KR20150031880A - Apparatus for active valley-fill circuit for driving light emitting diodes - Google Patents

Abstract

The present invention relates to an active valley-fill circuit for driving a light emitting diode. More particularly, the present invention relates to an apparatus for improving flicker characteristics and representing high light efficiency, a high power factor and low THD characteristics by applying an AC power direct linear type light emitting driver which does not use a converter. Since it is very difficult to improve a flicker without reducing a power factor in an existing AC power direct type light emitting diode driving scheme, a scheme of using the converter is widely used in a case of a lighting in which flicker characteristic is important. However, in a case of lighting using the converter, if a manufacturing cost is high and many components are used so that a system is large and heavy, reliability is relatively low. The present invention is aimed at maintaining an advantage of the AC power direct type linear light emitting diode driving scheme and improving flicker characteristics which was pointed out as a problem. The present invention may reduce a manufacturing costs of the whole lighting and reduce the size and weight and increase reliability while representing high light efficiency, a high power factor and low THD characteristics in an AC power direct type linear scheme by adding only a single capacitor and a single switch through an active valley-fill circuit for driving a light emitting diode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an active-type valley-fill circuit for driving a light-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active type valley-fill circuit for driving a light emitting diode, and more particularly, to an AC (direct current) direct current type linear LED driving apparatus using no converter, ) Characteristics and high luminous efficiency, high power factor and low THD (total harmonic distortion) characteristics. The present invention can be applied variously to driving a multi-channel LED having one or more channels.

Light emitting diodes are driven by converters that control current by using inductors and capacitors, such as SMPS (Switching Mode Power Supply), and currents by using commercial AC power directly without using SMPS And can be classified into an AC power direct type linear method. In the case of the converter method, the inductor and the capacitor, which are energy storage elements, are used so that a constant current can be supplied to the light emitting diode even in a region where the AC power supply voltage is low, so that flicker does not occur. However, in the case of the converter method, the configuration of the system is complicated and it is difficult to reduce the size and weight of the system. In addition, in the case of the converter method, a separate power factor correction circuit must be used to improve the power factor, and an additional circuit for suppressing the generation of electromagnetic waves generated at the time of switching is required.

On the other hand, direct-current type direct-current type linear power system has a merit of simpler circuit than the converter type because it controls the current by directly using the AC power source, which is a commercial power source.

1 shows a conventional linear driving circuit and input voltage and current. Flicker occurs because the input current does not flow during the period when the input is below the LED turn-on voltage, and the power factor is low and the THD is high. 2 shows input voltage and current characteristics in a multi-channel driving mode or a sequential driving mode, and shows improvements in power factor, THD and efficiency characteristics compared with the conventional method in which the driving is performed simultaneously using only one channel. However, in FIG. 2, as in FIG. 1, since the direct light emitting diode is driven using the AC power source, the light emitting diode is not driven when the voltage applied to the light emitting diode is lower than the voltage required for driving the light emitting diode. That is, the LED driving current does not flow at a cycle of 100 Hz or 120 Hz corresponding to twice the frequency of the AC power source, and a flicker corresponding to the frequency and duty of the driving current occurs. Most displays such as TVs and monitors are accompanied by flicker at 60 Hz, but there is an active trend to set more flicker regulations for LED lighting in recent years. The reason for the strengthening of regulations is that researchers report that exposure to long-term lighting can cause problems such as dizziness or seizures in sensitive people below 120 Hz. The greatest advantage of linear systems using direct AC power is the high reliability, lightweight and compact system and low manufacturing costs that come from the simplicity of the switching system versus the switching system. However, if the flicker characteristics required by the new regulations expected to be enacted in the future are not satisfied, the linear method will no longer be available for general illumination.

A passive valley-fill circuit that is widely used is a circuit that can prevent the power supply voltage from being lowered while maintaining a high power factor. Figure 3 shows the passive valley-fill circuit and output voltage characteristics. C ₁ and C ₂ is charged by the half of the maximum average rectified voltage to perform the operation in which the C ₂ If the AC voltage is low to drive the load. However, passive-type fill-in circuits are limited to only half of the maximum voltage, and when applied to linear-type light-emitting diode circuits, there are many limitations in controlling flicker, emission efficiency, and power factor.

