JPH1084671A - Power supply equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide power supply equipment which prevents abnormal boosting of a voltage impressed on a components, prevents thereby breakdown of the component and enhances safety. SOLUTION: An electrolytic capacitor C2 is connected between output terminals of a full-wave rectifier circuit DB with a high-speed diode D1 and a load circuit L interposed. A series circuit of a diode D2 and FET Q1 is connected to the opposite ends of the electrolytic capacitor C2 . Besides, a choke coil L2 is connected between the node of the high-speed diode D1 and the load circuit L and the node of the diode D2 and the FET Q1 . Since a booster chopper operation and a step-down chopper operation are conducted in combination only in the case when a voltage VL is equal to a difference between a voltage Vc2 and the absolute value |VIN| of a voltage VIN (VL=VC2 -|VIN|) at the time of ON/OFF of the FET Q), a period when the booster chopper operation is conducted is vanishes or becomes short in the case when the impedance of the load, circuit L is small, and thus abnormal boosting of the voltage Vc2 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

Conventionally, there is a power supply device equipped with a boost chopper circuit step-down chopper circuit, the input filter the power supply, as shown in FIG. 8, in which the AC power source Vs, an inductor L ₁ and capacitor C ₁ F and input filter F
-Wave rectifier circuit DB to which AC power supply Vs is connected via
A series circuit including an inductor L ₃ and an FET Q ₂ connected between output terminals of a full-wave rectifier circuit DB;
_2, a series circuit composed of a diode D ₄ and an electrolytic capacitor C ₄ connected between both ends of the capacitor, a series circuit composed of an FET Q ₃ and a diode D ₅ connected between both ends of the electrolytic capacitor C ₄ , and both ends of a diode D ₅ It is composed of a series circuit comprising an inductor connected L ₄ and the load circuit L between.

The operation of this power supply will be described. F
ETQ _2, Q ₃ is turned on / off at each frequency, F
When ETQ ₂ is turned on, as shown in FIG. 9 (a), (in the figure, indicated by the bold line) input filter F → the full-wave rectifying circuit DB → inductor L ₃ → FETs Q ₂ of paths from the AC power source Vs is power supply is, energy is accumulated in the inductor L _3. Then, the FETs Q ₂ is turned off, as shown in FIG. 9 (b), the energy stored in the inductor L ₃ during the ON period of the FETs Q ₂ via the diode D ₄ with the rectified voltage of the full-wave rectifying circuit DB electrolyte The capacitor C ₄ is charged, and a voltage generated by boosting the rectified voltage of the full-wave rectifier circuit DB is generated across the electrolytic capacitor C ₄ .

On the other hand, FETQ_ThreeWhen turned on, FIG. 9
As shown in FIG. _FourPower supply
And electrolytic capacitor C_FourFrom FETQ_Three→ Inductor L
_Four→ While power is supplied through the path of the load circuit L,
Nacta L_FourEnergy is stored in Next, FET
Q_ThreeIs turned off, as shown in FIG.
_ThreeInductor L during the ON period of_FourEnergy stored in
Is load circuit L, diode D _FiveReleased through the load
Power is supplied to the circuit L.

[0005] In the above-described power supply step-up chopper circuit composed of an inductor L ₃ and the FETs Q ₂ and the diode D ₄ has an input distortion improving function and boost function, the inductor L ₄
The FETs Q ₃ and the diode D becomes the step-down chopper circuit ₅ has a load current limiter function and the step-down function, the step-up chopper circuit and the step-down chopper circuit respectively switching element serving FETs Q _2, Q ₃ and the diode D _4, D Has _five .

[0006] In this FETs Q _2, Q ₃ and one switching element, also serves as a diode D _4, D ₅ at one diode, some of which aimed at cost reduction by reducing the number of components. As shown in FIG. 10, this power supply device includes an AC power supply Vs, an input filter F including an inductor L ₁ and a capacitor C _1, and an AC power supply V
s connected to a full-wave rectifier circuit DB and a full-wave rectifier circuit DB
The inductor L ₃ is connected between the output terminal and FETQ
A series circuit consisting of _4, the electrolytic capacitor C ₄ connected between both ends of the FETs Q ₄ and the inductor L ₄ and the load circuit L
A series circuit consisting of, and a electrolytic capacitor C ₄ and the inductor L ₃ and an anode connected to a connection point of the FETs Q ₄ and diode D ₆ Metropolitan with a cathode connected to a connection point of the inductor L _4.

