WO2011029383A1

WO2011029383A1 - Led lamp driving circuit

Info

Publication number: WO2011029383A1
Application number: PCT/CN2010/076689
Authority: WO
Inventors: 段卫垠
Original assignee: 深圳市航嘉驰源电气股份有限公司
Priority date: 2009-09-14
Filing date: 2010-09-07
Publication date: 2011-03-17
Also published as: CN102014537A; CN102014537B

Abstract

An LED lamp driving circuit is provided, which includes a voltage stabilizing circuit, a current stabilizing circuit and a feedback circuit. The voltage stabilizing circuit is connected to the LED lamp, provides and adjusts the driving voltage of the LED lamp. The current stabilizing circuit is connected to the LED lamp, provides and adjusts the driving current of the LED lamp. The feedback circuit is connected to the voltage stabilizing circuit and the current stabilizing circuit respectively, collects the electrical signals of the current stabilizing circuit, and produces feedback signals, which are used for the voltage stabilizing circuit and the current stabilizing circuit to perform a synchronous adjustment. The LED lamp driving circuit makes the voltage stabilizing circuit and the current stabilizing circuit to be adjusted synchronously by using the feedback circuit, achieves a purpose of adjusting synchronously and stabilizing the operating current and the operating voltage of the LED lamp, improves the working efficiency of a lighting system, and prolongs the service life of the lighting system.

Description

LED light drive circuit

Technical field

The present invention relates to the field of driving circuit technologies, and in particular, to an LED lamp driving circuit.

Background technique

With the intensification of the world energy crisis, reducing energy consumption and protecting the environment have become a consensus. LED lighting will replace the first- and second-generation lighting technologies with low energy efficiency. When used, high-power LED lights use multiple LED lights in series, each string is driven separately. Since the characteristics of the LED lamp require constant voltage constant current driving, it is required that the power supply of the LED lamp simultaneously provide several separate constant voltage constant current power sources.

4 is a circuit configuration of a prior art LED lamp driving circuit. Referring to FIG. 4, the driving circuit of the existing LED lighting lamp uses a voltage stabilizing module and a steady current module to control the operating voltage and current of the LED lamp.

Fig. 5 is a diagram showing the structure of an LED lamp driving circuit using a linear steady current line in the prior art. Referring to FIG. 5, the output voltage of the voltage stabilizing module is a fixed value greater than the maximum forward voltage of the series LED lamp, that is, the input voltage of the LED lamp is not adjusted according to the working state of the LED lamp. The steady current module uses the linear steady current technique to control the operating current of the LED lamp. By directly sampling the current of the series LED lamp, it compares with the reference reference voltage to adjust the conduction resistance of the steady flow tube, thereby controlling the operating current of the LED lamp. Since the operating current of the LED lamp varies with its input voltage and operating temperature, if the switching power supply is used to output a stable DC voltage, and then through multiple sets of linear adjustment circuits to stabilize the current, multi-channel constant current output is realized, at -40 ° C outdoors. Under the operating conditions of -50 ° C, the function, efficiency, and life requirements will not be met. Moreover, when the input voltage is greater than the maximum forward voltage setting of the series LED lamp, when the operating temperature reaches 50 ° C, the LED lamp reaches the minimum forward voltage, and the linear steady flow tube will reach the maximum power consumption. Value, at this moment, the efficiency of the LED lamp system will also decrease, and the temperature of the linear regulator tube will rise, which shortens the service life of the LED lamp.

Fig. 6 is a diagram showing the structure of an LED lamp driving circuit using a PWM current stabilizing line in the prior art. Referring to FIG. 6, the output voltage of the voltage stabilizing module is a fixed value greater than the maximum forward voltage of the series LED, that is, the input voltage of the LED light is not adjusted according to the working state of the LED light. The steady current module uses current mode PWM to control the operating current of the LED lamp. When the input voltage of the LED lamp is greater than the maximum forward voltage of the series LED lamp, when the operating temperature reaches 50 °C, the LED lamp reaches the minimum value of the forward conduction voltage value, and the duty of the BO-OST converter The LED luminaire will achieve optimum efficiency by shrinking to a minimum. However, when the operating temperature reaches -40 ° C, the LED lamp reaches the maximum value of the forward conduction voltage, the duty ratio of the BOOST converter will reach the maximum value, and the efficiency of the LED lamp system will decrease. Moreover, although the driving circuit can meet the driving requirements of the LED lamp, it uses many devices and the circuit is complicated, which makes the cost high.

