JP2000312483A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the loss in a switching element by reducing the peak factor of the current flowing to a load circuit. SOLUTION: A power unit is provided with a rectifier DB, a diode D11 the anode of which is forwardly connected to the positive, output terminal of the rectifier DB, and a filter capacitor C10 connected between the cathode of the diode D11 and the negative output terminal of the rectifier DB. The power unit is also provided with a diode D12, the anode of which is forwardly connected to the cathode of the diode D11, FETs Q1 and Q2 which are connected in series between the cathode of the diode D12 and the negative output terminal of the rectifier DB, and a control circuit 10 which controls the turning on/off of the FETs Q1 and Q2. In addition, the power unit is also provided with a transformer T11, having a primary winding n11 connected between the junction of the FETs Q1 and Q2 and the positive output terminal of the rectifier DB and a secondary winding connected to a load circuit 11, a capacitor C11 connected in parallel with the diode D11 or rectifier DB, and a capacitor C12 connected in parallel with the diode D12.

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 performing rectification and smoothing of AC power into DC power, converting a DC voltage obtained by the rectification and smoothing into a high frequency voltage, and supplying a high frequency power to a load circuit. It is.

[0002]

2. Description of the Related Art FIG. 54 is a schematic structural view of such a conventional power supply device (see Japanese Patent Application No. 9-88526).

This circuit configuration has a rectifier DB for full-wave rectification of an AC power supply AC, and a capacitor C1 having a relatively small capacity is connected between the output terminals of the rectifier DB. Also,
It comprises a smoothing capacitor C2 and a series circuit of a pair of transistors Tr1 and Tr2 connected in parallel with the capacitor C2.
B is connected to the DC output terminal on the low potential side. Rectifier DB
High-potential side DC output terminal and transistors Tr1, Tr
The primary winding of the transformer T1 is connected between the two connection points. A load circuit 11 is connected to the secondary winding of the transformer T1, and the load circuit 11 includes a discharge lamp (fluorescent lamp) FL having one end of a filament connected to both ends of the secondary winding of the transformer T1, and a discharge lamp FL. And a capacitor C111 for preheating / resonance connected between the non-power supply side ends of the respective filaments.
A resonance circuit is constituted by the leakage inductance 1 and the capacitor C111. In FIG. 54, bipolar transistors are used for the transistors Tr1 and Tr2, and diodes D1 and D2 are connected in anti-parallel, respectively. The transistors Tr1 and Tr2 are alternately turned on / off at a switching frequency sufficiently higher than the power supply frequency by a control circuit (not shown).

[0004] Considering the steady state operation,
Since the capacitor C2 is charged in the steady barking mode, when the transistor Tr1 is turned on, a current flows through the path of the capacitor C2, the transistor Tr1, the primary winding of the transformer T1, the capacitor C1, and the capacitor C2, and passes through the transformer T1. Thus, power is supplied to the load circuit 11. At this time, the voltage V _C2 across the capacitor C2 is equal to the voltage of the transformer T1.
Rises due to resonance with the leakage inductance. When the transistor Tr1 is turned off, the energy stored in the primary winding of the transformer T1 is released, current continues to flow through the path of the transformer T1, the capacitor C1, the diode D2 and the transformer T1, and the voltage across the capacitor C1 further increases.

Subsequently, when the transistor Tr2 is turned on,
Leakage inductance of transformer T1 and capacitor C11
1 and C1, a resonance current flows through the path of the capacitor C1, the transformer T1, the transistor Tr2 and the capacitor C1. At this time, the voltage V _C1 across the capacitor C1 starts to fall, and when this voltage becomes lower than the DC output voltage of the rectifier DB, the input current is drawn from the AC power supply AC, and the AC power supply AC, the rectifier DB, and the transformer T1 , A current flows through the path of the transistor Tr2, the rectifier DB, and the AC power supply AC. When the transistor Tr2 is turned off, the AC power supply AC, the rectifier DB, the transformer T1, the diode D1, the capacitor C2, and the rectifier D
Current continues to flow through the path of B and the AC power supply AC, and when the transistor Tr1 is turned on, the state returns to the initial state.

FIG. 55 shows an operation waveform diagram of the voltage Vs of the AC power supply AC over one cycle. The waveform of the voltage V _C1 across the capacitor C1 and the current I flowing through the primary winding of the transformer T1 are arranged in order from the top. The waveform of _T1, the waveform of the input current Iin from the AC power supply AC, and the discharge lamp FL of the load circuit 11
3 shows a waveform of a lamp current I _FL flowing through the lamp.

By the way, although not shown in FIG. 54, in a circuit for supplying this kind of high-frequency power to the load circuit 11, in order to prevent high-frequency components from being mixed into the AC power supply AC, the AC power supply AC and the rectifier DB are connected to each other. It is common practice to insert a high frequency blocking filter circuit between them. By providing such a filter circuit, the AC power supply AC
55 has a sinusoidal waveform at the bottom of FIG. That is, only the envelope component “without Iin filter” shown in FIG. 55 is extracted, and an input current substantially proportional to the voltage Vs of the AC power supply AC is obtained.

The input current waveform depends on the capacitance of the capacitor C1. For example, when the amplitude of the voltage between both ends of the capacitor C2 becomes large, the polarity is inverted during the period when the input current Iin flows from the AC power supply AC to the high frequency blocking filter as shown in FIG. . When the amplitude of the voltage between both ends of the capacitor C1 becomes small, a pause section occurs in the input current to the high frequency blocking filter as shown in FIG. In any case, noise is mixed into the AC power supply AC.
The capacitor C1 has an input current as shown in FIG.
Setting not only the input current harmonics are reduced, but also the input power factor is increased.

Japanese Patent Application Laid-Open No. H10-14257 discloses that a second impedance element is connected between an output terminal of a rectifier and a contact point of a diode, and a series circuit including a coupling capacitor and an inductor. There is disclosed a power supply device in which a load circuit is connected to both ends of a second impedance via a power supply.

[0010]

However, in the conventional power supply device shown in FIG. 54, the voltage applied to the primary winding of the transformer T1 is the difference between the voltage V _C2 and the voltage V _C1 , Since V _C2 is a substantially constant DC voltage, the voltage V
_The waveform is obtained by removing the DC component from _C1 . Therefore, as shown in FIG. 55, the load current I _FL is high at the valley of the pulsating flow and becomes small at the ridge of the pulsating flow. To lower the crest factor of the load current I _FL , the voltage V _C2 must be increased, and the capacitor C2
The cost is increased by increasing the breakdown voltage. Further, since the input current and the resonance current are added when the transistor Tr2 is turned on, the current flowing through the transistor Tr2 at the moment when the transistor Tr2 is turned off increases. In particular, it becomes very large at the pulsating peak where the input current reaches its peak. For this reason, the transistor Tr2 due to the high V _C2 and the large switch current
However, there has been a problem that the switching loss becomes large and the circuit efficiency becomes low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply device in which the input current harmonics are small, the crest factor of the current flowing through the load circuit is small even if the voltage of the smoothing capacitor is low, and the loss of the switching element is reduced. It is in.

[0012]

According to a first aspect of the present invention, there is provided a power supply apparatus comprising: a rectifier for rectifying AC power into DC power; one output terminal of one end of the rectifier in a forward direction; Is connected to the first diode, and the first diode is connected to the first diode.
A smoothing capacitor connected between the other end of the diode and the other output terminal of the rectifier; a second diode connected to the other end of the first diode in a forward direction; A pair of switching elements connected in series between one end and the other output terminal of the rectifier, a diode connected in anti-parallel with each of the pair of switching elements, a connection point of the pair of switching elements, and the rectifier And a transformer having a primary winding connected between the first and second output terminals and having a secondary winding connected to a load circuit, and a first and a second parallel connection with the first and second diodes, respectively. And a second capacitor.

In this configuration, the voltage generated at the first and second capacitors makes the peak value of the voltage applied to the primary winding of the transformer substantially constant, and reduces the crest factor of the current flowing through the load circuit. As a result, the loss of the switching element can be reduced.

According to a second aspect of the present invention, there is provided a power supply device comprising: a rectifier for rectifying AC power to DC power; a first diode having one end connected to one output terminal of the rectifier in a forward direction; A smoothing capacitor connected between the other end of the rectifier and the other output terminal of the rectifier;
A second diode having one end connected to the other end of the diode in the forward direction; a pair of switching elements connected in series between the other end of the second diode and the other output terminal of the rectifier; A diode connected in anti-parallel to each of the switching elements, a primary winding connected between a connection point of the pair of switching elements and one output terminal of the rectifier, and connected to a load circuit;
A transformer having a secondary winding, a first capacitor connected between both output terminals of the rectifier, and a second capacitor connected in parallel with the second diode.

Also in this configuration, the voltage generated at the first and second capacitors makes the peak value of the voltage applied to the primary winding of the transformer substantially constant, and the peak factor of the current flowing through the load circuit decreases. As a result, the loss of the switching element can be reduced.

The first winding connected in parallel with the primary winding.
A configuration including an inductor may be adopted. Even with this configuration, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

Further, a second coil connected in series with the secondary winding is provided.
An inductor, wherein the load circuit is configured by a parallel circuit of a load and a capacitor;
A configuration connected between both ends of the inductor may be adopted. Even with this configuration, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

Further, the transformer may have a leakage inductance component as the second inductor. Even with this configuration, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

Further, a control means for performing on / off control so that at least one of a switching frequency and an on-duty ratio can be changed for the pair of switching elements may be provided (claim 6). According to this configuration, it is possible to adjust the amount of power supplied to the load circuit. If the load circuit includes a discharge lamp,
Control such as starting and dimming can be performed. further,
It is possible to prevent the switching element and the like from being destroyed due to the abnormal boosting of the DC voltage due to the fluctuation of the power consumption.

[0020] Further, there is provided control means for changing at least one of a switching frequency and an on-duty ratio in accordance with the voltage fluctuation of the AC power to perform on / off control for the pair of switching elements. When the rated output is supplied to the load circuit, the on-duty ratio is mainly controlled, while when the output to the load circuit is reduced, the switching frequency is mainly controlled. 7). According to this configuration, even if the voltage of the AC power fluctuates, the load current can be kept within an allowable range.

