A cage fractional turns ratio transformer for high power unipolar pulse modulators

Abstract

The application discloses a cage type fractional turns ratio transformer for a high-power unipolar pulse modulator, and belongs to the technical fields of high-voltage pulse power, power electronic conversion and pulse transformer. The transformer comprises a plurality of independent sub-cores arranged at intervals in a circumferential direction, independent primary winding groups respectively arranged on main magnetic columns of the independent sub-cores, an insulating winding barrel arranged outside a segmented columnar structure formed by all the main magnetic columns, a common secondary winding group wound outside a periphery of the insulating winding barrel, and a demagnetizing winding group. The independent primary winding groups are used for forming main magnetic fluxes of the independent sub-cores, the common secondary winding group is used for coupling the main magnetic fluxes of the independent sub-cores and forming high-voltage pulse output, and the demagnetizing winding group is used for realizing magnetic reset in adjacent pulse intervals. The structure not only compresses the winding length of the common secondary winding group, but also overcomes the end effect problem of a traditional fractional turns ratio transformer, and improves the balance of the independent primary input currents and the consistency of the magnetic flux densities of the sub-cores.

Description

Technical Field

[0001] This invention relates to the fields of high-voltage pulse power, power electronic conversion, and pulse transformer technology, specifically to a cage-type fractional turns ratio transformer for a high-power unipolar pulse modulator. Background Technology

[0002] High-power unipolar pulse modulators are widely used in high-power microwave sources, particle accelerators, and other pulsed power systems. They typically need to generate high-voltage pulses ranging from tens to hundreds of kilovolts within microseconds, and feature high peak current, high repetition frequency, and high output stability. As a key energy transmission component in the pulse modulator, the pulse transformer's magnetic properties, insulation performance, and dynamic response characteristics directly affect the amplitude, rise time, and flat-top stability of the system's output pulse.

[0003] Existing transformer-type pulse modulators mainly include single-core step-up transformers, linear transformer drivers, and fractional turns ratio transformers. Among these, single-core step-up transformers typically require a large number of secondary turns under high-voltage output conditions, easily introducing significant leakage inductance and inter-turn capacitance, affecting pulse rise time and top flatness. Linear transformer drivers usually achieve voltage synthesis through multiple cascaded 1:1 transformers, but require high module synchronization consistency, and the system structure and control complexity increase with increasing output voltage. In contrast, fractional turns ratio transformers achieve high-voltage synthesis through distributed excitation of multiple primary branches and a common secondary winding, offering advantages such as compact structure, low device voltage stress, and good power expansion capability.

[0004] Existing in-line fractional turns ratio transformers typically consist of multiple U-shaped sub-cores arranged in a straight line, a one-turn primary winding on each sub-core, and a common secondary winding coupled together by the sub-cores. This structure offers advantages such as ease of manufacturing and modular expansion. However, because the multiple sub-cores extend in a straight line, the end sub-cores lack symmetrical compensation from adjacent sub-cores on their outer sides, while the middle sub-cores are affected by both sides. This results in inconsistencies in the spatial magnetic field boundaries, leakage flux loops, distance relationships with the common secondary winding, and winding encirclement angles between the end and middle sub-cores. These inconsistencies cause differences in the equivalent magnetizing inductance, leakage inductance, and coupling coefficient among the sub-cores, leading to uneven current distribution in the multiple primary branches. This causes some sub-cores to experience higher magnetic flux density and local magnetic stress, increasing core losses, localized heating, and the risk of magnetic saturation. Meanwhile, the common secondary winding in the linear arrangement structure needs to be arranged along the linear path of multiple sub-cores. The winding path is relatively long, which may lead to an increase in winding resistance, leakage inductance and distributed capacitance, which is not conducive to improving the pulse leading edge speed, top flatness and overall power density.

[0005] Therefore, how to retain the advantages of distributed excitation and high-voltage synthesis of fractional turns ratio transformers while weakening the end effect caused by linear arrangement, improving the magnetic field balance between each sub-core and the current consistency between each primary side branch, and reducing the length of the common secondary winding and related losses has become a key technical problem in the structural optimization of fractional turns ratio transformers for high-power klystron pulse modulators. Summary of the Invention

