JP6616763B2 - Dimming control method of induction lamp using half bridge circuit and dimming ballast - Google Patents

Description

  The present invention relates to a method for controlling the dimming of an induction lamp and a dimming ballast using a half-bridge circuit, and more particularly, using a high / low method instead of a burst-on / off method, Method for controlling dimming of induction lamp and half-bridge circuit capable of stably performing dimming control of induction lamp by controlling so that induction lamp is turned off while maintaining low output when It relates to dimming ballast using

In recent years, dimming control system that reduces power consumption by controlling the light output of the lamp according to the surrounding conditions such as natural illuminance in places where large lighting equipment is installed such as large buildings, tunnels, factories, etc. Is being actively devised and devised.
In the conventional fluorescent lamp, the fluorescent substance emits light by the thermoelectrons generated by the electric field between the electrodes throughout the fluorescent lamp. On the other hand, an induction lamp that is turned on by a strong magnetic field generated from a coil disposed inside or outside is known.

  Therefore, the induction lamp can avoid the blackening phenomenon that has the greatest influence on the determination of the lifetime of the conventional fluorescent lamp. Unlike a fluorescent lamp, an induction lamp is a lamp in which a ferrite core in which a coil is wound instead of an electrode is provided outside a discharge tube in which a gas is sealed. An induction lamp is a light source that emits light when a high-frequency voltage is applied from an external inverter and a magnetic field is formed in the induction lamp and the gas enclosed in the discharge tube is excited. The induction lamp has a longer life and is smaller than existing fluorescent lamps, and is suitable for high output. Furthermore, the induction lamp is superior in terms of immediate on, total luminous flux, efficiency, photochromic characteristics, and temperature characteristics as compared with existing general fluorescent lamps.

  However, as described above, the induction lamp has some advantages over the conventionally known fluorescent lamps, but has an inconvenience that the output, that is, the luminance cannot be easily controlled. FIG. 1 shows a conventional circuit for driving an induction lamp. As shown in FIG. 1, the drive circuit converts the external input power supplies L and N into a specific DC voltage (for example, DC 400V) for driving the induction lamp and supplies the DC voltage ( Or PFC circuit) 10, two switching elements FET1 and FET2 connected in series to both output ends of the power supply circuit 10, and two switching elements FET1 and a plurality of specific frequencies from a plurality of frequencies in response to a lamp control signal. The control circuit 20 configured to switch the FET 2, the choke coil Choke, and the resonance capacitors C 1 and C 2 resonate the output signal at the intermediate point between the two switching elements FET 1 and FET 2, and supply this resonance output signal to the induction lamp 40. And a resonance circuit 30 configured to do so.

  In the conventional circuit configured as described above, the power supply circuit 10 converts an external common power supply into a DC power supply and supplies the DC power supply to the switching elements FET1 and FET2. The control circuit 20 switches on and off the induction lamp 40 according to the resonance state of the resonance circuit 30 by switching the switching elements FET1 and FET2 from a plurality of frequencies to a specific frequency.

  Such an induction lamp is a fluorescent lamp having no filament, and employs an indirect load method using an induction coil. Therefore, since the dimming control using the method of detecting the output transmitted to the induction lamp and controlling the feedback is impossible, the dimming method using the burst on / off method is used for dimming. There is a need. The luminance increases as the burst-on interval becomes longer, but decreases as the burst-on interval becomes shorter.

  FIG. 2A shows the dimming characteristics of the burst method in the conventional induction lamp, and FIG. 2B is a table showing the ballast operating characteristics of each on / off section in the conventional induction lamp. is there.

  As shown in the characteristic diagram of FIG. 2, the control circuit 20 controls the switching elements FET1 and FET2 to the on section A and the off section B by switching the frequencies of the switching elements FET1 and FET2 to a specific frequency. In the on section A, the switching elements FET1 and FET2 operate normally. However, in the off section B, as shown in FIG. 2, the control circuit 20 turns off the switching elements FET1 and FET2 by controlling the switching elements FET1 and FET2 so as to be in an all-off state where the voltage level is zero. To.

  That is, as shown in the table of FIG. 2B, in the on section A, the frequencies of the switching elements FET1 and FET2, that is, the high-side transistor and the low-side transistor are set to the frequency of 220 KHz for dimming control with a duty ratio of 50%. By controlling, the dimming control can be normally operated. On the other hand, in the off section B, the high side transistor and the low side transistor are all in the off state, and are controlled at the frequency “0” KHz (that is, in the off state).

