CN117279153A - Light modulator compatible LED driving circuit, driving method and lighting system - Google Patents

Light modulator compatible LED driving circuit, driving method and lighting system Download PDF

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Publication number
CN117279153A
CN117279153A CN202311066517.6A CN202311066517A CN117279153A CN 117279153 A CN117279153 A CN 117279153A CN 202311066517 A CN202311066517 A CN 202311066517A CN 117279153 A CN117279153 A CN 117279153A
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China
Prior art keywords
circuit
power conversion
signal
led
conversion circuit
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CN202311066517.6A
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Chinese (zh)
Inventor
刘国强
何颖彦
黄必亮
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Joulwatt Technology Co Ltd
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Joulwatt Technology Co Ltd
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Priority to CN202311066517.6A priority Critical patent/CN117279153A/en
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    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/395—Linear regulators
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/355—Power factor correction [PFC]; Reactive power compensation
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/375—Switched mode power supply [SMPS] using buck topology
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits

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  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

The application discloses a light modulator compatible LED driving circuit, a driving method and a lighting system, wherein a switch control circuit detects whether the LED driving circuit needs light modulation, and in a non-light modulation state, the switch control circuit controls the power conversion circuit to perform power conversion according to a current detection signal of a linear control circuit; and in the dimming state, the switch control circuit controls the switch state of the controllable switch tube according to the output feedback signal of the power conversion circuit. The control power conversion circuit has the advantages that under the non-dimming condition, the output voltage of the control power conversion circuit is close to the voltage drop of the LED and the linear control circuit, the loss of the system is low, and the overall efficiency is high; in the dimming state, the input current of the power conversion circuit is controlled to work in a wider range, so that the system compatibility is good. The LED driving circuit system has good overall application adaptability.

Description

Light modulator compatible LED driving circuit, driving method and lighting system
Technical Field
The present invention relates to the field of power electronics, and more particularly, to a driving circuit, a driving method, and a lighting system for an LED compatible with a dimmer.
Background
The LED is used as a novel energy-saving illumination light source, has the advantages of small volume and long service life, and is a main stream light source in the current market. Since the brightness of an LED is related to the current flowing therethrough, in an LED driving circuit, it is necessary to control the current flowing therethrough to be constant in order to maintain a stable operation current thereof. As shown in fig. 1, an input voltage is received through a switch-type power conversion circuit, and is rectified to perform power conversion, a proper output voltage Vo is output to drive an LED, and a constant current is output to maintain the brightness of the LED stable.
However, in the case of LED lighting that requires compatible dimming in the european and american market, the power correction factor PF of the lighting system is required to reach 0.9, according to the standard requirements of europe and america: in applications without dimming, the lighting system is required to meet high efficiency (e.g., efficiency up to 94% or more) and no strobe requirements; in the application occasions with dimming, the requirement of high PF needs to be met, and the driving circuit cannot meet the requirement of high efficiency and high PF at the same time.
Accordingly, there is a need to provide an improved solution to overcome the above technical problems in the prior art.
Disclosure of Invention
Accordingly, the present invention is directed to an LED driving circuit, driving method and lighting system compatible with a dimmer, which are used for solving the technical problem that the LED driving circuit in the prior art cannot meet both high efficiency and high PF.
A LED driving circuit compatible with a dimmer comprises a rectification circuit, a first switching circuit and a second switching circuit, wherein the rectification circuit receives an alternating current input signal and outputs a rectified signal subjected to rectification; the power conversion circuit comprises a controllable switch tube, the input end of the controllable switch tube is coupled to the rectifying circuit, and the output end of the controllable switch tube is coupled to the LED load; the switch control circuit is used for providing a switch control signal to control the switch state of the controllable switch tube, and the controllable switch tube executes on-off operation according to the switch control signal so as to control the output voltage of the output end of the power conversion circuit; a linear control circuit connected between a negative terminal of the LED load and a reference ground to control a current flowing through the LED load such that an operating current of the LED load is maintained stable; in a non-dimming state, the switch control circuit controls whether the power conversion circuit performs power conversion or not according to a current detection signal of the linear control circuit; and in the dimming state, the switch control circuit controls the switch state of the controllable switch tube according to the output feedback signal of the power conversion circuit.
