DE202017100069U1 - Dimmable LED drive circuit with passive bleeder resistor to stabilize dimming operation and improve power factor - Google Patents

Abstract

A dimmable LED drive circuit having a passive bleeder resistor for stabilizing dimming operation and improving power factor, comprising: a dimming circuit (100) for performing phase cutting operation of an AC voltage to provide a phase cut AC voltage in response to a dimming input ; a bridge rectifier (110) that provides an input voltage by performing a rectifying operation of the phase-cut AC voltage; a passive leakage resistance circuit (120) connected between the input voltage and a ground and comprising a charge path, a discharge path and a capacitor, the charge path having a series connection of a diode (121) and a first resistor (122), the discharge path a second Resistor (124), the charge path and the discharge path form a parallel connection path, wherein the parallel connection network is connected in series with the capacitor (123) and the second resistor (124) has a resistance which is greater than that of the first capacitor (122) ; and a power converter (130) for converting the input voltage to an output current for an LED load (240).

Description

BACKGROUND OF THE INVENTION

Technical environment

The present invention relates to a dimmable LED driving circuit (light emitting diode), more particularly to a dimmable LED driving circuit having a passive leakage resistance capable of stabilizing a dimming operation and maintaining a good power factor.

State of the art

Dimmable lighting circuits according to the prior art are operated with a triac-based dimmer to perform a phase intersection operation with a standard AC power source (60 Hz / 110 V in North America or 50 Hz / 220 V in Europe) in response to a dimming operation and thus controlling the input power and thus the lighting conditions of a traditional lamp.

Because of longer life and better electrical efficiency, traditional lamps have been increasingly replaced by LED lamps. In addition to maintaining a good power factor, in applications where a traditional lamp is replaced with an LED lamp, the driving circuit for the LED lamp must generally provide a constant output current to ensure stable lighting conditions. To meet these requirements, a switching mode LED drive circuit is generally designed to have a PFC (Power Factor Correction) function and a constant output current control mechanism, i. the LED driving circuit with the switching mode for driving the LED lamp is generally designed to provide an inversion of an in-phase input switching current with an input voltage while conducting a constant output current to an LED lamp.

The 1 shows a circuit diagram of a dimmable switching mode with the LED drive circuit according to the prior art. Like in the 1 As shown, the dimmable switching mode with the LED driving circuit driven by an AC voltage V _AC includes a triac-based dimmer 10 , a bridge rectifier 20 , a passive leakage resistance circuit 30 , a switching power converter 40 and an LED load 50 where the triac-based dimmer 10 from a TRIAC (not shown in the drawing) and the passive leakage resistance circuit 30 from one with a capacitor 32 series-connected resistance 31 consists.

When the triac-based dimmer triggers 10 at a phase angle of a half wave (positive half wave or negative half wave) of the _AC voltage V _AC becomes the capacitor 32 through the resistance 31 is charged to provide an auxiliary current set higher than a minimum hold current of the TRIAC to ensure a pass state of the TRIAC (it is known that the TRIAC is not in a pass state when the current flowing through the TRIAC is lower than the minimum hold current is). To meet this purpose, the capacitance of the capacitor must be 32 be big enough while the resistance 31 must be low. With a large capacity of the capacitor 32 and a low resistance 31 however, this significantly affects the power factor of the LED driving circuit. On the other hand, if the capacitor 32 on a low capacity and / or resistance 31 is set to a high resistance, the auxiliary current may be too low to ensure the on-state of the TRIAC.

To obviate the above drawbacks, the present invention is intended to provide a novel dimmable switching operation with an LED driving circuit.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a dimmable LED drive circuit that operates with a passive bleeder resistor to maintain both a stable dimming operation and simultaneously achieve a good power factor.

Another object of the present invention is to provide a dimmable LED driver circuit which is operated with a passive bleeder resistor to separately form a sinking current path and a feeding current path to maintain a good power factor and simultaneously ensure a holding current for a dimming circuit.

Yet another object of the present invention is to provide a dimmable LED drive circuit that operates with a passive bleeder resistor and has a simple and robust circuit for correspondingly adjusting the input current in a dimming operation.