The operation of the power supply will be described. F
When ETQ ₄ is turned on, as shown in FIG. 11 (a), power is supplied in a path of the input filter F → the full-wave rectifying circuit DB → inductor L ₃ → FETs Q ₄ from the AC power source Vs, the energy in the inductor L ₃ is Stored. Further, using the electrolytic capacitor C ₄ as a power source, power is supplied from the electrolytic capacitor C ₄ through a path from the inductor L ₄ → the load circuit L → the FET Q ₄ , and energy is accumulated in the inductor L ₄ .
On the other hand, when the FETs Q ₄ is turned off, as shown in FIG. 11 (b), with the energy stored in the inductor L ₃ during on the FETs Q _4, input filter F from the AC power source Vs
→ Full-wave rectifier circuit DB → Inductor L ₃ → Diode D ₆
→ power is supplied in the path of the electrolytic capacitor C _4, the electrolytic capacitor C ₄ is charged. The energy stored in the inductor L ₄ during on the FETs Q ₄ is released from the inductor L ₄ via the load circuit L and a diode D _6, energy is supplied to the load circuit L.

Further, as shown in FIG. 12, there is a power supply device shown in FIG. 10 in which a full bridge circuit 1 is connected instead of the load circuit L.
It is, FETs Q _11, a series circuit of the series circuit and FETs Q _13, Q ₁₄ of Q ₁₂ are connected in parallel, FETs Q _11, Q
Load circuit L is configured by connecting between the connection point and the FETs Q _13, a connection point Q _{14 12.}

The operation of this circuit is the same as the operation of the power supply device shown in FIG. 10 as shown in FIGS. 13 and 14, and a description thereof will be omitted. In the circuit of FIG.
ETQ ₁₁ and Q ₁₄ are turned on, FETs Q ₁₂ and Q ₁₃ are turned off,
In the circuit of FIG. 14, the FETs Q ₁₁ and Q ₁₄ are turned off,
By turning on Q ₁₂ and Q ₁₃ , the polarity of the current flowing through the load circuit L can be inverted.

[0010]

In [0005] the power supply device of FIG. 10 or FIG. 12 described above, for example, a constant switching frequency of FETs Q _4, by changing its duty ratio, controls the power supplied to the load circuit L doing. In this case, when the duty ratio is reduced, the input power decreases in the boost chopper circuit and the output power decreases in the step-down chopper. However, the characteristics of each circuit with respect to the duty ratio depend on the power supply voltage of the AC power supply Vs and the impedance of the load circuit L. Has changed due to fluctuations in

Therefore, when the duty ratio is controlled so that the output power becomes constant, the output power decreases when the impedance of the load circuit L decreases, so that the input power becomes too large or too small. May occur. When the input power is excessive than the output power, the excess energy is accumulated in the electrolytic capacitor C _4, the voltage across the electrolytic capacitor C ₄ is increased, the voltage applied to the component increases, constituted in some cases There is a problem that parts may be damaged.

Such a phenomenon becomes conspicuous when the impedance of the load is low and a large current needs to flow through the load, such as in the process of starting a high-pressure discharge lamp. That is, a constant duty ratio must be set in order to allow a large output current to flow, but the output power is reduced because the load impedance is low. On the other hand, since the input power has a value corresponding to the duty ratio, the input power becomes excessive with respect to the output power.

[0013] In Thus, by step-up chopper circuit and a step-down chopper circuit share the FETs Q _4, it was possible to reduce the number of components as compared to the power supply of FIG. 8, the FETs Q ₄ boost chopper since flows superposed switching current of the switching current down chopper circuit of the circuit, it is necessary to increase the current capacity of the FETs Q _4, a problem that the effect of cost reduction due to the reduced number of components is reduced there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to reduce the cost and prevent the input power from becoming excessive with respect to the output power, thereby improving the safety of the power supply. The purpose is to provide.