Preferably, the switch control circuit controls the power conversion circuit to perform power conversion when the current detection signal is lower than a reference current.
Preferably, the switch control circuit includes a trigger signal generating circuit, the trigger signal generating circuit obtains a trigger signal according to the current detection signal, and when the trigger signal is in an active state, the switch control circuit controls the power conversion circuit to perform power conversion; when the trigger signal is in an invalid state, the switch control circuit controls the power conversion circuit to stop power conversion.
Preferably, the linear control circuit comprises a first switching tube, a first resistor connected in series with the first switching tube, and an error circuit, wherein one power end of the first switching tube is connected with the negative end of the LED load, the error circuit obtains a third feedback voltage according to sampling signals of connection nodes of the first switching tube and the first resistor, and error amplification is carried out on the third feedback voltage and a third reference voltage so as to control the switching state of the first switching tube, so that the working current of the LED load is maintained at a desired value; the trigger signal generating circuit detects the first switching tube and a first resistor connecting node to obtain the current detection signal, or the trigger signal generating circuit detects the grid voltage of the first switching tube to obtain the current detection signal.
Preferably, the switch control circuit includes a feedback circuit, and when the trigger signal is in an active state, the feedback circuit controls the power conversion circuit to perform power conversion according to an output feedback signal of the power conversion circuit and a first reference signal.
Preferably, when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the output end of the power conversion circuit, the first reference signal is set to be larger than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, and when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the negative end of the LED load, the first reference signal is set to be larger than the conduction voltage drop of the linear circuit, wherein the conduction voltage drop of the linear circuit is the product of the conduction resistance of the linear control circuit and the expected working current of the LED load.
Preferably, in the dimming state, the feedback circuit controls the switching state of the controllable switching tube according to the output feedback signal of the power conversion circuit and a second reference signal, when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the output end of the power conversion circuit, the second reference signal is set to be larger than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, and when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the negative end of the LED load, the second reference signal is set to be larger than the conduction voltage drop of the linear circuit, wherein the conduction voltage drop of the linear circuit is the product of the conduction resistance of the linear control circuit and the expected working current of the LED load.
Preferably, when the second reference signal is set to be greater than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, the difference between the second reference signal and the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit is any value between 50 and 150V, and when the second reference signal is set to be greater than the conduction voltage drop of the linear circuit, the difference between the second reference signal and the conduction voltage drop of the linear circuit is any value between 50 and 150V.
Preferably, the second reference signal setting is identical to the first reference signal size.
Preferably, the switch control circuit further comprises a dimming detection circuit, the dimming detection circuit detects the node voltage of the input end or the output end of the rectifying circuit to judge whether a dimmer exists, and when the dimmer exists, the switch control circuit controls the LED driving circuit to enter a dimming state; when the dimmer is not present, the switch control circuit controls the LED drive circuit to enter a non-dimming state.
Preferably, the switch control circuit further includes a logic circuit that receives output signals of the trigger signal generation circuit and the feedback circuit to generate the switch control signal.
Preferably, the power conversion circuit comprises an input capacitor, a Boost conversion circuit and an output capacitor, wherein the input capacitor is connected between the output end of the rectifying circuit and the input end of the Boost conversion circuit, the output end of the Boost converter is connected with the positive end of the LED load through the output capacitor, and the controllable switch tube is a main power switch tube of the Boost conversion circuit.
Preferably, at least part of the LED driving circuitry is integrated in one or more integrated chips.
