KR101047027B1 - Constant Current Driving Unidirectional LED Module Device - Google Patents

Abstract

The present invention provides a constant current driving unidirectional LED module device that can suppress the flicker phenomenon due to the AC LED operating characteristics according to the application of the AC power, can reduce the light efficiency, and can improve the power factor.

The constant current drive unidirectional LED module device of the present invention, the rectifier for receiving rectified AC power; A unidirectional LED module unit connected to one end of the rectifying unit; And a constant current unit connected between the unidirectional LED module unit and the other end of the rectifying unit to provide a constant current.

LED, AC, Constant Current, Unidirectional, Power Factor

Description

Constant Current Driven Unidirectional LED Module Unit {UNIDIRECTIONAL LIGHTING EMITTING DIODE MODULE DEVICE TO DRIVE WITH CONSTANT CURRENT}

The present invention relates to a constant current drive unidirectional LED module device, and more particularly, to a unidirectional LED module device driven with a constant current.

LED (Luminescent Diode) can operate when a constant current is supplied to the current driving device. In particular, LEDs that require high power generate a lot of heat in the LEDs themselves because of their large driving current (typically 350mA or more), which results in a higher degradation rate of luminance than LEDs at low power. This is directly linked to the lifetime of the LED and is very important in the lighting market. Accordingly, all LEDs at high power are driven with a constant current, and are driven in a pulse width modulation (PWM) scheme to more efficiently use the power of the SMPS used as the constant current power source.

However, this method requires an electronic component, which increases the manufacturing cost. Therefore, recently, a method of rectifying AC power and applying the same to an LED module connected in series has been applied.

1 is a unidirectional LED module device according to the prior art.

The unidirectional LED module device according to the prior art includes a bridge diode 120 for rectifying the applied AC power source 110, and a unidirectional LED module 130 coupled to the bridge diode 120 through a resistor (R1). .

Here, the resistor R1 determines the magnitude of the current flowing in the unidirectional LED module 130.

2 is a waveform diagram of applied voltage and driving current in a unidirectional LED module according to the related art, where v is a voltage waveform to be applied and i is a current waveform flowing to the front of the bridge diode 120 according to the applied AC voltage.

When the positive half-cycle voltage of the AC power source 110 is applied, current flows and the LED module 130 emits light when the magnitude of the voltage is greater than or equal to the forward threshold voltage of the LED module 130. Similarly, in the negative half-cycle of the AC power supply 110, the current flows and the LED module 130 emits light when the magnitude of the voltage is equal to or greater than the forward threshold voltage of the LED module 130. That is, as shown in Figure 2, the load current does not flow in the section a and b.

As described above, when the magnitude of the applied voltage is greater than or equal to the forward threshold voltage, the conduction is performed when the operating characteristic of the LED module 130 that is operated only, that is, is greater than or equal to the forward threshold voltage of the LED module 130 connected forward by the application of AC power. The power factor is low and total harmonic distortion (THD) is caused by the sudden flow of current and the short operating range of the LED module within one cycle of the applied AC power. There is a problem that increases, and excessive flicker occurs. In addition, there is also a problem that the light efficiency is lowered due to this.

The present invention has been made to solve the above problems is an object of the present invention to provide a constant current drive unidirectional LED module device that can suppress the flicker phenomenon due to the AC LED operating characteristics according to the application of the AC power.

In addition, another object of the present invention is to provide a constant current driving unidirectional LED module device that can improve the light efficiency degradation due to the AC LED operating characteristics according to the application of the AC power.

In addition, another object of the present invention is to provide a constant current driving unidirectional LED module device that can improve the power factor decrease due to the AC LED operating characteristics according to the application of the AC power.

The constant current drive unidirectional LED module device of the present invention, the rectifier for receiving rectified AC power; A unidirectional LED module unit connected to one end of the rectifying unit; And a constant current unit connected between the unidirectional LED module unit and the other end of the rectifying unit to provide a constant current.

Preferably, the constant current unit, the switching unit is connected between the LED module unit and the other end of the rectifying unit for switching using the pulse flow outputted by the rectifier; A control voltage output unit detecting a load current flowing in the unidirectional LED module unit and converting a switching voltage output from the switching unit into driving voltages of first and second levels according to the detected load current; And a constant current driver configured to control the driving voltages of the first and second levels to provide a constant current.

