EP0153808B1 - Transformers - Google Patents
Transformers Download PDFInfo
- Publication number
- EP0153808B1 EP0153808B1 EP85300483A EP85300483A EP0153808B1 EP 0153808 B1 EP0153808 B1 EP 0153808B1 EP 85300483 A EP85300483 A EP 85300483A EP 85300483 A EP85300483 A EP 85300483A EP 0153808 B1 EP0153808 B1 EP 0153808B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- transformer
- saturable reactor
- core material
- pulse
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004804 winding Methods 0.000 claims abstract description 19
- 239000011162 core material Substances 0.000 claims description 16
- 239000004020 conductor Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 description 6
- 238000002592 echocardiography Methods 0.000 description 3
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F17/00—Fixed inductances of the signal type
- H01F17/04—Fixed inductances of the signal type with magnetic core
- H01F17/06—Fixed inductances of the signal type with magnetic core with core substantially closed in itself, e.g. toroid
- H01F17/062—Toroidal core with turns of coil around it
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F19/00—Fixed transformers or mutual inductances of the signal type
- H01F19/04—Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range
- H01F19/08—Transformers having magnetic bias, e.g. for handling pulses
Definitions
- This invention relates to transformers which are particularly suitable for use in pulse circuits in which a high current pulse at relatively low voltage is converted into a very high voltage pulse.
- a transformer of this kind can be used in a pulse circuit to provide the operating power for a high power oscillator, such as a magnetron, which forms part of a radar transmitter.
- a pulse circuit is sometimes termed a radar pulse modulator.
- a radar transmitter can transmit pulses having a very low mark-to-space ratio; that is to say, transmitted short pulses are spaced apart in time by relatively long intervals during which echoes of the pulses are returned by intercepted targets to a radar receiver.
- the useful range of a radar is related to the power transmitted during the short pulse periods and it is therefore very important to maximise the power of these pulses, whilst ensuring that the pulses turn on and off cleanly without the generation of excessive noise.
- the receiver of the radar is enabled so that it can detect weak radar echoes. It is clearly important to ensure that the trailing edges of the transmitted short pulses decay very rapidly and cleanly so that they do not mask echoes received after only a very short delay from targets at close range.
- the present invention seeks to provide an improved transformer which is suitable for use in a pulse circuit.
- a transformer includes a transformer core material shaped to constitute a closed magnetic loop; a toroidal secondary winding wound around said core material so as to magnetically couple therewith; a primary winding part of which comprises a central rigid conductor which is encircled by the core material; characterised by including a saturable reactor core in the form of a hollow cylinder encircling said central rigid conductor and which is also encircled by said core material whereby the primary winding is operative to couple magnetically with the saturable reactor.
- the overall inductance can be kept to a very low value.
- the structures can be physically very large, and the primary currents can also be large, and by combining the transformer function and the saturable reactor function into a physically integrated unit, the overall cost and weight can be reduced whilst the electrical performance is much improved.
- Figure 1 is a simplified circuit diagram illustrating the function of the transformer and saturable reactor
- Figure 2 is a section view showing construction of the transformer incorporating the saturable reactor.
- a high voltage transformer 1 which is adapted to convert a relatively low voltage pulse generated by a pulse forming network 2 into a very high voltage pulse and to make it available at output terminals 3 and 4.
- the pulse forming network 2 consists of a distributed inductive and capacitance circuit as diagrammatically illustrated. Networks of this kind are well known and it is not thought necessary to describe it in further detail.
- the network 2 is periodically charged from a low voltage d.c. power supply present at terminals 5 and 6. When the network is fully charged, the switch 7 is closed thereby permitting the network to rapidly discharge via a saturable reactor 8 and the primary winding 9 of the transformer 1.
- the switch 7 is typically a solid state thyristor it can take a finite time to change from a fully non-conductive state to a fully conductive state, and if appreciable current were allowed to flow through it during this impedance transition phase a great deal of power would be dissipated within the switch itself. It is to prevent this happening that the saturable reactor 8 is provided. As is well known, a saturable reactor initially behaves as an inductance and therefore controls the rate at which the build-up of discharge current can occur, but the magnetic core of the saturable reactor rapidly saturates and then behaves as a very low value inductance, and exhibits a very low impedance.