Korean Patent No. 10-0825378

  In the conventional method, the dimming control is performed so that the ballast output is normally operated in the burst-on section A and the ballast output is completely turned off in the burst-off section B. For this reason, the ballast needs to be repeatedly turned on and off innumerably for dimming. As a result, damage to the ballast is increased, the operation of the circuit becomes unstable due to an increase in the off section, and the dimming range is narrowed.The induction lamp is turned off or the ballast is destroyed depending on the ambient temperature and the state of the induction lamp Reliability is very low.

  As described above, when the output of the induction lamp increases, dimming control becomes more difficult, and problems occur in either cold or warm weather conditions or situations where sudden dimming control is required. It is difficult to use.

  Therefore, the present invention uses the half-bridge technique for controlling the output by controlling both the frequency and the pulse width in Korean Patent No. 10-0825378 filed prior to the present application, so that burst dimming of the on / off method is performed. A method and a dimming ballast for controlling dimming of an induction lamp, which can solve the problems that occur during dimming of a conventional induction lamp by controlling burst dimming instead of the high / low method.

  A dimming control method for an induction lamp according to an embodiment of the present invention is a method for controlling dimming of an induction lamp using a half-bridge circuit, and uses a burst high / low method instead of a burst on / off method. The output is controlled. In this case, the resonance of the resonance circuit is maintained in the off section of the induction lamp and the switching frequency is increased so that the induction lamp is turned off, the switching gain of the high side transistor is reduced, and the switching of the low side transistor is performed. Gain increases.

  Therefore, it is a method of controlling the dimming of the induction lamp using a half-bridge circuit, and in response to the dimming signal, repeatedly controlling the on section where the induction lamp is on and the off section where the induction lamp is off. A method is provided that includes controlling the brightness of the induction lamp by controlling the gain of the on and off sections.

  In this case, in the on section, the induction lamp is turned on by controlling the high-side transistor and the low-side transistor of the half bridge circuit based on the first switching gain at the predetermined first resonance frequency.

  Further, in the off period, the half bridge circuit is configured based on the second switching gain preset lower than the first switching gain at the second resonant frequency preset higher than the first resonance frequency. At the same time as controlling the high-side transistor, the off-side period is controlled by controlling the low-side transistor based on a third switching gain preset higher than the first switching gain.

  Further, when the on period changes to the off period or when the off period changes to the on period, the switching frequency and switching gain of the high side transistor and the low side transistor are controlled so as to gradually change during a predetermined slope time. The

  The half-bridge circuit is used to control the dimming of the induction lamp. The output of the half-bridge circuit is connected to the resonance circuit, and the on / off of the induction lamp is controlled in response to the resonance of the resonance circuit. A method is provided wherein the brightness of the induction lamp is controlled by controlling the gain of the induction lamp on and off sections by control of the half-bridge circuit.

This method includes the following processes.
A luminance gain setting process for setting a length of a high section in which the guide lamp is turned on and a length of a low section in which the guide lamp is turned off in response to a dimming signal having a gain corresponding to the degree of brightness.

  A high-side transistor and a low-side transistor of a half-bridge circuit using a switching signal having a frequency of a first resonance frequency at which the resonance circuit resonates in a high section set in the switching gain and luminance gain setting process of the first switching gain High section control process for switching between.

  From the time when the high period ends, the switching signal frequency is increased from the first resonance frequency to the predetermined second resonance frequency, and at the same time, the switching gain of the high-side transistor of the half-bridge circuit is proportional to the increase in frequency. Is lowered to a predetermined second switching gain, and the switching control process of increasing the switching gain of the low-side transistor of the half-bridge circuit to the predetermined third switching gain in proportion to the increase in frequency.

  In the decrease interval control process, after changing the switching signal frequency and the switching gain of the high side and low side transistors to the set frequency and the setting switching gain, the switching signal is output for the length of the low interval set in the luminance gain setting process. The second resonance frequency with the set frequency is maintained, the second switching gain with the high-side transistor set is maintained, and the third switching gain with the set low-side transistor switching gain is maintained. A low interval control process for controlling to perform.

  The switching gain of the high-side transistor of the half bridge circuit is decreased in proportion to the decrease in the frequency at the same time as the frequency of the switching signal is lowered from the second resonance frequency to the first resonance frequency from the time when the low section control process is completed. Is increased from the second switching gain to the first switching gain, and the switching gain of the low-side transistor of the half-bridge circuit is decreased from the third switching gain to the first switching gain in proportion to the increase in frequency, An ascending zone control process that returns to the high zone control process after completion of frequency and switching gain changes.

