GB2111326A - No-break power supply - Google Patents

No-break power supply Download PDF

Info

Publication number
GB2111326A
GB2111326A GB08136142A GB8136142A GB2111326A GB 2111326 A GB2111326 A GB 2111326A GB 08136142 A GB08136142 A GB 08136142A GB 8136142 A GB8136142 A GB 8136142A GB 2111326 A GB2111326 A GB 2111326A
Authority
GB
United Kingdom
Prior art keywords
supply
voltage
conditioner
input
supply conditioner
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.)
Granted
Application number
GB08136142A
Other versions
GB2111326B (en
Inventor
Lawrence John Berman
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.)
Chloride Group Ltd
Original Assignee
Chloride Group Ltd
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 Chloride Group Ltd filed Critical Chloride Group Ltd
Priority to GB08136142A priority Critical patent/GB2111326B/en
Publication of GB2111326A publication Critical patent/GB2111326A/en
Application granted granted Critical
Publication of GB2111326B publication Critical patent/GB2111326B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
    • H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
    • 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
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/538—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration
    • H02M7/53803—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration with automatic control of output voltage or current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
    • Y04S20/20—End-user application control systems

Abstract

An A.C. power supply conditioner uses semi-conductor diodes (D1) and (D2) and energy storage capacitors (C1) and (C2) to produce a high D.C. voltage which is inverted at (TR1) and (TR2) to provide an A.C. output (L0, N0) without use of isolating transformer. A standby battery system includes a low voltage battery 'B' a DC/AC/DC converter 'E', and a charger 'F'. The inverter may provide a high frequency square wave, pulse-width modulated to form an effective sine wave at input frequency. In the event of a fault, switch G may be automatically changed-over. <IMAGE>

Description

SPECIFICATION Pawer supply conditioner This invention relates to a power supply conditioner for an AC load which may be susceptible to short term variations, spikes and dips in the supply and indeed short term interruptions in the supply.
One object of the present invention is to provide such a conditioner which is simple and cheap.
According to the present invention, in an A.C.
power supply conditioner, the A.C. input supply is rectified and used to charge energy storage capacitor means at a high D.C. voltage (i.e. a voltage comparable with the A.C. supply voltage), and an A.C. output signal is derived from the high D.C. voltage.
The high D.C. voltage can be derived merely by rectifying the A.C. supply, possibly by use of a voltage doubling arrangement, so that the D.C.
voltage can be the equivalent of twice the peak voltage of the A.C. input supply, and if for example the A.C. output signal is derived from the high D.C. voltage by an inverter using high voltage power transistors the conditioner need not include a transformer so that it can be simple and cheap. The energy storage capacitor means enable the high D.C. voltage to be maintained substantially constant in spite of certain variations in the A.C. input supply.
One side of the AC. input supply can be connected through to the A.C. output supply and can act as a centre point of the high D.C. voltage.
The conditioner is very suitable for use in combination with a battery stand-by system using a low voltage battery, because a DC/AC/DC converter can couple the battery to the high voltage D.C. supply, and the converter can include a step-up isolating transformer which can be a high frequency transformer so as to be small and cheap.
There may be a battery charger for the standby battery which charger is driven from the A.C.
input supply.
There may be a switch arranged to connect the A.C. input supply directly to the A.C. output in response to failure of the supply conditioner, thereby providing an uninterruptable power supply system.
The invention may be carried into practice in various ways, and one embodiment will now be described by way of example, with reference to the accompanying drawings, of which: Figure 1 is a circuit diagram of a power supply; and Figure 2 is a diagram of the switching waveform.
In Figure 1, an A.C. power supply between the terminals 'L' and 'N' is used for energising a load to be connected across the terminals 'leo' and 'N0, which load is to be protected from short term variations, spikes, and dips in the supply, as well as longer term voltage variations and actual interruptions for short periods.
Accordingly, the supply at 'LN' is rectified by a voltage doubler rectifying device comprising semiconductor diodes D, and D2, which voltagedoubled rectified supply appears across a pair of energy storing and filtering capacitors C1 and C2 connected in series. The common point of the capacitors is connected to the neutral of the supply so that the outer ends of the series connected capacitors are respectively at plus DC volts and minus DC volts corresponding to the AC peak voltage.
A pair of transistors TR, and TR2 have their collector/emitter paths connected in series across the DC supply, and the common point is connected through an inductance 'L, to the output terminal LO. The output terminal No is connected to the A.C. supply neutral 'N'.A capacitor C3 is connected across the output terminals LO, No to constitute with the inductance L, a small low-pass filter for removing carrier frequencies derived from a system for switching the transistors TR1 and TR2 alternately at a high carrier frequency to provide an approximately sinusoidal waveform between L0 and N,. The switching sequence will be controlled in accordance with the requirements and the conditions in the mode to produce a squarewave signal at carrier frequency, but with variable mark/space ratio modulation which after filtering at L1, C3 produces an approximation to a sine wave as is shown in Figure 2.
A pair of semi-conductor diodes D3 and D4 connected across the respective transistor collector/emitter paths enable reactive currents from the filter or the load to be fed back to charge the capacitors C, and C2.
If the voltage and/or the current in the load circuit is to be controlled, then voltage and/or current sensitive devices can have their outputs connected to a control circuit which provides the carrier frequency signals for switching the transistors TR and TR2, so that the periods during which they are on can be controlled.
Use of the capacitors C, and C2 for storing energy and preventing rapid changes of voltage across the D.C. circuit terminals, enables the load to be protected from variations and even short interruptions in the A.C. voltage applied to the terminals L and N.
To protect the load from loss of the A.C. supply for a period longer than can be handled by the capacitors C, and C2 and possibly for a period of several hours, a battery back-up system is provided which includes a battery 'B' and a DC/HFAC/DC converter 'E' connected across the D.C. circuit terminals. Such a converter is known in itself, and includes an inverter consisting of semiconductor components to provide a high frequency alternating signal, a high frequency transformer providing isolation and step-up to the voltage of the D.C. circuit, and a rectifier whose output is connected across the D.C. terminals +DCV and -DCV. A small battery charger 'F' supplied from the mains LN is used for keeping the battery 'B' charged at a low rate.
In case the conditioner circuit should fail a bypass switch 'G', is provided which may be mechanical electromechanical, or semiconductor static, and which can act automatically to connect the supply terminal 'L' directly to the output terminals L0 in the event of conditioner circuit failure. Thus an uninterruptable power supply is ensured.
It will be appreciated that the conditioner circuit is very simple, and includes no moving parts, apart from the switch 'G' if that is not a semiconductor switch, and can be quite compact in particular because the transformer in the converter 'E' can be a small high frequency transformer.
The battery 'B' is a low voltage battery.
Moreover, the use of high D.C. voltage across the energy storing capacitors avoid the expense, volume, and weight, of isolating transformer.

