Pulse transformer with both high transformation ratio and fast pulse output capability

Abstract

The present application discloses a pulse transformer that combines high transformation ratio with fast pulse output capability, relating to the technical field of pulse transformers. The transformer comprises an insulating core, a variable impedance wire, and an insulating film wound around the insulating core. The variable impedance wire has a gradually varying width corresponding to the transformation ratio and transmission requirements. The present application has the beneficial effect of gradually varying the variable impedance wire as a conductive layer on the pulse transformer to achieve impedance change. This impedance change causes multiple reflections and transmissions during electromagnetic wave propagation, thereby compressing the pulse width. This allows the pulse transformer to have both high voltage boost capability and fast pulse output capability.

Description

Technical Field

[0001] The present application relates to the technical field of pulse transformers, and in particular to a pulse transformer having both high transformation ratio and fast pulse output capability. Background Art

[0002] A pulse transformer is a transformer specifically designed to generate short, high-voltage pulses. Its core function is to convert fast transient signals (such as square waves or step pulses) from a low-voltage source into high-voltage pulse outputs through magnetic coupling. It plays an important role in high-voltage pulse generation, particularly in applications requiring electrical isolation, high voltage gain, and fast rise times. However, pulse transformers also have significant drawbacks: their high turns ratio results in high internal resistance, limiting their output capability for low-impedance loads. Their voltage-boosting capability is generally positively correlated with their structural parameters: more turns and larger dimensions increase the voltage-boosting capability, but these factors also result in slower output voltage. Consequently, pulse transformers cannot achieve both high voltage-boosting capability and fast pulse output.

[0003] The patent "A High-Voltage Spiral Voltage Multiplier," publication number CN118487490A, publication date July 12, 2024, specifically discloses an outer metal film, an inner metal film, a first insulating film, and a second insulating film. The outer and inner metal films are wound in a spiral bifilar structure, with the first insulating film disposed between the outer and inner metal films, and the second insulating film disposed between the inner and outer metal films. The outer and inner metal films are wound in a spiral bifilar structure to form N turns, with the center positions of any two adjacent turns differing by at least a set offset distance in the axial direction. This solution improves the insulation effect of the spiral transformer by increasing the insulation distance, but there is still the problem of being unable to take into account fast pulse output when high boost capability is required.

[0004] The patent, "Coaxial Helical Reentrant Multi-Voltage Forming Wire," publication number CN106301294A, published on August 19, 2016, specifically discloses three components: an outer forming wire, a helical reentrant inner wire, and a main switch. The helical reentrant wire comprises multiple helical segments with varying pitches. This solution utilizes pitch differences to enable the development of pulse power devices with higher voltages. However, the issue of reduced pulse output efficiency resulting from increased boost capability remains unresolved. Summary of the Invention

[0005] The present application addresses the technical problem in the prior art that pulse transformers cannot take into account both high voltage boosting capability and fast pulse output, and provides a pulse transformer that takes into account both high transformation ratio and fast pulse output capability. The impedance change is achieved by gradually changing the variable impedance line as the conductive layer part on the pulse transformer. The impedance change causes multiple reflections and transmissions in the electromagnetic wave propagation process, thereby achieving pulse width compression, thereby taking into account the fast pulse output capability of the pulse transformer while having high voltage boosting capability.

[0006] In order to achieve the above technical objectives, a technical solution provided by the present application is a pulse transformer that takes into account both high transformation ratio and fast pulse output capability, including: an insulating core, a variable impedance wire and an insulating film wound on the insulating core; wherein the variable impedance wire has a gradual width corresponding to the transformation ratio requirements and transmission requirements.

[0007] Furthermore, the variable impedance line has an exponentially gradual width corresponding to the transformation ratio requirement and the transmission requirement.

[0008] Furthermore, the variable impedance line has a linear gradient width corresponding to the transformation ratio requirement and the transmission requirement.

[0009] Furthermore, one or more sections of the variable impedance line have an exponentially gradient width, and one or more sections of the variable impedance line have a linearly gradient width.

[0010] Furthermore, the outer layer of the insulating inner core is wound with an insulating film, a variable impedance line, an insulating film, and a variable impedance line in sequence from the inside to the outside.

[0011] Furthermore, the decreasing coefficient of the gradient width is calculated according to the boost ratio, the pulse front time and the pulse peaking degree.

[0012] Furthermore, the exponential gradient width ratio and the linear gradient width ratio are comprehensively calculated based on the manufacturing process cost of the exponential gradient width, the manufacturing process cost of the linear gradient width, the pulse front time corresponding to the exponential gradient width, and the pulse front time corresponding to the linear gradient width.

