Tesla transformer with current uniformly distributed in primary coil

Abstract

The invention discloses a Tesla transformer with current uniformly distributed in a primary coil. The Tesla transformer solves the problem that the current distribution at the two ends is not uniform due to the fact that sub-coils in the primary coil of an existing Tesla transformer are equal in length. Comprising an inner magnetic core, a secondary coil, a primary coil and an outer magnetic core which are sequentially and coaxially arranged from inside to outside. The primary coil comprises a first end coil, n-2 middle coils and a second end coil which are coaxially arranged in sequence, n is larger than or equal to 5, and the axial lengths of the multiple middle coils are equal and are all larger than the lengths of the first end coil and the second end coil; the two ends of the first end coil, the two ends of the multiple middle coils and the two ends of the second end coil are all connected with primary leading-out heads, thyristor switches and capacitors are sequentially connected between the corresponding primary leading-out heads at the two ends in series, and a plurality of primary circuits are formed. And finally, the coil current in each primary circuit is uniformly distributed by adjusting and setting the coil length of the end primary circuit.

Description

Technical Field

[0001] The present invention relates to the field of Tesla transformers, and particularly to a Tesla transformer with a uniform current distribution in the primary coil. Background Art

[0002] The sinus series of pulsed sources developed in Russia have the advantages of high repetition frequency, stable performance, and long service life. Its coaxial pulse-forming line incorporates a high-coupling Tesla transformer (including inner and outer open cores and primary and secondary coils). The forming line dielectric usually uses transformer oil, and the forming line serves as the secondary capacitor of the transformer. The open inner core is located outside the inner cylinder of the forming line, and the open outer core is located inside the outer cylinder of the forming line. The lengths of the inner and outer cores are equal and their axial positions are the same; the primary coil is a single-turn cylindrical structure, located inside the outer core and insulated. The primary coil is connected to the peripheral primary circuit through the lead-out rods at its head and tail. The primary coil has multiple lead-out rods, and the primary circuit has multiple thyristor switches and capacitors; the secondary coil is a tapered structure with hundreds or even thousands of turns. The large-end of the secondary coil is connected to the ground of the outer cylinder, and the small-end is electrically connected to the inner cylinder; the axial lengths of the primary and secondary coils are equal. For details, reference can be made to: Document [1] Korovin SD, Rostov VV, Polevin SD, et al. Pulsed power-driven high-power microwave sources [C] / / Proceedings of the IEEE, 2004: 1082-1095; Document [2] Korovin SD, Gubanov VP, Gunin, et al. Repetitive nanosecond high-voltage generator based on spiral forming line [C] / / Pulsed Power Plasma Science, 2001: 1249-1251.

[0003] Since the coupling between the cylindrical primary coil and the tapered secondary coil is weak at both ends, the surface current distribution of the primary coil is unbalanced, and the lead-out currents at both ends of the primary coil are relatively large. The surface current in the middle of the primary coil is basically uniform. Specifically, the coupling on the large-end side of the secondary coil is slightly smaller, and the surface current of the primary coil at the corresponding position is also slightly larger. The current in the primary coil shows a characteristic distribution of large at both ends and relatively uniform in the middle. The primary lead-out current near the large-end of the secondary coil is the largest; the more thyristor switches there are, the larger the current on both sides will be compared to the middle part.

[0004] If the current of the thyristor switch is too large, it will affect its service life and even cause damage. Considering the characteristic that the current at both ends of the primary coil is large, the selection of the thyristor switch usually takes into account meeting the index requirements of the current at both ends of the primary coil. The problem is that the redundancy of the middle thyristor switch will be relatively large. Another consideration for the selection of the thyristor switch is to connect one more thyristor switch in parallel on each side of the primary coil to reduce the current of the thyristor switches on both sides of the primary coil. The problem is that the failure rate of the system increases after the number of core electronic components increases, affecting the long-life reliability of the system.