Claims (13)

Claims
1. An A.C. power supply conditioner in which the A.C. input supply is rectified and used to charge energy storage capacitor means at a high D.C. voltage (i.e. a voltage comparable with the A.C. supply voltage), and an A.C. output signal is derived from the high D.C. voltage.
2. A supply conditioner as claimed in Claim 1 which does not include a transformer.
3. A supply conditioner as claimed in either of the preceding claims in which the peak A.C. input voltage is rectified and used to charge the capacitor means.
4. A supply conditioner as claimed in Claim 3 in which both the positive and the negative A.C.
peak input voltages are rectified in a voltage doubling arrangement.
5. A supply conditioner as claimed in Claim 4 in which one side of the A.C. input supply is connected through to the A.C. output supply and acts as a centre of the high D.C. voltage.
6. A supply conditioner as claimed in any of the preceding claims in which the A.C. output supply is derived by an inverter of the high D.C. voltage.
7. A supply conditioner as claimed in Claim 6 in which the inverter is of regulated square wave type.
8. A supply conditioner as claimed in Claim 6 in which the inverter is pulse width controlled or pulse width modulated.
9. A supply conditioner as claimed in any of the preceding claims including a battery stand-by system including a low voltage battery and a DC/AC/DC converter coupled to the high D.C.
voltage supply.
1 0. A supply conditioner as claimed in Claim 9 in which the converter includes a high frequency step-up isolating transformer.
1 A supply conditioner as claimed in Claim 9 or Claim 10 including a battery charger driven from the A.C. input supply.
12. A supply conditioner as claimed in any of the preceding claims including a switch arranged to connect the A.C. input supply directly to the A.C. output in response to a failure of the supply conditioner.
13. An A.C. power supply conditioner arranged substantially as herein specifically described with reference to the accompanying drawings.
GB08136142A 1981-12-01 1981-12-01 No-break power supply Expired GB2111326B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08136142A GB2111326B (en) 1981-12-01 1981-12-01 No-break power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08136142A GB2111326B (en) 1981-12-01 1981-12-01 No-break power supply

Publications (2)

Publication Number Publication Date
GB2111326A true GB2111326A (en) 1983-06-29
GB2111326B GB2111326B (en) 1985-07-24

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08136142A Expired GB2111326B (en) 1981-12-01 1981-12-01 No-break power supply

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Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2137833A (en) * 1983-04-08 1984-10-10 Toshiba Kk Uninterruptible power supply
US4709318A (en) * 1986-10-22 1987-11-24 Liebert Corporation UPS apparatus with control protocols
US4751398A (en) * 1986-03-18 1988-06-14 The Bodine Company Lighting system for normal and emergency operation of high intensity discharge lamps
US4779007A (en) * 1987-02-13 1988-10-18 Unison Technologies, Inc. Uninterrupted power supply system
GB2210214A (en) * 1987-09-22 1989-06-01 Chloride Group Plc Uninterrupted power supply
EP0360156A2 (en) * 1988-09-19 1990-03-28 Isao Takahashi Power supply
FR2648285A1 (en) * 1989-06-13 1990-12-14 Exide Elect Int BACKUP SUPPLY SYSTEM WITH NEUTRAL CONTINUITY
WO1990016105A1 (en) * 1989-06-21 1990-12-27 James William Piper Uninterruptible power supplies
EP0420628A2 (en) * 1989-09-29 1991-04-03 Wisconsin Alumni Research Foundation AC to DC to AC power conversion apparatus with few active switches and input and output control
US5099410A (en) * 1990-11-13 1992-03-24 Wisconsin Alumni Research Foundation Single phase ac power conversion apparatus
US5126585A (en) * 1990-06-19 1992-06-30 Auckland Uniservices Limited Uninterruptible power supplies
US5198970A (en) * 1988-04-27 1993-03-30 Mitsubishi Denki Kabushiki Kaisha A.C. power supply apparatus
FR2684250A1 (en) * 1991-11-27 1993-05-28 Merlin Gerin High-quality electrical energy distribution system
US5402053A (en) * 1993-08-26 1995-03-28 Wisconsin Alumni Research Foundation Single phase to three phase converter capable of variable speed motor operation
US5610805A (en) * 1995-01-10 1997-03-11 Cambridge Continuous Power Uninterruptible power supply with a back-up battery coupled across the a.c. input
US5654591A (en) * 1993-11-24 1997-08-05 Schneider Electric Sa Uninterruptible power supply with passing neutral, comprising a twin step-up chopper
EP0866538A2 (en) * 1995-08-23 1998-09-23 Litton Systems, Inc. Uninterruptible power supply
US5969957A (en) * 1998-02-04 1999-10-19 Soft Switching Technologies Corporation Single phase to three phase converter
WO2001088637A1 (en) * 2000-05-18 2001-11-22 High Technology Investments B.V. Drive unit comprising a device for the controlled and/or modulated gradual slow-down and shut-down of a funicular
US6570778B2 (en) 2001-08-30 2003-05-27 Wisconsin Alumni Research Foundation Adjustable speed drive for single-phase induction motors
CN101714822B (en) * 2009-12-10 2012-07-04 华北电力大学 Dual H-bridge-based circuit for converting single-phase AC power supply to three-phase AC power supply
CN103001313A (en) * 2011-09-08 2013-03-27 联正电子(深圳)有限公司 Off-line uninterrupted power system
WO2014041523A3 (en) * 2012-09-14 2014-12-11 Chloride Srl Uninterruptible power supply system with fast transfer for undervoltage source line failures

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1428982A (en) * 1972-07-06 1976-03-24 Marconi Co Ltd 3-phase power supply arrangements
GB1497369A (en) * 1975-06-05 1978-01-12 Siemens Ag Current supply system
GB2024544A (en) * 1978-05-08 1980-01-09 Stevens C Power supplies for discharge lamps
GB2036466A (en) * 1978-09-21 1980-06-25 Exxon Research Engineering Co Bridge Type Converter
EP0026039A1 (en) * 1979-08-15 1981-04-01 Fanuc Ltd. Operation control apparatus for AC motors
GB2091052A (en) * 1981-01-14 1982-07-21 Mueller Karl Circuit for controlling electric drives

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1428982A (en) * 1972-07-06 1976-03-24 Marconi Co Ltd 3-phase power supply arrangements
GB1497369A (en) * 1975-06-05 1978-01-12 Siemens Ag Current supply system
GB2024544A (en) * 1978-05-08 1980-01-09 Stevens C Power supplies for discharge lamps
GB2036466A (en) * 1978-09-21 1980-06-25 Exxon Research Engineering Co Bridge Type Converter
EP0026039A1 (en) * 1979-08-15 1981-04-01 Fanuc Ltd. Operation control apparatus for AC motors
GB2091052A (en) * 1981-01-14 1982-07-21 Mueller Karl Circuit for controlling electric drives

