AU2001252159B2 - Electronic transformer - Google Patents

Electronic transformer Download PDF

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Publication number
AU2001252159B2
AU2001252159B2 AU2001252159A AU2001252159A AU2001252159B2 AU 2001252159 B2 AU2001252159 B2 AU 2001252159B2 AU 2001252159 A AU2001252159 A AU 2001252159A AU 2001252159 A AU2001252159 A AU 2001252159A AU 2001252159 B2 AU2001252159 B2 AU 2001252159B2
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AU
Australia
Prior art keywords
switches
halogen lamp
low
voltage
dimming
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.)
Ceased
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AU2001252159A
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AU2001252159A1 (en
Inventor
Alexander Mair
Heinz Studer
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.)
Tridonicatco GmbH and Co KG
Original Assignee
Tridonicatco GmbH and Co KG
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Filing date
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Publication of AU2001252159A1 publication Critical patent/AU2001252159A1/en
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Publication of AU2001252159B2 publication Critical patent/AU2001252159B2/en
Anticipated expiration legal-status Critical
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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/337Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration
    • H02M3/3376Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B39/00Circuit arrangements or apparatus for operating incandescent light sources
    • H05B39/04Controlling
    • H05B39/041Controlling the light-intensity of the source
    • H05B39/044Controlling the light-intensity of the source continuously
    • H05B39/045Controlling the light-intensity of the source continuously with high-frequency bridge converters
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The invention relates to an electronic transformer for operating at least one low-volt halogen lamp (L). The inventive transformer contains an inverse rectifier (3) having two switches (V1, V2) that can be switched-on and off for providing an alternating output voltage. Said transformer also comprises a control circuit (uC) for controlling the switching-on and switching-off behaviour of the two switches (V1, V2) pertaining to the inverse rectifier. Said electronic transformer further comprises a transformer (4, Tp, Ts1, Ts2) which is connected to the inverse rectifier (3) on the input side. A load circuit that is provided with the at least one low-voltage halogen lamp (L) is connected to the output side of said transformer (4, Tp, Ts1, Ts2). The aim of the invention is to dim the low-volt halogen lamp (L). The pulse duty factor for the two switches (V1, V2) is changed by means of the dead time (ttot) remaining constant between the opening of one of the two switches (V1) and subsequently closing the remaining switch (V2) and by reducing the make-time (tein) respectively. Silent dimming is thus made possible.