In a second aspect, a driving method of an LED compatible with a dimmer is provided, the driving method is implemented by using the LED driving circuit, and the driving method of the LED includes the steps of: detecting whether a dimmer exists between the connecting end of the alternating current input signal and the rectifying circuit, controlling the LED driving circuit to work in a non-dimming state or a dimming state according to a detection result, and controlling the power conversion circuit to perform power conversion according to a current detection signal of the linear control circuit in the non-dimming state; in the dimming state, controlling the switching state of the controllable switching tube according to an output feedback signal of the power conversion circuit; the current flowing through the LED load is controlled so that the working current of the LED load is kept stable.
Preferably, when the current detection signal representing the current of the linear control circuit is lower than the reference current, a trigger signal in an active state is generated, when the trigger signal is in the active state, the power conversion circuit is controlled to perform power conversion, and when the trigger signal is in an inactive state, the power conversion circuit is controlled to stop power conversion, wherein the reference current is set to be a desired operating current of the LED load.
Preferably, the output voltage of the power conversion circuit in the dimming state is greater than the output voltage of the power conversion circuit in the non-dimming state.
Preferably, in the dimming state, the output voltage of the output end of the power conversion circuit is controlled to be a preset voltage, so that the magnitude of the input current of the power conversion circuit is equal to or greater than a first threshold current, wherein the magnitude of the first threshold current is set to enable the power factor of the LED driving circuit to at least reach 0.7.
In a third aspect, a lighting system is provided, comprising an LED load and the above-described LED driving circuit.
Preferably, the voltage drop of the LED load is configured such that the absolute value of the difference between the voltage drop of the LED load and the peak value of the ac input signal is within a preset voltage range, the preset voltage range being any value between 0 and 10V.
By adopting the control scheme of the LED driving circuit, the switch control circuit detects whether the LED driving circuit needs dimming or not, and in a non-dimming state, the switch control circuit obtains a trigger signal according to a feedback signal of the linear control circuit and then controls the power conversion circuit to perform power conversion or not according to the trigger signal; and in the dimming state, the switch control circuit controls the switch state of the controllable switch tube according to the output feedback signal of the power conversion circuit. The voltage drop of the system is low under the non-dimming condition, and the overall efficiency is high; in the dimming state, the input current of the power conversion circuit is controlled to work in a wider range, so that the system compatibility is good. The LED driving circuit system has good overall application adaptability.
Drawings
FIG. 1 is a circuit diagram of circuitry of a prior art LED driver circuit;
FIG. 2 is a circuit block diagram of a first embodiment of an LED driver circuit according to the present invention;
FIG. 3 is a specific circuit diagram of the linear control circuit of FIG. 2 according to the present invention;
FIG. 4 is a circuit block diagram of the switch control circuit of FIG. 2 according to the present invention;
FIG. 5 is a circuit diagram of the power conversion circuit of FIG. 2 according to the present invention;
FIG. 6 is a circuit diagram of a first implementation of the switch control circuit of FIG. 3 according to the present invention;
fig. 7 is a circuit diagram of a second implementation of the switch control circuit of fig. 3 according to the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments only. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention.
In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate and clearly illustrate the embodiments of the present invention.