[0006] The purpose of this invention is to provide a cage-type fractional turns ratio transformer for high-power unipolar pulse modulators, in order to solve the problems of inconsistent coupling conditions between the independent sub-cores and the common secondary winding, significant end effects, and poor primary branch current balance in existing in-line fractional turns ratio transformers.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A cage-type fractional turns ratio transformer for a high-power unipolar pulse modulator includes multiple independent sub-cores, multiple independent primary windings, two sets of common secondary windings, an insulated winding drum, and two demagnetizing windings. Multiple independent sub-cores are arranged circumferentially around a common axis. Each independent sub-core includes a main magnetic column located on the radially inner side, an auxiliary magnetic column located on the radially outer side, and an iron yoke connecting the main magnetic column and the auxiliary magnetic column. The main magnetic column, the auxiliary magnetic column, and the iron yoke together constitute a closed magnetic circuit of the independent sub-core. The main magnetic columns of multiple independent sub-cores are enclosed circumferentially to form a segmented columnar structure. Multiple independent primary windings are respectively wound on the outer circumferential surface of the corresponding main magnetic column, and the winding direction of each independent primary winding is consistent, which is used to establish the main magnetic flux on the closed magnetic circuit of the corresponding independent sub-core. The insulating winding barrel is a hollow insulating barrel body, coaxially sleeved on the outside of the segmented columnar structure; The two sets of common secondary windings are wound on the outer circumferential surface of the insulated winding drum and arranged symmetrically about the axial center of the insulated winding drum. The two sets of common secondary windings extend from both ends of the insulated winding drum towards the axial center area, and the winding direction is opposite to that of the independent primary windings. The low-potential ends of the two sets of common secondary windings are connected to each other to form a low-voltage lead-out terminal, and the high-potential ends of the two sets of common secondary windings are connected to each other to form a high-voltage lead-out terminal. The two sets of common secondary windings simultaneously couple the main magnetic flux in multiple independent sub-cores and output high-voltage pulses. Two demagnetizing windings are respectively wound on the outside of the two sets of common secondary windings, used to synchronously adjust the magnetic state of all independent sub-cores.

[0008] Furthermore, the multiple independent sub-cores are distributed at equal angles along the circumference, with a circumferential interval between adjacent independent sub-cores, and the main magnetic column of each independent sub-core has the same radial distance from the common axis, so that each main magnetic column has the same radial coupling distance from the common secondary winding.

[0009] Furthermore, the yoke includes an upper yoke located at the same end of the main magnetic post and the auxiliary magnetic post along their axial direction, and a lower yoke located at the other end of the main magnetic post and the auxiliary magnetic post along their axial direction. The upper yoke and the lower yoke are radially connected to the main magnetic post and the auxiliary magnetic post, and both the upper yoke and the lower yoke cover the end regions of the main magnetic post and the auxiliary magnetic post.

[0010] Furthermore, the cross-section of the main magnetic column is fan-shaped or isosceles triangle, and multiple main magnetic columns are assembled circumferentially to form a segmented cylindrical or segmented polygonal column structure.

[0011] Furthermore, the insulating winding barrel is a hollow insulating barrel structure with an outer contour that varies along the axial direction; the hollow cross section of the insulating winding barrel is consistent with the outer contour of the segmented columnar structure formed by multiple main magnetic pillars, and there is a preset radial gap between the inner wall of the insulating winding barrel and each main magnetic pillar.

[0012] Furthermore, the low-potential leads of the two sets of common secondary windings are respectively led out from both ends of the insulated winding drum along the axial direction, and the high-potential leads of the two sets of common secondary windings are led out from the central region of the insulated winding drum along the axial direction.

[0013] Furthermore, the wall thickness of the insulating winding drum gradually increases from both ends towards the axial center region along the axial direction, and the wall thickness is symmetrically distributed about the axial center plane of the insulating winding drum.

[0014] Furthermore, the two demagnetizing windings are arranged radially outside the low-potential end of the common secondary winding and symmetrically about the axial center of the insulated winding drum. The demagnetizing windings are used to connect to an external demagnetizing circuit to achieve magnetic state adjustment of the independent sub-core between adjacent pulses.

[0015] Furthermore, insulating retaining walls extending outward in the circumferential direction are respectively provided at both ends of the insulating winding drum. The insulating retaining walls are used to axially limit the common secondary winding and demagnetizing winding wound around the outer circumference of the insulating winding drum.

[0016] Furthermore, the independent sub-core is made of a soft magnetic material, including oriented silicon steel, amorphous alloy, or ferrite material.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention adopts a cage structure in which multiple independent sub-cores are arranged circumferentially around a common axis. Compared with the traditional straight-line arrangement, each independent sub-core has a more consistent spatial position and magnetic circuit environment, which can reduce the magnetic flux deviation caused by end effect and structural asymmetry and improve the magnetic field balance of the multi-core system.

[0018] (2) The present invention forms a segmented columnar structure by enclosing multiple main magnetic columns along the circumference, and coaxially sleeves the common secondary winding on the outside of the segmented columnar structure, so that each independent sub-core and the common secondary winding have an approximately consistent radial coupling distance, which is beneficial to improving the magnetic coupling consistency between each magnetic circuit unit.

[0019] (3) In this invention, multiple independent primary windings are set up to correspond to independent sub-cores and are synchronously excited with the same winding direction, so that each primary branch has consistent magnetic circuit and electromagnetic parameter characteristics, thereby reducing the current imbalance between branches and improving the dynamic current sharing capability when multiple branches are connected in parallel.

[0020] (4) The present invention adopts a common secondary winding structure arranged around the central magnetic circuit region. Compared with the traditional in-line cross-connected winding structure, it can shorten the effective length of the secondary winding, reduce the winding resistance, leakage inductance and parasitic parameters, which is beneficial to improving the dynamic response characteristics in the high voltage pulse transmission process.