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4562357A (en) * 1983-04-08 1985-12-31 Tokyo Shibaura Denki Kabushiki Kaisha Uninterruptible power supply and a starting method
GB2137833A (en) * 1983-04-08 1984-10-10 Toshiba Kk Uninterruptible power supply
US4751398A (en) * 1986-03-18 1988-06-14 The Bodine Company Lighting system for normal and emergency operation of high intensity discharge lamps
US4709318A (en) * 1986-10-22 1987-11-24 Liebert Corporation UPS apparatus with control protocols
US4779007A (en) * 1987-02-13 1988-10-18 Unison Technologies, Inc. Uninterrupted power supply system
GB2210214A (en) * 1987-09-22 1989-06-01 Chloride Group Plc Uninterrupted power supply
US5198970A (en) * 1988-04-27 1993-03-30 Mitsubishi Denki Kabushiki Kaisha A.C. power supply apparatus
EP0360156A3 (en) * 1988-09-19 1991-09-18 Isao Takahashi Power supply
EP0360156A2 (en) * 1988-09-19 1990-03-28 Isao Takahashi Power supply
FR2648285A1 (en) * 1989-06-13 1990-12-14 Exide Elect Int BACKUP SUPPLY SYSTEM WITH NEUTRAL CONTINUITY
WO1990016105A1 (en) * 1989-06-21 1990-12-27 James William Piper Uninterruptible power supplies
AU636364B2 (en) * 1989-06-21 1993-04-29 Auckland Uniservices Limited Pninterruptible power supplies
EP0420628A2 (en) * 1989-09-29 1991-04-03 Wisconsin Alumni Research Foundation AC to DC to AC power conversion apparatus with few active switches and input and output control
EP0420628A3 (en) * 1989-09-29 1991-08-28 Wisconsin Alumni Research Foundation Ac to dc to ac power conversion apparatus with few active switches and input and output control
US5017800A (en) * 1989-09-29 1991-05-21 Wisconsin Alumni Research Foundation AC to DC to AC power conversion apparatus with few active switches and input and output control
US5126585A (en) * 1990-06-19 1992-06-30 Auckland Uniservices Limited Uninterruptible power supplies
EP0486130A2 (en) * 1990-11-13 1992-05-20 Wisconsin Alumni Research Foundation Single phase AC power conversion apparatus
EP0486130A3 (en) * 1990-11-13 1992-09-02 Wisconsin Alumni Research Foundation Single phase ac power conversion apparatus
US5099410A (en) * 1990-11-13 1992-03-24 Wisconsin Alumni Research Foundation Single phase ac power conversion apparatus
FR2684250A1 (en) * 1991-11-27 1993-05-28 Merlin Gerin High-quality electrical energy distribution system
EP0550348A1 (en) * 1991-11-27 1993-07-07 Schneider Electric Sa High quality electrical power distribution system
US5477091A (en) * 1991-11-27 1995-12-19 Merlin Gerin High quality electrical power distribution system
US5402053A (en) * 1993-08-26 1995-03-28 Wisconsin Alumni Research Foundation Single phase to three phase converter capable of variable speed motor operation
EP0654887B1 (en) * 1993-11-24 2004-02-04 Mge-Ups Systems Uninterruptible power supply with common neutral line comprising a double boost switching converter
US5654591A (en) * 1993-11-24 1997-08-05 Schneider Electric Sa Uninterruptible power supply with passing neutral, comprising a twin step-up chopper
US5610805A (en) * 1995-01-10 1997-03-11 Cambridge Continuous Power Uninterruptible power supply with a back-up battery coupled across the a.c. input
EP0866538A3 (en) * 1995-08-23 1999-07-07 Litton Systems, Inc. Uninterruptible power supply
EP0866538A2 (en) * 1995-08-23 1998-09-23 Litton Systems, Inc. Uninterruptible power supply
US5969957A (en) * 1998-02-04 1999-10-19 Soft Switching Technologies Corporation Single phase to three phase converter
WO2001088637A1 (en) * 2000-05-18 2001-11-22 High Technology Investments B.V. Drive unit comprising a device for the controlled and/or modulated gradual slow-down and shut-down of a funicular
US6570778B2 (en) 2001-08-30 2003-05-27 Wisconsin Alumni Research Foundation Adjustable speed drive for single-phase induction motors
CN101714822B (en) * 2009-12-10 2012-07-04 华北电力大学 Dual H-bridge-based circuit for converting single-phase AC power supply to three-phase AC power supply
CN103001313A (en) * 2011-09-08 2013-03-27 联正电子(深圳)有限公司 Off-line uninterrupted power system
CN103001313B (en) * 2011-09-08 2015-07-22 联正电子(深圳)有限公司 Off-line uninterrupted power system
WO2014041523A3 (en) * 2012-09-14 2014-12-11 Chloride Srl Uninterruptible power supply system with fast transfer for undervoltage source line failures
US9362781B2 (en) 2012-09-14 2016-06-07 Chloride Srl Uninterruptible power supply system with fast transfer for undervoltage source line failures

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