Referring to fig. 2, which is a circuit block diagram of a first embodiment of an LED driving circuit according to the present invention, fig. 3 is a specific circuit diagram of the linear control circuit of fig. 2 according to the present invention; fig. 4 is a circuit diagram of the switch control circuit of fig. 2 according to the present invention, and fig. 5 is a circuit diagram of a first implementation of the power conversion circuit of fig. 2 according to the present invention. The LED driving circuit of the present embodiment includes a rectifying circuit, a power conversion circuit, a switching control circuit, and a linear control circuit, the rectifying circuit receiving an ac input signal V AC Outputting a rectified signal subjected to rectification processing; the power conversion circuit comprises a controllable switch tube, an input end of the power conversion circuit is coupled to the rectifying circuit, an output end of the power conversion circuit is coupled to an LED load, and particularly referring to FIG. 5, the power conversion circuit comprises an input capacitor C0, a Boost conversion circuit and an outputAnd the output capacitor C1 is connected between the output end of the rectifying circuit and the input end of the Boost conversion circuit, the controllable switch tube is a main power switch Guan Ru Q1 of the Boost conversion circuit, and the output capacitor C1 is connected between the output end of the Boost conversion circuit and the LED load. The switch control circuit provides a switch control signal V Q1 The linear control circuit is connected between the negative end of the LED load and the reference ground to control the current flowing through the LED load, so that the working current of the LED load is kept stable. In this example, the switch control circuit detects whether a dimmer exists between the connection end of the ac input signal and the rectifying circuit, and when the dimmer does not exist, the LED driving circuit enters a non-dimming state; when a dimmer is present, the LED drive circuit enters a dimming state.
Here, in the non-dimming state, the switch control circuit controls whether the power conversion circuit performs power conversion according to a current detection signal of the linear control circuit, preferably, the switch control circuit obtains a trigger signal according to the current detection signal, and then controls whether the power conversion circuit performs power conversion according to the trigger signal; when the trigger signal is in an effective state, the switch control circuit controls the power conversion circuit to perform power conversion; the switching control circuit controls the power conversion circuit to stop power conversion when the trigger signal is in an inactive state, and the trigger signal generation circuit outputs the trigger signal in an active state when the current detection signal is lower than a reference current, where the reference current is set to coincide with a desired operation current of the LED load.
And in the dimming state, the switch control circuit controls the switch state of the controllable switch tube according to the output feedback signal of the power conversion circuit. At this time, the trigger signal does not act on the power conversion circuit.
By the control mode, the output utilization of the power conversion circuit is maximized in the non-dimming state, the output voltage is provided for the LED load and the linear control circuit, the current demand of the linear control circuit can be just met, extra redundant voltage can not be generated, and the efficiency is very high. In the dimming state, the output of the power conversion circuit is controlled by outputting the feedback signal, so that the output of the power conversion circuit can meet the set output requirement.
As shown in fig. 3 or fig. 4, the linear control circuit includes a first switching tube Q2, a first resistor Rs connected in series with the first switching tube, one power end of the first switching tube is connected with the negative end of the LED load, and an error circuit obtains a third feedback voltage V according to a sampling signal of a connection node of the first switching tube and the first resistor FB3 And performing error amplification on the third feedback voltage and a third reference voltage Vref3 to control the switching state of the first switching tube, so that the working current of the LED load is maintained at a desired value. The third reference voltage Vref3 is set to a voltage value corresponding to an expected operating current of the LED load, so as to meet the power or current requirement. The first switching transistor Q2 may be a MOS transistor.
As shown in fig. 4, the switch control circuit includes a trigger signal generation circuit that detects a current of the linear control circuit to obtain a current detection signal that characterizes the same, a feedback circuit, and a logic circuit. As shown in fig. 6 and fig. 7, the trigger signal generating circuit detects the first switching tube and the first resistor connection node, for example, a point a, to obtain the current detection signal, or the trigger signal generating circuit detects the gate voltage of the first switching tube, for example, a point B, to obtain the current detection signal, where the voltage at the point a is in a proportional relationship with the current of the linear control circuit, and the voltage at the point B is in a proportional relationship with the current of the linear control circuit, which can both characterize the magnitude of the current of the linear control circuit.
With continued reference to FIG. 6, the feedback circuit includes a first error circuit that receives the output feedback signal of the power conversion circuit and a first reference signal to obtain a first error signal Vc1, a first comparison circuit, and an RS flip-flopA circuit for comparing the first error signal Vc1 with the inductor current sampling signal Vs of the power conversion circuit to generate the switch control signal V Q1’ . As shown in fig. 6, the switch control circuit obtains the output feedback signal of the power conversion circuit according to the output end of the power conversion circuit, and at this time, the first reference signal is set to be greater than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit. The first reference signal may be set to be slightly larger than the sum of the two voltage drops, or may be set to be far larger than the sum of the two voltage drops.
