JPH11297487A - Power supply and discharge lamp lighting device - Google Patents

Abstract

(57) [Problem] To provide a discharge lamp lighting device in which stress is not applied to components even at the time of starting or load change. SOLUTION: When 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, the current is supplied from the full-wave rectifying circuit 1; By superimposing the resonance current of the inductor L1, the input current is continued even in a portion where the pulsating current is close to zero, and the harmonic component is reduced. The current flowing through the fluorescent lamp FL is fed back by the current transformer CT, and when an overcurrent occurs at the time of starting or load fluctuation, the capacitor C7 is charged and when the voltage reaches a predetermined voltage, the Zener diode ZD1 turns on and the field effect transistor Q2 is turned on. Turns on, short-circuits the inductor L1, and lowers the output of the inverter circuit 2.

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 Japanese Patent Application Laid-Open No. Hei 8-180992, the charging voltage of the second capacitor rises at the time of starting or a change in load, and components such as an inverter circuit are increased. Has a problem that stress may be applied to the device or the device 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 that prevent stress from being applied to components even at the time of starting or a change in load.

[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 in a forward direction with respect to the rectifier; a second capacitor connected in parallel to a series circuit of the diode and the first capacitor; A series circuit of an inductor and a charging capacitor connected in parallel to the inverter; an inverter connected in parallel to the second capacitor and operating at a higher frequency than the AC power supply to supply power to a load; A switching means connected in parallel, and a control for closing the switching means and short-circuiting the inductor when the load becomes different from a steady state. When the load is in a state different from the steady state, the switching means is closed and the inductance is short-circuited, so that the resonance state of the second capacitor and the inductor is different. This prevents a resonance current from flowing and stressing components such as the inverter means.

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. A diode connected in a forward direction with respect to the rectifier, a second capacitor connected in parallel to the diode, and a series connection of the first capacitor and the second capacitor in parallel. A series circuit of an inductor and a charging capacitor; an inverter connected in parallel to the second capacitor, operating at a higher frequency than the AC power supply and supplying power to a load; and a switching connected in parallel to the inductor. Means, and control means for closing the switching means and short-circuiting the inductor when the load becomes different from a steady state. When the load becomes different from the steady state, the switching means is closed and the inductance is short-circuited, so that the resonance state of the second capacitor and the inductor is different, so that a large resonance current does not flow through the inverter means and the like. Also, it is possible to prevent parts such as inverter means from being stressed.

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, and connected to the second capacitor in parallel to operate at a higher frequency than the AC power supply and supply power to a load. And a switching means connected in parallel to the inductor, and a control means for closing the switching means and short-circuiting the inductor when the load becomes different from a steady state. When the load becomes different from the steady state, the switching means is closed and the inductance is short-circuited, so that the second capacitor is closed. Since the resonant state of the capacitors and inductors 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 fourth aspect of the present invention, there is provided a power supply unit connected to an AC power supply for rectification, a first capacitor connected to an output side of the rectification means, and connected to an output side of the first capacitor. A diode connected in a forward direction to the rectifier, a second capacitor connected in parallel to a series circuit of the diode and the first capacitor, and a diode connected in parallel to the second capacitor. A series circuit of an inductor and a charging capacitor; inverter means connected in parallel to the second capacitor, operating at a higher frequency than the AC power supply and supplying power to a load; and a capacitor for varying the capacity of the second capacitor Variable means,
Control means for changing the capacity of the second capacitor when the load is in a state different from the steady state; and when the load is in a state different from the steady state, the switching means is closed to short-circuit the inductance. Thereby, since the resonance state of the second capacitor and the inductor is different, a large resonance current does not flow to the inverter means or the like, thereby preventing stress on parts such as the inverter means.

According to a fifth aspect of the present invention, there is provided a power supply device connected to an AC power supply, rectifying means for rectification, a first capacitor connected to an output side of the rectifying means, and connected to an output side of the first capacitor. A diode connected in a forward direction with respect to the rectifier, a second capacitor connected in parallel to the diode, and a series connection of the first capacitor and the second capacitor in parallel. A series circuit of an inductor and a charging capacitor; inverter means connected in parallel to the second capacitor, operating at a higher frequency than the AC power supply and supplying power to a load; and a capacitor for varying the capacity of the second capacitor Variable means,
Control means for changing the capacity of the second capacitor when the load is in a state different from the steady state; and when the load is in a state different from the steady state, the switching means is closed to short-circuit the inductance. Thereby, since the resonance state of the second capacitor and the inductor is different, a large resonance current does not flow to the inverter means or the like, thereby preventing stress on parts such as the inverter means.

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 control means operates in accordance with the output of the rectification means, and the output of the rectification means changes with a change in load. Therefore, it is easily controlled according to the output of the rectifier.

According to a seventh 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 sixth aspects.
Each function is performed.

[0016]

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 or the like as rectifier is connected between output terminals of a commercial AC power supply e. Between the output terminals of the full-wave rectifier circuit 1, a first capacitor C1 is connected, and a diode D1 having a switching function in the forward direction from the positive electrode 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 charged with a voltage value lower than the maximum instantaneous voltage of the diode D1 is connected in parallel with the second capacitor C2.

Further, an inverter circuit 2 as inverter means is connected between both terminals of the second capacitor C2.

The inverter circuit 2 includes a primary winding Tr1 of an inverter transformer Tr and a transistor as switching means between both terminals of a second capacitor C2.
A series circuit of Q1 is connected, a capacitor C4 is connected in parallel to the primary winding Tr1, and a freewheeling diode D2 is connected between the collector and the emitter of the transistor Q1. A drive circuit (not shown) is connected to the base of the transistor Q1.

The secondary winding Tr of the inverter transformer Tr
2 is connected to filaments FLa and FLb of a fluorescent lamp FL as a discharge lamp via a DC cut capacitor C5 and a primary winding CT1 of a current transformer CT. further,
A starting capacitor C6 is connected to these filaments FLa and FLb.

Further, a control means 3 is connected to the secondary winding CT2 of the current transformer CT. The control means 3 has a resistor R1 and a capacitor C7 connected in parallel via a diode D3, and a diode D3 and a resistor R1. The connection point of the capacitor C7 is connected via a Zener diode ZD1 to the gate of a field-effect transistor Q2 as a switching means, and the drain and source of the field-effect transistor Q2 are connected to both ends of an inductor L1. A resistor R2 is connected between the gate and the source of Q2.

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 to charge the first, second and charging capacitors C1, C2, C3.

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

When the transistor Q1 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 2, the first capacitor C1
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 Q1 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 2.

Next, 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 lower than the charging voltage of the charging capacitor C3.

With respect to the charging voltage of the charging capacitor C3,
When the transistor Q1 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 2, 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 2. In addition, an amount corresponding to the discharge amount of the first capacitor 1 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 Q1 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 is turned off, the charging voltage of the charging capacitor C3 is supplied to the inverter circuit 2 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 2
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.

The fluorescent lamp FL is controlled by the current transformer CT.
The capacitor C7 is charged via the diode D3 by feedback of the current flowing through the diode D3.When an overcurrent occurs at the time of starting or load fluctuation, the capacitor C7 is charged and when the predetermined voltage is reached, the Zener diode ZD1 is turned on. The field effect transistor Q2 is turned on, the inductor L1 is short-circuited and bypassed, and the output of the inverter circuit 2 decreases. This allows
The resonance point between the second capacitor C2 and the inductor L1 is shifted,
Since the resonance current is reduced, stress on the transistor Q1 and the like is reduced, thereby preventing the transistor Q1 and the like from being broken.

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.

Then, 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 backflow preventing diode D1 becomes unnecessary, and the circuit configuration is simplified.

The fourth embodiment will be described with reference to FIG.

The embodiment shown in FIG. 4 is different from the embodiment shown in FIG. 1 in that the control means 3 having the current transformer CT is replaced with a control circuit connected to both ends of the full-wave rectifier circuit 1 via a diode D1. This is a method using the means 4.

