JPH10243661A - Power supply, discharge lamp lighting device and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency by utilizing a switching element of low dielectric strength and small capacity and by reducing power loss through reduction of a DC voltage to be applied to an inverter apparatus. SOLUTION: An impedance phase angle arg(Z) of a load circuit is set at 0 deg.<=arg(Z)<=40 deg. and a DC voltage VDC of a DC power supply apparatus 1 and a load voltage VL of regular operation of load 6 are set to have the relationship of 1.2VL<=VDC<=2.0VL. Thereby, the efficiency can be improved by reduction an inductance 7 of load circuit and power loss in the switching devices 3, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply having an inverter for converting a DC voltage to a high-frequency voltage, a discharge lamp lighting device and a lighting device using the power supply.

[0002]

2. Description of the Related Art Conventionally, many types of such devices have been proposed. As one of the prior arts, a power supply device and a discharge lamp lighting device using a so-called series inverter in which a pair of switching devices are connected in series with each other are known.

[0003] This prior art includes a load such as a discharge lamp,
A load circuit including an LC series resonance circuit including an inductor and a capacitor, wherein a switching output by the pair of switching devices is supplied to the load circuit.

Further, in order to respond to recent demands for reducing input current distortion, an active filter comprising a boosting chopper is provided on the input side of an inverter device.

In such prior art, the input voltage value to the inverter device, that is, the output voltage value of the active filter is set relatively high so that a high voltage for starting the discharge lamp can be easily obtained. Further, the relationship between the AC power supply voltage value and the control IC of the active filter also affects the setting of the input voltage value to the inverter device. That is, it is recommended that the boosting ratio be 130% or more as a control IC for a commercially available active filter. Therefore, in the case of an AC voltage having an effective value of 100 V, the inverter input voltage, that is, the output voltage of the active filter is 11
0 V (considering 10% voltage fluctuation) × 1.4 × 1.3 = 2
The usual design concept was to make it larger than 00.2V.

[0006] Further, it has been a usual design idea to always increase the switching frequency of the pair of switching devices with respect to the resonance frequency of the inductor and the capacitor of the load circuit. The reason for this is that if the switching frequency is set lower than the resonance frequency, the switching device enters the fast switching mode and a large reactive current flows in the reverse direction when the switching device is turned on.

[0007]

In the prior art, the input voltage to the inverter device is set relatively high in consideration of the ease of starting the discharge lamp and the control IC of the active filter. Therefore, it is necessary to use a switching element having a relatively high withstand voltage and a large capacity in the switching device, and there is a problem that the switching device becomes expensive. In addition, the prior art is not designed from the viewpoint of improving the efficiency of the entire device in consideration of the power loss, so that there is room for improving the efficiency.

The present invention provides a power supply device, a discharge lamp lighting device, and a lighting device capable of reducing the input voltage to an inverter device to use a switching element having a low withstand voltage and a small capacity and reducing power loss to improve efficiency. It is intended to provide a device.

[0009]

According to a first aspect of the present invention, there is provided a power supply apparatus comprising: a DC power supply; a pair of switching devices connected in series with each other; a load and an LC series resonance circuit; An inverter device that converts a DC voltage from a DC power supply into a high-frequency voltage and supplies the high-frequency voltage to a load; and an impedance phase angle arg of the load circuit as viewed from the switching device. Z) is 0 ° ≦ arg (Z) ≦ 4
0 °, and the DC voltage VDC and the load voltage (effective value) VL during steady operation of the load are 1.2 VL ≦ VDC ≦
It is characterized in that the relationship is set to 2.0 VL.

The inventors of the present application have made various studies on the relationship between the DC voltage value supplied to the inverter device, the impedance phase angle of the load circuit, and the power loss, and have assumed the following assumption. That is, the switching loss in the switching device having a large specific gravity in the inverter device and the power loss in the inductor can be reduced by reducing the impedance phase angle of the load circuit. At the same time, by setting the DC voltage to the inverter device within a predetermined range, power loss in the switching device and the inductor can be reduced.

Hereinafter, the result of simulation based on these assumptions will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a basic configuration of a discharge lamp lighting device according to the present invention, FIG. 2 is a diagram showing a relationship between a DC voltage and power loss of an inductor, and FIG. 3 is a relationship between a DC voltage and switching loss of a switching device. FIG. 4 is a diagram showing the relationship between the DC voltage and the sum of the power loss of the inductor and the switching device. FIG. 5 is an equivalent circuit diagram of the load circuit. FIG. 6 is a diagram showing the impedance phase angle of the load circuit. 7 is a current waveform diagram of the switching device according to the present invention, and FIG. 8 is a current waveform diagram of the conventional switching device.