As shown in fig. 7, when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the negative terminal of the LED load, at this time, the first reference signal is set to be greater than the conduction voltage drop of the linear circuit, where the conduction voltage drop of the linear circuit is the product of the on-resistance of the linear control circuit and the desired operating current of the LED load. The first reference signal may be set to be slightly larger than the conduction voltage drop of the linear circuit, or may be set to be far larger than the conduction voltage drop of the linear circuit.
In the dimming state, the feedback circuit controls the switching state of the controllable switching tube according to the output feedback signal of the power conversion circuit and a second reference signal, and in this embodiment, the second reference signal is set to be consistent with the first reference signal in size. Thus, the feedback circuit in the dimmed state and the feedback circuit in the non-dimmed state are identical, and if the second reference signal is not identical in magnitude to the first reference signal, the feedback circuit may further comprise a second comparison circuit for comparing the output feedback signal with the second reference signal.
Similarly, referring to fig. 6, when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the output terminal of the power conversion circuit, the second reference signal is set to be greater than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, and referring to fig. 7, when the switch control circuit obtains the output feedback signal of the power conversion circuit according to the negative terminal of the LED load, the second reference signal is set to be greater than the conduction voltage drop of the linear circuit, wherein the conduction voltage drop of the linear circuit is the product of the conduction resistance of the linear control circuit and the expected operating current of the LED load.
Preferably, when the second reference signal is set to be greater than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, the difference between the second reference signal and the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit is any value between 50 and 150V, and when the second reference signal is set to be greater than the conduction voltage drop of the linear circuit, the difference between the second reference signal and the conduction voltage drop of the linear circuit is any value between 50 and 150V. The second reference signal is set to be higher in the dimming state, so that the output voltage of the power conversion circuit is preset voltage and is far higher than the voltage drop of the LED load and the conduction voltage drop of the linear circuit, the working range of the input current of the power conversion circuit is ensured to be wider in the dimming state, and the requirements of wide range and high PF are met.
Referring to fig. 3-7, the switch control circuit further includes a logic circuit that receives output signals of the trigger signal generation circuit and the feedback circuit to generate the switch control signal. Here, the logic circuit may include a driver that receives an initial switch control signal V Q1’ The trigger signal Vc can enable the driver to work or not work, or the logic circuit comprises an AND logic and the driver, and the trigger signal Vc and an initial switch control signal V Q1’ And performing AND computation, and obtaining the switch control signal after the computed signal passes through a driver.
With continued reference to fig. 3-5, the switch control circuit further includes a dimming detection circuit that detects a node voltage at an input or output of the rectifying circuit to determine whether a dimmer is present, and generates a determination result, such as V J When a dimmer exists, the switch control circuit controls the LED driving circuit to enter a dimming state; when the dimmer is not present, the switch control circuit controls the LED drive circuit to enter a non-dimming state. As shown in fig. 6 or 7, the judgment result can be transmitted to the comparison circuit of the trigger signal generation circuit to control the comparison circuit according to whether the dimmer existsIf the dimmer is present, the comparison result is not output, and the system enters a dimming state, if the dimmer is not present, the comparison result is output, and the system enters a non-dimming state.
When the current detection signal V is combined with FIG. 6 and FIG. 7 FB2 Less than the first reference signal V th1 The comparator circuit outputs a high level, the logic circuit is enabled at the high level, and the switch control signal V Q1 The state of the switch can be controlled to be active high. Those skilled in the art will recognize that the input of the comparator circuit can be adjusted, and the enable signal of the logic circuit can be adjusted accordingly, and the same functional effects can be obtained not only in the input state of fig. 6 or fig. 7.