A voltage detecting means for detecting a voltage between both ends of the smoothing capacitor; and an on / off switch for the pair of switching elements so that at least one of a switching frequency and a duty ratio can be changed according to a detection result of the voltage detecting means. It may be configured to include control means for performing control (claim 8). In this configuration, when the circuit is operating normally, a stable output is obtained by controlling the detected voltage to a predetermined level, and when the load circuit includes a discharge lamp, the output of the illumination is controlled. Flicker can be suppressed. In addition, when an abnormality occurs in the circuit, it is possible to prevent the element from being destroyed due to an overvoltage by performing control such as stopping the oscillation by detecting an abnormal increase in the voltage.

Further, a configuration may be adopted in which a clamp circuit for limiting the applied voltage to a predetermined voltage is provided. According to this configuration, it is possible to prevent application of an overvoltage to the circuit element and prevent destruction of the circuit element.

Further, a configuration may be provided that includes a capacitor connected in parallel with at least one of the pair of switching elements at least in high frequency. According to this configuration, it is possible to reduce the loss of the switching element, improve the circuit efficiency, and reduce noise and cost.

Further, for a switching element connected between both output terminals of the rectifier via the primary winding,
A configuration may be provided that includes control means for performing on-control when the voltage of the switching element and the voltage across the smoothing capacitor are substantially equal (claim 11). According to this configuration, it is possible to suppress an increase in loss at the time of switch-on.

Further, voltage detecting means for detecting a voltage between both ends of a switching element connected between both output terminals of the rectifier via the primary winding, and the pair of voltage detecting means utilizing the detection result of the voltage detecting means. And a control unit for performing on / off control of the switching element.
2). According to this configuration, it is possible to suppress an increase in loss at the time of switch-on.

Further, the load circuit may be configured to have at least two resonance frequencies and at least one anti-resonance frequency. According to this configuration, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

The load circuit has a third capacitor connected to both ends of the secondary winding via a second inductor, and one end connected to both ends of the third capacitor via a third inductor. A discharge lamp having a pair of filaments and a fourth capacitor connected between the other ends of the pair of filaments.
4). According to this configuration, for example, when the load circuit includes a thin tube type discharge lamp, optimal preheating control becomes possible, and suitable starting and lighting become possible.

Further, the transformer may have a leakage inductance component as the second inductor. According to this configuration, for example, when the load circuit includes a thin tube type discharge lamp, optimal preheating control becomes possible, and suitable starting and lighting become possible.

The load circuit includes a discharge lamp. When the discharge lamp is dimly lit, the control circuit lowers the DC voltage of the smoothing capacitor to a value lower than the rated voltage. When controlling at least one of the switching frequency and the duty ratio of the pair of switching elements so as to preheat the filament of the discharge lamp, the DC voltage of the smoothing capacitor is set to a value higher than the rated lighting. A configuration may be adopted in which at least one of the switching frequency and the duty ratio of the pair of switching elements is controlled so as to be as follows. According to this configuration, for example, when the load circuit includes a thin tube type discharge lamp, optimal preheating control becomes possible,
Suitable starting and lighting are enabled.

Further, the load circuit comprises a capacitor connected to both ends of the secondary winding, and a discharge lamp having a pair of filaments each having one end connected to both ends of the capacitor. A configuration in which a preheating resonance circuit is connected between both ends may be adopted.
7). According to this configuration, for example, when the load circuit includes a thin tube type discharge lamp, optimal preheating control becomes possible, and suitable starting and lighting become possible.

The power supply device according to the present invention is a rectifier for rectifying AC power to DC power, a first diode having one end connected to one output terminal of the rectifier in a forward direction, and a first diode. A smoothing capacitor connected between the other end of the rectifier and the other output terminal of the rectifier;
A second diode having one end connected to the other end of the diode in the forward direction; a pair of switching elements connected in series between the other end of the second diode and the other output terminal of the rectifier; A diode connected in anti-parallel to each of the switching elements, a first inductance connected between a connection point of the pair of switching elements and one output terminal of the rectifier, and a first circuit together with a load circuit;
A second inductance connected in parallel with the inductance; and first and second capacitors respectively connected in parallel with the first and second diodes.

In this configuration, the voltage generated at the first and second capacitors makes the peak value of the voltage applied to the first inductance substantially constant, and the peak factor of the current flowing through the load circuit decreases. As a result, the loss of the switching element can be reduced.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a power supply device according to a first embodiment of the present invention, FIGS. 2 to 6 are explanatory diagrams of the operation of the power supply device, and FIGS. FIG. 3 is a signal waveform diagram of each part during operation.
An embodiment will be described.

As shown in FIG. 1, this power supply device has a rectifier DB for full-wave rectification of AC power from an AC power supply AC to DC power, and an anode connected to a positive output terminal of the rectifier DB in a forward direction. (A first diode), a cathode of the diode D11 and a rectifier DB
, A diode D12 (second diode) having a cathode connected to the cathode of the diode D11 in a forward direction, a cathode of the diode D12 and a rectifier DB.
FET Q1, connected in series with the negative output terminal of
Q2 (a pair of switching elements) and these FETs Q
1, a control circuit 10 for performing on / off control of Q2, and FE
A transformer T11 having a primary winding n11 connected between a connection point of TQ1 and Q2 and a positive output terminal of the rectifier DB and having a secondary winding n12 connected to the load circuit 11, and a diode D11, D12 and capacitors C11 and C12 respectively connected in parallel.

However, each of the FETs Q1 and Q2 is, for example, a MOSFET, has a source / substrate connected, and has a structure having a parasitic diode in which a cathode and an anode are connected (in reverse parallel connection) to a drain and a source, respectively. Has become.

The control circuit 10 operates at a switching frequency sufficiently higher than the frequency of the AC power supply AC to operate the FE.
TQ1 and Q2 are turned on / off alternately. That is, the switching frequency is set to such an extent that the voltage of the AC power supply AC can be considered constant during one cycle.

The load circuit 11 is connected between a discharge lamp (fluorescent lamp) FL having a pair of filaments, one end of which is connected to both ends of the secondary winding n12, and the other end of the pair of filaments. And a preheating / resonance capacitor C111.

Further, the transformer T11 is a leakage transformer, and has a configuration in which a resonance circuit is formed by the leakage inductance of the transformer T1 and the capacitor C111.

Next, the circuit operation of the power supply device having the above configuration will be described.
This will be described with reference to FIGS. However,
The time point t11 of 7 indicates the ON time point of the FET Q2. Also,
Voltage V in FIG._Q1, V_Q2, V_C11, V_C12And electricity
Style I_T11, I_Q1, I_Q2, Iin are the same symbols as shown in FIG.
Signal. Similarly, the voltage V in FIG.
_C11, V_C12, V_T11And the current I_T11, Each of Iin
Also correspond to the signal of the same sign shown in FIG. Furthermore, the figure
8 current I_FLIndicates a current flowing through the discharge lamp FL.

In a steady state after the charging of the capacitor C10, at the time t12 shown in FIG. 7, the capacitors C10, C11,
A current _IT11 flows through the path of the next winding n11, the FET Q2 and the capacitor C10, and the capacitor C10 serves as a power supply, the capacitor C11 is charged and its voltage _VC11 increases, and power is supplied to the load circuit 11 via the transformer T11. Is supplied.

Thereafter, the voltage V _C11 of the capacitor _C11 is equal to the voltage V _{C10 of the} capacitor _C10 and the output voltage of the rectifier DB.
When the voltage rises to the difference voltage (V _C10 − | Vs |) with respect to | Vs | (time t13 in FIG. 7), as shown by the arrow line in FIG. 3, the AC power supply AC, the rectifier DB, the primary winding n11, and the FET Q2 , The current _IT11 flows through the path of the rectifier DB and the AC power supply AC, and the input current Iin is drawn into the power supply device from the AC power supply AC. Here, from FIG. 7, in the period in which the FETs Q1 and Q2 repeat ON / OFF once, the period in which the input current Iin is drawn from the AC power supply AC (time t13 to t1).
It can be seen that 5) exists.

Thereafter, when the FET Q2 is turned off (FIG. 7)
At time t14), as shown by the arrow line in FIG. 4, the transformer T11 storing the energy by the current flowing through the primary winding n11 and the AC power supply AC serve as the power supply, and the AC power supply AC, the rectifier DB, Next winding n11, parasitic diode of FET Q1, capacitor C12, capacitor C1
0, the current I _{T11 in} the path of the rectifier DB and the AC power supply AC.
Flows, and the capacitor C1 is drawn while drawing the input current Iin.
0 and C12 are charged. At this time, the capacitor C12
As shown in FIG. 7, the voltage V _C12 rises due to the resonance action with the leakage inductance of the transformer T11. Further, the FET Q1 is turned on.

When the FET Q1 is turned on, the transformer T1
1 and the capacitors C11 and C1
2 and C111, the capacitor C11, capacitor C12, FET
A resonance current flows through the path of Q1, the primary winding n11 and the capacitor C11. Thereafter, the capacitors C11 and C12
The voltages V _C11 and V _C12 of FIG.
5), these energies are supplied to the load circuit 11 via the transformer T11. At this time, since the direction of the current flowing through the primary winding n11 is opposite to the direction when the FET Q2 is turned on, an alternating high-frequency voltage is applied to the load circuit 11.

[0044] Thereafter, when the voltage V _C11, V _C12 of the capacitors C11, C12 is zero (time in FIG. 7 t16), diodes D11, D12 connected in parallel with each
Turns on, and the above-described resonance current continues to flow.

Thereafter, when the FET Q1 is turned off (FIG. 7)
At time t17), as shown by the arrow line in FIG. 6, the primary winding n11, the capacitor C11, the capacitor C10, the FET
A current flows through the path of the parasitic diode of Q2 and the primary winding n11, and the energy stored in the transformer T11 is released.

Thereafter, when the release of the energy stored in the transformer T11 is completed (time t18), the operation returns to the circuit operation at time t12 shown in FIG.

High frequency power is supplied to the load circuit 11 by repeating the above circuit operation periodically. That is, when observing the above-mentioned main signal waveforms over one cycle of the AC power supply AC, it becomes as shown in FIG.

[0048] Here, as shown in FIG. 8, when the voltage Vs of the AC power source AC is raised and lowered sinusoidally, the voltage V _C11 of the capacitor C11 is lowered and raised sinusoidally, this voltage V _C11 The voltage V _T11 applied to the primary winding n11 becomes a voltage having a substantially constant fluctuation level (amplitude) by the voltage V _{C12 of the} capacitor C12 which rises and falls likewise when the voltage Vs rises and falls in a sine wave shape. . As a result, the crest factor (amplitude variation rate) of the current I _FL flowing through the secondary load circuit 11 decreases.