[0015]

According to the first aspect of the present invention, to achieve the above object, an AC power supply, a full-wave rectifier circuit to which the AC power supply is connected via an input filter, and a full-wave rectifier circuit are provided. A first capacitor connected between output terminals via a load circuit, a series circuit including a first rectifier element and a switching element connected in parallel between both ends of the first capacitor, a full-wave rectifier circuit and a load A first inductor connected between a connection point of the circuit and a connection point of the first rectifying element and the switching element, wherein the first capacitor has a first capacitor connected to the first capacitor when the switching element is off. When the load circuit has a low impedance, the voltage applied to the load circuit decreases and the period during which the first capacitor is charged is shortened. 1 The voltage across the capacitor can be prevented from being abnormally boosted. Further, the step-up chopper circuit and the step-down chopper circuit share not only the switching element but also the first inductor, so that the number of components can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the load circuit comprises an inductive load. In a third aspect of the present invention, in the second aspect of the present invention, the load circuit comprises the second inductive load. Since the power supply device is composed of a series circuit of an inductor and a discharge lamp, it can be applied to a discharge lamp lighting device. According to a fourth aspect of the present invention, in the second aspect of the present invention, since a small-capacity second capacitor connected in parallel with the load circuit is provided, a low-pass filter is formed by the inductive load and the second capacitor. be able to.

According to a fifth aspect of the present invention, in the second aspect of the present invention, since the second rectifying element connected in parallel with the load circuit is provided, the voltage between both ends of the load circuit is prevented from becoming negative. it can. In the invention according to claim 6, an AC power supply, a full-wave rectifier circuit to which the AC power supply is connected via an input filter,
A first capacitor connected between output terminals of a full-wave rectifier circuit via a full-bridge circuit, and a first rectifier element and a first switching element connected in parallel between both ends of the first capacitor; Circuit, and a first inductor connected between a connection point of the full-wave rectifier circuit and the full bridge circuit and a connection point of the first rectifier element and the first switching element. The series circuit of the second and third switching elements and the series circuit of the fourth and fifth switching elements are connected in parallel, and the connection point between the second and third switching elements and the fourth and fifth switching elements are connected. It is configured by connecting a load circuit between the
The first rectifying element is connected in a direction in which the first capacitor is charged via the first rectifying element when the first switching element is turned off. Is low, the voltage applied to the load circuit decreases, and the period during which the first capacitor is charged is shortened, so that the voltage across the capacitor can be prevented from abnormally increasing. Further, the step-up chopper circuit and the step-down chopper circuit share not only the first switching element but also the first inductor, so that the number of components can be reduced.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, since the load circuit comprises an inductive load,
In the invention of claim 8, in the invention of claim 7, since the inductive load is constituted by a series circuit of the second inductor and the discharge lamp, this power supply device can be applied to a discharge lamp lighting device. According to a ninth aspect of the present invention, in the seventh aspect of the present invention, a small-capacity second capacitor connected in parallel with the full bridge circuit is provided. A low-pass filter can be configured with the two capacitors.

According to a tenth aspect of the present invention, in the seventh aspect of the invention, a second rectifying element connected in parallel with the full bridge circuit is provided. It is possible to prevent the voltage between both ends from becoming negative. According to the twelfth aspect of the present invention, an AC power supply, a full-wave rectifier circuit to which the AC power supply is connected via an input filter, and a first capacitor connected via a full bridge circuit between output terminals of the full-wave rectifier circuit A series circuit including a first rectifying element and a first switching element connected in parallel between both ends of a first capacitor; a connection point between a full-wave rectifier circuit and a full-bridge circuit; A first inductor connected between the first switching element and a connection point of the first switching element, wherein the full bridge circuit includes a series circuit of the second and third switching elements and a series circuit of the fourth and fifth switching elements. And a load circuit connected between the connection point of the second and third switching elements and the connection point of the fourth and fifth switching elements, wherein the load circuit is connected to the second inductor. as well as A series circuit of lamps,
A second rectifying element and a small-capacity second capacitor are connected in parallel with the full bridge circuit, respectively, and the first rectifying element is connected via the first rectifying element when the first switching element is turned off. When the impedance of the load circuit is low, the voltage applied to the load circuit decreases, and the first capacitor is charged, as in the first or sixth aspect of the present invention. Since the period is shortened, it is possible to prevent the voltage across the first capacitor from being abnormally boosted. In addition, since the step-up chopper circuit and the step-down chopper circuit share not only the first switching element but also the first inductor, the number of components can be reduced.

