KR100640174B1 - Apparatus for dimming of the electrode-less fluorescent lamp using a high frequency resonant inverter - Google Patents

Abstract

The present invention uses induction discharge as a ferromagnetic field without using a separate electrode, which ensures a long life and at the same time, a high frequency resonant inverter control device for dimming control of an electrodeless fluorescent lamp having a highly stable light emission characteristic even with a change in ballast output. In particular, in the inverter control device, the first counter for dividing the clock signal corresponding to one tenth of the basic switching frequency for driving the electrodeless fluorescent lamp; A first comparator for comparing a magnitude value of the first counter BCD value of a duty instruction commanded from the outside with a binary coded decimal (BCD) of 2 digits from the outside; An adder that adds 1 to the tenth digit of the duty command commanded from the outside; A multiplexer for selecting one of an output of the adder and a place value of 1 of a duty command commanded from the outside according to the output of the first comparator; A second counter for dividing the basic switching clock signal CLK for driving the electrodeless fluorescent lamp by 10; A second comparator comparing the output value of the multiplexer with the size of the second counter and outputting a switching enable signal T _EN corresponding to a period for driving the electrodeless fluorescent lamp; Inputting the basic switching clock signal CLK for driving the electrodeless fluorescent lamp and erasing the front part of the basic switching clock signal CLK for a period corresponding to the dead time to be inserted for preventing the short circuit of the inverter. A first idle period insertion circuit; A basic switching clock signal inverted by a period corresponding to a dead time to be inserted to prevent an inverter short circuit by receiving an inverted signal (/ CLK) of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp. A second rest period insertion circuit for erasing the front part of (/ CLK); A first AND gate outputting a phase-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the second comparator and the output of the first idle period insertion circuit; A second AND gate for outputting the lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN and the output of the second idle period insertion circuit; In this way, the driving time of the electrodeless fluorescent lamp can be controlled in units of 1% according to the digitally commanded duty command, thereby implementing a new burst dimming technique that can control the illuminance of the electrodeless fluorescent lamp almost continuously. High frequency resonant inverter control device for electrode fluorescent lamp dimming control.

Description

High Frequency Resonant Inverter Controller for Electrodeless Fluorescent Lamp Dimming Control {APPARATUS FOR DIMMING OF THE ELECTRODE-LESS FLUORESCENT LAMP USING A HIGH FREQUENCY RESONANT INVERTER}

1 is a view illustrating the structure and lighting principle of a typical electrodeless fluorescent lamp.

FIG. 2 shows an equivalent circuit of the electrodeless fluorescent lamp of FIG. 1.

3A and 3B are circuit diagrams and equivalent circuit diagrams illustrating a resonant inverter for an electrodeless fluorescent lamp applied to the present invention.

4A and 4B are circuit block diagrams and time charts illustrating an inverter control apparatus to which a burst dimming algorithm is applied according to an embodiment of the present invention.

5A and 5B are circuit block diagrams and time charts illustrating an inverter control apparatus to which a burst dimming algorithm is applied according to another embodiment of the present invention.

6A to 6D are graphs illustrating driving signals and resonance currents according to changes in fertilization rate according to an embodiment of the present invention.

7A to 7D are graphs showing lamp voltages and currents according to changes in fertilization rate according to an embodiment of the present invention.

8A to 8D are diagrams illustrating a dimming state of a lamp according to a change in fertilization ratio according to an embodiment of the present invention.

9A and 9B are graphs of input power and luminous flux according to the ratio of the burst dimming and the burst PWM average ratio ratio control according to the embodiment of the present invention.

10A and 10B are graphs showing light efficiency versus maximum input power illustrating a case where burst dimming and burst PWM average fertilization rate control according to an embodiment of the present invention are applied.

* Explanation of symbols for the main parts of the drawings

CNT: Counter CMP # 1: First Comparator

CMP # 2: 2nd comparator Deadtime 1: 1st idle period insertion circuit

Deadtime 2: Second idle period insertion circuit G1: First end gate

G2: second and gate CNT # 1: first counter

CNT # 2: second counter ADD: adder

MUX: Multiplexer

The present invention relates to a resonant inverter for lamps. In particular, unlike conventional fluorescent lamps, high frequency voltage from an external inverter in an electrodeless fluorescent lamp equipped with a ferrite core wound with a coil instead of an electrode on the outside of a gas-filled discharge tube. The present invention relates to a high frequency resonant inverter control device for an electrodeless fluorescent lamp dimming control for generating a magnetic field in the lamp to excite the encapsulated gas inside the discharge tube to emit light.