Preferably, the constant current unit detects a load current flowing through the unidirectional LED module unit, and determines a voltage between the LED module unit and the other end of the rectifying unit according to the magnitude of the detected load current to drive voltages of the first and second levels. Control voltage output unit for converting to; And a constant current driver configured to control the driving voltages of the first and second levels to provide a constant current.

Preferably, the battery module may further include a charge / discharge unit including a resistor-capacitor connected in parallel with the upper diode and / or the lower diode of the rectifier.

Preferably, the constant current driver may be any one of a field effect transistor (FET), a bipolar junction transistor (BJT), and an insulated gate bipolar transistor (IGBT).

Preferably, the control voltage output unit, the detection resistor for detecting a load current flowing through the unidirectional LED module; And a driving voltage of a first level of a zener voltage when the control voltage applied to the detection resistor is less than or equal to a set value, and driving of a second level that maintains a short circuit state between an anode and a cathode when the control voltage exceeds the set value. It may include a three-terminal zener diode for outputting a voltage.

Preferably, when the applied voltage of the AC power source fluctuates in the range of 10% of the rated voltage, the load current flowing in the unidirectional LED module unit varies in the range of 5 to 20%.

Preferably, when the applied voltage of the AC power source fluctuates in the range of 10%, the light quantity of the unidirectional LED module unit varies in the range of 5 to 20%.

According to the present invention, it is possible to suppress the flicker phenomenon caused by the AC LED operating characteristics according to the application of the AC power supply is suitable for use as an illumination device. Since the flicker phenomenon is suppressed, there is an effect of extending the life of the lighting device. Further, according to the present invention, it is possible to improve the light efficiency drop and to improve the power factor drop.

In addition, compared with the prior art, the LED operating period is wider, and thus, the effective power is increased to improve the power factor (PF), and the effective value of the fundamental wave is larger, so that the total harmonic distortion (THD) is improved.

Hereinafter, exemplary embodiment (s) of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the elements of each drawing, it should be noted that the same elements are denoted by the same reference numerals as much as possible even if they are displayed on different drawings. In addition, many specific details are shown in the following description, which is provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. Will be self-evident. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

3 is a circuit diagram of a constant current driving unidirectional LED module device according to a first embodiment of the present invention.

A unidirectional LED module device driven by a constant current according to an embodiment of the present invention, the rectifier 320 for receiving the rectified commercial AC power source 310; One-way LED module 330 connected to one end of the rectifier 320; It includes a constant current unit 340 is connected between the other end of the LED module 330 and the rectifier 320 to provide a constant current.

The constant current unit 340 according to the exemplary embodiment of the present invention is connected between the LED module unit 330 and the other end of the rectifying unit 320 and the switching unit 341 for switching using the pulse flow output from the rectifying unit 320 The control voltage output detects a load current flowing through the unidirectional LED module 330 and converts the switching voltage output from the switching unit 341 into driving voltages of the first and second levels according to the detected load current. The unit 342 includes a constant current driver 343 controlled to drive voltages of the first and second levels to provide a constant current.

The switching unit 341 is turned on at the Zener voltages of the first resistor R1 and the first Zener diode ZD1 and the first Zener diode ZD1 connected in series between the LED module unit 330 and the other end of the rectifier 320. The second FET Q2 is turned off, and a second resistor R2 having one end coupled to the source terminal of the second FET Q2.

The control voltage output unit 342 is provided between the detection resistor Rsen coupled between the source terminal of the first FET Q1 and the other end of the rectifier 320, and the other end of the second resistor R2 and the other end of the rectifier 320. And a three-terminal zener diode 3ZD coupled to and controlled by a control voltage Vcon applied to the detection resistor to output driving voltages of first and second levels.

The constant current driver 343 includes a first FET Q1 coupled between the unidirectional LED module 330 and the detection resistor Rsen to vary an operation region according to driving voltages of the first and second levels.

Referring to the operation of the constant current driving unidirectional LED module device according to an embodiment of the present invention.

When the voltage applied between the LED module 330 and the other end of the rectifier 320 exceeds a predetermined level, both ends of the zener diode ZD1 maintain the zener voltage, and the second FET Q2 is turned on at the zener voltage.