  Furthermore, in one embodiment, a dimming ballast for an induction lamp is provided comprising:

  A bridge diode configured to receive AC power through a fuse and a line filter and to convert AC power to DC power.

  A DC stabilization unit configured to stabilize the DC power of the bridge diode using the reactor L, the diode D, and the capacitor C.

  A power factor correction (PFC) circuit configured to compensate for the power factor of the DC stabilization unit.

  A DC power supply unit configured to stabilize the DC output of the bridge diode to 5V DC power and output 5V DC power.

  A half-bridge circuit configured to receive DC power of a DC stabilization unit, switch received DC power via a serial connection between a high-side transistor and a low-side transistor, and output the switched DC power .

  A resonance circuit configured to receive an output of a half-bridge circuit and resonate the received output via a resonance coil L and a resonance capacitor C to turn on an induction lamp.

  Based on the dimming voltage, the gain of the high section in which the induction lamp is turned on and the gain of the low section in which the induction lamp is turned off are set based on the dimming voltage, and switching of the half bridge circuit in the high section and the low section A control device configured to set a frequency and a switching gain of a high side transistor and a low side transistor and to generate a control signal.

  Controlled by the controller, sets the switching frequency as the first set frequency, controls the high-side transistor and the low-side transistor of the half-bridge circuit based on the first switching gain in the high section, and sets the switching frequency to the second The high-side transistor of the half-bridge circuit is controlled based on the second switching gain set lower than the first switching gain and set higher than the first switching gain in the low section. A frequency / pulse width control half-bridge drive unit configured to control the low-side transistor based on the third switching gain provided.

  ADVANTAGE OF THE INVENTION According to the present invention, the dimming of the induction lamp can be controlled, which can solve the problems that occur when the conventional induction lamp is dimmed by the burst dimming control of the high / low method instead of the burst dimming of the on / off method. And a dimming ballast can be provided.

FIG. 1 shows a conventional circuit for driving an induction lamp. FIG. 2A shows the dimming characteristics of the burst method in the conventional induction lamp, and FIG. 2B is a table showing the ballast operating characteristics of each on / off section in the conventional induction lamp. is there. FIG. 3 is a block diagram of a dimming ballast for an induction lamp according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating a method for controlling dimming of an induction lamp using a half bridge circuit according to an embodiment of the present invention. FIG. 5A is a diagram showing the dimming characteristics of the high / low control method in the induction lamp according to the embodiment of the present invention, and FIG. 5B is the induction according to the embodiment of the present invention. It is the table | surface which showed the operational characteristic of the ballast of each area for the light control of a lamp | ramp.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a block diagram of a dimming ballast for an induction lamp according to an embodiment of the present invention.

The induction lamp which concerns on one Embodiment of this invention comprises the following.
A bridge diode 10 configured to receive AC power through a fuse and a line filter and to convert AC power to DC power.
A DC stabilization unit 20 configured to stabilize the DC power of the bridge diode 10 using the reactor L, the diode D, and the capacitor C.
A power factor correction (PFC) circuit 30 configured to compensate for the power factor of the DC stabilization unit 20.
A DC power supply unit 40 configured to stabilize the DC output of the bridge diode 10 to 5 V DC power and output 5 V DC power.
It is configured to receive the DC power of the DC stabilization unit 20, switch the received DC power via the serial connection between the high side transistor 51 and the low side transistor 52, and output the switched DC power. Half-bridge circuit 50;
A resonant circuit 60 configured to turn on the induction lamp 70 by receiving the output of the half-bridge circuit 50 and resonating the received output via the resonant coil L and the resonant capacitor C.
A half-bridge circuit that receives a dimming signal, sets a gain in a high section in which the induction lamp 70 is turned on and a gain in a low section in which the induction lamp 70 is turned off, based on a dimming voltage, and in the high section and the low section A control device 100 configured to set a switching frequency of 50 and a switching gain of the high-side transistor 51 and the low-side transistor 52 to generate a control signal.

  Controlled by the control device 100, the switching frequency is set as the first set frequency, the high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 are controlled based on the first switching gain in the high section, and switching is performed. The frequency is set as the second set frequency, and the high-side transistor 51 of the half-bridge circuit 50 is controlled based on the second switching gain set lower than the first switching gain, and the first in the low period is controlled. A frequency / pulse width control half-bridge drive unit 90 configured to control the low-side transistor 52 based on a third switching gain set higher than the switching gain. In this case, 80 is a protection circuit for the half-bridge circuit 50 and includes a known half-bridge circuit protection circuit.

