GB1564401A - High voltage electrical power supply - Google Patents

High voltage electrical power supply Download PDF

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Publication number
GB1564401A
GB1564401A GB4643275A GB4643275A GB1564401A GB 1564401 A GB1564401 A GB 1564401A GB 4643275 A GB4643275 A GB 4643275A GB 4643275 A GB4643275 A GB 4643275A GB 1564401 A GB1564401 A GB 1564401A
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GB
United Kingdom
Prior art keywords
power supply
cockcroft
capacitors
supply apparatus
electrical
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
Application number
GB4643275A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Atomic Energy Authority
Original Assignee
UK Atomic Energy Authority
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by UK Atomic Energy Authority filed Critical UK Atomic Energy Authority
Priority to GB4643275A priority Critical patent/GB1564401A/en
Publication of GB1564401A publication Critical patent/GB1564401A/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/10—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode arranged for operation in series, e.g. for multiplication of voltage
    • H02M7/103—Containing passive elements (capacitively coupled) which are ordered in cascade on one source
    • H02M7/106—With physical arrangement details

Description

(54) IMPROVEMENTS IN OR RELATING TO HIGH VOLTAGE ELECTRICAL POWER SUPPLY (71) We, UNITED KINGDOM ATOMIC ENERGY AUTHORITY, London, a British Authority, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to high voltage electrical power supply apparatus employing the Cockcroft-Walton circuit. Availability of semi-conductor devices enabling the required high frequency drive for the Cockcroft Walton circuit to be obtained efficiently and conveniently has led to an increasing use of the method for outputs up to tens of kilowatts. A power supply apparatus and one circuit particularly suitable for driving a Cockcroft-Walton circuit is described in British Patent Specification No. 1,297,786.
The apparatus described in that Patent Specification comprises a stack of modular units each manufactured to a standard form.
By varying the number of modules any required output voltage can be realised within the limitations of power output and electrical breakdown strength of the circuit components.
The polarity of the output voltage is determined by the direction of current conduction determined by the rectifier diodes of the circuit, and it is a common practice to obtain reversal of output polarity by inverting, physically, the entire stack assembly, while providing additional switches or relays to reverse such auxiliary circuits as are required for indication, overload protection and control. This method of polarity reversal is cumbersome and becomes increasingly inconvenient as the output powers and voltages are increased.
An object of this invention is to facilitate reversal of the output polarity of a Cockcroft Walton power supply apparatus, particularly such apparatus of the form comprising a stack of modular units.
The invention provides a Cockcroft Walton power supply apparatus comprising a plurality of modular units and electrical interconnections between the said units, each of which modular units comprises rectifier diodes mounted in a disc of supporting material, capacitors mounted in an annulus of supporting material extending around the periphery of the disc, and a plurality of electrical contact making members on the disc and the annulus so connected and located as to permit the electrical interconnection between the rectifier diodes and the capacitors within the modular unit to be adjusted, by relative rotation of the disc and the annulus, between that appropriate for onepolarity of electrical output form the apparatus and that appropriate for the opposite polarity of electrical output from the apparatus.
Preferably, in addition, switching means are actuated by the said relative movement for reversing, where necessary, the auxiliary circuits of the apparatus.
Preferably the disc and annulus comprise the rectifier diodes and the capacitors respectively, embedded in plastics material. If capacitors having a metal casings are employed then, conveneintly, the capacitors are arranged in the annulus in a ring, the metal casings of the capacitors in combination thereby acting as an encompassing screen for the electrical components in the modular unit.
Alternatively if a metal encompassing screen is required this may be provided as a separate component embedded in the annulus. The function of such a screen, which is in use of the power supply apparatus is desirably held at a potential intermediate, preferably mid-way between, that of electrical input and output terminals of the modular unit, is to provide a smoothly curved and large radius outwardly facing surface for meeting stressing requirements between adjacent modular units when mounted in a stack.
By stressing is meant the arrangement and design of the electrical components and terminations so as to avoid electrical breakdown, for example by sparking across a gap between capacitor terminals.
Specific constructions of apparatus embodying the invention will now be described by way of example and with reference to the drawings filed herewith, in which:-- Figures 1 and 2 are electrical circuit diagrams showing respectively the symmetrical and the assymmetrical forms of conventional Cockcroft-Walton power supply apparatus with positive output; Figures 3 and 4 are electrical circuit diagrams of respectively the symmetrical and assymmetrical forms of Cockcroft-Walton power supply apparatus with negative output; Figures 5a and 5b are electrical circuit diagrams of part of a symmetrical form of Cockcroft-Walton power supply appartus embodying the invention; Figures 6a and 6b are electrical circuit diagrams of part of an assymmetrical form of Cockcroft-Walton power supply apparatus embodying the invention; and Figure 7 is a diagrammatic side view partly in section, and with some parts omitted, of a Cockcroft-Walton power supply apparatus embodying the invention.
Inspection of Figures 1 and 3 and Figures 2 and 4 shows the manner in which the interconnections between rectifier diodes and capacitors have to be interchanged to reverse the polarity of the output referenced 10.
Figures 5a and 5b show how the required interchange of connections between the rectifier diodes and the capacitors may be obtained for a symmetrical Cockcroft-Walton circuit by rotating the rectifier assembly through 180 . A,B,C and D represent contacts fixed in space on the main part of stack, and connected to the capacitors. The diodes U are mounted in an assembly that can be rotated and which carries the contacts P, Q, R and S.
Rotation of the diode assembly through 180 from the position shown in Figure 5a results in the interconnection shown in Figure 5b, thus achieving the required polarity reversal as may be seen by checking against Figures 1 and 3.
Figures 6a and 6b show how similar results can be obtained from an assymmetrical circuit using three fixed contacts A', B', C' and four moving contacts P', Q', R', S' on the rectifier diode assembly, two of which are connected together within the assembly.
Figure 7 shows a Cockcroft-Walton power supply apparatus comprising a stack of modular units.
The stack consists of five annular members 12 comprising the capacitors, (not shown) potted in plastics material and mounted off a base plate 13 by means of electrically insu lating bushes 14, and separated from each other by bushes 16. Electrically conducting cables 15 pass through the bushes 14 to carry the high frequency input drive to the stack.
Electrical connections between the annular members 12 are made by contacts (not shown) contained inside the bushes 16.
At the top of the stack, an aluminium spinning 17, supported from the top annular member 12, forms the high voltage terminal from which the output is taken.
Associated with each annular member 12 is an inner disc 18 comprising the rectifier diodes (not shown) potted in a plastics material. The discs 18 are mounted on and keyed to an electrically insulating shaft 19. The shaft is supported by bearings at 21 and 22, and is extended to carry a cam 23 and an operating handle 24.
A projection 25 on the cam co-operates with projections such as 26 to define the limits of the required movement of the shaft necessary to perform the interchange of the connections between the diodes and the capacitors which are made by the spring loaded contacts 27.
The invention is not restricted to the details of the foregoing examples. For instance, if required for meeting the electrical stress conditions, an equipotential ring at or near the periphery of the annulus of each modular unit may be provided. Such an equipotential ring is preferably held at a potential mid-way between that of the input and output terminals of the modular unit. The equipotential ring may be provided by a separate metal ring embedded in or plated onto the plastics material of the annulus. Alternatively, where capacitors with metal outer casings are employed, these capacitors may be located in each plastics material annulus 12 in a ring, with each capacitor in physical and electrical contact with its neighbouring capacitors in the ring. In this way the capacitors casings form an encompassing screen around all the components in the annulus 12 and disc 18 of each modular unit. The encompassing screen is of relatively large effective radius of curature and eases the stressing problems as between one modular unit and adjacent modular units.
It also eases the stressing problems as between one modular unit and any surrounding earthed components, such as the main supporting frame.
WHAT WE CLAIM IS:- 1. A Cockcroft-Walton power supply apparatus comprising a plurality of modular units and electrical interconnections between the said units, each of which modular units comprises rectifier diodes mounted in a disc of supporting material, capacitors mounted in an annulus of supporting material extending around the periphery of the disc, and a plurality of electrical contact making members on the disc and the annulus so connected and located as to permit the electrical interconnection between the rectifier diodes and the capacitors within the modular unit to be adjusted, by relative rotation of the disc and the annulus, between that appropriate for one polarity of electrical output from the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    by way of example and with reference to the drawings filed herewith, in which:-- Figures 1 and 2 are electrical circuit diagrams showing respectively the symmetrical and the assymmetrical forms of conventional Cockcroft-Walton power supply apparatus with positive output; Figures 3 and 4 are electrical circuit diagrams of respectively the symmetrical and assymmetrical forms of Cockcroft-Walton power supply apparatus with negative output; Figures 5a and 5b are electrical circuit diagrams of part of a symmetrical form of Cockcroft-Walton power supply appartus embodying the invention; Figures 6a and 6b are electrical circuit diagrams of part of an assymmetrical form of Cockcroft-Walton power supply apparatus embodying the invention; and Figure 7 is a diagrammatic side view partly in section, and with some parts omitted, of a Cockcroft-Walton power supply apparatus embodying the invention.
    Inspection of Figures 1 and 3 and Figures 2 and 4 shows the manner in which the interconnections between rectifier diodes and capacitors have to be interchanged to reverse the polarity of the output referenced 10.
    Figures 5a and 5b show how the required interchange of connections between the rectifier diodes and the capacitors may be obtained for a symmetrical Cockcroft-Walton circuit by rotating the rectifier assembly through 180 . A,B,C and D represent contacts fixed in space on the main part of stack, and connected to the capacitors. The diodes U are mounted in an assembly that can be rotated and which carries the contacts P, Q, R and S.