[0021] (5) The present invention supports the common secondary winding by means of an insulated winding barrel, and adopts two sets of common secondary windings arranged axially symmetrically and the outer layer arrangement structure of the demagnetizing winding to achieve spatial separation of high and low potential areas, improve the insulation distance between windings and the uniformity of electric field distribution, and reduce the risk of local electric field concentration and partial discharge.

[0022] (6) By setting up an independent demagnetizing winding, the present invention can apply an adjustable magnetomotive force to each independent sub-core between adjacent pulses, realize active reset of the magnetic state, reduce the influence of residual magnetism difference on subsequent pulse excitation process, and improve the output stability under unipolar pulse repetitive operation conditions.

[0023] (7) The present invention adopts a cage-type circumferential distribution structure, which improves the magnetic flux consistency and structural stability of the multi-core system while meeting the requirements of high turns ratio, high power density and high reliability operation of fractional turns ratio transformers. It is suitable for high-power, high-voltage pulse modulators and other high-power pulse energy transmission applications. Attached Figure Description

[0024] Figure 1 This invention provides a schematic diagram of the overall assembly structure of a cage-type fractional turns ratio transformer for a high-power klystron pulse modulator (taking a 4-core design as an example). Figure 2 for Figure 1 The diagram shows a half-section of a cage-type fractional turns ratio transformer. Figure 3 for Figure 1 The diagram shows the core of a cage-type fractional turns ratio transformer. Figure 4 for Figure 1 The diagram shows the installation relationship between the core and coil in a cage-type fractional turns ratio transformer. Figure 5 for Figure 1 A schematic diagram of the coil portion of a cage-type fractional turns ratio transformer is shown. Figure 6 for Figure 1 A simplified schematic diagram of the winding installation process of a cage-type fractional turns ratio transformer is shown. Figure 7 The above is a thermal diagram of the magnetic flux distribution at the central cross-section of the four main magnetic columns under rated operating conditions, as shown in the example. Figure 8 This example illustrates the variation in average magnetic flux density at the central cross-section of the four main magnetic columns under rated operating conditions. Figure 9 This example illustrates the variation in maximum magnetic flux density at the central cross-section of the four main magnetic columns under rated operating conditions.

[0025] Figure 10 This example illustrates the variation of the operating current of the four independent primary windings under rated operating conditions.

[0026] The following is an example of a structural diagram: 1-Core section. 11-Main magnetic column, 12-Auxiliary magnetic column, 13-Upper yoke, 14-Lower yoke; 2-Wire coil section. 21-Insulated winding drum, 22-Independent primary winding, 23-Common secondary winding, 24-Demagnetizing winding. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. For ease of description, a common axis is defined, the direction of extension of the common axis is defined as axial, the direction from the common axis to the outside of each independent sub-core is defined as radial, and the direction around the common axis is defined as circumferential. It should be understood that the following embodiments are only used to illustrate the structural composition, relative positional relationship, assembly method, and an optional parameter design of the present invention, and are not intended to limit the scope of protection of the present invention. Technical features in the various embodiments of the present invention can be combined with each other without conflict.

[0028] like Figure 1 and Figure 2 As shown, the present invention provides a cage-type fractional turns ratio transformer for a high-power unipolar pulse modulator, comprising a core section 1 and a coil section 2. The core section 1 is composed of multiple independent sub-cores, which form multiple circumferentially distributed and mutually independent closed magnetic circuits; the coil section 2 includes multiple independent primary windings, a common secondary winding, and a demagnetizing winding, which are used to respectively realize the excitation of each independent sub-core, the transfer of high-voltage pulse energy, and the adjustment of magnetic state during the pulse interval.