- the power handling capacity of the transformer is very large.
- the pulse forming network can take a relatively long time to become fully charged, and therefore to store a predetermined amount of energy, its discharge will occur extremely rapidly so that the peak power transferred by the transformer is correspondingly great.
- the primary winding 9 of the transformer 1 is only a single turn although in practice it may consist of two or more turns.
- the secondary winding 20 has a very large number of turns to provide the required step-up voltage.
- output terminal 3 is connected to a high frequency oscillator such as a magnetron, which generates bursts of oscillations during the time that the high voltage pulses are applied to it.
- FIG. 2 there is shown in more detail the pulse transformer which incorporates the saturable reactor as an integral part of it.
- This figure shows a section view taken through the central axis of the transformer.
- the low voltage high current discharge path is represented by the opposite conductive faces 10 and 11 of a double- sided printed circuit board 12.
- This board 12 is held in contact with the housing of the transformer 1.
- the primary winding of the transformer consists of those portions of the conductive sheets 10 and 11 which are adjacent to the transformer, a solid conductive central boss 13, a stud 24 which connects the sheet 10 to the boss 13, a conductive plate 14, and a plurality of conductive studs 15 arranged on a circle around the central boss 13 which make contact with the plate 14 and the sheet 11.
- the central portion of the sheet 11 is removed, so as not to contact the boss 13.
- the studs 15 may be replaced by a cylindrical shell which serves the same electrical function, but this is less satisfactory.
- the secondary winding 20 of the transformer consists of very many turns of fine wire wrapped around a transformer core material 21 which is in the form of a circular ring so that the winding 20 is of a conventional toroidal nature.
- the core material will be mounted in a manner described in our previous UK patent application 8124320, as it is of a relatively delicate mechanical nature.
- the secondary winding 20 is retained in position by embedding it in a non-conductive resin material 16.
- the magnetic core of the saturable reactor 8 is constituted by a thin sleeve 17 of a saturable reactor material which closely surrounds the central boss 13. It will be appreciated that it is entirely surrounded by current flowing in the primary winding in the same way that the core material 21 of the transformer is surrounded. It therefore behaves as a saturable reactor in exactly the same way as the conventional series representation shown in Figure 1.
- an internal metal cylinder 18 is provided in contact with the resin material 16, but spaced apart from the sleeve 17. Heat can therefore be extracted via the plate 14 which can be suitably coupled to an external heat sink system.
- the location of the saturable reactor material in the form of the sleeve 17 makes it unnecessary to provide an additional winding of the kind usually associated with a saturable reactor.
- This enables the inductance of the saturable reactor to be kept at an extremely low level, so that the pulse from the pulse forming network is not distorted to any significant extent.
- the total stray inductance of the transformer and reactor can be altered by changing the profile of the central boss 13.
- an annular recess 22 is formed in its outer surface and this has the effect of increasing the inductance as compared with an unrecessed boss of the same maximum diameter. It is not necessary that the length of the saturable reactor material sleeve 17 is less than the nominal thickness of the transformer housing, as it can project from one or both side faces thereof, if it is necessary to accommodate a large volume of the reactor material.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Multimedia (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Coils Of Transformers For General Uses (AREA)
- Coils Or Transformers For Communication (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
- Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
- Graft Or Block Polymers (AREA)
- Lasers (AREA)
- Generation Of Surge Voltage And Current (AREA)
Abstract
Description
- This invention relates to transformers which are particularly suitable for use in pulse circuits in which a high current pulse at relatively low voltage is converted into a very high voltage pulse.