In summary, the existing technical solutions can not synchronously adjust the input voltage and working current of the LED, the power consumption of the linear steady current technology is high, and the use cost of the PWM steady current technology is high, and the high-power LED outdoor can not be fully satisfied. Technical requirements for the lamp.

Summary of the invention

The main object of the present invention is to provide an LED lamp driving circuit, which aims to improve the working efficiency of the LED lamp and prolong the service life of the lighting system.

The LED lamp driving circuit of the invention comprises:

a voltage stabilizing circuit connected to the LED lamp to provide and adjust a driving voltage of the LED lamp;

a steady current circuit connected to the LED lamp to provide and adjust the driving current of the LED lamp;

The feedback circuit can be respectively connected with the voltage stabilizing circuit and the steady current circuit, and can collect the electric signal of the steady current circuit and generate a feedback signal for synchronous adjustment of the voltage stabilizing circuit and the steady current circuit.

Preferably, the feedback circuit includes:

The acquisition circuit collects the voltage at the output end of the steady current circuit as a sampling voltage and transmits it to the comparison circuit;

Comparing the circuit, connecting with the acquisition circuit, and generating a level signal according to the change of the sampling voltage;

The switch circuit can be respectively connected with the comparison circuit and the voltage stabilization circuit, and generate a feedback signal according to the level signal output by the comparison circuit.

Preferably, the comparison circuit may include a voltage comparator and a power source, and the input ends of the voltage comparators are respectively connected to the acquisition circuit and the power source, and compare the sampling voltage with the voltage supplied by the power source, and generate a level signal according to the comparison result.

Preferably, the switching circuit may include a diode, wherein a positive pole of the diode is connected to an output end of the voltage comparator, and a negative pole is connected to the voltage stabilizing circuit.

Preferably, the acquiring circuit may include a first RC network and a second RC network; the two ends of the first RC network are respectively connected to the output end of the snagging circuit and the non-inverting input end of the comparison circuit; One end is grounded and the other end is connected to the non-inverting input of the voltage comparator.

Preferably, the comparison circuit further includes a third RC network, wherein both ends of the third RC network can be respectively connected to the non-inverting input terminal and the output terminal of the comparison circuit.

Preferably, the voltage stabilizing circuit may include at least one voltage adjusting unit that adjusts the input voltage to a voltage matched with the LED lamp, wherein the voltage adjusting unit may include a voltage output end and a voltage feedback end; the voltage feedback end may be The output end of the switch circuit is connected, and the voltage at the voltage output terminal is adjusted according to the voltage change at the output end of the switch circuit to provide and adjust the driving voltage of the LED lamp.

Preferably, the voltage regulating unit is a current type or voltage type PWM DC/DC converter.

Preferably, the current stabilizing circuit can include an operational amplifier, a transistor and a power supply; the non-inverting input of the operational amplifier can be connected to the power supply, the inverting input can be connected to the source of the transistor, and the output can be connected to the gate of the transistor; A resistor can be connected in series between the source and the ground, and the drain can be connected to the LED lamp to provide and adjust the driving current of the LED lamp.

Preferably, the current stabilizing unit further includes a sixth RC network and a seventh RC network. The two ends of the sixth RC network can respectively connect the source of the transistor and the inverting input of the operational amplifier; One end of the RC network can be connected to the output of the operational amplifier, and the other end can be connected to the inverting input of the operational amplifier to form a negative feedback of the operational amplifier.

The LED lamp driving circuit of the invention makes the voltage regulation and the steady current circuit synchronously adjust through the feedback circuit, and achieves the purpose of simultaneously adjusting and stabilizing the working current and the working voltage of the LED lamp. Therefore, the LED lamp driving circuit of the present invention solves the problem of high power consumption of the linear steady current circuit in the prior art, improves the efficiency of the lighting system, and prolongs the service life of the lighting system; and the electronic device used by the PWM current stabilizing circuit Less, saving costs.

DRAWINGS

1 is a schematic structural view of an LED lamp driving circuit in an embodiment of the present invention;

2 is a schematic circuit diagram of an LED lamp driving circuit in an embodiment of the above embodiment;

3 is a schematic structural view of an LED lamp driving circuit in another embodiment of the above embodiment;

4 is a schematic circuit diagram of a prior art LED lamp driving circuit;

5 is a schematic diagram showing the circuit structure of an LED lamp driving circuit using a linear steady current line in the prior art;

6 is a schematic diagram showing the circuit structure of an LED lamp driving circuit using a PWM current stabilizing line in the prior art.

The implementation, functional features, and advantages of the present invention will be further described in conjunction with the embodiments.

detailed description

It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Fig. 1 shows the structure of an LED lamp driving circuit of the present invention. Referring to FIG. 1, the driving circuit includes a voltage stabilizing circuit 10, a current stabilizing circuit 20, and a feedback circuit 30. The voltage stabilizing circuit 10 is connected to the LED lamp 40 to supply and adjust the driving voltage of the LED lamp 40, that is, the input voltage of the LED lamp 40. The steady current circuit 20 has an output connected to the LED lamp 40 to supply and adjust the driving current of the LED lamp 40. The feedback circuit 30 is connected to the voltage stabilizing circuit 10 and the steady current circuit 20, respectively, and collects the electrical signal of the steady current circuit 20, and processes the collected electrical signal to generate a feedback signal. The voltage stabilizing circuit 10 performs adjustment of the output voltage based on the feedback signal.

During the operation of the LED lamp, the operating voltage of the LED lamp 40 decreases as the ambient temperature rises and its own heat increases, and the current flowing through the LED lamp 40 increases, that is, the current at the output end of the steady current circuit 20 increases. Big. The feedback circuit 30 will collect the change of the current at the output of the steady current circuit 20 and generate a feedback signal. After receiving the feedback signal, the voltage stabilizing circuit 10 will lower the output voltage, so that the current flowing through the LED lamp 40 will also decrease. . The feedback circuit 30 collects the change of the current of the LED lamp 40, and then generates a feedback signal, and the voltage stabilizing circuit 10 adjusts the output voltage according to the feedback signal, thereby synchronously adjusting the operating current of the LED lamp. After repeated cycle adjustment, the input voltage and the operating current of the LED lamp 40 reach an optimal balance state.

The invention feeds back the electric signal of the steady current circuit in the LED lamp driving circuit to the voltage stabilizing circuit through the feedback circuit, and the voltage stabilizing circuit adjusts the output voltage according to the feedback signal, so that the working current of the LED lamp can be synchronously adjusted, so that the LED The input voltage of the lamp and the working current can be adjusted synchronously, and after repeated cycle adjustment, the input voltage of the LED lamp and the working current can reach an optimal balance state, which reduces the power consumption of the steady current circuit and improves the LED lamp. Work efficiency.

Fig. 2 shows the circuit configuration of an LED lamp driving circuit in one embodiment of the above embodiment. Referring to FIG. 2, the feedback circuit 30 includes a switch circuit 31, a comparison circuit 32, and an acquisition circuit 33. The comparison circuit 32 includes a voltage comparator U2 and a power supply V3. The voltage comparator U2 includes a non-inverting input terminal and an inverting input terminal. When the voltage of the non-inverting input terminal is greater than the voltage of the inverting input terminal, the high level is output; otherwise, the low level is output. The power supply V3 provides a reference voltage that is coupled to the inverting input of the voltage comparator U2. The switching circuit 31 includes a diode D. The collecting circuit 33 collects the voltage at the output end of the steady current circuit 20 as a sampling voltage, and includes a first RC network Z1. One end of the first RC network Z1 is connected to the output end of the tempering circuit 20, and the other end is connected to the voltage comparator U2. Connected to the non-inverting input. The output of the voltage comparator U2 is connected to the anode of the diode D. When the sampling voltage is greater than the reference voltage, the voltage comparator U2 outputs a high level, and the diode D is turned on; otherwise, the voltage comparator U2 outputs a low level, and the diode D is turned off.

In the above embodiment, the acquisition circuit 33 further includes a second RC network Z2. One end of the second RC network Z2 is grounded, and the other end is connected to the non-inverting input terminal of the voltage comparator U2. The first RC network Z1 and the second RC network Z2 form a voltage dividing sampling circuit, which can not only perform voltage division sampling on the output end of the current stabilizing circuit 20, but also filter the output voltage of the current stabilizing circuit 20 well. effect.

In the above embodiment, the comparison circuit 32 further includes a third RC network Z3. One end of the third RC network Z3 is connected to the output terminal of the voltage comparator U2, and the other end is connected to the non-inverting input terminal of the voltage comparator U2. Moreover, the second RC network Z2 and the third RC network Z3 constitute an active filter, which well eliminates the resonance generated by the LC in the RC network.

The voltage comparator U2 described above may be another comparator such as an operational amplifier. The diode described above may be another one-way conduction element such as a Zener diode.

In the above embodiment, the voltage stabilizing circuit 10 includes a voltage regulating circuit 11. The voltage adjusting unit 11 adjusts the input voltage to a voltage matching the LED lamp, is connected to the output terminal of the switching circuit 31, and adjusts the voltage at the output terminal of the voltage adjusting circuit 11 in accordance with the voltage change at the output terminal of the switching circuit 31.

In the above embodiment, the voltage regulating circuit 11 is preferably a voltage type or current type DC/DC converter PSU1, and the voltage feedback terminal FB of the DC/DC converter PSU1 is connected to the output end of the switching circuit 31, according to the switching circuit 31. The voltage at the output changes to adjust the voltage at the voltage output Vout. The voltage output terminal Vout is also connected to the voltage feedback terminal FB, so that the DC/DC converter can adjust the voltage output in time according to the voltage change of the voltage output terminal Vout. For example, when the output voltage of the DC/DC converter is unstable and fluctuating, the voltage output terminal Vout feeds back the output voltage value to the voltage feedback terminal FB of the DC/DC converter, and the DC/DC converter is based on the voltage feedback terminal FB. The voltage change adjusts the voltage at the output until it reaches a steady state, thus achieving the purpose of voltage regulation.

In the above embodiment, the voltage stabilizing circuit 10 further includes a fourth RC network Z4 and a fifth RC network Z5. The fourth RC network Z4 is connected in series with the fifth RC network Z5, and is connected in series between the voltage feedback terminal FB and the ground, and functions as a current limiting voltage divider and filtering in the circuit. Because the voltage value of the voltage feedback terminal FB of the DC/DC converter is relatively small, the fourth resistor-capacitor network Z4 and the fifth resistor-capacitor network Z5 can ensure that the voltage value of the voltage feedback terminal FB is within the normal range.

In the above embodiment, the voltage stabilizing circuit 10 further includes an operational amplifier U1. The operational amplifier U1 can make the voltage of the voltage output terminal Vout small, so that the voltage of the input voltage feedback terminal FB satisfies the normal range value. Further, the operational amplifier U1 can prevent the feedback signal of the switching circuit 31 from flowing into the voltage output terminal and affecting the voltage of the voltage output terminal Vout. The non-inverting input terminal of the operational amplifier U1 is connected to the voltage output terminal Vout, the inverting input terminal is connected to the DC/DC converter, and the output terminal is connected to the voltage feedback terminal FB.

In the above embodiment, the voltage stabilizing circuit 10 may further include at least two DC/DC converters PSU1 connected in series such that the output ends of the feedback circuit 30 are respectively connected to the voltage feedback terminals FB of the respective DC/DC converters, thereby further ensuring the voltage regulation. Accurate adjustment of the output voltage of circuit 10.

In the above embodiment, the current stabilizing circuit 20 includes an operational amplifier U3, a transistor Q1, and a power supply V1. The non-inverting input terminal of the operational amplifier U3 is connected to the power source V1; the inverting input terminal is connected to the source of the transistor Q1, and the sixth RC network Z6 is connected in series between the source and the inverting input terminal; the output terminal is connected to the gate of the transistor Q1. Extremely connected. A resistor R1 is further connected in series between the source of the transistor Q1 and the ground; and the drain is connected to the LED lamp 40.

When the voltage of the drain of the transistor Q1 rises, the operational amplifier U3 lowers the output voltage of the operational amplifier U3 because the voltage of the inverting input rises and is higher than the voltage supplied by the power supply V1, thereby lowering the current of the drain of the transistor Q1. the goal of.

The steady current circuit 20 further includes a seventh RC network Z7. The seventh resistor-capacitor network Z7 has one end connected to the output terminal of the operational amplifier U3 and the other end connected to the inverting input terminal of the operational amplifier U3.

The above transistor may be a metal oxide semiconductor (Metal-Oxide-Semiconductor) Field-Effect Transistor (MOSFET) or bipolar transistor (BIPOLAR TRANSISTOR).

The value of the power source V1 described above can be selected according to the characteristics of the transistor Q1, so that the transistor Q1 is in an optimal operating state.

The first resistance-capacitor network Z1, the second RC network Z2, the third RC network Z3, the fourth RC network Z4, the fifth RC network Z5, the sixth RC network Z6, and the seventh RC network Z7 are both For the RC resistance-capacitor network, the connection structure of R and C and the values of R and C in the structure can be determined according to the characteristics of the circuit.

Fig. 3 shows the structure of an LED lamp driving circuit in another embodiment of the above embodiment. Referring to FIG. 3, the LED lamp driving circuit can drive multiple LED lamps connected in series, including a voltage stabilizing circuit 10, a plurality of current stabilizing circuits 20(1)... 20(n) and multiple feedback circuits 30(1)... 30(n). Multiple LEDs connected in series are connected in parallel and connected to the voltage stabilizing circuit 10. Each LED light is connected to a steady current circuit. For example, the steady current circuit 20(1) is connected to the LED lamp 40(1), and the feedback circuit 30(1) is respectively connected to the voltage stabilization circuit 10 and the steady current circuit 20(1) to collect the electricity of the steady current circuit 20(1). The signal is generated and a feedback signal is generated for synchronous adjustment of the voltage stabilizing circuit 10 and the steady current circuit 20(1). The steady current circuit 20(n) is connected to the LED lamp 40(n), and the feedback circuit 30(n) is respectively connected to the voltage stabilization circuit 10 and the steady current circuit 20(n) to collect the electrical signal of the steady current circuit 20(n). A feedback signal is generated for synchronous adjustment of the voltage stabilizing circuit 10 and the steady current circuit 20(n). Regardless of which operating voltage of the series connected LED lamp 40 changes, the feedback circuit 30 collects the change of the voltage at the output end of the steady current circuit 20 and feeds it back to the voltage stabilizing circuit 10 for adjustment, thereby achieving synchronous adjustment of the steady current circuit.

A logic circuit 50 may be connected between the voltage stabilizing circuit 10 and the feedback circuit 30, and the feedback signal generated by the plurality of feedback circuits 30 may be logically operated, and then input to the voltage feedback terminal FB of the voltage stabilizing circuit 10. For example, the feedback signals generated by the plurality of feedback circuits 30 are subjected to a maximum value or an averaging operation.