[0029] The core section 1 consists of several structurally identical independent sub-cores arranged circumferentially around a common axis. A predetermined circumferential spacing is provided between each independent sub-core to ensure a basically consistent spatial distribution relative to the common axis. For example... Figure 3 As shown, each independent sub-core includes a main magnetic post 11 positioned near the common axis, an auxiliary magnetic post 12 located radially outside the main magnetic post 11, and a yoke connecting the main magnetic post 11 and the auxiliary magnetic post 12. The yoke includes an upper yoke 13 and a lower yoke 14 respectively positioned at the axial ends of the main magnetic post 11 and the auxiliary magnetic post 12. The upper yoke 13 and lower yoke 14 radially connect the main magnetic post 11 and the auxiliary magnetic post 12, and cover the end regions of the main magnetic post 11 and the auxiliary magnetic post 12. The main magnetic post 11, the auxiliary magnetic post 12, the upper yoke 13, and the lower yoke 14 together constitute a closed magnetic circuit for the independent sub-core. Multiple independent sub-cores form independent magnetic flux paths to achieve independent excitation of the corresponding magnetic circuits of each independent primary winding 22. The independent sub-cores are made of soft magnetic materials, including oriented silicon steel, amorphous alloys, or ferrite materials, preferably oriented silicon steel. When using grain-oriented silicon steel, the appropriate stacking factor can be set according to the material properties and processing requirements, preferably 0.93~0.98. The effective cross-sectional areas of the main magnetic column 11, auxiliary magnetic column 12, upper yoke 13, and lower yoke 14 are determined based on the transformer's rated operating voltage, pulse duration, and the allowable magnetic flux density range of the magnetic material, to meet the volt-second carrying capacity during pulse excitation. The cross-section of the main magnetic column 11 can be configured as a fan shape, an isosceles triangle, or other structural forms suitable for circumferential assembly. Multiple main magnetic columns 11 are arranged circumferentially, with a preset gap between adjacent main magnetic columns 11 to form a segmented columnar structure. The segmented columnar structure can be a segmented cylindrical structure or a segmented polygonal columnar structure, depending on the cross-sectional shape of the main magnetic column 11. Each independent sub-core's main magnetic column 11 has the same radial distance from the common axis, ensuring a consistent spatial positional relationship between the multiple main magnetic columns 11 and the common axis. Multiple auxiliary magnetic columns 12 are located radially outside the corresponding main magnetic column 11, and together with the main magnetic column 11, form a closed magnetic circuit for the corresponding independent sub-core. Each independent sub-core has the same radial spacing between the main magnetic column 11 and the auxiliary magnetic column 12, ensuring a consistent spatial layout of the multiple independent sub-cores relative to the common axis. With the above structure, multiple independent sub-cores are circumferentially enclosed to form a cage-like magnetic core structure. The common secondary winding 23 is arranged around the segmented columnar structure and simultaneously couples the main magnetic flux in multiple independent sub-cores, so that the independent magnetic flux in multiple independent sub-cores can participate in energy transfer together, thereby improving the magnetic coupling consistency between multiple magnetic circuit units.

[0030] The coil section 2 includes an insulated winding drum 21, multiple independent primary windings 22, two sets of common secondary windings 23, and two demagnetizing windings 24, as shown below. Figure 2 and Figure 4 As shown. The independent primary windings 22 are respectively disposed on the outer peripheral surface of the main magnetic column 11 of the corresponding independent sub-core (e.g., Figure 2 , Figure 4 , Figure 5 The orange portion in the image is used to synchronously apply excitation magnetomotive force to each independent sub-core; the two sets of common secondary windings 23 are arranged on the outer periphery of the insulated winding drum 21 (e.g., Figure 2 , Figure 4 , Figure 5 The pink part in the middle is used to simultaneously couple the main magnetic flux generated by multiple independent sub-cores under the action of excitation magnetomotive force and output high voltage pulses; the demagnetizing winding 24 is used to synchronously adjust the magnetic state of each independent sub-core between adjacent pulses.

[0031] The independent primary windings 22 are respectively wound around the outer circumference of the corresponding main magnetic cores 11. Each independent primary winding 22 is arranged with the same winding direction so that each independent sub-core generates a main magnetic flux in the same direction under synchronous excitation conditions. The independent primary windings 22 can adopt a low-turns, large-section conductor structure, and the conductor form and number of turns are determined according to the input pulse voltage, current level, and space size requirements. Multiple independent primary windings 22 can be connected in parallel to an external pulse drive circuit and synchronously apply excitation magnetomotive force to the corresponding independent sub-cores, so that multiple independent sub-cores participate in the pulse energy transfer process together.

[0032] like Figure 5 As shown, the insulated winding barrel 21 is a hollow insulated barrel structure made of insulating material, including nylon, polytetrafluoroethylene (PTFE), epoxy resin, or other insulating media that meet the insulation strength requirements, preferably PTFE. The insulated winding barrel 21 is coaxially sleeved on the outside of the segmented columnar structure formed by multiple main magnetic pillars 11, and located between the independent primary winding 22 and the common secondary winding 23, serving to support the common secondary winding 23 and achieve insulation isolation between the independent primary winding 22 and the common secondary winding 23. The inner contour of the insulated winding barrel 21 is adapted to the outer contour of the segmented columnar structure formed by the multiple main magnetic pillars 11, and its outer circumferential surface is used for winding the common secondary winding 23. Furthermore, the outer contour of the insulated winding barrel 21 can be adjusted according to the winding insulation requirements, and its wall thickness can vary along the axial direction to improve the insulation margin of the primary winding in the high-potential region. The coaxial arrangement of the segmented columnar structure formed by the insulated winding drum 21 and the multiple main magnetic columns 11 ensures that the radial coupling distance between each independent sub-core and the common secondary winding 23 is basically consistent, thereby improving the magnetic coupling consistency between the multiple independent sub-cores and the common secondary winding 23.

