JP2007103097A - Discharge lamp lighting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of improving efficiency by reducing power loss in components and facilitating countermeasures against problems such as striation and cataphoresis of a discharge lamp; and to provide a lighting system. <P>SOLUTION: This discharge lamp lighting device is provided with: a high-frequency inverter circuit 2 for alternately on/off-controlling FETs 3 and 4 for conversion to a high-frequency voltage; a resonant load circuit supplied with the high-frequency voltage from the inverter circuit and equipped with an inductor 6, a capacitor 8 and a discharge lamp 7; and a CPU 13 for continuously generating pulse voltages for on/off-driving the MOS type FETs 3 and 4 at a cycle shorter than the lighting cycle of the discharge lamp 7 based on program data and data stored in a memory 18 and for subjecting the on-width of the pulse voltages to pulse width modulation control in response to waveform variation of a sinusoidal wave voltage corresponding to the lighting cycle. In the discharge lamp lighting device, a current in the form of nearly sinusoidal waves is supplied to the discharge lamp 7 by the high-frequency output from the inverter circuit 2; and the frequency of the pulse voltage is regulated to a specific relationship of a lighting frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device and a lighting device for lighting a discharge lamp at high frequency.

  Conventionally, as an example of a discharge lamp lighting device, a pair of switch elements are connected in series to a DC power supply, and a resonant load circuit including an inductor, a capacitor, and a discharge lamp is connected in parallel to one switch element, and each switch A device that converts a DC voltage into a high-frequency voltage and supplies it to a discharge lamp by a switching operation of the device is known in which power loss of a switch device and an inductor is reduced to improve power conversion efficiency (for example, a patent) Reference 1).

In addition, the ON width of the pulse voltage for turning on / off the switching element is pulse width modulated in accordance with the change in the waveform of the sine wave voltage corresponding to the lighting cycle, so that a substantially sinusoidal current is supplied from the inverter circuit to the discharge lamp. The applicant previously filed an application that reduced reactive power and improved power conversion efficiency (Patent Document 2).
JP-A-10-243661 Japanese Patent Application No. 2004-85638

  However, in Patent Document 1 which aims to improve the power conversion efficiency by reducing the power loss of the switch element and the inductor, there is a problem that the control becomes complicated. In addition, the current limiting action of the inductor may be reduced, and the discharge lamp may not be stably maintained.

  It is an object of the present invention to provide a discharge lamp lighting device and a lighting device that can reduce reactive power and improve power conversion efficiency.

  It is another object of the present invention to provide a discharge lamp lighting device and a lighting device that can improve efficiency by reducing power loss in components.

  It is another object of the present invention to provide a discharge lamp lighting device and a lighting device that can easily take measures against the problems of discharge lamp striation and catalysis.

  The discharge lamp lighting device according to claim 1, wherein the switching element is turned on / off to convert the DC power supply voltage into a high frequency voltage; the high frequency voltage is supplied from the inverter circuit, the inductor, the capacitor, and a predetermined lighting frequency A resonant load circuit including a discharge lamp that is turned on at a time; a pulse voltage for continuously turning on and off the switch element in a cycle shorter than a discharge lamp lighting cycle; A control circuit that performs pulse width modulation according to a change in waveform of a sine wave voltage corresponding to a lighting cycle, and performs control to supply a substantially sinusoidal current from the inverter circuit to the discharge lamp, and the control circuit includes: When the lighting cycle is fs, the frequency fc of the pulse voltage is in the range of 1.5 fs to 2.5 fs.

  In this way, the ON width of the pulse voltage for driving the switch element ON / OFF is subjected to pulse width modulation according to the change in the waveform of the sine wave voltage corresponding to the lighting cycle, so that a substantially sinusoidal current flows from the inverter circuit to the discharge lamp Therefore, it is possible to reduce reactive power and improve power conversion efficiency.

  Further, since the relationship between the lighting cycle fs and the frequency fc of the pulse voltage is set to 1.5 fs ≦ fc ≦ 2.5 fs, the efficiency is improved by reducing the sum of power loss in the switching element and the inductor.

  In the present invention and the following invention, the discharge lamp lighting device detects a lamp current flowing through the discharge lamp, and a lighting cycle used for pulse width modulation of the ON width according to the detected lamp current amount. By variably controlling the amplitude of the sine wave voltage waveform corresponding to the above so that the lamp current becomes constant, the inductor can be made small and the discharge lamp can be stably lit and maintained.

  In addition, the lamp current flowing through the discharge lamp is detected, and the frequency of the sine wave voltage waveform corresponding to the lighting cycle used for pulse width modulation of the ON width is constant according to the detected lamp current amount. Thus, the inductor can be made smaller and the discharge lamp can be stably lit and maintained.

  Furthermore, the output voltage Vs in the frequency fs component when the lighting frequency of the discharge lamp is fs and the output voltage Vc in the frequency fc component when the frequency of the pulse voltage is fc (> fs) are Vs> Vc. By setting as described above, the output voltage supplied to the discharge lamp can be varied by varying the sine wave voltage of the inverter circuit, and the control width of the output voltage can be sufficiently secured.