[0005] It can be seen that, considering the characteristic that the current at both ends of the primary coil of the Tesla transformer is large, to ensure the working safety of the thyristor switch in the primary circuit, usually the performance index of the thyristor is improved or the number of parallel-connected thyristors is increased, resulting in the deficiencies of large thyristor redundancy and increased system failure rate. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem of uneven current distribution at both ends of the primary coil of the existing Tesla transformer, and to provide a Tesla transformer with uniform current distribution in the primary coil.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A Tesla transformer with uniform current distribution in the primary coil, characterized in that it includes an inner magnetic core, a secondary coil, a primary coil, and an outer magnetic core that are coaxially arranged in sequence from inside to outside;

[0009] The primary coil includes a first end coil, n - 2 intermediate coils, and a second end coil that are coaxially arranged in sequence, where n ≥ 5. The axial lengths of the multiple intermediate coils are equal and are all greater than the lengths of the first end coil and the second end coil; both ends of the first end coil, the multiple intermediate coils, and the second end coil are connected with primary leads, and a thyristor switch and a capacitor are sequentially connected in series between the corresponding two ends of the primary leads to form multiple primary circuits;

[0010] The axial length of the first end coil is: l c (1 / n - 0.032)~l c (1 / n - 0.021);

[0011] The axial length of the second end coil is: l c (1 / n - 0.022)~l c (1 / n - 0.016);

[0012] Wherein, l c is the total axial length of the primary coil.

[0013] By axially dividing the primary coil into a plurality of sub-coils, namely the first end coil, n-2 intermediate coils and the second end coil in the present invention, the first end coil, n-2 intermediate coils and the second end coil are respectively connected in series with a capacitor and a thyristor switch to form a primary circuit, and by adjusting and setting the coil length of the end primary circuit, the current distribution of each sub-coil in each primary circuit is made uniform.

[0014] Further, the axial lengths of the primary coil and the secondary coil are equal.

[0015] Further, the secondary coil is a secondary coil with a conical structure, and the first end coil is arranged relative to the end with a larger diameter of the secondary coil, and the second end coil is arranged relative to the other end of the secondary coil.

[0016] Further, the secondary coil is a secondary coil with a single-cone structure.

[0017] Further, the secondary coil is a secondary coil with a double-cone structure.

[0018] Further, insulating gaps are provided between the first end coil and the adjacent intermediate coil, between adjacent intermediate coils, and between the intermediate coil and the second end coil; the length of the insulating gap is 2 mm to 5 mm.

[0019] Further, the axial lengths of the plurality of intermediate coils are equal, and are all greater than the lengths of the first end coil and the second end coil.

[0020] Further, the capacitances of the plurality of capacitors are equal. If the capacitances of the capacitors in the primary circuit are different, it will cause trouble in the customization and backup of the capacitors.

[0021] Further, insulating layers are provided between the first end coil, n-2 intermediate coils, the second end coil and the outer magnetic core.

[0022] Advantages of the present invention:

[0023] The present invention provides a Tesla transformer with uniform current distribution in the primary coil. By reducing the lengths of the sub-coils at both ends of the primary coil and increasing the inductance to reduce the current, the current distribution led out from the primary coil can be made uniform. Description of the drawings

[0024] Figure 1 It is a schematic structural diagram of Embodiment 1 of a Tesla transformer with uniform current distribution in the primary coil of the present invention;

[0025] Figure 2Schematic diagram of the simulation circuit and simulation results when the primary voltage of the primary circuit is 1000V in Embodiment 2 of the Tesla transformer with uniform current distribution in the primary coil of the present invention;

[0026] Among them, (a) represents the simulation circuit diagram; (b) represents the simulation result diagram;

[0027] Figure 3 Schematic diagram of the circuit simulation results when the coils in the primary circuit are of equal length;

[0028] Figure 4 Schematic diagram of the current distribution in two cases where the primary coil is of equal length and variable length;

[0029] Figure 5 Current distributions in two cases where the primary coil has 10 equal-length segments and variable length.

[0030] In the figure, 1 - primary coil; 2 - secondary coil; 3 - outer magnetic core; 4 - inner magnetic core; 5 - primary lead-out head; 6 - thyristor switch; 7 - capacitor. Detailed implementation manners

[0031] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0032] Embodiment 1

[0033] Aiming at the problems of uneven current distribution and easy burnout of each thyristor switch in the Tesla transformer, this embodiment provides a Tesla transformer with uniform current distribution in the primary coil, as Figure 1 shown, including an inner magnetic core 4, a secondary coil 2, a primary coil 1, and an outer magnetic core 3 coaxially arranged in sequence from inside to outside; among them, the axial lengths of the primary coil 1 and the secondary coil 2 are equal.

