JPH104688A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit which can minimize input current strain and fluctuation in current supplied to a load. SOLUTION: An AC power source AC is full-wave-rectified by a rectifying circuit RE, and the output of the rectifying circuit RE is converted into high-frequency output by an inverter circuit IVN and supplied to a load L. The inverter circuit INV is provided with a pair of switching elements Q1 , Q2 alternately turned on and off, an impedance circuit Z between the rectifying circuit RE and the switching elements Q1 , Q2 , a resonance circuit A where a serial circuit to the impedance circuit Z is connected between both ends of the switching element Q1 to take out the output to the load L, and a smoothing capacitor C0 . In the inverter circuit INV, a circuit constant is set, so that the effective value IA of current running through the resonance circuit A may be at least twice as much as the peak value of input current to the rectifying circuit RE from the AC power source AC.

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 having an AC input-AC output and a small input current distortion.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 12, an AC power supply AC is full-wave rectified by a rectifier circuit RE, and then converted into an AC output by an inverter circuit INV, so that AC input-AC output power conversion is performed. There is provided a power supply device which performs the operation (see JP-A-5-38161, JP-A-7-73988, etc.). In this type of power supply, it is required to increase the input power factor and reduce the input current distortion.

[0003] In the power supply device shown in FIG.
Inverter circuit INV using a diode bridge for E
Is a pair of switching elements consisting of MOSFETs
Q₁, Q _TwoWith both switching elements
Q₁, Q_TwoSeries circuit is diode D ₀Commutation times through
It is connected between the DC output terminals of the path RE. In addition, both sui
Switching element Q₁, Q_TwoSmoothing capacitor in series circuit
C₀Are connected in parallel. Diode D₀Is relatively small
Amount of capacitor C₁Are connected in parallel, and the rectifier circuit RE
Pole output terminal and both switching elements Q₁, Q_TwoConnection points and
In between, capacitors for coupling (for DC cut)
C_Three, Load L, and resonance inductor L₁Series circuit with
Connected. Further, the load L has a capacitor C for resonance.
_TwoAre connected in parallel.

[0004] Both switching elements Q₁, Q_TwoShows
Not turned on and off alternately at high frequency by a control circuit
You. The operation of the inverter circuit INV will be briefly described.
Switching element Q_TwoWhen the rectifier circuit RE
Capacitor C_Three-Load L (capacitor C_Two) -Inductor
L₁-Switching element Q_TwoCurrent flows through the
Switching element Q_TwoWhen the inductor is off, the inductor L₁Accumulation of
The regenerative current generated by the energy is the switching element Q₁of
Parasitic diode-smoothing capacitor C₀-Rectifier circuit RE-
Capacitor C_Three-Load L (capacitor C_TwoFlow)
It is. Also, the switching element Q₁Is turned on,
Capacitor C_ThreeFrom capacitor C₁(Diode D₀)-
Switching element Q₁-Inductor L₁-Load L (con
Densa C _Two), Current flows through the switching element Q
₁Turns off, the inductor L ₁Regenerative current is load L
(Capacitor C_Two) -Capacitor C_Three-Capacitor C₁
(Diode D₁) -Smoothing capacitor C₀-Switchon
Element Q_TwoFlows through the path of the parasitic diode.

As is apparent from the above operation, FIG.
In the circuit shown in FIG. 2, since the current flows from the rectifier circuit RE to the inverter INV at a time interval sufficiently shorter than one cycle of the voltage waveform of the AC power supply AC, the input current flows in the rectifier circuit RE at a high frequency. Become. Therefore, the filter circuit FL for blocking high frequency is connected to the AC power supply AC and the rectifier circuit R.
By providing the voltage between E and E, the input current from the AC power supply AC has a substantially continuous waveform, and input current distortion can be reduced.

Incidentally, the output voltage V of the rectifier circuit RE is
_ACAnd the smoothing capacitor C₀Voltage V _C0And conden
Sa C₁Voltage V_C1Is as shown in FIG.
Output voltage V of rectifier circuit RE_ACIs a pulsating voltage waveform,
Smoothing capacitor C₀Is V _C0Becomes almost constant.
The capacitor C₁Is the switching element Q₁, Q_Twoof
Since charge / discharge is repeated by ON / OFF,
Sensor C₁Voltage V_C1Has a high-frequency vibration waveform.
Is the smoothing capacitor C₀Voltage V_C0And rectifier circuit
RE output voltage V_ACAnd the difference. Here, the rectifier circuit R
Output voltage V of E_ACThan smoothing capacitor C₀Voltage across
Is high because the inductor L₁And switching element Q_TwoWhen
Switching element Q₁Parasitic diode and smoothing capacitor
Sa C₀Function as a boost chopper circuit,
L₁Capacitor C using the stored energy of₀Both
Because the terminal voltage is increased more than the output voltage of the rectifier circuit RE.
is there. Thus, the smoothing capacitor C₀Voltage V_C0
Always the output voltage V of the rectifier circuit RE_ACAs above
In the following, smoothing is called perfect smoothing, and smoothing
Capacitor C₀Voltage V_C0Is the output voltage of the rectifier circuit RE
The case where a lower period occurs is called partial smoothing. However
And the capacitor C₁Voltage V_C1The amplitude of the rectifier circuit
RE output voltage V_ACLarge at the valley (around 0V)
(Around the peak value). In the following, FIG.
The operation of the power supply device that has been_ACof
It will be discussed in more detail by dividing into mountains and valleys.

First, in the valley, the capacitor C₁Both
Terminal voltage V_C1Is large and the capacitor C ₁Works effectively
Therefore, a resonance circuit system as shown in FIG.
Is done. Here, the capacitor C_ThreeIs for coupling
The switching element Q₁, Q_Two
Ignore the switching frequency that turns on and off
Can be The resonance frequency fd of this resonance circuit system is a number
It is expressed by Equation (1).

Further, since the ridge portions can be ignored almost voltage across the capacitor C _1, the resonance circuit system becomes shaped like FIG. 14 (b), the resonance frequency fc is the number 1 (2) It is expressed by an equation.

[0009]

(Equation 1)

Here, the power supply E ₀ shown in FIG. 14 is obtained by the voltage V _C0 across the smoothing capacitor C ₀ and the voltage across the capacitor C ₃ . As evidenced by the above discussion, the resonant frequency changes between fd and fc in accordance with the output voltage V _AC of the variation of the rectifier circuit RE. In the valley, the series circuit of the capacitors C ₁ and C ₂ constitutes a part of the series resonance circuit. Therefore, the resonance circuit system shown in FIG. 14A is larger than the resonance circuit system shown in FIG. The resonance frequency will be high. That is, fd> fc. The switching frequency at which the switching elements Q ₁ and Q ₂ are turned on and off is set to a value higher than the resonance frequency of the resonance circuit system, so that the resonance frequency approaches the switching frequency in the valleys rather than the peaks. That is, the supply current I _L to the load _L
As shown in FIG. 15, (shown in relation to the supply current I _L AC power supply AC voltage V _in to FIG. 15, the load L) towards the valley is larger than the crest portion.