- A transformer of this kind can be used in a pulse circuit to provide the operating power for a high power oscillator, such as a magnetron, which forms part of a radar transmitter. Such a pulse circuit is sometimes termed a radar pulse modulator. A radar transmitter can transmit pulses having a very low mark-to-space ratio; that is to say, transmitted short pulses are spaced apart in time by relatively long intervals during which echoes of the pulses are returned by intercepted targets to a radar receiver. The useful range of a radar is related to the power transmitted during the short pulse periods and it is therefore very important to maximise the power of these pulses, whilst ensuring that the pulses turn on and off cleanly without the generation of excessive noise. Following the turn off, or decay, of a transmitted short pulse, the receiver of the radar is enabled so that it can detect weak radar echoes. It is clearly important to ensure that the trailing edges of the transmitted short pulses decay very rapidly and cleanly so that they do not mask echoes received after only a very short delay from targets at close range.
- These requirements impose stringent demands on the pulse transformer itself as it may be required to convert an input pulse of only a few hundred volts to an output pulse voltage of up to 30 kV or even higher, whilst handling a peak pulse power of the order of two megawatts.
- The present invention seeks to provide an improved transformer which is suitable for use in a pulse circuit.
- According to one aspect of this invention, a transformer includes a transformer core material shaped to constitute a closed magnetic loop; a toroidal secondary winding wound around said core material so as to magnetically couple therewith; a primary winding part of which comprises a central rigid conductor which is encircled by the core material; characterised by including a saturable reactor core in the form of a hollow cylinder encircling said central rigid conductor and which is also encircled by said core material whereby the primary winding is operative to couple magnetically with the saturable reactor.
- By forming the saturable reactor core within the transformer so that the primary winding also forms part of the saturable reactor, the overall inductance can be kept to a very low value.
- In a high power pulse transformer, the structures can be physically very large, and the primary currents can also be large, and by combining the transformer function and the saturable reactor function into a physically integrated unit, the overall cost and weight can be reduced whilst the electrical performance is much improved.
- The invention is further described by way of example with reference to the accompanying drawings, in which:
- Figure 1 is a simplified circuit diagram illustrating the function of the transformer and saturable reactor,
- Figure 2 is a section view showing construction of the transformer incorporating the saturable reactor.
- Referring to Figure 1 there is shown therein a
high voltage transformer 1 which is adapted to convert a relatively low voltage pulse generated by a pulse forming network 2 into a very high voltage pulse and to make it available at output terminals 3 and 4. The pulse forming network 2 consists of a distributed inductive and capacitance circuit as diagrammatically illustrated. Networks of this kind are well known and it is not thought necessary to describe it in further detail. The network 2 is periodically charged from a low voltage d.c. power supply present at terminals 5 and 6. When the network is fully charged, the switch 7 is closed thereby permitting the network to rapidly discharge via asaturable reactor 8 and the primary winding 9 of thetransformer 1. - As the switch 7 is typically a solid state thyristor it can take a finite time to change from a fully non-conductive state to a fully conductive state, and if appreciable current were allowed to flow through it during this impedance transition phase a great deal of power would be dissipated within the switch itself. It is to prevent this happening that the
saturable reactor 8 is provided. As is well known, a saturable reactor initially behaves as an inductance and therefore controls the rate at which the build-up of discharge current can occur, but the magnetic core of the saturable reactor rapidly saturates and then behaves as a very low value inductance, and exhibits a very low impedance. - Typically, the power handling capacity of the transformer is very large. Although the pulse forming network can take a relatively long time to become fully charged, and therefore to store a predetermined amount of energy, its discharge will occur extremely rapidly so that the peak power transferred by the transformer is correspondingly great. Typically, the primary winding 9 of the