[0020]

Embodiments of the present invention will be described with reference to the drawings.
I will explain. (Embodiment 1) The power supply of this embodiment is shown in FIG.
Thus, the AC power supply Vs and the inductor L ₁And capacitors
C₁Input filter F and low-speed diode
Through the input filter F
And a full-wave rectifier circuit DB to which an AC power supply Vs is connected.
High-speed diode D between output terminals of rectifier circuit DB₁And invitation
A first circuit connected via a load circuit L composed of a conductive load
Capacitor electrolytic capacitor C_TwoAnd electrolytic capacitors
C_TwoOf the first rectifier connected between both ends of the
Do D_TwoAnd switching element FET Q₁And fast
Iod D₁And the connection point of the load circuit L and the diode D_Two
And FETQ₁Of the first input connected to the connection point of
Choke coil L_TwoIt is composed of
Here, the FET Q₁And cho
Cucoil L_TwoAnd diode D_TwoFrom the boost chopper
And electrolytic capacitor C_TwoFETQ₁When
Choke coil L_TwoAnd diode D_TwoBuck chop from
Is configured.

The operation of this power supply device is shown in FIGS.
This will be described with reference to FIG. Now, the power supply voltage of the AC power supply Vs is set to V
_IN, The output voltage of the full-wave rectifier circuit DB is | V_IN| And load
The voltage V is applied to the circuit L_LIs applied to the electrolytic capacitor C_Twoof
Voltage V between both terminals_C2Is occurring. First, FIG.
As shown in FIG.₁Turns on and the voltage
V_LIs the voltage V_C2And input voltage V_INAbsolute value of | V_IN|
Position difference (V_C2− | V_IN|) (V_L<V_C2
− | V_IN|), Electrolytic capacitor C_TwoIs the load circuit L → cho
Arc coil L_Two→ FETQ₁Discharge in the path of
Cucoil L_TwoEnergy is stored in
Power is supplied to the circuit L. During this period, the voltage V_LBut
Potential difference (V_C2− | V_IN|), The diode D₁
Has V_D1(= V_C2-V _L− | V_IN|) Potential difference occurs
Energy from the AC power supply Vs to the load circuit L
Is not supplied (mode A₁).

When the FET Q ₁ is turned on and the voltage V
_{When L} rises and becomes equal to the potential difference (V _C2 − | V _IN |) (V _L = V _C2 − | V _IN |), as shown in FIG. → Full-wave rectifier circuit D
B → High speed diode D ₁ → Choke coil L ₂ → FET
Power is supplied in a path of Q _1, and energy is accumulated in the choke coil L _2, performs the step-up chopper operation. Further, the electrolytic capacitor C ₂ discharges in the path of the load circuit L → the choke coil L ₂ → the FET Q ₁ , and the choke coil L
Energy is stored in ₂ and power is supplied to the load circuit L to perform a step-down chopper operation (mode A ₂ ). Thus, in the mode A _2, step-up chopper operation and the step-down chopper operation is performed also serves.

[0023] Next, FETQ ₁ is turned off, and, voltage V _L
Is equal to the potential difference (V _C2 − | V _IN |) (V _L = V _C2
- | V _IN |), as shown in FIG. 2 (c), with the energy accumulated in the choke coil L ₂ in another mode, the input filter F → the full-wave rectifier circuit from an AC power source Vs DB → fast diodes D ₁ → Choke coil L ₂ → Diode D
₂ → power is supplied in the path of the electrolytic capacitor C _2, the electrolytic capacitor C ₂ is charged, it operates the step-up chopper.
Further, the choke coil L ₂ to accumulated energy diode D _2, released in a path of the load circuit L, power is supplied to the load circuit L, performs the step-down chopper operation (Mode A _3). Thus, modes in the mode A ₃ A ₂
Similarly, the step-up chopper operation and the step-down chopper operation are also performed.

Further, when the FET Q ₁ is off and the voltage V
_{When L} decreases and is smaller than the potential difference (V _C2 − | V _IN |) (V _L <V _C2 − | V _IN |), the energy stored in the choke coil L ₂ is reduced by the diode D ₂ and the load circuit L The electric power is discharged through the path and power is supplied to the load circuit L (mode A ₄ ). Here, only the mode A ₄ step-down chopper operation is performed.