  In the dimming control device for an induction lamp configured as described above according to an embodiment of the present invention, AC power is received. The bridge diode 10 rectifies AC power into DC power. The DC power is input to the half bridge circuit 50 through the DC stabilization unit 20. The high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 are controlled by a frequency / pulse width control half-bridge driving unit 90 controlled by the control device 100. The output of the half bridge circuit 50 is output to the resonance circuit 60, whereby the induction lamp 70 is turned on in response to the resonance of the resonance circuit 60. The frequency / pulse width control half-bridge drive unit 90 is a technique disclosed in Korean Patent No. 10-0825378. In one embodiment of the present invention, the frequency and pulse width are controlled by using the frequency / pulse width control half-bridge drive unit 90. The high side transistor 51 and the low side transistor 52 are separated and controlled in response to respective pulse width switching signals.

  In one embodiment of the present invention, control is performed using the burst high / low method instead of the burst on / off method. The frequency / pulse width control half bridge drive unit 90 controls the dimming of the induction lamp 70 by controlling the drive of the half bridge circuit 50. In this dimming control method, the control device 100 alternately repeats the high period in which the induction lamp is turned on and the low period in which the induction lamp is turned off, but the brightness of the induction lamp is based on the pulse gain in the high period and the low period. May be controlled.

  However, as shown in FIG. 2, in the conventional dimming control method, by controlling the high-side transistor and the low-side transistor based on the set frequency and the set switching gain in the on section where the induction lamp 70 is turned on, The induction lamp is turned on. In the off section where the induction lamp is turned off, the half-bridge circuit is controlled using all off signals having zero frequency and switching gain. Therefore, since the on section and the off section are repeatedly controlled at high speed, it is difficult to stably use the induction lamp.

  Therefore, in one embodiment of the present invention, the induction lamp can be turned off while maintaining the resonance of the resonance circuit 60 without turning off the output of the half-bridge circuit 50 in the off section where the induction lamp is turned off. By controlling the induction lamp 70 so as to have a low output state, the conventional problem can be solved.

  In the method for controlling dimming of the induction lamp using the half-bridge circuit according to one embodiment of the present invention, in response to the dimming signal, the on section in which the induction lamp is on and the off section in which the induction lamp is off. The brightness of the induction lamp is controlled by controlling the gain of the on section and the off section while repeatedly controlling the section.

  In this case, in the ON section, the induction lamp 70 controls the high-side transistor 51 and the low-side transistor 52 of the half bridge circuit 50 based on the first switching gain at the predetermined first resonance frequency, Turn on.

  In this case, in the off period, the half bridge circuit is based on the second switching gain preset lower than the first switching gain at the second resonant frequency preset higher than the first resonance frequency. At the same time as controlling the 50 high-side transistors 51, the off period is controlled by controlling the low-side transistor 52 based on a third switching gain that is preset higher than the first switching gain.

  In such an embodiment of the present invention, the half-bridge circuit 50 maintains the high-state output in the on-section and the low-state output in the off-section, so that the induction lamp 70 is turned on / off without the resonance circuit 60 being turned on / off. Both the switching frequency and switching pulse width of the half-bridge circuit 50 are controlled so that dimming can be controlled. A technique for simultaneously controlling the switching frequency and switching pulse width, ie, switching gain, of the half-bridge circuit 50 is disclosed in detail in Korean Patent No. 10-0825378 filed and registered by the applicant of the present invention. Therefore, detailed description of this technique is omitted.

  The high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 are switched to a specific resonance frequency, and the outputs of the high-side transistor 51 and the low-side transistor 52 are transmitted to the resonance circuit 60 and respond to the resonance of the resonance circuit 60. Thus, the induction lamp 70 is turned on.

  As in the prior art, in the on section in which the induction lamp 70 is on, the switching gain of the high side transistor 51 and the low side transistor 52 is 50 using a predetermined resonance frequency, that is, the first resonance frequency (for example, 200 KHz). Since the duty ratio is controlled to be the same as%, the ON section is controlled as a high section.

  In the off section in which the induction lamp 70 is turned off, the resonance circuit 60 is turned off by turning off the half-bridge circuit 50, so that dimming of the induction lamp is appropriately performed due to a problem caused by repeated on / off. Can not be controlled. Therefore, in one embodiment of the present invention, the half bridge circuit 50 is controlled so as to have a low output capable of turning off the induction lamp 70 while maintaining the resonance state of the resonance circuit 60.