[0033] The common secondary winding 23 is wound on the outer circumferential surface of the insulated winding drum 21. Two sets of common secondary windings 23 are symmetrically arranged along the axial direction. Each set of secondary windings extends from both ends of the insulated winding drum 21 towards the axial center, and the two sets of common secondary windings 23 are kept insulated from each other. The common secondary winding 23 can adopt a high-insulation-level conductor structure, and the conductor type, number of turns, and winding spacing are determined according to the output voltage level, load current requirements, and space requirements. Under normal application conditions, the common secondary winding 23 preferably uses a single-strand insulated conductor to meet the requirements of high-voltage insulation and pulse energy transmission. When facing high peak current or special pulse load conditions, the common secondary winding 23 can also adopt a structure of two or more mutually insulated conductors wound in parallel or twisted to improve the secondary current carrying capacity and improve the electromagnetic parameter characteristics of the winding. The common secondary winding 23 is wound in the opposite direction to the independent primary winding 22, so that the common secondary winding 23 can simultaneously couple the main magnetic flux in multiple independent sub-cores and generate a high-voltage pulse at the output terminal of the common secondary winding 23. The low-potential ends of the two sets of common secondary windings 23 are connected to form a low-voltage lead-out terminal, and the high-potential ends of the two sets of common secondary windings 23 are connected to form a high-voltage lead-out terminal. The low-voltage lead-out terminal is used to connect the low-voltage end of the load and the device protective ground, and the high-voltage lead-out terminal is used to connect the high-voltage end of the load, thereby constraining the current flow direction and confirming that the polarity of the voltage applied to the load is correct.

[0034] The two demagnetizing windings 24 are respectively located radially outside the low-potential end of the two common secondary windings 23, and are symmetrically arranged along the axial direction of the insulated winding drum 21 (e.g., Figure 2 , Figure 4 , Figure 5 (The blue portion in the image). The demagnetizing winding 24 maintains a preset insulation distance from the common secondary winding 23 to reduce the electric field influence of the high-potential winding region on the demagnetizing winding 24 and improve overall insulation reliability. The demagnetizing winding 24 can be wound with a low-resistance, high-current-carrying-capacity conductor, and its winding direction can be set according to the required demagnetizing magnetomotive force direction, preferably maintaining the same winding direction as the common secondary winding 23. The number of turns, conductor type, and inter-turn distance of the demagnetizing winding 24 can be determined according to the magnetic reset requirements of the independent sub-cores, the magnitude of the demagnetizing current, and the structural space requirements. Between adjacent pulses, the demagnetizing winding 24 can be connected to an external demagnetizing circuit and apply an adjusting magnetomotive force to each independent sub-core to change the residual magnetic state in the independent sub-cores, restoring it to the preset operating range, thereby reducing the impact of residual magnetism accumulation on magnetic performance during continuous pulse operation.

[0035] The insulating winding drum 21 is provided with insulating retaining walls extending outward in the circumferential direction at both ends of the axial direction. The insulating retaining walls are used to axially limit the common secondary winding 23 and the demagnetizing winding 24 wound on the outer circumference of the insulating winding drum 21, so as to prevent the winding from axially displacing during pulse operation.

[0036] For ease of explanation, Figure 6 A simplified cross-sectional structure of the cage-type fractional turns ratio transformer is shown. Each independent sub-core has an independent primary winding 22 wound around its outer periphery of the main magnetic column 11. The insulated winding drum 21 is coaxially arranged with the common axis and is sleeved on the outside of the segmented columnar structure formed by the multiple main magnetic columns 11.

[0037] In one optional embodiment, two sets of common secondary windings 23 are symmetrically arranged on both sides of the axial direction of the insulated winding drum 21, and are wound from the axial end region to the axial center region of the insulated winding drum 21. The low-potential leads of the two sets of common secondary windings 23 are led out from the axial end regions of the insulated winding drum 21 and connected to each other to form low-voltage leads. The high-potential leads of the two sets of common secondary windings 23 converge and are led out from the axial center region of the insulated winding drum 21 to form high-voltage leads. To improve the insulation reliability of the high-potential region, the axial center region of the insulated winding drum 21 can be configured with a thickened insulation structure, the wall thickness of which gradually increases from the axial end regions to the axial center region, and is symmetrically distributed about the axial center plane of the insulated winding drum 21, thereby increasing the insulation margin near the high-voltage lead region. The demagnetizing winding 24 is located radially outside the common secondary windings 23 and is symmetrically arranged along the axial direction of the insulated winding drum 21. Preferably, the demagnetizing winding 24 is positioned close to both axial ends of the insulated winding drum 21 to maintain a certain spatial distance from the high-voltage lead-out end of the common secondary winding 23. This reduces the electric field coupling between the high-potential winding (common secondary winding 23) and the low-potential winding (demagnetizing winding 24), thereby improving overall insulation performance. Through this structural arrangement, while ensuring that the common secondary winding 23 simultaneously couples the main magnetic flux in multiple independent sub-cores, a reasonable spatial distribution of high and low potential regions is achieved, while also considering the magnetic state adjustment capability and insulation reliability during pulse operation.

