KR101792978B1 - LED Power Supply - Google Patents

Abstract

An LED power supply device according to the present invention comprises: an input terminal rectifying diode (20); a first winding wire (301); a main switch (306); first and second voltage-dividing capacitors (304, 305); a second winding wire (302); a switch (307); an output diode (308); a third winding wire (303); a plurality of LED groups (41, 42, 43); a constant current control unit (501); and a variable frequency control unit (502). The first winding wire (301), the second winding wire (302), and the third winding wire (303) are wound on one core. The constant current control and the power factor improvement can be simultaneously performed.

Description

LED Power Supply {LED Power Supply}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED (Light Emitting Diode) More specifically, the present invention relates to an LED power supply device having a constant current control unit 501 for LED and a variable frequency control unit 502 for power factor correction, and capable of simultaneously performing constant current control and power factor improvement will be.

Recently, LED lighting devices have been used for a variety of lighting in indoor and outdoor due to their long life and high efficiency. Generally, 10 to 12 LEDs are connected in series in a group of LEDs, and it is generally controlled by a constant current. It is also common to control a plurality of LED groups (Group 41, 42, 43) by a single converter or a plurality of converters. When a particular LED is destroyed in a group of 10 to 12 LEDs connected in series, the destroyed LED is shorted and the remaining LEDs continuously emit light, .

1 and 2 show a LED street lamp head portion and a tunnel head portion where the LED module is disposed. In general, two to eight LED groups (10 to 12 individual LEDs connected in series) are generally arranged on the heads of the LED street lamp head and the head of the tunnel.

FIG. 3 and FIG. 4 show an apparatus for emitting a plurality of LED groups (Groups 41, 42 and 43) controlled by a conventional single-stage converter 31. The AC power source 10 is supplied through the AC power source 10 and the input rectifier diode 20 and the first, second and third LED groups (Group 41) 41 are connected via the single- , 42, 43), and the like. FIG. 3 is a circuit for emitting a plurality of LED groups connected in series, and FIG. 4 is a circuit for emitting a plurality of LED groups connected in parallel. The advantage of the plurality of LED groups (Groups 41, 42, 43) controlled by a single converter as shown in FIGS. 3 and 4 is that the first, second and third LED groups (groups 41, 43, and the like.

Figure 5 shows a conventional single power stage LED power supply. The single power stage LED power supply device of FIG. 5 performs constant current control on a plurality of LED groups (Groups 41, 42 and 43), and performs power factor correction at the same time. When the main switch 23 of the power factor improving circuit unit is turned on, a current is conducted as follows.

- current path 1: step-up inductor (22) - second diode (25) - main switch (23) of the power factor improvement circuit part

The main switch 23 of the power factor correction circuit part is connected to the first power supply circuit 22,

Because of the current path 1 and the current path 2, energy is magnetically stored in the step-up type inductor 22 and the main transformer 30. In particular, the power factor of the input stage is improved by operating the step-up type inductor 22 through the current path 1 in a discontinuous currnet mode (DCM).

Because of the current path 2, energy is magnetically stored in the main transformer 30. The energy stored in the main transformer 30 at the time of turning off the main switch 23 of the power factor correction circuit part is supplied to the plurality of LED groups (Group 41, 42, 43) .

5, the main switch 23 of the power factor correction circuit unit must simultaneously control the constant current of the LED and the power factor of the input power source. Therefore, voltage stress of the main switch 23 of the power factor improving circuit portion is high and the power factor can not be improved at the same time.

6 and 7 show a boost power factor improving circuit part 21 for improving the power factor and a plurality of boost power factor improving circuit parts 21 are provided at the rear end of the booster power factor improving circuit part 21, A plurality of LED groups (Group 41, 42, 43) are controlled by disposing a DC-DC converter.

However, since the circuit of Figs. 5 and 6 disposes the booster power factor improving circuit 21 and the DC-DC converter at the rear stage, the device for supplying the entire LED power is complicated, There is a drawback that the price is significantly increased because it is necessary.

