[0001] The present invention relates to the field of driving dimmable illuminants and in
particular to the field of dimmable LED converters, to luminaries equipped with LED
converters and the respective interfaces.
[0002] Dimming of an illuminant (light source) offers the capability to adapt the characteristics
of light emission to the intentions of a user. For example the light intensity may
be adapted or varied according to the settings of a dimming switch or a control unit
offering the capability to control light in theaters or other architectural installations.
Dimming of illuminants and in particular of light emitting diodes (LED) offer the
capability to vary the color temperature of light over a given range by mixing the
respectively dimmed light of multiple illuminants.
[0003] There exist different methods and a plurality of different protocols for dimming
a light source, for example by an analogue signal with a DC voltage range from 1V
to 10 V (0-10V lighting control), by a standardized interface such as the DALI™ standard
for lighting control (IEC 62386) or any other of a plurality protocols which may be
used in conjunction with Ethernet. Another conventional method for dimming a light
source is phase control (PFC) or phase cutting, which basically corresponds to a method
of pulse width modulation (PWM) applied for power limiting of an AC voltage.
[0004] For lighting applications safety requirements concerning insulation of electrical
components and entire lighting systems in order to protect against electrical shock
have to be maintained. The international electrical commission (IEC) and its member
organizations define limits for the electrical potential of any conductor against
earth (ground) which electrical circuits have to comply with.
[0005] Generally known operating devices providing power supply to illuminants thus often
have galvanic isolation between a low-voltage area and a high-voltage area of the
device. Publication
US 2014/327366 discloses a system comprising an illuminant and dimmable converter, and having galvanic
isolation.
[0006] Extra-low voltage (ELV) in electricity supply is one of several means to protect
against electrical shock. In an ELV circuit, an electrical potential of any conductor
against earth (ground) is not more than either 25 volts RMS (35 volts peak) for alternating
current (AC current), or ripple-free 60 volts for direct current (DC current) under
dry conditions.
[0007] Being one of the defined types of ELV systems being distinguished by their respective
safety properties, a SELV system is defined as an electrical system in which the voltage
cannot exceed ELV under normal conditions, and under single-fault conditions, including
earth faults in other circuits.
[0008] The acronym: "SELV" stands for "separated extra-low voltage" in installation standards
such as BS 7671 and for "safety extra-low voltage" in appliance standards, e.g. BS
EN 60335.
[0009] A SELV circuit must have -inter alia- protective-separation, for example double insulation,
reinforced insulation or protective screening from all circuits that might carry higher
voltages, and simple separation from other SELV systems, and other systems with lower
voltages (PELV systems) and from earth (ground).
[0010] Means to achieve the required safety of a SELV circuit is provided by the extra-low
voltage, the low risk of accidental contact with a higher voltage, and a lack of a
return path through earth (ground) that electric current could take in case of contact
with a human body. Hence the design of a SELV circuit typically involves an isolating
transformer and respective electrical isolation barriers (SELV barriers).
[0011] In particular two-stage operating devices for light sources are known, in which a
converter which drives the illuminant as a light emitting element is operated with
potential isolation via a control circuit on the mains voltage side (primary side)
of the potential isolation. If the converter also includes transmitting a feedback
signal from the secondary side of the potential isolation, in particular from the
illuminant, to the control circuit, potential isolation is likewise required for the
feedback line transmitting the feedback signal. The secondary side of the potential
isolation is controlled by a further control circuit, which is isolated from the first-mentioned
control circuit, which is connected to the mains voltage potential.
[0012] An illuminant may be for example a light emitting diode (LED) or a high intensity
discharge lamp (HDI). An operating device may be a LED converter adapted to driving
at least one LED.
[0013] International application publication
WO 2010/051984 A2 discloses an illuminant operating appliance with potential isolation. The operating
appliance comprises a first converter, a second converter galvanically isolated from
the first converter by a SELV barrier and supplying a load circuit with the illuminant.
