GB2470583A - Half bridge inverter having reduced in-rush current - Google Patents

Half bridge inverter having reduced in-rush current Download PDF

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Publication number
GB2470583A
GB2470583A GB0909132A GB0909132A GB2470583A GB 2470583 A GB2470583 A GB 2470583A GB 0909132 A GB0909132 A GB 0909132A GB 0909132 A GB0909132 A GB 0909132A GB 2470583 A GB2470583 A GB 2470583A
Authority
GB
United Kingdom
Prior art keywords
supply
capacitor
voltage
inverter
electronic
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.)
Withdrawn
Application number
GB0909132A
Other versions
GB0909132D0 (en
Inventor
Charles Pollock
Helen Geraldine Phyllis Pollock
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.)
Holdip Ltd
Original Assignee
Holdip Ltd
Technelec 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 Holdip Ltd, Technelec Ltd filed Critical Holdip Ltd
Priority to GB0909132A priority Critical patent/GB2470583A/en
Publication of GB0909132D0 publication Critical patent/GB0909132D0/en
Publication of GB2470583A publication Critical patent/GB2470583A/en
Withdrawn legal-status Critical Current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
    • 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
    • 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
    • H02M7/5387—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 bridge configuration
    • H05B33/0815—
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
    • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
    • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2981—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • 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
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

An electronic power supply, particularly for a fluorescent or LED lamp, comprises a half bridge inverter Sl, S2and a capacitor C1connected across a DC supply. An electronic network 200 provides power to the load RL. One input terminal 101 of the electronic network is connected to the centre point of the half bridge inverter and the second input terminal 102 is connected to a second capacitor CDC2. The other end of the second capacitor is connected to either terminal of the DC supply, such that the voltage across the second capacitor is less that the DC supply voltage. The electronic network may be a resonant circuit. The arrangement is particularly suitable for reducing the in-rush current associated with TRIAC controlled, rectified supplies.

Description

Reduced In-Rush Current For Half Bridge Inverters The present invention relates to improved design of half bridge inverter circuits to minimise in-rush currents when the circuit is first switched on. The circuit is particularly suited to half bridge inverters driving a resonant circuit connected to a lighting load.
The need for higher efficiency lighting circuits has accelerated the development of electronic ballasts for fluorescent lamps and electronic power supplies for solid state LEDs. Such electronic circuits often contain high frequency inverters with dc energy storage using capacitors. In more traditional lighting applications it is common to use a triac to vary the applied supply voltage to a lamp to vary its brightness. It is desirable therefore if the newer power supplies can be designed to operate from the same triac controlled voltage supplies used in lighting circuits, while retaining the higher efficiency benefits of fluorescent or solid state LED systems.
However it has been discovered that an electronic power supply with dc energy storage in capacitors will draw a substantial in-rush current through the triac when the triac is fired at voltages away from zero voltage. Suppression of the in-rush current with an input inductor can lead to an LC oscillation with the dc capacitors in the power supply, overcharging the capacitors above the ac supply voltage.
The in-rush current is therefore forced back to zero and the triac conduction is prematurely terminated. Furthermore, if the triac is fired near the peak of the ac supply voltage the in-rush current is large and the resulting LC resonance can charge the dc capacitors to twice the normal peak voltage applying excessive voltage to other components in the circuit.
It is the object of this invention to provide a simple modification which can be applied to electronic power supplies of the type used to drive electronic ballasts and power supplies for solid state lighting, which substantially eliminate the need for in-rush current limiting and which allows the triac to remain in conduction every time it is activated.
According to this invention there is provided an electronic power supply comprising a half bridge inverter connected across the two terminals of a dc supply to the inverter, including a first capacitor connected across the two terminals of the dc supply to the inverter, an electronic network to supply power to a load, one input terminal of the electronic network connected to the centre point of the half bridge inverter, the second input terminal of the electronic network connected to a second capacitor, the other end of the second capacitor connected to either terminal of the dc supply. such that the voltage on the second capacitor is less than the voltage across the two terminals of the dc supply to the inverter.
According to a second aspect of the invention an electronic power supply is provided wherein the voltage on the second capacitor is less than the voltage across the dc supply to the inverter.
According to a third aspect of the invention an electronic power supply is provided wherein the capacitance of the second capacitor is greater than the capacitance of the first capacitor.
The invention will now be described with reference to the following Figures in which Figure 1 shows a typical electronic power supply used to drive a fluorescent or solid state lighting; Figure 2 shows a circuit according to the invention.
Figure 1 shows a circuit commonly used in the lighting industry to drive electronic ballasts for fluorescent lamps or electronic power supplies for LEDs. A dc supply which often is obtained by rectification of an ac supply is applied to an inverter leg comprising two switching transistors with internal diodes. The centre point of the two transistors is connected to the first input connection 101 of an electronic network 200. The second input connection 102 of the electronic network is connected to the mid-point of two voltage dividing capacitors Cc and CDC2 which split the DC supply from the rectifier into two approximately equal values. This allows the alternate switching of the two transistors to provide alternating positive and negative voltages across the input terminals of the electronic network. To avoid excessive fluctuation of the voltage at the centre point 102 of the two capacitors it is usual that the energy stored in the dc capacitors should be greater than the energy delivered to the electronic network in each half cycle of the switching cycle. The output terminals 103 and 104 of the electronic network would be connected to a fluorescent lamp or to a string of solid state LED5, each requiring its own appropriate voltage and current range and ac or dc as appropriate.
In lighting applications with traditional filament lamps it is common to use a triac to vary the applied supply voltage to a lamp to vary its brightness. It is desirable therefore if the newer power supplies can be designed to operate from the same triac controlled voltage supplies used in lighting circuits.
However it has been discovered that if the power supply shown in Figure 1 is powered from a rectifier circuit which in turn is connected to a triac controlled ac supply dc energy storage capacitors will draw a substantial in-rush current through the triac when the triac is fired at voltages away from zero voltage. This initial surge of energy is many times the normal energy requirement of the lamp.
Suppression of the in-rush current with an input inductor can lead to an LC oscillation with the dc capacitors in the power supply, overcharging the capacitors above the ac supply voltage. The in-rush current is therefore forced back to zero after a half cycle of the LC oscillation and the triac conduction is prematurely terminated. Furthermore, if the triac is fired near the peak of the ac supply voltage the in-rush current is large and the resulting LC resonance can charge the dc capacitors to twice the normal peak voltage applying excessive voltage to other components in the circuit.
Figure 2 shows a circuit modified according to the invention which significantly reduces the inrush current and allows these lighting power supplies to be used directly on triac controlled supplies. The pair of energy storage capacitors across the dc link in figure 1 are replaced by a smaller single capacitor, C1 connected across the supply and a single larger capacitor CDC2. The capacitor Cl can now be sized appropriately for the decoupling of the dc supply without concern of the stabilisation of the mid-point voltage at terminal 102. This means that it can be a smaller value, storing energy equivalent to the energy delivered over several cycles of the electronic network. The in-rush current to the smaller capacitor C1 can more easily be limited so that the triac switching is not impaired. The single capacitor CDC2 can be larger and will naturally charge to a value approximately half the dc supply during the alternate switching cycles of the inverter. Since there is no charging path from the ac supply through to the capacitor CDC2 this capacitor does not draw any in-rush charging current.
A circuit according to this invention is particularly suited to driving solid state LEDs from a triac controlled ac supply. The electronic network may be a resonant circuit. In such a case it is useful that the value of CDC2 can be large enough so that it provides a relatively stable node voltage to the resonant electronic network without changing the resonant frequency. This invention therefore solves the problem of using such circuits on a triac controlled ac supply.
As an alternative embodiment to Figure 2, the capacitor CDC1 can be retained from Figure 1 and the capacitor CDC2 removed. CDC1 is connected between the positive supply voltage to the inverter and the second terminal 102 of the electronic network. The position of Cl in Figure 2 is the same.