To achieve the above objects, a dimmable LED drive circuit having a passive bleeder resistor for stabilizing dimming operation and improving the power factor is proposed, including:
A dimming circuit for performing a phase-cutting operation of an AC voltage to provide a phase-cutting AC voltage in response to a dimming input;
Bridge rectifier that provides an input voltage by performing rectifying operation on the phase-cut AC voltage;
passive leakage resistance circuit connected between the input voltage and a ground terminal, including a charge path, a discharge path, and a capacitor; the charging path comprises a series connection of a diode and a first resistor; the discharge path comprises a second resistor; forming, with the charging path and the discharging path, a parallel connection network, this parallel connection network being in series with the capacitor and the second resistor having a resistance greater than that of the first resistor; and
a power converter for converting the input voltage into an output current for an LED load.

In one embodiment, the dimming circuit is a TRIAC.

In one embodiment, the phase-cutting operation is a phase-cutting operation or a phase-cutting operation.

In one embodiment, a switching power converter is used as a power converter.

In one embodiment, a full-wave rectifier is used as the bridge rectifier.

In order to achieve the above-mentioned objects, there is proposed another dimmable LED driving circuit with passive leakage resistance for stabilizing the dimming operation and improving the power factor, which consists of the following components:
a dimming circuit for performing phase-cutting operation of an AC voltage to provide a phase-cut AC voltage in response to a dimming input;
a bridge rectifier providing an input voltage for performing rectifying operation on the phase-cut AC voltage;
a passive leakage resistance circuit connected between the input voltage and a ground terminal, including a charge path, a discharge path, and a capacitor; the charging path comprises a series connection of a diode and a first resistor; the discharge path comprises a second resistor and a second resistor; forming, with the charging path and the discharging path, a parallel connection network, this parallel connection network being in series with the capacitor, the second resistor having a resistance greater than that of the first resistor; and
a power converter for converting the input voltage into an output current for an LED load.

For a better understanding of the object of the present invention, its structure, novel features and performance will be more readily apparent from preferred embodiments with reference to the accompanying drawings for the detailed description of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 illustrates a circuit diagram of a prior art dimmable dimming switching mode LED driving circuit. FIG.

2 FIG. 12 illustrates a circuit diagram of a dimmable LED drive circuit according to an embodiment of the present invention. FIG.

3a - 3b illustrates the waveforms of the operation of the present invention as compared to the prior art circuit at two different dimming settings.

4 FIG. 12 illustrates a circuit diagram of a dimmable LED driving circuit according to another embodiment of the present invention.

WAYS TO CARRY OUT THE PREFERRED EMBODIMENTS

The 2 FIG. 12 illustrates a schematic diagram of a dimmable LED drive circuit according to one embodiment of the present invention 2 As shown, the dimmable LED drive circuit consists of a dimmer circuit 100 , a bridge rectifier 110 , a passive leakage circuit 120 , a power converter 130 and from an LED load 140 ,

With the dimmer circuit 100 In general, consisting of a TRIAC, a phase-cutting operation of an _AC voltage V _{AC is} performed to provide a phase-cut _AC voltage in response to a dimming input. This phase-cut operation may be a phase-cutting operation or a phase-cutting operation.

The bridge rectifier 110 That is, a full-wave rectifier is used for supplying an input voltage V _IN by performing a rectifying operation of the phase-cut AC voltage.

The passive leakage resistance circuit 120 , which is connected between the input voltage V _IN and a ground terminal, consists of a diode 121 , a first resistance 122 , a capacitor 123 and a second resistor 124 , The diode 121 and the first resistance 122 are connected in series to create a charging path. The second resistance 124 is used as a discharge path. The charging path and the discharge path form a parallel connection network, this parallel connection network with the capacitor 123 connected in series. In this embodiment, the diode 121 an anode connected to the input voltage V _IN , while a cathode connected to the first end of the first resistor 122 is coupled. One end of the capacitor 123 is with the second end of the first resistor 122 and the other end connected to the ground. An end to the second resistance 124 is with the anode and another end with the second end of the first resistor 122 connected, the second resistor 124 has a resistance greater than that of the first resistor 122 is.

To ensure that sufficient current through the TRIAC of the dimmer circuit 100 flows to get the lead of the TRIAC, the first resistor must 122 have a low resistance. To achieve a good power factor, the resistance of the second resistor must be 124 preferably be as large as possible. Is the resistance of the second resistor 124 but too big, the on the capacitor 123 At the end of the half-wave of the _AC voltage V _AC remaining loads cause the voltage of the capacitor 123 is higher than the voltage of the _AC voltage V _AC at a burning time of the TRIAC in a next half cycle, the TRIAC may not be activated in the next half cycle. In a scenario in which the _AC voltage V _{AC has} a frequency of 50 Hz, the time constant for the series connection of the second resistor is 124 and the capacitor 123 preferably about 3 ms, to maintain stable continuous operation while maintaining a good power factor.