Recently, the interest and invention of the dimming control technique for reducing the power consumption by actively controlling the light output of the lamp in accordance with the ambient conditions such as natural lighting in the place where large-scale lighting facilities such as large buildings, tunnels and factories are installed It is becoming.

Fluorescent lamps used for most indoor lighting sources have the advantages of superior light quality, high efficiency, and very long life compared to incandescent lamps.However, when lighting requires a separate ballast and a voltage other than the rated voltage is applied, Since the unlit phenomenon due to the blackening due to deterioration occurs, the lamp life is sharply reduced.

Such a disadvantage is the biggest factor preventing the dimming control of fluorescent lamps, and the dimming control system for indoor lighting has not been put to practical use.

Electrodeless fluorescent lamps, which guarantee continuous lighting time of more than 60,000 hours, are not widely used at present due to high price and technical monopoly of a specific company, but conventional fluorescent lamps are used for thermoelectrics generated by electric fields between the electrodes of lamps. Unlike the phosphor emitting light, the lamp is turned on by a strong magnetic field generated by a coil mounted inside or outside the lamp.

Therefore, the blackening phenomenon, which has the greatest influence in determining the lifespan of a conventional fluorescent lamp, can be avoided in an electrodeless fluorescent lamp. Thus, the superiority of the conventional fluorescent lamp in terms of size, lifespan, and output has been confirmed. The spread of induction fluorescent lamps and dimming control have emerged as an urgent problem.

Accordingly, an object of the present invention is a high frequency resonant inverter control device for dimming control of an electrodeless fluorescent lamp having a long life and very strong characteristics against a change in ballast output since the electrodeless fluorescent lamp using induction discharge does not require an electrode. To provide.

It is another object of the present invention that the main circuit of the resonant inverter uses a half-bridge method to switch the two switches driven by a high frequency pulse of 250 kHz at a rate of 50% by using pulse width modulation of a frequency lower than the switching frequency. The present invention provides a high frequency resonant inverter control device for electrodeless fluorescent lamp dimming control based on a burst dimming technique.

Another object of the present invention is based on a burst dimming technique, which is mainly applied to dimming control of an LCD backlight, and the dimming can be controlled at a ratio of 5% through a control circuit using a simple digital logic circuit. It is to provide a high frequency resonant inverter control device for the electrodeless fluorescent lamp dimming control.

Another object of the present invention is based on a burst dimming technique, which is mainly applied to dimming control of LCD backlight, and is a burst PWM average ratio ratio control technique. The present invention provides a high frequency resonant inverter control device for dimming control of an electrodeless fluorescent lamp having dimming control at a ratio of.

The technical means of the present invention for achieving the above object is an inverter control device for an electrodeless fluorescent lamp dimming control: the first divided by 10 divided clock signal corresponding to one tenth of the basic switching frequency for driving the electrodeless fluorescent lamp 1 counter; A first comparator for comparing a magnitude value of the first counter BCD value of a duty instruction commanded from the outside with a binary coded decimal (BCD) of 2 digits from the outside; An adder that adds 1 to the tenth digit of the duty command commanded from the outside; A multiplexer for selecting one of an output of the adder and a place value of 1 of a duty command commanded from the outside according to the output of the first comparator; A second counter for dividing the basic switching clock signal CLK for driving the electrodeless fluorescent lamp by 10; A second comparator comparing the output value of the multiplexer with the size of the second counter and outputting a switching enable signal T _EN corresponding to a period for driving the electrodeless fluorescent lamp; Inputting the basic switching clock signal CLK for driving the electrodeless fluorescent lamp and erasing the front part of the basic switching clock signal CLK for a period corresponding to the dead time to be inserted for preventing the short circuit of the inverter. A first idle period insertion circuit; A basic switching clock signal inverted by a period corresponding to a dead time to be inserted in order to prevent a short circuit of the inverter by receiving the inversion signal / CLK of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp. A second rest period insertion circuit for erasing the front part of (/ CLK); A first AND gate outputting a phase-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the second comparator and the output of the first idle period insertion circuit; And a second AND gate which outputs a lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the second comparator and the output of the second idle period insertion circuit. It characterized by consisting of;

Specifically, the first and second counters are decimal counters (MOD-10), wherein the first and second end gates convert the basic switching clock signal of a predetermined frequency during the ratio ratio of the dimming PWM signal. It is characterized by generating only a switching signal.