In FIG. 1, reference numeral 1 denotes a DC power supply,
2 is an inverter device. The inverter device 2 has a pair of switching devices 3 and 4 connected in series to each other. The load circuit 5 includes an LC series resonance circuit including a discharge lamp 6, an inductor 7, and a capacitor 8. Reference numeral 9 denotes a DC cut capacitor. In such a discharge lamp lighting device, the pair of switching devices 3 and 4 are alternately turned on and off to supply a high frequency voltage to the discharge lamp 6. 1, the inductor 7
Also functions as a current limiting element of the discharge lamp 6.

In this configuration, the inventors of the present application firstly
The relationship between the DC voltage VDC and the power loss of the inductor 7 when the impedance phase angle arg (Z) of the load circuit 5 was changed was calculated. Here, the impedance phase angle arg (Z) of the load circuit 5 is represented as shown in FIG. That is, the equivalent circuit of the load circuit 5 can be represented as shown in FIG. 5, and the impedance Z is Z = jωL + {1 / (1 / R + jωC)} = ZR + j (XL−XC).

R: resistance value of load 6, L: inductance value of inductor 7, C: capacitance value of capacitor 8,
ZR = R / (1 + ω2C2R2), XL = ωL, XC = 1 /
{Ω (1 + ω2C2R2) / ω2CR2)}.

As the discharge lamp 6, a fluorescent lamp FLR40S / M / 36 manufactured by Toshiba Lighting & Technology Corp. is turned on. A lamp power of 30.72 W is obtained, and a lamp voltage of about 1 is obtained.
00V.

FIG. 2 shows the calculation results. As is clear from FIG. 2, the smaller the phase angle arg (Z), the smaller the power loss in the inductor 7. Phase angle arg (Z) =
At 0 ° the power loss is minimized. Although the loss in the inductor 7 is determined by K1 (constant) × current value × current value × ωL, it is clear from FIG. 6 that the L value relatively increases as the phase angle arg (Z) increases. is there. Note that it is possible to further reduce the L value by setting the phase angle arg (Z) <0 °, but in this case, it is excluded because it is in the advanced switching mode.

Next, the present inventors calculated the relationship between the DC voltage VDC and the switching loss of the switching devices 3 and 4 when the impedance phase angle arg (Z) of the load circuit 5 was changed. FIG. 3 shows the calculation results. FIG. 3 also shows that the smaller the phase angle arg (Z) is, the smaller the switching loss in the switching devices 3 and 4 is, and the smaller the phase angle arg (Z) is, the smaller the power loss is. That is, the phase angle arg (Z)
As it approaches = 0 °, the phase difference between the current and the voltage of the switching device approaches zero, thus reducing the switching loss.

FIG. 4 shows the relationship between the DC voltage and the sum of the power loss of the inductor 7 and the switching devices 3 and 4. FIG. 4 shows a case where the phase angle arg (Z) = 0 °. From FIG. 4, it can be seen that the DC voltage VDC is 120 V ≦ VDC ≦ 200.
If V, power loss is 0.125W or less, 140V ≦ V
It can be seen that the power loss can be minimized if DC ≦ 180 V and the power loss can be minimized if the DC voltage VDC = 160 V or less.

If the value of the DC voltage VDC is expressed in relation to the rated lamp voltage VL of the discharge lamp 6, then 1.2 VL ≦ V
DC ≦ 2.0 VL, 1.4 VL ≦ VDC ≦ 1.8 VL, and DC voltage VDC = 1.6 VL. This relationship is the same for other discharge lamps. Also, the phase angle arg (Z)
The same tendency is exhibited even when the phase angle is changed, and the phase angle arg (Z)
If 0 ° ≦ arg (Z) ≦ 40 °, the power loss could be reduced as compared with the conventional case.

The current waveforms of the switching devices 3 and 4 at this time are as shown in FIG. That is, during the ON period Ton of the switching device 3 (4), the switching device 3 (4)
Is cut off before reaching zero after passing the peak value. In other words, the relationship between the time Tpeak until the peak value is reached and the on-time Ton is 0 ≦ Tpeak ≦ Ton
/ 2 relationship. The current waveform of the switching device 3 (4) has the above relationship, and the phase angle arg (Z)
If 0 ° ≦ arg (Z) ≦ 40 °, the inductor 7
In addition, the sum of the power loss of the switching devices 3 and 4 can be reduced as compared with the related art as described above. The setting of the current waveform and the phase angle arg (Z) of the switching device as described above depends on the DC voltage VDC, the switching frequency, and the inductor 7.
It can be easily implemented by those skilled in the art by selecting the inductance value and the capacitance value of the capacitor 8.

The current waveform of the conventional switching device is as shown in FIG. 8, and the switching device is cut off when the resonance current substantially reaches a peak value. Further, according to the conventional design concept (in which the DC voltage is relatively large and the inductance L value is large so that the switching mode always becomes the slow mode), the phase angle arg (Z) is substantially the same for the same load. 50 ° to 60 °, and the power loss was about 0.6 W.