[0013] Furthermore, the variable impedance line is a metal foil with a gradually varying width.

[0014] Furthermore, the variable impedance line is printed on an insulating film.

[0015] Furthermore, the thickness of the variable impedance line is obtained according to the skin effect parameter.

[0016] The beneficial effects of the present application are as follows: the impedance change of the variable impedance line is achieved by gradually changing the width of the variable impedance line, and the impedance change is used to cause multiple reflections and transmissions in the electromagnetic wave propagation process. A complex waveform is formed by superposition of reflected waves and transmitted waves in the transmission line, and the trend of the change in the width of the variable impedance line is calculated according to the transformation ratio requirements and transmission requirements, so that the reflected waves and the transmitted waves interfere with each other at specific positions and times, thereby compressing the pulse width to achieve fast pulse output capability while meeting the high boost multiple requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the gradient width of the pulse transformer that takes into account both high transformation ratio and fast pulse output capability in this application.

[0018] Figure 2 This is a schematic diagram of the structure of a pulse transformer that takes into account both high transformation ratio and fast pulse output capabilities in this application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application more clear, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific implementation method described here is only an optimal embodiment of this application, which is only used to explain this application and does not limit the scope of protection of this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0020] like Figure 1 As shown in the figure, as the first embodiment of the present application, the pulse transformer with both high transformation ratio and fast pulse output capability includes:

[0021] An insulating core, a variable impedance wire, and an insulating film wound around the insulating core;

[0022] The variable impedance line has a gradually changing width corresponding to the transformation ratio requirement and the transmission requirement.

[0023] In this embodiment, a variable impedance line and an insulating film are wound around an insulating core to form a spiral structure, with the insulating film and variable impedance line wound alternately. The insulating film, variable impedance line, insulating film, and variable impedance line are wound around the outer layer of the insulating core in sequence from the inside out. The variable impedance line's gradient width is set based on the pulse transformer's transformation ratio and transmission requirements. This change in the width of the variable impedance line causes the impedance to change along the direction of electromagnetic wave transmission, thereby compensating for waveform variations during the spiral transformer's step-up process.

[0024] Specifically, a spiral transformer typically consists of two alternating layers of metal strips and two insulating layers. The metal layers, often highly conductive copper strips, are primarily used for the transmission and coupling of electromagnetic energy, while the insulating layers provide electrical isolation and electric field control, preventing electrical breakdown or interlayer shorts while carrying high voltage. The core operating mechanism of a spiral transformer is based on the fundamental principle of electromagnetic wave propagation and reflection in a transmission line: When a high-voltage wave is excited at the input, it propagates along a spiral path until it reaches the open-circuit boundary at the end of the spiral. Because the end is not connected to a load, the electromagnetic wave cannot continue its forward motion and is reflected back. The reflected wave propagates in the opposite direction and superimposes with the remaining forward wave along the path, forming the voltage output waveform at the load. However, as the number of turns in the spiral increases, the length of the path along which the electromagnetic wave propagates increases, resulting in an increase in the width of the electrical pulse. To achieve fast pulses and high voltages, the output pulses of the spiral transformer typically require shaping and peaking. However, due to the limitations of insulation properties, these shaping and peaking structures operate at high voltages of hundreds of kilovolts or even millions of kilovolts, making them difficult to miniaturize due to their device parameters.

[0025] In this embodiment, the insulating film is a PP film (polypropylene film), and the variable impedance line is a metal foil with a gradient width. The impedance change of the variable impedance line is achieved by gradually changing the width of the variable impedance line. The impedance change is utilized to cause multiple reflections and transmissions in the electromagnetic wave propagation process. A complex waveform is formed by the superposition of reflected waves and transmitted waves in the transmission line. The trend of the variable impedance line width change is calculated according to the transformation ratio requirements and transmission requirements, so that the reflected wave and the transmitted wave interfere with each other at a specific position and time, thereby compressing the pulse width to achieve fast pulse output capability while meeting the high boost multiple requirements.

[0026] Taking a tape-wound pulse transformer as an example, its inductance per unit length is:

[0027] ;

[0028] Where L represents the inductance per unit length of the winding, Indicates the number of winding turns, represents the vacuum permeability, represents the average radius of the winding, Indicates the winding width.

[0029] Its capacitance per unit length is:

[0030] ;

[0031] Where C is the capacitance per unit length of the winding, Relative dielectric constant, represents the dielectric constant of vacuum, Indicates the thickness of a single insulation layer.