Claims (5)

  1. Claims 1. An electronic power supply comprising a half bridge inverter connected across the two terminals of a dc supply to the inverter, including a first capacitor connected across the two terminals of the dc supply to the inverter, an electronic network to supply power to a load, one input terminal of the electronic network connected to the centre point of the half bridge inverter, the second input terminal of the electronic network connected to a second capacitor, the other end of the second capacitor connected to either terminal of the dc supply. such that the voltage on the second capacitor is less than the voltage across the two terminals of the dc supply to the inverter.
  2. 2. An electronic power supply according to Claim 1 wherein the voltage on the second capacitor is less than the voltage across the dc supply to the inverter.
  3. 3. An electronic power supply according to Claim 1 or Claim 2 wherein the capacitance of the second capacitor is greater than the capacitance of the first capacitor.
  4. 4. An electronic power supply according to Claim 1, 2 or 3 wherein the second terminal of the second capacitor is connected to the negative supply of the dc supply connected to the inverter.
  5. 5. An electronic power supply according to Claim 1, 2 or 3 wherein the second terminal of the second capacitor is connected to the positive supply of the dc supply connected to the inverter.
GB0909132A 2009-05-28 2009-05-28 Half bridge inverter having reduced in-rush current Withdrawn GB2470583A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0909132A GB2470583A (en) 2009-05-28 2009-05-28 Half bridge inverter having reduced in-rush current

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0909132A GB2470583A (en) 2009-05-28 2009-05-28 Half bridge inverter having reduced in-rush current

Publications (2)

Publication Number Publication Date
GB0909132D0 GB0909132D0 (en) 2009-07-01
GB2470583A true GB2470583A (en) 2010-12-01

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Family Applications (1)

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GB0909132A Withdrawn GB2470583A (en) 2009-05-28 2009-05-28 Half bridge inverter having reduced in-rush current

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6353545B1 (en) * 1998-12-28 2002-03-05 Kabushiki Kaisha Yaskawa Denki Inverter apparatus with active current limiting and smoothing circuit
US20020191426A1 (en) * 2000-11-30 2002-12-19 Hussein Khalid Hassan Inrush current limiting circuit, power source device and power conversion device
US20080143271A1 (en) * 2004-02-26 2008-06-19 Akira Takahashi Lamp-Operating Unit and Low-Pressure Mercury Discharge Lamp

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6353545B1 (en) * 1998-12-28 2002-03-05 Kabushiki Kaisha Yaskawa Denki Inverter apparatus with active current limiting and smoothing circuit
US20020191426A1 (en) * 2000-11-30 2002-12-19 Hussein Khalid Hassan Inrush current limiting circuit, power source device and power conversion device
US20080143271A1 (en) * 2004-02-26 2008-06-19 Akira Takahashi Lamp-Operating Unit and Low-Pressure Mercury Discharge Lamp

Also Published As

Publication number Publication date
GB0909132D0 (en) 2009-07-01

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Owner name: HOLDIP LIMITED

Free format text: FORMER OWNER: TECHNELEC LTD

WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)