As is apparent from the above description, in the circuit configuration of FIG. 12, although the input current distortion is improved, the load L
There is a variation in the supply current I _L to, for example, if those using discharge lamp as the load L, since the fluctuation period of the supply current I _L is about one-half of the voltage cycle of the AC power source AC,
The light output fluctuates, causing flicker. Therefore, the supply current I _L to the load L by varying the switching frequency of turning on and off the switching elements Q _1, Q ₂ in accordance with a variation in the output voltage V _AC rectifier circuit RE
Is considered to be controlled to be substantially constant.

By the way, in one cycle of the AC power source AC, and supply current to the load L, the effective value of the current flowing in the capacitor C _2, and the current flowing through the inductor L _1, a current flowing from the AC power source AC to the power supply _Are represented by I _L , I _C2 , I _L1 , and I _in , respectively, and the current supplied to the load L and the current flowing to the capacitor C ₂ have a phase of 9
Since they differ by 0 degrees, the relationship of Equation 2 is established.

[0013]

(Equation 2)

The output current I ₁ of the rectifier circuit RE flows only when the switching element Q ₂ is on as described above,
Since the ON / OFF cycle T of the switching elements Q ₁ and Q ₂ is sufficiently shorter than the voltage cycle of the AC power supply AC, the current I ₁ during the ON period of the switching element Q ₂ can be considered to be substantially constant. Now, the peak value of the input current from the AC power supply AC to the power supply device is defined as _{Iin (peak),} and the output current of the rectifier circuit RE when the peak value _{Iin (peak)} is obtained is defined as I1 _(peak) . . Since the current value of the input current from the AC power supply AC can be considered as an average value of the output current of the rectifier circuit RE in the cycle T, the relationship of Expression 3 can be obtained.

[0015]

(Equation 3)

Equation 3 assumes that the input current from the AC power supply AC to the power supply is sinusoidal. Meanwhile, as shown in FIG. 17 is a substantially the same structure as those described in Japanese Patent Application No. Hei 6-291751, the circuit configuration shown in FIG. 12, the rectifier circuit RE and the diode D ₀
Insert the diode D ₁ between the smoothing capacitor C ₀
Place of the valley filled circuit provided, in which were further connected a relatively small capacity capacitor C ₄ between the output ends of the rectifier circuit RE. The load L uses a secondary winding of the transformer T ₁ connected to the discharge lamp DL, and the capacitor C ₂ uses the discharge lamp D
It is connected to the non-power supply side of the L filament. FIG. 17 shows a control circuit CN for controlling the switching elements Q ₁ and Q ₂ .

The valley circuit is a diode D_TwoAnd inductor
L_TwoAnd smoothing capacitor C₀Switching series circuit with
Element Q_TwoAnd a smoothing capacitor C₀And Daio
Do D _ThreeAnd the switching circuit Q₁, Q_Twoof
A diode connected in parallel with a series circuit_Two
And smoothing capacitor C₀And the capacitor C _Five
Are also connected in parallel. Diode D_TwoIs a smoothing capacitor
C₀Is connected to a polarity that allows a charging current to flow through the diode D._Three
Is the smoothing capacitor C₀Is connected to the polarity that allows the discharge current to flow
ing. In this valley circuit, the output voltage of the rectifier circuit RE is flat.
Smoothing capacitor C ₀During periods higher than the terminal voltage of
Switching element Q₁When the diode D is on_TwoAnd Inn
Dacta L_TwoThrough the smoothing capacitor C₀Charge and also
The output voltage of the rectifier circuit RE is a smoothing capacitor C₀Terminal power
During the period lower than the pressure, the diode D_ThreeThrough smooth
Capacitor C₀Is discharged and the smoothing capacitor C₀Is Invar
It functions as a power supply for the inverter circuit INV. Therefore, die
Aether D_TwoAnd inductor L _TwoAnd smoothing capacitor C₀And su
Switching element Q₁And switching element Q_TwoThe parasitic die
The step-down chopper circuit is constituted by the ode.

FIG. 18 shows the operation of each part of the circuit shown in FIG.
(A) is a voltage waveform of the AC power supply AC, (b)
Is the input current waveform from the AC power supply AC, and (c) is the capacitor
Sa C _Five(D) is the lamp current of the discharge lamp DL.
Show. As is clear from FIG.
The power supply voltage of NV is a period during which the output voltage of the rectifier circuit RE is high.
(Mountain) is the output voltage of the rectifier circuit RE,
During the period when the RE output voltage is low (valley), a smoothing capacitor
C₀Terminal voltage. In other words, the valley circuit is rectified
It functions to fill the valley of the output voltage of the circuit RE.

In the circuit configuration shown in FIG. 17, the supply current to the discharge lamp DL is large at the peak of the output voltage of the rectifier circuit RE, as in the case of the partial smoothing operation in the circuit configuration shown in FIG. , although to become less in the valleys, do not fall input voltage to the inverter circuit INV (terminal voltage of the capacitor C ₅₎ is so even in the valley, the supply current to the discharge lamp DL as shown in FIG. 18 (d) Is relatively small, and the crest factor (= peak value / effective value) of the current supplied to the discharge lamp DL is reduced. As a result, the discharge voltage of the output voltage of the rectifier circuit RE at the peaks and valleys is reduced. Fluctuations in the light output of the electric light DL can be reduced. In this configuration, by providing the valley filling circuit, the crest factor of the current supplied to the load L can be reduced without changing the switching frequency of the switching elements Q ₁ and Q ₂ according to the output voltage of the rectifier circuit RE. can do. Moreover,
As in the first embodiment, the input current distortion can be reduced.

Consider the circuit shown in FIG. 17 in more detail. Now, the current flowing through the discharge lamp DL and the effective value of the current flowing through the capacitor C _2, respectively I _L, and I _C2, the Makihi the primary winding and the secondary winding of the transformer T ₁ 1:
Assuming that n, the relationship between the effective value I _{T1 (1)} of the current flowing through the primary winding of the transformer T ₁ and the currents I _L and I _C2 is expressed by Equation 4. Here, the current _IL and the current _IC2 have a phase difference of 90 degrees.