It should also be noted that the positions of the parallel connection network (formed with the charging path and the discharge path) and the capacitor 123 can be exchanged, the positions of the diode 121 and the first resistance 122 are also interchangeable to achieve the same function of the present invention.

The power converter 130 is used to convert the input voltage V _IN into an output current I _OUT for the LED load 140 used.

The 3a - 3b In the operation of the present invention, the waveforms in operation of the present invention compare with the waveforms in the operation of a prior art circuit with two different dimming settings. As shown in the drawings, the input current of the present invention is more in phase with the input voltage than the input current of the prior art circuit, ie, the present invention achieves a better power factor than the prior art circuit.

Due to the principle described above, the 4 another embodiment of the dimmable LED drive circuit of the present invention. Like in the 4 As shown, the dimmable LED drive circuit consists of a dimming circuit 200 , a bridge rectifier 210 , a passive leakage circuit 220 , a power converter 230 and from an LED load 240 ,

With the dimmer circuit 200 In general, consisting of a TRIAC, a phase-cutting operation of an _AC voltage V _{AC is} performed to provide a phase-cut _AC voltage in response to a dimming input. The phase-cut operation may be a phase-cutting operation or a phase-cutting operation.

With the bridge rectifier 210 Operating as a full-wave rectifier, an input voltage V _{IN is provided} by performing a rectifying operation of the phase-cut AC voltage.

The passive leakage resistance circuit 220 Which is connected between the input voltage V _IN and a ground, consisting of a first diode 221 , a first resistance 222 , a capacitor 223 , a second resistor 224 and a second diode 225 , The first diode 221 and the first resistance 222 are connected in series to form a charge path, while the second diode 225 and the second resistance 224 connected in series to form a discharge path. With the charging path and the discharge path, a parallel connection network is formed, this parallel connection network with the capacitor 223 connected in series. In this embodiment, in the first diode 221 a first anode having the input voltage V _IN and a first cathode having a first end of the first resistor 222 coupled. One end of the capacitor 223 is with a second end of the first resistor 222 coupled while another end is connected to a ground. An end to the second resistance 224 is with the first anode and the other end with a second cathode of the second diode 225 while a second anode of the second diode 225 with the second end of the first resistor 222 connected and the second resistor 224 has a resistance greater than that of the first resistor 222 is.

With the power converter 230 the input voltage V _{IN is converted} into an output current I _OUT for the LED load 240 transformed.

In operation, the current path is connected to the series connection of the first diode 221 , the first resistance 222 and the capacitor 223 is created, ensuring that sufficient current through the triac of the dimmer circuit 200 flows to keep the TRIAC conductive, with the first resistor 222 has a low resistance to flow through a current that is greater than a minimum holding current of the TRIACs. With the current path, with the series connection of the second diode 225 and with the second resistor 224 is created, it ensures that a good power factor is achieved and at the same time the load on the capacitor 223 is stored, discharged to below a low level, the resistance of the second resistor 224 was selected correctly. For example, if the _AC voltage V _{AC has} a frequency of 50 Hz, the time constant for the second resistor is 224 and the capacitor 223 preferably about 3 ms.

It should also be noted that the positions of the parallel connection network (formed with the charging path and the discharge path) and the capacitor 223 are interchangeable, the positions of the first diode 221 and the first resistance 222 can be exchanged while the positions of the second diode 225 and the second resistor 224 are also interchangeable to achieve the same function of the present invention.

• 1. Mit der dimmbaren LED-Ansteuerungsschaltung der vorliegenden Erfindung kann ein passiver Ableitwiderstand zum gleichzeitigen Aufrechterhalten eines stabilen Dimmbetriebs und eines guten Leistungsfaktors verwendet werden.
• 2. Die dimmbare LED-Ansteuerungsschaltung der vorliegenden Erfindung kann einen passiven Ableitwiderstand verwenden, um separat einen phasenanschneidenden oder ein phasenabschneidender Betrieb zu liefern uns somit einen guten Leistungsfaktor aufrechtzuerhalten, während ein Haltestrom für einen Dimmerkreis sichergestellt wird.
• 3. Der dimmbare LED-Ansteuerungsschaltung der vorliegenden Erfindung verwendet einen passiven Ableitwiderstand, um einen einfachen und robusten Kontrollmechanismus zum angemessenen Einstellen des Eingangsstroms während einem Dimmbetrieb zu schaffen.