In addition, another technical means of the present invention for achieving the above object is an inverter control device for an electrodeless fluorescent lamp dimming control comprising: a counter for counting a basic switching clock signal for driving an electrodeless fluorescent lamp; A first comparator for comparing the count data of the counter with a magnitude of PWM duration data commanded from the outside; A second comparator for comparing the count data of the counter with a duty ratio data commanded from the outside; A switching enable signal corresponding to a period for receiving a signal output from the first comparator and the second comparator, which is set at the rising edge of the first comparator and reset at the rising edge of the second comparator to drive the electrodeless fluorescent lamp ( An SR latch for outputting T _EN ); When the basic switching clock signal CLK for driving the electrodeless fluorescent lamp is input, the front part of the basic switching clock signal CLK is erased for a period corresponding to the dead time to be inserted in order to prevent the short circuit of the inverter. A first idle period insertion circuit; A basic switching clock signal inverted by a period corresponding to a dead time to be inserted in order to prevent a short circuit of the inverter by receiving the inversion signal / CLK of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp. A second rest period insertion circuit for erasing the front part of (/ CLK); A first AND gate outputting an upper-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the SR latch and the output of the first idle period insertion circuit; And a second AND gate outputting a lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the SR latch and the output of the second idle period insertion circuit. Characterized in that consisting of.

In addition, the first and second end gates generate the switching signal only during the ratio ratio of the dimming PWM signal to the basic switching clock signal of a predetermined frequency.

In addition, the ratio D of the PWM period signal Ts obtained by dividing the reference switching clock signal CLK at a predetermined frequency may be determined to generate a dimming PWM signal.

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

1 is a conceptual diagram illustrating a structure and a lighting principle of a general electrodeless fluorescent lamp, and FIG. 2 is an equivalent circuit diagram of the electrodeless fluorescent lamp.

Unlike conventional fluorescent lamps, a ferrite core with a coil wound instead of an electrode on the outside of a discharge tube filled with gas. When a high frequency voltage is applied from an external inverter, a magnetic field is formed in the lamp to excite the contained gas inside the discharge tube to emit light. As a light source, it has a long service life compared to a conventional fluorescent lamp, and is compact and suitable for high power. In addition, instantaneous lighting is achieved, and excellent luminous flux and efficiency, light color, temperature characteristics, and the like.

In this way, the electrodeless fluorescent lamp is turned on by applying a high frequency high voltage to the induction coil. The discharge tube is treated as no load until the discharge is started, while the discharge can be regarded as an equivalent pure resistance.

If the coupling coefficient between the induction coil and the discharge tube is k, the equivalent resistance of the discharge tube is Rp, and the number of windings of the induction coil is n, the electrodeless fluorescent lamp and the induction coil are the equivalent circuits in which the resistance Rp is connected to the air core transformer of n1. It may be displayed, and this may be represented as shown in FIG. 2.

From the equivalent circuit of FIG. 2, the impedances ZL of the ends b and c of the induction coil may be obtained as in Equation 1 below.

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In Equation 1, Lo is an excitation inductance seen from the b and c terminals, and ω _s represents the switching angular frequency.

In order to facilitate the analysis, the impedance ZL may be represented by Equation 2 below when the resistance R and the inductance Lr are connected in parallel.

3A and 3B are a basic circuit and an equivalent circuit diagram showing a high-frequency resonant inverter for an electrodeless fluorescent lamp of a half-bridge type applied to the present invention, wherein switches Q1 and Q2 are zero at both turn-on and turn-off times. Voltage switching is achieved to prevent switching losses.

When the parallel resonance frequency f _ox and the series resonance frequency f _rx are obtained from the reactance X of the entire resonance circuit including the resonance inductor L before the induction fluorescent lamp is turned on, Equation 3 is obtained.

In the same way, after calculating the parallel resonance frequency fo and the series resonance frequency fr after lighting, the following equation (4) is obtained.

In the circuit of FIG. 3A, if the value of the inverter capacitor Cs is sufficiently large, the voltage applied to the resonant circuit as in the equivalent circuit of FIG. 3B may be replaced by a square wave AC power source Vi from which the DC component is removed.

When the switching frequency is close to the series resonant frequency, the impedance of the resonant circuit is the smallest with respect to the switching frequency which is the fundamental wave component, and has a relatively very large impedance with respect to the harmonic component. That is, the circuit can be interpreted as a circuit in which the square wave AC power is replaced with the sine wave AC power in consideration of only the fundamental wave components. Therefore, the voltage at both ends of the resonant circuit can be expressed by Equation 5 below.

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The voltage at both ends of the lamp at this time v _c (t) is obtained as shown in Equation 6 below.

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The current i (t) flowing through the inductor L is obtained as shown in Equation 7 below.

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The voltage v _cx (t) and the inductor current ix (t) of the lamp before the lighting are calculated as shown in Equation 8 below by substituting R = ∞ in Equations 6 and 7.

Two algorithms are proposed for dimming control of an electrodeless fluorescent lamp employing a high frequency resonant inverter operating as described above. The proposed methods are basically burst dimming which is mainly used for CCFL dimming control for LCD backlights. ) Is based on the technique.

However, in general, the burst dimming method for a CCFL having a low rated power of several watts (W) cannot be applied to a discharge lamp of several hundred watts (W). In particular, the switching frequency of the resonant inverter for the CCFL is in the range of approximately 50 to 70 kHz and the dimming control burst dimming frequency is very low in the hundreds of Hz band.

Therefore, when the general burst dimming technique is applied to an electrodeless fluorescent lamp which is switched on at 250 kHz switching operation, not only the noise generated by the inductor vibration in the audible frequency range but also the continuous lamp re-ignition operation The fall of light efficiency is inevitable.

Accordingly, in the present invention, the dimming PWM frequency in the dimming control algorithm is selected to be about 1/10 times the frequency of the 250kHz switching frequency of the resonant inverter to avoid noise in the audible frequency band.

Then, look at the burst dimming algorithm, the basic principle is to operate the basic switching pulse of a constant frequency only during the period (D) of the dimming PWM signal, to generate a switching signal to control the average power of the inverter output side to control the illuminance of the lamp It's a way of control.

In the proposed scheme, if the frequency of the dimming PWM signal is too low, noise may occur due to vibration of the inductor in the audible frequency region.

Thus, the dimming PWM signal must be controlled over the audible frequency domain.

In addition, the switch operation of the resonant inverter always shows the time difference between the two switch turn-on and turn-off signals with the ratio (D) signal to stabilize the resonance current and ensure zero voltage switching during the interruption of the switches according to the PWM signal. It is desirable to synchronize.

It is very difficult and practical to configure analog control circuits that meet these conditions.

Therefore, in the present invention, a digital control circuit is constructed.

4A and 4B are circuit block diagrams illustrating an inverter control apparatus of a burst dimming algorithm and a time chart thereof according to an embodiment of the present invention, and include a counter CNT, a first comparator CMP # 1, and a second comparator ( CMP # 2), SR latch, first end gate G1, second end gate G2, and the like.