[0021]

(Equation 4)

[0022]

SUMMARY OF THE INVENTION In the structure shown in FIG.
Is the inductor L₁Current I flowing through_L1Is the rectifier circuit RE
Output current I_{1 (peak)}Is equal to diode D₀To
No current flows, but the switching element Q₁, Q_TwoSui
Depending on the setting of the switching frequency and the constant of each part,
_{1 (peak)}Than the current I_L1May be smaller. Toes
And diode D₀There is a period during which current flows through
In this case, the input from AC power supply AC
Part of the input current is diode D₀Through the smoothing capacitor
C₀Will be charged directly. As shown in FIG.
U, smoothing capacitor C₀Voltage V _C0Is the rectifier circuit R
Output voltage V of E_ACPeriod that is lower than the peak value of
It is a minute smoothing operation. As a result, the load L
Supply current I_LDepends on the output voltage of the rectifier circuit RE.
Then, the supply current I to the load L_LIs reduced.
That is, if a discharge lamp is used for the load L, the light output
Will fluctuate and flicker will occur. FIG.
(B) As shown in FIG.
When the force current is near the peak value of the voltage waveform, the diode D₀of
The input current waveform is sinusoidal because it increases due to conduction.
And the problem that the input current distortion increases
You.

In the conventional configuration shown in FIG. 17, as in the circuit example shown in FIG. 12, the output of the rectifier circuit RE depends on the switching frequency at which the switching elements Q ₁ and Q ₂ are turned on and off and the setting of the constants of each part. There may be a period during which the current I _{T1 (1)} flowing through the primary winding of the transformer T ₁ is smaller than the current I ₁ . That is, a relationship such as Equation 5 may be obtained.

[0024]

(Equation 5)

[0025] When such conditions are satisfied, since only the current from the AC power source AC can not be appropriated current to the primary winding of the transformer T _1, the capacitor C ₁ the shortage from the capacitor C ₅ Will be supplied via In other words, the voltage V _C1 across the capacitor C ₁ is
(C), the made the difference between the voltage across V _C5 of the output voltage V _AC and capacitor C ₅ of the rectifier circuit RE to the high-frequency vibration waveform amplitude. Here, (a) in FIG. 19 is an AC power supply AC voltage waveform, (b) is a supply current I _L of the input current from the AC power source AC, to (d) are the discharge lamp DL.

Under the above conditions, the voltage V _C5 across the capacitor C ₅ is kept at a constant voltage that is always higher than the output voltage of the rectifier circuit RE (that is, it becomes completely smooth). As is apparent from comparison with FIG.
Since in the conditions portion smoothing is not satisfied, the supply current I _L to the discharge lamp DL valleys is smaller than the mountain portions of the output voltage of the rectifier circuit RE. That is, the optical output fluctuates and flicker occurs.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device capable of reducing input current distortion and reducing fluctuations in supply current to a load. It is in.

[0028]

According to a first aspect of the present invention, there is provided a rectifier circuit for rectifying an AC power supply, and an inverter circuit for converting an output of the rectifier circuit into a high-frequency output and supplying the output to a load,
The inverter circuit includes a pair of switching elements connected in series and alternately turned on and off, an impedance circuit interposed between a DC output terminal of the rectifier circuit and a series circuit of both switching elements, a capacitor and an inductor. A series circuit with the impedance circuit is connected between both ends of one switching element, and a resonance circuit for taking out an output to a load; and a smoothing capacitor connected in parallel to the series circuit of both switching elements. The circuit constant is set so that the effective value of the current flowing through the circuit is at least twice the peak value of the input current from the AC power supply to the rectifier circuit.

According to a second aspect of the present invention, in the first aspect, the rectifier circuit is a diode bridge, a capacitor is connected between the DC output terminals of the rectifier circuit, and the DC output terminal of the rectifier circuit is connected to the inverter circuit. And a diode is inserted in the forward direction. According to a third aspect of the present invention, in the first aspect of the present invention, the resonance circuit connects a first capacitor for DC cut-off, an inductor and a second capacitor for resonance, and a load to a secondary side. A winding has a transformer connected in series with a first capacitor and an inductor. The second capacitor is connected in parallel to a load, and an effective value of a current flowing through the resonance circuit is an effective value of an input current from the AC power supply to the rectifier circuit. The winding ratio of the transformer is set so as to be twice or more the peak value.

According to a fourth aspect of the present invention, in the first aspect, the resonance circuit includes a first capacitor for cutting DC, an inductor and a second capacitor for resonance,
A load is connected to the secondary side, and a primary winding comprises a transformer connected in series with the first capacitor and the inductor.
Is connected between both ends of the primary winding of the transformer, and the turns ratio of the transformer is set so that the effective value of the current flowing through the resonance circuit is at least twice the peak value of the input current from the AC power supply to the rectifier circuit. Is set.

According to a fifth aspect of the present invention, in the first aspect, the resonance circuit includes a transformer having a load connected to a secondary side, and at least one of a primary winding and a secondary winding of the transformer. A tap is provided on one side, and a switch element that is opened and closed according to an output to a load is provided between one end of the winding provided with the tap and the tap, and an effective value of a current flowing through the resonance circuit is changed from an AC power supply to a rectifier circuit. Characterized in that the turns ratio of the transformer and the position of the tap are set so as to be at least twice the peak value of the input current to the transformer.

According to a sixth aspect of the present invention, there is provided a rectifier circuit for rectifying an AC power supply, and an inverter circuit for converting an output of the rectifier circuit into a high-frequency output and supplying the output to a load, wherein the inverter circuits are connected in series with each other and A pair of switching elements that are turned on and off, an impedance circuit interposed between a DC output terminal of the rectifier circuit and a series circuit of both switching elements, and a series circuit of the impedance circuit including a capacitor and an inductor. And a resonance circuit connected between both ends of the switching element for taking out the output to the load, and storing a part of the output of the inverter circuit during a high period of the DC output voltage of the rectifying circuit and determining the stored energy during a low period. A valley-filling circuit for applying a voltage to both ends of a series circuit of both switching elements; Value, characterized in that the double circuit constants to be equal to or less than the peak value of the input current to the rectifier circuit from an AC power source is set.

According to a seventh aspect of the present invention, in the sixth aspect, the rectifier circuit is a diode bridge, a capacitor is connected between the DC output terminals of the rectifier circuit, and the DC output terminal of the rectifier circuit is connected to the inverter circuit. And a diode is inserted in the forward direction. According to an eighth aspect of the present invention, in the sixth aspect, the resonance circuit connects a first capacitor for DC cut-off, an inductor and a second capacitor for resonance, and a load on a secondary side, and A winding has a transformer connected in series with a first capacitor and an inductor. The second capacitor is connected in parallel to a load, and an effective value of a current flowing through the resonance circuit is an effective value of an input current from the AC power supply to the rectifier circuit. The winding ratio of the transformer is set so as to be less than twice the peak value.