As described above, according to the first embodiment, the crest factor of the current flowing through the load circuit 11 can be reduced without increasing the voltage of the capacitor C10.

Since the voltage of the capacitor C12 is superimposed on the voltage of the capacitor C10, the voltage of the capacitor C10 can be set lower. Further, since the voltage of the capacitor C12 resonatesly rises as shown in FIG. 7, the voltage at the time of OFF applied to the FET Q2 is equal to the voltage of the capacitor C10, and the switching loss is reduced by the lower voltage of the capacitor C10. Reduction becomes possible.

Although no filter circuit is provided on the input side in FIG. 1, if a filter circuit for blocking high frequency is provided between the AC power supply AC and the rectifier DB according to a general conventional example, the AC power supply High frequency components can be prevented from being mixed into AC. At this time, if the voltage amplitude of the capacitor C11 is too large, as in FIG.
The polarity is inverted during the period in which the input current is drawn from the device, and a large noise is generated.
Since a pause occurs in the input current and noise is mixed into the AC power supply AC as in the case of FIG. 6C, it is desirable to set the capacitance of the capacitor C11 so that the input current becomes similar to that of FIG. . As a result, it is possible to reduce the harmonics of the input current and to increase the input power factor.

As described above, in the first embodiment, the voltage of the capacitor C10 is lower than that of the conventional configuration while the load circuit 1
Since the crest factor of the current output to 1 can be further reduced and the switching loss can be reduced, the circuit efficiency can be improved and the cost can be reduced.

FIG. 9 is a schematic configuration diagram of a power supply device according to a second embodiment of the present invention. The power supply device according to the second embodiment will be described below. In addition to further including an inductor L1 connected in parallel with
It has the same configuration as the power supply device of the first embodiment.

The transformer T11 of the second embodiment
If the equivalent inductance of the parallel circuit of the secondary side exciting inductance and the inductor L1 is set to be substantially equal to the primary side exciting inductance of the transformer T11 in the first embodiment, the circuit operation of the present power supply device is the same as that of the first embodiment. It is almost the same. Therefore, according to the second embodiment, the same effects as those of the first embodiment can be obtained.

FIG. 10 is a schematic configuration diagram of a power supply device according to a third embodiment of the present invention. The following description of the third embodiment with reference to this drawing shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12, FE
TQ1, Q2, a transformer T11, and a control circuit 10 are provided in the same manner as in the first embodiment. In addition, an inductor L2 connected in series with a secondary winding n12 is further provided, and the load circuit 11 is provided with a secondary winding n12 and an inductor. It is configured to be connected between both ends of L2.

However, the inductor L2 is used instead of the leakage inductance of the transformer T11 in the first embodiment. Accordingly, the circuit operation of the present power supply device is substantially the same as that of the first embodiment, and the same effects as those of the first embodiment can be obtained.

FIG. 11 is a schematic configuration diagram of a power supply device according to a fourth embodiment of the present invention. The power supply device according to the fourth embodiment will be described below with reference to FIG. ~ C12, diodes D11, D12, FE
TQ1, Q2 and a transformer T11 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that the FETs Q1, Q2 are turned on so that at least one of the switching frequency and the on-duty ratio can be changed. And a control circuit 20 for performing on / off control.

Here, the power supply to the load circuit 11 can be adjusted to a desired value by appropriately changing at least one of the switching frequency, the ON period, the duty ratio, and the like for the FETs Q1 and Q2.

For example, when the control circuit 20 performs on / off control so as to shorten the on-time of the FET Q2, the input current Iin drawn from the AC power supply AC can be reduced. In addition, the control circuit 20 controls the FET Q2 during pre-heating or startup when the power consumption of the discharge lamp FL is low.
When the control is performed so as to reduce the ratio of the ON period to one cycle of the above, abnormal increase of the voltage of the capacitor C10 can be suppressed.

As described above, according to the fourth embodiment, advance preheating, starting and lighting control of the discharge lamp can be performed. Also,
Adjustment of the power supplied to the load circuit, that is, dimming lighting of the discharge lamp becomes possible. Further, it is possible to prevent the breakdown of the FET or the like due to the abnormal boosting of the DC voltage due to the fluctuation of the power consumption.

FIG. 12 is a schematic structural view of a power supply device according to a fifth embodiment of the present invention. The following description of the fifth embodiment with reference to FIG. 12 shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12, FE
TQ1, Q2 and a transformer T11 are provided similarly to the first embodiment, and a control circuit 30 different from the first embodiment is provided.

FIGS. 13 to 15 are explanatory diagrams of the operation of the control circuit 30. The control circuit 30 will be described in detail with reference to FIGS. In recent years, there has been a tendency to reduce the diameter of discharge lamps for the purpose of downsizing lighting fixtures, increasing the efficiency of discharge lamps and saving resources, and accordingly, filament coils of discharge lamps have become smaller. It tends to be thinner so that it is sufficiently long within.

In such a discharge lamp, in order to secure the life of the filament coil, that is, the life of the discharge lamp, an upper limit value is defined for the filament current at the time of lighting (see FIG. 13). This upper limit is lower than the lower limit of the filament current at the time of preheating (FIG. 14).
reference). In addition, the thin tube type discharge lamp has a characteristic that a difference between an upper limit value of a no-load secondary voltage for preventing lighting at the time of preheating and a voltage between both ends at the time of dimming lighting is small, and a relatively high lamp impedance. Therefore, when the DC voltage V _{C10 is} the same in both cases, there is little difference in resonance characteristics between when no load is applied and when dimming is performed. As a result, C
In the case of the preheating method, the difference between the operating frequency (switching frequency) at the time of preceding preheating and the time of light control lighting becomes small, and it becomes difficult to make a difference between the filament current at the time of preceding preheating and the time of light control lighting.

Therefore, during dimming lighting, the on-duty ratio of FET Q2 is made smaller than when the value of DC voltage V _C10 is equal as described above, and the ratio of the power supplied to the load to the input power is increased. Then, the DC voltage V _C10 is lowered to light the lamp at a frequency as low as possible. At the time of preheating, the on-duty ratio of the FET Q2 is made larger than when the value of the DC voltage V _C10 is equal as described above, and the ratio of the power supplied to the filament to the input power is made smaller, so that the DC voltage V _Turn on _C10 as high as possible by raising _C10 within the allowable range.

More specifically, in the case of the dimming lighting, as shown in FIG. 13, the lighting which is lit at the frequency fd2 before the on-duty ratio is reduced is reduced to the voltage V _C10 by reducing the on-duty ratio. the lowered lamp current I _FL is equal, the filament current If performing dimming lighting lowered frequency to the upper limit value or less and comprising a frequency fd1 of the time of lighting.

On the other hand, in the case of the preheating, as shown in FIG. 14, the frequency fpre2 is increased before the on-duty ratio is increased.
The DC voltage V _C10 is increased within the allowable range by increasing the on-duty ratio, the filament current If is larger than the lower limit value in the preceding preheating,
The preheating is performed by increasing the frequency to a frequency fpre1 at which the next voltage becomes equal to or lower than the upper limit value.

As described above, by changing the operation of the FETs Q1 and Q2 according to the signal from the control circuit 30 and changing the DC voltage in each operation as shown in FIG. 15, even if the discharge lamp is of a thin tube type, The discharge lamp can be turned on while satisfying the preheating condition by the C preheating method.

FIG. 16 is a schematic structural view of a power supply device according to a sixth embodiment of the present invention. The power supply device according to the sixth embodiment will be described below with reference to FIG. ~ C12, diodes D11, D12, FE
TQ1 and Q2 and the control circuit 10 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that the control circuit 10 is connected between the positive output terminal of the rectifier DB and the connection point of the FETs Q1 and Q2. Primary winding n21
Transformer T21 having next windings n22, n23, n24
It has.

The secondary winding n of the transformer T21
22 is connected to a parallel circuit of a capacitor C211 and the discharge lamp FL, and a secondary winding n23 is connected in series with the capacitor C212 at both ends of one filament of the discharge lamp FL. Next winding n24
Is connected in series with the capacitor C213 at both ends of the other filament of the discharge lamp FL. In FIG. 16, the load circuit 21 includes capacitors C211 to C213 and a discharge lamp FL.

As described above, in the sixth embodiment, one filament of the discharge lamp FL is preheated by the resonance circuit including the capacitor C212 and the secondary winding n23, and the capacitor C213 and the secondary winding n2.
The other filament is preheated by the resonant circuit 4. As a result, the main resonance circuit and the resonance circuit for filament preheating can be designed independently, so that, for example, even if the discharge lamp is a thin tube type, the optimum preheating setting can be performed, and the discharge lamp can be suitably turned on. Can be done.

FIG. 17 is a schematic configuration diagram of a power supply device according to a seventh embodiment of the present invention. The following description of the seventh embodiment with reference to this drawing shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12, FE
TQ1 and Q2, a transformer T11 and a control circuit 10 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that a capacitor C13 having one end connected to the drain of the FET Q1 and a capacitor C13 Primary winding n connected between the other end and the source of FET Q1
31 and a transformer T31 having secondary windings n32 and n33.

The secondary winding n of the transformer T31
Numeral 32 is connected in series with a capacitor C212 at both ends of one filament of the discharge lamp FL, and a secondary winding n33 is connected in series with a capacitor C213 at both ends of the other filament of the discharge lamp FL. That is, the capacitor C, which is a resonance circuit for filament preheating,
13, a series circuit of the primary winding n31 is connected in parallel with the FET Q1, a resonance circuit for filament preheating is connected in parallel to both ends of each filament, and a filament preheating current of the discharge lamp FL is supplied from the secondary windings n32 and n33. It is configured to be taken out. In FIG. 17, the load circuit 21 is configured by the capacitors C211 to C213 and the discharge lamp FL, as in FIG.

As described above, in the seventh embodiment, in the discharge lamp FL, one filament is preheated by the resonance circuit including the capacitor C212 and the secondary winding n32, and the capacitor C213 and the secondary winding n3.
The other filament is preheated by the resonant circuit consisting of 3. As a result, the main resonance circuit and the resonance circuit for filament preheating can be designed independently, so that, for example, even if the discharge lamp is a thin tube type, the optimum preheating setting can be performed, and the discharge lamp can be suitably turned on. Can be done. Further, since the FET Q1 is clamped by the parasitic diode and the diode D12, the voltage across the FET Q1 is a rectangular wave whose amplitude is equal to the DC voltage V _C10 . By configuring a resonance circuit for filament preheating using the voltage of the FET Q1, a preheating current with a small crest factor can be supplied.