There are prior art references relating to the power supply for LEDs as follows.

[Patent Document 1] U.S. Patent No. 6577512, Published on Jun. 10, 2003. [Patent Document 2] Korean Patent Laid-Open Publication No. 10-2014-0043865, Publication Date 2014.04.11. Patent Document 1 discloses a flyback converter for emitting an LED and a power supply for an LED capable of current control using the flyback converter. [Patent Document 2] discloses a DC power supply device having a simple circuit configuration for emitting an LED.

The present invention proposes an LED power supply capable of simultaneously controlling a constant current by a single power stage and simultaneously improving power factor. In this way, the power supply device can effectively perform the power factor correction control simultaneously with the constant current control with a single power stage.

The LED power supply apparatus proposed in the present invention is characterized in that there are a main switch 306 for constant current control and a switch 307 for power factor improvement, respectively. The main switch 306 for the constant current control performs duty control and the switch 307 for power factor improvement performs variable frequency control. Further, since the first, second and third windings 301, 302, and 303 are disposed in one core using the coupling inductor, there is an advantage that the number of inductors of the power supply device is reduced as much as possible. Accordingly, it is an object of the present invention to provide an LED power supply capable of effectively performing constant current control and power factor correction with a single power stage.

In the present invention, there is an effect of providing a constant current control and a high power factor power source device with a single power stage in an LED power source device. This effectively emits a plurality of LED groups (Group 41, 42, 43), reduces the reactive current, and increases the high power factor.

Fig. 1 is a cross-sectional view of a LED street lamp head,
Fig. 2 is a cross-sectional view of a head portion of an LED tunnel,
FIG. 3 is a circuit diagram illustrating a circuit for emitting a plurality of LED groups (Group)
FIG. 4 is a circuit diagram of a circuit for emitting a plurality of LED groups (Group)
5 is a circuit diagram of a circuit for emitting a plurality of LED groups (Group) with a single power stage converter
6 is a circuit (a parallel operation of the first, second and third converters at the stage after the booster power factor improving circuit portion) for emitting a plurality of LED groups (Group) by a plurality of converters and a plurality of controllers,
7 is a circuit for emitting a plurality of LED groups (Group) by a plurality of converters and a plurality of controllers (the primary side of the main transformer 30 has a power factor improving circuit portion for performing a power factor improving function, and the main transformer 30 3 < / RTI >< RTI ID = 0.0 > buck converter < / RTI &
Figure 8 shows the proposed LED power supply
9 shows the proposed LED power supply and the detailed control circuit
Figure 10 is a schematic diagram of the coupling inductor
11 shows a first controller type (detailed embodiments of the third, fourth, fifth, and sixth control gain determinants Z3, Z4, Z5, and Z6)
12 shows a second controller type (detailed embodiments of the third, fourth, fifth, and sixth control gain determinants Z3, Z4, Z5, and Z6)
13 shows a third controller configuration (detailed embodiments of the third, fourth, fifth, and sixth control gain decision sections Z3, Z4, Z5, and Z6)
14 shows a fourth controller type (detailed embodiment of the first and second control gain determinants Z1 and Z2)

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 8 shows the proposed LED power supply. In Fig. 8, a power supply device which is most suitable for constant current control and power factor improvement is proposed. The first, second, and third windings 301, 302, and 303 of the coupling inductor are wound on a single inductor core. The first winding 301 of the coupling inductor functions as an inductor for improving the power factor at the input stage. One end of the first winding 301 of the coupling inductor is connected to the positive terminal of the input stage rectifier diode 20 and the other end of the first winding 301 of the coupling inductor is connected to the positive To the main switch 306 and the first voltage-dividing capacitor 304, respectively. The first divided capacitor 304 and the second divided capacitor 305 function to divide the rectified input power and the connection point of the first divided capacitor 304 and the second divided capacitor 305 is connected to the output terminal of the coupling inductor And is connected to one end of the two windings 302. The other end of the second winding 302 of the coupling inductor is connected to one end of a switch 307 for improving the power factor and an anode of the output diode 308. The cathode of the output diode 308 is connected to the other end of the main switch 306 for constant current control and is connected to one end of the third winding 303 of the coupling inductor Respectively.