A first logic circuit for controlling the first converter and a second control circuit
controlling the second converter respectively are interconnected by an interface which
separates the electric potentials of the first and second control circuits. The electrically
isolated interface may include for example an integrated coil, an integrated air coil,
an external transformer or a piezo transformer for maintaining the integrity of a
SELV barrier.
[0014] Conventionally a buck stage or an optocoupler is used in order to transfer a dimming
signal through a SELV barrier.
[0015] Patent application publication
EP 1 871 144 A1 discloses a LED driver arrangement including a switching mode stage to generate a
drive current for feeding one or more LEDs from a DC input. The switching mode stage
may for example be implemented by a circuit topology functioning as a buck stage.
A current sensor senses the drive current and generates a feedback signal indicative
of the intensity of the drive current. The feedback signal is compared with a reference
value indicative of a LED drive current corresponding to an LED brightness as requested
by a user and a control signal is generated which is able to drive control circuitry
in order to generate a drive current corresponding to the requested LED drive current
in the switching mode stage. Galvanic isolation between the LED driver on one hand
and the current sensor, reference value comparing units co-located with the LEDs is
ensured by a respective internal layout of the switching mode stage on one hand, and
by feeding the feedback signal via an optocoupler (photocoupler) from the interface
side receiving a dimming signal to the control circuitry for controlling the switching
mode stage at the regulating side.
[0016] However, the conventional solution requires transferring the analog dimming signal
by means of an optocoupler. If however a dimmer with a dimming interface for a 1V
to 10V dimming signal and an AC supply input interface which is only basically insulated
against the dimming interface is connected with the conventional dimmable converter,
the insulation of the dimmable converter is also impaired. The lighting system including
the dimmer, the dimmable converter and the illuminant as whole then violates the requirement
of double insulation.
[0017] Hence it is an object of the invention to improve the dimmable converter as known
from prior art in particular with respect to its combination with available dimmers
and compensating for its deficiencies.
[0018] The invention solves the above problem by the dimmable converter according to the
independent claim.
[0019] A dimmable converter for driving an illuminant according to the invention comprises
a primary side switched isolated power converter stage. A switch is arranged on a
primary side of the isolated power converter stage and a control circuit is configured
to control an on/off switching of the switch. The control circuit is arranged either
on the primary side or on a secondary side of the isolated power converter stage.
Further an interface for being supplied with a dimming signal, wherein the interface
is isolated both against the primary side and the secondary side of the isolated power
converter stage. The interface comprises an interface control circuit which is supplied
with a current signal transmitted from the secondary side of the isolated power converter
stage, wherein the current signal indicates a current flow on the secondary side of
the isolated power converter stage, and the current signal is transmitted using an
isolated signal transmission means. The interface control circuit generates a control
signal transmitted to the control circuit of the isolated power converter stage.
[0020] The solution provides the advantage of being compliant with different kinds of dimmer
providing the dimming information and achieving electric safety independent from the
dimmer for the dimmable converter. The inventive approach maintains the dimmable converter's
SELV compliant output or double-insulation. This offers additional benefits in luminary
design while maintaining safety regulations. The selection range of dimmer units for
use with the dimmable converter is broadened without needing to make concessions in
the matter of safety.
[0021] The proposed solution offers furthermore independence from the circuit topology in
the dimmable converter, for example buck topology, LLC resonant, etc.... Even more,
the solution offers good linearity for the dimming curve realized by the dimmable
converter as will be shown with respect to the embodiment.
[0022] The dimmable converter according to a preferred embodiment comprises a further isolated
transmission means configured to transmit the control signal to the control means.
[0023] A further advantageous embodiment of the dimmable converter is characterized by the
isolated transmission means and/or further isolated transmission means including either
a transformer and/or an optocoupler.