Preferably, at least part of the LED driving circuitry is integrated in one or more integrated chips. Due to the adoption of the control scheme, the value of the input capacitor C0 is smaller, the volume and cost of the input capacitor are reduced, the input capacitor is convenient to integrate with other devices, and the scheme can achieve high integration; the application can also enable one integrated chip to be universal in dimming occasions and non-dimming occasions, and compared with the existing dimming occasions and non-dimming occasions which need different chips, the application greatly improves the applicability of the chips.
According to the LED driving circuit, in the non-dimming state, the output of the power conversion circuit is adjusted according to the current of a load, so that the output voltage of the power conversion circuit cannot have excessive surplus, the efficiency is very high, in the dimming state, the output voltage can be adjusted according to the adjustment of the input current so as to meet the wide input of the input current, the maintenance current of a dimmer is achieved as much as possible, the PF of the system is high, and the system is applicable to occasions with and without the dimmer by only using one chip, and the compatibility is very high.
The above embodiments take Boost topology as an example, and those skilled in the art will appreciate that in other embodiments, the power stage circuit may employ any suitable dc-dc topology, such as buck topology, boost topology, synchronous Boost topology, flyback, synchronous flyback, and other suitable topologies.
The application provides a driving method of an LED compatible with a dimmer, wherein the driving method is realized by using the LED driving circuit, and the driving method of the LED comprises the following steps: detecting whether a dimmer exists between the connecting end of the alternating current input signal and the rectifying circuit, controlling the LED driving circuit to work in a non-dimming state or a dimming state according to a detection result, and controlling the power conversion circuit to perform power conversion according to a current detection signal of the linear control circuit in the non-dimming state; in the dimming state, controlling the switching state of the controllable switching tube according to an output feedback signal of the power conversion circuit; the current flowing through the LED load is controlled so that the working current of the LED load is kept stable.
Preferably, when the current detection signal representing the current of the linear control circuit is lower than the reference current, a trigger signal in an active state is generated, when the trigger signal is in the active state, the power conversion circuit is controlled to perform power conversion, and when the trigger signal is in an inactive state, the power conversion circuit is controlled to stop power conversion, wherein the reference current is set to be a desired working current which is responsible for the LED.
Preferably, the output voltage of the power conversion circuit in the dimming state is greater than the output voltage of the power conversion circuit in the non-dimming state.
Preferably, in the dimming state, the output voltage of the output end of the power conversion circuit is controlled to be a preset voltage, so that the magnitude of the input current of the power conversion circuit is equal to or greater than a first threshold current, wherein the magnitude of the first threshold current is set to enable the power factor of the LED driving circuit to at least reach 0.7.
Finally, the application also provides a lighting system comprising the LED load and the LED driving circuit. Preferably, the voltage drop of the LED load is configured such that the absolute value of the difference between the voltage drop of the LED load and the peak value of the ac input signal is within a preset voltage range, the preset voltage range being any value between 0 and 10V. Here, by setting the voltage drop of the LED load to be close to the peak value of the ac input signal, in the non-dimming occasion, the controllable switching tube of the power conversion circuit can work in the off state as much as possible, the power consumption of the power conversion circuit can be ignored, the efficiency is high, and the efficiency can be well satisfied in the low-power requirement, and the maximization of the efficiency is achieved.
It should be noted that the detailed description and the corresponding drawings are merely illustrative of one way of implementing the method of the invention and are not limiting of the specific structure of the embodiments of the invention, and many changes or modifications may be made to these embodiments without departing from the principles and spirit of the invention, but these changes and modifications fall within the scope of the invention.
Although the embodiments have been described and illustrated separately above, and with respect to a partially common technique, it will be apparent to those skilled in the art that alternate and integration may be made between embodiments, with reference to one embodiment not explicitly described, and reference may be made to another embodiment described.
The above-described embodiments do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present invention.