According to a ninth aspect of the present invention, in the sixth aspect, the resonance circuit includes a first capacitor for cutting a direct current, an inductor and a second capacitor for resonance,
A load is connected to the secondary side, and a primary winding comprises a transformer connected in series with the first capacitor and the inductor.
Is connected between both ends of the primary winding of the transformer, and the turns ratio of the transformer is set so that the effective value of the current flowing through the resonance circuit is less than twice the peak value of the input current from the AC power supply to the rectifier circuit. Is set.

According to a tenth aspect, in the sixth aspect, the resonance circuit includes a transformer having a load connected to a secondary side, and at least one of a primary winding and a secondary winding of the transformer. A tap is provided on one side, and a switch element that is opened and closed according to an output to a load is provided between one end of the winding provided with the tap and the tap, and an effective value of a current flowing through the resonance circuit is changed from an AC power supply to a rectifier circuit. Characterized in that the turns ratio of the transformer and the position of the tap are set so as to be not more than twice the peak value of the input current to the transformer.

According to an eleventh aspect of the present invention, in the sixth aspect of the invention, the valley filling circuit includes a smoothing capacitor connected between the DC output terminals of the rectifier circuit via one switching element. It is characterized in that the smoothing capacitor is charged when turned on. According to a twelfth aspect of the present invention, in the first or sixth aspect, the load is a discharge lamp having a filament, and wherein
A transformer having a discharge lamp connected to the next winding via a DC blocking capacitor, a first resistor connected between the non-power supply terminals of the filament, a power supply side terminal of one filament, and a DC output of a rectifier circuit. The second and third resistors for voltage division inserted between the negative electrode at one end and the other of the transformer which is the power supply side of the other filament and the positive side of the DC output terminal of the rectifier circuit.
A fourth resistor inserted between one end of the next winding and a control circuit for controlling so as to keep the switching element off when no load is detected based on the potential at the connection point of the second and third resistors; It is characterized by having.

According to a thirteenth aspect of the present invention, in the first or the sixth aspect of the present invention, the load is a discharge lamp having a filament, and the resonance circuit is connected to a secondary winding via a DC blocking capacitor. A first resistor connected between a non-power supply end of the filament, and a voltage divider for voltage division inserted between a power supply end of one filament and a negative electrode of a DC output end of the rectifier circuit. A DC power supply is obtained by rectifying and smoothing the voltage between both ends of a power supply winding provided on one of the second and third resistors, the inductor and the transformer, and having one end connected to the negative electrode of the DC output terminal of the rectifier circuit. Means,
When no load is detected based on the potential of the fourth resistor inserted between the power source side of the other filament and the DC power source and the connection point of the second and third resistors, control is performed so as to keep the switching element off. And a control circuit that performs the control.

According to the first to thirteenth aspects of the present invention, in an inverter circuit including an impedance circuit between a rectifier circuit and a smoothing capacitor and including a resonance circuit including a load, the inverter circuit includes a resonance circuit including a load. The circuit constants are set so that the relationship between the peak value and the effective value of the current flowing through the resonance circuit becomes a predetermined relationship.This relationship reduces input current distortion and reduces fluctuations in the current supplied to the load. It becomes possible to make it relatively small.

According to the first to fifth aspects of the present invention, the current flowing in the resonance circuit changes in response to the pulsating waveform of the output voltage of the rectifier circuit, but the switching frequency for turning on and off the switching element is adjusted. Thus, a change in current can be easily suppressed, and as a result, a change in current supplied to the load can be suppressed. For example, if the load is a discharge lamp, fluctuations in light output can be suppressed and flicker-free illumination light can be obtained.

In the configurations of claims 6 to 11, since the crest factor of the current supplied to the load is small, the fluctuation of the current supplied to the load is small without changing the switching frequency for turning on and off the switching element. In addition, the power factor of the power supplied to the load is relatively high. Further, since the voltage applied to the valley filling circuit is relatively low, a component having a low withstand voltage can be used as a component. Furthermore, in the configuration of claim 11, since the switching element of the inverter circuit is interposed in the charging path to the smoothing capacitor, it is possible to suppress the generation of the rush current due to the charging current flowing directly from the rectifier circuit to the smoothing capacitor. .

In the structure of claim 12 and claim 13,
The load is a discharge lamp and a DC circuit is formed in the path that passes through the filament.When the discharge lamp is removed, control is performed to keep the switching element off. Generation can be prevented. Further, in the configuration of claim 12, a fourth resistor is inserted between the primary side and the secondary side of the transformer, and in the configuration of claim 13, the power supply winding provided on one of the inductor and the transformer is used. Since power is supplied to the DC circuit, a resistor is inserted or insulated between the AC power supply and the discharge lamp. Electric current does not flow and electric shock can be prevented.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) As shown in FIG.
It has the same circuit configuration as the conventional configuration shown in FIG. 2, and is characterized in that the condition of Expression 6 is defined as a design condition. That is,
The object of the present invention is to prevent an increase in input current distortion and a change in optical output by introducing a design condition which has not been recognized conventionally.

Now, in FIG. 1, the load L and the capacitor C
A circuit constituted by C ₂ and C ₃ and the inductor L ₁ is a resonance circuit A, and a capacitor C ₁ and a diode D ₀ are an impedance circuit Z. As is apparent upon consideration of the prior art, to suppress the increase of the input current distortion, to achieve the purpose of suppressing the variation of the light output, the voltage across the smoothing capacitor C ₀ is the output voltage V _AC rectifier circuit RE Is required to be always higher than the peak value of. Moreover, to keep the voltage across the smoothing capacitor C ₀ to the constant voltage is desired. Therefore, when the effective value of the input current from the AC power supply AC to the power supply device is I _in and the effective value of the input current from the rectifier circuit RE to the resonance circuit A is I _A , the relationship of Expression 6 is established. Is set to the constant value of the inverter circuit INV.

[0044]

(Equation 6)

Here, the value obtained by multiplying the effective value I _in of the input current by two times the square corresponds to the peak value of the input current from the AC power supply AC to the rectifier circuit RE.
It becomes a condition that is set to more than twice the peak value of the input current effective value of the current I _A flowing to. As explained in the number 3 of the electrically-type, the output current I ₁ of the rectification circuit RE, if the diode D ₀ is kept turned off, the flow only when the switching element Q ₂ is turned on, the switching element Q since _1, the period T of the on-off of Q ₂ is sufficiently short when compared to the voltage cycle of the AC power supply AC, it can be considered as shown in FIG. 2, the current I ₁ in the oN period of the switching element Q ₂ is substantially constant . As a result, the relational expression shown in Expression 3 is obtained.