[0024] Furthermore the dimmable converter has the isolated power converter stage including
a compensating means configured to compensate non-linear characteristics of the optocoupler
and/or aging effects of the optocoupler. The compensating means may form part of the
interface, the primary side of the isolated power converter stage or the secondary
side of the isolated power converter stage.
[0025] The dimmable converter according to an embodiment has the isolated signal transmission
means being arranged for transmitting the current signal from the secondary side of
the power converter stage to the interface.
[0026] In another embodiment of the dimmable converter, the further isolated signal transmission
means is arranged for transmitting the control signal from the interface to the primary
side of the isolated power converter stage.
[0027] The dimmable converter of an embodiment shows the current signal indicating a current
flow driving the illuminant. In particular the current signal may indicate a current
value of the current flow on the secondary side of the isolated power converter stage
driving the illuminant.
[0028] In an embodiment of the dimmable converter according to the invention the interface
control circuit is configured to further obtain a dimming signal received by the interface.
[0029] The dimmable converter according to an embodiment has the control circuit of the
isolated power converter stage being configured to regulate the current flow to the
illuminant in a feedback loop including at least a part of the primary side of the
isolated power converter stage at a preset value, when the control circuit receives
no control signal from the interface control circuit.
[0030] The problem is further solved by a light (luminary) comprising an illuminant and
adapted for replacing a conventional illuminant, wherein the light comprises the dimmable
converter according to any one of the embodiments. The conventional illuminant is
for example an incandescent or halogen light source. The conventional illuminant may
be driven via an existing dimmer switch. Employing the inventive dimmable converter
layout enables replacing the conventional illuminant without needing to take the insulation,
e.g. only basic insulation of the existing dimmer unit into account. The isolated
interface stage of the inventive converter maintains even in this case the required
safety level.
[0031] The dimmable converter with an isolated interface is explained in more detail with
reference to the attached figures, wherein
Figure 1 depicts a schematic drawing of a first embodiment,
Figure 2 depicts a schematic drawing of a second embodiment, and
Figure 3 shows a circuit diagram of a conventional converter circuit.
[0032] In the figures same numerals denote the same elements and a description of the same
elements is not necessarily repeated in the following description of the figures.
[0033] In fig. 1 an embodiment of a dimmable converter is shown. The dimmable converter
1 is without restricting the generality depicted as driving a LED as an illuminant
14. The LED 14 is supplied with a DC current via the output lines V
0+ and V
0- 15.1, 15.2.
[0034] The dimmable LED converter 1 is connected to mains supply with phase line L 3.1,
neutral line N 3.2 and protective earth (ground) line PE 3.3.
[0035] The dimmable LED converter further receives a dimming signal via dimming signal line
17.1. In the depicted case the dimming signal 17.1 is an analogue signal against ground
level 17.2 in the form of a 0V to 10V dimming signal. The dimming signal carries dimming
information defining a desired level of light to be emitted by an illuminant 14.
[0036] The embodiment separates the dimmable LED converter 1 into three substages which
are each electrically isolated against each other. The dimmable converter 1 comprises
as a first substage a primary side 4 of the converter stage for receiving a mains
supply 3.1, 3.2, 3.3. The second substage is represented by a secondary side 6 of
the converter stage for supplying the LED drive current 15.1, 15.2. The third substage
of the dimmable LED converter 1 is the interface 8 for receiving the dimming signal
17.1, 17.2.
[0037] The first, second and third substages of the dimmable LED converter are each isolated
against each other by the isolation barriers (SELV barriers) 18.1, 18.2.
[0038] The primary side 4 of the power converter stage includes a mains input unit 2 for
receiving the mains supply L, N and protective earth PE. The mains supply transfers
the input signal to the mains rectification and filter unit 10 via lines 5.1, 5.2.
The mains rectification and filter unit 10 rectifies the received AC voltage, filters
undesired signal components and provides a DC signal via lines 7.1, 7.2 to the power
conversion means 12. The power conversion means 12 is for example implemented by a
buck converter circuit topology.