[0032] The pulse transformer with a strip transmission line as its basic structure has a wave impedance determined by the capacitance and inductance per unit length, which is:

[0033] ;

[0034] in, represents the wave impedance of the pulse transformer, It represents the equivalent inductance of the variable impedance line calculated based on the inductance per unit length. It represents the equivalent capacitance of the variable impedance line calculated based on the inductance per unit length.

[0035] When an electrical pulse is transmitted through a variable impedance line, the line redistributes the incident wave energy temporally through the spatially distributed impedance gradient, achieving pulse compression through coherent superposition. Therefore, by setting the width of the variable impedance line with different gradients according to the transformation ratio requirements and transmission requirements, it can adapt to different input pulse shapes and achieve efficient pulse compression. The voltage and current on the variable impedance line satisfy the modified telegraph equation:

[0036] ;

[0037] in, represents the partial derivative of voltage V with time t, represents the equivalent inductance of the variable impedance line at position z, represents the partial derivative of current I with time t, Represents the equivalent capacitance of the variable impedance line at position z.

[0038] During the transmission of electrical pulses, the phase velocity of electromagnetic waves It can be described as:

[0039] ;

[0040] Because the specific values ​​of the equivalent inductance and equivalent capacitance of the variable impedance line vary with position, electromagnetic waves are reflected and refracted during transmission. By gradually decreasing the impedance gradient, the phase velocity of the electric pulse varies at different stages, resulting in significant pulse compression after transmission through the variable impedance line.

[0041] like Figure 2 As shown, the winding composed of variable impedance line and insulation film is connected through the protective resistor and the primary switch To high voltage DC supply voltage When the primary switch is closed, the electric pulse is compressed during the transmission process of the variable impedance line, and at the same time, it reaches the inner open-circuit port from the outer feeding end of the pulse transformer.

[0042] The implementation process of this embodiment is mainly as follows:

[0043] Determine the pulse transformer ratio requirements and transmission requirements;

[0044] The gradient width data of the variable impedance line is calculated based on the transformation ratio requirement, transmission requirement and basic parameters of the pulse transformer;

[0045] Process the variable impedance line and insulating film of corresponding specifications according to the gradient width data;

[0046] The variable impedance line and the insulating film are wound on the insulating core in a pattern of insulating film-variable impedance line-insulating film-variable impedance line to construct a pulse transformer.

[0047] In this embodiment, the transformation ratio requirement includes at least the step-up ratio, the transmission requirement includes at least the pulse leading edge time, the basic parameters of the pulse transformer include at least the primary and secondary electrical parameters and structural parameters, the primary and secondary electrical parameters include at least the turns ratio, inductance and capacitance of the primary and secondary coils, and the structural parameters include at least the structural dimensions of the pulse transformer.

[0048] As the second embodiment of the present application, the difference from the first embodiment is that the variable impedance line has an exponentially gradual width corresponding to the transformation ratio requirement and the transmission requirement.

[0049] When the variable impedance line changes in an exponential manner, its width satisfies:

[0050] ;

[0051] in, Indicates that when the exponential form changes, the length of the spiral expansion is z, and the width of the time-varying impedance line is z. The decreasing coefficient that represents the exponential change, Indicates the initial width of the variable impedance line.

[0052] At this point, an exponentially decreasing coefficient is calculated based on the boost ratio, pulse front time, and pulse peaking. The pulse peaking is calculated based on the degree of distortion experienced by the pulse signal during transmission. The lower the pulse peaking, the better the pulse signal quality and the closer the waveform is to the ideal state. In some cases, the weights for the boost ratio, pulse front time, and pulse peaking can be derived based on historical data on pulse transformer ratios, pulse front time, pulse peaking, and impedance. Alternatively, the weights for each dimension can be derived based on laboratory data and expert experience.

[0053] As the third embodiment of the present application, the difference from the first and second embodiments is that the variable impedance line has a linear gradient width corresponding to the transformation ratio requirement and the transmission requirement.

[0054] When the variable impedance line changes in a linear manner, its width satisfies:

[0055] ;

[0056] in, The length of the spiral expansion when the linear form changes regularly is Time-varying impedance line width, The decreasing coefficient that represents the regular change of linear form, Indicates the initial width of the variable impedance line.

[0057] Similarly, the decreasing coefficient of the linear regular change is calculated based on the boost ratio, the pulse front time and the pulse peaking degree.

[0058] As the fourth embodiment of the present application, it is different from the first, second and third embodiments in that one or more sections of the variable impedance line have an exponentially gradient width, and one or more sections of the variable impedance line have a linearly gradient width.