The control means 4 connects a series circuit of a resistor R3 and a resistor R4 to both ends of the full-wave rectifier circuit 1 via a diode D1, and connects a connection point between the resistors R3 and R4 via a zener diode ZD2. To connect the gate of the field effect transistor Q2,
The resistor R5 is connected between the sources.

The operation of the fourth embodiment shown in FIG. 4 is basically the same as that of the first embodiment shown in FIG. 1, but when the load becomes heavy due to a start-up or a load change. Since the voltage of the full-wave rectifier circuit 1 also increases, the voltage of the full-wave rectifier circuit 1 is detected by the resistors R3 and R4, and the voltage of the full-wave rectifier circuit 1 rises to a predetermined value or more, and the Zener diode ZD2 turns on. Then, the inductor L1 is short-circuited. Thus, by detecting the voltage of the full-wave rectifier circuit 1, a control circuit can be easily configured.

The fifth embodiment will be described with reference to FIG.

The embodiment shown in FIG. 5 differs from the fourth embodiment shown in FIG. 4 in that a second capacitor C2 is connected in parallel with the diode D1.

The operation of the fifth embodiment shown in FIG. 5 is similar to that of the fourth embodiment shown in FIG.

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

The embodiment shown in FIG. 6 differs from the embodiment shown in FIG. 4 in that the full-wave rectifier circuit 1 is connected between the first capacitor C1 and the second capacitor C2.

The operation of the sixth embodiment shown in FIG. 6 is similar to that of the fourth embodiment shown in FIG.

As described above, when 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.

The seventh embodiment will be described with reference to FIG.

The embodiment shown in FIG. 7 differs from the embodiment shown in FIG. 1 or 4 in that a series circuit of a capacitor C8 and a field effect transistor Q3 as switching means is connected in parallel with the second capacitor C2. Connected and the resistance of the control means 5 in parallel with the transistor Q1.
By connecting a series circuit of R6 and resistor R7, this transistor
Connect the connection point of Q6 and transistor Q7 with Zener diode ZD.
3 Field-effect transistor as a variable capacitance means via
The resistor R8 is connected between the gate and the source of the field-effect transistor Q3.

The operation of the seventh embodiment shown in FIG. 7 is similar to that of the first embodiment shown in FIG. 1 or the fourth embodiment shown in FIG. The rise causes the Zener diode ZD3 to turn on, and the field effect transistor Q3 to turn on, whereby the capacitor C8 is connected in parallel to the second capacitor C2, and the capacitance of the second capacitor C2 changes apparently. As a result, the resonance point with the inductor L1 changes, the current supplied to the inverter circuit 2 decreases, the stress on the transistor Q1 decreases, and the transistor Q1 is prevented from being destroyed.

The same effect can be obtained even if the field effect transistor Q2 and the field effect transistor Q3 are configured to operate in conjunction with each other.

Further, an eighth embodiment will be described with reference to FIG.

The embodiment shown in FIG. 8 differs from the embodiment shown in FIG. 7 in that the full-wave rectifier circuit 1 is connected between the first capacitor C1 and the second capacitor C2.

The operation of the eighth embodiment shown in FIG. 8 is similar to that of the fourth 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.

In any of the above-described embodiments, even when the voltage of the commercial AC power supply e that has been full-wave rectified by the full-wave rectifier circuit 1 is low, the resonance current is generated by the resonance of the series circuit of the inductor L1 and the charging capacitor C3. Can be generated, and at the time of starting or when a load fluctuation occurs, by changing the resonance frequency of the second capacitor C2 and the inductor L1, the resonance current is reduced and the output of the inverter circuit 2 is reduced. Thus, the stress of the transistor Q1 is reduced to prevent destruction.

[0061]

According to the first aspect of the present invention, when the load becomes different from the normal state, the switching means is closed and the inductance is short-circuited, so that the resonance state of the second capacitor and the inductor is changed. Due to the difference, a large resonance current does not flow through the inverter means or the like, and it is possible to prevent stress from being applied to parts such as the inverter means.

According to the second aspect of the present invention, when the load is in a state different from the normal state, the switching means is closed to short-circuit the inductance, so that the resonance state of the second capacitor and the inductor is different. In addition, it is possible to prevent a large resonance current from flowing to the inverter means and the like, thereby preventing the components such as the inverter means from being stressed.

According to the third aspect of the present invention, when the load is in a state different from the normal state, the resonance state of the second capacitor and the inductor is different by closing the switching means and short-circuiting the inductance. In addition, it is possible to prevent a large resonance current from flowing to the inverter means and the like, thereby preventing the components such as the inverter means from being stressed.

According to the power supply device of the fourth aspect, when the load is in a state different from the steady state, the resonance state of the second capacitor and the inductor is different by closing the switching means and shorting the inductance. In addition, it is possible to prevent a large resonance current from flowing to the inverter means and the like, thereby preventing the components such as the inverter means from being stressed.

According to the power supply device of the fifth aspect, when the load is in a state different from the steady state, the resonance state of the second capacitor and the inductor is different by closing the switching means and shorting the inductance. In addition, it is possible to prevent a large resonance current from flowing to the inverter means and the like, thereby preventing the components such as the inverter means from being stressed.

According to the power supply device of the sixth aspect, in addition to the power supply device of any one of the first to fifth aspects, the output of the rectifying means changes with a change in load, so that control is easily performed according to the output of the rectifying means. it can.

Since the discharge lamp lighting device according to the seventh aspect includes the power supply device according to any one of the first to sixth aspects, 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;

FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to a fourth embodiment;

FIG. 5 is a circuit diagram showing a discharge lamp lighting device according to a fifth embodiment;

FIG. 6 is a circuit diagram showing a discharge lamp lighting device according to a sixth embodiment;

FIG. 7 is a circuit diagram showing a discharge lamp lighting device according to a seventh embodiment of the present invention.

FIG. 8 is a circuit diagram showing a discharge lamp lighting device according to an eighth embodiment of the present invention.

[Explanation of symbols]

 1 Full-wave rectifier circuit as rectifier means 2 Inverter circuit as inverter means 3,4,5 Control means C1 First capacitor C2 Second capacitor C3 Charging capacitor D1 Diode e Commercial AC power supply L1 Inductor Q2 As switching means Field effect transistor Q3 Field effect transistor as variable capacitance means

Claims (7)

[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 direction; 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, operating at a higher frequency than the AC power supply, and supplying power to the load; a switching unit connected in parallel to the inductor; Control means for closing the switching means and short-circuiting the inductor when the state becomes different from the normal state. Apparatus. 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 direction, 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, operating at a higher frequency than the AC power supply, and supplying power to the load; a switching unit connected in parallel to the inductor; Control means for closing the switching means and short-circuiting the inductor when the state becomes different from the normal state. Apparatus. 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; inverter means connected in parallel to the second capacitor, operating at a higher frequency than the AC power supply and supplying power to a load; A power supply device, comprising: switching means connected in parallel to the inductor; and control means for closing the switching means and short-circuiting the inductor when the load becomes different from a steady state. . 4. 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 direction; 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 and operating at a higher frequency than the AC power supply to supply power to the load; a capacitance variable unit configured to vary the capacitance of the second capacitor; A power supply device comprising: a control unit that changes a capacity of the second capacitor when the state becomes different from a normal state. 5. A rectifier for rectification connected to an AC power supply, a first capacitor connected to an output side of the rectifier, and a rectifier connected to an output side of the first capacitor. A diode connected in a forward direction, 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 and operating at a higher frequency than the AC power supply to supply power to the load; a capacitance variable unit configured to vary the capacitance of the second capacitor; A power supply device comprising: a control unit that changes a capacity of the second capacitor when the state becomes different from a normal state. 6. The power supply device according to claim 1, wherein the control means operates in accordance with an output of the rectification means. 7. A discharge lamp lighting device comprising the power supply device according to claim 1.