As described above, ON / OFF of the FET Q ₁ ,
Further, the voltage V _L applied to the load circuit L changes, and the voltage V _C2 between both terminals of the electrolytic capacitor C ₂ and the AC power supply Vs
Absolute value of the input voltage V _IN of | V _IN | potential difference between (V _C2 - |
V _IN |) is equal to or less than
Mode A ₁ ~A ₄ is switched. Meanwhile, low impedance of the load circuit L, and, if it is necessary to flow a large current, for the impedance of the load circuit L is low, the voltage V _L applied to the load circuit L is not increased, the voltage V _L the potential difference _{(V C2 - | V iN |} ) to equal that there are no, or the voltage V _L potential difference (V _C2 - | V
_The period equal to _IN |) becomes shorter. As a result, one period of the mode A _2, A ₃ described above is eliminated, or, the period is shortened.

[0026] Among the above modes, periods of mode A ₂ is an AC power source Vs through a period during which energy is accumulated in the choke coil L _2, the period of the mode A ₃ is a choke coil L ₂ with an AC power source Vs it is a period in which the electrolytic capacitor C ₂ is charged by the energy stored in the. Accordingly, the mode A _2, the period of A ₃ is not generated, or that becomes shorter, the electrolytic capacitor C ₂ is not charged, or it indicates that the amount of charge is reduced, the electrolytic capacitor C ₂ It is possible to prevent the voltage V _C2 between both ends from being abnormally increased, and reduce the voltage applied to each component.

In this embodiment, the FET is used as the switching element. However, the present invention is not limited to the FET, and a switching element such as a transistor other than the FET may be used. Further, although a diode is used as the first rectifying element, a rectifying element other than the diode may be used. (Embodiment 2) In this embodiment, as shown in FIG. 3, a choke coil L as a second inductor is used as the load circuit L composed of an inductive load in the power supply device of Embodiment 1.
A series circuit of ₀ and a load resistor R is used, and a diode D _{3 as a} second rectifier and a capacitor C ₃ as a second capacitor are connected in parallel with the load circuit L, respectively.

[0028] The operation of the power supply apparatus is similar to the operation of the power supply device of Embodiment 1, the choke coil L ₀ and capacitor C ₃ is, to a low-pass filter to an actual load load resistance R Is different. That is, the change of the voltage across V _C3 of the capacitor C ₃ has to correspond to the change of the voltage V _L of the load circuit L in the first embodiment.

[0029] In addition, at the time of off FETQ _1, load circuit L
When the applied voltage V _L becomes negative, the capacitor C ₃ is discharged in a path of the choke coil L ₂ → diode D _2,
When the FETs Q ₁ is turned on, usually switching current increases from zero, it will be increased from the current FETs Q ₁ was flowing to the diode D ₂ just prior to the on loss of the switching is increased. Therefore, the power supply device of this embodiment, the load connected to the circuit L and antiparallel to the diode D _3, the load circuit voltage V _L applied to L is prevented from going negative, to reduce the loss of the switching ing.

The circuit configuration other than the load circuit L, the diode D ₃ and the capacitor C ₃ is the same as that of the first embodiment, and a description thereof will be omitted. It goes without saying that a discharge lamp may be used as the load resistor R, and a rectifier other than a diode may be used as the second rectifier. Embodiment 3 In this embodiment, as shown in FIG. 4, a full bridge circuit 1 is inserted in place of the load circuit L in the power supply device of Embodiment 1. Full bridge circuit 1
Are FETs Q _{11 as} first and second switching elements _.
A series circuit of Q _12, a series circuit of third and fourth switching elements serving FETs Q _13, Q ₁₄ are connected in parallel, F
Load circuit L between the connection point of ETQ _11, the connection point of Q ₁₂ and FETs Q _13, Q ₁₄ is connected and configured. The operation of the power supply device will be described with reference to FIGS. Now, FETQ _11, Q ₁₄ is in the ON state, F
ETQ _12, Q ₁₃ is referred to as being in the OFF state.

First, as shown in FIG.
₁Is on and the voltage V applied to the load circuit L_LExcellence
V |_L| Is the electrolytic capacitor C_TwoVoltage between both terminals of
V_C2And the voltage V of the AC power supply Vs_INAbsolute value of | V_IN|
Smaller than the potential difference (| V _L| <V_C2− | V_IN|),
Electrolytic capacitor C_TwoIs FETQ₁₁→ Load circuit L → FET
Q₁₄→ Choke coil L_Two→ FETQ₁Discharge in the path of
And choke coil L _TwoWhen energy is stored in
First, power is supplied to the load circuit L (mode B₁).