In the present invention, a single capacitor and a single switch are used in a linear method that does not use a converter, and the active type that satisfies the characteristics of a flicker characteristic, a high light efficiency, and a high power factor, This is about the Valley fill circuit.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an active type valley-fill circuit which satisfies the characteristics of improved flicker characteristics, high light efficiency and high power factor in a conventional LED driving circuit.

According to an aspect of the present invention, there is provided an active valley-fill circuit for driving a light emitting diode, comprising: a rectifier for rectifying an _AC power source; A switch block connected to the (+) terminal of the rectifying part and including at least one transistor; A capacitor connected to the negative terminal of the switch block and the rectifying part; A voltage detector for detecting a voltage of the AC power source; A switching signal generator connected to the voltage detector for determining a turn-on timing of the switch block based on the detected voltage of the AC power source; A switch driver connected to the switch signal generator and driving the switch block; A light emitting diode block including at least one light emitting diode connected to the rectifying portion; And a light emitting diode driver for driving the light emitting diode block.

Here, the voltage detecting unit is formed by Y wiring of a resistor connecting the (+) terminal of the AC power source, the (-) terminal of the AC power source and the common voltage terminal, In proportion to the magnitude of the voltage.

The voltage detector may detect not only the AC voltage but also the voltage of the rectifying part or the voltage or current necessary for determining the switching timing from the LED driving part

The switching signal generator includes at least one of a comparator, a timer, and a counter, and generates a switching signal using at least one of the AC power supply voltage, the output of the rectifying unit, and the LED driving unit.

Further, the switch driving unit may further include a device for amplifying the switching signal and level-shifting the switching signal to drive the switching block.

In addition, the switch block may apply the voltage of the capacitor to the LED block according to at least the switching signal.

At this time, the switch block may include a switch composed of at least one P-type or N-type MOSFET and a diode connected in parallel to the switch.

The switch block may include a Darlington switch using a bipolar junction transistor (BJT) or a metal-oxide semiconductor field effect transistor (MOSFET), a cascode switch, an insulated gate bipolar transistor (IGBT) And a transistor (JFET).

In addition, the switching signal generator may include a comparator.

The capacitor unit may further include a capacitor and a device for limiting a current applied to the capacitor.

At this time, the device for limiting the current applied to the capacitor may include a resistor, a current source, an inductor, and a diode.

The active valley-fill circuit for driving a light emitting diode according to the present invention having the above-described configuration charges a capacitor when an input voltage is high and drives a light emitting diode with a voltage charged in a capacitor when an input voltage is low, The light emitting diode is driven with the high voltage stored in the capacitor to improve the flicker characteristic as well as increase the light efficiency. In addition, when the maximum current charged in the capacitor is limited by a resistor or an inductor, a higher power factor and a lower THD characteristic can be obtained.

There is an active movement to limit the production of low-frequency flickering lights, which are considered to have a bad influence on the human body. The present invention exhibits high power factor, high light efficiency and low THD characteristics while improving flicker characteristics, and has a simple structure of the entire system. As a result, the lighting system according to the present invention improves flicker characteristics without using an inductor or a transformer, achieves a high power factor, and does not require an EMI filter because there is no high frequency switching operation. The entire system is very simple, Feature.