[0038] The working principle of the cage-type fractional turns ratio transformer provided by this invention is as follows: During pulse operation, the external pulse drive circuit simultaneously applies an amplitude of [value missing] to multiple independent primary windings 22. Duration is The applied pulse voltage generates an excitation current in each primary winding 22, which, due to its winding around the outer periphery of the main magnetic column 11 of the corresponding independent sub-core, forms a corresponding excitation magnetomotive force and acts on the closed magnetic circuit of each independent sub-core, thereby establishing the main magnetic flux in the corresponding independent sub-core. According to Faraday's law of electromagnetic induction, the magnetic flux corresponding to a single independent sub-core can be expressed as: in, This represents the excitation flux in a single, independent sub-core. This indicates the number of turns in the independent primary winding 22.

[0039] Because the independent primary windings 22 in this invention adopt the same winding direction and are simultaneously excited by a synchronous drive signal, the excitation magnetomotive force in each independent sub-core is in the same direction, resulting in the formation of main magnetic flux with the same direction in multiple independent magnetic circuits. For a cage structure containing multiple independent sub-cores, its total magnetic flux is composed of the main magnetic flux generated by each independent sub-core. in, This represents the total magnetic flux of multiple independent sub-cores. Indicates the number of independent sub-cores. Indicates the first The main magnetic flux in each independent sub-core.

[0040] Because multiple independent sub-cores are arranged circumferentially around a common axis, and the radial distance from each main magnetic column 11 to the common axis is the same, and the multiple main magnetic columns 11 together form a segmented columnar structure, each independent sub-core has essentially the same spatial magnetic circuit conditions. Compared with the traditional in-line magnetic core arrangement structure, this structure reduces the magnetic reluctance variation caused by the spatial position differences of different magnetic circuit units, enabling each independent sub-core to have a more consistent magnetic flux establishment process during synchronous excitation.

[0041] As the main magnetic flux changes with time, the two sets of common secondary windings 23 located on the outer circumference of the insulated winding drum 21 simultaneously link with the main magnetic flux in multiple independent sub-cores, and generate induced voltages according to the law of electromagnetic induction. in, This indicates the output voltage of the common secondary winding 23. This indicates the number of 23 turns in the common secondary winding.

[0042] During the interval between adjacent pulses, to avoid continuous deviation of the operating point of the independent sub-core due to continuous unipolar excitation, the demagnetizing winding 24 can be connected to an external demagnetizing circuit and apply an adjusting magnetomotive force to the independent sub-core. By controlling the demagnetizing current in the demagnetizing winding 24, the residual magnetic flux state in the independent sub-core can be changed, so that each independent sub-core can be restored to the preset magnetic operating range.

[0043] Example 1 This embodiment uses a four-core structure as an example. The four independent cores are evenly distributed circumferentially, and the circumferential spacing angle between two adjacent independent cores is approximately 90°. Each independent core includes a main magnetic post 11 close to the common axis, an auxiliary magnetic post 12 away from the common axis, and an upper yoke 13 and a lower yoke 14 connecting the main magnetic post 11 and the auxiliary magnetic post 12.

[0044] The four main magnetic pillars can adopt an approximate quarter-circle cross-sectional shape, with their paraxial profiles collectively forming the segmented cylindrical outer contour of the central magnetic circuit. The effective cross-sectional area of ​​each of the 11 main magnetic pillars is set to 50.5 cm². 2 The effective cross-sectional area of ​​the auxiliary magnetic post 12, the upper yoke 13, and the lower yoke 14 is set to 51.0 cm². 2 The core material is oriented silicon steel with a thickness of 0.18 mm, and the stacking factor of the core is 0.95.

[0045] Four independent primary windings 22 are wound on their respective main magnetic posts 11. Two sets of common secondary windings 23 are coaxially wound on the outer surface of the insulated winding drum 21, simultaneously surrounding the main magnetic flux regions corresponding to the four main magnetic posts 11 in the circumferential direction. The independent primary windings 22 are made of single-layer thin copper foil with a thickness of 0.3 mm and a width of 400 mm, and their equivalent number of turns is 1 / 4 turn. The common secondary windings 23 are made of copper foil with a cross-sectional area of ​​2 mm². 2 The winding is made of solid round copper wire, with a designed number of 90 turns and an axial turn spacing of 1 mm. Two sets of demagnetizing windings 24 are wound radially outside the two sets of common secondary windings 23, respectively, and use a cross-sectional area of ​​2 mm². 2 Solid round copper wire, each demagnetized winding is wound with 3 turns, and spatially distributed close to the axial ends of the insulated winding drum 21.

[0046] Based on the fractional turns ratio, this transformer can achieve a voltage turns ratio of approximately 1:360.