The three-terminal zener diode (3p-ZD) has the same characteristics as the general zener diode characteristic when the control voltage (Vcon) applied to the detection resistance is lower than the set value, and outputs the zener voltage, and the anode when the control voltage (Vcon) exceeds the set value. Maintain a short between the and cathode.

The first FET Q1 operates in the saturation region according to the first driving voltage applied from the three-terminal zener diodes 3p-ZD, that is, the zener voltage, when the control voltage is less than or equal to the set value. On the other hand, when the control voltage exceeds the set value, since the three-terminal zener diodes 3p-ZD operate in a short-circuit state, the control voltage applied to the detection resistor Rsen is reversed to the gate-source terminal of the first FET Q1. The first FET Q1 is applied in the state to operate in the active region, so that the load current has a constant current characteristic.

FIG. 4 is a circuit diagram of a unidirectional LED module device driven with a constant current according to a second embodiment of the present invention, and most configurations are the same as those of the first embodiment of FIG.

However, the operation of the constant current unit 440 is identical except that the switching unit 441 is configured to provide a constant current using two FETs instead of the switching unit 341 in the first embodiment of FIG. 3.

FIG. 5 is a circuit diagram of a unidirectional LED module device driven with a constant current according to a third embodiment of the present invention, and most configurations are the same as those of the first embodiment of FIG.

However, the operation of the constant current unit 540 is the same except that the switching unit 341 in the first embodiment of FIG. 3 is removed.

FIG. 6 is a circuit diagram of a unidirectional LED module device driven with a constant current according to a fourth embodiment of the present invention, and further includes a charge / discharge unit 350 in the circuit of the first embodiment of FIG.

The charging and discharging unit 350 includes a resistor R3-capacitor C1 and a resistor R4-capacitor C2 coupled in parallel to the upper diode D3 and the lower diode D4 of the rectifier 320. The capacitor C1 and the capacitor C2 discharge the energy to the LED module unit by complementarily charging the energy of the AC power. That is, the resistor R3-capacitor C1 stores the AC voltage during the positive half cycle of the AC power supply and discharges the stored energy during the negative half cycle. Resistor R4-capacitor C2 stores the AC voltage during the negative half cycle of the AC power supply and discharges the stored energy during the positive half cycle.

Meanwhile, the charge / discharge unit 350 according to an embodiment of the present invention may be similarly applied to the second embodiment of FIG. 4 or the third embodiment of FIG. 5.

FIG. 7 is a voltage and current waveform diagram of a unidirectional LED module device driven with a constant current according to a fourth embodiment of the present invention. According to the present invention, the LED operating section is wider than the conventional circuit of FIG. Increased power improves power factor (PF), and the fundamental harmonic value is larger, which improves total harmonic distortion (THD).

8 is a light output waveform diagram according to the prior art compared to the light output according to the first to third embodiments of the present invention.

According to the present invention, it can be seen that there is no change in the light output since the change in the current peak can be minimized by limiting the increase in the AC peak storage even if the input power supply voltage changes.

In contrast, according to the related art of FIG. 1, since the current varies in proportion to the change in the AC power supply voltage, the light output also changes.

On the other hand, Figure 8 ignores the effect of the charging and discharging unit according to an embodiment of the present invention.

9 is a graph of current characteristics compared to applied voltages of the prior art and the present invention. In the present invention, the variation of the load current shows a very small constant current characteristic even if the applied voltage changes.

That is, according to the prior art, when the applied voltage is reduced by 10% compared to the rated voltage and 200 volts is applied, the load current is reduced (40.04-29.87) / 40.04 * 100 = 25.4%, the applied voltage is 10 compared to the rated voltage When 240 volts is applied by% increase, the load current increases by (50.71-40.04) /40.04*100 = 26.6%.

On the other hand, according to an embodiment of the present invention, the load current is reduced (39.71-36.95) / 39.71 * 100 = 7% when applying 200 volts, the load current is increased by (41.83-39.71) / 39.71 = 5.3% when applying 240 volts do. Here, the circuit of the prior art and the circuit of the present invention are implemented for an 8-watt LED lamp.

FIG. 10 is a graph of light quantity characteristics versus applied voltages of the prior art and the present invention, and it can be seen that the increase in the amount of light is not significant even if the applied voltage is increased in the present invention compared to the prior art.