The counter CNT is configured to count the basic switching clock signal CLK for driving the electrodeless fluorescent lamp, and the first comparator CMP # 1 has the count data of the counter CNT and the PWM period commanded from the outside. The second comparator CMP # 2 is configured to compare the magnitude of the counter data CNT and the duty ratio data commanded from the outside. SR latch receives a signal output from the first comparator (CMP # 1) and the second comparator (CMP # 2), but is set at the rising edge of the first comparator (CMP # 1) and the second comparator (CMP #). 2) the switching enable signal T _EN corresponding to the period of reset and driving the electrodeless fluorescent lamp is reset at the rising edge of 2), and the first idle period insertion circuit Deadtime 1 is an electrodeless fluorescent lamp. Receive the basic switching clock signal (CLK) for driving It is configured to erase the front part of the basic switching clock signal CLK by a period corresponding to a dead time to be inserted for preventing a short circuit of the inverter, and the second idle period insertion circuit Deadtime 2 is electrodeless. A basic switching clock signal (/) inverted by a period corresponding to a dead time to be inserted to receive an inverted signal (CLK) of the basic switching clock signal CLK for driving a fluorescent lamp to prevent a short circuit of the inverter. And the first AND gate G1 takes a logical product of the switching enable signal T _EN , which is the output of the SR latch, and the output of the first idle period insertion circuit Deadtime 1. It is configured to output the phase-arm switching signal Q1 of the inverter for driving an electrodeless fluorescent lamp, and the second AND gate G2 inserts the switching enable signal T _EN , which is the output of the SR latch, and the second dwell period. Circuit (Deadtime 2) The output of the lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter is obtained by taking the logical product of the output.

In addition, drive switches Q1 and Q2 of the inverter shown in FIG. 3A are respectively provided at the output terminals of the first and second AND gates G1 and G2, and the plurality of drive switches Q1 and Q2 are provided. The switch is operated according to a point / light off control or a dimming control signal having a predetermined ratio through the output terminals of the first and second end gates G1 and G2 to control the power applied to the electrodeless fluorescent lamp. Done.

In addition, the first AND gate G1 and the second AND gate G2 have an appropriate dead time to prevent a dark short between the PWM switching signal T _EN of the SR latch, which is an input signal, and the basic switching clock signal CLK. It is configured to be provided through.

In the inverter controller configured as described above, the basic switching clock is 250 kHz, and the clock signal is counted using the counter CNT to determine the values of the predetermined PWM cycle signal Ts and the ratio D and the digital comparator CMP # 1, Compared with CMP # 2), the SR latch is operated to generate the switching period signal T _EN .

Here, the fertilization rate (D) is defined as in Equation 9 below.

The drive signal of the switches Q1 and Q2 of the resonant inverter is made by performing a logical product of the basic switching clock signal CLK and the inverted signal / CLK of this signal with respect to the switching section signal T _EN . At this time, an appropriate dead time must be added between the two signals CLK and T _EN to prevent dark short.

In FIG. 4A, if the PWM signal information is determined to be 25 kHz, which is 1/10 of the switching frequency, the rate of application may be controlled in units of 10%. If more precise illuminance control is required, control can be performed in units of 5% by controlling switch Q1 of FIG. 3A to operate once more than switch Q2.

However, this control method is relatively economical because it has a simple control circuit configuration, but the dimming control range of the resonant inverter is limited to a maximum of 5%.

4A and 4B, a more precise dimming control algorithm is proposed as shown in FIG.

5A and 5B are circuit block diagrams illustrating an inverter control apparatus of a burst dimming algorithm according to another embodiment of the present invention and a time chart thereof, and include a first counter (CNT # 1), a first comparator (CMP # 1), An adder ADD, a multiplexer MUX, a second counter CNT # 2, a second comparator CMP # 2, a first end gate G1, a second end gate G2, and the like.

The first counter CNT # 1 is configured to divide the clock signal corresponding to one tenth of the basic switching frequency for driving the electrodeless fluorescent lamp, and the first comparator CMP # 1 is configured to divide the first counter. It is configured to compare the count value of (CNT # 1) with the magnitude of the first digit BCD value of the duty instruction commanded from the external 2-digit Binary Coded Decimal (BCD). ADD) is configured to add 1 to the 10th digit value of the duty command commanded from the outside, and the multiplexer MUX is the output of the adder ADD and the 1st place of the duty command commanded from the outside. One of the values is configured to be selected according to the output of the first comparator CMP # 1, and the second counter CNT # 2 divides the basic switching clock signal CLK for driving the electrodeless fluorescent lamp by 10 minutes. The second comparator CMP # 2 is configured to match the output value of the multiplexer MUX. Second counter by comparing the size of the (CNT # 2) is configured to output a switching enable signal (T _EN) for the period of driving the electrodeless fluorescent lamp, the first idle period inserted circuit (Deadtime 1) is To receive the basic switching clock signal CLK for driving the electrodeless fluorescent lamp and to erase the front part of the basic switching clock signal CLK by a period corresponding to the dead time to be inserted for preventing the short circuit of the inverter. The second idle period insertion circuit Deadtime 2 receives an inverted signal / CLK of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp and is inserted for preventing a short circuit of the inverter. And a front part of the basic switching clock signal / CLK inverted by a period corresponding to (Dead Time), and the first AND gate G1 is a switching-in output which is an output of the second comparator CMP # 2. Able signal (T _EN ) and the above It is configured to output the phase-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking the logical product of the output of the first idle period insertion circuit Deadtime 1, and the second end gate G2 is the second comparator CMP #. 2) and outputs the lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking the logical product of the switching enable signal T _EN and the output of the second idle period insertion circuit Deadtime 2. .

