JPH11341818A - Power unit and discharge-lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge-lamp lighting device which is so constituted to prevent the application of stresses to parts, even at the time of the device start up. SOLUTION: Higher harmonic components are reduced by making an input current to be continuously inputted even in a part where a pulsative current is close to zero, by supplying an electric current from a full-wave rectifier circuit 1, when the voltage of the circuit 1 is higher than the charging voltage of a capacitor C3 for charging, or superposing the resonance current of a second capacitor C2 and an inductor L1 upon the input current, when the voltage of the circuit 1 is lower than the charging voltage. During a prescribed period of time after power supply has been turned on, a field effect transistor Q1 is maintained in a turned-off state and another field effect transistor Q2 is turned on, because a capacitor C4 is not charged. Consequently, the input current by-passes the inductor L1 by short-circuiting the inductor L1 and the output of an inverter circuit 3 drops. Since the resonant point between the second capacitor C2 and inductor L1 shifts and the resonance current becomes smaller, the stresses applied to the transistor Q1, etc. are reduced, and the breakdown of a transistor Q3, etc. is prevented, at a discharge-lamp operating device startup.

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 for suppressing harmonic components and a discharge lamp lighting device.

[0002]

2. Description of the Related Art Conventionally, as a power supply of this type, for example, a discharge lamp lighting device described in Japanese Patent Application Laid-Open No. 8-180992 is known.

In the discharge lamp lighting device described in Japanese Patent Application Laid-Open No. 8-180992, a first capacitor is connected to a commercial AC power supply via a diode bridge, and a second capacitor is further connected via a diode. A series circuit of a charging capacitor and an inductor is connected in parallel to the second capacitor, and an inverter circuit is connected between both terminals of the second capacitor.

When the commercial AC power supply is turned on, full-wave rectification is performed by the full-wave rectifier circuit, and in a portion where the voltage of the pulsating current rectified by the full-wave rectifier circuit is higher than the charging voltage of the charging capacitor, The voltage from the full-wave rectifier circuit is supplied to the inverter circuit.

In a part where the voltage of the pulsating current full-wave rectified by the full-wave rectifier circuit is lower than the charging voltage of the charging capacitor, the inductor and the second capacitor resonate, and this resonance current is superimposed on the input current. As a result, the current flows continuously.

As described above, even in a portion where the pulsating current is close to zero, the input current is made continuous to reduce the harmonic components contained in the input current.

[0007]

However, in the case of the configuration described in the above-mentioned Japanese Patent Application Laid-Open No. 8-180992, the charging voltage of the second capacitor rises at the time of starting and stress is applied to components such as the inverter circuit. Or
It has a problem that it may be destroyed.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a power supply device and a discharge lamp lighting device in which stress is not applied to components even at the time of starting or the like.

[0009]

According to a first aspect of the present invention, there is provided a power supply device, comprising: a rectifying means connected to an AC power supply for rectification; a first capacitor connected to an output side of the rectifying means; A diode connected to the output side of the capacitor and connected to the rectifier in a forward polarity, a second capacitor connected in parallel to a series circuit of the diode and the first capacitor, and a second capacitor A series circuit of an inductor and a charging capacitor connected in parallel to the inverter, inverter means connected in parallel to the second capacitor to supply power to a load, switching means for electrically connecting and disconnecting the inductor, The predetermined time after the start is provided with control means for electrically disconnecting the inductor by the switching means. By disconnecting the inductance electrically by quenching means, the resonance state of the second capacitor and the inductor are different, such as no longer a large resonance current flows in the inverter means, preventing will stress the components such as the inverter unit.

According to a second aspect of the present invention, there is provided a power supply device connected to an AC power supply, a rectifier for rectification, a first capacitor connected to an output side of the rectifier, and a first capacitor connected to an output side of the first capacitor. And a diode connected in forward polarity to the rectifier, a second capacitor connected in parallel to the diode, and a series connected first and second series capacitor. A series circuit of an inductor and a charging capacitor, inverter means connected in parallel to the second capacitor and supplying power to a load, switching means for electrically connecting and disconnecting the inductor, and a predetermined time after the start of operation. Control means for electrically disconnecting the inductor by the switching means. By disconnecting the inductance electrically, since the resonant state of the second capacitor and the inductor are different, such as no longer a large resonance current flows in the inverter means, preventing will stress the components such as the inverter unit.

According to a third aspect of the present invention, a first capacitor connected to an AC power supply, a rectifier having an input connected in parallel with the first capacitor, and an output connected to the rectifier. A second capacitor, a series circuit of an inductor and a charging capacitor connected in parallel to the second capacitor, inverter means connected in parallel to the second capacitor to supply power to a load, Switching means for electrically connecting and disconnecting the inductor, and control means for electrically disconnecting the inductor by the switching means for a predetermined time after the operation is started. Since the resonance state of the second capacitor and the inductor is different by electrically disconnecting, Deal of resonance current does not flow, preventing will stress the components such as the inverter unit.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device including the power supply device according to any one of the first to third aspects, wherein the load is a discharge lamp.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a discharge lamp lighting device including a power supply device according to a first embodiment of the present invention will be described with reference to the drawings.

