JPH05284735A - Power supply device and discharge lamp lighting device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a power supply device in which the boost chopper circuit does not cause an intermittent operation even when a light load is seen from the boost chopper circuit depending on the state of the load device. [Structure] A state of a load device 10 is detected, and when the load state viewed from the chopper circuit 20 becomes a light load, the inductance value of an inductor device 21 of a boost chopper circuit 20 is reduced. [Effect] When the load device becomes a light load as viewed from the step-up chopper circuit, the switching means detects this state and reduces the inductance value of the inductor device of the step-up chopper circuit, so that the power stored in the inductor device decreases. As a result, the charging charge of the smoothing capacitor is also reduced, and as a result, the rise of the output voltage of the boost chopper circuit is suppressed.
As a result, even if the load device has a light load to some extent, the boost chopper circuit can be prevented from operating intermittently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device using a boost chopper circuit and a discharge lamp lighting device using this power supply device.

[0002]

2. Description of the Related Art Conventionally, this type of power supply device has been constructed as shown in FIG. In FIG. 4, reference numeral 1 is a rectifying device for rectifying the output of the AC power source e, and 2 is a step-up chopper circuit for converting the output voltage of the rectifying device 1 into a desired smoothed DC voltage. The step-up type chopper circuit 2 mainly includes an inductor 3, a switching device 4 that is provided between the output ends of the rectifying device 1 in series with the inductor 3, and controls a current of the inductor 3 and a smoothing capacitor 5. It is well known. Reference numeral 6 is a diode for preventing backflow. Further, an output control device 7 that performs negative feedback control according to its own output voltage is provided, and the boost chopper circuit 2 is provided.
The output voltage is constant. The output control device 7 performs, for example, on-duty control of the switching device 4 in accordance with the output voltage, and can be configured by using a commercially available IC or the like. Reference numeral 10 is a load device to which the output of the chopper circuit 2 is supplied.

Since such a power supply device can obtain a smoothed DC voltage without distorting the input current, it has been particularly noticed recently.

[0004]

In such a power supply device, the inductance value of the inductor device 3 is set on the assumption that the load device 10 is in a predetermined state. Therefore, when the load device 10 has a lighter load than the predetermined state, the output voltage of the step-up chopper circuit 2 rises as much as the power is not consumed by the load device 10. If the voltage rises excessively, the load device 10 will be damaged and other adverse effects will occur. Therefore, the output control device 7 is provided with an overvoltage protection function. That is, when the on-duty is made extremely small, or when the on-duty becomes the set value or more, the switching device 4
Is to turn off.

However, when the overvoltage protection is performed in this way, the boost chopper circuit 2 operates intermittently, and electric power is intermittently supplied to the load device 10.
Therefore, there is a problem that the load device 10 cannot operate normally. For example, if the load device 10 includes an inverter, the inverter may oscillate abnormally. Further, for example, in the case where the electric power for the control device for the load such as the inverter is obtained from the winding magnetically coupled to the inductor device 3, there is a problem that the load cannot be stably controlled.

The present invention has been made to solve such a conventional problem, and the step-up chopper circuit causes an intermittent operation even when the load chopper circuit has a light load depending on the state of the load device. It is an object of the present invention to provide a power supply device that does not have a power supply.

The present invention also provides an inverter as a load device.
It is an object of the present invention to provide a discharge lamp lighting device that includes a battery and a discharge lamp, and in which the boost chopper circuit does not cause an intermittent operation even under a light load such as a filament preheating state.

Further, according to the present invention, the electric power for the control device of the inverter for energizing the discharge lamp is obtained from the winding magnetically coupled to the inductor device. It is an object of the present invention to provide a discharge lamp lighting device capable of stably supplying electric power for the control device without the intermittent operation of the boost chopper circuit even under a light load.

[0009]

According to a first aspect of the present invention, the state of a load device is detected, and when the load state seen from the chopper circuit becomes a light load, the inductance value of the inductor device of the step-up chopper circuit is set. It is designed to be small.