In addition, drive switches Q1 and Q2 of the inverter shown in FIG. 3A are respectively provided at the output terminals of the first and second AND gates G1 and G2, and the plurality of drive switches Q1 and Q2 are provided. Are switched to the electrodeless fluorescent lamps according to the point / light-out control or dimming control signals having a predetermined ratio D through the output terminals of the first and second gates G1 and G2. The power is controlled.

In addition, the first and second counters CNT # 1 and CNT # 2 are decimal counters MOD-10, and the first and second gates G1 and G2 are input signals. In order to prevent a short circuit between the PWM switching signal T _EN and the basic switching clock signal CLK of the second comparator CMP # 2, the controller is configured to be provided with an appropriate dead time.

The burst PWM average fertilization rate control algorithm configured as described above is capable of much more precise dimming control than the burst dimming method proposed in FIGS. 4A and 4B.

In the block circuit diagram of FIG. 5A, the basic switching frequency is 250 kHz, and the clock pulse divided by 1/10 of the basic switching frequency is counted using a decimal counter (MOD-10). Precise dimming control is possible.

The counters CNT # 1 and CNT # 2 are sequential circuits that receive input pulses and repeat states in a predetermined order. The first counter CNT # 1 receives a value counting a pulse signal of 25 kHz from an external controller. It is used as a control signal of the multiplexer (MUX) in comparison with the BCD code corresponding to one digit value.

The output of the multiplexer (MUX) by the control signal generated from the first comparator (CMP # 1) is the first comparator (CMP) of the 10-digit BCD code input from the external controller and a value larger than this value by 1 It is selectively switched in accordance with the condition of # 1) and supplied to the B input terminal of the second comparator CMP # 2.

In addition, the second comparator CMP # 2 receives a value obtained by counting the basic switching frequency by the second counter CNT # 2 to the A input terminal, and compares it with an output signal of the multiplexer MUX to activate the signal DA. Or DB). As a result, the drive signals of the inverter switches Q1 and Q2 can be output only when this activation signal DA or DB occurs.

The dimming control algorithm is more clearly explained through the time chart of FIG. 5B. In FIG. 5B, if T is 10Ts and T is TA + TB, the application rate through the proposed burst PWM average application rate control algorithm may be defined as follows.

Example

Based on the proposed dimming control technique, a resonant inverter for an electrodeless fluorescent lamp was fabricated. The main parameters applied to the manufactured resonant inverter are as follows.

Vdc: 400 [V], switching frequency (fs): 250 [kHz], Q1 / Q2: IRF840 (500V, 8A), resonant inductor (L): 232 [uH], capacitor (Cs): 100 [nF], Capacitor (Cp): 2.2 [nF], basic resonant frequency (fr): 222.77 [kHz], Lamp: Endura 100W (Osram).

6 shows a change in the switching pattern and the current i _r flowing through the resonant circuit when the two dimming techniques proposed by the present invention are applied.

As shown in FIGS. 6A to 6C, the resonant current in the region of 50% or more ratio is controlled without difficulty, whereas the resonant current fluctuates rapidly during the intermittent period as shown in FIG. 6D. The ringing phenomenon also increases.

The waveforms of the ramp voltage and the lamp current with respect to the change in the fertilization rate D are shown in FIG. 7.

Like the above-mentioned resonant current change, lamp voltage and lamp current also show relatively stable changes when the ratio is large, but severe fluctuations occur in the region where the ratio is very small. However, unlike the waveform of the resonance current during the intermittent period, it can be seen that the waveform remains relatively stable without severe ringing phenomenon.

The photograph of observing the dimming state of the lamp according to the change of the fertilization ratio (D) is shown in FIG. 8, and it can be seen that the dimming of the lamp is well controlled according to the change of the fertilization ratio (D).

9 is a graph showing a change ratio of the inverter input power and the change rate of the lamp luminous flux with respect to the change of the fertilization rate (D) according to the two proposed schemes.

As a result of the experiment, 50% of the luminous flux was measured at the application rate of about 35%, and the input power change ratio and the lamp luminous flux change ratio were almost the same at the application rate of 35% or more, but the input power was changed in the lower range. Compared to the above, it can be seen that the change in the speed of light is severe.

In particular, when applying the burst dimming method as shown in Figure 9a, inaccurate dimming control of 5% is achieved, this disadvantage makes it difficult to control the dimming, especially in low illuminance range.

On the other hand, in the dimming control to which the burst PWM average fertilization rate control of FIG. 9B is applied, precise illuminance control in units of 1% is possible, so that the change in the luminous flux can be precisely controlled even in a low ratio range.

This characteristic can be more clearly confirmed through a graph of light efficiency versus maximum input power of FIG. 10.

When the burst dimming method of 5% is applied through FIG. 7A, the optical efficiency to the maximum input power decreases rapidly at the application rate of 0.4 or less, and the control ratio of the 5% unit is the power side regeneration occurring at the end of the switching operation. The low power factor operation is performed due to the mode, and thus, the change in the light efficiency compared to the maximum input power occurs badly even at the application ratio of 0.4 or more.

On the other hand, when the burst PWM average fertilization rate control is applied, the light efficiency is severely changed in the range of 0.4 or less, but it can be seen that smooth control is possible in the 1% unit ratio. In addition, even when the application rate of 0.4 or more, improved burst dimming technique can achieve a very stable light efficiency compared to the maximum input power.

However, both methods can maintain an efficiency of 90% or more relative to the rating for the application rate of more than 35% of the maximum value, and apply the burst dimming than the continuous operation at the application rate of 1, the maximum when operating in the application rate of 0.4 to 0.8 section. The light efficiency compared to the input power was observed rather high.

Therefore, in the present invention, two types of electrodeless fluorescent lamp dimming control algorithms are proposed, and the two dimming control algorithms are as follows.

First is a burst dimming technique that controls a switch driven by a high frequency pulse of 250 kHz with a PWM modulation waveform that is much lower than the switching frequency to control on and off. Second, it generates 10 PWMs and adjusts the ratio of this PWM signal accordingly. This is a burst PWM average rate control method that enables precise dimming control in units of 1% by controlling.

The first method is economical because the control circuit configuration is simple, but the dimming control range is controlled in units of up to 5%, there is a disadvantage that it is not possible to precisely adjust the illumination at a low ratio.

In the second method, precise dimming control in units of 1% is possible, so that relatively precise illuminance control is possible even at a low ratio, but the configuration of the control circuit is somewhat complicated.

However, in both experiments, we obtained 50% of luminous flux at the highest value at 35% application rate, and the optical efficiency compared to the input power was higher than the maximum input power over 90% for the input power over 35% of the maximum input power. Could get

While specific embodiments of the present invention have been described and illustrated above, it will be apparent that the present invention may be embodied in various modifications by those skilled in the art. Such modified embodiments should not be understood individually from the technical spirit or the prospect of the present invention, but should fall within the claims appended to the present invention.

Therefore, in the present invention, the electrodeless fluorescent lamp using induction discharge has a long lifetime because it does not require an electrode, and a high frequency resonant inverter control device for dimming control of an electrodeless fluorescent lamp having a very strong characteristic against a change in ballast output is provided. Can provide.

In addition, by using a digital logic circuit, the burst dimming PWM on duty can be finely controlled in units of 1% in synchronization with the basic switching period of the electrodeless fluorescent lamp, thereby enabling almost continuous illumination control.