When the FET Q ₁ is turned on and the voltage V _L
Is equal to the potential difference (V _C2 − | V _IN |) (|
V _L | = V _C2 − | V _IN |), as shown in FIG.
Mode B ₁ in the same manner as in the electrolytic capacitor C ₂ is FETs Q ₁₁ →
Load circuit L → FETQ ₁₄ → Choke coil L ₂ → FET
And discharge path of Q _1, together with the energy is accumulated in the choke coil L _2, power is supplied to the load circuit L. Further, from the AC power supply Vs, the input filter F → the full-wave rectifier circuit DB → the high-speed diode D ₁ → the choke coil L ₂ →
Power is supplied by the path of the FETs Q _1, the choke coil L
Energy is stored in the ₂ (mode B _2).

Next, the FET Q ₁ is turned off and the voltage V _L
Is equal to the potential difference (V _C2 − | V _IN |) (|
V _L | = V _C2 − | V _IN |), as shown in FIG.
FETQ the energy stored in the choke coil L ₂ when _1-one, the choke coil L ₂ → diode D ₂ →
Power is supplied to the load circuit L from the FET Q ₁₁ → the load circuit L → the FET Q ₁₄ . Further, the energy stored in the choke coil L _2, the AC power source Vs
From the input filter F → the full-wave rectifier circuit DB → the high-speed diode D ₁ → the choke coil L ₂ → the diode D ₂ → the electrolytic capacitor C ₂ , and the electrolytic capacitor C ₂ is charged (mode B _3). ).

Further, when the FET Q ₁ is off and the voltage V
_When the absolute value of _L is smaller than the potential difference (V _C2 − | V _IN |) (| V _L | <V _C2 − | V _IN |), the voltage is accumulated in the choke coil L ₂ as shown in FIG. Energy is
From the choke coil L ₂ to the diode D ₂ → FET Q ₁₁ →
Released in the path of the load circuit L → FETs Q _14, the load circuit L
Is supplied with power.

Here, the polarity of the current flowing through the load circuit L is
In order to invert, as shown in FIGS.
And FETQ_11,Q₁₄Off and FET
Q₁₂, Q ₁₃You only need to turn on. FETQ₁₁~ Q₁₄On
5 / (d) except for the / off state.
The description is omitted because it is the same as the work. In addition,
The circuit configuration other than the ridge circuit 1 is the same as that of the first embodiment.
Therefore, the description is omitted. (Embodiment 4) In this embodiment, the power supply device of Embodiment 3
In FIG. 7, as shown in FIG.
Choke coil L as an inductor₀And from the discharge lamp DL
And a second circuit in parallel with the full bridge circuit 1.
Capacitor C _ThreeAre connected,
Yoke coil L₀And capacitor C_ThreeAnd low passfi
Ruta is configured.

The FE constituting the full bridge circuit 1
The parasitic diode of the TQ ₁₁ to Q _14, similarly to the diode D ₃ of the second embodiment, since never voltage across the full-bridge circuit 1 becomes negative, when the ON FETs Q _1,
The switching current rises from zero, and switching loss can be reduced. The circuit configuration other than the capacitor C ₃ and the choke coil L ₀ and the discharge lamp DL is similar to the power supply device of Embodiment 3, a description thereof will be omitted.

[0037]

As described above, according to the first aspect of the present invention, a load circuit is provided between an AC power supply, a full-wave rectifier circuit to which the AC power supply is connected via an input filter, and an output terminal of the full-wave rectifier circuit. A first capacitor connected through the first capacitor, a series circuit including a first rectifier element and a switching element connected in parallel between both ends of the first capacitor, a connection point of a full-wave rectifier circuit and a load circuit, and a first capacitor. A first inductor connected between the rectifying element and the connection point of the switching element,
The first rectifying element is connected in a direction in which the first capacitor is charged via the first rectifying element when the switching element is off, and when the impedance of the load circuit is low,
Since the voltage applied to the load circuit decreases and the period during which the first capacitor is charged is shortened, it is possible to prevent the voltage across the first capacitor from being abnormally boosted, and to prevent damage to components. This has the effect. In addition, the step-up chopper circuit and the step-down chopper circuit share not only the switching element but also the first inductor, so that the number of components can be reduced and the cost can be reduced. .

According to a second aspect of the present invention, the load circuit is constituted by an inductive load, and the third aspect of the present invention is arranged such that the inductive load is constituted by a series circuit of the second inductor and the discharge lamp. There is an effect that this power supply device can be applied to a discharge lamp lighting device. Since the invention of claim 4 includes the second capacitor having a small capacitance connected in parallel with the load circuit, there is an effect that a low-pass filter can be formed by the inductive load and the second capacitor. .

The fifth aspect of the present invention includes a second rectifying element connected in parallel with the load circuit, and can prevent the voltage between both ends of the load circuit from becoming negative, thereby reducing switching loss. There is an effect that can be. According to a sixth aspect of the present invention, there is provided a full-wave rectifier circuit to which an AC power source is connected via an input filter, and a first capacitor connected via a full-bridge circuit between output terminals of the full-wave rectifier circuit. A series circuit including a first rectifying element and a first switching element connected in parallel between both ends of a first capacitor; a connection point of a full-wave rectifying circuit and a full bridge circuit;
And a first inductor connected between the rectifier element and the connection point of the first switching element, wherein the full bridge circuit includes a series circuit of the second and third switching elements, and a fourth and fifth series circuit. And a series circuit of the switching elements is connected in parallel, and a load circuit is connected between the connection point of the second and third switching elements and the connection point of the fourth and fifth switching elements. Is connected in the direction in which the first capacitor is charged via the first rectifying element when the first switching element is turned off, and the impedance of the load circuit is low as in the first aspect of the present invention. In this case, the voltage applied to the load circuit decreases, and the period during which the first capacitor is charged is shortened. Therefore, it is possible to prevent the voltage across the capacitor from abnormally increasing.
There is an effect that damage to the components can be prevented. Also,
The step-up chopper circuit and the step-down chopper circuit share not only the first switching element but also the first inductor, so that the number of components can be reduced and the cost can be reduced. is there.

According to a seventh aspect of the present invention, since the load circuit comprises an inductive load, the eighth aspect of the present invention provides the following because the inductive load is a series circuit of the second inductor and the discharge lamp.
There is an effect that this power supply device can be applied to a discharge lamp lighting device. According to the ninth aspect of the present invention, since a small-capacity second capacitor is connected in parallel with the full-bridge circuit, a low-pass filter is formed by the inductive load and the second capacitor as in the third aspect of the invention. Has the effect of being able to configure.

According to the tenth aspect of the present invention, since the second rectifier connected in parallel with the full bridge circuit is provided, the voltage between both ends of the full bridge circuit becomes negative similarly to the fourth aspect of the present invention. And the switching loss can be reduced. According to a twelfth aspect of the present invention, there is provided a full-wave rectifier circuit to which an AC power source is connected via an input filter, and a first capacitor connected via a full-bridge circuit between output terminals of the full-wave rectifier circuit. A series circuit including a first rectifying element and a first switching element connected in parallel between both ends of a first capacitor; a connection point between a full-wave rectifier circuit and a full-bridge circuit; A first switching element connected between the first switching element and a connection point of the first switching element;
And a full bridge circuit is configured such that a series circuit of the second and third switching elements and a series circuit of the fourth and fifth switching elements are connected in parallel, and the second and third switching elements are connected in parallel. A load circuit is connected between the connection point and the connection point of the fourth and fifth switching elements, and the load circuit is formed of a series circuit of the second inductor and the discharge lamp, and is respectively parallel to the full bridge circuit. Connected to the second rectifier and a small-capacity second capacitor,
The first rectifying element is connected in a direction in which the first capacitor is charged via the first rectifying element when the first switching element is turned off.
When the impedance of the load circuit is low, the voltage applied to the load circuit decreases, and the period during which the first capacitor is charged is shortened, so that the voltage across the first capacitor is prevented from being abnormally boosted. Therefore, there is an effect that damage to the component can be prevented. Further, since the step-up chopper circuit and the step-down chopper circuit share not only the first switching element but also the first inductor, the number of components can be reduced, and the cost can be reduced. There is.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a power supply device according to a first embodiment.

FIGS. 2A to 2D are circuit diagrams showing the operation states of the above.

FIG. 3 is a circuit diagram illustrating a power supply device according to a second embodiment.

FIG. 4 is a circuit diagram illustrating a power supply device according to a third embodiment.