FIG. 18 is a schematic structural view of a power supply device according to an eighth embodiment of the present invention. The power supply device according to the eighth embodiment will be described below with reference to FIG. ~ C12, diodes D11, D12, FE
TQ1, Q2, a transformer T11, and a control circuit 10 are provided in the same manner as in the first embodiment, and a difference from the first embodiment is that a primary winding n41 connected in series with a secondary winding n12 is provided. In addition, a transformer T41 having secondary windings n42 and n43 is provided.

The secondary winding n of the transformer T41
41 is connected in series with a capacitor C212 at both ends of one filament of the discharge lamp FL, and a secondary winding n43 is connected in series with a capacitor C213 at both ends of the other filament of the discharge lamp FL. In addition,
In FIG. 18, similarly to FIG.
213 and the discharge lamp FL constitute a load circuit 21.

As described above, in the eighth embodiment, one filament of the discharge lamp FL is preheated by the resonance circuit including the capacitor C212 and the secondary winding n41, and the capacitor C213 and the secondary winding n4.
The other filament is preheated by the resonant circuit consisting of 3. As a result, the main resonance circuit and the resonance circuit for filament preheating can be designed independently, so that, for example, even if the discharge lamp is a thin tube type, the optimum preheating setting can be performed, and the discharge lamp can be suitably turned on. Can be done.

FIG. 19 is a diagram showing an example in which the power supply device according to the first embodiment is applied to another load circuit.
Reference numeral 1 denotes a capacitor C211 connected in parallel with the primary winding n12 of the transformer T11, a discharge lamp FL having a pair of filaments connected to both ends of the capacitor C211 and one end thereof, and the other end of the pair of filaments. And a capacitor C111 connected therebetween.

In FIG. 19, since the capacitor C211 is provided, the degree of freedom in designing the filament current is improved.
For example, a simple design for a thin tube type discharge lamp becomes possible. Further, since the capacitor C211 is connected to the power supply device side with respect to the discharge lamp FL, it is possible to prevent generation of a spike-like high voltage caused by energy accumulated in the transformer T11 when the discharge lamp FL is attached / detached.

FIG. 20 is a schematic configuration diagram of a power supply device according to a ninth embodiment of the present invention. The ninth embodiment will be described below with reference to this figure. This power supply device includes a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12, FE
TQ1, Q2 and a transformer T11 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that various on / off controls are performed on the FETs Q1, Q2. AC voltage Vs at rated lighting
Is varied, the control circuit 40 performs on / off control while changing the on-duty ratio appropriately while keeping the switching frequency constant so that the load current falls within the allowable range. However, it is assumed that the rated voltage of the AC voltage Vs is 100V.

FIG. 21 is a diagram showing, at the top and bottom, the characteristics of the on-duty ratio of FET Q2 with respect to the load current and the characteristics of the on-duty ratio of FET Q2 with respect to the switching frequency. Control circuit 40 will be described in further detail with reference to FIG. .

With the switching frequency kept constant, the input power
50% on-duty ratio of FET Q2
Larger, the power supplied to the load circuit 11 is lower.
However, since the input current increases, the DC voltage V_C10Is
To rise. On duty ratio is slightly larger than 50%
By the way, DC voltage V_C10Load current I due to the rise of _FL
Increases and the on-duty ratio
Load current I_FLThe peak of
Deviates from 50% to the larger one. Use this property
When the power supply voltage Vs decreases, the on-duty
If the ratio is d2 greater than 50%, the load current I_FLBut
It will be within the acceptable range.

In the resonance circuit, the resonance frequency f0
, The reactive current component decreases and the circuit efficiency improves, so as shown in FIG. 21, the switching frequency is kept constant even when the power supply voltage Vs fluctuates, and the on-duty ratio of the FET Q2 that draws the input current is d1, d2, d3
Is controlled so that the load current I _FL falls within the allowable range.

As described above, according to the ninth embodiment, the FET Q2 that draws the input current in accordance with the voltage fluctuation of the AC power supply Vs
By controlling the on-duty ratio of the
Even when the voltage Vs of C fluctuates, it becomes possible to keep the load current I _FL within the allowable range.

FIG. 22 is a schematic configuration diagram of a power supply device according to a tenth embodiment of the present invention. The following description of the tenth embodiment with reference to this drawing shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12,
In addition to the provision of the FETs Q1, Q2 and the transformer T11 as in the first embodiment, the difference from the first embodiment is that various on / off controls are performed on the FETs Q1, Q2. AC voltage V at rated lighting
When s fluctuates, there is provided a control circuit 50 that performs on / off control while appropriately changing the switching frequency and the on-duty ratio so that the load current falls within the allowable range. I have.

FIG. 23 shows, at the top and bottom, the characteristics of the on-duty ratio of FET Q2 with respect to the load current and the characteristics of the on-duty ratio of FET Q2 with respect to the switching frequency. The control circuit 50 will be described in further detail with reference to FIG. .

In the ninth embodiment, when the power supply voltage Vs fluctuates, the switching frequency is kept constant, and the on-duty ratio of the FET Q2 that draws the input current is d1, d
The control is performed such that the load current falls within the allowable range by changing the values to d2 and d3. At this time, the voltage Vs of the AC power supply AC
Becomes higher, the on-duty ratio becomes smaller and smaller than 50%, and the sinusoidal waveform of the load current is distorted. When the load circuit includes a discharge lamp, there is a problem that high-frequency components resulting from distortion of the load current are radiated as noise.

Therefore, in the tenth embodiment, as shown in FIG. 23, the on-duty ratio Vs becomes too small.
At 100 V, the switching frequency is increased to make the on-duty ratio as close to 50% as possible, and control is performed so as to reduce high frequency components caused by load current distortion. For example, when Vs is 110 V, on / off control is performed by setting the on-duty ratio to d3 'higher than d3 and increasing the switching frequency. in short,
Control is performed to appropriately set the switching frequency and on-duty ratio at each AC power supply voltage so that the circuit efficiency and the harmonic component of the load current trade off.

As described above, according to the tenth embodiment, the FET Q that draws the input current according to the voltage fluctuation of the AC power supply Vs
2 by appropriately changing and controlling the switching frequency and the on-duty ratio, it is possible to keep the load current within the allowable range even when the voltage Vs of the AC power supply AC fluctuates, and to radiate from the discharge lamp. Noise can be reduced.

FIG. 24 is a schematic configuration diagram of a power supply device according to an eleventh embodiment of the present invention. The following description of the eleventh embodiment with reference to this drawing shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12,
In addition to the provision of the FETs Q1, Q2 and the transformer T11 as in the first embodiment, the difference from the first embodiment is that various on / off controls are performed on the FETs Q1, Q2. AC voltage V at rated lighting
When s fluctuates, while the switching frequency and the on-duty ratio are appropriately changed mainly based on the on-duty ratio, on / off control is performed, while the load circuit 11 is driven at an output lower than the rated output, When the voltage Vs fluctuates, the switching frequency and the on-duty ratio are appropriately changed mainly with the switching frequency.
A control circuit 60 for performing on / off control is provided.

FIG. 25 is a diagram showing the characteristics of the on-duty ratio of the FET Q2 with respect to the load current and the characteristics of the on-duty ratio of the FET Q2 with respect to the switching frequency, respectively. .

In the ninth embodiment, when the power supply voltage Vs fluctuates, the switching frequency is kept constant and the on-duty ratio of the FET Q2 that draws the input current is set to d1, d.
The control is performed such that the load current falls within the allowable range by changing the values to d2 and d3. At this time, if the present power supply device is configured so that the discharge lamp FL of the load circuit 11 can be dimmed and lit, on / off control is performed with a small on-duty ratio in order to suppress the DC voltage V _C10 from increasing during dimming and lighting. So
When the output is reduced, the distortion of the load current waveform increases.

Therefore, in the eleventh embodiment, as shown in FIG. 25, when the AC voltage Vs fluctuates during dimming lighting,
The on-duty ratio and the switching frequency are appropriately changed mainly based on the switching frequency in accordance with the voltage Vs of the AC power supply AC so that the on-duty ratio takes as large a value as possible and does not change much. Control for reducing the wave component is performed. For example,
When the voltage Vs is 100 V, the on-duty ratio is set to d1
Increase d1 'to increase the switching frequency,
When the voltage Vs is 110 V, control is performed to increase the switching frequency by setting the on-duty ratio to d3 'larger than d3.

However, when the C preheating method is used for the thin tube type discharge lamp FL, if the switching frequency is increased too high, the preheating current of the filament may increase and the preheating condition may not be satisfied. Control for adjusting the switching frequency is performed within a range that satisfies the condition (a range equal to or less than the “upper limit of switching frequency” in FIG. 25). As a result, the AC power supply V
When the voltage of s fluctuates, the load current is kept within an allowable range, and harmonic components of the load current can be reduced.

As described above, according to the eleventh embodiment, the FET Q that draws in the input current according to the voltage fluctuation of the AC power supply Vs
2 by appropriately changing and controlling the switching frequency and the on-duty ratio, it is possible to keep the load current within the allowable range even when the voltage Vs of the AC power supply AC fluctuates, and to radiate from the discharge lamp. Noise can be reduced.

FIG. 26 is a schematic configuration diagram of a power supply device according to a twelfth embodiment of the present invention. The following description of the twelfth embodiment will be made with reference to FIG. ~ C12, diodes D11, D12,
FETs Q1 and Q2 and a transformer T11 are provided in the same manner as in the first embodiment. What is different from the first embodiment is that a voltage detection circuit 12 for detecting a voltage between both ends of a capacitor C10 and a detection of the voltage detection circuit 12 A control circuit 70 is provided for performing on / off control including stopping the FETs Q1 and Q2 while appropriately changing the switching frequency, the ON period, the duty ratio, and the like according to the result.

For example, the switching frequency and the switching frequency are set so that the voltage value detected by the voltage detection circuit 12 becomes a predetermined value.
While appropriately changing the ON period and the duty ratio, F
On / off control for ETQ1 and Q2 is performed. Thereby, the capacitor C10 can hold the constant voltage of the predetermined value. As a result, when stable output characteristics are obtained and the load circuit includes a discharge lamp,
It is possible to suppress flickering of lighting.