Description

ELECTRONIC TRANSFORMER The present invention concerns an electronic transformer or, that is to say, an electronic converter, for operating at least one low-voltage halogen lamp; having an inverter with two switches capable of being switched on and off, for providing an alternating output voltage; having a control circuit for controlling the on and off switching behaviour of the two switches of the inverter; and having a transformer, that at the input side is connected to the inverter and to which at the output side is connected a load circuit having the at least one lowvoltage halogen lamp.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
The basic principle of such types of electronic transformers is known from C.H. Sturm/E. Klein "Betriebsgerate und Schaltungen fUr elektrisch Lampen" Siemens Aktiengesellschaft, 1992, pages 295 ff. Their general construction, as well as the mode of operation, is illustrated in Fig. 3. First of all, the electronic transformer has a harmonic filter 1 for radio interference suppression, which at the input side is connected to an alternating voltage source, which in the present example, outputs an alternating supply voltage at a frequency of Hz. Connected to the harmonic filter 1 is a rectifier circuit 2, for example a simple diode circuit, which rectifies the alternating supply voltage. The rectified intermediate circuit voltage produced by the rectifier circuit 2 is finally fed to an inverter 3, which in the usual manner has two switches for example power transistors arranged in a half-bridge circuit, which, according to a specific layout, are switched on and off alternately, so that in this way a voltage that is chopped into rectangular blocks is produced, which is modulated by the rectified mains voltage. The alternating voltage thus produced is transmitted via a transformer 4 to an outputside load circuit and in so doing is transformed into the extra-low voltage required for the low-voltage halogen lamp L arranged in the load circuit. Furthermore, an additional circuit 5 for rectifying, as well as a filter 6 for smoothing the transmitted alternating voltage, is located in the load circuit.
Apart from their basic function to convert the voltage delivered by the supply system into an extra-low voltage suitable for the low-voltage halogen lamp electronic transformers also offer the possibility of operating the lamp in a dimmed mode. The most widely used method for dimming is so-called phase-angle control in which, according to the desired degree of dimming, the two switches of the inverter are triggered during one halfcycle of the rectified alternating supply voltage for only a specific timer period. In this so-called internal dimming of electronic transformers, because of the phase segment large voltage transients can of course occur, which in turn since they have a frequency corresponding to the alternating supply voltage can lead to clearly audible noise.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
This object is achieved in one aspect by an electronic transformer for operating at least one low-voltage halogen lamp; -3having an inverter with two switches capable of being switched on and off, for providing an alternating output voltage; having a control circuit for controlling the on and off switching behaviour of the two switches of the inverter; and having a transformer, that at the input side is connected to the inverter and to which at the output side is connected a load circuit having the at least one lowvoltage halogen lamp; wherein the control circuit for dimming the at least one low-voltage halogen lamp varies the mark-space-ratio for both switches in such a way that the delay time between the opening of one of the two switches and the following closing of the other switch remains constant and the ontime is shortened in each case.
According to another aspect, the present invention provides a process for operating at least one low-voltage halogen lamp by means of an electronic transformer, comprising: an inverter with two switches capable of being switched on and off, for providing an alternating output voltage; a control circuit for controlling the on and off switching behaviour of the two switches of the inverter; and a transformer, that the input side is connected to the inverter and to which at the output side is connected a load circuit having the at least one low-voltage halogen lamp; wherein, for dimming the at least one low-voltage halogen lamp the mark-space-ratio for both switches is varied in such a way that the delay time between the opening of one of the two switches and the following -3aclosing of the other switch remains constant and the ontime is shortened in each case.
According to the invention, the dimming is effected in such a way that the mark-space-ratio for both switches of the inverter is varied, in that the delay time between the opening (switching off) of one of the two switches and the following closing (switching on) of the other switch remains constant and the on-time is shortened in each case.
With this process, in which the two switches of the inverter are constantly triggered, the large voltage transients occurring in phase-angle control can be avoided.
Only the switching frequencies for the two switches are varied so that a reduced r.m.s. voltage corresponding to the desired degree of dimming appears at the output side of the transformer.
In comparison with the other dimming processes, in the case of the process according to the invention, during dimming the switching frequencies are increased by the reduction in the on-times, so that it is possible to operate the half-bridge switches independently of the degree of dimming, in a frequency range that lies above the human limit of audibility and thus causes no noise nuisance. Preferably, both switches are operated in a frequency range between 35 kHz for the undimmed state and 300 kHz for maximum dimming. Moreover, the switches are preferably driven so that their mark-space-ratio is identical.
Maintaining the delay time constant also offers the possibility of triggering the two switches of the inverter in such a way that, irrespective of the set degree of dimming, they each switch at a time instant at which no voltage is applied to them. This corresponds to so-called zero voltage switching in which turn-on losses are avoided.
Thus, due to the present invention, an electronic 3b transformer for operating a low-voltage halogen lamp is specified, which on the one hand has a high efficiency and on the other hand facilitates a noiseless dimming of the lamp.
Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".
The invention will now be explained in further detail below by way of example with the aid of the accompanying drawings, in which: Fig. shows the inverter, transformer and load circuit of the electronic transformer according to the invention; Fig. 2 shows the triggering according to the invention of the two switches of the inverter; and Fig. 3 shows the general construction of an electronic transformer, as it is known from the prior art.
The alternating supply voltage rectified by the rectifier (not shown) is applied to the input of the inverter illustrated in Fig. 1. The triggering of the two switches V1 and V2 arranged in a half-bridge arrangement, which involves power transistors or field-effect transistors, is effected by a half-bridge driver HB, which in turn is controlled by a control circuit jC in the form of a microprocessor. The two switches Vl and V2 are switched on and off alternately, so that at the interconnection point between the two half-bridge capacitors C2 and C3, which are connected in parallel with the two field-effect transistors V1 and V2, a square-wave voltage appears that is modulated by the rectified and half-sinewave intermediate circuit voltage. This alternating voltage is transmitted to the load circuit by the primary winding Tp of a transformer arranged between the interconnecting points of the two switches Vl and V2 and of the two intermediate circuit capacitors C2 and C3. The choke L1 ensures commutation of the current at the secondary side, the capacitor C1 suppresses high-frequency interference.
In the load circuit are located two secondary windings Tsl and Ts2 of the transformer, to whose common node point the low-voltage halogen lamp L is connected. As an alternative to this, a single secondary winding with a centre tap can also be provided. Between the secondary windings Tsl and Ts2 and the low-voltage halogen lamp L is located an LC element formed by a coil L2 and a capacitor C4 and acting as a low-pass filter for smoothing the high-frequency alternating voltage. Furthermore, the load circuit has two diodes D1 and D2, which are arranged in the form of a fullwave rectifier in order to rectify the alternating voltage fed to the low-voltage halogen lamp L.
The triggering according to the invention of the two halfbridge switches Vi and V2 will be explained in more detail below with the aid of Fig. 2, which illustrates the switching states of the two switches for two different dimming stages. Here the upper timing diagram in Fig. 2 shows the switching states of the two half-bridge switches in the undimmed state the full line for the switch V1 and the broken line for the switch V2 while the lower timing diagram illustrates the switching states in a dimmed state.
As already explained, both switches are triggered in such a way that they are switched on or conducting (state 1) and switched off or non-conducting (state 0) alternately, a certain delay time tde± remaining between the opening of one switch and the following closing of the other switch, during which time both switches are switched off. This delay time, among other things, ensures that no shortcircuit can occur due to a simultaneous closing of both switches of the half-bridge. Furthermore, it can of course also happen that each of the two switches switch on without losses at a time instant at which no voltage is applied to them, since due to the reactances contained in the circuit a certain time elapses until the voltage ratios rotate.
Such lossless switching is also termed "zero switching loss" or "zero voltage switch" and can lead to an appreciable increase in the efficiency.
The mark-space-ratio for the two switches is determined by the ratio between the on-time and the off-time to 0 t. Here a highest possible mark-space-ratio is selected for the undimmed state illustrated above, which preferably corresponds to a switching frequency f of approximately kHz, the same mark-space-ratio being set for both switches.
According to the invention, the dimming of the low-voltage halogen lamp occurs in such a way that the duration of the delay time tdel is retained and only the on-time to, is equally reduced for both switches. As a result of this, the switching frequency f is on the whole increased, as can be seen in the lower timing diagram in Fig. 2. If, for example, in the undimmed state at a frequency of 35 kHz an output-side voltage of 12 volts r.m.s. is obtained, then by increasing the switching frequency to 300 kHz, a reduction in the output-side voltage of 4 volts r.m.s. can be achieved, which results in the low-voltage halogen lamp being set to approximately 1 of its maximum light output.
Generally speaking, the entire dimming range for the lowvoltage halogen lamp can essentially be covered by increasing the base frequency, that is to say the frequency existing in the undimmed mode, by the factor of 7 to 12.
In contrast to the previously known processes, the switching frequency is again increased by the dimming, so that it is shifted into a frequency range that is far removed from the human limit of audibility. Since in the undimmed state the existing 35 kHz already lies in the ultrasonic range, and therefore is usually imperceptible, a simple and effective dimming that leads to no noise nuisance is realised in this manner. Since, however, as before, the delay time tde, is held constant, zero switching can also be achieved in the dimmed state for the two halfbridge switches, so that the electronic transformer according to the invention has an extraordinarily high efficiency.