Therefore, in the first aspect of the present invention, it is specified that the phase angle arg (Z) is 0 ° ≦ arg (Z) ≦ 40 ° and the input voltage VDC is 2VL ≦ VDC ≦ 2.0VL.

In the first aspect and the following invention, the DC power supply may have any configuration unless otherwise specified. For example, an active filter including a step-up chopper, a series dropper, a smoothing capacitor, or the like can be used. Further, the DC power supply device is a device that supplies a DC voltage as viewed from the inverter device, and it does not matter whether it is a single device or a plurality. As a load, a discharge lamp is typically used.
Any type such as a welding machine and a motor may be used. Furthermore, it may be a DC load. In the case of a DC load, a rectifier may be provided at the input stage of the load. In addition, the load is 1
One or a plurality of them may be provided in series or in parallel. When provided in series, the total load voltage corresponds to the load voltage of the present invention. Furthermore, the switching device may be any device such as a bipolar transistor or a field effect transistor. However, from the viewpoint that switching loss can be reduced, a device having a small on-resistance and a high switching speed is preferable. Further, in the present application, “serial” and “parallel” mean that not only a case in which they are in direct series or a direct parallel relationship with each other but also a case in which another component is interposed.

According to a second aspect of the present invention, there is provided a power supply apparatus comprising: a DC power supply; a pair of switching devices connected in series to each other; a load; a series resonance circuit of an inductor and a capacitor; An inverter device that converts a DC voltage from the DC power supply device to a high-frequency voltage and supplies the high-frequency voltage to a load, so that the sum of switching loss in the switching device and power loss in the inductor is close to a minimum value. The DC voltage value, the switching frequency, the inductance value of the inductor, and the capacitance value of the capacitor are set, and the impedance phase angle arg (Z) of the load circuit viewed from the switching device is 0 ° ≦ arg (Z) ≦ 40.
°.

In the present invention, the expression that the sum of the switching loss and the power loss in the inductor is near the minimum value includes the minimum value and means a range of the minimum value × 1.1. The DC voltage value,
It is easy for those skilled in the art to select the switching frequency, the inductance value of the inductor, and the capacitance value of the capacitor. For example, it may be set as in claim 1.

According to a third aspect of the present invention, there is provided a power supply device comprising: a DC power supply device; a pair of switching devices connected in series with each other; and a load circuit including a load and an LC series resonance circuit and supplied with a switching output of the switching device. Has,
An inverter device for converting a DC voltage from a DC power supply into a high-frequency voltage and supplying the high-frequency voltage to a load, wherein each of the switching devices is turned off before a resonance current flowing through the switching device has reached a peak value and reaches zero. And turned on and off alternately.

According to a fourth aspect of the present invention, there is provided a power supply device comprising: a DC power supply device; a pair of switching devices connected in series with each other; and a load circuit including a load and an LC series resonance circuit and supplied with a switching output of the switching device. Has,
An inverter device that converts a DC voltage from a DC power supply device to a high-frequency voltage and supplies the high-frequency voltage to a load; and wherein each of the switching devices has a time until a resonance current flowing through the switching device reaches a peak value during an on-time. Is Tpeak and the on-time is Ton, the circuit is turned on and off alternately so as to satisfy the relationship of 0 ≦ Tpeak ≦ Ton / 2.

According to a fifth aspect of the present invention, there is provided the power supply device according to any one of the first to fourth aspects, wherein the DC voltage VDC and the load voltage VL during a steady operation of the load are 1.4 VL ≦ VDC ≦ 1.
8 VL.

According to the fifth aspect of the present invention, as described above, the power loss can be further reduced.

According to a sixth aspect of the present invention, in the power supply device according to any one of the first to fifth aspects, the DC voltage VDC is approximately 1.
6 VL.

According to the invention of claim 6, the power loss can be reduced most.

In the present invention, approximately 1.6 VL means ± 1.
This means allowing a range of 0%. A power supply device according to claim 7, a DC power supply device; a pair of switching devices connected in series to each other; a transformer having an input winding connected to one of the pair of switching devices in parallel;
An inverter device having a load connected to the output winding of the transformer and a load circuit including an LC series resonance circuit, and converting the DC voltage from the DC power supply into a high-frequency voltage and supplying the high-frequency voltage to the load; The impedance phase angle arg (Z) of the load circuit viewed from the transformer is 0 ° ≦ arg (Z)
≦ 40 ° and the voltage V of the output winding of the transformer
S (peak-peak) and a load voltage (effective value) VL at the time of steady operation of the load are set in a relationship of 1.2 VL ≦ VS ≦ 2.0 VL.

