KR20130055285A - Driving apparatus for lighting device - Google Patents

Abstract

PURPOSE: A light emitting drive device is provided to relieve a limit cycle phenomenon while precisely controlling a LED current without a resolution control of an ADC or a pulse width modulation module. CONSTITUTION: A driver(120) switches an input power and supplies a drive power to a light emitting device. A drive controller(110) controls the power switching of the driver by mixing multiple preset switching patterns according to a voltage difference between the voltage level of the drive power and a preset reference voltage. The drive controller includes an ADC(111), a controller(112), a duty setting unit(113), and a switching controller(114). The ADC receives a feedback of drive power and converts into a digital signal. The controller compares the voltage level of the digital signal with the reference voltage and controls a duty setting according to the result of the comparison. The duty setting unit sets up a switching duty by mixing at least two switching patterns which have a switching duty which is set in advance according to the control of the controller in a switching signal group unit. The switching controller controls the power switching duty of the driver according to the control signal of the duty setting unit. [Reference numerals] (112) Controller; (113) Duty setting unit; (114) Switching controller; (130) Light emitting device

Description

Light-emitting element driving device {DRIVING APPARATUS FOR LIGHTING DEVICE}

The present invention relates to a light emitting device driving device that eliminates the limit cycle phenomenon.

In general, light emitting devices are used in devices that require light, such as indoor lighting, street lamps, and televisions.

Recently, light emitting diodes, particularly high output light emitting diodes, have been attracting attention. High power light emitting diodes (LEDs) are the next generation of lighting devices due to their long lifespan, low maintenance cost, and high efficiency. Moreover, it is free from pollutants and harmful gases, and is a light source that does not use mercury.

As a result, the value of LEDs is growing even further in Europe and around the world, in preparation for, or already starting to reduce production and regulation of incandescent and fluorescent lamps. The incidence of incandescent light bulbs, such as the European Union (EU) to end incandescent light bulbs by 2012, has become the biggest issue of energy efficiency in lighting equipment in the international community.

Instead of disappearing incandescent bulbs, the spread of high-efficiency light emitting diodes (LEDs) is expanding. In Korea, the gradual replacement of LED lighting with a focus on public institutions has been in full swing since 2009, and street lamps will be replaced with LED lamps starting from 2009. In addition, the company is planning to prohibit the sale of incandescent lamps from 2013 and replace it with LED lamps. Therefore, the LED industry is expected to enter the full-scale growth cycle starting from 2009.

However, in the high-end lighting market, for example, nightclubs and exhibitions, existing lighting is rapidly recognized because it is free to express the performance, that is, the dynamic color or aesthetic sense that can catch the eye, rather than the price of LED. It is expected to be replaced. In addition, as the well-being craze that pursues quality of life and happiness spreads rapidly around us, interest in light closely related to life is increasing, and cutting-edge lighting technology is being researched and developed.

The LED has a very high color reproducibility and fine adjustment of color temperature and brightness, which makes it suitable for such emotional lighting. Thus, the characteristics of LED as an illumination (light source) are summarized as follows.

-As a light source with low heat loss, power consumption is very small compared to incandescent bulb, which saves energy and shows excellent characteristics in terms of life and maintenance.

-Illumination light source using LED is a combination of LED, which can realize a rich color light source.

-Excellent mechanical strength, low power consumption.

-Since the weight is light due to the integrated type (power supply part, lamp part, base part), transportation cost can be reduced.

 High-power LEDs, unlike conventional small LEDs, require a driver circuit with stable operation and efficiency because the power rate exceeds 1W. In addition, in the case of lighting products, power consumption of tens to hundreds of W is used, so a driving method using a resistor is not suitable for a high efficiency LED lighting system.

In general, driver control circuits have mainly used analog control circuits, and have externally implemented dimming digitally to construct LED lighting systems. Recently, a method of digitally controlling the internal structure of the LED driving circuit with the improvement of the microcontroller unit function has been introduced.

This method eliminates the external analog control chip, which has the advantage of being advantageous for Asic. In particular, the digital method has its advantages as the number of LED modules increases.

This digital method uses an analog-to-digital converter (ADC) and a pulse width modulation (PWM) module.

Due to the difference in resolution between the analog-to-digital converter and the pulse width modulation module, there is a limit cycle in which the digital signal used to drive the LED fluctuates by 1 to 2 bits, and thus the voltage supplied to the LED. There is a problem that the LED flickers because of ripple.

In order to solve this problem, the resolution of the pulse width modulation module can be improved, but this has the problem of increasing the manufacturing cost of the driving device, and conversely, lowering the resolution of the analog-to-digital converter has a problem that precise LED current control is difficult. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and the present invention is to mix a plurality of switching patterns each having a preset duty according to the difference between the voltage supplied to the light emitting diode and the reference voltage, analog-to-digital converter or pulse It provides LED driving devices that can eliminate limit cycles while precisely controlling LED current without adjusting the width modulation module's resolution.