[0059] Since the exponential gradient width is more difficult to produce in the actual manufacturing process, but the exponential gradient width improves the transmission efficiency more than the linear gradient width, the variable impedance line is designed to have at least one section of exponential gradient width and one section of linear gradient width. The exponential gradient width is used to improve the transmission efficiency, and the linear gradient width compensates for the production cost brought by the exponential gradient width. Through the mutual compensation of the exponential gradient width and the linear gradient width, the pulse transformer can meet a larger range of transmission efficiency requirements while reducing the production difficulty and cost brought by all exponential gradients.

[0060] Specifically, an optimization objective function is constructed according to the manufacturing process cost and the pulse front time. When the transmission efficiency needs to be as high as possible, the exponential gradient width ratio and the linear gradient width ratio are comprehensively calculated according to the manufacturing process cost of the exponential gradient width, the manufacturing process cost of the linear gradient width, the pulse front time corresponding to the exponential gradient width, and the pulse front time corresponding to the linear gradient width, so as to improve the transmission efficiency of the pulse transformer as much as possible within a limited manufacturing process cost.

[0061] This embodiment is different from the first, second and third embodiments in that the variable impedance line is printed on the insulating film.

[0062] In practice, a pulse transformer's conductive layer is preferably thicker to achieve better conductivity. However, the conductivity of printed metal is inferior to that of metal foil, so metal foil is typically used to achieve better conductivity. In this embodiment, an exponentially tapered width is used to balance the conductivity degradation caused by metal printing and compensate for the manufacturing difficulties associated with the exponentially tapered width. This reduces manufacturing difficulty and cost, while improving the transmission efficiency of the pulse transformer.

[0063] At the same time, since the pulse width of the pulse voltage affects the breakdown path of the insulating material, the increase in pulse width can easily lead to insulation failure of the pulse transformer. The present application compensates for the increase in pulse width caused by the voltage boost by gradually changing the width of the variable impedance line, thereby improving the insulation performance of the entire pulse transformer and reducing the possibility of insulation failure. There is no need for an overly thick insulating film, which further reduces the volume of the pulse transformer and improves the insulation reliability of the pulse transformer.

[0064] In this embodiment, the thickness of the variable impedance line is obtained according to the skin effect parameter.

[0065] The skin effect refers to the phenomenon in which alternating current (AC) or an alternating electromagnetic field (EMF) passes through a conductor and the current tends to concentrate in a thin layer on the conductor's surface. Based on the skin effect, the skin depth is calculated based on the pulse frequency, magnetic permeability, and electrical conductivity. The thickness of the variable impedance wire must be greater than or equal to the skin depth to ensure effective current conduction.

[0066] The specific implementation method described above is a preferred implementation method of the pulse transformer of this application that takes into account both high transformation ratio and fast pulse output capability. It does not limit the specific implementation scope of this application. The scope of this application includes but is not limited to this specific implementation method. Any equivalent changes made in accordance with the shape and structure of this application are within the scope of protection of this application.

Claims

1. A pulse transformer with both high transformation ratio and fast pulse output capability, characterized by: include: An insulating core, a variable impedance wire, and an insulating film wound around the insulating core; The variable impedance line has a gradually changing width corresponding to the transformation ratio requirement and the transmission requirement; The impedance changes along the electromagnetic wave transmission direction by changing the width of the variable impedance line. The width of the variable impedance line changes along the length of the spiral expansion to produce an exponential or / and linear regular change.

2. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: The variable impedance line has an exponentially gradual width corresponding to transformation ratio requirements and transmission requirements.

3. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: The variable impedance line has a linearly gradient width corresponding to transformation ratio requirements and transmission requirements.

4. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: One or more sections of the variable impedance line have an exponentially gradient width, and one or more sections of the variable impedance line have a linearly gradient width.

5. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: The outer layer of the insulating inner core is wound with an insulating film, a variable impedance line, an insulating film, and a variable impedance line in sequence from the inside to the outside.

6. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: The decreasing coefficient of the gradient width is calculated according to the boost ratio, pulse leading edge time and pulse peaking degree.

7. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 4, characterized in that: The exponential gradient width ratio and the linear gradient width ratio are comprehensively calculated according to the manufacturing process cost of the exponential gradient width, the manufacturing process cost of the linear gradient width, the pulse front time corresponding to the exponential gradient width, and the pulse front time corresponding to the linear gradient width.

8. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: The variable impedance line is a metal foil with a gradually changing width.

9. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 2 or 4, characterized in that: The variable impedance line is printed on the insulating film.

10. The pulse transformer having both high transformation ratio and fast pulse output capability as claimed in claim 1, characterized in that: Obtain the thickness of the variable impedance line based on the skin effect parameters.

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