According to the present invention, as shown in FIG. 9, a transformer 10 is used for step-up, step-down, insulation, or the like in the relationship between the load voltage VL and the DC voltage VDC during the steady operation of the load 6. It was done about the case. The impedance phase angle arg (Z) of the load circuit 5
Is defined for the same reason as the first aspect of the present invention. Regarding the relationship between the voltage VS of the output winding of the transformer 10 and the load voltage (effective value) VL during the steady operation of the load 6, when attention is paid to the power loss in the inductor 7, the voltage VS of the output winding of the transformer 10 2. The DC voltage V according to claim 1, wherein the magnitude of (peak-peak) is
Since it corresponds to the magnitude of DC, it is defined for the same reason.

In the present invention, the transformer 10 has an insulation type,
Any of single winding type may be used. Further, the DC cut capacitor 9 may be connected in series with the input winding of the transformer 10.

In the power supply device according to the present invention, the voltage VS of the output winding and the load voltage VL at the time of steady operation of the load are set in a relationship of 1.4 VL ≦ VS ≦ 1.8 VL. It is characterized by having done.

According to a ninth aspect of the present invention, in the power supply device according to the seventh or eighth aspect, the voltage VS of the output winding is set to approximately 1.
It is characterized in that it is set to 6 VL.

[0038] The power supply device according to claim 10 is characterized in that
In any one of 2, 5 to 9, the impedance phase angle arg (Z) of the load circuit is set to 0 ° ≦ ar
g (Z) ≦ 24 °.

According to the present invention, the impedance phase angle a
Since rg (Z) is defined in a range closer to 0 °, the power loss can be further reduced.

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the DC power supply device includes a rectifying device for rectifying an AC voltage; DC conversion means for outputting to the apparatus; and wherein the relationship between the output voltage VDC and the AC voltage (effective value) VIN of the DC conversion means is VDC ≧ 1.80 VIN.

The present invention considers the case where an active filter composed of a step-up chopper is used as the DC converting means. To stably control the active filter, the step-up ratio is set to 1.3 times the peak value of the AC voltage. It is known and recommended to do so. Therefore, VDC ≧ 1.8
If it is 0VIN, 1.80 / 21/2 becomes about 1.28, which can be approached to 1.3.

According to the present invention, an active filter can be used, and distortion of an input current from an AC power supply can be reduced. Further, the active filter can be controlled stably.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects of the present invention, the inverter device includes a pair of inverters at a frequency lower than a resonance frequency of the LC series resonance circuit when the load is in a steady operation. The switching device switches the switching device.

According to the present invention, the switching frequency during the steady operation of the load is made lower than the resonance frequency of the LC series resonance circuit. This means that the impedance phase angle ar of the load circuit is
In relation to g (Z), the phase angle arg (Z) is 0 °.
, Which means that the inductance L value can be reduced. Therefore, it contributes to a reduction in power loss.

FIG. 10 is a diagram showing the frequency characteristics of the load circuit of the present invention, and FIG. 11 is a diagram showing the frequency characteristics of the conventional load circuit. In FIGS. 10 and 11, a indicates no load, b indicates a steady load, and c indicates a switching frequency at a steady load. Conventionally, a load circuit and a switching frequency are generally set so as to have a relationship shown in FIG. On the other hand, according to the present invention, the setting is performed as shown in FIG.

It should be noted that the resonance frequency of the entire load circuit including the load is set to a switching frequency such that the switching mode is the slow switching mode. It is preferable that the switching frequency be higher than the resonance frequency of the LC series resonance circuit before the load starts.

According to a thirteenth aspect of the present invention, in the power supply device according to any one of the first to twelfth aspects, the load current value when the load is in a steady operation is detected, and the load current value is set to a predetermined value. And a control means for controlling the DC power supply device so as to obtain a value.

The present invention controls the output voltage of the DC power supply even when the load current changes due to load fluctuation, power supply fluctuation, and the like. Therefore, a constant current of the load can be achieved.

According to a fourteenth aspect of the present invention, there is provided the discharge lamp lighting device according to any one of the first to thirteenth aspects, wherein the load is a discharge lamp, and the load voltage VL during a steady operation is a rated lamp voltage. Features. The discharge lamp may be any type such as a hot cathode type, a cold cathode type, a high-intensity discharge lamp, and the like.

According to a fifteenth aspect of the present invention, there is provided the discharge lamp lighting device according to the fourteenth aspect, wherein the output voltage of the DC power supply is stabilized by a detection signal corresponding to the output voltage value of the DC power supply before the discharge lamp is lit. And controlling means for controlling the DC power supply so that the lamp current is stabilized by a signal corresponding to the lamp current value after the discharge lamp is turned on.

According to the present invention, since the output voltage of the DC power supply is fixed before the discharge lamp is started, the output of the DC power supply does not become excessive. Further, since the lamp current becomes constant after the discharge lamp is turned on, the discharge lamp can be stably turned on even when the output characteristic of the inverter device has a constant voltage characteristic as described later.

When the discharge lamp is of a hot cathode type, it is preferable to change the switching frequency of the inverter device in accordance with the preheating of the filament and the application of the starting voltage. That is, at the time of filament preheating, the switching frequency is set to a voltage value that is suitable for filament preheating but does not lead to starting. Next, when a starting voltage is applied, the switching frequency is set to a voltage value at which the discharge lamp can be started.

According to a sixteenth aspect of the present invention, there is provided the discharge lamp lighting device according to the fifteenth aspect, wherein the detection signal corresponding to the output voltage value of the DC power supply device and the signal corresponding to the lamp current value have a high value priority. The discharge lamps are connected in parallel with each other, and the sum of signals corresponding to the lamp currents of the discharge lamps is compared with a detection signal corresponding to the output voltage value of the DC power supply. In addition, the discharge lamp is set to be larger than the detection signal corresponding to the output voltage value of the DC power supply device when all the discharge lamps are turned on at the rated speed.

According to the present invention, since all of the plurality of discharge lamps connected in parallel are turned on, the DC power supply is controlled by a signal corresponding to the lamp current. I do.

A lighting device according to claim 17, a lighting fixture body; a discharge lamp provided in the lighting fixture body; and a discharge lamp lighting device according to any one of claims 14 to 16, for lighting the discharge lamp; It is characterized by having.

The present invention is a lighting device having the same function as the discharge lamp lighting device according to any one of claims 14 to 16.

[0057]

Next, a first embodiment of the present invention will be described.

FIG. 12 is a circuit diagram of the first embodiment of the present invention. 81 is an AC power supply, for example, a 50 Hz, 100 V commercial power supply. Reference numeral 82 denotes a DC power supply device that inputs an AC voltage from the AC power supply 81 via a high-frequency blocking filter 83 and outputs a smoothed DC voltage. In this embodiment, a pair of diodes 84 and 85 connected to both output terminals of a filter 83, and a pair of switching elements 86 and 87 provided in parallel with the diodes 84 and 85 are provided.
Having. The middle of the pair of diodes 84 and 85 and the middle of the pair of switching elements 86 and 87 are connected. Further, inductors 88 and 89 are provided between respective cathodes of the pair of diodes 84 and 85 and non-common connection ends of the pair of switching elements 86 and 87, respectively. Further, a smoothing capacitor 90 is connected in parallel with one switching element 86, and diodes 91 and 92 are provided between the positive terminal of the smoothing capacitor 90 and the non-common connection end of each of the switching elements 86 and 87. ing. The control means for turning on and off the pair of switching elements 86 and 87 is not shown, but can be constituted by a commercially available control IC or the like. The switching frequency is not particularly limited as long as it is more than twice the frequency of the AC power supply 81.
It is preferably between 0 KHz and 200 KHz.

The inverter device 2 has the circuit configuration shown in FIG.
It is similar to that of Although the switching control means of the inverter device 2 is not shown, the well-known control I
It can be appropriately constituted by C or the like. The switching frequency is also 20 KHz to 200 KHz as in the case of the DC power supply 82.
It is preferred that Details of each component of the present embodiment are as follows.

Load 6: Fluorescent lamp FLR40S / M / 36 manufactured by Toshiba Lighting & Technology Corp. (Rated lamp voltage 100V) Inductor 7: 0.437mH Capacitor 8: 6.86nF LC resonance frequency: 91.9KHz Impedance of load circuit 5 Phase angle arg (Z) = 0 ° Switching frequency during steady operation of load 6: 50 KHz
Constant load power: 30.72 W Next, the operation of the present embodiment will be described. DC power supply 8
2, when the output of the AC power supply 81 is positive on the diode 84 side, the AC power supply 81, the high frequency blocking filter 83, and the inductor 88 are turned on during the ON period of the switching element 86.
A current flows through the switching element 86, the diode 85, the high frequency blocking filter 83, and the AC power supply 81. Also, an AC power supply 81, a high frequency blocking filter 83, an inductor 88
A switching element 86; a parasitic diode of the switching element 87; an inductor 89;
-A current also flows through the path of the AC power supply 81. When the switching element 86 is turned off, the energy stored in the inductor 88 is discharged through the path of the inductor 88 -the diode 91 -the capacitor for smoothing 90 -the diode 84 -the inductor 88, and is added to the voltage of the AC power supply 81 so as to be added to the smoothing capacitor 90. Charge.

When the output of the AC power supply 81 is positive on the diode 85 side, during the ON period of the switching element 87, the AC power supply 81, the high frequency blocking filter 83, the inductor 89,
A current flows through the switching element 87, the diode 84, the high frequency blocking filter 83, and the AC power supply 81. Further, an AC power supply 81, a high-frequency blocking filter 83, an inductor 89,
Switching element 87-Parasitic diode of switching element 86-Inductor 88-High frequency blocking filter 83-
Current also flows through the path of the AC power supply 81. When the switching element 87 is turned off, the energy stored in the inductor 89 is discharged through the path of the inductor 89-diode 92-smoothing capacitor 90-diode 85-inductor 89, and is added to the voltage of the AC power supply 81 to be smoothed. Charge. Then, the output voltage of the DC power supply 82 was set to 180V.

Since the DC power supply 82 of the present embodiment is of a double switching element type, it requires only two input side diodes 84 and 85, and uses a full-wave rectifier as in the conventional single switching element type. Compared to
The number of diodes can be reduced. Therefore, the power loss in the diode can be reduced to about 1/2. On the other hand,
According to the present embodiment, inductors 88, 8
9 and the switching elements 86 and 87, the total power loss increases,
% Power loss can be reduced, and the efficiency of the DC power supply 82 alone can be increased to 97.6%.

In the inverter device 2, the DC voltage is supplied from the DC power supply device 82 and converted into a high frequency voltage to energize the load 6. At the time of steady operation of the load 6,
The switching frequency is 50 KHz and the load 6
When 0.72 W was supplied, the power loss in the switching devices 3 and 4 and the inductor 7 could be reduced, and the efficiency in the inverter device 2 could be increased to 98.1%. The total efficiency with the DC power supply 82 of this embodiment is 9
It was 5.3%.

Next, a second embodiment of the present invention will be described. FIG. 13 is a circuit diagram showing a second embodiment of the present invention. The same or corresponding parts as those in FIG. 1 or FIG. 12 are denoted by the same reference numerals. In the present embodiment, two loads 6, 6
For example, discharge lamps are provided in parallel with each other. The inductor 7 and the capacitor 8 also have respective loads 6, 6
It corresponds to. Reference numeral 95 denotes a control unit that controls the DC power supply so that the output voltage of the DC power supply 82 is stabilized by a detection signal corresponding to the output voltage value of the DC power supply 82 before each of the loads 6 and 6 is turned on. After the lighting of the loads 6, 6, the DC power supply 82 is controlled so that the lamp current is stabilized by a signal corresponding to the lamp current value.

The control means 95 includes a voltage detection means 96 for detecting a signal corresponding to the output voltage of the DC power supply 82, and current detection means 97 and 97 for detecting a signal corresponding to the lamp current of each of the loads 6, 6. An output control means 98 for controlling the output voltage of the DC power supply 82 according to the larger one of the signals is provided. The current detection means 97, 97 are configured to add the detection signals of each other (or to AND the two). Then, the voltage detection means 96 and the current detection means 97, 97 become larger than the detection signal of the voltage detection means 96 by each of the current detection means 97, 97 detecting a signal corresponding to the lamp current at the time of steady operation. Relationships have been made. Note that only the current detecting means 97 and 97 are omitted (the voltage detecting means 96 is omitted),
The output control means 9 is determined by the larger one of the detection signals 7 and 97.
8 may be controlled.

This embodiment has inverter control means 99. Inverter control means 99 includes load voltage detection means 100 for detecting the voltage between both ends of each of the loads 6, 6,
100, and a frequency control means 101 for controlling the switching frequency of the inverter device in accordance with the larger detection signal of the load voltage detection means 100, 100. The frequency control unit 101 has a timer (not shown) such as a timer and a time constant circuit, and the switching frequency is changed by the timer. Further, the frequency control means 101 receives the lighting signal from the current detection means 97, 97 and changes the switching frequency. Note that the frequency control means 101 may change the switching frequency with a voltage signal from the load voltage detection means 100.

Next, the operation of the present embodiment will be described. At the time of starting the loads 6, 6 at the time of turning on the power supply, the switching frequency is set so that the loads 6, 6 cannot be started until the timing means measures a predetermined time so that the output becomes suitable for filament preheating. Set to. For example, when the resonance frequency of the LC resonance circuit is 91.9 KHz, the frequency is set to 120 KHz. In this case, the output voltage of DC power supply device 82 is controlled to be constant in accordance with its own output voltage (for example, 25
0V). Then, when the timer measures a predetermined time, the switching frequency is made lower (for example, 100 KHz) than at the time of filament preheating, and a voltage capable of starting and lighting is applied to the loads 6,6. Therefore, the loads 6, 6 are turned on,
Current detecting means 97, 97 detect the lamp current. This signal is supplied to the output control means 98, and thereafter, the output voltage of the DC power supply 82 is controlled according to this signal. Load 6,
When both lights up, the load voltage detecting means 100, 10
Upon receiving the signal from 0, the frequency control means 101 further lowers the switching frequency (for example, 50 KHz). Also, the detection signal to the output control means 98 is such that the signal from the current detection means 97, 97 becomes larger than the signal from the voltage detection means 96, and thereafter, the output voltage of the DC power supply is controlled so that the lamp current becomes constant. I do. As a result, FIG.
As shown in FIG. 3, stable lighting can be achieved by increasing the intersection angle with respect to the load curves of the loads 6 and 6 exhibiting constant voltage characteristics. On the other hand, when the lamp current stabilization control is not performed as in the present embodiment, the load characteristics of the inverter device also exhibit constant voltage characteristics, and stable lighting may be difficult.

FIG. 14 is a simplified diagram showing one embodiment of a lighting device. 111 is a lighting fixture main body that supports the discharge lamp 6. Reference numeral 112 denotes a reflection pair constituting a part of the lighting fixture main body 111, and reference numeral 113 denotes a socket. Then, any of the above-described discharge lamp lighting devices of the present invention is used for lighting the discharge lamp 6. It is optional whether the discharge lamp lighting device is provided inside the lighting fixture main body 111 or outside.

[0069]

According to the first to fourth aspects of the present invention, the impedance phase angle of the load circuit, the DC voltage value input to the inverter device, and the current waveform of the switching device are specified. The efficiency can be improved by reducing the power loss of the inductor.

According to the fifth and sixth aspects of the present invention, the DC voltage value is specified to a more desirable value, and the efficiency can be further improved.

According to the seventh aspect of the present invention, a transformer is used, and the efficiency can be improved as in the first aspect of the present invention.

The inventions according to claims 8 and 9 are based on claim 7
In the invention described above, a more desirable value is specified, and the efficiency can be further improved.

According to the tenth aspect of the present invention, the impedance phase angle of the load circuit is specified to a more desirable value, and the efficiency can be further improved.

According to the eleventh aspect of the present invention, a DC power supply device such as an active filter is used as the DC power supply device, and the relationship between the AC power supply voltage and the DC voltage value is specified. And distortion of the input current from the AC power supply can be reduced.

According to the twelfth aspect of the present invention, the switching frequency during steady operation is made lower than the resonance frequency of the LC series resonance circuit in the inverter device, so that the inductance value of the LC series resonance circuit can be made small. Can also reduce the power loss.

According to the thirteenth aspect of the present invention, the DC power supply is controlled in accordance with the load current during the steady operation, so that the load current can be made constant.

The invention according to claim 14 uses a discharge lamp as a load, and can provide a highly efficient discharge lamp lighting device.

According to the fifteenth aspect of the present invention, the control method of the DC power supply before and after lighting the discharge lamp is different, so that the output of the DC power supply can be prevented from becoming excessive before lighting. After lighting, the discharge lamp can be lit stably.

According to the sixteenth aspect of the present invention, it is possible to provide a lighting device with improved efficiency as in the above invention.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a basic configuration of a discharge lamp lighting device according to the present invention.

FIG. 2 is a diagram showing a relationship between a DC voltage and a power loss of an inductor.

FIG. 3 is a diagram showing a relationship between a DC voltage and power loss of a switching device.

FIG. 4 is a diagram showing a relationship between a DC voltage and the sum of power loss of an inductor and a switching device.

FIG. 5 is an equivalent circuit diagram of a load circuit.

FIG. 6 is a diagram showing an impedance phase angle of a load circuit;

FIG. 7 is a current waveform diagram of the switching device according to the present invention.

FIG. 8 is a current waveform diagram of a conventional switching device.

FIG. 9 is a circuit diagram showing one embodiment of a discharge lamp lighting device of the present invention.

FIG. 10 is a diagram showing a frequency characteristic of the load circuit of the present invention.

FIG. 11 is a diagram showing frequency characteristics of a conventional load circuit.

FIG. 12 is a circuit diagram showing another embodiment of the discharge lamp lighting device of the present invention.

FIG. 13 is a circuit diagram showing another embodiment of the discharge lamp lighting device of the present invention.

FIG. 14 is a diagram showing load characteristics and a load curve of a discharge lamp according to the embodiment shown in FIG. 9;

FIG. 15 is a diagram showing one embodiment of a lighting device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DC power supply device 2 Inverter device 3 4 Switching device 5 Load circuit 6 Load

Claims (17)