[0047] Example 2 In a prototype design of a cage-type fractional turns ratio transformer for a klystron load, the target output pulse voltage is 360 kV, the target output pulse current is 320 A, the maximum pulse width is 5 μs, the repetition frequency is 10 Hz to 50 Hz, and the primary excitation voltage is 1 kV. To verify the magnetic flux density distribution of the main magnetic column 11 and auxiliary magnetic column 12 and the current consistency of the independent primary winding 22 under rated volt-second conditions, the primary excitation signal is set to linearly rise from 0 V to 1000 V within 0 to 200 ns in the finite element simulation, and maintain at 1000 V for 0.2 μs to 5.2 μs to simulate the output conditions of an actual chopper circuit. The excitation signal is synchronously applied to the ports of the four independent primary windings 22. The initial simulation state is set to a cold state, that is, no positive magnetic bias is applied to each independent sub-core beforehand.

[0048] After a maximum rated operating time of 5.2 μs, the magnetic flux density distribution of the test sections of the main magnetic column 11 and the auxiliary magnetic column 12 is as follows: Figure 7 As shown. By Figure 7 As can be seen, the magnetic flux distribution in the cross section is relatively uniform, and no significant local hot spots appear. The global maximum magnetic flux density in the simulation area is about 1443 mT, which is lower than the typical saturation knee point of the selected silicon steel material, indicating that the structure has a magnetic saturation margin under rated volt-second conditions.

[0049] To quantify and characterize the magnetic flux consistency among the four main magnetic pillars 11, the ratio of the range of the average magnetic flux density of the four main magnetic pillars 11 at the same time to their average value is used as the average magnetic flux consistency index, and the coefficient of variation is used as an auxiliary evaluation index. The average magnetic flux density of the four main magnetic pillars 11 at the test cross-sections is as follows: Figure 8As shown in the figure, SC1, SC2, SC3, and SC4 represent the four main magnetic pillars 11. Simulation results show that during the pulse leading-out stage, the average magnetic flux density of the four main magnetic pillars 11 test sections differs due to the excitation establishment process and local field distribution; this difference converges rapidly as the magnetic flux gradually builds up. Specifically, at 0.2 μs, the average magnetic flux consistency index is approximately 16.715%, and the coefficient of variation is approximately 6.124%; at 1.0 μs, these values ​​decrease to approximately 5.319% and 2.169%, respectively. After entering the main pulse platform, the average magnetic flux density of the four main magnetic pillars 11 test sections maintains high consistency, and the average magnetic flux consistency index stabilizes within approximately 3% during the period from 2.0 μs to 5.2 μs. At 5.2 μs, the average magnetic flux densities of the four main magnetic cores 11 at the test cross-sections were approximately 1009.143 mT, 978.955 mT, 1003.822 mT, and 1000.933 mT, respectively. Further calculations showed that the range of the average magnetic flux density of the four main magnetic cores 11 at the test cross-sections was approximately 30.188 mT, accounting for approximately 3.024% of the average magnetic flux density, with a coefficient of variation of approximately 1.152%. This indicates that the magnetic flux density deviation among the four independent sub-cores is small, exhibiting good magnetic flux consistency. This demonstrates that the four independent sub-cores possess good magnetic flux accumulation synchronization during the rated pulse plateau.

[0050] The dynamic change of the maximum magnetic flux density at the test section of the main magnetic column 11 is as follows: Figure 9 As shown in the figure, SC1, SC2, SC3, and SC4 represent the four main magnetic pillars 11. The maximum magnetic flux density mainly reflects the local peak magnetic flux and is more susceptible to the influence of edge field distribution, local geometric transition, and pulse leading-edge process compared to the average magnetic flux density. Therefore, during the pulse leading-edge stage, the maximum magnetic flux density dispersion of the test sections of the four main magnetic pillars 11 is relatively high. Using the ratio of the range of the maximum magnetic flux density of the test sections of the four main magnetic pillars 11 at the same time to the average value of the four as the maximum magnetic flux consistency index, the simulation results show that this index gradually decreases from about 71.105% at 0.2 μs to about 7.940% at 5.2 μs, and the corresponding coefficient of variation decreases from about 28.206% to about 3.243%. At 5.2 μs, the maximum magnetic flux densities at the test sections of the four main magnetic pillars 11 were approximately 1391.362 mT, 1287.062 mT, 1330.787 mT, and 1286.247 mT, respectively, all below the typical saturation knee point of the selected silicon steel material. Further calculations showed that the range of the maximum magnetic flux densities at the test sections of the four main magnetic pillars 11 was approximately 105.115 mT, accounting for approximately 7.940% of the average maximum magnetic flux density, with a coefficient of variation of approximately 3.680%. This indicates that during the pulse plateau phase, although the local magnetic flux peak values ​​of each independent sub-core showed some differences due to the influence of the edge field distribution, the overall consistency remained high, and no obvious local magnetic flux concentration phenomenon was observed.