Claims (6)

In the inverter control device for induction fluorescent lamp dimming control: A first counter for dividing a clock signal corresponding to one tenth of a basic switching frequency for driving an electrodeless fluorescent lamp by 10; A first comparator for comparing a magnitude value of the first counter BCD value of a duty instruction commanded from the outside with a binary coded decimal (BCD) of 2 digits from the outside; An adder that adds 1 to the tenth digit of the duty command commanded from the outside; A multiplexer for selecting one of an output of the adder and a place value of 1 of a duty command commanded from the outside according to the output of the first comparator; A second counter for dividing the basic switching clock signal CLK for driving the electrodeless fluorescent lamp by 10; A second comparator comparing the output value of the multiplexer with the size of the second counter and outputting a switching enable signal T _EN corresponding to a period for driving the electrodeless fluorescent lamp; Inputting the basic switching clock signal CLK for driving the electrodeless fluorescent lamp and erasing the front part of the basic switching clock signal CLK for a period corresponding to the dead time to be inserted for preventing the short circuit of the inverter. A first idle period insertion circuit; A basic switching clock signal inverted by a period corresponding to a dead time to be inserted in order to prevent a short circuit of the inverter by receiving the inversion signal / CLK of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp. A second rest period insertion circuit for erasing the front part of (/ CLK); A first AND gate outputting a phase-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the second comparator and the output of the first idle period insertion circuit; And A second AND gate outputting a lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the second comparator and the output of the second idle period insertion circuit; Electromagnetic fluorescent lamp dimming control high frequency resonant inverter control device comprising a. The method according to claim 1, And the first and second counters are decimal counters (MOD-10). The method according to claim 1, The first and second end gates generate the switching signal only during the period of the ratio of the dimming PWM signal to the basic switching clock signal having a predetermined frequency, and the burst PWM average ratio D is determined by Equation 11 below. A high frequency resonant inverter control device for an electrodeless fluorescent lamp dimming control, characterized in that.

T is 10 * Ts and T is TA + TB. In the inverter control device for induction fluorescent lamp dimming control: A counter for counting a basic switching clock signal for driving an electrodeless fluorescent lamp; A first comparator for comparing the count data of the counter with a magnitude of PWM duration data commanded from the outside; A second comparator for comparing the count data of the counter with a duty ratio data commanded from the outside; A switching enable signal corresponding to a period for receiving a signal output from the first comparator and the second comparator, which is set at the rising edge of the first comparator and reset at the rising edge of the second comparator to drive the electrodeless fluorescent lamp. An SR latch outputting (T _EN ); Inputting the basic switching clock signal CLK for driving the electrodeless fluorescent lamp and erasing the front part of the basic switching clock signal CLK for a period corresponding to the dead time to be inserted for preventing the short circuit of the inverter. A first idle period insertion circuit; A basic switching clock signal inverted by a period corresponding to a dead time to be inserted in order to prevent a short circuit of the inverter by receiving the inversion signal / CLK of the basic switching clock signal CLK for driving an electrodeless fluorescent lamp. A second rest period insertion circuit for erasing the front part of (/ CLK); A first AND gate outputting an upper-arm switching signal Q1 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN output of the SR latch and the output of the first idle period insertion circuit; And A second AND gate outputting the lower arm switching signal Q2 of the electrodeless fluorescent lamp driving inverter by taking a logical product of the switching enable signal T _EN and the output of the second idle period insertion circuit; High frequency resonant inverter control device for electrodeless fluorescent lamp dimming control comprising a. The method according to claim 4, The first and second AND gates generate the switching signal only during the ratio ratio of the dimming PWM signal to the basic switching clock signal of a predetermined frequency, wherein the ratio D is determined by Equation 12 below. A high-frequency resonant inverter control device for electrodeless fluorescent lamp dimming control.

However, T _EN is a switching enable signal T _EN corresponding to a period for driving an electrodeless fluorescent lamp which is an output of an SR latch, and Ts is a PWM cycle signal. The method according to claim 4, A high frequency resonant inverter for dimming control of an electrodeless fluorescent lamp, characterized in that the dimming PWM signal is generated by determining the ratio D of the PWM period signal Ts divided by the reference switching clock signal CLK at a predetermined frequency. controller.

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