When the voltage value detected by the voltage detection circuit 12 becomes higher than the level considered abnormal, the FET
Control for stopping the switching operation of Q1 and Q2 is performed.
Thus, it is possible to prevent the destruction of the circuit element due to the overvoltage.

FIG. 27 is a schematic configuration diagram of a power supply device according to a thirteenth embodiment of the present invention. The following description of the thirteenth embodiment with reference to FIG. 27 shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12,
FET Q1, Q2, transformer T11 and control circuit 10
In addition to the comprises like the first embodiment, as the difference from the first embodiment further includes a capacitor C _P1 is connected in parallel with FET Q2.

FIG. 28 to FIG. 32 are explanatory diagrams of the operation of the present power supply device, and FIG. 33 is a signal waveform diagram of each part during operation of the present power supply device. The operation of the thirteenth embodiment will be described with reference to these drawings. .

In the steady state after the charging of the capacitor C10, at the time t22 shown in FIG. 33, as shown by the arrow line in FIG.
1, primary winding n11, FET Q2 and capacitor C1
0, the current _IT11 flows through the path C0, the capacitor C10 serves as a power source, the capacitor C11 is charged, the voltage V _C11 increases, and the load circuit 11
Is supplied with power. At this time, current I _T11 does not flow through the capacitor C _P1.

Thereafter, the voltage V _C11 of the capacitor _C11 is equal to the voltage V _{C10 of the} capacitor _C10 and the output voltage of the rectifier DB.
When the voltage rises to the difference voltage (V _C10 − | Vs |) with respect to | Vs | (time t23 in FIG. 33), as shown by the arrow line in FIG. 29, the AC power supply AC, the rectifier DB, the primary winding n11, and the FET Q
2. Current I _{T11 in} the path of rectifier DB and AC power supply AC
Flows, and the input current Iin
Is drawn.

Thereafter, when the FET Q2 is turned off (FIG.
3 at time t24), as shown in FIG.
Due to the energy stored in 1, the current I _CP1 for charging the capacitor C _P1 flows, and the voltage V _Q2 across the FET _Q2 rises gently, while the current I _Q2 flowing through the FET _Q2 instantaneously goes to zero. Thereby, the switching loss of the FET Q2 is greatly reduced.

When the voltage V _Q1 becomes zero, as shown in FIG. 30, the transformer T11 storing energy by the current flowing through the primary winding n11 and the AC power supply AC become the power supply, and the AC power supply AC and the rectifier DB, primary winding n1
1, a parasitic diode of the FET Q1, a capacitor C12,
Capacitor C10, current I _T11 flows in the path of the rectifier DB and the AC power source AC, while pulling the input current Iin capacitor C10, C12 is charged. At this time, as shown in FIG. 33, the voltage V _{C12 of the} capacitor C12 increases due to the resonance effect with the leakage inductance of the transformer T11. Further, the FET Q1 is turned on.

When the FET Q1 is turned on, the transformer T1
1 and the capacitors C11 and C1
2 and C111, the capacitors C11, C12, and FE as shown by the arrow in FIG.
A resonance current flows through the path of TQ1, primary winding n11 and capacitor C11. Thereafter, the capacitors C11 and C1
The voltages V _C11 and V _C12 of FIG.
25), these energies are supplied to the load circuit 11 via the transformer T11. At this time, the primary winding n11
The direction of the current flowing through the load circuit 11 is opposite to that when the FET Q2 is turned on, so that an alternating high-frequency voltage is applied to the load circuit 11.

Thereafter, when the voltages V _C11 and V _{C12 of the} capacitors C11 and C12 become 0 (time t26 in FIG. 33),
Diodes D11 and D1 connected in parallel to each other
2 turns on and the above-mentioned resonance current continues to flow.

Thereafter, when the FET Q1 is turned off (FIG. 3)
3 at time t27), as shown in FIG.
Due to the energy stored in 1, the current I _CP1 for charging the capacitor C _P1 flows, and the voltage V _Q1 across the FET _Q1 rises gently, while the current I _Q1 flowing through the FET _Q1 instantaneously goes to zero. Thereby, the switching loss of the FET Q1 is greatly reduced.

When the voltage V _Q2 becomes zero, as shown in FIG. 32, the primary winding n11, the capacitor C11, the capacitor C10, the parasitic diode of the FET Q2 and the primary winding n
A current flows through the path of No. 11, and the energy stored in the transformer T11 is released.

Thereafter, when the release of the energy stored in the transformer T11 is completed (time t28), the operation returns to the circuit operation at time t22 shown in FIG.

As described above, according to the thirteenth embodiment, the crest factor of the current flowing through the load circuit 11 can be reduced without increasing the voltage of the capacitor C10. By reducing the voltage rise, switching loss can be reduced.

FIG. 34 is a schematic configuration diagram of a power supply device according to a fourteenth embodiment of the present invention. The following description of the fourteenth embodiment with reference to FIG. 34 shows that this power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12,
FET Q1, Q2, transformer T11 and control circuit 10
In the same manner as in the first embodiment, and further includes a capacitor _CP2 as a difference from the first embodiment.

One end of the capacitor C _P2 is connected to the FET Q2.
And the other end is connected to the source side of the FET Q2 via the capacitor C10. That is, in terms of high frequency, the capacitor C _P2 is an FET
This is equivalent to being connected in parallel with Q2. Therefore, according to the fourteenth embodiment, similar to the thirteenth embodiment,
Switching loss can be reduced.

FIG. 35 is a schematic configuration diagram of a power supply device according to a fifteenth embodiment of the present invention. The following description of the fifteenth embodiment with reference to FIG. 35 shows that the power supply device has a rectifier DB and a capacitor C10. ~ C12, diodes D11, D12,
FET Q1, Q2, transformer T11 and control circuit 10
In addition to the comprises like the first embodiment, as a difference from the first embodiment further includes a capacitor C _P3 connected in parallel with the FET Q1. However, capacitor C _P3
Is smaller than the capacitors C11 and C12. As a result, the circuit operation is substantially the same as that of the thirteenth embodiment, so that the switching loss can be reduced.

FIG. 36 is a schematic configuration diagram of a control circuit of a power supply device according to a sixteenth embodiment of the present invention, and FIG. 37 is an explanatory diagram of the operation of the control circuit. Give an explanation.

This power supply device comprises a rectifier DB, a capacitor C
10 to C12, diodes D11 and D12, FETQ
1, Q2 and a transformer T11 are provided in the same manner as in the first embodiment. The difference from the first embodiment is that the switching frequency and the on A control circuit 80 is provided for performing on / off control of the FETs Q1 and Q2 while appropriately changing the period and the duty ratio.

As shown in FIG. 36, the control circuit 80 includes an astable multivibrator 301 such as a μPD5555C and a capacitor C for determining the oscillation frequency.
b1 and the variable resistor Rb1, for example, μPD5555C
, A capacitor Cb2 and a resistor Rb2 that determine the High period of the output pulse, and a driver that turns on the FET Q1 and turns off the FET Q2 when the output pulse Vb1 of the monostable multivibrator 302 is High, for example. 303.

Next, an outline of the circuit operation by the control circuit 80 will be described. At the time of rated lighting, the FETs Q1 and Q2
They are turned on / off alternately as shown in FIG. When shifting from this rated lighting to dimming lighting, the discharge lamp FL
37, the FETs Q1 and Q2
As shown in (b), the output is alternately turned on / off with an output pulse having a higher switching frequency. At this time, if the off period of the FET Q2 is kept constant, the voltage V
_Q2 is reduced to be substantially equal to the voltage V _C10 of the capacitor C10, as a result, it is possible to reduce the switching losses.

FIG. 38 is a schematic configuration diagram of a power supply device according to a seventeenth embodiment of the present invention, and FIG. 39 is an explanatory diagram of the operation of a control circuit of the power supply device. Give an explanation.

As shown in FIG. 38, this power supply device comprises a rectifier DB, capacitors C10 to C12, and a diode D1.
1, D12, FETs Q1, Q2, and a transformer T11 as in the first embodiment, and is different from the first embodiment in that it comprises a series circuit of resistors R11 and R12 connected in parallel with a capacitor C10. A detection circuit 22 that outputs the voltage between both ends of the capacitor C10 as a voltage V1 from a connection point of the series circuit and a series circuit of resistors R21 and R22 connected in parallel with the FET Q2. A detection circuit 23 that outputs a source voltage as a voltage V2 and an FET Q in accordance with both output signals from the detection circuits 22 and 23 to adjust power supplied to the load circuit 11 so that dimming and lighting can be performed.
1 and a control circuit 90 for performing on / off control of Q2.

However, resistors R11, R12, R21, R
22 is (R12 / (R11 + R12))> (R22 /
(R21 + R22)).

The control circuit 90 includes a comparator 401 for receiving the voltages V1 and V2 at the non-inverting input terminal and the inverting input terminal, a resistor R3 connected between the output terminal of the comparator 401 and the voltage Vcc line, Oscillator 402 with variable frequency and duty ratio
And both outputs V of the comparator 401 and the oscillator 402
3, an AND circuit 403 for ANDing V4, and a driver circuit 404 for turning on / off the FETs Q1 and Q2 according to the output V5 of the AND circuit 403.

Next, an outline of the circuit operation by the control circuit 90 will be described. At the time of rated lighting, the FETs Q1 and Q2
They are turned on / off alternately as shown in FIG. When shifting from this rated lighting to dimming lighting, the discharge lamp FL
FETs Q1 and Q2 are connected as shown in FIG.
As shown in (b), the switching is alternately turned on / off by the operation of the switching frequency changed to a higher value. At this time, the output V3 of the comparator 401 becomes High if the voltage V1 is higher than the voltage V2, and becomes Low if the voltage V1 is lower than the voltage V2. On the other hand, the output of the oscillator 402 is changed so that the ON periods of the FETs Q1 and Q2 are unbalanced. Then, the AND result V5 of these outputs V3 and V4 becomes an input signal of the driver circuit 404, and even if the switching frequency of the FETs Q1 and Q2 increases, the voltage V _C10 and the voltage V _Q2 are substantially equal and the transmitter 402 Is high, the FET Q2 is turned on. Therefore, similarly to the sixteenth embodiment, it is possible to prevent an increase in switching loss.