The proposed LED power supply of FIG. 8 does not have an output capacitor to perform a constant current control, and a plurality of LED groups (Group 41, 42, 43) are directly connected to the third winding 303 of the coupling inductor It is a technical feature to be connected. 8, the main switch 306 for controlling the constant current and the switch 307 for improving the power factor are respectively provided. The first current sensor 51 detects the current of the plurality of LED groups (Group 41, 42, 43) And controls the main switch 306 by performing a duty control by the constant current control unit 501. [ The fourth current sensor 55 detects the current information of the input stage rectifier diode 20 and controls the frequency of the switch 307 for improving the power factor by the variable frequency controller 502 .

9 shows a proposed LED power supply and a detailed control circuit.

The characteristics of a general operational amplifier (OP-Amp) will be described below to explain FIG.

The operational amplifier OP-Amp has a (+) terminal and a negative terminal, and amplifies the signal to the output terminal according to the comparison of the (+) terminal and the (-) terminal signal. The ideal operational amplifier (OP-Amp) is characterized in that (1) the input terminal impedance is infinite, and (2) the output terminal impedance is zero. When information is input to the (+) terminal, the amplification ratio of the operational amplifier is (+), but when the information is input to the (-) terminal, the amplification ratio of the operational amplifier is (-). In addition, an operational amplifier (OP-Amp) having a hysteresis characteristic functions as a comparator. That is, the hysteresis characteristic means that the output voltage of the operational amplifier OP-Amp is outputted as the maximum or minimum operating voltage of the operational amplifier OP-Amp. If the operating voltage of the hysteresis OP-Amp is 15 [V], the hysteresis operational amplifier outputs +15 [V] and -15 [V], and the operation of the hysteresis operational amplifier (Hysteresis OP-Amp) When the voltage is 5 [V], the hysteresis operational amplifier outputs +5 [V] and -5 [V].

The detailed operation of FIG. 9 will be described based on the characteristics of the operational amplifier OP-Amp and the hysteresis operational amplifier (Hysteresis OP-Amp). The constant current control unit 501 is a current control unit for comparing the output current information of the first current sensor 51 for detecting the current of the plurality of LED groups (Groups 41, 42 and 43) with the output current reference value Ioref And an operational amplifier (OP-AMP) 531 are disposed.

When a large amount of current flows through the plurality of LED groups (Group 41, 42, 43) than the output current reference value Ioref, the current control operational amplifier OP-AMP 531 generates a negative voltage (-) voltage is generated in the current control operational amplifier (OP-AMP) 531, the second control power supply Vcc2 operates the photo-coupler 551, and the third control power supply Vcc2 operates the third (OP-AMP) 531 through a diode 534 to the output terminal of the operational amplifier (OP-AMP) The receiver of the photocoupler 551 receives the signal from the power supply of the first control power supply Vcc1 and outputs the output of the constant current control operational amplifier OP-AMP 521 of the constant current controller 520 To generate the control voltage Vc. The control voltage Vc is compared with the sawtooth voltage Vm through a pulse width modulation operational amplifier (OP-AMP) 511 to control the main switch 306 for constant current control.

The fourth current sensor 55 detects current information of the input stage rectifier diode 20 for variable frequency control of the switch 307 for power factor correction. The hysteresis operational amplifier OP-AMP 541 compares the current information of the input rectifier diode 20 and the input current reference value Icref. The hysteresis operational amplifier (OP-AMP) 541 generates the output voltage in the positive direction when the current of the input stage rectifier diode 20 exceeds the input current reference value Icref. When the output voltage of the hysteresis operational amplifier (OP-AMP) 541 is positive, the N-type transistor 545 is operated and the resistance input to the RT terminal of the oscillator (OSC) 547 are changed so that the second resistor 546 and the third resistor 547 are connected in parallel. That is, when the output voltage of the hysteresis operational amplifier (OP-AMP) 541 is positive, the resistance value of the RT terminal of the oscillator (OSC) 548 is reduced by the operation of the N-type transistor 545 , The frequency of the oscillator (OSC) 548 decreases. In the RS flip-flop 550, the control voltage Vc and the voltage of the oscillator (OSC) 548 are supplied to vary the frequency.

Therefore, the frequency of the switch 307 for improving the power factor is varied through the variable frequency control unit 502. When the current of the input stage rectifier diode 20 is high, the frequency of the switch 307 for improving the power factor is increased. The frequency of the switch 307 for improving the power factor is lowered when the current of the input stage rectifier diode 20 is low.

FIG. 10 shows a detailed implementation of the coupling inductor of the proposed LED power supply device, in which the first, second and third windings 301, 302 and 303 are arranged in one core.

Figs. 11 to 13 are detailed embodiments of the third, fourth, fifth, and sixth control gain determinants Z3, Z4, Z5, and Z6 in the form of first to third controllers, Can be applied.

FIG. 14 shows a detailed embodiment of the first and second control gain determinants Z1 and Z2 as a fourth controller type, and generates two pole points and one zero controllably in a controlled manner, .

In the present invention, in the LED power supply device,

An input stage rectifier diode 20 for rectifying the AC power source 10; A first winding (301) of a coupling inductor disposed at a positive output terminal of the input stage rectification diode (20); A main switch 306 for constant current control connected to the other end of the first winding 301 of the coupling inductor; First and second voltage dividing capacitors 304 and 305 connected to the other end of the first winding 301 of the coupling inductor and the drain terminal of the main switch 306 to divide the voltage; A second winding (302) of a coupling inductor coupled to the contacts of the first and second voltage dividing capacitors (304, 305); A switch 307 for improving power factor disposed between the other end of the second winding 302 of the coupling inductor and the negative power terminal; An output diode 308 connected to the drain terminal of the switch 307 for improving the power factor and the other end of the second winding 302 of the coupling inductor; A third winding 303 of a coupling inductor coupled to an anode terminal of the output diode 308 and a source terminal of the main switch 306 for constant current control; A plurality of LED groups (Groups 41, 42, 43) disposed between the other end of the third winding 303 of the coupling inductor and the negative power terminal; A constant current control unit (501) for controlling the main switch (306) for controlling the constant current of the output current by performing duty control; A variable frequency control unit 502 for controlling the switch 307 for improving the power factor of the input terminal by performing variable frequency control; And the first winding (301), the second winding (302), and the third winding (303) of the coupling inductor are wound on one core.

The present invention can be applied to an LED power supply apparatus by a person skilled in the art by various modifications, and it should be recognized that the scope of the technology which easily transforms technically belongs to the scope of the present patent.

10: AC power source
20: input rectifier diode
21: Boost power factor improving circuit
22: Step-up type inductor
23: Main switch of the power factor improving circuit
24: first diode
25: second diode
26: Bank Capacitor
30: Main transformer
31, 32, 33: Converter
31: First converter
32: second converter
33: Third converter
34, 35, 36: rectifier diode
34: first rectifying diode
35: second rectifying diode
36: third rectifier diode
37, 38, 39: capacitors
37: first capacitor
38: second capacitor
39: third capacitor
41, 42, 43: LED group (Group)
41: First LED group (Group)
42: second LED group (Group)
43: Third LED group (Group)
51, 52, 53, 54: Current sensor
51: first current sensor
52: second current sensor
53: third current sensor
55: fourth current sensor
61, 62, 63: Buck converter
61: first step-down converter
62: Second Forcing Converter
63: Third Forced Converter
65, 66, 67: Switches of Buck converter
65: a first switch of the first step-down type converter
66: second switch of the second step-down converter
67: third switch of the third step-down converter
71, 72, 73: Diodes of buck converter
71: a first diode of the first step-down converter
72: second diode of the second step-down converter
73: third diode of the third step-down converter
74, 75, 76: Inductor of the buck converter
74: First inductor of the first step-down converter
75: second inductor of the second step-down converter
76: Third inductor of the third step-down converter
77, 78, 79: Output capacitors of a buck converter
77: a first output capacitor of the first step-
78: a second output capacitor of the second step-
79: a third output capacitor of the third step-
80, 81, 82: Buck converter controller
80: a first controller of the first step-down converter
81: Second controller of the second step-down converter
82: Third controller of the third step-down converter
301: first winding of coupling inductor
302: Secondary winding of coupling inductor
303: Third winding of coupling inductor
304: first divided capacitor
305: second divided capacitor
306: Main switch for constant current control
307: Switch for power factor improvement
308: Output diode
500: main controller
501: Constant current control unit
502: variable frequency control unit
510: Pulse Width Modulation (PWM) generator
511: Pulse Width Modulation Operational Amplifier (OP-AMP)
520: Constant current controller
521: Operational Amplifier for Constant Current Control (OP-AMP)
522: a first control gain determiner Z1;
523: the second control gain determiner Z2;
530:
531: Operational Amplifier for Current Control (OP-AMP)
532: Third control gain determining unit (Z3)
533: the fourth control gain determiner Z4;
534: third diode
541: Hysteresis operational amplifier (OP-AMP)
542: the fifth control gain determiner Z5;
543: sixth control gain determiner (Z6)
544: first resistance
545: N-type transistor
546: Second resistance
547: Third resistance
548; Oscillator (OSC)
549: first capacitor
550: RS flip-flop
551: Photo-Coupler
552: fourth resistance
553: Zener diodes
C1: first control capacitor
C2: second control capacitor
Icref: Input current reference value
Ioref: Output current reference value
R1: first control resistance
R2: second control resistance
Vc: Control voltage
Vcc1: first control power source
Vcc2: Second control power source
Vm: sawtooth voltage
Z1: the first control gain determiner
Z2: the second control gain determiner
Z3: the third control gain determiner
Z4: the fourth control gain determiner
Z5: fifth control gain determining section
Z6: sixth control gain decision unit

Claims (12)

In an LED power supply,
An input stage rectifier diode 20 for rectifying the AC power source 10;
A first winding (301) of a coupling inductor disposed at a positive output terminal of the input stage rectification diode (20);
A main switch 306 for constant current control connected to the other end of the first winding 301 of the coupling inductor;
First and second voltage dividing capacitors 304 and 305 connected to the other end of the first winding 301 of the coupling inductor and the drain terminal of the main switch 306 to divide the voltage;
A second winding (302) of a coupling inductor coupled to the contacts of the first and second voltage dividing capacitors (304, 305);
A switch 307 for improving power factor disposed between the other end of the second winding 302 of the coupling inductor and the negative power terminal;
An output diode 308 connected to the drain terminal of the switch 307 for improving the power factor and the other end of the second winding 302 of the coupling inductor;
A third winding 303 of a coupling inductor coupled to a cathode terminal of the output diode 308 and a source terminal of the main switch 306 for constant current control;
A plurality of LED groups (Groups 41, 42, 43) disposed between the other end of the third winding 303 of the coupling inductor and the negative power terminal;
A constant current control unit (501) for controlling the main switch (306) for controlling the constant current of the output current by performing duty control;
A variable frequency control unit 502 for controlling the switch 307 for improving the power factor of the input terminal by performing variable frequency control;
Wherein the first winding (301), the second winding (302), and the third winding (303) of the coupling inductor are wound on one core The method according to claim 1,
The constant current control unit 501 includes a current control unit 530, a constant current control unit 520 and a pulse width modulation (PWM) generation unit, and performs duty control. The method according to claim 1,
The variable frequency control unit 502 includes a hysteresis operational amplifier (OP-AMP) 541 for comparing the current information of the input stage rectifier diode 20 with the input current reference value Icref by the fourth current sensor 55 ≪ / RTI > The method of claim 3,
The variable frequency control unit 502 varies the resistance value of the RT terminal of the oscillator (OSC) 548 according to the output of the hysteresis operational amplifier (OP-AMP) The method according to claim 4,
The RS flip-flop 550 of the variable frequency controller 502 receives the control voltage Vc output from the constant current controller 520 and the output voltage of the oscillator 548 to generate a control signal having a variable frequency LED power supply < RTI ID = 0.0 > The method according to claim 1,
Wherein the constant current control operational amplifier (OP-AMP) 521 of the constant current control unit 501 is provided with first and second control gain decision units Z1 and Z2 522 and 523, The method according to claim 6,
The first control gain decision unit Z1 522 of the first and second control gain decision units Z1 and Z2 522 and 523 adopts the first control resistance R1 and the second control gain decision unit Z2 ) 523 is comprised of first and second control capacitors (C1, C2) and a second control resistor (R2) The method according to claim 1,
And the third and fourth control gain decision units (Z3, Z4) 532, 533 are arranged in the current control operational amplifier (OP-AMP) 531 of the constant current control unit 501. [ The method according to claim 1,
The hysteresis operational amplifier (OP-AMP) 541 of the variable frequency control unit 502 is provided with fifth and sixth control gain decision units Z5 and Z6 542 and 543, In an LED power supply,
An input stage rectifier diode 20 for rectifying the AC power source 10;
A first winding (301) of a coupling inductor disposed at a positive output terminal of the input stage rectification diode (20);
A main switch 306 for constant current control connected to the other end of the first winding 301 of the coupling inductor;
First and second voltage dividing capacitors 304 and 305 connected to the other end of the first winding 301 of the coupling inductor and the drain terminal of the main switch 306 to divide the voltage;
A second winding (302) of a coupling inductor coupled to the contacts of the first and second voltage dividing capacitors (304, 305);
A switch 307 for improving power factor disposed between the other end of the second winding 302 of the coupling inductor and the negative power terminal;
An output diode 308 connected to the drain terminal of the switch 307 for improving the power factor and the other end of the second winding 302 of the coupling inductor;
A third winding 303 of a coupling inductor coupled to a cathode terminal of the output diode 308 and a source terminal of the main switch 306 for constant current control;
A plurality of LED groups (Groups 41, 42, 43) disposed between the other end of the third winding 303 of the coupling inductor and the negative power terminal;
A constant current control unit 501 for controlling the main switch 306 for the constant current control by performing duty control of the current control unit 530 and the constant current control unit 520. The constant current control unit 501 includes a current control unit 530, (PWM: Pulse Width Modulation) generator;
A variable frequency control unit 502 for controlling the switch 307 for improving the power factor by performing variable frequency control; the variable frequency control unit 502 includes an RS flip flop 550, an oscillator (OSC) 548, and a hysteresis An operational amplifier (OP-AMP) 541;
Wherein the first winding (301), the second winding (302), and the third winding (303) of the coupling inductor are wound on one core 11. The method of claim 10,
The RS flip-flop 550 of the variable frequency controller 502 receives the control voltage Vc output from the constant current controller 520 and the output voltage of the oscillator 548 to generate a control signal having a variable frequency And controls the switch (307) for improving the power factor, 11. The method of claim 10,
The first and second control gain decision units Z1 and Z2 522 and 523 are disposed in the constant current control operational amplifier OP-AMP 521 of the constant current control unit 501. The first and second control gain decision units The first control gain decision section Z2 522 adopts the first control gain decision section Z2 523 as the first control resistance R1 and the second control gain decision section Z2 523 as the first control gain decision section Z2, Capacitors (C1, C2) and a second control resistor (R2).

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