    Rotation of the diode assembly through 180 from the position shown in Figure 5a results in the interconnection shown in Figure 5b, thus achieving the required polarity reversal as may be seen by checking against Figures 1 and 3.
    Figures 6a and 6b show how similar results can be obtained from an assymmetrical circuit using three fixed contacts A', B', C' and four moving contacts P', Q', R', S' on the rectifier diode assembly, two of which are connected together within the assembly.
    Figure 7 shows a Cockcroft-Walton power supply apparatus comprising a stack of modular units.
    The stack consists of five annular members
    12 comprising the capacitors, (not shown) potted in plastics material and mounted off a base plate 13 by means of electrically insu lating bushes 14, and separated from each other by bushes 16. Electrically conducting cables 15 pass through the bushes 14 to carry the high frequency input drive to the stack.
    Electrical connections between the annular members 12 are made by contacts (not shown) contained inside the bushes 16.
    At the top of the stack, an aluminium spinning 17, supported from the top annular member 12, forms the high voltage terminal from which the output is taken.
    Associated with each annular member 12 is an inner disc 18 comprising the rectifier diodes (not shown) potted in a plastics material. The discs 18 are mounted on and keyed to an electrically insulating shaft 19. The shaft is supported by bearings at 21 and 22, and is extended to carry a cam 23 and an operating handle 24.
    A projection 25 on the cam co-operates with projections such as 26 to define the limits of the required movement of the shaft necessary to perform the interchange of the connections between the diodes and the capacitors which are made by the spring loaded contacts 27.
    The invention is not restricted to the details of the foregoing examples. For instance, if required for meeting the electrical stress conditions, an equipotential ring at or near the periphery of the annulus of each modular unit may be provided. Such an equipotential ring is preferably held at a potential mid-way between that of the input and output terminals of the modular unit. The equipotential ring may be provided by a separate metal ring embedded in or plated onto the plastics material of the annulus. Alternatively, where capacitors with metal outer casings are employed, these capacitors may be located in each plastics material annulus 12 in a ring, with each capacitor in physical and electrical contact with its neighbouring capacitors in the ring. In this way the capacitors casings form an encompassing screen around all the components in the annulus 12 and disc 18 of each modular unit. The encompassing screen is of relatively large effective radius of curature and eases the stressing problems as between one modular unit and adjacent modular units.
    It also eases the stressing problems as between one modular unit and any surrounding earthed components, such as the main supporting frame.
    WHAT WE CLAIM IS:- 1. A Cockcroft-Walton power supply apparatus comprising a plurality of modular units and electrical interconnections between the said units, each of which modular units comprises rectifier diodes mounted in a disc of supporting material, capacitors mounted in an annulus of supporting material extending around the periphery of the disc, and a plurality of electrical contact making members on the disc and the annulus so connected and located as to permit the electrical interconnection between the rectifier diodes and the capacitors within the modular unit to be adjusted, by relative rotation of the disc and the annulus, between that appropriate for one polarity of electrical output from the
    apparatus and that appropriate for the opposite polarity of electrical output from the apparatus.
  2. 2. A Cockcroft-Walton power supply apparatus as claimed in Claim 1, wherein, in addition, switching means are actuated by the said relative movement for reversing the auxiliary circuits of the apparatus.
  3. 3. A Cockcroft-Walton power supply apparatus as claimed in Claim 1, wherein the said disc and the said annulus comprise the rectifier diodes and the capacitors respectively, embedded in plastics material.
  4. 4. A Cockcroft-Walton power supply apparatus as claimed in Claim 3, wherein the capacitors have metal casings and are arranged in the annulus in a ring, the metal casings of the capacitors in combination thereby acting as an encompassing screen for the electrical components in the modular unit.
  5. 5. A Cockcroft-Walton power supply apparatus as claimed in Claim 3, wherein a metal encompassing screen is provided as a separate component embdded in the annulus.
  6. 6. A Cockcroft-Walton power supply apparatus as claimed in Claim 5, wherein in use of the power supply apparatus the screen is held at an electrical potential intermediate that of electrical input and output terminals of the modular unit.
  7. 7. A Cockcroft-Walton power supply apparatus as claimed in Claim 6, wherein in use of the power supply apparatus the screen is held at an electrical potential mid-way between that of the said input and output terminals of the modular unit.
  8. 8. A Cockcroft-Walton power supply apparatus substantially as hereinbefore described with reference to, and illustrated in, Figures 5a and 5b or Figures 6a and 6b, and Figure 7 of the drawings filed herewith.
GB4643275A 1976-09-29 1976-09-29 High voltage electrical power supply Expired GB1564401A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB4643275A GB1564401A (en) 1976-09-29 1976-09-29 High voltage electrical power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4643275A GB1564401A (en) 1976-09-29 1976-09-29 High voltage electrical power supply

Publications (1)

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GB1564401A true GB1564401A (en) 1980-04-10

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0370302A2 (en) * 1988-11-21 1990-05-30 Siemens Aktiengesellschaft Multistage cascade rectifier
GB2306808A (en) * 1995-10-20 1997-05-07 Eni Inc Strike enhancement circuit for plasma generator
EP0991174A2 (en) * 1998-09-30 2000-04-05 NEC Corporation High-voltage power supply circuit having a plurality of diode bridges connected in series to the secondary winding of a transformer
CN103731045A (en) * 2014-01-17 2014-04-16 中国航空工业集团公司北京航空制造工程研究所 High voltage power supply

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0370302A2 (en) * 1988-11-21 1990-05-30 Siemens Aktiengesellschaft Multistage cascade rectifier
EP0370302A3 (en) * 1988-11-21 1990-10-03 Siemens Aktiengesellschaft Multistage cascade rectifier
GB2306808A (en) * 1995-10-20 1997-05-07 Eni Inc Strike enhancement circuit for plasma generator
US5717293A (en) * 1995-10-20 1998-02-10 Eni Technologies, Inc. Strike enhancement circuit for a plasma generator
EP0991174A2 (en) * 1998-09-30 2000-04-05 NEC Corporation High-voltage power supply circuit having a plurality of diode bridges connected in series to the secondary winding of a transformer
EP0991174A3 (en) * 1998-09-30 2001-04-11 NEC Corporation High-voltage power supply circuit having a plurality of diode bridges connected in series to the secondary winding of a transformer
CN103731045A (en) * 2014-01-17 2014-04-16 中国航空工业集团公司北京航空制造工程研究所 High voltage power supply

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PCNP Patent ceased through non-payment of renewal fee