JPH03171706A - Pulse transformer - Google Patents

Abstract

PURPOSE: To realize a transformer in which leakage inductance is substantially eliminated by interposing a connecting means between the secondary winding and the core of the transformer in order to connect the core of the transformer with a high voltage thereby minimizing the intermediary matter between the windings and between the winding and the core. CONSTITUTION: A primary winding 8 is made of a foil and clamped to a supporting frame having three parts 10, 11, 12 through linking parts 13, 14, 15. Each part 10, 11, 12 of the supporting frame is made of a conductive material and the part 12 is insulated electrically from the parts 10, 11 through an insulation layer 16. The parts 10, 11 are also connected electrically with a conductive plate 18 through an linking part 17. The circuit for primary current is constituted of the surface of a foil 21 touching the part 12, the body of the part 12, the primary winding 8, the parts 10 and 11, the conductive plate 18, and the surface of the foil 21 touching the conductive plate 18. Since the need of interlayer insulation space is substantially eliminated, the size can be reduced significantly and good results are brought about with regard to joint of leakage inductance.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pulse transformer that converts low voltage pulses into high voltage pulses, and is suitable for connection to a pulse oscillator that generates low voltage pulses. characterized by comprising one primary winding, one secondary winding having high voltage terminals, and one transformer core surrounded at least in part by the primary and secondary windings. It is said that This type of pulse transformer can be used in radar transmitters to generate radar transmission pulses. In that case, this transformer is connected to a pulseformin circuit.
g network) and a high power tube such as a magnetron or talistron.

To be used in this manner, the transformer converts voltage pulses, e.g., hundreds of volts, thousands of amperes, on the order of microseconds in length, generated by a pulse-forming circuit into voltage pulses of tens of kilovolts, tens of amperes. need to be converted to . The thus converted pulses are applied to a talistron or magnetron to generate microwave pulses.

These microwave pulses must be generated repeatedly at a certain period, because the radar receiver uses the gaps between successive pulses to collect the reflected waves of the transmitted pulses. Further, the waveform of the pulse needs to be steep so that the reflected wave can be received immediately after the pulse is sent.

[Conventional technology The steepness of the copulse may be reduced due to what is called the leakage inductance of the pulse transformer. This phenomenon occurs when the degree of coupling between the primary and secondary windings of the transformer is lower than the optimum value. In other words, the electromagnetic fields created by both the primary and secondary windings do not combine sufficiently.

This leakage inductance may be caused not only by the lead wire but also by non-conductive inclusions that insulate the winding and the iron core from each other.

One form of this type of pulse transformer is shown in British Patent Publication No. GB-A2.103.426, which is of the toro-idal type.
A toroidal secondary winding is wound around the core (doughnut-shaped), with the primary completely surrounding the secondary and separated from it by a large amount of insulating material.

[Problems to be Solved] By surrounding the toroidal core with toroidal windings, magnetic flux is mainly confined within the core.

However, one drawback is that a large amount of inclusion is required to insulate the primary and secondary windings from each other, and this insulator can adversely affect the coupling between the two windings.

[Means for Solving the Problem] The purpose of the pulse transformer based on the present invention is to realize a transformer with almost no leakage inductance by minimizing inclusions between the windings and between the windings and the iron core. be. In order to achieve this purpose, this pulse transformer uses a connection means between the secondary winding and the transformer core.
tion means) are provided to connect the high voltage to the transformer core, and the secondary winding is constructed such that at least a portion of its width is surrounded by the entire primary winding.

By doing this, the voltage of the transformer core increases and decreases approximately in line with the voltage of the secondary winding, so that little or no insulation between the secondary winding and the core is required.

As a result, the degree of coupling increases and leakage inductance decreases.