  In the burst on / off method, that is, the known lamp dimming method, the existing technology does not cause a problem in the on period, that is, the high period. However, the existing section cannot generate a low section. Unlike known fluorescent lamps that employ the direct load method, the induction lamp has a structure that does not have a filament and employs the indirect load method using an induction coil. In the indirect load method, the operating frequency is increased to 200% in order to maintain low power with the induction lamp being off. In such a state, the resonance condition range between the frequency and the L-C-lamp initially set in the circuit is exceeded. In this situation, the energy supplied to the high-side transistor 51 is transmitted to the low-side transistor 52 without being consumed, so that the transistor may be broken.

  Therefore, in one embodiment of the present invention, the induction lamp is turned off by using the technique capable of simultaneously controlling both the frequency and the pulse width of the half-bridge circuit disclosed in Korean Patent No. 10-0825378. In the off section, the low output is maintained.

  According to an embodiment of the present invention, the duty ratio of the high-side transistor is reduced to 40% or less, while the low-side transistor is set to have a duty ratio of 60% or more in the low interval via the high-side transistor. The supplied energy can be greatly reduced. In this case, the frequency is increased by about 50%, but since the frequency is not greatly deviated from the resonance point, the circuit can operate very stably in the low section.

  Further, as shown in FIG. 5, in the decreasing section B in which the duty ratio changes from the high section A to the low section C and the rising section D in which the duty ratio changes from the low section C to the high section A, the duty ratio, that is, frequency and switching By smoothly changing the gain, the operation of the circuit can be maintained more stably. As a result, dimming of the induction lamp that has been limited to presentation can be put into practical use. The slope time is set in advance so that the rise and fall change smoothly and the frequency and gain change simultaneously. The duty ratio is changed stepwise, that is, gradually and smoothly according to the ramp time so that the circuit can operate stably.

  As described above, in one embodiment of the present invention, in order to generate and maintain a low output state, it is higher than the first resonance frequency (for example, 200 KHz), but does not impose a heavy burden on the resonance circuit 60. The frequency of the switching signal is increased to a second resonance frequency at which resonance is possible (for example, 300 KHz). More specifically, the resonance circuit 60 is designed to resonate at both the first resonance frequency and the second resonance frequency. In the off section, the frequency of the switching signal is increased to the second resonance frequency (for example, 300 KHz). At the same time, the switching gain of the high-side transistor 51 of the half-bridge circuit 50 is controlled to be a second switching gain that is reduced from a first switching gain to a duty ratio of 20% from the first switching gain. Instead, the switching gain of the low-side transistor 52 is controlled to be the third switching gain increased from the first switching gain to the duty ratio of 80% from the first switching gain.

  From the above, the induction lamp 70 is turned off without turning off the resonant circuit 60 by increasing the frequency so that the resonant circuit 60 maintains a low output, lowering the high side switching gain, and increasing the low side switching gain. It can be controlled to the state. In this state, the second resonance frequency, the second switching gain, and the third switching gain are not limited to the above values, and the ballast, that is, the resonance characteristics of the power supply circuit-half bridge circuit-resonance circuit-induction lamp and It may be designed according to circuit characteristics. In a ballast where the first resonance frequency is 200 KHz, the second resonance frequency changes in the range of about 250 to 350 KHz, the second switching gain changes in the range of about 40 to 5%, and the third switching gain May be changed in the range of 60 to 95%. Further, the frequency and the duty ratio may be set according to the output of the induction lamp and the circuit design.

  As described above, in one embodiment of the present invention, the high state output is maintained in the on period, and the low state output is maintained in the off period. Therefore, the section of the induction lamp 70 is divided into an on section and an off section by controlling only the output while maintaining the on state without controlling the on / off of the resonance circuit. As a result, the brightness of the guide lamp 70 can be controlled based on the length of the on section and the length of the off section, that is, the on gain.

  Hereinafter, a detailed embodiment will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a flowchart illustrating a method for controlling dimming of an induction lamp using a half bridge circuit according to an embodiment of the present invention.

  One embodiment of the present invention is a method for controlling dimming of an induction lamp, in which the output of the half-bridge circuit 50 is connected to the resonance circuit 60, and turning on or off of the induction lamp 70 causes resonance of the resonance circuit 60. In response, a method is provided in which the brightness of the induction lamp is controlled by controlling the gain of the on and off sections of the induction lamp 70 by control of the half-bridge circuit 50, the method comprising: including.