[0039] The power conversion means 12 internally provides galvanic isolation between the
input and the output of the power conversion means 12.
[0040] The power conversion means 12 outputs for example a pulse width modulated (PWM-)
signal 11 to an output rectification and filter unit 12 arranged on the secondary
side 6 of the power converter stage. The output rectification and filter unit 12 provides
the drive current to the illuminant 14. Further the pulse width (PWM-) signal 11 is
transferred via the path over signal lines 11 - 13 - 19 back to the isolated transmission
means 16.
[0041] The interface 8 of the embodiment may be adapted for every kind of present or future
dimming protocol without departing from the invention. The invention can be used in
any approach for a main controlling unit dimming (MCU dimming), for wireless dimming
protocols, in dimming protocols basing of pulse phase modulation for dimming signal
transfer, for analogue dimming signals as depicted in figs. 1 and 2 as well as for
digital dimming signals. Typical digital dimming signals may be compliant with a 1V-10V
signal according to norm IEC 60929, or a 0V to 10V signal compliant with standard
ANSI E1.3 - 2001 (R2006).
[0042] The further isolated transmission means 16 can be implemented as a current transformer.
A current transformer is a measurement device connected in series and designed to
provide a current signal in a secondary coil proportional to the current flowing in
its primary coil. A current transformer as an isolated transmission means 16 includes
a primary coil and secondary coil, the secondary coil also being referenced as detection
winding. The current transformer is basic, double or higher insulated, depending on
the application. The detection winding of the current transformer is for example connected
to the output winding of the flyback transformer as a power conversion stage, or to
a secondary winding of an LLC output. The detection winding may be one or more windings
and outputs the current signal which includes information reflecting the current output
by the isolated power converting stage.
[0043] Current transformers are commonly used for metering purposes and as protective relays.
The current transformer employed in the isolated transmission means 16 in the present
embodiment serves the purpose of galvanically isolating the secondary side 6 of the
power converting stage on one hand and the interface 8 on the other hand, while simultaneously
generating and outputting the current signal 19 to the interface control circuit 20
in the interface 8. The current signal indicates a current flow on the secondary side
6 of the power converter stage and carries information on the actual current value
provided via lines 15.1, 15.2 to the illuminant 14. The current signal is fed via
lines 21, 23 to an interface control circuit 20.
[0044] The interface 8 receives as external input a dimming signal via dimming input lines
17.1, 17.2 and feeds the dimming signal to the interface control circuit 20. The interface
control circuit 20 is also provided with the current signal via lines 21, 23. Thus
the interface control circuit 20 has the necessary signals available to generate a
control signal and supply the control signal via line 25 to a further isolated transmission
means 22.
[0045] The further isolated transmission means 22 provides the control signal to the power
conversion control circuit 24.
[0046] The arrangement of the further isolated transmission means 22 and the power conversion
control circuit 24 with respect to the galvanically isolated first and second substages
4, 6 denotes the key difference between the embodiment depicted in fig. 1 and the
embodiment depicted in fig. 2.
[0047] The power conversion control circuit 24 of fig. 1 controls the power conversion unit
12 such that current driving the illuminant 14 is controlled to a value suitable to
generate a desired light intensity to be emitted by the illuminant and indicated by
the dimming signal received via inputs 17.1, 17.2 by the dimmable converter.
[0048] If the power conversion unit 12 includes a buck converter, this is implemented by
the power conversion unit 12 controlling a switch S1 of the buck converter and thereby
setting an output current of the power conversion unit 12 accordingly.
[0049] The further isolated transmission means 22 is in an embodiment implemented by using
an optocoupler (photocoupler, optoisolator). An optocoupler is an optoelectric circuit
component that transfers electric signals between two isolated circuit by using light.
Optocouplers prevent the transfer of high voltages and thereby avoid affecting a system
receiving a signal by maintaining galvanic isolation between input and output of the
optocoupler.
[0050] A common type of an optocoupler consists of an LED as a source (emitter) of light
and a phototransistor in an opaque package. Usually an optocoupler transfers a digital
signal (ON/OFF), but some are capable to transfer an analogue signal. The LED, for
example a near infrared light-emitting diode, converts an electric input signal into
light, a closed optical channel (dielectrical channel) transfers the light to a photosensitive
element, the photosensitive element detects the incoming light and either generates
electric energy directly, or modulates an electric current flowing from an external
power supply by the received incoming light.
[0051] The power conversion control circuit 24' of fig. 2 also controls the power conversion
unit 12 such that current driving the illuminant 14 is controlled to a value suitable
to generate a desired light intensity to be emitted by the illuminant and indicated
by the dimming signal received via inputs 17.1, 17.2 by the dimmable converter. However
the power conversion control circuit 24' is arranged at the secondary side 6 of the
power conversion stage. Accordingly the further transmission means 22' for transferring
the control signal received in the interface 8 via line 25 transfers the control signal
to the secondary side 6 of the power conversion stage. The power conversion control
circuit 24' arranged on the secondary side 6 of the power conversion stage and the
power conversion unit 12' may be configured as a secondary side controlled power conversion
unit, contrary to the power conversion regulation in the shown in fig. 1.
[0052] Both variants of isolated transmission elements, transformers and optocouplers discussed
above are efficient in breaking ground loops caused by high or noisy return currents
in signal lines. The optocoupler is even suited to transfer DC signals or slowly varying
signals.
[0053] In an embodiment the control circuit 24, 24' of the isolated power converter stage
regulates the current flow to the illuminant 14 at a preset current value in a feedback
loop including at least a part of the primary side 4 of the isolated power converter
stage, when the control circuit 24, 24' receives no control signal from the interface
control circuit 20.
[0054] The interface control circuit 20 can be analog, a digital or a hybrid circuit. The
interface control circuit 20 is in one embodiment adapted to control the power regulation
loop to regulate the current to the illuminant 14. Another embodiment controls the
current to the illuminant by the control unit 24, 24'.
[0055] Fig. 3 shows an existing solution for the problem solved by present application and
starting from the existing solution of fig. 3, additional benefits of the invention
are discussed.
[0056] Generally for many applications in luminary design the converter requires either
SELV output or a double insulation from input to output. If a conventional LED converter
includes an interface which is directly connected to the output, meaning there is
no galvanic isolation between the interface receiving the dimming signal and the secondary
side of the power converting stage. If a basically insulated dimmer unit is connected
with such conventional dimmable converter, the entire luminary arrangement including
the conventional converter and the only basically insulated dimmer is also only basically
insulated. This luminary arrangement may result in a potential danger to a human being
coming into contact with the luminary.
[0057] The circuit design 28 depicted in fig. 3 offers a solution which is commonly used.
A transformer 30 with a fixed operating frequency receives power via a driver input
port 31 (X6-a) for communication between a dimmer unit which is not shown and the
dimmable LED converter 1 from dimming signal input ports 32 (X6-b, X6-c) to communication
ports 33 (X4-a and X4-b). However the circuit shown in fig. 3 suffers from a lack
of linearity of the dimming curve, as the RC filter introduces a distortion for transmitting
dimming levels which may vary over a large range.
[0058] The embodiments of the dimmable converter according to fig. 1 and fig. 2 however
dispense with respective RC-filter layout as shown in fig. 3 and therefore the inventive
dimmable converter layout offers good linearity over the dimming curve as an additional
advantage, while simultaneously double isolation or SELV-output of the dimmable converter
1 is achieved.
[0059] The approach according to embodiments of the invention is independent from the actual
general circuit topology used in the power converting stage. The approach is equally
applicable for converter types such as a half bridge converter, a LLC resonant converter,
a flyback converter, a forward converter, a buck converter, a boost converter, a buck-boost
converter or else.
[0060] All single features of the discussed embodiments described and illustrated in the
accompanying figures by way of example may also be combined in an appropriate and
advantageous manner without prejudice to the underlying principles of the invention
as defined in the appending claims.
1. A system comprising an illuminant (14) and a dimmable converter (1) for driving the
illuminant (14), the dimmable converter (1) comprising:
• a power conversion control unit (24, 24'),
• an isolated power conversion unit (12, 12') comprising a switch arranged on a primary
side of the isolated power conversion unit (12, 12'),
• a first transmission means (16),
• a second isolated transmission means (22),
• an interface control circuit (20),
• an output rectification and filter unit (10),
• wherein a primary side of the isolated power conversion unit (12, 12') is configured
to receive a direct current and is further configured to convert the direct current
into a first output current provided on a secondary side of the isolated power conversion
unit (12, 12') and is further configured to send the first output current to the output
rectification and filter unit (12),
• wherein the output rectification and filter unit (10) is configured to rectify and
filter the first output current, thereby arriving at a second output current, the
output rectification and filter unit (10) is further configured to send the second
output current to the illuminant (14), characterized in that
the first transmission means is an isolated transmission means and the output rectification
and filter unit (10) is further configured to send the first output current as an
input signal of the first isolated transmission means (16) to a primary side of the
first isolated transmission means (16) and,
• wherein the primary side of the first isolated transmission means (16) is configured
to receive the first output current from the output rectification and filter unit
(10) and the first isolated transmission means (16) is configured to convert the first
output current into a third output current provided on a secondary side of the first
isolated transmission means (16) and the primary side of the first isolated transmission
means (16) is further configured to send the first output current back to the secondary
side of the isolated power conversion unit (12,12'),
• wherein the interface control circuit (20) is configured to receive the third output
current, to receive a dimming signal and to generate a first control signal based
on the third output current and the dimming signal,
• wherein the second isolated transmission means (22) is configured to receive the
first control signal from the interface control circuit (20) and convert the first
control signal into a second control signal,
• wherein the power conversion control unit (24, 24') is configured to control a switching
of the switch based on the second control signal, thereby setting the first output
current to a value suitable to generate a desired light intensity to be emitted by
the illuminant (14) and indicated by the dimming signal.
2. The system according to claim 1,
characterized in
that the first and second isolated transmission means (16, 22, 22') include either a transformer
and/or an optocoupler.
3. The system according to claim 1,
characterized in that
the isolated power conversion unit (12, 12') comprises compensating means configured
to compensate non-linear characteristics of the optocoupler and/or aging effects of
the optocoupler.
4. The system according to any one of claims 1 to 3,
characterized in
that the second output current indicates a current flow on the secondary side of the isolated
power conversion unit (12, 12') for driving the illuminant (14).