transformer 1 is only a single turn although in practice it may consist of two or more turns. Thesecondary winding 20 has a very large number of turns to provide the required step-up voltage. In order to obtain a rapid discharge of the pulse forming network 2 once the switch 7 has become fully conductive, it is important to minimise the inductance of the discharge path. It has proved very difficult to achieve this in a satisfactory manner. In practice, output terminal 3 is connected to a high frequency oscillator such as a magnetron, which generates bursts of oscillations during the time that the high voltage pulses are applied to it. - Referring to Figure 2, there is shown in more detail the pulse transformer which incorporates the saturable reactor as an integral part of it. This figure shows a section view taken through the central axis of the transformer. The low voltage high current discharge path is represented by the opposite
conductive faces 10 and 11 of a double- sided printedcircuit board 12. Thisboard 12 is held in contact with the housing of thetransformer 1. The primary winding of the transformer consists of those portions of theconductive sheets 10 and 11 which are adjacent to the transformer, a solid conductive central boss 13, astud 24 which connects thesheet 10 to the boss 13, aconductive plate 14, and a plurality ofconductive studs 15 arranged on a circle around the central boss 13 which make contact with theplate 14 and the sheet 11. The central portion of the sheet 11 is removed, so as not to contact the boss 13. Alternatively, thestuds 15 may be replaced by a cylindrical shell which serves the same electrical function, but this is less satisfactory. - The
secondary winding 20 of the transformer consists of very many turns of fine wire wrapped around a transformer core material 21 which is in the form of a circular ring so that the winding 20 is of a conventional toroidal nature. In practice, the core material will be mounted in a manner described in our previous UK patent application 8124320, as it is of a relatively delicate mechanical nature. Thesecondary winding 20 is retained in position by embedding it in anon-conductive resin material 16. - The magnetic core of the
saturable reactor 8 is constituted by athin sleeve 17 of a saturable reactor material which closely surrounds the central boss 13. It will be appreciated that it is entirely surrounded by current flowing in the primary winding in the same way that the core material 21 of the transformer is surrounded. It therefore behaves as a saturable reactor in exactly the same way as the conventional series representation shown in Figure 1. - As the transformer handles very large currents, it inevitably dissipates a certain amount of heat and can become fairly hot in operation. In order to transfer the heat rapidly to a suitable heat sink, an internal metal cylinder 18 is provided in contact with the
resin material 16, but spaced apart from thesleeve 17. Heat can therefore be extracted via theplate 14 which can be suitably coupled to an external heat sink system. - The location of the saturable reactor material in the form of the
sleeve 17 makes it unnecessary to provide an additional winding of the kind usually associated with a saturable reactor. This enables the inductance of the saturable reactor to be kept at an extremely low level, so that the pulse from the pulse forming network is not distorted to any significant extent. The total stray inductance of the transformer and reactor can be altered by changing the profile of the central boss 13. Thus, in Figure 2, anannular recess 22 is formed in its outer surface and this has the effect of increasing the inductance as compared with an unrecessed boss of the same maximum diameter. It is not necessary that the length of the saturablereactor material sleeve 17 is less than the nominal thickness of the transformer housing, as it can project from one or both side faces thereof, if it is necessary to accommodate a large volume of the reactor material.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT85300483T ATE33729T1 (en) | 1984-02-07 | 1985-01-24 | TRANSFORMERS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8403155 | 1984-02-07 | ||
GB08403155A GB2154068B (en) | 1984-02-07 | 1984-02-07 | Transformers |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0153808A1 EP0153808A1 (en) | 1985-09-04 |
EP0153808B1 true EP0153808B1 (en) | 1988-04-20 |
Family
ID=10556185
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85300483A Expired EP0153808B1 (en) | 1984-02-07 | 1985-01-24 | Transformers |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0153808B1 (en) |
AT (1) | ATE33729T1 (en) |
DE (1) | DE3562306D1 (en) |
ES (1) | ES8701423A1 (en) |
GB (1) | GB2154068B (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3546126A1 (en) * | 1985-12-24 | 1987-07-02 | Bosch Gmbh Robert | IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES |
DE20317641U1 (en) * | 2003-11-14 | 2004-01-15 | Vacuumschmelze Gmbh & Co. Kg | Thermal bridge for toroidal inductors |
GB201419162D0 (en) | 2014-10-28 | 2014-12-10 | Rolls Royce Controls & Data Services Ltd | Surface mountable, toroid magnetic device |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2233501C3 (en) * | 1972-07-07 | 1975-01-30 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Arrangement for coupling and decoupling pulses in and out of lines |
US4124822A (en) * | 1977-09-16 | 1978-11-07 | American Optical Corporation | Isolation amplifier |
EP0033441B1 (en) * | 1980-02-01 | 1984-09-12 | Hasler AG | Pulse transformer and its use as isolation transformer |
US4379273A (en) * | 1981-06-25 | 1983-04-05 | Mcdonnell Douglas Corporation | Pulse transformer laser diode package |
-
1984
- 1984-02-07 GB GB08403155A patent/GB2154068B/en not_active Expired
-
1985
- 1985-01-24 DE DE8585300483T patent/DE3562306D1/en not_active Expired
- 1985-01-24 EP EP85300483A patent/EP0153808B1/en not_active Expired
- 1985-01-24 AT AT85300483T patent/ATE33729T1/en not_active IP Right Cessation
- 1985-02-06 ES ES540168A patent/ES8701423A1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
GB2154068B (en) | 1987-07-22 |
ES540168A0 (en) | 1986-11-16 |
ATE33729T1 (en) | 1988-05-15 |
EP0153808A1 (en) | 1985-09-04 |
ES8701423A1 (en) | 1986-11-16 |
DE3562306D1 (en) | 1988-05-26 |
GB2154068A (en) | 1985-08-29 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Melville | The use of saturable reactors as discharge devices for pulse generators | |
US5448580A (en) | Air and water cooled modulator | |
CN1326325C (en) | Power modulator | |
EP0364171B1 (en) | Highfrequency heating apparatus using frequency-converter-type power supply | |
EP3129994A1 (en) | Compact pulse transformer with transmission line embodiment | |
US4612455A (en) | Distributed pulse forming network for magnetic modulator | |
EP0153808B1 (en) | Transformers | |
US3320477A (en) | Power supply having over-voltage and over-current protection means | |
US5138627A (en) | Preionizationd device, in particular for x-ray preionization in discharge-pumped gas lasers, in particular excimer lasers | |
GB1580063A (en) | Modulator for radar transmitters | |
US5412254A (en) | High voltage pulse generator | |
US4496924A (en) | Pulse transformer having conductive shield around magnetic core material | |
GB1085367A (en) | Ignition circuit | |
US6281603B1 (en) | Pulse line generators | |
US4189650A (en) | Isolated trigger pulse generator | |
US5821496A (en) | Method of controlling transient recovery voltage and gas insulation switch gear using the same | |
US4680687A (en) | Switch-mode power supply having a free-running forward converter | |
US4662343A (en) | Method and apparatus for generating high voltage pulses | |
US3792369A (en) | Variable reactance controls for ac powered heating magnetrons | |
GB1584240A (en) | High power variable pulse width triggering circuits | |
US3456221A (en) | High-voltage pulse-generating transformers | |
US6234017B1 (en) | Transducer assembly | |
EP0479357B1 (en) | Power supply device | |
US6329803B1 (en) | Magnetically assisted switch circuit | |
SU1557593A1 (en) | High-voltage pulse transformer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): AT BE CH DE FR IT LI LU NL SE |
|
17P | Request for examination filed |
Effective date: 19850919 |
|
17Q | First examination report despatched |
Effective date: 19861009 |
|
D17Q | First examination report despatched (deleted) | ||
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE CH DE FR IT LI LU NL SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED. Effective date: 19880420 Ref country code: NL Effective date: 19880420 Ref country code: LI Effective date: 19880420 Ref country code: AT Effective date: 19880420 Ref country code: CH Effective date: 19880420 Ref country code: BE Effective date: 19880420 |
|
REF | Corresponds to: |
Ref document number: 33729 Country of ref document: AT Date of ref document: 19880515 Kind code of ref document: T |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Effective date: 19880430 |
|
REF | Corresponds to: |
Ref document number: 3562306 Country of ref document: DE Date of ref document: 19880526 |
|
ET | Fr: translation filed | ||
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
NLV1 | Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 19890131 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Effective date: 19891003 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19891222 Year of fee payment: 6 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19910930 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |