WO2016024647A1 - Power circuit for led lighting and power control method for led lighting using same - Google Patents

Abstract

The purpose of the present invention is to provide a power circuit for LED lighting and a power control method for LED lighting in which the power circuit increases voltage of a valley part of a bridge output voltage, which is a problem when configuring a circuit that operates with alternating current (AC) power, such as to enable current to continuously flow at a constant level while an LED light is on and thereby prevent generation of flicker and significantly reduce ripple, without using components such as an electrolytic condenser or a transformer in order to maximize the durability and reliability of the LED light. Accordingly, optical quality is remarkably enhanced. The power circuit detects a valley portion which drops under a predetermined reference from a voltage waveform outputted through a bridge rectifier; and allows electric charge, charged to the condenser at the detected timing, to be discharged, thereby increasing voltage of the valley portion and allowing the current in the valley portion to constantly flow with respect to the current supplied to the LED.

Description

Power circuit for LED lighting and power control method for LED lighting using the same

The present invention relates to a power supply circuit for LED lighting, and more particularly, to a power supply circuit for power control for lighting generated from the LED device in a lighting device equipped with an LED device.

In the conventional LED lighting apparatus using AC power, a valley portion in which voltage drops as shown in FIG. 1 after bridge rectification occurs, which causes the LED driving current to be output near zero or a very small output value in the valley portion. In this case, a ripple phenomenon occurs in this portion, and in particular, as illustrated in FIG. 1, there is a problem in that a flicker occurs in the lowest end point of the voltage waveform, that is, the zero cross portion.

In order to solve this problem, conventionally, an AC power input from the outside is rectified using a rectifier, smoothed using an electrolytic capacitor, and then a voltage level is converted using a transformer or the like and mainly supplied to an LED. .

However, the electrolytic capacitor used in the prior art has a large volume, which makes it difficult to miniaturize the size of the driving circuit for driving the LED lighting device, and also shortens the life of components such as a capacitor, thereby reducing the lifetime of the entire LED driving circuit. Cause problems.

In addition, the transformer used in the prior art also has a problem that the volume is considerably large and there is a problem in efficiency, compared to other devices, it is difficult to reduce the size of the drive circuit.

In order to maximize the durability and reliability of the LED lighting, the present invention is to configure the circuit driven by an AC power supply without using components such as an electrolytic capacitor or a transformer. Power supply circuit for LED lighting and LED lighting using the same to improve the light quality by increasing current so that the current continuously flows to a certain level while the LED lighting is turned on, thereby preventing flicker and significantly reducing ripple. It is to provide a power control method for.

 The LED lighting power supply circuit according to an embodiment of the present invention is a power supply circuit for LED lighting for controlling the power supply for the LED light driven by the AC power source, the rectifier rectifying AC power and the current rectified by the bridge rectifier And a condenser charged by the condenser and detecting a valley portion falling below a predetermined reference from a voltage waveform output through the bridge rectifier to discharge the charge charged in the condenser at the detected time point. It includes a control unit for controlling so that a constant current flows in the valley portion with respect to the current supplied to the LED to raise the.

Also preferably, the controller may include a valley voltage detector configured to detect a falling time point at which the drop voltage starts to fall below a preset reference voltage from the voltage waveform output through the bridge rectifier, and a predetermined width at the detected falling time point. The control pulse generating unit for generating a pulse and the charge charged in the capacitor at the valley voltage detection zero cross position as the control pulse is discharged to discharge the voltage of the valley portion of the current waveform of the LED to increase the current It characterized in that it comprises a switch to flow.

Also preferably, further comprising a separate dedicated bridge for rectifying the AC current input from the AC power source, wherein the valley voltage detector is configured to detect the falling time using the output waveform passed through the dedicated bridge. It features.

Also preferably, the control unit may further include a voltage level adjusting unit for adjusting a level of an output voltage determined according to a rated current of an LED lamp or the like with respect to the voltage controlled by the valley voltage detector, the control pulse generator, and the switch. It is characterized by including.