That is, according to the prior art, when the applied voltage is reduced by 10% compared to the rated voltage and 200 volts is applied, the amount of light is reduced (401-300) / 401 * 100 = 25.2%, the applied voltage is 10% compared to the rated voltage When 240 volts is applied to increase, the amount of light increases (502-401) / 401 * 100 = 25.2%.

On the other hand, according to the embodiment of the present invention, the amount of light is reduced (430-386) / 430 * 100 = 10.2% when applied at 200 volts, and the amount of light is increased (464-430) / 430 = 7.9% when applied at 240 volts. Here, the circuit of the prior art and the circuit of the present invention are implemented for an 8-watt LED lamp.

As described above, although the specific embodiment (s) have been described in the detailed description of the present invention, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiment (s), but should be defined by the appended claims and equivalents thereof.

1 is a unidirectional LED module device according to the prior art,

Figure 2 is a waveform diagram of the applied voltage and driving current in the unidirectional LED module according to the prior art,

3 is a circuit diagram of a constant current driving unidirectional LED module device according to a first embodiment of the present invention;

4 is a circuit diagram of a unidirectional LED module device driven with a constant current according to a second embodiment of the present invention;

5 is a circuit diagram of a unidirectional LED module device driven with a constant current according to a third embodiment of the present invention;

6 is a unidirectional LED module device circuit diagram driven by a constant current according to a fourth embodiment of the present invention;

7 is a voltage and current waveform diagram of a unidirectional LED module device driven with a constant current according to a fourth embodiment of the present invention,

8 is a light output waveform diagram according to the prior art compared to the light output according to the first to third embodiments of the present invention,

9 is a graph of current characteristics versus current applied voltage of the prior art and the present invention, and

Figure 10 is a graph of the light quantity characteristics compared to the applied voltage of the prior art and the present invention.

DESCRIPTION OF THE RELATED ART [0002]

310: commercial AC power source 320: rectifier

330: unidirectional LED module portion 340: constant current portion

341: switching unit 342: control voltage output unit

343: constant current drive unit 350: charge and discharge unit

Claims (8)

Rectifying unit for receiving rectified AC power; A unidirectional LED module unit connected to one end of the rectifying unit; And A constant current unit connected between the one-way LED module unit and the other end of the rectifying unit to provide a constant current, The constant current unit, A switching unit connected between the LED module unit and the other end of the rectifying unit and switched using a pulse current output by the rectifying unit; A control voltage output unit for detecting a load current flowing in the unidirectional LED module unit and converting a switching voltage output from the switching unit into a driving voltage of a first or second level according to the detected load current; And A constant current driver which is controlled by the driving voltage of the first or second level to provide a constant current Constant current drive unidirectional LED module device comprising a. delete Rectifying unit for receiving rectified AC power; A unidirectional LED module unit connected to one end of the rectifying unit; And A constant current unit connected between the one-way LED module unit and the other end of the rectifying unit to provide a constant current, The constant current unit, A control voltage output unit for detecting a load current flowing through the unidirectional LED module unit and converting a voltage between the LED module unit and the other end of the rectifying unit into driving voltages of first and second levels according to the detected load current; And A constant current driver which is controlled by the driving voltages of the first and second levels to provide a constant current Constant current drive unidirectional LED module device comprising a. The method according to claim 1 or 3, And a charging and discharging unit including a resistor-capacitor connected in parallel with the upper diode and / or the lower diode of the rectifying unit. 5. The method of claim 4, And the constant current driver is any one of a field effect transistor (FET), a bipolar junction transistor (BJT), and an insulated gate bipolar transistor (IGBT). The method of claim 4, wherein the control voltage output unit, A detection resistor for detecting a load current flowing through the unidirectional LED module; And When the control voltage applied to the detection resistor is less than or equal to a set value, a zener voltage, which is a driving voltage of the first level, is output; 3-terminal zener diodes that output voltage Constant current drive unidirectional LED module device comprising a. 5. The method of claim 4, The constant current driving unidirectional LED module device, characterized in that the load current flowing in the unidirectional LED module portion varies in the range of 5 to 20% when the applied voltage of the AC power is changed in the range of 10% of the rated voltage. 5. The method of claim 4, When the voltage applied to the AC power supply fluctuates in the range of 10%, the light quantity of the unidirectional LED module unit varies in the range of 5 to 20%.

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