According to a second aspect of the present invention, the load device has an inverter and a discharge lamp. When the input or output current of the inverter is detected and the detected current value is smaller than a predetermined value. The inductance value of the inductor device is reduced.

According to a third aspect of the present invention, in addition to the second aspect, power for the control device of the inverter is obtained from a winding magnetically coupled to the inductor device. Is.

[0012]

According to the first aspect of the present invention, when the load device becomes a light load as viewed from the boost chopper circuit, the switching means detects this state and reduces the inductance value of the inductor device of the boost chopper circuit. As a result, the electric power accumulated in the inductor device is reduced and the electric charge charged in the smoothing capacitor is also reduced. As a result, the rise in the output voltage of the boost chopper circuit is suppressed. Therefore, even if the load device is lightly loaded to some extent, the boost chopper circuit is prevented from operating intermittently.

According to a second aspect of the present invention, the inductance value of the inductor device is reduced when the input or output current of the inverter, which is a load device, is smaller than a predetermined value. Therefore, the discharge lamp which is the load of the inverter device is reduced. Even when the filament is preheated, this is detected to reduce the inductance value of the inductor device. Thus, even under a light load such as the filament preheating state, the boost chopper circuit does not operate intermittently and the inverter does not abnormally oscillate.

According to the third aspect of the invention, since the power for the inverter control device is obtained from the winding magnetically coupled to the inductor device, the power supply for the control device can be simply constructed, and
Even when the load is light, power can be supplied stably, and inverter control can be performed stably.

In any of the inventions, when there is no load such as when the load device is removed, the on-duty of the switching device is made extremely small, or the switching device 4 is turned off when the load device exceeds a set value as in the conventional case. Over voltage protection.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the discharge lamp lighting device of the present invention will be described below with reference to FIG. The same or corresponding portions as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.
In this embodiment, the inductor device 21 of the boost chopper circuit 20 has an intermediate tap so that the inductance value can be switched. Reference numeral 25 is a switching means, and in the present embodiment, when a current detection device 26 for detecting the current of the load device 10 and a detection value of the current detection device 26 and a preset reference value are compared, The determination device 27 that outputs a signal and the determination device 2 that is provided such that the intermediate tap and one end of the inductor device 21 can be short-circuited
And a transistor 28 whose on / off is controlled by a signal from 7. Note that the boost chopper circuit 20 performs constant voltage control as in the conventional case, and thus the load power is detected by detecting the current of the load device 10.

Next, the operation of this embodiment will be described. The load device 10 is operating normally, and the boost chopper circuit 2
When it is in a predetermined load state when viewed from 0, that is, when the detected value of the current detection device 26 is larger than the predetermined value, the transistor 28 is not turned on and the inductor device 21 is set to a large inductance value.

On the other hand, when the load device 10 is lightly loaded, the detection value of the current detection device 26 becomes small, and the determination device 27 outputs a signal to turn on the transistor 28.
This reduces the inductance value and the stored power. As a result, the charging charge of the smoothing capacitor 5 also decreases, and the output voltage value of the boost chopper circuit 20 becomes smaller than that when the inductance value is not changed. Therefore, the overvoltage protection function of the output control device 7 does not operate and the boost chopper circuit 20 does not operate intermittently.

Next, an embodiment of the illuminating device of the present invention will be described with reference to FIG. The same parts as those in FIG. 1 are designated by the same reference numerals. In the present embodiment, the load device 11 is an inverter 12 as a high frequency converter, a discharge lamp 13 such as a fluorescent lamp which is energized by the output of the inverter 12, and a filament preheating for the discharge lamp 13. It is composed of a capacitor 14.

Further, in this embodiment, the switching means 35
The means for transmitting a signal from the judging device 27 'to the transistor 28 mainly comprises the light emitting means 36a and the light receiving means 36b.

Still another embodiment will be described with reference to FIG. Also in this embodiment, FIG.
The same parts as those in the figure are denoted by the same reference numerals. In the present embodiment, the inverter 12 'is a so-called separately excited type, and has a control device 15 for on / off controlling the switching elements of the inverter 12'. Then, the electric power of the control device 15 is obtained from the winding 16 magnetically coupled to the inductor device 21. That is, although detailed illustration is omitted, the output of the winding 16 is rectified,
It is input after performing necessary processing such as smoothing and constant voltage. Further, in this embodiment, the current detecting device 26 is provided so as to detect the output current of the inverter 12 '.

In the present embodiment, when the discharge lamp 14 is in the filament preheat state and in the light load state, the current detecting device 26
Becomes smaller, the determination device 27 outputs a signal to turn on the transistor 28. This reduces the inductance value and the stored power. As a result, the charging charge of the smoothing capacitor 5 also decreases, and the output voltage value of the boost chopper circuit 20 becomes smaller than that when the inductance value is not changed. Therefore, the overvoltage protection function of the output control device 7 operates and the boost chopper circuit 2
0 is not operated intermittently. As a result, the winding 16
, The voltage value of which may be lowered (as described above, a voltage-regulating means may be used if necessary) is continuously output, and the control device 15 stabilizes the inverter 1.
Control 2 '.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, the switching means may detect the current and voltage of the load device, or may detect only the voltage when the boost chopper circuit performs constant current control. In short, any device that can detect the load state of the load device may be used. Also,
The inductance value may be switched by another method such as providing an auxiliary winding and changing the excitation of the auxiliary winding.

[0024]

As described above, according to the invention described in claim 1, when the load device becomes a light load as viewed from the boost chopper circuit, the switching means detects this state and the inductance of the inductor device of the boost chopper circuit is detected. Since the value is small, the power stored in the inductor device is small,
The charging charge of the smoothing capacitor is also reduced, and as a result, the rise of the output voltage of the boost chopper circuit is suppressed. As a result, even if the load device has a light load to some extent, the boost chopper circuit can be prevented from operating intermittently.

According to a second aspect of the present invention, the inductance value of the inductor device is reduced when the input or output current of the inverter, which is a load device, is smaller than a predetermined value. Therefore, the discharge lamp which is the load of the inverter device is reduced. Even when the filament is preheated, the inductance value of the inductor device can be reduced by detecting this, and even under a light load such as the filament preheat, the boost chopper circuit does not operate intermittently and abnormal oscillation of the inverter occurs. Can be prevented.

According to the third aspect of the invention, since the power for the inverter control device is obtained from the winding magnetically coupled to the inductor device, the power supply for the control device can be simply constructed, and
Even when the load is light, power can be supplied stably, and inverter control can be performed stably.

In any of the inventions, when there is no load such as when the load device is removed, the on-duty of the switching device is made extremely small as in the conventional case, or the switching device 4 is turned off when the set value is exceeded. By doing so, it is possible to perform overvoltage protection.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply device of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of a discharge lamp lighting device of the present invention.

FIG. 3 is a circuit diagram showing another embodiment of the discharge lamp lighting device of the present invention.

FIG. 4 is a circuit diagram showing a conventional technique.

[Explanation of symbols]

10, 11 ... Load device, 12, 12 '... Inverter, 1
3 ... Discharge lamp, 20 ... Step-up chopper circuit, 25, 35 ... Switching means

Claims (3)

[Claims] 1. A step-up type chopper circuit comprising an inductor device provided with a switchable inductance value, a switching device for controlling the current of the inductor device, and a smoothing capacitor; the output of the chopper circuit is supplied. And a switching device that detects the state of the load device and reduces the inductance value of the inductor device when the load condition seen from the chopper circuit becomes a light load. apparatus. 2. A step-up type chopper circuit having an inductor device provided with a switchable inductance value, a switching device for controlling the current of the inductor device, and a smoothing capacitor; the output of this chopper circuit is supplied. An inverter that is activated by the output of this inverter; an input or output current of the inverter; and when the detected current value is smaller than a predetermined value, the inductance value of the inductor device. A discharge lamp lighting device, comprising: 3. The discharge lamp lighting device according to claim 2, wherein the power supply for the control device of the inverter is obtained from a winding magnetically coupled to the inductor device.