  In response to a dimming signal having a gain corresponding to the degree of luminance, a luminance gain setting for setting a length of a high section A in which the induction lamp 70 is turned on and a length of a low section B in which the induction lamp 70 is turned off Process S10.

  The high-side transistor of the half-bridge circuit 50 using the switching signal having the frequency of the first resonance frequency at which the resonance circuit 60 resonates in the high section A set in the switching gain and luminance gain setting process S10 of the first switching gain. High section control process S20 for switching 51 and low-side transistor 52;

  From the time point when the high section A ends, the frequency of the switching signal is increased from the first resonance frequency to the predetermined second resonance frequency, and at the same time, the high-side transistor 51 of the half-bridge circuit 50 is proportional to the increase in frequency. And a lower period control process in which the switching gain of the low-side transistor 52 of the half-bridge circuit 50 is increased to the predetermined third switching gain in proportion to the increase in frequency. S30.

  In the decrease interval control process S30, the frequency of the switching signal and the switching gains of the high side and low side transistors are changed to the set frequency and the set switching gain, and then the switching is performed for the length of the low interval set in the luminance gain setting process S10. The second resonance frequency in which the frequency of the signal is set is maintained, the second switching gain in which the high-side transistor 51 is set is maintained, and the third gain in which the switching gain of the low-side transistor 52 is set. A low period control process S40 for controlling to maintain the switching gain.

  From the time when the low section control process S40 ends, the switching signal frequency is lowered from the second resonance frequency to the first resonance frequency, and at the same time, the high-side transistor 51 of the half-bridge circuit 50 is proportional to the decrease in the frequency. Is increased from the second switching gain to the first switching gain, and the switching gain of the low-side transistor 52 of the half-bridge circuit 50 is increased from the third switching gain to the first switching in proportion to the increase in frequency. An ascending zone control process S50 that lowers the gain and returns to the high zone control process S20 after completing the change in frequency and switching gain.

  FIG. 5A is a diagram showing the dimming characteristics of the high / low control method in the induction lamp according to the embodiment of the present invention, and FIG. 5B is the induction according to the embodiment of the present invention. It is the table | surface which showed the operational characteristic of the ballast of each area for the light control of a lamp | ramp.

  In such an embodiment of the present invention, as shown in FIGS. 5 (a) and 5 (b), the operation of the ballast is basically a high section A in which the guide lamp is turned on, and the guide lamp is turned off. May be divided into a lower section C, a decrease section B in which the output decreases from the high section to the low section, and an increase section D in which the output increases from the low section to the high section.

  First, when receiving the dimming control signal, the control device 100 executes the luminance gain setting process S10 to convert the input power into the dimming voltage according to the dimming control signal, and based on the dimming voltage, The luminance gain, that is, the length of the high section A, that is, the on section, and the length of the low section C, that is, the off section are set.

  In the high section control process S20, that is, the process of controlling the on section where the induction lamp is turned on, the first resonance frequency (for example, 200 KHz) and the first switching gain (that is, 50% duty) at which the resonance circuit 60 resonates. The induction lamp 70 is turned on by switching the high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 using a switching signal having a ratio).

  Thereafter, when the time corresponding to the length of the high section A set in the luminance gain setting process S10 has elapsed, the decreasing section control process S30 is executed. In the decrease period B, the frequency of the switching signal increases from 200 KHz, that is, the first resonance frequency, to 300 KHz, that is, the preset second resonance frequency. In this case, the frequency does not increase immediately from 200 KHz to 300 KHz, but gradually increases. Similarly, by changing the pulse width from the first switching gain, ie, the duty ratio of 50%, to the second switching gain, ie, the duty ratio of 20%, the switching gain of the high-side transistor 51 is lowered. Further, the switching gain of the low-side transistor 52 is increased by changing the pulse width from the first switching gain, that is, the duty ratio of 50%, to the third switching gain, that is, the duty ratio of 80%. In this case, the frequency and switching gain can be controlled so that the change times are the same.

  As described above, in the decrease period control process S30, the output is low because the frequency is high, the switching gain of the high side transistor is low, and the switching gain of the low side transistor is high.