In the discharge lamp lighting device shown in FIG. 1, an input terminal of a full-wave rectifier circuit 1 composed of, for example, a diode bridge as rectifier is connected between output terminals of a commercial AC power supply e. A first capacitor C1 is connected between the output terminals of the full-wave rectifier circuit 1, and a diode D1 having a switching function in the forward polarity from the positive side of the full-wave rectifier circuit 1 is connected. The second capacitor C2 is connected to the full-wave rectifier circuit 1 via the second capacitor C2.

A series circuit of a charging capacitor C3 and an inductor L1 that is charged with a voltage value lower than the maximum instantaneous voltage of the diode D1 is connected in parallel with the second capacitor C2.

A control means 2 is connected to both ends of the second capacitor C2. The control means 2 connects a series circuit of a resistor R1 and a resistor R2 in parallel with the second capacitor C2, A capacitor C4 is connected in parallel to the resistor R2, a gate of the field-effect transistor Q1 is connected to a connection point between the resistors R1 and R2, and a resistor R3 and a resistor are connected in parallel to the second capacitor C2. Connect the series circuit of R4,
The drain and source of the field effect transistor Q1 are connected to this resistor R4, the gate of the field effect transistor Q2 as a switching means is connected to the connection point of the resistors R3 and R4, and the drain and source of the field effect transistor Q2 are connected to the inductor L1. Are connected in parallel.

Further, an inverter circuit 3 as inverter means is connected between both terminals of the second capacitor C2.

The inverter circuit 3 connects a series circuit of a primary winding Tr1 of a leakage flux type inverter transformer Tr and a transistor Q3 as switching means between both terminals of a second capacitor C2. A capacitor C5 is connected in parallel to the winding Tr1, and a reflux diode D2 is connected between the collector and the emitter of the transistor Q3. A drive circuit (not shown) is connected to the base of the transistor Q3.

The secondary winding Tr of the inverter transformer Tr
2 includes a filament FLa of a fluorescent lamp FL serving as a discharge lamp as a load through a DC cut capacitor C6.
, FLb. Furthermore, these filaments FLa
, FLb are connected to a starting capacitor C7.

Next, the operation of the circuit shown in FIG. 1 will be described.

First, when the commercial AC power supply e is turned on, full-wave rectification is performed by the full-wave rectifier circuit 1 and the first and second capacitors C
1, C2 and charging capacitor C3 are charged.

A description will be given of a portion where the voltage of the pulsating current full-wave rectified by the full-wave rectifier circuit 1 is higher than the charging voltage of the charging capacitor C3.

When the transistor Q3 is turned on, a current is supplied from the first capacitor C1 and a part thereof to the primary winding Tr1 of the inverter transformer Tr from the second capacitor C2. Since the combined capacitance of the first capacitor C1 and the second capacitor C2 has sufficient energy to drive the inverter circuit 3, the first capacitor
According to the power supply from C1 and the second capacitor C2,
Energy from the commercial AC power supply e flows as an input current. When the transistor Q3 is on, the inductor
The charging capacitor C3 is charged according to L1. When the voltage of the pulsating current that has been full-wave rectified by the full-wave rectifier circuit 1 is higher than the charging voltage of the charging capacitor C3, the charging capacitor C3 is not discharged to the inverter circuit 3.

Next, a portion where the voltage of the pulsating current full-wave rectified by the full-wave rectifier circuit 1 is lower than the charging voltage of the charging capacitor C3 will be described.

With respect to the charging voltage of the charging capacitor C3,
When the transistor Q3 turns on when the voltage of the pulsating current that has been full-wave rectified by the full-wave rectifier circuit 1 drops, the second capacitor
Power is supplied from C2 to the primary winding Tr1 of the inverter transformer Tr. Then, since the voltage of the second capacitor C2 is insufficient as energy required by the inverter circuit 3, the voltage of the second capacitor C2 decreases. Thereafter, when the voltage of the second capacitor C2 decreases to the voltage of the first capacitor C1, the first capacitor C1 supplies energy to the inverter circuit 3. In addition, an amount corresponding to the discharge amount of the first capacitor C1 flows from the full-wave rectifier circuit 1 as an input current in a form to be supplied from the commercial AC power supply e.
This operation is continued until the transistor Q3 is turned off.

On the other hand, the charging voltage of the charging capacitor C3 is
The release of energy is delayed by the inductance of the inductor L1, and the energy is released immediately before the transistor Q1 is turned on.

Thereafter, when the transistor Q1 turns off, the charging voltage of the charging capacitor C3 is supplied to the inverter circuit 3 by resonance with the inductor L1. Further, as the voltage of the first capacitor C1 decreases with respect to the charging voltage of the charging capacitor C3, the amplitude of the inductor L1 and the charging capacitor C3 increases, and the resonance current peaks at the portion where the input current becomes lowest. Thus, even if the input current decreases, the current flows continuously.

As described above, even in the portion where the pulsating current is close to zero, the input current is made continuous to reduce the harmonic components contained in the input current.

