KR101061417B1 - LED driving circuit by pulse width modulation control method - Google Patents

Abstract

An LED driving circuit using a PWM for driving a plurality of LEDs is disclosed, which includes: a ballast (12) for receiving a regulated AC 220V and supplying regulated power; A power factor correction circuit (PFC) 13 for operating in the same form as the phase of the voltage and current of the output voltage of the ballast to compensate the power factor from 0.95 to 0.98; The terminal Vin inputs the voltage from the power factor correction circuit 13, the ground terminal GND connected to ground, the ADJ terminal ADJ to which the PWM signal is input, and the current value applied to the LED lamp. An output driver 18 including a driver IC ₁₀ having an isense terminal for sensing a signal and a terminal Lx connected to drive the LED lamp; A constant voltage controller 16 for applying a constant voltage to the terminal Vin of the driver IC ₁₀ ; A constant current controller 17 for applying a constant current to a terminal Isense of the driver IC ₁₀ ; And a PWM signal generator for providing a PWM signal applied to the ADJ terminal of the driver IC ₁₀ .

LED, ballast, LED lamp, PWM control constant voltage and constant current drive

Description

LED driving circuit by pulse width modulation control method {Driving circuit for a light emitting diode by pulse width modulation control}

The present invention relates to a driving circuit of a high-efficiency LED lamp, and more particularly, using an LED having a high illuminance and a low heat generation and a low power consumption as a light source, and an LED sensitive to temperature and current is exposed to a high temperature and an overcurrent is introduced. Therefore, the present invention relates to an LED driving circuit using a PWM control method to increase heat dissipation and efficiently control an inflow current so that the life of the LED is not shortened.

Widely used by consumers as a light source to illuminate the dark place has been progressed from incandescent lamps to fluorescent lamps, and three-wavelength bulbs, and recently, LEDs that consume less power and have a longer lifespan than incandescent lamps, fluorescent lamps, and three-wavelength bulbs as light sources. The lighting to use is developed and released.

As described above, as for a lamp using a LED as a light source, a number of publications have been disclosed, such as Utility Model No. 430022, 'High Brightness LED Lamp', and Patent No. 707874, 'Installation Structure of Light-Emitting Diode Street Light.'

The configuration of the lamp of the registered patent and the utility model is a circuit board on which the LED is mounted, a heat sink of an aluminum material to which the circuit board is attached, a cover covering the surface of the LED, and a socket connected to the circuit board. And a connection terminal for supplying power, and a power supply for converting AC power into direct current and outputting the same to the outlet.

Such a configuration is generally adopted in a lamp using an LED. The challenge is to ensure that LEDs that are sensitive to temperature and current are not exposed to high temperatures or overcurrent flow, which shortens their lifetime. To this end, a means for further improving heat dissipation efficiency and a means for appropriately adjusting the strength of the current supplied to the circuit board are required.

Just like the lighting of the registered patent and the utility model, simply attaching a circuit board to a heat sink made of aluminum does not provide sufficient heat dissipation effect. The reason is that the circuit board is usually made of synthetic resin material for cost reduction, and the circuit pattern, which is a conductor for supplying power to the LED, is formed on one surface of the circuit board, which is the mounting surface of the LED, and the heat transfer rate of the synthetic resin material is low. . Therefore, there is a need for a means that can dissipate heat generated from circuit boards (LEDs and circuit patterns) and efficiently transfer them to heat sinks.

Meanwhile, the present applicant has devised a lighting lamp for a high efficiency lamp as shown in FIGS. 1 and 2, which includes a base 2 having an LED assembly using a plurality of LEDs 1 as a light emitting device. In order to dissipate high heat generated on the back surface of the LED assembly when the LEDs 1 emit light on the upper surface of the (2), the surface of the base (2) is provided with a heat dissipation means (notation notation), the base (2) is provided with a driving circuit for driving the LEDs (1).

Various types of LED driving circuits are used. For example, there is a method of controlling voltage and current in a linear manner. In the linear voltage method, a constant current flows by connecting a LED and a resistor to a constant voltage output from a constant voltage IC. The linear constant current method uses a constant current IC to output a constant current. This linear method has the disadvantage that the circuit is simple but the efficiency is not good and heat is generated.

3 illustrates an example of an LED driving circuit using a conventional switch mode power supply (SMPS) method, which is a voltage regulator IC ₁ , a low power voltage comparator IC ₂ , and resistors R ₁ to R ₈ . , The capacitor C ₁ , and the backflow prevention diode D ₁ were used to drive the plurality of LEDs LED ₁ to LEDn.