Claims (19)

1. A dimmer compatible LED driver circuit comprising
A rectifying circuit for receiving an ac input signal and outputting a rectified signal subjected to rectification processing;
the power conversion circuit comprises a controllable switch tube, the input end of the controllable switch tube is coupled to the rectifying circuit, and the output end of the controllable switch tube is coupled to the LED load;
the switch control circuit is used for providing a switch control signal to control the switch state of the controllable switch tube, and the controllable switch tube executes on-off operation according to the switch control signal so as to control the output voltage of the output end of the power conversion circuit;
a linear control circuit connected between a negative terminal of the LED load and a reference ground to control a current flowing through the LED load such that an operating current of the LED load is maintained stable;
in a non-dimming state, the switch control circuit controls whether the power conversion circuit performs power conversion or not according to a current detection signal of the linear control circuit;
and in the dimming state, the switch control circuit controls the switch state of the controllable switch tube according to the output feedback signal of the power conversion circuit.
2. The LED driving circuit according to claim 1, wherein the switch control circuit controls the power conversion circuit to perform power conversion when the current detection signal is lower than a reference current.
3. The LED driving circuit according to claim 1, wherein the switch control circuit includes a trigger signal generating circuit that obtains a trigger signal from the current detection signal,
when the trigger signal is in an effective state, the switch control circuit controls the power conversion circuit to perform power conversion; when the trigger signal is in an invalid state, the switch control circuit controls the power conversion circuit to stop power conversion.
4. The LED driving circuit according to claim 3, wherein the linear control circuit comprises a first switching tube, a first resistor connected in series with the first switching tube, and an error circuit, one power terminal of the first switching tube is connected with a negative terminal of the LED load,
the error circuit obtains a third feedback voltage according to the sampling signals of the first switching tube and the first resistor connection node, and performs error amplification on the third feedback voltage and a third reference voltage so as to control the switching state of the first switching tube, so that the working current of the LED load is maintained at an expected value;
the trigger signal generating circuit detects the first switching tube and a first resistor connecting node to obtain the current detection signal, or the trigger signal generating circuit detects the grid voltage of the first switching tube to obtain the current detection signal.
5. The LED driving circuit of claim 3, wherein the switch control circuit comprises a feedback circuit,
in the non-dimming state, when the trigger signal is in an effective state, the feedback circuit controls the power conversion circuit to perform power conversion according to the output feedback signal of the power conversion circuit and a first reference signal.
6. The LED driving circuit of claim 5, wherein when the switch control circuit obtains the output feedback signal of the power conversion circuit from the output terminal of the power conversion circuit, the first reference signal is set to be greater than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit,
when the switch control circuit obtains an output feedback signal of the power conversion circuit according to the negative terminal of the LED load, the first reference signal is set to be larger than the conduction voltage drop of the linear circuit,
wherein the linear circuit conduction voltage drop is the product of the on-resistance of the linear control circuit and the expected operating current of the LED load.
7. The LED driving circuit according to claim 5, wherein in a dimming state, the feedback circuit controls a switching state of the controllable switching transistor according to an output feedback signal of the power conversion circuit and a second reference signal,
when the switch control circuit obtains an output feedback signal of the power conversion circuit according to the output end of the power conversion circuit, the second reference signal is set to be larger than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit,
when the switch control circuit obtains an output feedback signal of the power conversion circuit according to the negative terminal of the LED load, the second reference signal is set to be larger than the conduction voltage drop of the linear circuit,
wherein the linear circuit conduction voltage drop is the product of the on-resistance of the linear control circuit and the expected operating current of the LED load.
8. The LED driving circuit of claim 7, wherein,
when the second reference signal is set to be larger than the sum of the voltage drop of the LED load and the conduction voltage drop of the linear circuit, the second reference signal is set to be any value between 50 and 150V,
when the second reference signal is set to be larger than the conduction voltage drop of the linear circuit, the second reference signal is set to be any value between 50 and 150V different from the conduction voltage drop of the linear circuit.