Then, as described above, the inverter circuit 3
Controls the switching of the transistor Q1 at high frequency, and the voltage resonated by the inductance of the primary winding Tr1 of the inverter transformer Tr and the charging capacitor C3 is transmitted to the secondary winding Tr2 and supplied to the fluorescent lamp FL. Then, the capacitor C5 preheats the filaments FLa and FLb of the fluorescent lamp FL, and simultaneously applies the voltage generated by the capacitor C6 to the fluorescent lamp FL to start and turn on the fluorescent lamp FL.

Since the capacitor C4 is not charged for a predetermined time after the power is turned on, the field effect transistor Q1
No gate voltage is applied to the gate of the transistor, and the field-effect transistor Q1 maintains the off state, so that a voltage is applied to the gate of the field-effect transistor Q2, and the field-effect transistor Q2 is turned on. That is, it is electrically separated and bypassed, and the output of the inverter circuit 3 is reduced. As a result, the second capacitor C2
The resonance point between the capacitor L1 and the inductor L1 is shifted, and the resonance current is reduced, so that the stress on the transistor Q1 and the like is reduced, thereby preventing the transistor Q3 and the like from being broken at the time of starting.

The second embodiment will be described with reference to FIG.

The embodiment shown in FIG. 2 differs from the first embodiment shown in FIG. 1 in that a second capacitor C2 is connected in parallel to a diode D1.

The second embodiment shown in FIG. 2 operates similarly to the first embodiment shown in FIG.

Further, a third embodiment will be described with reference to FIG.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 1 in that a full-wave rectifier circuit 1 is connected between a first capacitor C1 and a second capacitor C2.

The third embodiment shown in FIG. 3 operates similarly to the first embodiment shown in FIG.

As described above, if the full-wave rectifier circuit 1 is connected between the first capacitor C1 and the second capacitor C2, the diode D1 for preventing backflow is not required, and the circuit configuration is simplified.

[0038]

According to the power supply device of the first aspect, the resonance state of the second capacitor and the inductor is different for a predetermined time after the start of starting by electrically disconnecting the inductance by the switching means. Thus, it is possible to prevent a large resonance current from flowing in the device and the like, thereby preventing stress on components such as the inverter means.

According to the power supply device of the second aspect, the resonance state of the second capacitor and the inductor is different by electrically disconnecting the inductance by the switching means for a predetermined time after the start of the starting. It is possible to prevent a large resonance current from flowing and prevent stress on parts such as the inverter means.

According to the third aspect of the present invention, the resonance state of the second capacitor and the inductor is different from each other by electrically disconnecting the inductance by the switching means for a predetermined time after the start of the starting operation. It is possible to prevent a large resonance current from flowing and prevent stress on parts such as the inverter means.

According to the discharge lamp lighting device of the fourth aspect,
Since the load includes the power supply device according to any one of claims 1 to 3, which is a discharge lamp, the respective effects can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a discharge lamp lighting device according to the second embodiment.

FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to a third embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Full-wave rectification circuit as rectification means 2 Control means 3 Inverter circuit as inverter means C1 First capacitor C2 Second capacitor C3 Charging capacitor D1 Diode e Commercial AC power supply FL Fluorescent lamp L1 as discharge lamp as load Inductor Q2 Field effect transistor as switching means

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H05B 41/29 H05B 41/29 C

Claims (4)

[Claims] A rectifier connected to an AC power supply for rectification; a first capacitor connected to an output of the rectifier; and a rectifier connected to an output of the first capacitor. A diode connected in a forward polarity, a second capacitor connected in parallel to a series circuit of the diode and the first capacitor, and a series of an inductor and a charging capacitor connected in parallel to the second capacitor A circuit; an inverter connected in parallel to the second capacitor to supply power to a load; a switching unit electrically connecting and disconnecting the inductor; and a switching unit that switches the inductor by the switching unit for a predetermined time after starting operation. A power supply device comprising: control means for electrically disconnecting the power supply. 2. A rectifier connected to an AC power supply for rectification, a first capacitor connected to an output of the rectifier, and a rectifier connected to an output of the first capacitor. A diode connected in a forward polarity; a second capacitor connected in parallel to the diode; a series of an inductor and a charging capacitor connected in parallel to a series circuit of the first capacitor and the second capacitor. A circuit; an inverter connected in parallel to the second capacitor to supply power to a load; a switching unit electrically connecting and disconnecting the inductor; and a switching unit that switches the inductor by the switching unit for a predetermined time after starting operation. A power supply device comprising: control means for electrically disconnecting the power supply. 3. A first capacitor connected to an AC power supply, a rectifier having an input side connected in parallel with the first capacitor, a second capacitor connected to an output side of the rectifier, A series circuit of an inductor and a charging capacitor connected in parallel to the second capacitor; an inverter connected in parallel to the second capacitor to supply power to a load; and electrically connecting and disconnecting the inductor. A power supply device comprising: switching means; and control means for electrically disconnecting the inductor by the switching means for a predetermined time after the start of operation. 4. A discharge lamp lighting device comprising the power supply device according to claim 1, wherein the load is a discharge lamp.