FIGS. 5A to 5D are circuit diagrams showing the operation states of the above.

6 (a) to 6 (d) are circuit diagrams showing different operation states of the above.

FIG. 7 is a circuit diagram illustrating a power supply device according to a fourth embodiment.

FIG. 8 is a circuit diagram showing a conventional power supply device.

FIGS. 9A and 9B are circuit diagrams showing the operation states of the above.

FIG. 10 is a circuit diagram showing another conventional power supply device.

FIGS. 11A and 11B are circuit diagrams showing the operation states of the above.

FIG. 12 is a circuit diagram showing another conventional power supply device.

FIGS. 13A and 13B are circuit diagrams showing the operation states of the above.

FIGS. 14A and 14B are circuit diagrams showing different operation states of the above.

[Explanation of symbols]

C ₂ electrolytic capacitor D ₁ high-speed diode D ₂ diode DB full-wave rectifier circuit L load circuit L ₂ choke coil Q ₁ FET _VL, V _C2, V _IN voltage

Claims (12)

[Claims] An AC power supply, a full-wave rectifier circuit to which the AC power supply is connected via an input filter, and a first capacitor connected via a load circuit between output terminals of the full-wave rectification circuit. A series circuit including a first rectifier element and a switching element connected in parallel between both ends of the first capacitor, a connection point between the full-wave rectifier circuit and the load circuit, the first rectifier element, and the switching. A first inductor connected between the switching element and a connection point of the element, wherein the first capacitor is charged via the first rectifying element when the switching element is turned off. A power supply device characterized by being connected in directions. 2. The power supply device according to claim 1, wherein said load circuit comprises an inductive load. 3. The power supply device according to claim 2, wherein said inductive load comprises a series circuit of a second inductor and a discharge lamp. 4. The power supply device according to claim 2, further comprising a small-capacity second capacitor connected in parallel with said load circuit. 5. The power supply device according to claim 2, further comprising a second rectifier connected in parallel with said load circuit. 6. A full-wave rectifier circuit to which the AC power source is connected via an input filter, an AC power source, and a first capacitor connected via a full-bridge circuit between output terminals of the full-wave rectifier circuit. A series circuit including a first rectifier element and a first switching element connected in parallel between both ends of the first capacitor; a connection point of the full-wave rectifier circuit and the full bridge circuit; A first switching element connected between a rectifying element and a connection point of the first switching element;
And the full bridge circuit is a second inductor.
And a series circuit of the third and third switching elements and a series circuit of the fourth and fifth switching elements are connected in parallel, and the connection point of the second and third switching elements is connected to the fourth and fifth switching elements.
The first rectifying element is configured such that the first capacitor is connected via the first rectifying element when the first switching element is turned off. A power supply device connected in a charging direction. 7. The power supply device according to claim 6, wherein said load circuit comprises an inductive load. 8. The power supply device according to claim 7, wherein said inductive load comprises a series circuit of a second inductor and a discharge lamp. 9. The power supply device according to claim 7, further comprising a small-capacity second capacitor connected in parallel with said full bridge circuit. 10. The power supply device according to claim 7, further comprising a second rectifier connected in parallel with said full bridge circuit. 11. The full-wave rectifier circuit comprises a low-speed diode bridge circuit, and the bridge circuit and the first
7. The power supply device according to claim 1, wherein a high-speed diode is inserted between the power supply device and the inductor. 12. A full-wave rectifier circuit connected to an AC power supply, the AC power supply via an input filter, and a first capacitor connected via a full bridge circuit between output terminals of the full-wave rectifier circuit. A series circuit including a first rectifying element and a first switching element connected in parallel between both ends of the first capacitor; a connection point between the full-wave rectifier circuit and the full bridge circuit; Rectifier and the first
A first inductor connected between the connection point of the switching element and the full bridge circuit, wherein the full bridge circuit includes a series circuit of the second and third switching elements;
Is connected in parallel with a series circuit of
A load circuit is connected between a connection point of the third switching element and a connection point of the fourth and fifth switching elements, and the load circuit is configured by a series circuit of a second inductor and a discharge lamp. A second rectifying element and a small-capacity second capacitor are connected in parallel with the full bridge circuit, respectively, and the first rectifying element is connected to the first capacitor when the first switching element is turned off. A power supply device connected in a charging direction via a first rectifying element.