In order to solve the above problems of the present invention, one technical aspect of the present invention is a driving unit for supplying the driving power to the light emitting device by switching the input power; And

According to an aspect of the present invention, there is provided a light emitting device driving apparatus including a driving control unit for controlling power switching of the driving unit by mixing a plurality of preset switching patterns according to a voltage difference between a voltage level of the driving power source and a preset reference voltage.

According to one technical aspect of the invention, the drive control unit

An ADC receiving the feedback of the driving power and converting the driving power into a digital signal;

A controller which compares the voltage level of the digital signal from the ADC with the reference voltage and controls the duty setting according to the comparison result;

A duty setting unit for setting a switching duty by mixing at least two switching patterns having a preset switching duty in units of a preset switching signal group under the control of the controller; And

And a switching controller for controlling the power switching duty of the driving unit according to the control signal of the duty setting unit.

According to one technical aspect of the present invention, the duty setting unit may include a first switching pattern having a first switching duty preset and a second switching duty different from the first switching duty of the first switching pattern. Two switching patterns can be mixed.

According to one technical aspect of the present invention, the duty setting unit may mix the first switching pattern and the second switching pattern at least once, and the duty setting unit may include the first switching pattern and the second switching pattern. Can be mixed alternately.

According to one technical aspect of the present invention,

A switching unit for switching the input power according to the switching control of the driving control unit; And

It may include an output filter unit for filtering the power switched by the switching unit.

According to the present invention, the LED current is precisely adjusted without adjusting the resolution of the analog-to-digital converter or the pulse width modulation module by mixing a plurality of switching patterns each having a preset duty according to the difference between the voltage supplied to the light emitting diode and the reference voltage. While controlling, there is an effect that can eliminate the limit cycle phenomenon.

1 is a schematic configuration diagram of a light emitting element driving apparatus of the present invention.
2 and 3 show an embodiment of switching pattern mixing of the light emitting element driving apparatus of the present invention.
4A and 4B show an embodiment of a switching pattern combination method of the light emitting element driving apparatus of the present invention.
5A to 5E are graphs showing LED currents according to an embodiment of switching pattern mixing of the light emitting device driving apparatus of the present invention shown in FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The same or similar reference numerals are used throughout the drawings for portions having similar functions and functions.

In addition, in the entire specification, when a part is referred to as being 'connected' with another part, it is not only a case where it is directly connected, but also a case where it is indirectly connected with another element in between do.

Also, to include an element means to include other elements, not to exclude other elements unless specifically stated otherwise.

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

1 is a schematic configuration diagram of a light emitting element driving apparatus of the present invention.

Referring to FIG. 1, the light emitting device driving apparatus 100 of the present invention may include a driving controller 110 and a driver 120.

The driving control unit 110 may control the driving of the light emitting device 130, and the driving unit 120 may drive the light emitting device 130 under the control of the driving control unit 110.

The driving controller 110 may include an ADC 111, a controller 112, a duty setting unit 113, and a switching controller 114.

The ADC 111 may receive feedback of the driving power in the form of an analog signal supplied from the driver 120 to the light emitting device 130 and convert the feedback power into a digital signal.

The controller 112 may compare the voltage level included in the digital signal Dout from the ADC 111 with a preset reference voltage Dref and control the switching duty setting according to the comparison result. Here, the control unit 112 may receive the digital signal also the reference voltage (Dref) to process the voltage level of the digital signal from the ADC (111).

The duty setting unit 113 may store a plurality of switching patterns each having a preset duty in the lookup table, and the duty setting unit 113 may control the plurality of switching patterns according to control according to the comparison result of the control unit 112. You can set the switching duty by mixing. This will be described later in detail with reference to the accompanying drawings.

The switching controller 114 may provide a pulse width modulation (PWM) signal having a duty set by the duty setting unit 113 to control power switching of the driver 120.

The driving unit 120 may include a switching unit 121 and an output filter unit 122.

The switching unit 121 may include at least two switches S1 and S2 connected in series between the input power terminal receiving the input power Vin and the ground. The two switches S1 and S2 may be turned on / off according to the pulse width modulation signal from the switching controller 114 to switch the input power Vin to output the driving power.

The output filter unit 122 may filter the driving power from the switching unit 121 and output the filtered power to the light emitting device 130. To this end, the output filter unit 122 may include an inductor L and a capacitor C, and the inductor L and the capacitor C may form an LC filter to filter the driving power.

2 and 3 are views showing an embodiment of switching pattern mixing of the light emitting element driving apparatus of the present invention.

Referring to FIG. 2 together with FIG. 1, the duty setting unit 113 may include a first switching pattern Dc1 having a first duty preset in a lookup table and a second switching having a second duty different from the first duty. The pattern DC2 can be stored.

For example, when the switching duty of the first and second switching patterns Dc1 and Dc2 is the closest switching pattern that can be generated in hardware by the switching controller 114, the first and second switching patterns Dc1, In order to generate a switching pattern having a duty between Dc2), alternately generating the first and second switching patterns Dc1 and Dc2 as shown in FIG. Power switching of the driver 120 may be controlled by a switching pattern (Dc1 + Dc2) / 2 having a duty between (Dc1 and Dc2). Accordingly, the resolution of the switching controller 114 may have an effect of increasing by 1 bit.

Based on this, referring to FIG. 3, a switching pattern having a duty between the first and second switching patterns Dc1 and Dc2 by adjusting a ratio of the number of times of generating the first and second switching patterns Dc1 and Dc2. You can create multiple.

For example, when a ratio of the first and second switching patterns Dc1 and Dc2 is mixed and output as 1: 3, 2: 2, and 3: 1, the duty ratio between the first and second switching patterns Dc1 and Dc2 may be reduced. The switching of the power supply of the driver 120 may be controlled by a switching pattern of (Dc1 + 3 * Dc2) / 4, (Dc1 + Dc2) / 2, and (3 * Dc1 + Dc2) / 4. Accordingly, the resolution of the switching controller 114 may have an effect of increasing by 2 bits.

 In the case of forming the above-described switching pattern, the switching duty may be varied to additionally generate voltage ripple of the driving power supply.

4A and 4B are views showing an embodiment of a switching pattern combination method of the light emitting element driving apparatus of the present invention.

4A and 4B, in forming a switching pattern, a switching duty having a switching pattern mixing ratio of {Dc1, Dc1, Dc1, Dc1, Dc2, Dc2, Dc2, Dc2} is {Dc1, Dc2, Dc1, Dc2 , Dc1, Dc2, Dc1, Dc2} may be the same as the switching duty, but {Dc1, Dc2, Dc1, Dc2, Dc1, Dc2, Dc1, Dc2} is {Dc1, Dc1, Dc1, Dc1, Dc2, Dc2 Ripple having a notation frequency twice as high as that of Dc2 and Dc2} occurs, and as the ripple frequency increases, the device size of the inductor L and the capacitor C of the LC filter of the output filter 122 may be reduced. . That is, when the switching pattern is mixed as shown in FIG. 4B, the output ripple may be reduced.

The frequency of the output ripple may have a relationship as in the following equation.

(Equation)

f _ripple = f _sw / 2 ^M

Where f _ripple is the frequency of the output ripple, f _sw is a switching frequency of a PWM signal for controlling switching, and 2 ^M means that the switching controller 114 increases the resolution of the M bits to control the switching of the driver 120 with 2 ^M switching patterns.

5A to 5E are graphs illustrating LED currents according to embodiments of switching pattern mixing of the light emitting device driving apparatus of the present invention illustrated in FIG. 3.

5A and 5B, for example, when the switching controller 114 has an 8-bit resolution, the switching duty of the first switching pattern Dc1 is 77/256, and the second switching pattern Dc2 adjacent thereto. The switching duty of may be 78/256, wherein the current (ILED) flowing in the light emitting device, in particular the light emitting diode, may be measured at 402 mA and 422 mA, respectively.

At this time, in the case where the duty setting unit 113 mixes the switching patterns to additionally implement 2 bits of resolution, (Dc1 + 3 * Dc2) / 4, (between the duty of the first and second switching patterns Dc1 and Dc2), The current ILED flowing through the light emitting diode by the switching patterns Dc1 + Dc2) / 2 and (3 * Dc1 + Dc2) / 4 may be measured at 412 mA, 415 mA, and 419 mA, respectively.

That is, the current flowing through the light emitting diode can be controlled more precisely.

As described above, according to the present invention, a plurality of switching patterns each having a preset duty according to the difference between the voltage supplied to the light emitting diode and the reference voltage are mixed so that the resolution of the analog-digital converter or the pulse width modulation module is not adjusted. While controlling the LED current precisely, the limit cycle can be eliminated to eliminate ripple in the LED current.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100 ... LED Driver
110 ... Drive control
111 ... ADC
112.Control panel
113 ... Duty setting section
114 ... switching control
120.Driver
121.Switching part
122.Output filter unit
130 ... light emitting element

Claims (6)

A driving unit for switching the input power to supply driving power to the light emitting device; And
A driving controller controlling power switching of the driving unit by mixing a plurality of preset switching patterns according to a voltage difference between the voltage level of the driving power source and a preset reference voltage;
Light emitting element driving apparatus comprising a.
The method of claim 1, wherein the driving control unit
An ADC receiving the feedback of the driving power and converting the driving power into a digital signal;
A controller which compares the voltage level of the digital signal from the ADC with the reference voltage and controls the duty setting according to the comparison result;
A duty setting unit for setting a switching duty by mixing at least two switching patterns having a preset switching duty in units of a preset switching signal group under the control of the controller; And
Switching control unit for controlling the power switching duty of the driving unit in accordance with the control signal of the duty setting unit
Light emitting element driving apparatus comprising a.
The method of claim 2,
And the duty setting unit mixes a first switching pattern having a preset first switching duty and a second switching pattern having a second switching duty different from the first switching duty of the first switching pattern.
The method of claim 3,
And the duty setting unit mixes the first switching pattern and the second switching pattern at least once.
5. The method of claim 4,
And the duty setting unit alternately mixes the first switching pattern and the second switching pattern.
2. The apparatus of claim 1, wherein the driving unit
A switching unit for switching the input power according to the switching control of the driving control unit; And
An output filter for filtering the power switched by the switching unit
Light emitting element driving apparatus comprising a.

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