On the other hand, the power control method for the LED lighting according to an embodiment of the present invention, a power control method for the LED lighting using a power supply circuit for LED lighting for controlling the power for the LED lighting driven by AC power, the LED The lighting power supply circuit includes a bridge rectifier for rectifying AC power and a capacitor charged by a current rectified by the bridge rectifier, and detects a valley portion falling below a predetermined reference from a voltage waveform output through the bridge rectifier. step; And controlling the electric current to be supplied to the LED to increase the voltage of the valley portion by discharging the electric charges charged in the capacitor at the detected time point so that a constant current flows in the valley portion with respect to the current supplied to the LED.

Also preferably, in the detecting of the valley portion, the voltage value output through the bridge rectifier is adjusted using a resistor to be an input voltage of a comparator, and a preset reference voltage is compared with an input voltage of the comparator. Detecting a falling time point at which the input voltage starts to fall below the reference voltage, and controlling the current to flow in the valley portion, the pulse having a predetermined width at the detected falling time point. Generating a voltage, and causing the electric current to flow by increasing the voltage of the valley portion of the current waveform of the LED by discharging the charge charged in the capacitor at the valley voltage detection zero cross position as the control pulse is generated. Characterized in that it comprises a.

The power supply circuit for LED lighting according to the present invention comprises a circuit driven by an alternating current (AC) power source without using components such as an electrolytic capacitor or a transformer in order to maximize the durability and reliability of the LED lighting, but the valley portion of the bridge output voltage By increasing the voltage of the LED, the current flows at a constant level while the LED lamp is turned on, thereby preventing flicker and significantly reducing ripple, thereby significantly improving the light quality of the LED light.

1 is a graph showing a simulation result for the waveform of the output voltage and output current of the conventional LED lighting equipment.

2 is a view showing an example of a power supply circuit for LED lighting according to an embodiment of the present invention.

Figure 3 (a) shows the voltage output waveform at the a and b position through the bridge in the circuit shown in Figure 2, (b) detects the valley portion in the valley voltage detector in the circuit shown in FIG. (C) shows the control pulse waveform at the d position passing through the control pulse generator in the circuit shown in Figure 2, (d) is a switch in the circuit shown in FIG. Fig. 2 shows the voltage output waveform at the e position, which is the output side of Fig. 2, and (e) shows the voltage output waveform at the f position through the voltage level adjusting section in the circuit shown in Fig. 2.

4 is a flowchart illustrating a power control method for the LED lighting according to an embodiment of the present invention.

Hereinafter, a power supply circuit for LED lighting and a power control method for LED lighting using the same according to the present invention will be described in more detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 10 denotes an AC power source, reference numeral 20 denotes a bridge rectifier, reference numeral 30 denotes a dedicated bridge used for valley voltage detection and control pulse generation of a controller, reference numeral 40 denotes a capacitor, and reference numeral 50 Silver switch, and reference numeral 60 denotes an LED lighting device including a plurality of LED elements 61, respectively.

In addition, reference numeral 100 denotes a controller in charge of the main function of the LED lighting power supply circuit according to the present invention, wherein the controller 100 is a valley voltage detector 110, a control pulse generator 130, and a voltage level adjuster 130. ) May be included.

The output voltage waveform at the a position or the b position after passing through the bridge rectifier 20 or the dedicated bridge 30 after the AC input by the AC power supply 10 is shown in FIG. A certain number of mountain-shaped waveforms are made according to the frequency, and the valley portion A is formed between the waveforms and the waveforms as described above.

In the power supply circuit, the voltage output as shown in FIG. 3A is held by the capacitor 40. Here, Vp shown in (a) of FIG. 3 will be 220V as an AC input voltage. In the figure, xp refers to the output waveform.

When the current according to the output voltage of the waveform (xp) as shown in Fig. 3 (a) is input to the LED lighting device 60, the valley portion (A) can not supply a constant current because of the valley portion The weak output at Rx generates periodic ripples, especially at the zero-cross point where the current supply is temporarily interrupted, resulting in flicker.

Therefore, in the power supply circuit for LED lighting according to the embodiment of the present invention, the ripple generated in the valley portion by appropriately detecting the valley portion in the waveform of the output voltage passing through the bridge rectifier as described above and increasing the voltage of the portion thereof. The purpose is to prevent the flicker phenomenon in advance to ensure that the rated current flows stably in the LED lighting device (60).

