied by the support column, thereby forming a multi-stage series high-power switching device. The power tube, as the core device of the power supply, functions as a controllable switch to control the output of the pulse power supply. The copper adapter is installed on the upper crimping base. The copper disc of the copper adapter is designed with a clamping groove structure for connecting the copper core of the upper end coaxial cable, and the copper cores of multiple coaxial cables can be connected in parallel. The shielding layer adapter is installed above the copper adapter. The shielding layer adapter is fixed to the shielding layer of the upper end coaxial cable through the threaded clamping groove of the shielding layer adapter, and the shielding layers of multiple coaxial cables can be connected in parallel. A support column is also installed between the shielding layer adapter and the upper crimping base. The support column not only serves as a support and fixing part of the crimping structure, but also serves as a current return path of the coaxial structure, i.e., the current flows from the coaxial cable to the power tube and then returns to the coaxial cable through the support column. The power tube is also connected to an RC buffer module. The RC buffer module is used to reduce the reverse recovery power. When the switch is turned off, the RC buffer module suppresses the peak voltage and current, thereby avoiding damage to the power tube due to excessive reverse power. The RC buffer module is connected to a control unit. The control unit outputs a trigger signal to control the conduction of the power tube. The parameter design of each element in the coaxial valve group structure needs to meet the following conditions: For the coaxial structure, the inductance value calculation formula of the coaxial structure is derived from the electromagnetic theory calculation formula as follows: Where R is the length from the center of the inner cylinder to the center of the outer cylinder, p is the radius of the inner cylinder, p is the radius of the outer cylinder, and m is the number of outer cylinders. The cross-sectional area calculation formula of the coaxial cable conductor is as follows: Where S is the cross-sectional area of the power supply conductor, p is the resistance coefficient, Σli is the sum of the product of the line current and the length of the coaxial cable conductor, and ΔU is the allowable voltage drop of the conductor. According to the concentric cylinder capacitor insulation model, as a limiting criterion, all designs need to meet the minimum insulation requirement. The distance d between conductors, i.e., the distance between the power tube and the peripheral support column, is calculated as follows: In the formula, U is the voltage borne by the coaxial structure, i.e. the maximum voltage between the power tube and the peripheral support column; τ is the charge amount per unit length of the electrode, c / m; ε0 is the dielectric coefficient in vacuum; ε is the relative dielectric coefficient of the cylindrical homogeneous medium r ; and d is the diameter of the power tube. The constraint condition of the optimization objective function L(R, l, m) is as follows: Wherein, R, l, m are coaxial structure dimension parameters; L min is the minimum inductance value of the coaxial structure under the optimal dimension parameters; S min is the minimum cross section of the wire under the current level of the application scenario; d min is the minimum distance between conductors; The optimal parameters are calculated according to the voltage and current levels of the corresponding application scenarios, and the parameter design of each element is performed according to the constraint condition.

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