  When the change of the frequency and the switching gain is completed in the decrease interval control process S30, the low output is maintained in the decrease interval control process S30 for the time corresponding to the length of the decrease interval set in the luminance gain setting process S10. When the low output, that is, the frequency is controlled to be 300 KHz, the duty ratio of the high side transistor is controlled to 20%, and the duty ratio of the low side transistor 52 is controlled to be 80%, the resonance circuit Although 60 resonates, the output of the induction lamp 70 becomes weak, so it is turned off. Therefore, the OFF state is maintained during the low period C.

  When the time corresponding to the length of the lowering section set in the lowering section control process S30 has elapsed, the rising section control process S50 is executed.

  Similar to the decrease interval control process S30, the increase interval control process S50 enters the high interval A, that is, the ON interval by gradually increasing the luminance so that the output gradually increases variably. In the rising section control process S50, the switching frequency is changed from the second resonance frequency (that is, 300 KHz) to the first resonance frequency (that is, 200 KHz), that is, the switching frequency of the high section. Further, the switching gain of the high-side transistor 51 increases from a duty ratio of 20%, that is, the second switching gain, to a duty ratio of 50%, that is, the first switching gain. Further, the switching gain of the low-side transistor 52 changes from a duty ratio of 80%, that is, the third switching gain, to a duty ratio of 50%, that is, the first switching gain.

  When the switching frequency becomes the first resonance frequency (that is, 200 KHz) and the switching gain of both the high-side transistor 51 and the low-side transistor 52 becomes the same duty ratio of 50%, the high interval control process S20 is entered. This is maintained during the high period A.

  As described above, in the embodiment of the present invention, since the output is controlled not by the on / off method when performing burst dimming but by the high / low method, the operation of the circuit is artificially completely stopped. There is no. Therefore, since the load applied to the ballast is small in the process from the low period to the high period, the circuit can operate stably. For this reason, the dimming range is much wider, and the dimming control can be performed completely regardless of the severe conditions and the wattage of the induction lamp. In the low section, the current supplied from the ballast to the induction lamp is small, but the induction lamp itself maintains an off state in which the luminance is off.

  As described above, since the method of controlling the dimming of the induction lamp is controlled not by the on / off method but by the high / low method, the dimming control can be performed without turning on / off the resonance circuit. Therefore, the load applied to the circuit can be reduced, and the luminance can be controlled efficiently.

  Furthermore, in one embodiment of the present invention, for stable operation in the low period, the duty ratio of the high side transistor is controlled to be 40% or less, and the duty ratio of the low side transistor is set to 60% or more. Be controlled. Therefore, in the low section, the low output is maintained through the resonance circuit, and the induction lamp is maintained in the off state.

  Furthermore, in an embodiment of the present invention, the frequency and duty ratio are smooth so that the circuit operates more stably when the frequency and switching gain change from a high period to a low period or from a low period to a high period. The change enables stable dimming control.

  Although the invention has been described with reference to specific exemplary embodiments, the invention is not limited to these embodiments, but is limited only by the scope of the appended claims. Of course, those skilled in the art can alter or improve these embodiments without departing from the scope and spirit of the invention.

10: Bridge diode 20: DC stabilization unit 30: PFC circuit 40: DC power supply unit 50: Half bridge circuit 51: High side transistor 52: Low side transistor 60: Resonant circuit 70: Induction lamp 80: Protection circuit 90: Frequency / Pulse width control half-bridge drive unit 100: control device

Claims (4)

A method for controlling dimming of an induction lamp using a half-bridge circuit,
In response to a dimming signal, the induction section is controlled by controlling gains in the on section and the off section while repeatedly controlling an on section in which the guide lamp is turned on and an off section in which the guide lamp is turned off. Including controlling the lamp brightness;
In the ON section, the induction lamp 70 controls the high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 based on the first switching gain at a predetermined first resonance frequency. Turned on,
In the off period, the half bridge is based on a second switching gain preset lower than the first switching gain at a second resonant frequency preset higher than the first resonant frequency. At the same time as controlling the high-side transistor 51 of the circuit 50, the low-side transistor 52 is controlled based on a preset third switching gain higher than the first switching gain, thereby controlling the off period. The induction lamp has a low output state in which the induction lamp can be turned off while maintaining the resonance of the resonance circuit 60 without completely turning off the output of the half bridge circuit 50 in the off section where the induction lamp is turned off. 70 is added to the ballast in the process from the low section to the high section To reduce the load, method.   When the on-section changes to the off-section or when the off-section changes to the on-section, the switching frequency and switching gain of the high-side transistor and the low-side transistor gradually change during a predetermined slope time. The method of claim 1, controlled as follows: In this method, the dimming of the induction lamp is controlled using a half-bridge circuit. The output of the half-bridge circuit 50 is connected to the resonance circuit 60, and the on / off of the induction lamp 70 responds to the resonance of the resonance circuit 60. The brightness of the induction lamp is controlled by controlling the gain of the on and off periods of the induction lamp 70 by the control of the half-bridge circuit 50,
In response to a dimming signal having a gain corresponding to the degree of brightness, the brightness for setting the length of the high section A in which the induction lamp 70 is turned on and the length of the low section B in which the guide lamp 70 is turned off A gain setting process S10;
The half-bridge circuit 50 using a switching signal having a frequency of a first resonance frequency at which the resonance circuit 60 resonates in the high section A set in the switching gain of the first switching gain and the luminance gain setting process S10. A high section control process S20 for switching the high-side transistor 51 and the low-side transistor 52,
From the time when the high section A ends, the frequency of the switching signal is increased from the first resonance frequency to a predetermined second resonance frequency, and at the same time, the half bridge circuit 50 is proportional to the increase in the frequency. The switching gain of the high-side transistor 51 is reduced to a predetermined second switching gain, and the switching gain of the low-side transistor 52 of the half-bridge circuit 50 is increased to a predetermined third proportional to the increase in the frequency. A decrease interval control process S30 for increasing the switching gain;
The low period set in the luminance gain setting process S10 after changing the frequency of the switching signal and the switching gain of the high-side and low-side transistors to the set frequency and the set switching gain in the decrease section control process S30 The switching signal frequency maintains the set second resonance frequency, and the switching gain of the high side transistor 51 maintains the set second switching gain, and the low side A low interval control process S40 for controlling the switching gain of the transistor 52 to maintain the set third switching gain;
From the time when the low section control process S40 ends, the frequency of the switching signal is lowered from the second resonance frequency to the first resonance frequency, and at the same time, the half bridge is proportional to the decrease in the frequency. The switching gain of the high-side transistor 51 of the circuit 50 is increased from the second switching gain to the first switching gain, and the low-side transistor 52 of the half-bridge circuit 50 is proportional to the increase in the frequency. A rising interval control process S50 that lowers the switching gain of the third switching gain from the third switching gain to the first switching gain and returns to the high interval control process S20 after completion of the change of the frequency and the switching gain;
The method of claim 1 comprising: A bridge diode 10 configured to receive AC power through a fuse and a line filter and convert the AC power into DC power;
A DC stabilization unit 20 configured to stabilize the DC power of the bridge diode 10 using a reactor L, a diode D, and a capacitor C;
A power factor correction (PFC) circuit 30 configured to compensate for the power factor of the DC stabilization unit 20;
A DC power unit 40 configured to stabilize the DC output of the bridge diode 10 to 5V DC power and to output the 5V DC power;
The DC power of the DC stabilization unit 20 is received, the received DC power is switched through a serial connection between the high-side transistor 51 and the low-side transistor 52, and the switched DC power is output. A half-bridge circuit 50 configured as follows:
A resonance circuit 60 configured to receive the output of the half-bridge circuit 50 and resonate the received output via a resonance coil L and a resonance capacitor C to turn on an induction lamp;
A dimming signal is received, and based on the dimming voltage, a gain in a high section in which the induction lamp is turned on and a gain in a low section in which the induction lamp is turned off are set, and the gain in the high section and the low section is set. A control device 100 configured to set a switching frequency of the half-bridge circuit 50 and switching gains of the high-side transistor 51 and the low-side transistor 52 and generate a control signal;
The high-side transistor 51 and the low-side transistor 52 of the half-bridge circuit 50 are controlled by the control device 100, set the switching frequency as a first set frequency, and based on the first switching gain in the high section. The switching frequency is set as a second setting frequency, and the high-side transistor 51 of the half-bridge circuit 50 is controlled based on the second switching gain set lower than the first switching gain. A frequency / pulse width control half-bridge drive unit configured to control and control the low-side transistor 52 based on a third switching gain set higher than the first switching gain in the low period 90, equipped with a, induction The induction lamp 70 is set so as to have a low output state in which the induction lamp can be turned off while maintaining the resonance of the resonance circuit 60 without completely turning off the output of the half bridge circuit 50 in the off section where the conduction lamp is turned off. A dimming ballast for the induction lamp that controls and reduces the load applied to the ballast in the process from the low section to the high section .

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