One embodiment of this pulse transformer is characterized in that a primary winding is wound around a secondary winding, which is also shaped by a foil of conductive material, and the secondary winding is also shaped by a conductive foil. Therefore, the potential difference between adjacent layers is small. Therefore, the insulation required between the windings is minimized, which contributes to reducing leakage inductance. In another embodiment to further reduce the leakage inductance, the transformer core is clamped by the primary winding to a conductive support frame, which support frame has one insulating section, 1
The contact surfaces of the latter two are in contact with the conductive sides of the current supply and drain leads of the primary winding, respectively. Therefore, the gap between the primary and secondary windings becomes extremely small and sufficient electrical connection can be obtained.

[Embodiment] A pulse transformer according to the invention can be incorporated into a radar transmission system in a manner as shown diagrammatically in FIG.

A pulse oscillator 2 is connected to the power supply and generates pulses having a length and repetition period suitable for the radar. For this reason, the pulse oscillator 2 includes a circuit network incorporating a delay line, and switching means (swi
tchingmeans), etc., are included. The generated pulses are passed through a fast saturable coil in the usual manner.
il) 3 to the pulse transformer 4. These pulses are blocked by the coil 3 until the switching means inside the pulse oscillator 2 are sufficiently conductive, avoiding power losses due to the switching means themselves.

The pulses applied to pulse transformer 4 have a characteristic pulse length of about 1 microsecond, a characteristic peak voltage of about 400 volts, and a characteristic peak current of about 8000 amperes.

Pulse transformer 4 converts these low voltage pulses into high voltage pulses with a characteristic peak voltage of 80 kilovolts and peak current of 40 amperes. The conversion ratio in this case is therefore 1:200, which value is considerably higher than in a conventional pulse transformer.

This high voltage pulse is then applied to a radar transmitter 5, which transmits a microwave pulse of corresponding pulse length based on the applied pulse from a high power tube such as a magnetron or talistron. Occur.

Finally, these microwave pulses are radiated from the antenna 6.

An embodiment of a pulse transformer according to the invention is shown in FIG. 2, starting with a transformer core 7, a primary winding 8, and a secondary winding 9. The transformer core 7 is made of normal materials and has 2
A magnetic circuit is constructed by joining two U-shaped partial cores without any gaps, and windings 8 and 9 are previously mounted on each opposing partial core before joining. However, the core may be E-shaped with the primary and secondary windings wound around all three legs, or U-shaped with the primary and secondary windings wound around just one leg. Either is fine. The key point is that the primary winding must surround the secondary winding as tightly as possible in order to obtain a suitable degree of coupling.

For this purpose, the primary winding 8, in this case made of foil, is clamped from the three parts 10, 11, 12 via connections 13, 14, 15 to a certain support frame. Support frame 10, 11, 1
Each part of 2 is made of a conductive material, of which part 12 is made of a conductive material.
It is electrically insulated from portions 10 and 11 by an insulating layer l6. The section 12 is in electrical contact with a part of the conductive side of the primary winding 8 , and this section is clamped by the articulation 14 . There is no insulating layer on the side surface of the primary winding 8 adjacent to the transformer core 7. The parts 10 and 11 are electrically connected to the leads of the primary winding 8 which are clamped to them by articulations 13 and 15, respectively. The parts IO and 11 are further connected to a conductive plate via a connecting part 17.
plate) 1B. Portion 12 protrudes from an opening in conductive plate 18 and is clamped to the opposite side of 18 via articulations 19 and 20. A foil 21 is inserted between the portion l2 and the conductive plate 18, and this foil is separated from two conductive surfaces sandwiching an insulating layer. This foil 2l is a saturable coil (s
It is connected to the pulse oscillator 2 via a turable coil 3. The primary current circuit therefore consists of the portion 12
the surface of the foil 21 in contact with the body of the section 12, the primary winding 8,
It consists of parts 10 and 11, a conductive plate 18, and the side of the foil 2l that is in contact with the conductive plate 18. Furthermore, the conductive plate 18
The coil 3 is present between the portion 12 and the portion 12.