To this end, the valley voltage detection unit 110 of the controller 100 functions to detect a falling time point that starts to fall below a predetermined reference voltage from the voltage waveform output through the bridge rectifier.

Here, the voltage for detecting the valley portion may preferably use a separate dedicated bridge 30 without using the common bridge 20.

The valley voltage detector 110 may be implemented using a comparator. The comparator inputs a preset reference voltage to the + terminal and? When the output voltage is input to the terminal, the output voltage is compared with the reference voltage to detect a position lower than the reference voltage in the output voltage.

However, since the bridge output voltage has a high voltage value, it is necessary to lower the voltage value in order to compare the voltages. This can be lowered by using the resistors R1 and R2 installed at the output terminal of the dedicated bridge 30 shown in FIG. The waveform according to the voltage adjusted using the resistors R1 and R2 may be represented by the xi waveform of FIG. 3B. In FIG. 3B, the voltage value was adjusted from Vp to Vi by the resistors R1 and R2.

As shown in (b) of FIG. 3, the valley voltage detection unit compares the reference voltage Va with the comparator input voltage and starts to fall below the reference voltage Va at the input voltage t1 and t2. , t3, t4, etc.).

Here, the reference voltage Va is a value which is predetermined and fixed in advance as a reference voltage of a degree capable of appropriately specifying the valley portion A of the voltage waveform xp.

Here, a time point at which the input voltage starts to fall below the reference voltage Va will be referred to as a falling time point.

As described above, when the falling time point t1, t2, t3, t4, etc. is detected by the reference voltage, the control pulse generator 120 may set the predetermined width W as shown in (c) of FIG. 3. To generate a pulse. The control pulse as shown in (c) of FIG. 3 can be confirmed at the d position of the power circuit shown in FIG.

Then, the switch 50 is driven by the control pulse generated as described above, while the switch 50 is turned on while the control pulse is generated, the electric charge that has been charged in the capacitor 40 is discharged and e on the circuit. At the position, a voltage waveform as shown in Fig. 3D is output. Here, the capacitor 40 is preferably a ceramic capacitor having a large capacity.

For example, if the peak current is 190 mA and the state is controlled by the rated current 100 mA, since a substantial portion of energy is always left in the capacitor 40, the rising magnitude of the voltage rising portion can be further increased.

As shown in (d) of FIG. 3, it can be seen that the voltage rises in the valley portion A so that the control voltage waveform becomes a certain level as a whole. Here, the portion where the voltage of the valley portion rises in the voltage waveform shown in FIG. 3D is referred to as a voltage rising portion B.

In the voltage waveform that originally passed the bridge rectification, the valley part has a very low voltage and zero cross, so the current flows or turns off very weakly. As described above, the switch is driven by the detection of the falling time point and the generation of a control pulse based thereon As the voltage rising portion (B) occurs in the valley portion, the current can flow relatively more stably, thereby preventing flicker and significantly reducing the ripple phenomenon.

On the other hand, as described above, the voltage controlled by the control pulse is adjusted by the voltage level adjusting unit 130 as a whole, and the current is applied to the LED lighting device 60 which is the load according to the adjusted voltage.

The voltage level adjusting unit 130 adjusts the voltage level of the control voltage according to the rated current so that a constant rated current flows according to the number or capacity of the LEDs 61 constituting the LED lighting device 60.

The voltage level adjusting unit 130 may be implemented to output a constant voltage level by using an oscillator for generating a pulse having a certain period.

3E shows a state in which the voltage level is adjusted to Vf. If the level of Vf is adjusted lower than the voltage rising portion, it is preferable because it can supply a constant current according to a substantially constant voltage without the curved portion of the voltage waveform.

If Vf is adjusted to a slightly higher level, there may be a fine ripple in the voltage waveform, which may result in a fine ripple. This is undeniable.

On the other hand, with reference to Figure 4 will be described a power control method for the LED lighting according to an embodiment of the present invention. Power control method for the LED lighting according to an embodiment of the present invention has already been described to some extent in the process of describing the power circuit for LED lighting according to the present invention, but summarized by using the flowchart shown in FIG. To explain.

First, the AC power of the power circuit is input for the operation of the LED lighting device (S10), and thus the voltage passing through the bridge rectifier is held in the capacitor.

In order to generate a clean signal without noise, the valley voltage detector and the control pulse generator of the control unit of the present invention preferably use separate dedicated bridges, after the dedicated bridges are rectified with respect to the input power from the AC power source ( S20), the rectified voltage is adjusted to a voltage value by the resistors R1 and R2 (see FIG. 2) and input to the valley voltage detection unit.

The valley voltage detection unit compares a preset reference voltage with the input voltage to detect a falling time point at which the voltage begins to fall below the reference voltage (S30), and the control pulse generator generates a pulse having a predetermined width at the falling time point. To generate (S40).

The switch operates according to the pulse generated by the control pulse generator (S50), and the charge charged in the capacitor is discharged every time the switch is turned on (S60), and the voltage rises in the valley portion of the bridge output waveform. The rising portion occurs (S70).

On the other hand, the voltage level adjusting unit generates a predetermined pulse to constantly adjust the voltage level (S80), the current input to the LED device is controlled according to the adjusted voltage as described above (S90).

By controlling the voltage through a series of processes as described above and adjusting the voltage to an appropriate level, a fairly constant current can flow in the LED lighting device, thereby significantly reducing flicker and ripple, which has been a problem in the prior art. It is possible to significantly improve the light quality.

Since the power supply circuit for LED lighting according to the present invention requires a high breakdown voltage PFET, a greater effect than that of the one chip can be achieved.

The best mode for carrying out the invention is described in the section.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for LED lighting and can be widely used in the industrial field related to a lighting device equipped with an LED element.

Claims (6)

As a power supply circuit for LED lighting that controls the power to the LED light driven by AC power, A bridge rectifier for rectifying AC power and a capacitor charged by a current rectified by the bridge rectifier, The valley portion falling below a predetermined reference is detected from the voltage waveform output through the bridge rectifier to discharge the charge charged in the capacitor at the detected time point, thereby increasing the voltage of the valley portion and being supplied to the LED. Power supply circuit for LED lighting comprising a control unit for controlling a constant current to flow in the valley portion with respect to the current. The method of claim 1, wherein the control unit, A valley voltage detecting unit detecting a falling time starting to fall below a predetermined reference voltage from a voltage waveform output through the bridge rectifier; A control pulse generator for generating a pulse having a predetermined width at the detected falling time point; And a switch for causing the electric current to flow by increasing the voltage of the valley portion of the current waveform of the LED by discharging the electric charge charged in the capacitor at the valley voltage detection zero cross position as the control pulse is generated. Power supply circuit for LED lighting. The method of claim 2, Further comprising a separate dedicated bridge for rectifying the alternating current input from the AC power source, the valley voltage detector for detecting the falling time using the output waveform passed through the dedicated bridge for LED lighting Power circuit. The method of claim 2, wherein the control unit, And a voltage level adjusting unit for adjusting a level of an output voltage determined according to a rated current of an LED lamp, which is a load, with respect to the voltage controlled by the valley voltage detector, the control pulse generator, and the switch. Circuit. As a power control method for LED lighting using a power circuit for LED lighting that controls the power for the LED lighting driven by AC power, The LED lighting power supply circuit includes a bridge rectifier for rectifying AC power and a capacitor charged by the current rectified by the bridge rectifier, Detecting a valley portion falling below a predetermined reference from the voltage waveform output through the bridge rectifier; And Controlling the electric current to be supplied to the LED to increase the voltage of the valley part by discharging the charge charged in the capacitor at the detected time point so that a constant current flows in the valley part; Power control method for the LED light comprising a. The method of claim 5, Detecting the valley portion, The voltage value outputted through the bridge rectifier is adjusted using a resistor to be the input voltage of the comparator, and the voltage drop begins to fall below the reference voltage at the input voltage by comparing a preset reference voltage with the input voltage of the comparator. Detecting a viewpoint, Controlling so that a constant current flows in the valley portion, Generating a pulse having a predetermined width at the detected falling time point; And causing the electric current to flow by increasing the voltage of the valley portion of the current waveform of the LED by discharging the electric charge charged in the capacitor at the valley voltage detection zero cross position as the control pulse is generated. Power control method for LED lighting.

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