Thanks to the above-described designs, the present invention is characterized by the following advantages as follows:

• 1. With the dimmable LED driving circuit of the present invention, a passive leakage resistance for simultaneously maintaining a stable dimming operation and a good power factor can be used.
• 2. The dimmable LED drive circuit of the present invention can use a passive bleeder resistor to separately provide phase-cutting or phase-cutting operation, thus maintaining good power factor while ensuring a holding current for a dimming circuit.
• 3. The dimmable LED drive circuit of the present invention uses a passive bleeder resistor to provide a simple and robust control mechanism for properly adjusting the input current during a dimming operation.

Despite the description of the present invention by way of examples and preferred embodiments, it is to be understood that the present invention is not limited thereto. Rather, various modifications, similar arrangements and procedures are intended to be included so that the scope of the appended claims is to be accorded the widest scope so as to encompass all such modifications, similar arrangements and procedures.

In summary of the above description, the present invention improves the performance in comparison with the prior art structure, and the present invention also satisfies the requirements of the patent application so that it can be used by the Patent and Trademark Office for review and assessment Grant of the relevant patent rights.

Claims (10)

A dimmable LED drive circuit with a passive bleeder resistor to stabilize dimming operation and to improve the power factor, consisting of: a dimming circuit ( 100 ) for performing phase cutting operation of an AC voltage to provide a phase cut AC voltage in response to a dimming input; a bridge rectifier ( 110 ) which provides an input voltage by performing a rectifying operation of the phase-cut AC voltage; a passive leakage resistance circuit ( 120 ), which is connected between the input voltage and a ground and comprises a charging path, a discharge path and a capacitor, wherein the charging path is a series connection of a diode ( 121 ) and a first resistor ( 122 ), the discharge path has a second resistor ( 124 ), the charging path and the discharge path form a parallel connection path, wherein the parallel connection network with the capacitor ( 123 ) is connected in series and the second resistor ( 124 ) has a resistance greater than that of the first capacitor ( 122 ); and a power converter ( 130 ) for converting the input voltage into an output current for an LED load ( 240 ). The dimmable LED drive circuit having a passive bleeder resistor for stabilizing the dimming operation and improving the power factor of claim 1, wherein the dimming circuit ( 100 ) consists of a TRIAC. The dimmable LED drive circuit having a passive bleeder resistor for stabilizing the dimming operation and improving the power factor of claim 1, wherein the phase cutting operation is a phase-cutting operation or a phase-cutting operation. The dimmable LED drive circuit with a passive bleeder resistor for stabilizing the dimming operation and for improving the power factor according to claim 1, wherein as a power converter ( 130 ) a switching power converter is used. The dimmable LED drive circuit with a passive bleeder resistor for stabilizing the dimming operation and improving the power factor according to claim 1, wherein as a bridge rectifier ( 110 ) a full-wave rectifier is used. The dimmable LED drive circuit with a passive bleeder resistor for stabilizing the dimming operation and improving the power factor, comprising: a dimming circuit ( 200 ) for performing phase cutting operation of an AC voltage to provide a phase cut AC voltage in response to a dimming input; a bridge rectifier ( 210 ), by which an input voltage is supplied by performing a rectifying operation of the phase-cut AC voltage; a passive leakage resistance circuit ( 220 ) connected between the input voltage and a ground, including a charge path, a discharge path, and a capacitor ( 223 ); the charging path is a series connection of a first diode ( 221 ) and a first resistance ( 122 ); the discharge path is a second diode ( 225 ) and a second resistor ( 224 ); the charging path and the discharge path form a parallel connection network, this parallel connection network with the capacitor ( 223 ) is connected in series; the second resistor ( 224 ) has a resistance greater than that of the first resistor ( 222 ); and a power converter ( 230 ) for converting the input voltage into an output current for an LED load ( 240 ). The dimmable LED drive circuit having a passive bleeder resistor for stabilizing the dimming operation and improving the power factor of claim 6, wherein the dimming circuit ( 200 ) consists of a TRIAC. The dimmable LED drive circuit having a passive bleeder resistor for stabilizing the dimming operation and improving the power factor of claim 6, wherein the phase cutting operation is a phase-cutting operation or a phase-cutting operation. The dimmable LED drive circuit having a passive bleeder resistor for stabilizing the dimming operation and improving the power factor according to claim 6, wherein as a power converter ( 230 ) a switching power converter is used. The dimmable LED drive circuit with a passive bleeder resistor for stabilizing the dimming operation and for improving the power factor according to claim 6, wherein as a bridge rectifier ( 210 ) a full-wave rectifier is used.

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