However, the SMPS driving circuit shown in FIG. 3 drives the LED with a more economical configuration in driving the LED, since the number of modules that can be driven per capacity is small, and it is efficient to reduce heat generation and ensure stability of life. And economical LED driving circuit is urgently needed.

In other words, the conventional method has a problem such as unnecessary power consumption due to low power efficiency, intermittent failure due to internal breakdown voltage and insulation resistance, temperature rise due to overcurrent generation, and the conventional control apparatus. It also has a problem that various voltages and currents occur irregularly.

The present invention can improve the power efficiency by blocking the temperature rise due to unnecessary power consumption or overcurrent of the power supply including the ballast, in particular, LED lamp by repeatedly turning on / off for one second dozens of times It is to provide LED driving circuit by PWM control method to extend efficiency and lifespan by reducing the stress to automatic pulse width modulation control.

The present invention for achieving the above object and the ballast for supplying a regulated power input to AC AC220V; A power factor correction circuit (PFC) for operating in the same manner as the phase of the voltage and current of the output voltage of the ballast to compensate the power factor from 0.95 to 0.98; Detecting terminal (Vin) to which 7V ~ 30V input voltage is supplied, ground terminal (GND) connected to ground, ADJ terminal (ADJ) to input PWM signal, and current value applied to LED lamp An output driver including an driver IC ₁₀ having an isense terminal and a terminal Lx connected to drive the LED lamp; A constant voltage control unit for applying a constant voltage to the terminal Vin of the driver IC ₁₀ ; A constant current controller for applying a constant current to a terminal Isense of the driver IC ₁₀ ; And a PWM signal generator for providing a PWM signal applied to the ADJ terminal of the driver IC ₁₀ .

The present invention can improve the power efficiency of the inverter and the like by extending the lifespan due to unnecessary power consumption or overcurrent of the power supply device by using the pulse width modulation method, which is not the SMPS method, and has an effect of extending the lifespan. .

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

Figure 4 is a block diagram of the LED driving circuit according to the PWM control method used in the present invention, which is a constant voltage and constant current control to the lamp in a lighting device such as a traffic light or street lamp and lamp having one or more LEDs It is to enable the function.

As can be seen in FIG. 4, the input power supply unit 11 has an input terminal to which only commercial power having a constant voltage of one of commercial power, such as 110V or 220V, is input, and the input power is supplied to a ballast 12 that is a ballast. The voltage and current are applied to the power factor correction circuit (PFC) 13, and the power factor correction circuit (PFC) 13 is equal to the phase of the voltage and current of the output voltage of the ballast. It operates in the form of power factor to compensate for power factor of 0.95 ~ 0.98 so that stable power is supplied. The power having the power factor correction is supplied to the output power supply unit 14, and the output power supply unit 14 is applied to the input power supply unit 16 via the connector 15, which is a connection unit, via a DC power supply line.

The signal applied to the input power supply unit (Vin) 16 is automatically set by the constant voltage control unit 17 and the constant current control unit 18 to satisfy the control condition for driving the LED lamp, and then returns to the output power supply unit 19. It is converted to drive the LED lamp (20).

Here, the output of the output driver 19 is arbitrarily set to drive the LED lamp 20 constituting various lighting devices such as a lamp, a street lamp, a traffic light, etc. in response to the output of the constant voltage controller 17 and the constant current controller 18. Adjust the output of the LED lamp 20 to maintain one level.

The constant voltage controller 17 and the constant current controller 18 are supplied to the LED lamp 20 through the output driver 19.

The constant voltage and constant current protection circuits 17 and 18 are provided at the rear end of the LED driver 20 so that the power supplied to the LED lamp can maintain the constant voltage and the constant current. Therefore, the lifetime of the LED lamp 20 constituting various lighting devices can be extended from overvoltage or overcurrent.

5 shows a detailed circuit diagram of the constant voltage controller 17, the constant current controller 18, and the output driver 19 used in the present invention. The constant voltage controller 17 includes a capacitor C ₁₁ , C ₁₂ and a resistor. It is composed of (R ₁₁ , R ₁₂ ) to apply a constant voltage (for example 7V ~ 30V) to the input terminal (Vin) of the driver (IC ₁₀ ).

The ADJ terminal of the driver IC ₁₀ is configured to input a pulse width modulated signal consisting of resistors R ₁₃ and R ₁₄ , a transistor Q ₁₀ , and a capacitor C _13. Here, the ADJ terminal of the driver IC ₁₀ is input. The terminal controls the on / off and brightness of the LED lamp 20.

The LX terminal of the driver IC ₁₀ is connected to a constant current control unit including a capacitor C ₁₄ , a coil L ₁₁ , and a diode D ₁₁ .

The driver IC ₁₀ used in the present invention is preferably designed to operate at an input voltage of about 7V to 30V and provide about 1ADML output current. The driver IC ₁₀ can incorporate an output switch and an output current sensing circuit, which can be used to set a normal average output current using an external resistor. In addition, the output current exceeds the set value by applying an external control signal to the ADJ terminal of the driver IC ₁₀ , that is, a PWM signal generated by the resistors R ₁₃ and R ₁₄ and the transistors Q ₁₀ and the capacitor C ₁₃ . It can be adjusted below. In other words, it can be properly adjusted according to the number of LED lamps 18.

In addition, the PWM signal generator is preferably connected to the temperature sensing circuit by a circuit element such as a thermistor to solve the heat problem by the LED lamp 20.

6 is a signal waveform of each part of the driver IC ₁₀ illustrated in FIG. 5, and as shown in FIG. 6, the ADJ terminal is applied to the PWM waveform, which provides an appropriate output current according to the control frequency. The PWM signal provides a soft-start time by controlling the rise time of the input / output current. This soft-start point uses a capacitor from the ADJ terminal to ground (GND). May increase.

On the other hand, the driver IC ₁₀ may add a function for detecting a bad state of the LED or a switching function for turning on / off various lighting devices including the LED. Further, by adding a remote control function to the driver or by adding an internet communication function, it is possible to remotely control various operations of various lighting devices having LEDs.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, but many variations and modifications may be made in the following claims.

The present invention can be applied to low-voltage halogen replacement LEDs, automotive headlamps, low-voltage industrial lighting, LED backup lights, signs, and the like.

1 is a side view of the exterior of a lamp having an LED;

2 is a cross-sectional view taken along the line II-II in FIG. 1;

3 is a conventional LED driving circuit diagram;

4 is a block diagram of an LED driving circuit according to the PWM control method according to the present invention;

5 is a detailed circuit diagram of the main part of the present invention shown in FIG. And

6 is a waveform diagram of each part of the output driver shown in FIG. 5.

※ Explanation of code about main part of drawing ※

11: input power supply unit 12: ballast

13: power factor correction circuit 14: output power supply

15: output connection 16: input power supply

17: constant voltage control unit 18: constant current control unit

19: driver 19: LED lamp

Claims (4)

In LED driving circuit using PWM to drive multiple LEDs: A ballast 12 for receiving AC AC 220V and supplying regulated power; A power factor correction circuit (PFC) 13 for operating in the same form as the phase of the voltage and current of the output voltage of the ballast to compensate the power factor from 0.95 to 0.98; The terminal Vin to which the voltage is applied from the power factor correction circuit 13, the ground terminal GND connected to the ground, the ADJ terminal ADJ to which the PWM signal is input, and the current value applied to the LED lamp An output driver 19 including a driver IC ₁₀ having an isense terminal for sensing a signal and a terminal Lx connected to drive the LED lamp; A constant voltage controller 17 for applying a constant voltage to the terminal Vin of the driver IC ₁₀ ; A constant current controller 18 for applying a constant current to a terminal Isense of the driver IC ₁₀ ; And LED driving circuit according to the PWM control method characterized in that it comprises a PWM signal generator for providing a PWM signal applied to the ADJ terminal of the driver (IC ₁₀ ). The method of claim 1, wherein the PWM signal generation unit, Including a resistor (R ₁₃ , R ₁₄ ), a transistor (Q ₁₀ ) and a capacitor (C ₁₄ ) for generating a gated signal (gated-signal) by receiving the power generated from the constant voltage control unit 17 LED driving circuit by PWM control method. The method of claim 1, wherein the constant voltage control unit 17, An LED driving circuit according to the PWM control method comprising a capacitor (C ₁₁ , C ₁₂ ) and a resistor (R ₁₁ , R ₁₂ ) to supply an input voltage of 7V ~ 30V. The method of claim 1, wherein the constant current control unit 18, LED driving circuit according to the PWM control method characterized in that it comprises a diode (D11), a capacitor (C14), and a coil (L11) for feeding back over current when the LED lamp flows.

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