[Claims] 1. A DC power supply, comprising: a DC power supply; a pair of switching devices connected in series to each other; and a load circuit including a load and an LC series resonance circuit and supplied with a switching output of the switching device. And an inverter device for converting a DC voltage from the switching device to a high-frequency voltage and supplying the high-frequency voltage to a load, wherein the impedance phase angle arg (Z) of the load circuit viewed from the switching device is 0 ° ≦ arg (Z) ≦ 40 °. And the DC voltage VDC and the load voltage (effective value) VL during steady operation of the load are 1.2 VL ≦ VDC ≦ 2.0
A power supply device set in a relation of VL. 2. A DC power supply, comprising: a pair of switching devices connected in series with each other; a load; a series resonance circuit of an inductor and a capacitor; An inverter device for converting a voltage into a high-frequency voltage and supplying the high-frequency voltage to a load; and a DC voltage value, a switching frequency, The inductance value of the inductor and the capacitance value of the capacitor are set, and the impedance phase angle arg (Z) of the load circuit viewed from the switching device is 0 ° ≦ arg (Z).
A power supply device characterized by ≦ 40 °. 3. A DC power supply, comprising: a DC power supply; a pair of switching devices connected in series to each other; and a load circuit including a load and an LC series resonance circuit and supplied with a switching output of the switching device. And an inverter device for converting a DC voltage from the DC voltage into a high-frequency voltage and supplying the high-frequency voltage to a load, wherein each of the switching devices is turned off before a resonance current flowing through the switching device reaches a zero after passing a peak value. A power supply device which is turned on and off alternately. 4. A DC power supply device comprising: a DC power supply device; a pair of switching devices connected in series to each other; and a load circuit including a load and an LC series resonance circuit and supplied with a switching output of the switching device. An inverter device that converts the DC voltage from the DC voltage into a high-frequency voltage and supplies the high-frequency voltage to a load, wherein each of the switching devices has a time Tpeak until a resonance current flowing through the switching device reaches a peak value during the on-time. Assuming that the ON time is Ton, 0 ≦ Tpeak ≦ Ton / 2
A power supply device which is turned on and off alternately so as to satisfy the following relationship. 5. The relationship between the DC voltage VDC and the load voltage VL during steady operation of the load is 1.4 VL ≦ VDC ≦ 1.8 V.
The power supply device according to claim 1, wherein the power supply device is L. 6. The power supply device according to claim 1, wherein said DC voltage VDC is approximately 1.6 VL. 7. A DC power supply device; a pair of switching devices connected in series to each other; a transformer having an input winding connected in parallel to one of the pair of switching devices; and a transformer connected to an output winding of the transformer. And a load circuit that includes a connected load and an LC series resonance circuit; and an inverter device that converts a DC voltage from the DC power supply device to a high-frequency voltage and supplies the high-frequency voltage to the load. The observed impedance phase angle arg (Z) of the load circuit is 0 ° ≦ arg (Z) ≦ 40 °
Wherein a voltage VS (peak-peak) of an output winding of the transformer and a load voltage (effective value) VL during a steady operation of the load are set in a relationship of 1.2 VL ≦ VS ≦ 2.0 VL. Power supply. 8. The voltage VS of the output winding of the transformer and the load voltage VL of the load during normal operation of the load are 1.4 VL.ltoreq.VS.
The power supply device according to claim 7, wherein ≤ 1.8VL. 9. The power supply according to claim 7, wherein a voltage VS of an output winding of the transformer is approximately 1.6 VL. 10. An impedance phase angle arg of a load circuit.
10. The power supply according to claim 1, wherein (Z) satisfies 0 ° ≦ arg (Z) ≦ 24 °. 11. The DC power supply device comprises: a rectifier for rectifying an AC voltage; and a DC converter for boosting and smoothing the output of the rectifier and outputting the output to the inverter. VDC and AC voltage (effective value) V
11. The power supply device according to claim 1, wherein IN is set such that VDC ≧ 1.80VIN. 12. The inverter device according to claim 1, wherein said inverter device switches a pair of switching devices at a frequency lower than a resonance frequency of an LC series resonance circuit during a steady operation of said load. A power supply according to one of the preceding claims. 13. A control means for detecting a load current value when the load is in a steady state operation and controlling a DC power supply device so that the load current value becomes a predetermined value set in advance. Item 13. The power supply device according to any one of Items 1 to 12. 14. The discharge lamp lighting device according to claim 1, wherein the load is a discharge lamp, and the load voltage VL at the time of steady operation is a rated lamp voltage. 15. A control method for controlling a DC power supply so that an output voltage of the DC power supply is stabilized by a detection signal corresponding to an output voltage value of the DC power supply before the discharge lamp is turned on, and after the discharge lamp is turned on. 15. The discharge lamp lighting device according to claim 14, further comprising control means for controlling the DC power supply so that the lamp current is stabilized by a signal corresponding to the lamp current value. 16. A detection signal corresponding to an output voltage value of the DC power supply device and a signal corresponding to the lamp current value act on control means with a high value priority, and the discharge lamps are arranged in parallel with each other. The sum of the signals corresponding to the lamp currents of the discharge lamps is compared with the detection signal corresponding to the output voltage value of the DC power supply, and the DC power supply 16. The discharge lamp lighting device according to claim 15, wherein the discharge lamp lighting device is set to be larger than a detection signal corresponding to an output voltage value of the device. 17. A lighting fixture body; a discharge lamp provided in the lighting fixture body; and lighting the discharge lamp.
And a discharge lamp lighting device according to any one of the preceding claims.