On the other hand, assuming that the current flowing from the impedance circuit Z to the point C in FIG. 1 is I _Z , the output of the rectifier circuit RE when the switching element Q ₂ is on near the peak value I _{in (peak) of} the input current. current I ₁ and _(peak), and the current I _a flowing current I _z in the resonant circuit a, a relation of the following equation. I _{1 (peak)} + I _Z = I _A By applying the relational expression of Equation 3 to this, the relation of Equation 7 is obtained.

[0047]

(Equation 7)

Here, since the circuit constants are set so that the relationship of Expression 6 is established, a relationship of I _Z ≧ 0 is obtained as a result. That is, when the switching element Q ₂ is turned on and the current flow I _Z, the current I
_Z is considered to flow through the impedance circuit Z- resonant circuit A- path of the switching element Q ₂ from the smoothing capacitor C _0. That is, the voltage V _C0 across the smoothing capacitor C ₀ is higher than the output voltage V _AC of the rectifier circuit RE, so that V _AC <V _C0 holds. Although the above consideration is made around the peak value I _{in (peak)} of the input current, if it is established near the peak value I _{in (peak)} , it is established in other periods. voltage across the smoothing capacitor C ₀ is the condition that high is satisfied than the output voltage V _AC rectifier circuit RE for all periods of the voltage cycle.

As a result of the above-described operation, the operation is always complete.
The smoothing operation is satisfied, and the partial smoothing operation
This can prevent an increase in input current distortion. Also,
As described as the operation of the conventional example, in the completely smooth operation
The supply current to the load L is the output voltage of the rectifier circuit RE
V_ACAnd the light output periodically fluctuates,
This variation is equal to the output voltage V_ACSui according to
Switching element Q₁, Q _TwoSwitching on and off
Can be suppressed by changing the frequency
You.

In this embodiment, various modifications are possible.
Thus, the resonance circuit A includes the load L and the capacitor C and the
Can be configured by appropriately combining the conductance
You. Further, the impedance circuit Z is a suitable impedance circuit.
It is possible to configure using a source element. (Embodiment 2) As shown in FIG.
Of the rectifier circuit RE
Very small capacitor C_FourAnd rectifier
Road RE and capacitor C₁Diode D_TwoInsert
It was done. Capacitor C _FourAnd diode D_Two
Has a fast recovery function for the rectifier circuit RE.
It is provided for. That is, the capacitor C_FourAccumulated in
The charge is stored in the capacitance component inherent in the rectifier circuit RE using the charge.
Rectifier circuit RE
To reduce the time required for reverse recovery of a rotating diode
Has ability. This makes it possible for the high-frequency current to flow
It is not necessary to use an expensive high-frequency circuit for the flow circuit RE.
And can be provided relatively inexpensively. other
Is the same as in the first embodiment.

[0051] (Embodiment 3) This embodiment, as shown in FIG. 4, in which is interposed a transformer T ₁ for power supply to the load L in the circuit configuration shown in embodiment 2. That is, the primary winding of the transformer T ₁ is inserted between the capacitor C ₃ and the inductor L _1, with each other to connect the load L and the capacitor C ₂ to the secondary winding of the transformer T _1.
The turns ratio between the primary winding and the secondary winding of the transformer T ₁ is 1: n, and by setting n to a value larger than 1, it is required to apply a relatively high voltage as the load L. Can be used. For example, when a discharge lamp is used as a load, a relatively high starting voltage is required.
By setting a larger value, it is possible to cope with a case where the starting voltage is considerably higher than the voltage of the AC power supply AC. Further, there is from the power supply side load side is insulated by transformer T _1, an advantage that is not to shock, such as during replacement of the load L.

The condition setting of the circuit constants is the same as in the first embodiment, and the circuit constants are set so as to satisfy Equation 6.
At this time, since the relationship between the current of the primary side and the secondary side of the transformer T ₁ is represented by the number 4, the I _{T (1)} in Equation 4 I
_When the relationship of Equation 6 is applied instead of _A , Equation 8 is obtained.

[0053]

(Equation 8)

Here, V _L is the effective value of the voltage applied to the load L. By setting the winding ratio of the transformer T ₁ as thus becomes a condition of Equation 8 can be kept always higher than the output voltage of the rectifier circuit RE the voltage across the smoothing capacitor C _0, resulting in the input current Distortion can be reduced. The load L uses a discharge lamp and may be a single lamp. However, as shown in FIG. 5A, two discharge lamps DL may be connected in series, or as shown in FIG.
_{A configuration in} which a plurality of discharge lamps DL are connected via the _{second unit 2} may be used as the load L. Other configurations and operations are the same as those of the first embodiment.

[0055] (Embodiment 4) This embodiment, as shown in FIG. 6, the configuration of the embodiment 3 shown in FIG. 4, a capacitor C _2, instead of parallel connection of the capacitor C ₂ to the load L It has a configuration connected in parallel to the primary winding of the transformer T _1. In this configuration, by providing the capacitor C ₂ to the primary side of the transformer T _1, it becomes possible to set lower the withstand voltage of the capacitor C _2. In the case of this configuration, the relationship of Expression 9 is obtained.

[0056]

(Equation 9)

When the relationship of Expression 6 is applied to Expression 9, the relationship of Expression 10 is obtained, and the condition regarding the turns ratio of the transformer T ₁ is determined.

[0058]

(Equation 10)

Equation 10 is set so as to satisfy Equation 6.
Therefore, naturally, the smoothing capacitor C₀of
Keep the voltage between both ends higher than the output voltage of the rectifier circuit RE.
Condition. Other configurations and operations are the same as in the first embodiment.
It is. (Embodiment 5) This embodiment corresponds to Embodiment 3 shown in FIG.
In the configuration shown in FIG.₁Of 1
Provide a tap on the secondary winding and between one end of the primary winding and the tap
Switch element S₁Is inserted. Transformer T
₁Of the primary winding and the secondary winding of the switch element S₁To
Set so that the secondary side is boosted even when turned off
I have. Other configurations are the same as those of the third embodiment.
The switch element S₁Turn on the transformer
T₁Turns ratio increases and the secondary voltage rises.
Become. For example, when the load L is a discharge lamp and dimming is performed.
Has a switch element S₁Off, and switch
Switch element S₁Turn on. Thus, the load L
Switch element S according to the output of₁On and off
And can satisfy the condition of Equation 6. Output of load L
The force is, for example, the switching element Q ₁, Q_TwoOn off
Switching depending on the switching frequency
You.

In the present embodiment, when the tap and the switch element S ₁ are provided on the secondary side of the transformer T ₁ , and the output of the load L is switched even when the capacitor C ₂ is provided on the primary side, the condition of Expression 6 is satisfied. The effect of being able to satisfy can be achieved. Other configurations and operations are the same as those of the first embodiment. (Embodiment 6) As shown in FIG.
In the configuration of the second embodiment shown in FIG.
_A valley-filled circuit is provided instead of ₀ . The valley filling circuit functions in the same manner as that described in the conventional example shown in FIG. Speaking in another aspect, the present embodiment has a configuration obtained by omitting the transformer T ₁ with respect to the conventional circuit shown in FIG. 17.