[0034] The primary coil 1 includes a first end coil, n - 2 intermediate coils, and a second end coil coaxially arranged in sequence, where n≥5, the axial lengths of the multiple intermediate coils are equal, and are all greater than the lengths of the first end coil and the second end coil; in this embodiment, the primary coil is characterized in that the length of the end along the axis is short, and the length of the intermediate coil along the axis is long.

[0035] Considering keeping the capacitance values of each sub-capacitor 7 unchanged, and reducing the current by reducing the lengths of the first end coil and the second end coil at the end of the primary coil 1 and increasing the coil inductance, so as to make the current distribution of each thyristor switch uniform.

[0036] The axial length of the first end coil is: l c (1 / n - 0.032) to l c (1 / n - 0.021);

[0037] The axial length of the second end coil is: l c (1 / n - 0.022) to l c (1 / n - 0.016);

[0038] Among them, l c is the total axial length of the primary coil.

[0039] An insulating layer is provided between the first end coil, n - 2 intermediate coils, the second end coil and the outer magnetic core 3, which can achieve the effect of electrical insulation and protect the coil and the outer magnetic core 3.

[0040] Primary leads 5 are connected to both ends of the first end coil, multiple intermediate coils and the second end coil, and thyristor switches 6 and capacitors 7 are sequentially connected in series between the corresponding primary leads 5 at both ends to form multiple primary circuits. If the capacitance values of the capacitors in the multiple primary circuits are different, it will bring trouble to the customization and backup of the capacitors. In this embodiment, the capacitance values of the multiple capacitors 7 are equal.

[0041] The secondary coil 2 is a conical secondary coil, and the first end coil is arranged at the end with a larger diameter relative to the secondary coil 2, and the second end coil is arranged at the other end relative to the secondary coil 2.

[0042] The secondary coil 2 is a single - cone structure secondary coil or a double - cone structure composed of an outer cone and an inner cone.

[0043] Insulating gaps are provided between the first end coil and the adjacent intermediate coil, between adjacent intermediate coils, and between the intermediate coil and the second end coil; the length of the insulating gap is 2 mm to 5 mm.

[0044] In this embodiment, the primary coil 1 is composed of the first end coil, multiple intermediate coils and the second end coil, and has the characteristics of short ends and long middle; each section of the primary coil is connected in series with the thyristor switch 6 and the capacitor 7 to form an independent primary circuit, and the capacitance values of the capacitors 7 in each primary circuit are equal. The coupling between the two sides of the primary coil 1 and the secondary coil 2 is weak. By increasing the inductance of the two - side coils and reducing the current of the two - side coils, the purpose of equalizing the current of the thyristor switch 6 in each section of the coil is achieved, reducing the maximum current of the thyristor switch 6 and improving the reliability of the use of the thyristor switch 6.

[0045] Embodiment 2

[0046] This embodiment provides a Tesla transformer with a uniformly distributed primary coil current. The oil medium forming line of the built-in Tesla transformer: the axial lengths of the inner core and the outer core are both 1540 mm, the inner diameter of the outer core is 800 mm, and the outer diameter of the inner core is 485 mm; the axial lengths of the primary and secondary coils are both 1200 mm, the number of turns of the secondary coil is 1300, and it is a double-cone structure with a radius of 311 mm at the junction of the inner and outer cones; the primary coil is divided into 5 segments along the axis, and each coil, together with the capacitor and switch outside the core, constitutes an independent primary circuit. The primary circuit of the transformer contains a total of 5 primary circuits; the capacitors of the 5 primary circuits are all 180 μF, the initial voltages are equal, the stray inductance of the primary circuit is 640 nH, and the loss resistance is 25 mΩ; the forming line capacitance, that is, the secondary capacitance, is 0.454 nF; the axial lengths of the primary circuits are 215 mm, 253 mm, 253 mm, 253 mm, and 227 mm in sequence, among which the length of the sub-coil on the side with a larger diameter near the secondary coil is 215 mm.