FIG. 40 is a diagram showing an application example of the power supply device according to the first embodiment to another load circuit.
Reference numeral 1 denotes a capacitor C211 connected in parallel with the primary winding n12 of the transformer T11, a discharge lamp FL having a pair of filaments connected to both ends of the capacitor C211 and one end thereof, and the other end of the pair of filaments. It comprises a preheating / resonance capacitor C111 connected therebetween, and an inductor L3 interposed in one of both connection lines of the capacitor C211 and the discharge lamp FL.

Here, assuming that the high-frequency vibration of the transformer T11 is a high-frequency vibration source HF and the leakage inductance of the transformer T11 viewed from the secondary winding n12 side is L, the circuit shown in FIG. 40 is equivalent to the equivalent circuit shown in FIG. Can be replaced by

This equivalent circuit includes an inductance L, an inductor L3, and capacitors C111 and C21.
1 and two resonance frequencies f
Since it has 01 and f02, its frequency characteristics are as shown in FIG. However, f03 shown in FIG.
3 and the anti-resonance frequency given by the following (Equation 1) using the values of the capacitor C111.

[0125]

(Equation 1)

When the load is light, the voltage Vz across the load and the filament current If have peak values at the resonance frequencies f01 and f02, and dips at the antiresonance frequency f03 between the resonance frequencies f01 and f02.

The lighting and dimming of the discharge lamp FL are performed in a frequency region f1 where an output can be obtained near the resonance frequency f01. On the other hand, the preheating is performed at a frequency fpre near the resonance frequency f02 at which a proper preheating current and a no-load secondary voltage low enough not to start discharging can be secured.

When the discharge lamp FL is of a thin tube type, it is necessary to set the capacity of the capacitor C111 small at the time of lighting in order to reduce the preheating current. On the other hand, at the time of preheating, it is necessary to increase the preheating current. At this time, FIG.
At 0, a larger preheating current can flow through the second peak of the resonance. However, to set the relationship between the no-load secondary voltage during pre-heating and the pre-heating current,
Inductance L, inductor L3 and capacitor C
It is sufficient to adjust the constants of 111 and C211. If these constants are adjusted, the frequency interval between the resonance frequencies f01 and f02 changes and the resonance curve changes.

As described above, according to the configuration of FIG. 40, the presence of two resonance points and one anti-resonance point in the load resonance circuit makes it possible to satisfy the preheating condition even if the discharge lamp is a thin tube type. Thus, the thin tube discharge lamp can be optimally lit.

In FIG. 40, the transformer T11 is a leakage transformer. However, the present invention is not limited to this, and it is needless to say that an inductor corresponding to the leakage may be connected to the secondary side of the transformer having no leakage. No.

FIG. 43 is a schematic configuration diagram of a power supply device according to the eighteenth embodiment of the present invention. The following description of the eighteenth embodiment with reference to FIG.
The configuration is the same as that of the power supply circuit of the first embodiment except that it further includes a clamp circuit 14 connected in parallel with the power supply circuit 2.

The clamp circuit 14 has a high impedance when the circuit is operating normally, and hardly affects the circuit operation. On the other hand, load circuit 1
1 when the voltage of the capacitor C12 which is performing voltage resonance operation suddenly rises, for example, when the impedance of the capacitor 1 suddenly changes, for example, when the discharge lamp FL is attached or detached, or when the discharge lamp Emiless, etc. Clamped by value. As a result, application of an overvoltage to the circuit element is prevented, and destruction of the circuit element can be prevented.

FIG. 44 is a schematic configuration diagram of a power supply device according to the nineteenth embodiment of the present invention. The following description of the nineteenth embodiment with reference to FIG. 44 shows that the power supply device is connected in parallel with the FET Q2. The configuration is the same as the power supply circuit of the first embodiment except that the power supply circuit further includes a clamp circuit 24.

In the nineteenth embodiment as well, similarly to the eighteenth embodiment, the voltage of the capacitor C12 performing a voltage resonance operation suddenly rises at the time of abnormality such as a sudden change in the impedance of the load circuit 11. At this time, the application of the overvoltage to the circuit element is prevented by the clamp of a predetermined voltage value, and the destruction of the circuit element can be prevented.

FIG. 45 is a schematic configuration diagram of a power supply device according to a twentieth embodiment of the present invention. The following description of the twentieth embodiment will be made with reference to FIG.
The configuration is the same as that of the power supply circuit of the first embodiment except that the power supply circuit further includes a clamp circuit 34 connected in parallel with the power supply circuit 2.

Also in the twentieth embodiment, similarly to the eighteenth embodiment, the voltage of the capacitor C12 performing a voltage resonance operation suddenly rises at the time of abnormality such as a sudden change in the impedance of the load circuit 11. At this time, the application of the overvoltage to the circuit element is prevented by the clamp of a predetermined voltage value, and the destruction of the circuit element can be prevented.

FIG. 46 is a schematic configuration diagram of a power supply device according to a twenty-first embodiment of the present invention. The following description of the twenty-first embodiment with reference to FIG.
The configuration is the same as that of the power supply circuit of the first embodiment, except that the power supply circuit of the first embodiment is further provided with a clamp circuit 44 connected between the connection point of the FETs 1 and 12 and the connection point of the FETs Q1 and Q2.

Also in the twenty-first embodiment, similarly to the eighteenth embodiment, the voltage of the capacitor C12 which performs a voltage resonance operation when the impedance of the load circuit 11 suddenly changes is rapidly increased. At this time, the application of the overvoltage to the circuit element is prevented by the clamp of a predetermined voltage value, and the destruction of the circuit element can be prevented.

FIG. 47 is a schematic configuration diagram of a power supply device according to the twenty-second embodiment of the present invention. The power supply device according to the twenty-second embodiment will be described below with reference to FIG.
The configuration is the same as that of the power supply circuit of the twelfth embodiment except that the power supply circuit further includes a clamp circuit 54 connected in parallel with the power supply circuit 2.

The clamp circuit 54 includes a diode 540 connected to the drain and anode of the FET Q1, a capacitor C540 connected between the cathode of the diode 540 and the source of the FET Q2, and a resistor R540 connected in parallel with the capacitor C540. It consists of.

[0141] When the circuit is operating normally, the capacitor C540, approximately the peak voltage of the sum of the voltage V _C10 of the voltage V _C12 and the capacitor C10 of the capacitor C12 is applied.

On the other hand, when the voltage of the capacitor C12 performing voltage resonance operation suddenly rises in an abnormal state such as a sudden change in the impedance of the load circuit 11, the diode D540 turns on and the capacitor C540 turns on.
Is charged, rapid rise of the voltage is suppressed, and application of overvoltage to the circuit element is prevented. Thereby, for example, the voltage rise of the capacitor C12 is detected and the FET Q
1, Q2 can be controlled to protect the circuit so that excessive stress is not applied to the circuit element.

It is to be noted that the capacitor C5 is used to prevent the circuit element from being destroyed by an excessive voltage which is instantaneously generated at the time of abnormality.
Choose 40 capacities. The resistor R540 adjusts the discharge amount of the capacitor C540 so that the peak voltage is held in the capacitor C540 in a normal state, and the voltage held in the capacitor C540 is suppressed to a voltage that prevents the destruction of circuit elements in an abnormal state.

In the twenty-second embodiment, similarly to the eighteenth embodiment, application of an overvoltage to the circuit element can be prevented in the event of an abnormality such as a sudden change in the impedance of the load circuit 11, and the destruction of the circuit element can be prevented. Prevention becomes possible.

FIG. 48 is a schematic configuration diagram of a power supply device according to a twenty-third embodiment of the present invention. The twenty-third embodiment will be described below with reference to FIG.

This power supply device comprises a diode 640 connected between the connection point of FETs Q1 and Q2 and the anode, a capacitor C640 connected between the cathode of diode 540 and the connection point of capacitors C11 and C12, and a capacitor C640 It is configured similarly to the power supply circuit of the twelfth embodiment except that it further includes a clamp circuit 64 including a resistor R640 connected in parallel with the power supply circuit.

In the twenty-third embodiment, similarly to the twenty-second embodiment, the voltage of the capacitor C12 which performs voltage resonance operation suddenly rises in an abnormal state such as when the impedance of the load circuit 11 suddenly changes. At this time, the application of the overvoltage to the circuit element is prevented by the clamp of a predetermined voltage value, and the destruction of the circuit element can be prevented.

FIG. 49 is a schematic configuration diagram of a power supply device according to a twenty-fourth embodiment of the present invention. The power supply device according to the twenty-fourth embodiment will be described below with reference to FIG.
The configuration is the same as that of the power supply circuit of the first embodiment except that it further includes a clamp circuit 74 connected in parallel with the power supply circuit 2.

The clamp circuit 74 is a circuit protection element that has a high impedance below a certain predetermined voltage, changes impedance when the predetermined voltage is reached, and does not apply more than that voltage. FIG. 49 shows an example of ZNR. I have.

In the twenty-fourth embodiment, similarly to the eighteenth embodiment, in the event of an abnormality such as a sudden change in the impedance of the load circuit 11, the application of an overvoltage to a circuit element can be prevented by clamping a predetermined voltage value. It is possible to prevent the destruction of the circuit element.

In the various embodiments described above, the configuration is such that the capacitor C11 is connected in parallel to the diode D11. However, the present invention is not limited to this configuration, and as shown in FIG.
A configuration in which a capacitor C21 is connected between both output terminals of the rectifier DB may be used. For example, a rectifier DB for rectifying AC power from an AC power supply AC into DC power, a diode D11 (first diode) having a positive output terminal of the rectifier DB and an anode connected in the forward direction, and a diode D1
A smoothing capacitor C10 connected between the cathode of the first rectifier DB and the negative output terminal of the rectifier DB;
A diode D12 (second diode) having an anode connected to the cathode of the first D1 and a second diode D12;
FETs Q1 and Q2 (a pair of switching elements) connected in series between the cathode of the rectifier DB and the negative output terminal of the rectifier DB, a control circuit 10 for performing on / off control of the FETs Q1 and Q2, and connection of the FETs Q1 and Q2. Primary winding n1 connected between the point and the positive output terminal of the rectifier DB
1, a transformer T11 having a secondary winding n12 connected to the load circuit 11, a capacitor C21 (first capacitor) connected between both output terminals of the rectifier DB, and a capacitor connected in parallel with the diode D12. A configuration including C12 (second capacitor) may be used.
In this configuration, as shown in FIG.
The voltage V _C21 becomes the voltage waveform is clamped by the voltage of the rectified voltage V _C10 and the input voltage Vs of the capacitor C10. Therefore, by the voltage V _C21 and the voltage V _C12 ,
Since a voltage _VT11 as shown in FIG. 51 is applied to the primary winding n11, a voltage having a substantially constant fluctuation level is applied to the transformer T11. As a result, the crest factor of the current I _FL flowing through the secondary-side load circuit 11 decreases, and the same effect as in the first embodiment can be obtained.

In addition to the structure shown in FIG.
As shown in FIG. 1, for example, a rectifier DB for rectifying AC power from an AC power supply AC to DC power, a diode D31 (first diode) having a cathode connected to a negative output terminal of the rectifier DB in a forward direction, This diode D31
And a diode D31 connected between the anode of the rectifier DB and the positive output terminal of the rectifier DB.
D32 (second diode) whose anode is connected to the anode of the diode D32 (second diode), and FETs Q1 and Q2 (a pair of switching elements) connected in series between the anode of the diode D32 and the positive output terminal of the rectifier DB.
A control circuit 10 for performing on / off control of these FETs Q1 and Q2, a connection point of the FETs Q1 and Q2 and a rectifier DB
And a secondary winding n1 connected to the load circuit 11 while being connected between the negative output terminal of
And a diode T31, D3
2 and capacitors C31 and C32 connected in parallel, respectively.
It goes without saying that the same effect as in the first embodiment can be obtained even if the power supply device is configured by the (first and second capacitors).

Further, in each of the above embodiments, the configuration is such that the transformer is used for the load, but it is not always necessary to use the transformer for the load.
FIG. 53 shows an example of this configuration. The power supply shown in this figure
A rectifier DB for full-wave rectification of AC power from the AC power supply AC to DC power, a diode D11 having a positive output terminal connected to the positive output terminal of the rectifier DB, and a cathode of the diode D11 and a negative electrode of the rectifier DB. A smoothing capacitor C10 connected between the negative output terminal of the rectifier DB and a diode D12 whose anode is connected to the cathode of the diode D11 in the forward direction. , A control circuit 10 for performing on / off control of these FETs Q1, Q2, and FETs Q1, Q2.
, And an inductance L2 connected in parallel with the load circuit 11 and the inductance L1 in parallel with the inductance L1.
And capacitors C11 and C12 connected in parallel with the diodes D11 and D12, respectively. Even in such a configuration, the voltage generated in the capacitors C11 and C12 makes the peak value of the voltage applied to the inductance L1 substantially constant, and the peak factor of the current flowing through the load circuit 11 decreases. As a result, the loss of the FETs Q1 and Q2 can be reduced. Incidentally, the connection example of FIG. 53 is an example, and the transformer T11 of each of the above embodiments is connected to the inductance L1,
The same effect as that of the embodiment can be obtained with the configuration in place of L2.

[0154]

As is apparent from the above description, according to the first aspect of the present invention, a rectifier for rectifying AC power to DC power has one end connected to one output terminal of the rectifier in a forward direction. A first diode, a smoothing capacitor connected between the other end of the first diode and the other output terminal of the rectifier, and a second diode connected to the other end of the first diode in the forward direction. A diode, a pair of switching elements connected in series between the other end of the second diode and the other output terminal of the rectifier, and a diode connected in anti-parallel with each of the pair of switching elements;
A transformer having a primary winding connected between a connection point of the pair of switching elements and one output terminal of the rectifier and having a secondary winding connected to a load circuit; Since the two diodes and the first and second capacitors respectively connected in parallel are provided, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

According to the second aspect of the invention, a rectifier for rectifying AC power to DC power, a first diode having one end connected to one output terminal of the rectifier in the forward direction, A smoothing capacitor connected between the other end and the other output terminal of the rectifier, a second diode having one end connected to the other end of the first diode in a forward direction, and a second end of the second diode. A pair of switching elements connected in series between the other output terminal of the rectifier, a diode connected in anti-parallel with each of the pair of switching elements, and a connection point of the pair of switching elements and one of the rectifiers Connected to the output terminal of
A transformer having a secondary winding having a secondary winding and connected to a load circuit, a first capacitor connected between both output terminals of the rectifier, and a second capacitor connected in parallel with the second diode. , The crest factor of the current flowing through the load circuit can be reduced and the loss of the switching element can be reduced.

According to the third aspect of the present invention, since the first inductor is provided in parallel with the primary winding, the crest factor of the current flowing through the load circuit and the loss of the switching element can be reduced.

According to the fourth aspect of the present invention, there is provided the second inductor connected in series with the secondary winding, and the load circuit is constituted by a parallel circuit of a load and a capacitor.
Since it is connected between both ends of the secondary winding and the second inductor, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

According to the fifth aspect of the present invention, since the transformer has a leakage inductance component as the second inductor, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

According to the present invention, at least one of a switching frequency and an on-duty ratio can be changed with respect to the pair of switching elements so as to be changeable.
Since the control means for performing the off control is provided, the amount of power supplied to the load circuit can be adjusted. In addition, when the load circuit includes a discharge lamp, control such as preheating, starting, and dimming lighting can be performed. Further, it is possible to prevent the switching element and the like from being destroyed due to abnormal DC voltage boosting due to fluctuations in power consumption.

According to the seventh aspect of the present invention, at least one of a switching frequency and an on-duty ratio is changed in accordance with a voltage change of the AC power to perform on / off control for the pair of switching elements. The control means mainly controls the on-duty ratio when the rated output is being supplied to the load circuit, while mainly controlling the switching frequency when the output to the load circuit is reduced. Since the control is performed, even if the voltage of the AC power fluctuates, the load current can be kept within an allowable range.

According to the invention, the voltage detecting means for detecting the voltage between both ends of the smoothing capacitor and at least one of the switching frequency and the duty ratio can be changed according to the detection result of the voltage detecting means. And control means for performing on / off control on the pair of switching elements, so that when the circuit is operating normally, the detected voltage is controlled to a predetermined level to obtain a stable output to the load circuit. Therefore, when the load circuit includes a discharge lamp, it is possible to suppress flickering of illumination.
In addition, when an abnormality occurs in the circuit, it is possible to prevent the element from being destroyed due to an overvoltage by performing control such as stopping the oscillation by detecting an abnormal increase in the voltage.

According to the ninth aspect of the present invention, since the clamp circuit for limiting the applied voltage to the predetermined voltage is provided, it is possible to prevent the application of the overvoltage to the circuit element and the destruction of the circuit element.

According to the tenth aspect of the present invention, since at least one of the pair of switching elements is provided with at least a capacitor connected in parallel at high frequency, loss of the switching element, improvement of the circuit efficiency, noise and the like can be improved. The cost can be reduced.

According to the eleventh aspect of the present invention, for a switching element connected between both output terminals of the rectifier via the primary winding, the voltage of the switching element and the voltage across the smoothing capacitor are applied. Since the control means for performing the on-control is provided when is substantially equal to each other, it is possible to suppress an increase in loss at the time of switch-on.

According to the twelfth aspect of the present invention, voltage detecting means for detecting a voltage across a switching element connected between both output terminals of the rectifier via the primary winding,
Since there is provided control means for performing on / off control of the pair of switching elements using the detection result of the voltage detection means, it is possible to suppress an increase in loss at the time of switch-on.

According to the thirteenth aspect, the load circuit has at least two resonance frequencies and at least one resonance frequency.
Since it has two anti-resonance frequencies, it is possible to reduce the crest factor of the current flowing through the load circuit and reduce the loss of the switching element.

According to the fourteenth aspect of the present invention, the load circuit includes a third capacitor connected to both ends of the secondary winding via a second inductor, and the third capacitor connected via a third inductor. And a fourth capacitor connected between the other ends of the pair of filaments. For example, when the load circuit includes a capillary discharge lamp, Optimum preheating control becomes possible, and suitable starting and lighting become possible.

According to the present invention, since the transformer has a leakage inductance component as the second inductor, for example, when the load circuit includes a thin tube type discharge lamp, optimal preheating control becomes possible. , Suitable starting and lighting are enabled.

According to the sixteenth aspect of the present invention, there is provided control means, wherein the load circuit includes a discharge lamp, and the control means, when dimming and lighting the discharge lamp, controls the DC voltage of the smoothing capacitor. When controlling at least one of the switching frequency and the duty ratio of the pair of switching elements so as to be a value lower than the rated lighting, when preheating the filament of the discharge lamp,
Since at least one of the switching frequency and the duty ratio of the pair of switching elements is controlled so that the DC voltage of the smoothing capacitor becomes a higher value than during rated lighting, for example, when the load circuit includes a capillary discharge lamp, Optimum preheating control becomes possible, and suitable starting and lighting become possible.

According to the present invention, the load circuit has a capacitor connected to both ends of the secondary winding and a pair of filaments each connected to one end of the capacitor at both ends. Since a resonance circuit for preheating is connected between both ends of each of the filaments, for example, when the load circuit includes a discharge lamp of a thin tube type, optimal preheating control becomes possible, and suitable starting and lighting are performed. Becomes possible.

According to the eighteenth aspect of the present invention, a rectifier for rectifying AC power to DC power, a first diode having one end connected to one output terminal of the rectifier in a forward direction,
A smoothing capacitor connected between the other end of the first diode and the other output terminal of the rectifier; a second diode connected to the other end of the first diode in a forward direction; A pair of switching elements connected in series between the other end of the diode and the other output terminal of the rectifier; a diode connected in anti-parallel with each of the pair of switching elements; and a connection point of the pair of switching elements. A first inductance connected between the first rectifier and one output terminal of the rectifier; a second inductance connected in parallel with the first inductance together with a load circuit;
Since the first and second diodes are provided with the first and second capacitors respectively connected in parallel, the crest factor of the current flowing through the load circuit and the loss of the switching element can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power supply device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the power supply device according to the first embodiment.

FIG. 3 is an explanatory diagram of an operation of the power supply device according to the first embodiment.

FIG. 4 is an operation explanatory diagram of the power supply device according to the first embodiment.

FIG. 5 is an operation explanatory diagram of the power supply device according to the first embodiment.

FIG. 6 is an operation explanatory diagram of the power supply device according to the first embodiment.

FIG. 7 is a signal waveform diagram of each unit when the power supply device according to the first embodiment operates.

FIG. 8 is a signal waveform diagram of each unit when the power supply device according to the first embodiment operates.

FIG. 9 is a schematic configuration diagram of a power supply device according to a second embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a power supply device according to a third embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a power supply device according to a fourth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a power supply device according to a fifth embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of a control circuit of the power supply device according to the fifth embodiment.

FIG. 14 is an operation explanatory diagram of a control circuit of the power supply device according to the fifth embodiment.

FIG. 15 is an operation explanatory diagram of the control circuit of the power supply device according to the fifth embodiment.

FIG. 16 is a schematic configuration diagram of a power supply device according to a sixth embodiment of the present invention.

FIG. 17 is a schematic configuration diagram of a power supply device according to a seventh embodiment of the present invention.

FIG. 18 is a schematic configuration diagram of a power supply device according to an eighth embodiment of the present invention.

FIG. 19 is a diagram showing an application example of the power supply device according to the first embodiment to another load circuit.

FIG. 20 is a schematic configuration diagram of a power supply device according to a ninth embodiment of the present invention.

FIG. 21 is a diagram showing the characteristics of the on-duty ratio with respect to the load current and the characteristics of the on-duty ratio with respect to the switching frequency in the upper part and the lower part, respectively.

FIG. 22 is a schematic configuration diagram of a power supply device according to a tenth embodiment of the present invention.

FIG. 23 is a diagram showing the characteristics of the on-duty ratio with respect to the load current and the characteristics of the on-duty ratio with respect to the switching frequency in the upper part and the lower part, respectively.

FIG. 24 is a schematic configuration diagram of a power supply device according to an eleventh embodiment of the present invention.

FIG. 25 is a diagram showing the characteristics of the on-duty ratio with respect to the load current and the characteristics of the on-duty ratio with respect to the switching frequency in the upper part and the lower part, respectively.

FIG. 26 is a schematic configuration diagram of a power supply device according to a twelfth embodiment of the present invention.

FIG. 27 is a schematic configuration diagram of a power supply device according to a thirteenth embodiment of the present invention.

FIG. 28 is an explanatory diagram of the operation of the power supply device according to the thirteenth embodiment.

FIG. 29 is a diagram illustrating the operation of the power supply device according to the thirteenth embodiment.

FIG. 30 is an operation explanatory diagram of the power supply device according to the thirteenth embodiment.

FIG. 31 is an explanatory diagram of the operation of the power supply device according to the thirteenth embodiment.

FIG. 32 is an explanatory diagram of the operation of the power supply device according to the thirteenth embodiment.

FIG. 33 is a signal waveform diagram of each part during operation of the power supply device according to the thirteenth embodiment.

FIG. 34 is a schematic configuration diagram of a power supply device according to a fourteenth embodiment of the present invention.

FIG. 35 is a schematic configuration diagram of a power supply device according to a fifteenth embodiment of the present invention.

FIG. 36 is a schematic configuration diagram of a control circuit of a power supply device according to a sixteenth embodiment of the present invention.

FIG. 37 is an operation explanatory diagram of the control circuit shown in FIG. 36;

FIG. 38 is a schematic configuration diagram of a power supply device according to a seventeenth embodiment of the present invention.

FIG. 39 is an operation explanatory diagram of the control circuit shown in FIG. 38;

FIG. 40 is a diagram showing an application example of the power supply device according to the first embodiment to another load circuit.

FIG. 41 is an equivalent circuit diagram of FIG. 40.

FIG. 42 is a frequency characteristic diagram of the equivalent circuit shown in FIG. 40;

FIG. 43 is a schematic configuration diagram of a power supply device according to an eighteenth embodiment of the present invention.

FIG. 44 is a schematic configuration diagram of a power supply device according to a nineteenth embodiment of the present invention.

FIG. 45 is a schematic configuration diagram of a power supply device according to a twentieth embodiment of the present invention.

FIG. 46 is a schematic configuration diagram of a power supply device according to a twenty-first embodiment of the present invention.

FIG. 47 is a schematic configuration diagram of a power supply device according to a twenty-second embodiment of the present invention.

FIG. 48 is a schematic configuration diagram of a power supply device according to a twenty-third embodiment of the present invention.

FIG. 49 is a schematic configuration diagram of a power supply device according to a twenty-fourth embodiment of the present invention.

FIG. 50 is a schematic configuration diagram of a power supply device according to another embodiment of the present invention.

FIG. 51 is a signal waveform diagram of each part of the circuit shown in FIG. 50;

FIG. 52 is a schematic configuration diagram of a power supply device according to still another embodiment of the present invention.

FIG. 53 shows an alternative to a transformer (leakage transformer).
FIG. 1 is a schematic configuration diagram of a power supply device according to an embodiment of the present invention configured using two inductances.

FIG. 54 is a schematic configuration diagram of a conventional power supply device.

FIG. 55 is an operation waveform diagram over one cycle of the voltage of the AC power supply.

FIG. 56 is an explanatory diagram of a characteristic change of an input current waveform due to the capacitance of the capacitor C1.

[Explanation of symbols]

 DB rectifier D11, D12, D31, D32 Diode C10, C30 Smoothing capacitor Q1, Q2 FET T11 Transformer C11, C12, C21, C31, C32 Capacitor 10 Control circuit 11 Load circuit L1, L2 Inductance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kanda 1048, Kazuma Kadoma, Kadoma, Osaka Pref.Matsushita Electric Works, Ltd.

Claims (18)

[Claims] 1. A rectifier for rectifying AC power to DC power, a first diode having one end connected to one output terminal of the rectifier in a forward direction, and the other end of the first diode and the other of the rectifier. A smoothing capacitor connected between the output terminal, a second diode having one end connected to the other end of the first diode in the forward direction, and another end of the second diode and the other output terminal of the rectifier. A pair of switching elements connected in series, a diode connected in anti-parallel with each of the pair of switching elements, and a connection between a connection point of the pair of switching elements and one output terminal of the rectifier. A transformer having a primary winding and a secondary winding connected to a load circuit; and a first and a second core connected in parallel with the first and second diodes, respectively. Power supply and a capacitor. 2. A rectifier for rectifying AC power into DC power, a first diode having one end connected to one output terminal of the rectifier in a forward direction, and the other end of the first diode and the other of the rectifier. A smoothing capacitor connected between the output terminal, a second diode having one end connected to the other end of the first diode in the forward direction, and another end of the second diode and the other output terminal of the rectifier. A pair of switching elements connected in series, a diode connected in anti-parallel with each of the pair of switching elements, and a connection between a connection point of the pair of switching elements and one output terminal of the rectifier. A transformer having a primary winding and a secondary winding connected to a load circuit, a first capacitor connected between both output terminals of the rectifier, and a second diode. Power supply and a second capacitor which is de connected in parallel. 3. The power supply device according to claim 1, further comprising a first inductor connected in parallel with the primary winding. 4. A load circuit comprising a second inductor connected in series with the secondary winding, wherein the load circuit includes a parallel circuit of a load and a capacitor, and is provided between both ends of the secondary winding and the second inductor. The power supply device according to claim 1, wherein the power supply device is connected. 5. The power supply device according to claim 4, wherein the transformer has a leakage inductance component as the second inductor. 6. The pair of switching elements,
3. The power supply device according to claim 1, further comprising control means for performing on / off control so that at least one of a switching frequency and an on-duty ratio can be changed. 7. A control unit for changing at least one of a switching frequency and an on-duty ratio according to a voltage fluctuation of the AC power to perform on / off control on the pair of switching elements, wherein the control unit includes: 3. The control according to claim 1, wherein the on-duty ratio is mainly controlled when a rated output is supplied to the load circuit, while the switching frequency is mainly controlled when an output to the load circuit is reduced. Power supply. 8. A voltage detecting means for detecting a voltage between both ends of the smoothing capacitor, and on / off of the pair of switching elements so that at least one of a switching frequency and a duty ratio can be changed according to a detection result of the voltage detecting means. 3. The power supply device according to claim 1, further comprising control means for performing control. 9. The power supply device according to claim 1, further comprising a clamp circuit that limits an applied voltage to a predetermined voltage. 10. The power supply device according to claim 1, further comprising a capacitor connected in parallel with at least one of the pair of switching elements at least in high frequency. 11. A switching element connected between both output terminals of the rectifier via the primary winding when the voltage of the switching element is substantially equal to the voltage across the smoothing capacitor. The power supply device according to claim 1, further comprising control means for performing the control. 12. A voltage detecting means for detecting a voltage between both ends of a switching element connected between both output terminals of the rectifier via the primary winding, and the pair of voltage detecting means utilizing a detection result of the voltage detecting means. The power supply device according to claim 11, further comprising control means for performing on / off control of the switching element. 13. The power supply according to claim 1, wherein the load circuit has at least two resonance frequencies and at least one anti-resonance frequency. 14. The load circuit has a third capacitor connected to both ends of the secondary winding via a second inductor, and one end connected to both ends of the third capacitor via a third inductor. 14. The power supply device according to claim 13, comprising a discharge lamp having a pair of filaments, and a fourth capacitor connected between the other ends of the pair of filaments. 15. The power supply according to claim 14, wherein the transformer has a leakage inductance component as the second inductor. 16. A control circuit, wherein the load circuit includes a discharge lamp, and when the discharge lamp is dimly lit, the control circuit lowers the DC voltage of the smoothing capacitor to a value lower than the rated lighting. When controlling at least one of the switching frequency and the duty ratio of the pair of switching elements so as to preheat the filament of the discharge lamp, the DC voltage of the smoothing capacitor is set to a value higher than the rated lighting. 3. The power supply device according to claim 1, wherein at least one of a switching frequency and a duty ratio of the pair of switching elements is controlled. 17. The load circuit comprises a capacitor connected to both ends of the secondary winding, and a discharge lamp having a pair of filaments each having one end connected to both ends of the capacitor. 3. The power supply device according to claim 1, wherein a preheating resonance circuit is connected between both ends. 18. A rectifier for rectifying AC power to DC power, a first diode having one end connected to one output terminal of the rectifier in a forward direction, and the other end of the first diode and the other of the rectifier. A smoothing capacitor connected between the output terminal, a second diode having one end connected to the other end of the first diode in the forward direction, and another end of the second diode and the other output terminal of the rectifier. A pair of switching elements connected in series, a diode connected in anti-parallel to each of the pair of switching elements, and a connection between a connection point of the pair of switching elements and one output terminal of the rectifier. A first inductance, a second inductance connected in parallel with the first inductance together with a load circuit, and the first and second diodes, respectively. Power supply and a first and a second capacitor which is the column connection.