Claims (10)

1. An electronic transformer for operating at least one low-voltage halogen lamp; having an inverter with two switches capable of being switched on and off, for providing an alternating output voltage; having a control circuit for controlling the on and off switching behaviour of the two switches of the inverter; and having a transformer, that at the input side is connected to the inverter and to which at the output side is connected a load circuit having the at least one low- voltage halogen lamp; wherein the control circuit for dimming the at least one low-voltage halogen lamp varies the mark-space-ratio for both switches in such a way that the delay time between the opening of one of the two switches and the following closing of the other switch remains constant and the on- time is shortened in each case.
2. An electronic transformer according to claim 1, wherein, irrespective of the degree of dimming, the switching frequencies of the two switches lie above the human limit of audibility.
3. An electronic transformer according to claim 2, wherein, at maximum dimming, the switching frequency of the two switches is approximately 10 times higher than the switching frequency in the undimmed mode.
4. An electronic transformer according to claim 3, wherein, the switching frequencies of the two switches lie between 35 kHz and 300 kHz. An electronic transformer according to any one of the preceding claims, wherein, the mark-space-ratio is identical for both switches.
6. A process for operating at least one low-voltage halogen lamp by means of an electronic transformer, comprising: an inverter with two switches capable of being switched on and off, for providing an alternating output voltage; a control circuit for controlling the on and off switching behaviour of the two switches of the inverter; and a transformer, that the input side is connected to the inverter and to which at the output side is connected a load circuit having the at least one low-voltage halogen lamp; wherein, for dimming the at least one low-voltage halogen lamp the mark-space-ratio for both switches is varied in such a way that the delay time between the opening of one of the two switches and the following closing of the other switch remains constant and the on- time is shortened in each case.
7. A process according to claim 6, wherein, irrespective of the degree of dimming, the switching frequencies of the two switches lie above the human limit of audibility.
8. A process according to claim 6 or 7, wherein, at maximum dimming, the switching frequency of the two switches is approximately 10 times higher than the switching frequency in the undimmed mode.
9. A process according to claim 8, wherein, the switching frequencies of the two switches lie between 35 kHz and 300 kHz. -9- A process according to any one of claims 5 to 9, wherein, the mark-space-ratio is identical for both switches.
11. An electronic transformer substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings.
12. A process substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings. DATED this 5 th November, 2003 BALDWIN SHELSTON WATERS Attorneys for: TRIDONICATCO GMBH CO. KG
AU2001252159A 2000-03-14 2001-03-06 Electronic transformer Ceased AU2001252159B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10012363.5 2000-03-14
DE10012363A DE10012363A1 (en) 2000-03-14 2000-03-14 Electronic transformer
PCT/EP2001/002510 WO2001069983A1 (en) 2000-03-14 2001-03-06 Electronic transformer