Fig. 1 shows a driving circuit in an existing linear system, and an input voltage and an input current waveform.
FIG. 2 is a block diagram showing a conventional multi-channel or sequential driving type LED driving circuit using a linear method, and input voltage and input current waveforms.
3 is a block diagram showing the waveforms of the conventional passive-type fill-in circuit and the input voltage V _IN .
4 is a block diagram of an active type valley fill circuit for driving a light emitting diode of the present invention.
5 is a block diagram showing an active type valley-fill circuit using a P-type MOSFET as a switch of a valley fill circuit according to an embodiment of the present invention and applied to a light emitting diode drive circuit.
6 is a block diagram of a light emitting diode driving circuit using a resistor instead of the current source in FIG.
FIG. 7 is a circuit diagram illustrating a method of reducing the turn-off time of currents I _{LED, F} flowing through the LEDs by connecting capacitors C _{LED, F} for filtering the current flowing in the LEDs in parallel with the LEDs in FIG. Fig.
8 is a block diagram of an active valley-fill circuit using a P-type MOSFET as an embodiment of the present invention applied to a 4-channel LED driver circuit.
FIG. 9 is a waveform for explaining the operation of the active valley fill circuit for driving the light emitting diode of the present invention. The AC voltage V _AC , the gate voltage V _GATE , the input voltage V _IN , And shows the characteristics of the capacitor voltage (V _C ).
Figure 10 is a characteristic of the input voltage (V _IN), the input current (I _IN) and the LED current (I _LED) in Fig. 5 as a waveform for explaining the operation of the active valley fill circuit for the LED driving of the present invention .
Figure 11 is an active valley input voltage in FIG. 7 as a waveform for explaining the operation of the filter circuit (V _IN), the input current (I _IN) and the filtered light-emitting diode current (I _LED for the LED driving of the present _{invention, F} ).
12 is a waveform chart for explaining the operation when the active valley-fill circuit of the present invention is applied to a 4-channel LED driving circuit. In FIG. 12, the input voltage V _IN is V _LED1 <V _IN <V _LED1 + V _LED2 by turning on a switch in the range indicates the input voltage (V _iN), the input current _{(I iN), I LED1 ~} I LED4, and I _LED characteristics when supplied with a voltage (V _iN) input to the voltage stored in the valley fill capacitor .
FIG. 13 is a waveform _chart for explaining the operation when the active valley-fill circuit of the present invention is applied to a 4-channel LED driving circuit. In FIG. 13, the input voltage is V _LED1 + V _LED2 <V _IN <V _LED1 + V _LED2 + V _LED3 range of input voltage when the turn-on the switch in the supply to the voltage (V _iN) input to the voltage stored in the valley fill capacitor (V _iN), the input current _{(I iN), I LED1 ~} I LED4, and I _LED characteristics .
FIG. 14 is a circuit diagram illustrating an embodiment of the present invention in which a resistor is added in series with a capacitor to limit the instantaneous overcurrent generated in the capacitor during charging and to delay the charging current. A diode connected in parallel with the resistor serves to reduce the losses in the resistor during discharging.
15 shows a circuit for limiting the instantaneous overcurrent of a capacitor to a current source instead of a resistance according to an embodiment of the present invention.
FIG. 16 shows a circuit for limiting an instantaneous overcurrent of a capacitor, as well as an instantaneous overcurrent that may occur during driving of a light emitting diode, using an inductor according to an embodiment of the present invention.
17 shows a circuit for limiting the instantaneous overcurrent of a capacitor using an inductor according to an embodiment of the present invention. And discharging current through the diode to reduce the delay time due to the inductor.
FIG. 18 shows an example in which a digital circuit such as a timer or a counter is applied to detect an _AC power supply voltage (V _AC ) in setting a switching timing of a switch according to an embodiment of the present invention.
FIG. 19 shows an example in which the input voltage V _IN is detected and a digital circuit such as a timer or a counter is applied in setting the switching timing of the switch according to the embodiment of the present invention.
FIG. 20 shows an example in which one or more LED voltages are detected in setting a switch timing when a light emitting diode is driven by a current source according to an embodiment of the present invention, and a switching timing is determined based on the detected LED voltage.
FIG. 21 shows an example in which one or more LED voltages are detected in setting a switch timing when a light emitting diode is driven by a resistor in accordance with an embodiment of the present invention, and switching timing is determined based on the detected LED voltage.
Figure 22 is using the I LED voltage of one or more as a switch when driven at a constant current of a light emitting diode as an embodiment of the present invention using a transistor and a resistance setting the change timing, or through the resistance detecting I _LED current it And the switching timing is determined based on the reference.
FIG. 23 is a graph showing the relationship between the current I _LED current and the current I _LED current when the light emitting diode is driven by a constant current using a transistor, a resistor, and an OP amplifier in the embodiment of the present invention. And determines the switching timing based on the detection result.
FIG. 24 is a diagram illustrating an example in which the switching timing is determined based on the detection of the I _LED current by the resistance or other current detection method in setting the switch timing of the method of sequentially driving the multi-channel LEDs according to the embodiment of the present invention .
FIG. 25 illustrates an example in which one or more LED voltages are detected and the switching timing is determined on the basis of the detected one or more LED voltages in setting the switching timing of the method of sequentially driving the multi-channel LEDs according to the embodiment of the present invention.
FIG. 26 shows an embodiment in which a P-type MOSFET (MOSFET) is used as a switch in FIG. 4 and a capacitor and a switch are shifted from each other in position.
FIG. 27 shows an embodiment in which an N-type MOSFET (MOSFET) is used as a switch in FIG.
Fig. 28 shows an embodiment in which the positions of the switches and the capacitors are changed in Fig.
FIG. 29 shows an embodiment in which two P-type MOSFETs are used as bidirectional switches in FIG.
Fig. 30 shows an embodiment in which the position of the bi-directional switch and the capacitor are changed in Fig.
FIG. 31 shows an embodiment in which two N-type MOSFETs are used as bidirectional switches in FIG.
FIG. 32 shows an embodiment in which the positions of the bidirectional switch and the capacitor are changed in FIG.

The preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which the technical parts already known will be omitted or compressed for simplicity of explanation.

The present invention can be applied to a single channel of a light emitting diode. The present invention can also be applied to a two-channel or more multi-channel sequential driving method in order to obtain an improved flicker characteristic, a high power factor and a low THD characteristic.

4 is a block diagram for explaining an active type valley fill circuit for driving a light emitting diode of the present invention. 4, the active valley-fill circuit 100 includes a rectifying part 110 for rectifying an _AC power source V _AC , a switch block 120 connected to the positive terminal of the rectifying part and including at least one transistor, A capacitor connected to the switch block and a negative terminal of the rectifying part, a voltage detector for detecting a voltage of the AC power source, and a voltage detector connected to the voltage detector for detecting the voltage of the AC power source A switch signal generator 150 for determining a turn-on timing of the switch block 120, and a switch driver 160 connected to the switch signal generator and driving the switch block. Meanwhile, since the capacitor 130 may be composed of a single element C, the capacitor 130 will be described as a capacitor C hereinafter.

Figure 5 shows that the LED driver is driven by a minimum component that implements the active valley-fill circuit according to the present invention. 5, the LED driver is composed of a 1-channel LED and a current source, but the present invention is not limited to the configuration of the LED driver, and the LED driver can be variously configured according to the embodiment.

5, the voltage detector 140 includes resistors R ₁ and R ₂ for connecting the (+) terminal of the AC power source, the (-) terminal of the AC power source and the common voltage terminal , R ₃ ). The voltage detector 140 proportionally decreases the voltage of the AC power source regardless of the output voltage of the rectifier 110.

When connecting a resistor to the input voltage (V _IN) for detecting a voltage, but the change in the voltage (V _C) when the switch (SW) is turned on, the input voltage (V _IN) is stored in the capacitor (C), the voltage of the present invention Since the detecting unit 140 is directly connected to the positive terminal of the AC power source, the negative terminal of the AC power source, and the common voltage terminal, the detecting unit 140 can detect the voltage of the AC power source as it is even when the switch SW is turned on.

The switching signal generator 150 determines when the switch SW is turned on based on the detected voltage of the AC power source. According to the embodiment, the switching signal generator 150 may be composed of a simple comparator or an OP amplifier. When the voltage detector 140 is configured to directly detect the voltage of the AC power source, although the switch SW is turned on, the voltage detector 140 does not influence the input voltage V _IN The input voltage to be measured fluctuates due to the voltage charged in the capacitor C when the switch SW is turned on. Therefore, in this case, when the switching signal generator 150 is composed of only a simple comparator, a voltage detection error may occur. Therefore, in this case, the switching signal generator 150 may further include a compensation circuit such as a timer or a counter to compensate for the voltage detection error.

The switch driving unit 160 may be configured to directly drive the switch SW according to the configuration of the switch block 120 and may further include a device for level shifting the switching signal according to the type of the transistor constituting the switch block 120 .

Switch block 120 is a voltage (V _C) charging the capacitor (V _IN) into a node of the input voltage when the charge to the input voltage (V _IN) to the capacitor (C) and also reduces the input voltage (V _IN) Supply. When the voltage V _{C of the} capacitor C is lower than the input voltage V _IN , the capacitor C is charged through the diode D ₁ .

FIG. 6 is an example of driving an LED driver in which an active-type valley-fill circuit according to the present invention is composed of a one-channel LED and a resistor. Referring to FIG. 6, the current flowing through the LED increases as the input voltage V _IN increases.

FIG. 7 shows an example in which the LED driver of FIG. 5 further includes a capacitor C _{LED, F.} FIG. 7, the LED driver can be driven by the capacitors C _{LED, F} even when the input voltage V _IN is not applied to the LED driver or when the supply of current from the capacitor C is temporarily stopped.

8 is an example in which the active valley-fill circuit according to the present invention drives a four-channel LED driver.

FIG. 9 is a graph for explaining the operation state of the active valley fill circuit of the present invention. FIG. 9 is a graph showing a steady-state in which the operation of turning on the switch SW is repeated when the input voltage V _IN is equal to or lower than a predetermined voltage. (V _AC ), a switch driving gate voltage (V _GATE ), an input voltage (V _IN ), and a capacitor voltage (V _C ).

By a parallel connected diode (D ₁₎ in the P- type MOSFET switch (Q _1), the capacitor (C) is a capacitor (C) voltage (V _C) input voltage (V _IN) is lower than if the capacitor voltage (V _C of Is always equal to the input voltage V _IN . On the other hand, the input voltage (V _IN) is when a predetermined voltage or less is a switch (Q ₁₎ driven by the switching signal generator, a capacitor (C) comes into the discharge thus light emission even at a low input voltage (Q ₁₎ period diode Can be supplied with a high voltage capable of driving.

The capacitor voltage dropped while the capacitor drives the light emitting diode is charged up to the maximum value again at the next input voltage rise of the AC power supply (V _AC ).

The input voltage to start charging at this time can be calculated from the following equation.

Vcharge = Vpeak - Q / C = Vpeak - Ic, avg.times.t / C

where Vcharge = input voltage to start charging

Vpeak = instantaneous maximum value of input voltage

Ic, avg = Average current supplied by the capacitor to the light emitting diode

ton = switch turn-on time

C = Capacitance

As can be seen from the above equation, the charging time of the capacitor depends on the size of the capacitor, the amount of current and time of the LED supplied by the capacitor. As a result, if the size of the capacitor C corresponding to the light emitting diode output is selected, the active valley fill can be supplied with a sufficient current LED during the time the circuit operates.

10 is a graph for explaining the operation state of the active valley fill circuit of the present invention. The steady-state operation repeats the operation of turning on the switch SW when the input voltage V _IN is a certain voltage or less. (V _IN ), an input current (I _IN ), and a light emitting diode current waveform.

Since the active valley fill supplies the capacitor voltage up to twice as high as the passive type, the light emitting diode can maintain a sufficient turn-on state during the supply of the valley voltage. In addition, the current charged in the capacitor as the input voltage rises is combined with the LED driving current to become the input current. As a result, as shown in the drawing, the current charged in the capacitor appears in a form that does not compromise the power factor and THD of the input current.

Further, as shown in FIG. 14 to FIG. 17, when the maximum charge current of the capacitor is limited by using a resistor, a current source or an inductor, a higher power factor and THD characteristics can be obtained. When the maximum value of the charging current of the capacitor is limited, the capacitor charging current can be shifted to the maximum value of the input voltage by the current delay effect, and the power factor can be further increased. However, the maximum voltage charged in the capacitor can be reduced in proportion to the delay.

FIG. 11 is a view for explaining the operation of FIG. 7. FIG. 11 is a graph for explaining the operation of FIG. 7, in which the input voltage V _IN , the input current I _IN , and the light emitting diode current waveform in a steady state when a capacitor is connected in parallel to the light emitting diode .

It can be seen that the current of the light emitting diode is maintained by the capacitor serving as the filter without completely decreasing. Therefore, it can be seen that the flicker is improved.

FIG. 12 is a view for explaining an active-type valley-fill circuit for driving a multi-channel LED according to the present invention. When the turn-on time of the valley-fill switch in the 4-channel driving of FIG. 8 is defined as the interval between the turn- The input voltage V _IN , the input current I _IN , I _LED1 through IL _ED4, and the I _LED waveform in the state of FIG. During the time that the valley voltage is supplied, all the light emitting diodes are in a state of passing the set maximum current, and as a result, I _LED1 is always turned on, so that the entire LEDs are not turned off. In addition, the input current has a value of " 0 &quot; in a period in which the capacitor turns on and supplies a current in which the current of the LED and the capacitor is summed in a period in which the capacitor is charged.

FIG. 13 is a diagram for explaining an active-type valley-fill circuit for driving a multi-channel LED according to the present invention. In the case of driving the four-channel drive of FIG. 8 between the turn- The input voltage V _IN , the input current I _IN , I _LED1 through IL _ED4, and the I _LED waveform in the state of FIG. Since the valley voltage is applied at the time when I _LED2 is turned on, I _LED1 and I _LED2 are always turned on throughout the whole area, so that more LEDs are always turned on than in Fig. I Since _LED1 is always turned on, the driving part of LED1 becomes unnecessary, and it is possible to obtain the effect of driving four channels with three channels. I _LED1 and _I2 show that the flicker characteristics can be further improved because they are always on throughout the entire _duration . However, the input current width is narrowed and the maximum value is increased as compared with FIG. 12, so that the power factor and the THD are reduced. That is, it can be seen that there is a trade-off relationship between flicker, power factor and THD.

As mentioned above, by limiting the charge current applied to the capacitor C, a higher power factor can be obtained.

FIG. 14 is a circuit diagram illustrating an operation of limiting and delaying an instantaneous overcurrent generated in a capacitor during charging by adding a resistor in series with a capacitor according to an embodiment of the present invention.

A diode connected in parallel with the resistor serves to reduce the losses in the resistor during discharging.

15 shows a circuit for limiting the instantaneous overcurrent of a capacitor to a current source instead of a resistance according to an embodiment of the present invention.

FIG. 16 shows a circuit for limiting an instantaneous overcurrent of a capacitor, as well as an instantaneous overcurrent that may occur at the time of driving a light emitting diode, using an inductor according to an embodiment of the present invention.

17 shows a circuit for limiting the instantaneous overcurrent of a capacitor using an inductor according to an embodiment of the present invention. And discharging current through the diode to reduce the delay time due to the inductor.

If the charge current of the capacitor is lowered by using the resistor R ₄ , the inductor L ₁ , the diode D ₂ and the current source I ₁ and the charge current is delayed, a higher power factor is obtained Can be obtained.

FIG. 18 shows an example in which the input AC voltage V _AC is detected and a digital circuit such as a timer or a counter is applied in setting the switching timing of the switch according to the embodiment of the present invention.

FIG. 19 shows an example in which the input voltage V _IN is detected and a digital circuit such as a timer or a counter is applied in setting the switching timing of the switch according to the embodiment of the present invention.

FIG. 20 shows an example in which one or more LED voltages are detected in setting a switch timing when a light emitting diode is driven by a current source according to an embodiment of the present invention, and a switching timing is determined based on the detected LED voltage.

FIG. 21 shows an example in which one or more LED voltages are detected in setting a switch timing when a light emitting diode is driven by a resistor in accordance with an embodiment of the present invention, and switching timing is determined based on the detected LED voltage.

Figure 22 is using the I LED voltage of one or more as a switch when driven at a constant current of a light emitting diode as an embodiment of the present invention using a transistor and a resistance setting the change timing, or through the resistance detecting I _LED current it And the switching timing is determined based on the reference.

FIG. 23 is a graph showing the relationship between the current I _LED current and the current I _LED current when the light emitting diode is driven by a constant current using a transistor, a resistor, and an OP amplifier in the embodiment of the present invention. And determines the switching timing based on the detection result.

FIG. 24 is a circuit diagram illustrating a method of driving a multi-channel LED according to an embodiment of the present invention. In the case of driving the multi-channel LEDs sequentially, the I _LED current is detected by a resistance or another current detection method in setting the switch timing, Is determined.

FIG. 25 shows an example in which one or more LED voltages are detected in setting the switch timing when the multi-channel LEDs are sequentially driven using the method of the present invention, and the switching timing is determined based on the detected LED voltages .

FIG. 26 shows an embodiment in which a P-type MOSFET (MOSFET) is used as a switch in FIG. 4 and a capacitor and a switch are changed in position.

FIG. 27 shows an embodiment in which an N-type MOSFET (MOSFET) is used as a switch in FIG.

Fig. 28 shows an embodiment in which the positions of the switches and the capacitors are changed in Fig.

FIG. 29 shows an embodiment in which two P-type MOSFETs are used as bidirectional switches in FIG.

Fig. 30 shows an embodiment in which the position of the bi-directional switch and the capacitor are changed in Fig.

FIG. 31 shows an embodiment in which two N-type MOSFETs are used as bidirectional switches in FIG.

FIG. 32 shows an embodiment in which the positions of the bidirectional switch and the capacitor are changed in FIG.

The power factor and the THD can be improved by limiting the maximum charge current by combining a resistor, a current source, and an inductor in the same way for all methods using a unidirectional switch or a bidirectional switch.

The transistors used in the above description and drawings are represented by MOSFETs, and general transistors are expressed in parentheses. In addition, the transistors usable in the present invention include an insulating gate bipolar transistor (IGBT), a junction type transistor (BJT), a junction type electric field (BJT), and the like, including use in a Darlington and Cascode form using a BJT and a MOSFET And an effect transistor (JFET).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. And the scope of the present invention should be understood as the following claims and their equivalents.

100: Active valley fill circuit
110: rectification part
120: Switch block
130: Capacitor
140:
150: Switching signal generator
160:

Claims (32)

A rectifying section for rectifying the AC power supply voltage;
A switch block connected to the (+) terminal of the rectifying part and including at least one transistor;
A capacitor connected to the negative terminal of the switch block and the rectifying part;
A voltage detector for detecting a voltage of the AC power source;
A switching signal generator connected to the voltage detecting unit and determining a turn-on timing of the switch block based on the detected AC power supply voltage; And
And a switch driver connected to the switch signal generator and driving the switch block. The method according to claim 1,
Wherein the switch block comprises a switch comprising a P-type MOSFET and a diode connected in parallel to the switch. The method according to claim 1,
Wherein the voltage detecting section is formed by Y wiring of a resistor connecting a (+) terminal of the AC power source, a (-) terminal of the AC power source and a (-) terminal of the rectifying section, An active valley-fill circuit for driving a light-emitting diode that detects the voltage magnitude of an alternating current power source in a proportional manner.
The method of claim 3,
Wherein the voltage detecting unit further detects a terminal voltage of the rectifying unit. The method according to claim 1,
The switching signal generator
A comparator, a timer, and a counter,
And a switching signal for driving the switch block is generated by using at least one of the voltage of the AC power source measured by the voltage detector and the terminal voltage of the rectifying part. The method according to claim 1,
Wherein the switch driver further comprises a device for amplifying or level shifting the switching signal. The method according to claim 1,
And the switch block outputs the voltage of the capacitor by the switching signal. The method according to claim 1,
The switch block may be a Darlington switch using a bipolar junction transistor (BJT) or a metal-oxide semiconductor field effect transistor (MOSFET), a switch of a cascode type, an insulated gate bipolar transistor (IGBT) An active valley fill circuit for driving a light emitting diode comprising at least one switch made up of an effect transistor (JFET). The method according to claim 1,
Wherein the switching signal generator includes a comparator and an operational amplifier. The method according to claim 1,
(-) terminal of the rectifying unit and the capacitor,
And an element for limiting a current applied to the capacitor. The method of claim 10,
An active valley fill circuit for driving a light emitting diode, comprising: a diode; a resistor; an inductor; and a current source. The method according to claim 1,
(+) Terminal of the rectifying unit,
And an element for limiting a current applied to the capacitor. The method of claim 12,
An active valley fill circuit for driving a light emitting diode, comprising: a diode; a resistor; an inductor; and a current source. The method according to claim 1,
The active Valley fill circuit for driving the light emitting diode
And a plurality of LEDs connected between the (+) terminal and the (-) terminal of the rectifying section and an LED driving section for driving the LEDs. 15. The method of claim 14,
Wherein the LED driving unit drives a light emitting diode using a current source or a resistor. 15. The method of claim 14,
Wherein the LED driving unit forms a current source using a transistor and a resistor and drives the light emitting diode. 18. The method of claim 16,
Wherein the LED driver includes an operational amplifier to improve characteristics of a current source to drive the LED. The method according to claim 1,
The active Valley fill circuit for driving the light emitting diode
And a plurality of LEDs connected between the (+) terminal and the (-) terminal of the rectifying unit and an LED driver for driving the LEDs,
Wherein the voltage detecting unit further detects at least one of a voltage of each of the plurality of LEDs and a voltage of the LED driving unit. The method according to claim 1,
The active Valley fill circuit for driving the light emitting diode
And a multi-channel LED connected between the (+) terminal and the (-) terminal of the rectifying section and a multi-channel LED driver sequentially driving the multi-channel LED. The method of claim 19,
Wherein the voltage detecting unit further detects at least one of a voltage of each of the multi-channel LEDs and a voltage of the LED driving unit. A rectifying section for rectifying the AC power supply voltage;
A switch block connected to the negative terminal of the rectifying part and including at least one transistor;
A capacitor connected to the switch block and a (+) terminal of the rectifying part;
A voltage detector for detecting a voltage of the AC power source;
A switching signal generator connected to the voltage detecting unit and determining a turn-on timing of the switch block based on the detected AC power supply voltage; And
And a switch driver connected to the switch signal generator and driving the switch block. 23. The method of claim 21,
Wherein the switch block comprises a switch comprising an N-type MOSFET and a diode connected in parallel to the switch. The method according to claim 1,
The switch block is an active-type valley-fill circuit for driving a light-emitting diode that performs bidirectional switch operation using two P-type MOSFETs. 23. The method of claim 21,
The switch block is an active-type valley-fill circuit for driving a light-emitting diode that performs bidirectional switch operation using two P-type MOSFETs. 23. The method of claim 21,
Wherein the switch block is a bi-directional switch using two N-type MOSFETs. 23. The method of claim 21,
Wherein the voltage detecting section is formed by Y wiring of a resistor connecting a (+) terminal of the AC power source, a (-) terminal of the AC power source and a (-) terminal of the rectifying section, An active valley-fill circuit for driving a light-emitting diode that detects the voltage magnitude of an alternating current power source in a proportional manner. 23. The method of claim 21,
Wherein the voltage detecting unit further detects a terminal voltage of the rectifying unit. 23. The method of claim 21,
The switching signal generator
A comparator, a timer, and a counter,
And a switching signal for driving the switch block is generated by using at least one of the voltage of the AC power source measured by the voltage detector and the terminal voltage of the rectifying part. 23. The method of claim 21,
Wherein the switch driver further comprises a device for amplifying or level shifting the switching signal. 23. The method of claim 21,
The active Valley fill circuit for driving the light emitting diode
And an element for limiting a current applied to the capacitor. 32. The method of claim 30,
An active valley fill circuit for driving a light emitting diode, comprising: a diode; a resistor; an inductor; and a current source. 23. The method of claim 21,
The active Valley fill circuit for driving the light emitting diode
And a plurality of LEDs connected between the (+) terminal and the (-) terminal of the rectifying unit, and an LED driver for driving the LEDs,
Wherein the voltage detecting unit further detects at least one of a voltage of each of the plurality of LEDs and a voltage of the LED driving unit.

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