Preferably, the primary winding 8 is constructed from a single sheet of foil whose l side is a conductive layer. This is because there is an advantage in that the potential difference between the eyebrows is always kept below 400 volts per layer in this case. As a result, little glabellar insulation space is required, the device can be extremely compact, and leakage inductances are associated with good results. A low voltage lead 22 and a high voltage lead 23 are provided at a portion of the secondary winding 9 closest to the primary winding 8 and a portion closest to the iron core 7, respectively, to enable external connection. High voltage lead 23 is electrically connected to transformer core 7 via a clamp ring 24 surrounding the core. The secondary winding 9 is wound on a coil former (not shown) and freely surrounds the core 7. One of the high voltage leads 23 is connected to the iron core 7 by a capacitor 25.
This capacitor exhibits a low impedance to the generated pulses, and conversely, when connected to a high-power tube, the low-frequency alternating current that is normally passed through the secondary winding heats the filament. It exhibits high impedance to voltage.

It should be noted that there are various methods for electrically connecting the iron core 7 and the secondary winding. As one example, a part of the secondary winding may be wound directly onto the iron core 7, without using a coil shaper as in the above example.

Another example is the use of wire in the secondary winding.
It is also possible to adopt a form using , but the drawback in this case is the increase in insulation space.

FIG. 3 is a side view of this pulse transformer viewed from the direction AA in FIG. 2. The low voltage lead 22 is placed as far away from the transformer core 7 as possible. Width of primary winding 8 and secondary winding 9
The ratio of the widths of , to a large extent, determines the characteristics of the transformer. If anything, better results can be obtained by making the width of the secondary winding wider than that of the primary winding.

[Brief explanation of the drawing]

FIG. 1 shows part of the configuration of a radar transmitter with a pulse transformer. FIG. 2 is an illustration of an embodiment of a pulse transformer with support frame. Figure 3 shows a side view of the winding and iron core of the pulse transformer shown in Figure 2, viewed from the AA direction. 1...Power source 2...Pulse oscillator 3...Fast saturable coil 4...Pulse transformer 5...Radar transmitter 6...Antenna 7...Transformer core 8...Primary Winding 9...Secondary winding 10, 11. 12...Support frame 13, 14
．． 15. 1? ．． 19. 20...Connection part l6.
... Insulating layer l8 ... Conductive plate 21 ... Foil 22 ... Low voltage lead 23 ... High voltage lead 24 ... Clamp ring 25 ... Capacitor

Claims (6)

[Claims] 1. A pulse transformer for converting low-voltage pulses into high-voltage pulses, the transformer having one primary winding suitable for connection to a pulse oscillator for generating low-voltage pulses, and one high-voltage terminal. There is a transformer core surrounded at least in part by secondary windings, primary and secondary windings, and between the secondary winding and the transformer core there is a high voltage Pulse transformer, characterized in that there are connection means for connection to the iron core, and the secondary winding is surrounded at least part of its width by the entire primary winding. 2. 2. The pulse transformer according to claim 1, wherein a flexible conductor is used as the connection means between the transformer core and the high voltage terminal. 3. 2. The pulse transformer according to claim 1, wherein the connection means includes a portion of the secondary winding that is in contact with the transformer core. 4. Pulse transformation according to any one of claims 1, 2 or 3, characterized in that the primary winding in the form of a conductive foil is wound around the secondary winding, also in the form of a conductive foil. vessel. 5. The transformer core includes two U-shaped partial cores that are butt-jointed, and each of the two mutually facing partial cores of the transformer is surrounded by one primary and secondary winding. Any one of claims 1, 2, 3, or 4, wherein the primary and secondary windings of each of the partial cores are connected to the primary and secondary windings of other partial cores, respectively.
Pulse transformer as described in Section. 6. The transformer core is clamped with a primary winding to the conductive part of a support frame, which has an insulating section, a current supply section, and a current drain section, the current supply section and the current drain section being , respectively having contact surfaces with a current supply lead and a current outflow lead of the primary winding.