The voltage regulator circuit, the current stabilizing circuit and the feedback circuit of the LED lamp driving circuit can also form an integrated circuit to facilitate large-scale production and greatly reduce the manufacturing cost.

The LED lamp driving circuit of the invention makes the voltage regulation and the steady current circuit synchronously adjust through the feedback circuit, and achieves the purpose of simultaneously adjusting and stabilizing the working current and the working voltage of the LED lamp. Therefore, the LED lamp driving circuit of the present invention solves the problem of high power consumption of the linear current stabilizing circuit in the prior art, improves the efficiency of the lighting system, and prolongs the service life of the lighting system; and the electrons used by the PWM current stabilizing circuit Less equipment and cost savings.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related The technical field is equally included in the scope of patent protection of the present invention.

Claims

An LED lamp driving circuit, comprising:

a voltage stabilizing circuit connected to the LED lamp to provide and adjust a driving voltage of the LED lamp;

a steady current circuit connected to the LED lamp to provide and adjust the driving current of the LED lamp;

The feedback circuit is respectively connected with the voltage stabilizing circuit and the steady current circuit, collects the electric signal of the steady current circuit, and generates a feedback signal for synchronous adjustment of the voltage stabilizing circuit and the steady current circuit.
The LED lamp driving circuit of claim 1 wherein said feedback circuit comprises:

The acquisition circuit collects the voltage at the output end of the steady current circuit as a sampling voltage and transmits it to the comparison circuit;

Comparing the circuit, connecting with the acquisition circuit, and generating a level signal according to the change of the sampling voltage;

The switching circuit is respectively connected with the comparison circuit and the voltage stabilization circuit, and generates a feedback signal according to the level signal output by the comparison circuit.
The LED lamp driving circuit according to claim 2, wherein the comparison circuit comprises a voltage comparator and a power source, and the input terminals of the voltage comparator are respectively connected to the acquisition circuit and the power source, and the sampling voltage and the power supply are compared. The voltage is generated and a level signal is generated based on the comparison result.
The LED lamp driving circuit according to claim 3, wherein the switching circuit comprises a diode, wherein a positive electrode of the diode is connected to an output end of the voltage comparator, and a negative electrode is connected to the voltage stabilizing circuit.
The LED lamp driving circuit of claim 4, wherein the acquisition circuit comprises a first RC network and a second RC network; the two ends of the first RC network are respectively connected to the output of the RC circuit And the non-inverting input end of the comparison circuit; one end of the second RC network is grounded, and the other end is connected to the non-inverting input end of the comparison circuit.
The LED lamp driving circuit of claim 5, wherein the comparison circuit further comprises a third RC network, wherein two ends of the third RC network are respectively connected to the non-inverting input terminal and the output end of the comparison circuit .
The LED lamp driving circuit according to any one of claims 1 to 6, wherein the voltage stabilizing circuit comprises at least one voltage regulating circuit connected to an output end of the switching circuit and adjusted according to a voltage change at an output end of the switching circuit. The voltage at the voltage output provides and regulates the drive voltage of the LED lamp.
The LED lamp driving circuit according to claim 7, wherein said voltage regulating unit is a current type or a voltage type PWM DC/DC converter.
The LED lamp driving circuit according to any one of claims 1 to 6, wherein the current stabilizing circuit comprises an operational amplifier, a transistor and a power supply; the non-inverting input terminal of the operational amplifier is connected to a power source, and an inverting input The terminal is connected to the source of the transistor, the output terminal is connected to the gate of the transistor; a resistor is connected in series between the source and the ground of the transistor, and the drain is connected with the LED lamp to provide and adjust the driving current of the LED lamp.
The LED lamp driving circuit of claim 9, wherein the current stabilizing unit further comprises a sixth RC network and a seventh RC network; the two ends of the sixth RC network are respectively connected to the transistor The source and the inverting input of the operational amplifier; one end of the seventh RC network is connected to the output of the operational amplifier, and the other end is connected to the inverting input of the operational amplifier to form a negative feedback of the operational amplifier.