1. System, aufweisend ein Leuchtmittel (14) und einen dimmbaren Wandler (1) zum Antreiben
des Leuchtmittels (14), wobei der dimmbare Wandler (1) Folgendes umfasst:
• eine Leistungswandlung-Steuereinheit (24, 24'),
• eine isolierte Leistungswandlungseinheit (12, 12'), einen Schalter umfassend, der
an einer primären Seite der isolierten Leistungswandlungseinheit (12, 12') angeordnet
ist,
• ein erstes Übertragungsmittel (16),
• ein zweites, isoliertes Übertragungsmittel (22),
• eine Schnittstellen-Steuerschaltung (20),
• eine Ausgangsgleichrichtungs- und -filtereinheit (10),
• wobei eine primäre Seite der isolierten Leistungswandlungseinheit (12, 12') dazu
ausgelegt ist, einen Gleichstrom zu empfangen, und ferner dazu ausgelegt ist, den
Gleichstrom in einen ersten Ausgangsstrom umzuwandeln, der an einer sekundären Seit
der isolierten Leistungswandlungseinheit (12, 12') bereitgestellt wird, und ferner
dazu ausgelegt ist, den ersten Ausgangsstrom an die Ausgangsgleichrichtungs- und -filtereinheit
(12) zu senden,
• wobei die Ausgangsgleichrichtungs- und -filtereinheit (10) dazu ausgelegt ist, den
ersten Ausgangsstrom gleichzurichten und zu filtern, wodurch ein zweiter Ausgangsstrom
entsteht, wobei die Ausgangsgleichrichtungs- und -filtereinheit (10) ferner dazu ausgelegt
ist, den zweiten Ausgangsstrom an das Leuchtmittel (14) zu senden, dadurch gekennzeichnet, dass das erste Lichtübertragungsmittel ein isoliertes Übertragungsmittel ist und die Ausgangsgleichrichtungs-
und -filtereinheit (10) ferner dazu ausgelegt ist, den ersten Ausgangsstrom als ein
Eingangssignal des ersten isolierten Übertragungsmittels (16) an eine primäre Seite
des ersten isolierten Übertragungsmittels (16) zu senden, und
• wobei die primäre Seite des ersten isolierten Übertragungsmittels (16) dazu ausgelegt
ist, den ersten Ausgangsstrom von der Ausgangsgleichrichtungs- und - filtereinheit
(10) zu empfangen, und das erste isolierte Übertragungsmittel (16) dazu ausgelegt
ist, den ersten Ausgangsstrom in einen dritten Ausgangsstrom umzuwandeln, der an einer
sekundären Seite des ersten isolierten Übertragungsmittels (16) bereitgestellt wird,
und die primäre Seite des ersten isolierten Übertragungsmittels (16) ferner dazu ausgelegt
ist, den ersten Ausgangsstrom zurück zu der sekundären Seite der isolierten Leistungswandlungseinheit
(12, 12') zu senden,
• wobei die Schnittstellen-Steuerschaltung (20) dazu ausgelegt ist, den dritten Ausgangsstrom
zu empfangen, ein Dimmsignal zu empfangen und ein erstes Steuersignal auf der Grundlage
des dritten Ausgangsstroms und des Dimmsignals zu erzeugen,
• wobei das zweite isolierte Übertragungsmittel (22) dazu ausgelegt ist, das erste
Steuersignal von der Schnittstellen-Steuerschaltung (20) zu empfangen und das erste
Steuersignal in ein zweites Steuersignal umzuwandeln,
• wobei die Leistungswandlung-Steuereinheit (24, 24') dazu ausgelegt ist, ein Schalten
des Schalters auf der Grundlage des zweiten Steuersignals zu steuern, wodurch der
erste Ausgangsstrom auf einen Wert eingestellt wird, der geeignet ist, um eine gewünschte
Lichtintensität zu erzeugen, die durch das Leuchtmittel (14) zu emittieren ist und
von dem Dimmsignal angegeben wird.
2. System nach Anspruch 1,
dadurch gekennzeichnet, dass
das erste und das zweite isolierte Übertragungsmittel (16, 22, 22') entweder einen
Transformator und/oder einen Optokoppler beinhalten.
3. System nach Anspruch 1,
dadurch gekennzeichnet, dass
die isolierte Leistungswandlungseinheit (12, 12') Ausgleichsmittel umfasst, die dazu
ausgelegt sind, nicht-lineare Charakteristiken des Optokopplers und/oder Alterungseffekte
des Optokopplers auszugleichen.
4. System nach einem der Ansprüche 1 bis 3,
dadurch gekennzeichnet, dass
der zweite Ausgangsstrom einen Stromfluss an der sekundären Seite der isolierten Leistungswandlungseinheit
(12, 12') zum Antreiben des Leuchtmittels (14) angibt.
1. Système comprenant un élément d'éclairage (14) et un convertisseur à gradation (1)
pour piloter l'élément d'éclairage (14), le convertisseur à gradation (1) comprenant
:
• une unité de commande de conversion de puissance (24, 24') ;
• une unité de conversion de puissance isolée (12, 12') comprenant un commutateur
agencé sur un côté primaire de l'unité de conversion de puissance isolée (12, 12')
;
• un premier moyen de transmission (16) ;
• un second moyen de transmission isolé (22) ;
• un circuit de commande d'interface (20) ;
• une unité de filtrage et de redressement de sortie (10) ;
• dans lequel un côté primaire de l'unité de conversion de puissance isolée (12, 12')
est configuré de manière à recevoir un courant continu, et est en outre configuré
de manière à convertir le courant continu en un premier courant de sortie fourni sur
un côté secondaire de l'unité de conversion de puissance isolée (12, 12'), et est
en outre configuré de manière à envoyer le premier courant de sortie à l'unité de
filtrage et de redressement de sortie (12) ;
• dans lequel l'unité de filtrage et de redressement de sortie (10) est configurée
de manière à redresser et filtrer le premier courant de sortie, ce qui permet par
conséquent d'obtenir un deuxième courant de sortie, et l'unité de filtrage et de redressement
de sortie (10) est en outre configurée de manière à envoyer le deuxième courant de
sortie à l'élément d'éclairage (14), caractérisé en ce que :
le premier moyen de transmission est un moyen de transmission isolé et l'unité de
filtrage et de redressement de sortie (10) est en outre configurée de manière à envoyer
le premier courant de sortie, sous la forme d'un signal d'entrée du premier moyen
de transmission isolé (16), à un côté primaire du premier moyen de transmission isolé
(16) ;
• dans lequel le côté primaire du premier moyen de transmission isolé (16) est configuré
de manière à recevoir le premier courant de sortie en provenance de l'unité de filtrage
et de redressement de sortie (10), et le premier moyen de transmission isolé (16)
est configuré de manière à convertir le premier courant de sortie en un troisième
courant de sortie fourni sur un côté secondaire du premier moyen de transmission isolé
(16), et le côté primaire du premier moyen de transmission isolé (16) est en outre
configuré de manière à renvoyer le premier courant de sortie au côté secondaire de
l'unité de conversion de puissance isolée (12, 12') ;
• dans lequel le circuit de commande d'interface (20) est configuré de manière à recevoir
le troisième courant de sortie, à recevoir un signal de gradation, et à générer un
premier signal de commande sur la base du troisième courant de sortie et du signal
de gradation ;
• dans lequel le second moyen de transmission isolé (22) est configuré de manière
à recevoir le premier signal de commande en provenance du circuit de commande d'interface
(20) et à convertir le premier signal de commande en un second signal de commande
; et
• dans lequel l'unité de commande de conversion de puissance (24, 24') est configurée
de manière à commander une commutation du commutateur sur la base du second signal
de commande, ce qui permet de régler par conséquent le premier courant de sortie sur
une valeur appropriée pour générer une intensité lumineuse souhaitée devant être émise
par l'élément d'éclairage (14) et indiquée par le signal de gradation.
2. Système selon la revendication 1,
caractérisé en ce que
les premier et second moyens de transmission isolés (16, 22, 22') incluent un transformateur
et/ou un optocoupleur.
3. Système selon la revendication 1,
caractérisé en ce que
l'unité de conversion de puissance isolée (12, 12') comprend un moyen de compensation
configuré de manière à compenser des caractéristiques non linéaires de l'optocoupleur
et/ou des effets de vieillissement de l'optocoupleur.
4. Système selon l'une quelconque des revendications 1 à 3,
caractérisé en ce que
le deuxième courant de sortie indique un flux de courant sur le côté secondaire de
l'unité de conversion de puissance isolée (12, 12') pour piloter l'élément d'éclairage
(14).