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AU2001252159A1 AU2001252159A1 (en) 2001-12-06
AU2001252159B2 true AU2001252159B2 (en) 2005-02-24

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AU2001252159A Ceased AU2001252159B2 (en) 2000-03-14 2001-03-06 Electronic transformer

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EP (1) EP1266545B1 (en)
AT (1) ATE257316T1 (en)
AU (2) AU5215901A (en)
DE (2) DE10012363A1 (en)
NZ (1) NZ520991A (en)
WO (1) WO2001069983A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10146030A1 (en) * 2001-09-18 2003-04-03 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Ballast for at least one electric light bulb
US7019469B1 (en) * 2004-10-21 2006-03-28 Electronic Theatre Controls, Inc. Sinewave dimmer control method
US7489090B2 (en) 2006-02-13 2009-02-10 Lutron Electronics Co., Inc. Electronic ballast having adaptive frequency shifting
DE202007018812U1 (en) * 2006-09-08 2009-07-16 Schiederwerk Mbz Telekommunikation Gmbh & Co Kg dimmer circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4922397A (en) * 1988-02-16 1990-05-01 Digital Equipment Corporation Apparatus and method for a quasi-resonant DC to DC bridge converter
DE4126544A1 (en) * 1991-08-10 1993-02-11 Dresden Messelektronik Gmbh Stabilised electronic half-wave converter for resistive load e.g. halogen lamp - has power switching stages controlled by circuit providing pulse width modulated regulation
DE29517392U1 (en) * 1995-11-03 1996-02-15 Huegler Gmbh Electronic transformer 200 W for the operation of low-voltage halogen lamps in ABS housing, with connection terminal for 230 V AC input and 12 V DC output

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992013385A1 (en) * 1991-01-29 1992-08-06 Dan Harry Dawari Datubo High frequency, high density power conversion system
DE4243957A1 (en) * 1992-12-23 1994-06-30 Tridonic Bauelemente Ges Mbh D Power supply and brightness control for LV halogen lamps
DE4433552B4 (en) * 1994-09-06 2004-01-15 Marx, Peter, Prof. Dr.-Ing. Electronic HF dimmer for high and low voltage light bulbs
DE19543720A1 (en) * 1995-11-23 1997-05-28 Tridonic Bauelemente Electronic transformer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4922397A (en) * 1988-02-16 1990-05-01 Digital Equipment Corporation Apparatus and method for a quasi-resonant DC to DC bridge converter
DE4126544A1 (en) * 1991-08-10 1993-02-11 Dresden Messelektronik Gmbh Stabilised electronic half-wave converter for resistive load e.g. halogen lamp - has power switching stages controlled by circuit providing pulse width modulated regulation
DE29517392U1 (en) * 1995-11-03 1996-02-15 Huegler Gmbh Electronic transformer 200 W for the operation of low-voltage halogen lamps in ABS housing, with connection terminal for 230 V AC input and 12 V DC output

Also Published As

Publication number Publication date
NZ520991A (en) 2003-04-29
WO2001069983A1 (en) 2001-09-20
ATE257316T1 (en) 2004-01-15
EP1266545A1 (en) 2002-12-18
AU5215901A (en) 2001-09-24
DE10012363A1 (en) 2001-10-11
EP1266545B1 (en) 2004-01-02
DE50101266D1 (en) 2004-02-05

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