[0047] Figure 2 Figures (a) and (b) give the simulation circuit and simulation results when the primary voltage is 1000 V. Currents are formed in the primary coil and the secondary coil. Through the magnetic field simulation analysis of the primary and secondary coils, the self-inductance of each coil and the mutual inductance between each other are obtained, and then the coupling coefficient between each coil is calculated. The simulation circuit is as shown in Figure 2 Figure (a). As shown in Figure 2 Figure (b), V(Cp1:2) is the voltage waveform on the primary sub-capacitor Cp1, V(C2:2) is the voltage waveform of the secondary capacitor. At 31 μs, the secondary reaches the maximum voltage of 1.08 MV. I(U1:1), I(U2:1), I(U3:1), I(U4:1), and I(U5:1) are the sub-coil currents, and the maximum values are 6.92 kA, 6.89 kA, 6.94 kA, 6.84 kA, and 6.92 kA respectively. The non-uniformity coefficient of the primary current is: (maximum value - minimum value) / (maximum value + minimum value) = 0.007.

[0048] As a comparative analysis, Figure 3 gives the circuit simulation results when the coils in the primary circuit are of equal length. According to Figure 3 it can be known that the non-uniformity coefficient of the primary current is 0.044. Figure 4 gives the current distributions in two cases where the coils in the primary circuit are of equal length and variable length. The abscissa is the position of the sub-coil, and the ordinate is the normalized value of the primary current. According to Figure 4 it can be known that the effect of equalizing the primary coil current of the present invention is obvious, and the maximum primary current is reduced.

[0049] As Figure 5 shown, it is the current distributions in two cases where the primary coil is divided into 10 segments and is of equal length and variable length. According to Figure 5It can be seen that when designing for primary current homogenization, the length of the coil on the side with a larger diameter near the secondary coil is 86 mm, the length on the other side is 93 mm, and the lengths of the remaining 8 sub-coils in the middle are all 123 mm. The non-uniformity coefficient of the primary current is reduced from 0.066 in the case of equal-length primary coils to 0.014.

[0050] It can be seen from this that a Tesla transformer with a uniform distribution of primary coil current provided by the present invention reduces the current by reducing the lengths of the sub-coils at both ends of the primary coil and increasing the inductance, thereby improving the uniformity of the primary coil current distribution.

[0051] As described above, the above are only the specific embodiments of the present invention and the comparison of the effects of the relevant specific embodiments and related comparative examples. However, the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A Tesla transformer with a uniform distribution of primary coil current, characterized in that, It includes an inner magnetic core (4), a secondary coil (2), a primary coil (1), and an outer magnetic core (3) which are coaxially arranged from inside to outside in sequence; The primary coil (1) includes a first end coil, n - 2 intermediate coils, and a second end coil which are coaxially arranged in sequence, where n ≥ 5. The axial lengths of the multiple intermediate coils are equal and are all greater than the lengths of the first end coil and the second end coil; both ends of the first end coil, the multiple intermediate coils, and the second end coil are connected with primary lead-out heads (5), and thyristor switches (6) and capacitors (7) are sequentially connected in series between the corresponding two ends of the primary lead-out heads (5) to form multiple primary circuits; The axial length of the first end coil is: l c (1 / n - 0.032) to l c (1 / n - 0.021); The axial length of the second end coil is: l c (1 / n - 0.022) to l c (1 / n - 0.016); where l c is the total axial length of the primary coil.

2. The Tesla transformer with uniform distribution of primary coil current according to claim 1, characterized in that: The axial length of the primary coil (1) is equal to that of the secondary coil (2).

3. The Tesla transformer with a uniformly distributed primary coil current according to claim 1, characterized in that: The secondary coil (2) is a secondary coil with a conical structure, and the first end coil is arranged at the end with a larger diameter of the secondary coil (2), and the second end coil is arranged at the other end of the secondary coil (2).

4. The Tesla transformer with a uniformly distributed primary coil current according to claim 3, characterized in that: The secondary coil (2) is a secondary coil with a single-cone structure.

5. The Tesla transformer with a uniformly distributed primary coil current according to claim 3, characterized in that: The secondary coil (2) is a secondary coil with a double-cone structure.

6. The Tesla transformer with uniform distribution of primary coil current according to claim 1, characterized in that: Insulating gaps are provided between the first end coil and the adjacent intermediate coil, between adjacent intermediate coils, and between the intermediate coil and the second end coil; the length of the insulating gap is 2 mm to 5 mm.

7. The Tesla transformer with uniform distribution of primary coil current according to claim 1, wherein: The capacitance values of the multiple capacitors (7) are equal.

8. The Tesla transformer with uniform distribution of primary coil current according to claim 1, characterized in that: Insulating layers are provided between the first end coil, the n - 2 intermediate coils, the second end coil, and the outer magnetic core (3).

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