As discussed in connection with the conventional configuration shown in FIG. 17, when a valley-filled circuit is involved, circuit constants must be set so that the condition of Equation 5 is not satisfied. That is, the condition setting shown in Expression 11 is required.

[0062]

[Equation 11]

Here, the square of the effective value I _in of the input current from the AC power supply AC to the rectifier circuit RE, which is 2 times the square, corresponds to the peak value of the input current. The condition is that the effective value of _A is set to twice or less the peak value of the input current. As discussed in the first embodiment, the AC power source AC and a current I _Z flowing through the resonant circuit current flowing in the A I _A and the impedance circuit Z when the switching element Q ₂ in the vicinity of the peak value of the input current is on
And the effective value I _{in of the} current flowing from the power supply to the power supply has the relationship of Expression 7, and if Expression 11 is applied to Expression 7, I _Z ≦ 0
become. In other words, the diode D ₂ from the diode D ₀ to when the switching element Q ₂ is conductive to the rectifier circuit RE
The current in the path through diode D ₀ and capacitor C ₅ will flow. Here, neglecting the forward voltage drop of the diode D _0, D _2, the voltage across the capacitor C _C5 becomes V _C5 ≒ V _AC.

That is, the voltage V _C5 across the capacitor C ₅ is as follows according to the magnitude relationship between the output voltage V _AC of the rectifier circuit RE and the voltage V _C0 across the smoothing capacitor C ₀ . When V _AC ≧ V _C0 , V _C5 ≒ V _{AC When} V _AC <V _C0 , V _C5 = V _{C0 where the} voltage V _C0 across the smoothing capacitor C ₀ is higher than the peak value of the output voltage V _AC of the rectifier circuit RE. Is also set to be low. Thus, voltage V across the capacitor C _5
C5 is lower than the peak value of the output voltage V _AC rectifier circuit RE, becomes operation portion smooth.

By satisfying the above conditions, the load L
The fluctuation of the current supplied to the load L is reduced, and no flicker occurs due to the fluctuation of the light output even when a discharge lamp is used as the load L. Further, cost reduction is a voltage applied to the capacitor C ₅ because lower than the peak value of the rectifier circuit RE can be set relatively low withstand voltage of the capacitor C _5, and can use a low-voltage component , Leading to improved reliability. Another advantage of this embodiment is the same as the conventional configuration shown in FIG. 17, lower crest factor of the current supplied to the load L, and the lamp power factor is high, more is relatively small capacitance of the capacitor C ₅ And a smoothing capacitor C ₀
Since the charging current flows through the inverter circuit INV, almost no rush current occurs. Other configurations and operations are the same as those of the first embodiment.

[0066] (Embodiment 7) In this embodiment, in the conventional structure shown in FIG. 17, by performing the same conditions set the sixth embodiment is intended to determine the winding ratio of the transformer T _1. That, is replaced with a Taniuma circuit smoothing capacitor C ₀ for the embodiment 3 shown in FIG. That is, since the magnitude relation is reversed in Equation 8, it is possible to naturally obtain a conclusion.
2 will be obtained.

[0067]

(Equation 12)

By setting these conditions, a partial smoothing operation is always performed, and the same effects as in the sixth embodiment can be obtained. Further, similarly to Embodiment 3, a load by which using a little, also the transformer T ₁ is the power supply side and the load side by the transformer T ₁ is an electric shock when such attachment and detachment of the load L from the insulated It becomes easy to apply a high voltage to L. That is, if the load L is a discharge lamp, starting can be facilitated.

The load L may be a single discharge lamp, a plurality of discharge lamps may be connected in series, or a plurality of discharge lamps may be connected via a balancer transformer. (Embodiment 8) As shown in FIG.
Smoothing capacitor C ₀ in the configuration of the fourth embodiment shown in
And a configuration using a valley-filled circuit. The basic operation is the same as that of the conventional example shown in FIG. In this circuit configuration, the fact that satisfy formula 11, since it is possible to reverse the magnitude relationship in the equation 10, it is sufficient to set the winding ratio n of the transformer T ₁ as in equation 13.

[0070]

(Equation 13)

According to this condition setting, similarly to the sixth embodiment, the variation of the supply current to the load L is reduced, and the flicker due to the variation of the light output does not occur even when a discharge lamp is used for the load L in this embodiment. is there. Further, cost reduction is a voltage applied to the capacitor C ₅ because lower than the peak value of the rectifier circuit RE can be set relatively low withstand voltage of the capacitor C _5, and can use a low-voltage component , Leading to improved reliability. Embodiment 7
Similarly, it is possible to apply a high voltage to the load L by the transformer T _1, moreover electric shock is reduced by being insulated from the power supply side and load side by the transformer T ₁ and. Other configurations and operations are the same as those of the first embodiment.

[0072] (Embodiment 9) This embodiment in the configuration of embodiment 7, as shown in FIG. 7, is provided a tap in the primary winding of the transformer T _1, between the one end and the tap of the primary winding a is obtained by inserting the switch element S _1. That is, the main part of the fifth embodiment is applied to the seventh embodiment. Therefore, similarly to Embodiment 5, when reducing the output of the load L is keep off the switching element S _1, the load L
Turn on switching element S ₁ when increasing the output of.

In the present embodiment, even when a tap and a switch element S ₁ are provided on the secondary side of the transformer T ₁ , or when the output of the load L is switched even when the capacitor C ₂ is provided on the primary side, the condition of Expression 6 is satisfied. The effect of being able to satisfy can be achieved. Other configurations and operations are the same as those of the seventh embodiment. (Embodiment 10) In this embodiment, as shown in FIG.
In the conventional configuration shown in FIG. 17, attachment / detachment of the load L is detected, and when the load L is removed, the switching elements Q ₁ ,
The off Q ₂ 'is obtained by adding a configuration for controlling the control circuit CN to stop. Therefore, the basic condition setting is the same as in the seventh embodiment. Further, the load L in the present embodiment uses a discharge lamp DL.