[0051] Furthermore, to simulate actual operating conditions, a typical klystron equivalent load is connected to the common secondary winding 23. This equivalent load is a parallel structure of a resistor and a capacitor, with a resistance of 1125 Ω and a capacitance of 100 pF. Under the same primary-side excitation conditions, the current waveforms of the four independent primary windings 22 are as follows: Figure 10 As shown in the diagram, P1, P2, P3, and P4 represent four independent primary windings 22. Figure 10 It can be seen that the growth trends of the four primary-side currents are basically consistent, all rising rapidly within 0 to 1 μs and then slowly increasing to their peak values ​​between 1 μs and 5.2 μs. The peak values ​​of the four primary-side currents are approximately 30.012 kA, 30.009 kA, 30.027 kA, and 30.035 kA, respectively, with an average peak value of approximately 30.021 kA. The peak value range is approximately 26.4 A, accounting for about 0.087% of the average peak value. This demonstrates that the four independent primary-side windings exhibit good consistency under rated load conditions.

[0052] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A cage-type fractional turns ratio transformer for a high-power unipolar pulse modulator, characterized in that, It includes multiple independent sub-cores, multiple independent primary windings, two sets of common secondary windings, insulated winding drums, and two demagnetizing windings; Multiple independent sub-cores are arranged circumferentially around a common axis. Each independent sub-core includes a main magnetic column located on the radially inner side, an auxiliary magnetic column located on the radially outer side, and an iron yoke connecting the main magnetic column and the auxiliary magnetic column. The main magnetic column, the auxiliary magnetic column, and the iron yoke together constitute a closed magnetic circuit of the independent sub-core. The main magnetic columns of multiple independent sub-cores are enclosed circumferentially to form a segmented columnar structure. Multiple independent primary windings are respectively wound on the outer circumferential surface of the corresponding main magnetic column, and the winding direction of each independent primary winding is consistent, which is used to establish the main magnetic flux on the closed magnetic circuit of the corresponding independent sub-core. The insulating winding barrel is a hollow insulating barrel body, coaxially sleeved on the outside of the segmented columnar structure; The two sets of common secondary windings are wound on the outer circumferential surface of the insulated winding drum and arranged symmetrically about the axial center of the insulated winding drum. The two sets of common secondary windings extend from both ends of the insulated winding drum towards the axial center area, and the winding direction is opposite to that of the independent primary windings. The low-potential ends of the two sets of common secondary windings are connected to each other to form a low-voltage lead-out terminal, and the high-potential ends of the two sets of common secondary windings are connected to each other to form a high-voltage lead-out terminal. The two sets of common secondary windings simultaneously couple the main magnetic flux in multiple independent sub-cores and output high-voltage pulses. Two demagnetizing windings are respectively wound on the outside of the two sets of common secondary windings, used to synchronously adjust the magnetic state of all independent sub-cores.

2. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, Multiple independent sub-cores are distributed at equal angles along the circumference, with circumferential spacing between adjacent independent sub-cores, and the main magnetic column of each independent sub-core has the same radial distance from the common axis, so that each main magnetic column has the same radial coupling distance from the common secondary winding.

3. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, The yoke includes an upper yoke located at the same end of the main magnetic column and the auxiliary magnetic column along the axial direction, and a lower yoke located at the other end of the main magnetic column and the auxiliary magnetic column along the axial direction. The upper yoke and the lower yoke are radially connected to the main magnetic column and the auxiliary magnetic column, and both the upper yoke and the lower yoke cover the end regions of the main magnetic column and the auxiliary magnetic column.

4. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, The cross-section of the main magnetic column is fan-shaped or isosceles triangle, and multiple main magnetic columns are assembled circumferentially to form a segmented cylindrical or segmented polygonal column structure.

5. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, The insulating winding barrel is a hollow insulating barrel structure with an outer contour that varies along the axial direction; the hollow cross section of the insulating winding barrel is consistent with the outer contour of the segmented columnar structure formed by multiple main magnetic pillars, and there is a preset radial gap between the inner wall of the insulating winding barrel and each main magnetic pillar.

6. The cage-type fractional turns ratio transformer according to claim 5, characterized in that, The low-potential leads of the two sets of common secondary windings are respectively led out from both ends of the insulated winding drum along the axial direction, and the high-potential leads of the two sets of common secondary windings are led out from the central region of the insulated winding drum along the axial direction.

7. The cage-type fractional turns ratio transformer according to claim 6, characterized in that, The wall thickness of the insulating winding drum gradually increases from both ends toward the axial center along the axial direction, and the wall thickness is symmetrically distributed about the axial center plane of the insulating winding drum.

8. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, The two demagnetizing windings are located radially outside the low-potential end of the common secondary winding and are arranged symmetrically about the axial center of the insulated winding drum. The demagnetizing windings are used to connect to an external demagnetizing circuit to achieve magnetic state adjustment of the independent sub-core between adjacent pulses.

9. The cage-type fractional turns ratio transformer according to claim 5, characterized in that, The insulating winding drum has insulating retaining walls extending outward in the circumferential direction at both ends of the axial direction. The insulating retaining walls are used to axially limit the common secondary winding and demagnetizing winding wound around the outer circumference of the insulating winding drum.

10. The cage-type fractional turns ratio transformer according to claim 1, characterized in that, The independent sub-core is made of soft magnetic material, including oriented silicon steel, amorphous alloy or ferrite material.

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