Further, in this case, in the impedance of the resonant load circuit when the discharge lamp is rated, the power generated in the inductor component is set by setting the declination with respect to the discharge frequency fs of the discharge lamp between −20 deg to 40 deg. The circuit loss of the resonant load circuit can be reduced.

  Further, the effective value VLrms of the lighting frequency fs component of the discharge lamp included in the load voltage generated in the resonant load circuit when the discharge lamp is rated and the lighting frequency of the discharge lamp included in the output voltage of the inverter circuit By setting the DC power supply voltage so that the effective value Virms of the fs component becomes substantially equal, the power generated in the inductor component can be reduced and the circuit loss of the resonant load circuit can be reduced.

  Further, by setting the modulation factor of pulse width modulation to 0.8 or more, circuit loss can be reduced and a substantially sinusoidal output can be obtained.

  According to a second aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the control circuit performs pulse width modulation of a pulse voltage by comparing a triangular wave voltage waveform with a sine wave voltage waveform. The phase difference θ between the voltage and the sine wave voltage is (2n + 1) π / 4 ± π / 8 (n is an integer of 0 or more).

  By defining the phase difference θ within the above range, the direct current component included in the lamp current of the discharge lamp is reduced, thereby eliminating or reducing the problem of catalysis.

  According to a third aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the control circuit performs pulse width modulation of a pulse voltage by comparing a triangular wave voltage waveform with a sine wave voltage waveform. The phase difference θ between the voltage and the sine wave voltage is nπ / 2 ≦ θ ≦ (n + 1) π / 2, and the average value of the pulse voltages in the period of nπ / 2 ≦ θ <(2n + 1) π / 4, 2n + 1) π / 4 <θ ≦ (n + 1) π / 2, wherein the phase difference is periodically changed so that the sum of the average value of the pulse voltages in the period in the range of 0/2 is approximately zero. To do. (N is an integer)

  Note that the period is preferably less than 10 msec from the viewpoint of reducing visual flicker.

  In the present invention, by appropriately changing the phase difference within the above phase difference, the lamp current includes an appropriate direct current component, thereby eliminating or reducing the moving fringe phenomenon referred to as discharge lamp striation. To do.

  Further, by periodically changing, the positive and negative direct current components are canceled within one cycle, and the problem of catalysis is solved or reduced.

  The invention of claim 4 is an illumination comprising the discharge lamp lighting device according to any one of claims 1 to 3 and a lighting fixture body provided with a discharge lamp to be lit by the discharge lamp lighting device. Device.

  According to the first to third aspects of the present invention, reactive power can be reduced and power conversion efficiency can be improved, and power loss can be reduced to improve efficiency, striation, and catalysis easily. An electric lighting device can be provided.

  According to the fourth aspect of the present invention, the reactive power can be reduced, the power conversion efficiency can be improved, and the power loss can be reduced to improve the efficiency, striation, and catalysis, and reduce the problem. Can provide.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

  As shown in FIG. 1, a high frequency inverter circuit 2 is connected to a DC power source 1. In the high-frequency inverter circuit 2, a series circuit of a pair of MOS type FETs 3 and 4 is connected to the DC power source 1 as a switching element, and the drain terminal of the FET 4 is a first capacitor 5 for DC cut, a current limiting function. A resonance inductor 6 is connected in series to one end of one filament electrode 7a of the discharge lamp 7, and a source terminal is connected to one end of the other filament electrode 7b of the discharge lamp 7. A second capacitor 8 is connected between the other ends of the filament electrodes 7a and 7b of the discharge lamp 7 for flowing a resonance and preheating current.

  The inductor 6, the discharge lamp 7 and the second capacitor 8 constitute a resonant load circuit including an LC series resonant circuit. Diodes 9 and 10 are connected in parallel to the MOS FETs 3 and 4, respectively.

  Drive circuits 11 and 12 are connected to the gates of the MOS type FETs 3 and 4, and the drive circuits 11 and 12 are driven and controlled by signals from the CPU 13 constituting the control circuit. The drive circuit 11 is composed of a pair of MOS type FETs 14 and 15, and the drive circuit 12 is composed of a pair of MOS type FETs 16 and 17, which amplify signals from the CPU 13 respectively to each of the MOS type FETs 3 and 4. An on / off drive signal is supplied to the gates of the first and second gates.

  The CPU 13 has a built-in timer, and controls the timing of signals supplied to the drive circuits 11 and 12 based on a sequence program and data stored in the memory 18. That is, when the start operation is started, the CPU 13 first preheats the discharge lamp 7 for a certain period of time, then applies a high voltage for starting for a certain period of time, and performs a lighting maintenance control after the lamp is lit. It has become.

  The CPU 13 sets the operating frequency to a high reference frequency during the preheating period, and outputs a signal to the drive circuits 11 and 12 based on the reference frequency. The FETs 3 and 4 are switched and driven alternately.

  Then, when preheating for a certain time is completed, a start voltage application period starts, and the operating frequency is lowered to switch to the reference frequency at the start. At this time, the operating frequency is lowered step by step in a short time of the order of milliseconds, and is gradually lowered to shift to the reference frequency at the start. The change period to be gradually reduced is set to about 10 msec, for example. During this starting period, a starting high voltage is applied to the discharge lamp 7.

  When the discharge lamp 7 starts lighting after a certain time has elapsed, the lighting maintenance control period starts, and the operating frequency further decreases to become the reference frequency for lighting. At this time, the operating frequency is lowered step by step without being rapidly lowered in a short time of the order of nsec and shifted to the reference frequency at the time of lighting.

  In the control period in which the discharge lamp 7 is kept lit, the CPU 13 assumes that the lighting cycle (1 / lighting frequency) when the discharge lamp 7 is lit at high frequency by the high frequency voltage from the high frequency inverter circuit 2 is T. One cycle of T is divided into 10 as an example of n division, a pulse voltage for turning on and off the MOS type FETs 3 and 4 is generated in each section, and the ON width of this pulse voltage is a sine wave corresponding to the lighting cycle T Change according to voltage waveform change. That is, the pulse width modulation is performed so that the ON width changes from medium → large → medium → small → medium → large. Then, the CPU 13 supplies the pulse-width-modulated signal to the drive circuit 11, and supplies the drive signal shown in FIG. Further, the CPU 13 supplies a signal that is completely opposite to the signal supplied to the drive circuit 11 to the drive circuit 12, and supplies a drive signal from the drive circuit 12 to the MOSFET 4 so as to be turned on / off.

  In the lighting maintenance control period, the CPU 13 turns on and off the pair of MOS FETs 3 and 4 of the inverter circuit 2 at such timing, so that the gap between both ends of the MOS FET 4 of the inverter circuit 2 is shown in FIG. Such a pulse voltage is generated, and this pulse voltage waveform is supplied to a resonant load circuit including the first capacitor 5, the inductor 6, the discharge lamp 7, and the second capacitor 8. In the resonant load circuit, the harmonic component is removed by the filter effect of the inductor 6 and the capacitor 8, and the voltage waveform applied to the discharge lamp 7 becomes a substantially sinusoidal voltage waveform as shown in FIG. As a result, a substantially sinusoidal current flows through the discharge lamp 7.

  Thus, in the lighting maintenance control after the discharge lamp 7 is lit, the lighting cycle T of the discharge lamp 7 is divided into ten, and the pulse voltage for driving the MOS type FETs 3 and 4 to be turned on and off in each of the divided sections. By generating the pulse width and modulating the pulse width so that the ON width of the pulse voltage changes from medium to large to medium to small to medium to large in accordance with the waveform change of the sine wave voltage corresponding to the lighting cycle T, the inverter Since a substantially sinusoidal current can be supplied from the circuit 2 to the discharge lamp 7, reactive power can be reduced. Thereby, the improvement of power conversion efficiency can be aimed at.

  In addition, after setting the operating frequency to a high reference frequency for the discharge lamp 7 and preheating for a certain period of time, the operating frequency is lowered to the reference frequency at the start, and the starting voltage is applied. Since the frequency is gradually lowered to shift to the reference frequency at the start, circuit stress at the time of the shift can be reduced, and there is no possibility that the circuit element is destroyed at the start. Also, when the discharge lamp 7 is lit from the start-up, the reference frequency is also reduced. At this time, the reference frequency is lowered step by step to shift to the reference frequency for maintaining lighting, so that the circuit stress can be reduced.

(Second Embodiment)

  In addition, the same code | symbol is attached | subjected to the part same as embodiment mentioned above, and detailed description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 5, a hard circuit is used in place of the CPU, and the MOS FETs 3 and 4 of the inverter circuit 2 are turned on and off. That is, a sine wave voltage source 21 that generates a sine wave voltage having a frequency fL, and a triangular wave signal source 22 that generates a triangular wave signal having a frequency that is an integral multiple of the sine wave voltage frequency fL generated from the sine wave voltage source 21, for example, twice. The sine wave voltage from the sine wave voltage source 21 and the triangular wave signal from the triangular wave signal source 22 are compared. When the sine wave voltage is higher than the triangular wave signal voltage, a high level signal is output, and when the sine wave voltage is lower than the triangular wave signal voltage. A comparator 23 for outputting a low level signal is provided, and the output signal of the comparator 23 is supplied to the drive circuit 11 and also supplied to the drive circuit 12 via the inversion circuit 24. The frequency fL of the sine wave voltage generated from the sine wave voltage source 21 corresponds to the lighting cycle of the discharge lamp 7, that is, the lighting frequency.

  In such a configuration, a sine wave voltage as shown in FIG. 6A is generated from the sine wave voltage source 21, and a triangular wave voltage as shown in FIG. When this occurs, for example, one cycle of the lighting cycle is divided into two, and a pulse voltage as shown in FIG. In addition to being supplied to the drive circuit 12 via the inversion circuit 24.

  The pulse voltage in each section varies between the high level and the low level according to the average value of the sine wave voltage in the section. The smaller the average value, the longer the period during which the low level is output, and the larger the average value. The period during which high level is output becomes longer. In this way, pulse width modulation is performed according to the average value in the section of the sine wave voltage.

  The drive circuit 11 drives the MOS FET 3 on and off with a drive signal having the same waveform as that shown in FIG. 6B, and the drive circuit 12 uses the drive signal having a waveform obtained by inverting the waveform shown in FIG. Drive on and off.

  As a result, during the lighting maintenance control period, a pulse voltage as shown in FIG. 3 (with a different number of divisions) is generated between both ends of the MOS type FET 4 of the inverter circuit 2 as in the first embodiment described above. The harmonic component of the pulse voltage is removed by the filter effect of the inductor 6 and the capacitor 8. Thus, a substantially sinusoidal voltage waveform as shown in FIG. 4 is applied to the discharge lamp 7. As a result, a substantially sinusoidal current flows through the discharge lamp 7. Therefore, also in this embodiment, the effect that the reactive power can be reduced and the power conversion efficiency can be improved is obtained.

(Third embodiment)

  Here, the relationship between fs and fc when the lighting frequency (1 / T) of the discharge lamp 7 is fs, and the frequency of the pulse voltage for turning on and off the MOS type FETs 3 and 4 is fc, and the relative ratio among the components. In particular, attention was paid to the relationship between the power loss of the MOS type FETs 3 and 4 and the inductor 6 having a large power loss, and the experiment was confirmed. The result is shown in FIG.

  FIG. 7 shows the logarithm of frequency on the horizontal axis and the power loss on the vertical axis. The MOS FETs 3 and 4 in the case where the lighting frequency fs is fixed at 20 KHz and the frequency fc of the pulse voltage is changed are shown. It shows the change state of the loss (switching loss), the loss of the inductor 6 (the loss of the winding Lr) and the sum of the losses.

  As shown in FIG. 7, the sum of losses showed the minimum value when the frequency fc of the pulse voltage was 40 KHz, and the loss was relatively reduced if it was between 30 KHz and 50 KHz (1.5 fs to 2.5 fs). It turns out that it can be reduced. This tendency was the same even when the experiment was performed with the lighting frequency fs fixed at a different frequency.

  Therefore, it is effective to set the frequency fc of the pulse voltage within the range of 1.5 fs to 2.5 fs from the viewpoint of reducing the power loss of the component parts.

  Further, FIG. 8 shows the result of the experiment focusing on the relationship between the phase difference between the sine wave voltage and the triangular wave voltage and the direct current component (DC) included in the lamp current supplied to the discharge lamp 7. In FIG. 8, the horizontal axis represents the phase difference θ, and the vertical axis represents the direct current component (DC) included in the lamp current. The direct current component (DC) is shown as a relative value when the voltage applied to both ends of the FET 4 (FIG. 3) is 1. Actually, although the direct current component (DC) is generated in positive and negative directions according to the phase difference, the absolute value is displayed. That is, in FIG. 8, π / 4 or less is positive, but π / 4 to 3π / 4 is negative, and 3π / 4 or more exhibits positive periodic fluctuation.

  In FIG. 8, curves fc and fs respectively represent the frequency component and the lighting frequency component of the pulse voltage in the lamp current as relative values.

  As is apparent from FIG. 8, in order to reduce the direct current component (DC) and reduce the cataphoresis problem of the discharge lamp 7, the phase difference θ is set to (2n + 1) π / 4 ± π / 8 (n is an integer of 0 or more). ) Is effective.

  On the other hand, when priority is given to countermeasures against striation problems, it is effective to include a direct current component (DC) in the lamp current, so the phase difference θ is set to a value other than (2n + 1) π / 4 (n is an integer). Should.

  Further, the phase difference θ is set to nπ / 2 ≦ θ ≦ (n + 1) π / 2, and the average value of the pulse voltage in the range of nπ / 2 ≦ θ <(2n + 1) π / 4, and (2n + 1) π / 4 If the phase difference is periodically changed so that the sum of the average value of the pulse voltages in the range of <θ ≦ (n + 1) π / 2 (n is an integer) is substantially 0, a moderate direct current is applied to the lamp current. It is possible to eliminate or reduce the moving fringe phenomenon called discharge lamp striation by adding components, and by changing periodically, the positive and negative DC components are canceled within one cycle, and cataphoresis This problem can be solved or reduced.

(Third embodiment)

  In this embodiment, for example, in the second embodiment described above, that is, in FIG. 5, the lighting frequency of the discharge lamp 7 is fs, and the frequency of the pulse voltage output from the comparator 23 is fc (> fs). In the output voltage frequency characteristics of the resonant load circuit using the rated load, the output voltage Vs in the frequency fs component and the output voltage Vc in the frequency fc component are set to satisfy Vs> Vc.

  By making such a setting, the output voltage supplied to the discharge lamp 7 as a load can be varied by changing the sine wave voltage from the sine wave voltage source 21, and the control range of the output voltage is sufficient. Can be secured.

  For example, as shown in FIG. 9, the amplitude of the triangular wave signal S1 from the triangular wave signal source 22 is 1, the amplitude of the sine wave signal S2 from the sine wave voltage source 21 is 0.8, and the lighting frequency fs of the discharge lamp 7 is set. When the frequency fc of the pulse voltage output from the comparator 23 is 50 MHz and the frequency fc is 1 MHz, the comparator 23 outputs “1” when the voltage of the sine wave signal S2 is larger than the voltage of the triangular wave signal S1, and the voltage of the sine wave signal S2. 10 is equal to or lower than the voltage of the triangular wave signal S1, the output is set to “0”. Therefore, the pulse width-modulated pulse voltage waveform output from the comparator 23 is as shown in FIG.

  By the way, the effective values of the frequency fs component and the frequency fc component included in the pulse voltage waveform output from the comparator 23 are shown with respect to the amplitude of the sine wave signal S2 when the amplitude of the triangular wave signal S1 is "1". As shown in FIG. In FIG. 11, a graph g1 shows an effective value of the frequency fs component, a graph g2 shows an effective value of the frequency fc component, and a graph g3 shows a value obtained by adding the effective value of the frequency fs component and the effective value of the frequency fc component. Yes.

  From the graph of FIG. 11, for example, when the amplitude of the sine wave signal S2 is 0.6, the effective value of the frequency fs component is approximately 0.4, and the effective value of the frequency fc component is approximately 0.7. When the amplitude of the signal S2 is 0.8, the effective value of the frequency fs component and the effective value of the frequency fc component are both approximately 0.6, and when the amplitude of the sine wave signal S2 is 1.0, the effective frequency fs component is effective. It can be seen that the value is approximately 0.7 and the effective value of the frequency fc component is reversed to approximately 0.4. It can also be seen that the sum of the effective value of the frequency fs component and the effective value of the frequency fc component is constant at approximately 1.13 when the amplitude of the sine wave signal S2 is 0.4 or more.

  The pulse voltage from the comparator 23 is supplied to the drive circuit 11 to switch drive the MOS FET 3 of the inverter circuit 2, and this pulse voltage is inverted by the inverter circuit 24 and supplied to the drive circuit 12 to supply the MOS of the inverter circuit 2. When the type FET 4 is switched and driven, the inverter circuit 2 generates a pulse-width-modulated output voltage shown in FIG. 12, and a resonant load circuit including the first capacitor 5, the inductor 6, the discharge lamp 7, and the second capacitor 8. To be supplied. At this time, the output according to the frequency characteristic of the resonant load circuit is supplied to the discharge lamp 7 which is a load.

  That is, for each frequency component included in the pulse width modulated output voltage output from the inverter circuit 2, an output according to the gain of the resonant load circuit is obtained for each frequency component. Becomes the final output and is supplied to the discharge lamp 7.

  In order for the final output supplied to the discharge lamp 7 to have a substantially sinusoidal output, it is necessary to attenuate the harmonic component including the frequency fc component using the frequency characteristic of the resonant load circuit. Further, it can be seen from the graph shown in FIG. 11 that when the effective value of the frequency fs component is increased, the effective value of the frequency fc component is decreased. For example, when the amplitude of the sine wave signal S2 is 0.6, the effective value of the frequency fs component is approximately 0.4 and the effective value of the frequency fc component is approximately 0.7. In this case, FIG. When power of each frequency is supplied from the power supply AC to the equivalent circuit of the resonant load circuit, the characteristic indicated by the solid line graph in FIG. 14 is obtained as the output voltage generated across the resistor R.

  In the equivalent circuit of FIG. 13, Lr represents an inductor component, Cf represents a capacitor component, and R represents an equivalent load resistance during rated operation of the discharge lamp 7.

  The resonance frequency (1 / 2π√Lr · Cf) of the resonance load circuit is set to be higher than the frequency fs and lower than the frequency fc.

  A solid line graph g11 in FIG. 14 shows a case where the effective value of AC is about 0.4, and a solid line graph g12 shows a case where the effective value of AC is about 0.7. This corresponds to the case where the amplitude of the sine wave signal S2 is 0.6.

  From FIG. 11, when the amplitude of the sine wave signal S2 is 0.6, the effective value of the frequency fs component is approximately 0.4, the effective value of the frequency fc component is approximately 0.7, and the sum of the effective values is It is almost constant. When the amplitude of the sine wave signal S2 is changed to 0.8 and 1.0, the effective value of the frequency fs component increases and the effective value of the frequency fc component decreases, but the sum of the effective values is substantially constant. It does not change.

  This indicates that the same applies to the pulse width modulated output voltage output from the inverter circuit 2 when the inverter circuit 2 is driven by the pulse voltage from the comparator 23. That is, when the amplitude of the sine wave signal S2 is changed from 0.6 to 1.0, the effective value of the frequency fs component and the effective value of the frequency fc component change in the output voltage from the inverter circuit 2, respectively. The sum of the effective values becomes substantially constant.

  Further, in FIG. 14, the result of examining the relationship between the output voltage Vs at the frequency fs when the effective value of AC is approximately 0.4 and the output voltage Vc1 at the frequency fc when the effective value of AC is approximately 0.7. When Lr and Cr are set so that both are substantially equal, the effective value of the output voltage hardly changes even if the amplitude of the sine wave is changed from 0.4 to 1.0.

  In other words, in the relationship in which the output voltage at the frequency fs and the output voltage at the frequency fc are substantially equal, even if the amplitude of the sine wave signal S2 is changed from 0.2 to 1.0, for example, it is supplied to the discharge lamp 7. It was found that the final output hardly changed as shown by the graph g3 in FIG.

  Therefore, the present inventor considers that the output voltage Vs at the frequency fs is different from the output voltage Vc at the frequency fc, and changes the inductor component Lr and the capacitor component Cf or changes the frequency fc from the characteristics shown in FIG. Therefore, Vs> Vc can be set, and an experiment was conducted on this.

  The inductor component Lr and the capacitor component Cf are set so that the output voltage is greatly reduced near the frequency fc, and the output voltage characteristics appearing across the resistor R are measured. When the effective value of AC is approximately 0.4, 14 shows a characteristic indicated by a dotted line graph g21. When the effective value of AC is approximately 0.7, a characteristic indicated by a dotted line graph g22 is obtained in FIG. From this characteristic, the relationship between the output voltage Vs at the frequency fs when the effective value of AC is approximately 0.4 and the output voltage Vc2 at the frequency fc when the effective value of AC is approximately 0.7 is Vs>. It became Vc2.

  Under these conditions, when the amplitude of the sine wave signal S2 is changed from 0.2 to 1.0, the final output supplied to the discharge lamp 7 changes as shown by a graph g4 in FIG. It was. That is, when the lighting frequency of the discharge lamp 7 is fs and the frequency of the pulse voltage output from the comparator 23 is fc (> fs), the output of the resonant load circuit using the equivalent load resistance at the rated operation of the discharge lamp 7 In the frequency characteristics of the voltage, if the output voltage Vs in the frequency fs component and the output voltage Vc in the frequency fc component are set to satisfy Vs> Vc, the amplitude of the sine wave voltage from the sine wave voltage source 21 is changed. Thus, the output voltage supplied to the discharge lamp 7 can be varied, and a sufficient control width of the output voltage can be secured.

  As a result, the discharge lamp 7 can be dimmed and controlled by changing the amplitude of the sine wave voltage from the sine wave voltage source 21. Further, it is possible to easily control the output so as to meet the rating of the discharge lamp 7 to be lit.

  It can be seen from the solid line graph g12 in FIG. 14 that the output voltage Vc1 at the frequency fc decreases as the frequency fc is increased. Therefore, in order to vary the output voltage supplied to the discharge lamp 7 by changing the amplitude of the sine wave voltage from the sine wave voltage source 21, the frequency fc is increased without changing the inductor component Lr and the capacitor component Cf. May be.

  In addition, although this embodiment described what was applied to 2nd Embodiment, it is not limited to this, For example, it can apply also to 1st Embodiment or another embodiment. is there. Or a combination is possible between each embodiment.

(Fourth embodiment)

  In this embodiment, when the lighting frequency of the discharge lamp 7 is fs and the frequency of the pulse voltage output from the comparator 23 is fc (> fs), the resonance using the equivalent load resistance at the rated operation of the discharge lamp 7 is used. In the frequency characteristic of the output voltage of the load circuit, in the fifth embodiment in which the output voltage Vs in the frequency fs component and the output voltage Vc in the frequency fc component are set to satisfy Vs> Vc, the rated load is further set. The condition is that the declination of the impedance of the used resonant load circuit with respect to the lighting frequency fs of the discharge lamp 7 is set between -20 deg and 40 deg.

  That is, there are an infinite number of combinations of the inductor component Lr and the capacitor component Cf for supplying desired electric power to the discharge lamp 7 with respect to the DC voltage VDC supplied to the inverter circuit 2. For this reason, it is difficult to simply specify the combination of the inductor component Lr and the capacitor component Cf to reduce the reactive power and reduce the circuit loss.

13, the impedance Z of the resonant load circuit as seen from the power source AC is Re (Z) + j · Im (Z) = jωLr + 1 / ((1 / R) + jωCf, which is a vector. 16, the angle formed by the impedance Z and the real part Re (Z) is a declination, that is, declination = tan ⁻¹ (Im (Z) / Re (Z)).

  If the declination is reduced from the vector of FIG. 16, the imaginary part can be reduced. This will reduce reactive power. Therefore, in the resonant load circuit, in order to reduce the reactive power and reduce the circuit loss, it can be defined by the deflection angle of the impedance Z of the resonant load circuit.

  For example, when the DC voltage VDC = 350 V, the lighting frequency fs = 20 kHz, the pulse voltage frequency fc = 200 kHz, the equivalent resistance at the rated operation of the discharge lamp 7 is 300Ω, and the rated current of the discharge lamp 7 is 0.37 A. When the deflection angle was changed to -40 deg, -20 deg, 0 deg, 20 deg, 40 deg, 60 deg and the power VA generated in the inductor component Lr at that time was plotted, the result shown in FIG. 17 was obtained.

  From the results of FIG. 17, if the declination is set in the range of −20 deg to 40 deg, the power VA generated in the inductor component Lr can be reduced, and the reactive power can be reduced. In particular, at 0 deg to 20 deg, the power VA generated in the inductor component Lr can be sufficiently reduced, and the reactive power can be greatly reduced.

  On the other hand, when the declination is less than −20 deg, the electric power VA generated in the inductor component Lr increases rapidly. Further, when the declination exceeds 40 deg, the power VA generated in the inductor component Lr increases rapidly. Therefore, a range where the declination is less than −20 deg or a range where the declination exceeds 40 deg is not preferable because reactive power increases and circuit loss increases.

  Thus, by setting the declination in the range of −20 deg to 40 deg, the power VA generated in the inductor component Lr can be reduced, and the circuit loss in the resonant load circuit can be reduced. And since the electric power VA which generate | occur | produces in the inductor component Lr can be made small, the inductor 6 to be used can also be reduced in size.

(Fifth embodiment)

  In this embodiment, when the lighting frequency of the discharge lamp 7 is fs and the frequency of the pulse voltage output from the comparator 23 is fc (> fs), the resonance using the equivalent load resistance at the rated operation of the discharge lamp 7 is used. In the frequency characteristics of the output voltage of the load circuit, the output voltage Vs in the frequency fs component and the output voltage Vc in the frequency fc component are set so that Vs> Vc, and further, the impedance of the resonant load circuit using the rated load In the sixth embodiment in which the deviation angle of the discharge lamp 7 with respect to the lighting frequency fs is set between −10 deg and 40 deg, the discharge voltage included in the load voltage generated in the resonant load circuit using the rated load is further included. The effective value VLrms of the lighting frequency fs component of the lamp 7 and the effective value Virms of the lighting frequency fs component of the discharge lamp 7 included in the output voltage of the inverter circuit 2 are substantially equal. As, in which the condition to set a DC power supply voltage VDC from the DC power source 1 to be applied to the inverter circuit 2.

  In the discharge lamp lighting device having the circuit configuration shown in FIG. 5, for example, the lighting frequency fs = 20 kHz of the discharge lamp 7, the pulse voltage frequency fc = 200 kHz, and the sine wave voltage source 21 for the triangular wave signal from the triangular wave signal source 22 are generated. The modulation factor of the sine wave voltage is 0.9, the rated current of the discharge lamp 7 is 0.37 A, the lamp voltage is 113 V, and the first capacitor 5, the inductor 6, the discharge lamp with respect to the DC power supply voltage VDC from the DC power supply 1. When the impedance deviation angle of the resonant load circuit composed of 7 and the second capacitor 8 is set to 0 deg and the DC power supply voltage VDC is used as a parameter, the power VA generated in the inductor component Lr with respect to each DC power supply voltage VDC is obtained. The result shown in 18 was obtained.

  The graph of FIG. 18 shows that the power VA generated in the inductor component Lr decreases as the DC power supply voltage VDC increases, and that the inductor 6 to be used can be reduced in size as the DC power supply voltage VDC increases. ing.

  The output voltage supplied from the inverter circuit 2 to the resonant load circuit is a pulse width modulation waveform, which includes a frequency component of a sine wave voltage and a frequency component of a pulse voltage. Since the triangular wave signal with amplitude 1 is modulated with a sine wave voltage with amplitude 0.9, the degree of modulation of the output voltage from the inverter circuit 2 is also 0.9. That is, the output voltage from the inverter circuit 2 has a voltage waveform as shown in FIG.

  The modulation signal component included here can be expressed as: Virms = VDC / (2√2) · α. Here, Virms is an effective value of the lighting frequency fs component of the discharge lamp 7 included in the output voltage of the inverter circuit 2, and α is a modulation degree.

  By setting the effective value Virms to be substantially equal to the effective value VLrms of the lighting frequency fs component of the discharge lamp 7 included in the load voltage generated in the resonant load circuit using the rated load, the DC power supply voltage VDC is It becomes possible to set high. That is, since the effective value VLrms corresponds to the lamp voltage, in the above example, VLrms = 113V. Since α = 0.9, the DC power supply voltage VDC is 355 V from the above equation. This voltage value is a substantially upper limit value of the DC power supply voltage VDC that can be set. If the DC power supply voltage VDC is higher than 355V, it becomes impossible to set the necessary inductor component Lr and capacitor component Cf.

  In this way, the DC power supply voltage VDC can be set high, whereby the power VA generated in the inductor component Lr can be reduced and the circuit loss in the resonant load circuit can be reduced. In addition, since the electric power VA generated in the inductor component Lr can be reduced, the inductor 6 to be used can also be reduced in size.

(Sixth embodiment)

  This embodiment describes the lighting fixture provided with the discharge lamp lighting device of each embodiment mentioned above.

  FIG. 20 shows a luminaire 100. The luminaire 100 has a discharge lamp 103 attached to a socket 102 of a luminaire main body 101, and the discharge lamp lighting device according to any one of the above-described embodiments is disposed inside. 104, and the discharge lamp 103 is lit by the discharge lamp lighting device 104.

  Thus, the lighting fixture provided with the discharge lamp lighting device of each embodiment mentioned above is realizable. That is, the lighting fixture which can aim at the improvement of power conversion efficiency is realizable. Further, when a discharge lamp lighting device that performs feedback control is used, it is possible to realize a lighting fixture that can stably keep the discharge lamp lit even if the inductor 6 is made smaller.

  In addition, when a discharge lamp lighting device in which the output voltage Vs in the frequency fs component and the output voltage Vc in the frequency fc component are set to satisfy Vs> Vc is used, the illumination that can sufficiently secure the control range of the output voltage An instrument can be realized. Further, by setting the declination angle of the impedance of the resonant load circuit with respect to the discharge frequency fs of the discharge lamp to be between -10 deg to 40 deg, the discharge lamp lighting frequency fs included in the load voltage generated in the resonant load circuit. By setting the DC power supply voltage so that the effective value VLrms of the component and the effective value Virms of the lighting frequency fs component of the discharge lamp included in the output voltage of the inverter circuit 2 are substantially equal, the circuit loss can be reduced, and the inductor A luminaire that can be miniaturized can be realized.

The circuit block diagram containing the one part block which shows 1st Embodiment of this invention. The figure which shows the drive signal waveform which carries out the on-off drive of MOSFET in the embodiment. The figure which shows the voltage waveform which generate | occur | produces between the both ends of MOSFET of the inverter circuit in the embodiment. The figure which shows the voltage waveform applied to the discharge lamp in the embodiment. The circuit block diagram which shows the 2nd Embodiment of this invention. Diagram showing sine wave voltage, triangular voltage pulse voltage Diagram showing the relationship between the same frequency and power loss Diagram showing the relationship between phase difference and DC component Waveform diagram showing the amplitude of triangular and sine wave signals Diagram showing pulse width modulated pulse voltage waveform output from comparator The graph which shows the effective value of the frequency fs component contained in the pulse voltage waveform output from a comparator, and the frequency fc component, and the effective value of the sum Diagram showing output voltage waveform of inverter circuit Circuit diagram showing equivalent circuit of resonant load circuit The figure which shows the output voltage characteristic which generate | occur | produces between resistance both ends at the time of supplying the electric power of each frequency from a power supply with respect to an equivalent circuit, changing an effective value Graph showing the final output supplied to the discharge lamp when the amplitude of the sine wave signal is changed with Vs = Vc and Vs> Vc Diagram for explaining the deflection angle of a resonant load circuit A graph showing the relationship between the deflection angle and the electric power VA generated in the inductor component Lr The graph which shows electric power VA which generate | occur | produces in the inductor component Lr with respect to DC power supply voltage VDC when the impedance deflection angle of a resonant load circuit is set to 0deg Diagram showing output voltage waveform of inverter circuit Perspective view of lighting device

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... High frequency inverter circuit, 3, 4 ... MOS type FET, 6 ... Inductor, 7 ... Discharge lamp, 8 ... 2nd capacitor, 13 ... CPU, 18 ... Memory, 21 ... Sine wave voltage source, 22 ... Triangular wave signal source, 23 ... Comparator.

Claims (4)

An inverter circuit that controls on and off of the switch element to convert a DC power supply voltage into a high-frequency voltage;
A resonant load circuit including a discharge lamp that is supplied with a high-frequency voltage from an inverter circuit and is lit at a predetermined lighting frequency;
A pulse voltage for continuously turning on and off the switch element is generated at a cycle shorter than the lighting cycle of the discharge lamp, and the ON width of the pulse voltage is changed according to the waveform change of the sine wave voltage corresponding to the lighting cycle. A control circuit that performs pulse width modulation and performs control for supplying a substantially sinusoidal current from the inverter circuit to the discharge lamp;
When the lighting cycle is fs, the control circuit sets the frequency fc of the pulse voltage to a range of 1.5 fs to 2.5 fs.   The control circuit performs pulse width modulation of a pulse voltage by comparing a triangular wave voltage waveform and a sine wave voltage waveform, and sets a phase difference θ between the triangular wave voltage and the sine wave voltage to (2n + 1) π / 4 ± π. 2. The discharge lamp lighting device according to claim 1, wherein n is an integer of 0 or more. The control circuit performs pulse width modulation of a pulse voltage by comparing a triangular wave voltage waveform and a sine wave voltage waveform, and sets a phase difference θ between the triangular wave voltage and the sine wave voltage to nπ / 2 ≦ θ ≦ (n + 1). ) Π / 2,
The average value of the pulse voltage in the range of nπ / 2 ≦ θ <(2n + 1) π / 4, and the average value of the pulse voltage in the range of (2n + 1) π / 4 <θ ≦ (n + 1) π / 2 The discharge lamp lighting device according to claim 1, wherein the phase difference is periodically changed so that the sum of the two becomes substantially zero. (N is an integer) A lighting fixture body;
The discharge lamp lighting device according to any one of claims 1 to 3, wherein a discharge lamp disposed in the luminaire body is over-stored;
An illumination device comprising:

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