[0074] configured to detect the detachment of the discharge lamp DL, the capacitor C ₇ inserted between one filament of the discharge lamp DL and the secondary winding of the transformer T _1, the capacitor C ₇
A series circuit of resistors R ₂ and R ₃ for voltage division, one end of which is connected to a connection point of the rectifier circuit RE, and a resistor R ₁ connected in parallel with a capacitor C ₂ , and a transformer T consisting connected resistors R ₄ Metropolitan between one end and the anode of the diode D ₀ is not connected to the capacitor C ₇ of the secondary winding of _1. In short, the DC circuit through both filaments of the discharge lamp DL is formed through the resistor R ₁ to R _4, when the discharge lamp DL has been removed, the attachment and detachment of the discharge lamp DL by using the fact that no current flows in the DC circuit Is detected. Whether or not a current is flowing through the DC circuit is detected based on the potential at the connection point between the resistors R ₂ and R ₃ .
When this potential becomes 0 V, it is determined that the discharge lamp DL has been removed. That is, the connection point of the resistors R ₂ and R ₃ is connected to the control bottleneck CN, and when the potential becomes 0 V, the control circuit CN stops the on / off operation of the switching element CN. As a result, it is possible to prevent an abnormal increase in the voltage across the smoothing capacitor C ₀ when there is no load.

As described above, it is necessary to form a DC circuit to detect the attachment / detachment of the discharge lamp DL.
Must be connected to the _first primary and secondary windings, the effect of the insulation by transformer T ₁ is impaired, the resistor R ₄ is inserted between the primary and secondary windings Thus, even if the discharge lamp DL being lit is touched, no electric shock is caused. That is, even current from the AC power supply AC flows through the human body when touched to the discharge lamp DL, than it is possible to reduce the current flowing through the human body by the resistance R ₄ is present in the current path .

Incidentally, the resistances R ₂ and R ₃ and the resistance R ₄ are set so as to satisfy the relationship of R ₄ ≒ R ₂ + R ₃ . Therefore, the ground side of the AC power supply AC (that is, the ground)
When viewed from above, the difference between the voltages applied to the filaments of the discharge lamp DL is reduced, and the gradient of the negative potential on the inner wall of the discharge lamp DL can be reduced. That is, the mercury sealed in the discharge lamp DL is localized on one end of the discharge lamp DL on the side where the negative charge is large (so-called cataphoresis).
Although the brightness at the other end is reduced, this kind of phenomenon does not occur. Other configurations and operations are described in Embodiment 7.
Is the same as

[0077] (Embodiment 11) This embodiment, as shown in FIG. 11, the power winding provided to the inductor L _1, the inductor L ₁ of the power winding one end of the DC output ends of the rectifier circuit RE as well as connected to the negative electrode, the output voltage of the power winding by the diode D ₅ and the resistor R ₅ and capacitor C ₈ by rectifying and smoothing the voltage across the resistor R ₁ to R of the capacitor C _8
This is used for the power supply of the DC circuit composed of ₄ . Thus, one end of the resistor R ₄ is not a anode of the diode D _0, is connected to a connection point between the capacitor C ₈ and the resistor R _5.

In this configuration, since the primary side and the secondary side of the transformer T ₁ are insulated from each other, there is no danger of electric shock even if a person touches the load L as in the seventh embodiment. The attachment / detachment can be detected based on the potential at the connection point between the resistors R ₂ and R ₃ . Other configurations and operations are the same as those of the seventh embodiment. In the configuration example described above is provided with the power winding to the inductor L _1, but the transformer T ₁
A power supply winding may be provided, and the output of the winding may be rectified and smoothed to obtain a power supply for a DC circuit by the resistors R _{1 to} R ₄ .

[0079]

According to the first to thirteenth aspects of the present invention, an inverter circuit having an impedance circuit between a rectifier circuit and a smoothing capacitor and having a resonance circuit including a load is provided. Since the circuit constants are set so that the relationship between the peak value of the current and the effective value of the current flowing through the resonance circuit is a predetermined relationship, the input current distortion is small and the variation of the supply current to the load is reduced by this relationship. There is an advantage that it is possible to make the number relatively small.

According to the first to fifth aspects of the present invention, the current flowing in the resonance circuit changes in response to the pulsating waveform of the output voltage of the rectifier circuit, but the current is adjusted by adjusting the switching frequency for turning on and off the switching element. Since the change can be easily suppressed, the fluctuation of the supply current to the load can be suppressed. For example, if the load is a discharge lamp, fluctuations in light output can be suppressed and flicker-free illumination light can be obtained.

In the configurations of claims 6 to 11, since the crest factor of the current supplied to the load is small, the fluctuation of the current supplied to the load is small without changing the switching frequency for turning on and off the switching element. In addition, the power factor of the power supplied to the load is relatively high. Further, since the voltage applied to the valley filling circuit is relatively low, a component having a low withstand voltage can be used as a component.

According to the eleventh aspect of the present invention, since the switching element of the inverter circuit is interposed in the charging path to the smoothing capacitor, the generation of the rush current due to the charging current flowing directly from the rectifier circuit to the smoothing capacitor can be suppressed. it can. The invention of claim 12 and claim 13 is:
A DC circuit is formed on the path that passes through the filament with the load as the discharge lamp, and when the discharge lamp is removed, the switching element is controlled to be kept off. There is an advantage that generation can be prevented. Moreover, claim 12
In the configuration of (1), a fourth resistor is inserted between the primary side and the secondary side of the transformer, and in the configuration of (13), a power supply to the DC circuit is supplied from a power supply winding provided on one of the inductor and the transformer. Therefore, a resistor is inserted or insulated between the AC power supply and the discharge lamp, and as a result, almost no current flows to the human body even if the discharge lamp is touched during energization, There is an advantage that electric shock can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is an operation explanatory diagram showing the first embodiment.

FIG. 3 is a circuit diagram showing a second embodiment.

FIG. 4 is a circuit diagram showing a third embodiment.

FIG. 5 is a main part circuit diagram showing a modification of the third embodiment.

FIG. 6 is a circuit diagram showing a fourth embodiment.

FIG. 7 is a main part circuit diagram showing Embodiments 5 and 9;

FIG. 8 is a circuit diagram showing a sixth embodiment.

FIG. 9 is a circuit diagram showing an eighth embodiment.

FIG. 10 is a circuit diagram showing a tenth embodiment.

FIG. 11 is a circuit diagram showing an eleventh embodiment.

FIG. 12 is a circuit diagram showing a conventional example.

FIG. 13 is an explanatory diagram of the operation of the above.

FIG. 14 is an operation explanatory view of the above.

FIG. 15 is an explanatory diagram of the operation of the above.

FIG. 16 is an operation explanatory diagram showing the above problem.

FIG. 17 is a circuit diagram showing another conventional example.

FIG. 18 is an operation explanatory view of the above.

FIG. 19 is an operation explanatory diagram showing the above problem.