9. The LED driver circuit of claim 7, wherein the second reference signal setting is consistent in size with the first reference signal.
10. The LED driving circuit of claim 1, wherein the switch control circuit further comprises a dimming detection circuit,
the dimming detection circuit detects the node voltage of the input end or the output end of the rectifying circuit to judge whether a dimmer exists,
when a dimmer exists, the switch control circuit controls the LED driving circuit to enter a dimming state;
when the dimmer is not present, the switch control circuit controls the LED drive circuit to enter a non-dimming state.
11. The LED driving circuit of claim 5, wherein the switch control circuit further comprises logic circuitry,
the logic circuit receives the output signals of the trigger signal generating circuit and the feedback circuit to generate the switch control signal.
12. The LED driving circuit of claim 1, wherein the power conversion circuit comprises an input capacitor, a Boost conversion circuit, and an output capacitor,
the input capacitor is connected between the output end of the rectifying circuit and the input end of the Boost conversion circuit,
the output end of the Boost converter is connected with the positive end of the LED load through the output capacitor,
the controllable switch tube is a main power switch tube of the Boost conversion circuit.
13. The LED driving circuit according to any of claims 1-11, wherein at least part of the LED driving circuit is integrated in one or more integrated chips.
14. A method of driving a dimmer compatible LED, the method being implemented using an LED driving circuit according to any one of claims 1-13, the method comprising the steps of:
detecting whether a dimmer exists between the connecting end of the alternating current input signal and the rectifying circuit, controlling the LED driving circuit to work in a non-dimming state or a dimming state according to the detection result,
in a non-dimming state, controlling whether the power conversion circuit performs power conversion or not according to a current detection signal of the linear control circuit;
in the dimming state, controlling the switching state of the controllable switching tube according to an output feedback signal of the power conversion circuit;
the current flowing through the LED load is controlled so that the working current of the LED load is kept stable.
15. The method of driving an LED as claimed in claim 14, wherein,
when the current sense signal, which characterizes the current of the linear control circuit, is lower than the reference current, a trigger signal of the active state is generated,
when the trigger signal is in an effective state, the power conversion circuit is controlled to perform power conversion, when the trigger signal is in an ineffective state, the power conversion circuit is controlled to stop power conversion,
wherein the reference current is set to a desired operating current of the LED load.
16. The LED driving method according to claim 14, wherein an output voltage of the power conversion circuit in the dimming state is greater than an output voltage of the power conversion circuit in the non-dimming state.
17. The LED driving method according to claim 16, wherein the output voltage of the output terminal of the power conversion circuit is controlled to be a preset voltage so that the magnitude of the input current of the power conversion circuit is equal to or greater than a first threshold current in the dimming state,
wherein the first threshold current is set to a magnitude such that the power factor of the LED driving circuit reaches at least 0.7.
18. A lighting system comprising an LED load and the LED driving circuit of any one of claims 1-13.
19. The lighting system of claim 18, wherein the voltage drop of the LED load is configured such that an absolute value of a difference between the voltage drop of the LED load and a peak value of the ac input signal is within a preset voltage range,
the preset voltage range is any value between 0 and 10V.
CN202311066517.6A 2023-08-22 2023-08-22 Light modulator compatible LED driving circuit, driving method and lighting system Pending CN117279153A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311066517.6A CN117279153A (en) 2023-08-22 2023-08-22 Light modulator compatible LED driving circuit, driving method and lighting system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311066517.6A CN117279153A (en) 2023-08-22 2023-08-22 Light modulator compatible LED driving circuit, driving method and lighting system

Publications (1)

Publication Number Publication Date
CN117279153A true CN117279153A (en) 2023-12-22

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311066517.6A Pending CN117279153A (en) 2023-08-22 2023-08-22 Light modulator compatible LED driving circuit, driving method and lighting system

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Country Link
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