[Explanation of symbols]

A resonant circuit AC AC power supply C ₀ smoothing capacitor C ₁ capacitor C ₂ capacitors C ₃ capacitor C ₄ capacitors C ₇ capacitor C ₈ capacitor CN control circuit D ₀ diode D ₁ diode D ₂ diodes D ₃ diode D ₅ diodes DL discharge lamp INV inverter circuit L the load L ₁ inductor L ₂ inductor R ₁ resistor R ₂ resistor R ₃ resistor R ₄ resistor RE rectifier circuit Q ₁ switching element Q ₂ switching element S ₁ switch elements T ₁ trans Z-impedance circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsunobu Hamamoto, Inventor 1048, Kazuma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. Inside

Claims (13)

[Claims] A rectifier circuit for rectifying an AC power supply, and an inverter circuit for converting an output of the rectifier circuit into a high-frequency output and supplying the output to a load, wherein the inverter circuits are connected in series with each other and alternately turned on and off. A switching element, an impedance circuit interposed between the DC output terminal of the rectifier circuit and the series circuit of both switching elements, and a series circuit of the impedance circuit including a capacitor and an inductor. A resonance circuit connected between the power supply and the output circuit, and a smoothing capacitor connected in parallel to the series circuit of the two switching elements, and an effective value of a current flowing through the resonance circuit is supplied from the AC power supply to the rectifier circuit. A power supply device wherein a circuit constant is set so as to be twice or more a peak value of an input current. 2. A rectifier circuit comprising a diode bridge, wherein a capacitor is connected between a DC output terminal of the rectifier circuit and a diode is inserted between the DC output terminal of the rectifier circuit and the inverter circuit in a forward direction. The power supply device according to claim 1, wherein: 3. The resonance circuit includes a first capacitor for cutting DC, an inductor and a second capacitor for resonance, a load connected to a secondary side, and a primary winding having the first capacitor and the inductor. The second capacitor is connected in parallel with the load, and the effective value of the current flowing through the resonance circuit is twice or more the peak value of the input current from the AC power supply to the rectifier circuit. 2. The power supply device according to claim 1, wherein a turn ratio of the transformer is set in the power supply. 4. The resonance circuit includes a first capacitor for cutting DC, an inductor and a second capacitor for resonance, a load connected to a secondary side, and a primary winding having the first capacitor and the inductor. A second capacitor is connected between both ends of a primary winding of the transformer, and an effective value of a current flowing through the resonance circuit is a peak value of an input current from the AC power supply to the rectifier circuit. 2. The power supply device according to claim 1, wherein the turns ratio of the transformer is set to be at least twice as large as that of the transformer. 5. The resonance circuit includes a transformer having a load connected to a secondary side, a tap provided on at least one of a primary winding and a secondary winding of the transformer, and a winding of the winding provided with the tap. A switch element that opens and closes according to the output to the load is provided between one end and the tap, and the effective value of the current flowing through the resonance circuit is at least twice the peak value of the input current from the AC power supply to the rectifier circuit. 2. The power supply device according to claim 1, wherein the turns ratio of the transformer and the position of the tap are set as described above. 6. A rectifier circuit for rectifying an AC power supply, and an inverter circuit for converting an output of the rectifier circuit to a high-frequency output and supplying the output to a load, wherein the inverter circuits are connected in series with each other and alternately turned on and off. A switching element, an impedance circuit interposed between the DC output terminal of the rectifier circuit and the series circuit of both switching elements, and a series circuit of the impedance circuit including a capacitor and an inductor. A switching circuit connected between the resonant circuit for taking out the output to the load and a part of the output of the inverter circuit during a high period of the DC output voltage of the rectifier circuit and a voltage determined by the stored energy during a low period of time. And a valley-filled circuit applied to both ends of the series circuit, wherein the effective value of the current flowing through the resonance circuit is A power supply device wherein a circuit constant is set so as to be equal to or less than twice a peak value of an input current to a rectifier circuit. 7. A rectifier circuit comprising a diode bridge, wherein a capacitor is connected between a DC output terminal of the rectifier circuit and a diode is inserted between the DC output terminal of the rectifier circuit and the inverter circuit in a forward direction. The power supply device according to claim 6, wherein: 8. The resonance circuit includes a first capacitor for cutting DC, an inductor and a second capacitor for resonance, a load connected to a secondary side, and a primary winding having the first capacitor and the inductor. The second capacitor is connected in parallel to the load, and the effective value of the current flowing through the resonance circuit is less than twice the peak value of the input current from the AC power supply to the rectifier circuit. 7. The power supply device according to claim 6, wherein a turn ratio of the transformer is set in the power supply. 9. The resonance circuit includes a first capacitor for cutting DC, an inductor and a second capacitor for resonance, a load connected to a secondary side, and a primary winding having the first capacitor and the inductor. A second capacitor is connected between both ends of a primary winding of the transformer, and an effective value of a current flowing through the resonance circuit is a peak value of an input current from the AC power supply to the rectifier circuit. 7. The power supply device according to claim 6, wherein the turns ratio of the transformer is set so as to be twice or less of the following. 10. The resonance circuit includes a transformer having a load connected to a secondary side, a tap provided in at least one of a primary winding and a secondary winding of the transformer, and a tap winding provided with a tap. A switch element that is opened and closed according to the output to the load is provided between one end and the tap, and the effective value of the current flowing through the resonance circuit is less than twice the peak value of the input current from the AC power supply to the rectifier circuit. 7. The power supply device according to claim 6, wherein the turns ratio of the transformer and the position of the tap are set as described above. 11. The valley filling circuit includes a smoothing capacitor connected between a DC output terminal of a rectifier circuit via one switching element, and the smoothing capacitor is charged when the switching element is turned on. The power supply device according to claim 6. 12. A load is a discharge lamp having a filament, wherein the resonance circuit includes a transformer having a secondary winding connected to the discharge lamp via a DC blocking capacitor, and connected between a non-power supply end of the filament. A second resistor and a second resistor for voltage division inserted between a power supply side end of one filament and a negative electrode of a DC output terminal of the rectifier circuit;
A fourth resistor inserted between a power supply side of the other filament and one end of a primary winding of a transformer which is a positive side of a DC output terminal of the rectifier circuit, and a connection point of the second and third resistors; The power supply device according to claim 1, further comprising a control circuit configured to control so as to keep the switching element off when a no-load is detected based on the potential. 13. The load is a discharge lamp having a filament, wherein the resonance circuit includes a transformer having a secondary winding connected to the discharge lamp via a DC blocking capacitor, and connected between non-power supply terminals of the filament. A second resistor and a third resistor for voltage division inserted between a power supply side end of one of the filaments and a negative electrode of a DC output terminal of the rectifier circuit;
Means for rectifying and smoothing the voltage at both ends of a power supply winding provided at one of the inductor and the transformer and having one end connected to the negative electrode of the dc output terminal of the rectifier circuit to obtain a dc power supply; A fourth resistor inserted between the first and second DC power supplies, and a control circuit for controlling the switching element to be kept off when no load is detected based on the potential at the connection point of the second and third resistors. The power supply device according to claim 1 or 6, wherein: