JPH11164571A - Power supply equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an input distortion and a crest factor, by connecting an input section including a full-wave rectifier to a connection between a diode and a capacitor through an impedance. SOLUTION: An input AC power supply Vs is connected with a filter circuit constituted of a capacitor Cf, a transformer Tf, and an inductance Lf as an impedance Z, which is connected with a series circuit of a capacitor C5 and a diode. To both terminals of the capacitor C5, AC input terminals of a full- wave rectifier DB constituted of a diode bridge are connected. Input current led from the AC power supply Vs through the filter circuit Z is supplied to the power supply equipment X together with electric charge accumulated in the capacitor C5. To the capacitor C5, charging current is supplied from the AC power supply in the remaining four stages. By this method, a freedom of design is expanded and, when instantaneous voltage of the AC power supply is small, input current increases, thereby eliminating an input distortion and a crest factor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a DC voltage obtained by rectifying and smoothing an AC power supply to a high frequency and supplying it to a load.

[0002]

2. Description of the Related Art FIG. 15 shows a conventional example (JP-A-5-38161).
FIG. This circuit converts a DC voltage obtained by rectifying and smoothing the AC power supply Vs into a high frequency and supplies the high frequency to a load. In addition, a high frequency current flows from the AC power supply Vs via a filter circuit F, thereby improving input current waveform distortion. It has the function of rate improvement. Hereinafter, the circuit configuration will be described. Full-wave rectifier D consisting of a diode bridge
An AC power supply Vs is connected between the AC input terminals B through a filter circuit F. The filter circuit F includes a capacitor, a transformer, an inductor, and the like, and functions as a low-pass filter that prevents a high-frequency current from flowing to the AC power supply Vs. The anode of the diode D3 is connected to the positive electrode side of the DC output terminal of the full-wave rectifier DB, and the cathode of the diode D3 is connected to the positive electrode of the smoothing capacitor C1. The negative electrode of the smoothing capacitor C1 is
It is connected to the negative side of the DC output terminal of the full-wave rectifier DB. A capacitor C3 for improving input distortion is connected in parallel to both ends of the diode D1. Smoothing capacitor C1
, A series circuit of switching elements Q1 and Q2 is connected in parallel. A coupling capacitor C2 for cutting a DC component is provided between the connection point of the switching elements Q1 and Q2 and the positive side of the DC output terminal of the full-wave rectifier DB.
, A primary winding of the transformer T1, and an inductor L for resonance.
1 and a discharge lamp LA as a load is connected to the secondary winding of the transformer T1.
A resonance capacitor C4, which also serves as a preheating current passage, is connected in parallel between the non-power supply terminals of the filament of the discharge lamp LA. Inductor L1 and capacitor C4 are LC
A series resonance circuit is configured. When the transformer T1 is a leakage transformer, its leakage inductance may be used as the inductor L1.

Next, the operation of the circuit shown in FIG. 15 will be described with reference to FIG.
(C) and FIGS. 17 (d) to (f).
However, in FIGS. 16 and 17, the switching elements Q1 and Q2 formed by MOSFETs in the circuit of FIG.
Are respectively connected to transistors Q1, Q2 and diode D1,
D2 is represented by a parallel circuit. The transformer T1 is a leakage transformer, and the inductor L1 in FIG. 15 is omitted. Further, the filter circuit is divided into blocks to simplify the illustration. 16 and 17A to FIG.
(F) shows six stages in one cycle of the high frequency amplitude of the circuit of FIG. First, FIG.
In the stage 1 shown in (1), the switching element Q2 is in the ON state, and a current flows from the smoothing capacitor C1 through the path of the input distortion improving capacitor C3, the coupling capacitor C2, the leakage transformer T1, the switching element Q2, and the smoothing capacitor C1. Thus, a charging current flows from the smoothing capacitor C1 to the input distortion improving capacitor C3.

Next, in stage 2 shown in FIG. 16 (b), the potential Va (the output voltage of the full-wave rectifier DB) at the connection point between the coupling capacitor C2 and the diode D1 changes the potential of the input AC power supply Vs to a filter circuit. When the voltage becomes equal to the filtered voltage Vb, a resonance current flows from the input AC power supply Vs via the leakage transformer T1. That is, the AC power supply Vs, the filter circuit F, the full-wave rectifier D
An input current flows through the path of B, the coupling capacitor C2, the leakage transformer T1, the switching element Q2, and the full-wave rectifier DB.

Next, in the stage 3 shown in FIG. 16C, the switching element Q2 is turned off and the switching element Q
1 turns on, and a resonance current flows as shown in the figure. That is,
A leakage transformer T1, a diode D1 (a reverse conducting element of the switching element Q1), a smoothing capacitor C1,
A regenerative current flows through the path of the full-wave rectifier DB, the filter circuit F, the AC power supply Vs, the filter circuit F, the full-wave rectifier DB, the coupling capacitor C2, and the leakage transformer T1.

Next, in the stage 4 shown in FIG. 17D, the resonance current is commutated as shown in the figure, and the input distortion improving capacitor C3 is discharged. That is, the leakage transformer T1, the coupling capacitor C2, and the capacitor C
3, a current flows through the path of the switching element Q1 and the leakage transformer T1, and the capacitor C3 is discharged. Next, in the stage 5 shown in FIG. 17E, after the input distortion improving capacitor C3 is discharged, a resonance current flows through the diode D1. That is, the leakage transformer T1, the coupling capacitor C2, and the diode D
3. A current flows through the path of the switching element Q1 and the leakage transformer T1.

Next, in stage 6 shown in FIG. 17F, switching element Q1 is turned off and switching element Q
2 turns on, and a resonance current flows as shown in the figure. That is,
Leakage transformer T1, coupling capacitor C
2, a current flows through the path of the diode D3, the smoothing capacitor C1, the diode D2 (the reverse conducting element of the switching element Q2), and the leakage transformer T1.

The above six stages are repeated with the charge / discharge cycle of the input distortion improving capacitor C2. Here, the stage 2 (FIG. 16B) and the stage 3
The input current flows from the AC power supply Vs during (FIG. 16 (c)), and the input current becomes sinusoidal by changing the time length of the six stages according to the magnitude of the input voltage, thereby increasing the input power factor. .

[0009]

In the conventional example shown in FIG. 15, the current oscillation of the resonance current is used so that the input power factor can be increased by using the charging and discharging of the input distortion improving capacitor C3. . Generally, the degree of input distortion or crest factor differs depending on the circuit constant and the oscillation frequency, and in order to satisfy both of them, separately-excited control that modulates the switching operation according to the instantaneous voltage of the AC power supply Vs is used. I have. However, in order to reduce costs, it is desirable to perform self-excited control.

In the conventional example shown in FIG. 15, when self-excited control is performed, the circuit operates as described in the conventional example. Therefore, the input distortion improving capacitor C3 is connected to the resonance system according to the instantaneous voltage of the AC power supply Vs. , The frequency of self-excited oscillation changes according to the instantaneous voltage of the AC power supply Vs, thereby changing input distortion and crest factor. Therefore, in order to design the circuit by the self-excited control, the resonance constant, the constant of the input distortion improving capacitor C3, and the like are considered in consideration of the fact that the frequency of the self-excited oscillation changes according to the instantaneous voltage of the AC power supply Vs. It is necessary to design, and there is a problem that the degree of freedom of design is considerably reduced depending on the load.

In the above conventional example, where the instantaneous voltage of the AC power supply Vs is small, the capacitor C3 for improving input distortion operates in series with the resonance system, so that the frequency of self-excited oscillation increases and the resonance current increases. Becomes smaller. In addition, there is also a problem that a voltage effect of a filter or the like causes a reduction in the amount of input current drawn where the instantaneous voltage of the AC power supply Vs is small, thereby causing a pause period of the input current and deteriorating input distortion. For example, in the case of a separately-excited control method, the degree of freedom in designing the value of the input distortion improving capacitor C3, the oscillation frequency, the modulation control, and the like is large. Therefore, even if the input filter is designed freely, an input current waveform as shown in FIG. 18B can be obtained with respect to the input voltage shown in FIG. However, if the self-excited control method is used as it is, the input waveform becomes as shown in FIG. 18C, and the input distortion is deteriorated.

The present invention has been made to solve the above-mentioned problems. The present invention is directed to a method of controlling an inverter, which is an inexpensive self-excited control method utilizing a current or a voltage generated in a load resonance circuit, while reducing input distortion and crest factor. It proposes a circuit system that satisfies both.

[0013]

According to the present invention, in order to solve the above-mentioned problem, as shown in FIG. 1, in a power supply device X having a conventional circuit configuration, a series circuit of a diode D4 and a capacitor C5 is provided at an input portion. By connecting an input unit including a full-wave rectifier DB for rectifying the AC power supply Vs to the connection point of the diode D4 and the capacitor C5 via the impedance Z, thereby increasing the degree of freedom of the self-excitation control design. Expand
An input current waveform as shown in FIG. 18B is used to improve input distortion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first basic configuration diagram of the present invention.
Shown in The configuration of the power supply device X is the same as that of the conventional example shown in FIG. 15. As described in the conventional example, a high-frequency resonance current is generated, and the input current is supplied from the AC power supply Vs in two of the six stages. Pull in. In this embodiment, a series circuit of a diode D4 and a capacitor C5 is connected to the input side of the power supply device X. In the above two stages, the input current from the AC power supply Vs together with the electric charge accumulated in the capacitor C5 and the inductor L2 Is supplied to the power supply device X via the. The capacitor C5 is supplied with a charging current from the AC power supply Vs in the remaining four stages. Therefore, when viewed from the input side, the impedance Z performs an operation of charging the capacitor C5 in a DC manner, and the power supply device X
When viewed from the side, the impedance component on the input side is increased in high frequency. Therefore, in a device such as the power supply device X that performs an operation including the current path on the input side during one cycle of the operation of the resonance current, the resonance of the capacitor C5 is not affected by the circuit constant on the input side. Since the operation is determined, the operation of the self-excited oscillation is easy to design. That is, the degree of freedom in design is increased. When the voltage of the AC power supply Vs is low, the charge accumulated in the capacitor C5 is drawn in as input current in the two stages for drawing the input current, and the input current is drawn in the remaining four stages as the charging current to the capacitor C5. Therefore, the input current when the voltage of the AC power supply Vs is small increases and the input distortion is improved as compared with the conventional example in which the input current is drawn through the impedance of a filter or the like only by the two stages for drawing the input current. You.

In the second basic configuration diagram shown in FIG.
The impedance Z and the capacitor C5 are arranged on the input side of the full-wave rectifier DB, and the full-wave rectifier DB and the diode D4
The following shows the case where both are used. In this case, the same effect as described above is obtained.

The capacitor C5 is used for switching 1
It is desirable that the capacity be small enough to charge and discharge charges within a cycle. Similar results can be obtained by using an inductor or a resistor as the impedance Z. Hereinafter, specific examples will be described.

[0017]

(Embodiment 1) FIG. 3 is a specific circuit diagram of Embodiment 1 of the present invention. Hereinafter, the circuit configuration will be described.
The input AC power supply Vs includes a capacitor Cf and a transformer Tf.
A filter circuit including an inductor Lf is connected as an impedance Z, and a series circuit of a capacitor C5 is connected to the filter circuit Z. An AC input terminal of a full-wave rectifier DB formed of a diode bridge is connected to both ends of the capacitor C5. The anode of the diode D3 is connected to the positive electrode side of the DC output terminal of the full-wave rectifier DB, and the cathode of the diode D3 is connected to the positive electrode of the smoothing capacitor C1. The negative electrode of the smoothing capacitor C1 is connected to the negative side of the DC output terminal of the full-wave rectifier DB. A capacitor C3 for improving input distortion is connected in parallel to both ends of the diode D3. At both ends of the smoothing capacitor C1, a series circuit of switching elements Q1 and Q2 formed of MOSFETs is connected in parallel. A coupling capacitor C2 for cutting a DC component, a primary winding of a leakage transformer T1, and a current feedback between a connection point of the switching elements Q1 and Q2 and a positive side of a DC output terminal of the full-wave rectifier DB. Is connected to a series circuit of a primary winding of a self-excited driving transformer T2, and a discharge lamp L as a load is connected to a secondary winding of the leakage transformer T1.
A is connected, and a resonance capacitor C4, which also serves as a preheating current conduction path, is connected in parallel between the non-power supply terminals of the filament of the discharge lamp LA. The leakage inductance of leakage transformer T1 and capacitor C4 are LC
A series resonance circuit is configured.

A pair of secondary windings of the self-excited drive transformer T2 are connected between the gates and sources of the switching elements Q1 and Q2 via low resistances. Since the secondary windings of the self-excited driving transformer T2 are connected to have opposite polarities, the switching elements Q1 and Q2 are alternately switched due to the inversion of the resonance current flowing through the primary winding of the self-excited driving transformer T2. Performs self-excited oscillation operation that turns on and off. A protection circuit in which a pair of zener diodes are connected in series in the opposite direction is connected in parallel between the gate and source of each of the switching elements Q1 and Q2.

Next, a starting circuit for the self-excited oscillation operation will be described. Resistors R3 and R3 are connected to both ends of the smoothing capacitor C1.
The capacitor C7 is connected via a series circuit of R4 and R5. The connection point between the capacitor C7 and the resistor R5 is connected to the gate of the switching device Q2 via a trigger element Qt such as a diac, and is connected to the drain of the switching device Q2 via a diode D7 and a resistor R6.

The operation of this starting circuit is well known,
After the power is turned on, when the voltage of the smoothing capacitor C1 rises,
When the capacitor C7 is charged via the resistors R3, R4 and R5 and the charged voltage reaches or exceeds the breakover voltage of the trigger element Qt, the trigger element Qt is turned on and the charge of the capacitor C7 is changed to the gate of the switching element Q2. -Discharge occurs between the sources, and the switching element Q2 turns on. Thereby, the capacitor C2, the leakage transformer T1, the self-excited drive transformer T2, the switching element Q
2, a current flows through the self-excited drive transformer T2 due to the resonance of the inductance of the leakage transformer T1 and the capacitor C4. As a result, a drive signal is applied from the secondary winding of the self-excited drive transformer T2 between the gate and source of the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are turned on and off alternately. When the switching element Q2 is turned on at a high frequency, the electric charge of the capacitor C7 becomes the diode D7 and the resistance R
6. Since the discharge is performed via the switching element Q2, the start-up circuit stops operating.

Next, the operation of the circuit of this embodiment after the start is shown in FIG.
This will be described with reference to (a) to (c) and FIGS. 5 (d) to (f). However, in FIGS. 4 and 5, M in the circuit of FIG.
The switching elements Q1 and Q2 constituted by OSFETs are respectively connected to transistors Q1 and Q2 and diodes D1 and D2.
It is expressed by two parallel circuits. The self-excited windings of the switching elements Q1 and Q2 are not shown. FIGS. 4A to 5F show six stages in one cycle of the high-frequency amplitude of the circuit of FIG. First, in the stage 1 shown in FIG. 4A, the switching element Q2 is in an ON state, and a charging current flows from the smoothing capacitor C1 to the input distortion improving capacitor C3.
At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in stage 2 shown in FIG. 6B, the potential V at the connection point between the capacitor C2 and the diode D3 is set.
When a (the output voltage of the full-wave rectifier DB) becomes equal to the potential of the capacitor C5, a resonance current flows from the input power supply Vs via the leakage transformer T1. At the same time, the capacitor C5 is discharged.

Next, in the stage 3 shown in FIG. 4C, the switching element Q1 is turned on, the resonance current flows as shown, and the resonance current I _T1 decreases. At the same time, the capacitor C5 is discharged. Next, in the stage 4 shown in FIG. 5D, the resonance current commutates as shown in the figure, and the input distortion improving capacitor C3 is discharged. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z. Next, in stage 5 shown in FIG.
After the input distortion improving capacitor C3 is discharged, a resonance current flows through the diode D3. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z. Next, in the stage 6 shown in FIG. 5F, the switching element Q2 is turned on, and a resonance current flows as shown in the figure. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

In this embodiment, since the series circuit of the diode D1 and the capacitor C5 is provided on the input side of the power supply device X, the filter circuit Z is switched from the AC power supply Vs in the two stages for drawing the input current. The input current drawn through is supplied to the power supply device X together with the electric charge stored in the capacitor C5. The capacitor C5
, A charging current is supplied from the AC power supply Vs in the remaining four stages. Therefore, even when the instantaneous voltage of the AC power supply Vs is small, the input current increases, and even if the operation frequency increases when the input voltage specific to the self-excited circuit is small, the input distortion does not deteriorate. At the same time, since the self-excited oscillation frequency can be adjusted by the capacitance of the capacitor C5, the degree of freedom in design increases. Thus, the power supply X
The arrangement of the series circuit of the diode D1 and the capacitor C5 and the impedance Z on the input side increases the degree of freedom of design in the self-excitation control method, and increases the input current when the instantaneous voltage of the AC power supply Vs is small. In addition, the input distortion is improved.

Although the self-excited drive transformer T2 is used in FIG. 3, as shown in FIG. 6, even when the self-excited drive transformer T2 and the leakage transformer T1 are used, the same operation is performed, and the same effect is obtained. It goes without saying that you can get it.

(Embodiment 2) FIG. 7 is a specific circuit diagram of Embodiment 2 of the present invention. Hereinafter, the circuit configuration will be described. A filter circuit including a capacitor Cf, a transformer Tf, and an inductor Lf is connected as an impedance Z to the input AC power supply Vs.
Is connected to a capacitor C5. Capacitor C5
, A full-wave rectifier D composed of a diode bridge
B AC input terminal is connected. A capacitor C3 for improving input distortion is connected to both ends of the DC output terminal of the full-wave rectifier DB. The negative electrode of the smoothing capacitor C1 is
It is connected to the negative side of the DC output terminal of the full-wave rectifier DB. At both ends of the smoothing capacitor C1, a series circuit of switching elements Q1 and Q2 formed of MOSFETs is connected in parallel. The primary winding of the leakage transformer T1 and the primary winding of the self-excited drive transformer T2 for current feedback are provided between the connection point of the switching elements Q1 and Q2 and the positive side of the DC output terminal of the full-wave rectifier DB. The discharge lamp LA as a load is connected to the secondary winding of the leakage transformer T1, and a preheating current supply path is provided between the non-power-supply-side terminals of the filament of the discharge lamp LA. Are connected in parallel. The leakage inductance of the leakage transformer T1 and the capacitor C4 constitute an LC series resonance circuit.

A pair of secondary windings of the self-excited driving transformer T2 are connected between the gates and sources of the switching elements Q1 and Q2 via low resistances. Since the secondary windings of the self-excited driving transformer T2 are connected to have opposite polarities, the switching elements Q1 and Q2 are alternately switched due to the inversion of the resonance current flowing through the primary winding of the self-excited driving transformer T2. Performs self-excited oscillation operation that turns on and off. A protection circuit in which a pair of zener diodes are connected in series in the opposite direction is connected in parallel between the gate and source of each of the switching elements Q1 and Q2.

The configuration of the starting circuit is the same as that of the first embodiment, and is composed of resistors R3 to R6, a capacitor C7, a diode D7, and a trigger element Qt, and operates in the same manner as the first embodiment. However, in this embodiment, after the power is turned on, the voltage of the smoothing capacitor C1 increases due to the current flowing through the reverse diode incorporated in the switching element Q1, and thereafter, the smoothing is performed by the boosting chopper operation by the switching element of the switching element Q2. The voltage of the capacitor C1 is boosted.

Next, the operation of the circuit of this embodiment after the start-up will be described with reference to FIG.
This will be described with reference to FIGS. 9A and 9B and FIGS. However, in FIGS. 8 and 9, M in the circuit of FIG.
The switching elements Q1 and Q2 constituted by OSFETs are respectively connected to transistors Q1 and Q2 and diodes D1 and D2.
It is expressed by two parallel circuits. The self-excited windings of the switching elements Q1 and Q2 are not shown. FIGS. 8A to 9E show five stages in one cycle of the high-frequency amplitude of the circuit of FIG. First, in the stage 1 shown in FIG. 8A, the switching element Q1 is in an ON state, and a charging current flows from the smoothing capacitor C1 to the input distortion improving capacitor C3 via the switching element Q1 and the leakage transformer T1. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in stage 2 shown in FIG. 8B, the switching element Q1 is turned off and the switching element Q
2 turns on, and a resonance current flows as shown in the figure. That is,
A regenerative current flows through a path that passes through the leakage transformer T1, the capacitor C3, and the diode D2 (a reverse-direction energizing element of the switching element Q2). At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in the stage 3 shown in FIG. 8C, the resonance current is commutated as shown in the figure, and the input distortion improving capacitor C3 is discharged. That is, the capacitor C3,
A current flows through a path that passes through the leakage transformer T1 and the switching element Q2. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in stage 4 shown in FIG. 9D, when the potential Va (the output voltage of the full-wave rectifier DB) at the connection point between the capacitor C3 and the leakage transformer T1 becomes equal to the potential of the capacitor C5, the input AC A resonance current flows from the power supply Vs via the leakage transformer T1. That is, the inductor L1, the full-wave rectifier D
B, leakage transformer T1, switching element Q2,
A current flows through the path of the full-wave rectifier DB and the AC power supply Vs.
At the same time, the capacitor C5 is discharged.

Next, in the stage 5 shown in FIG. 9E, the switching element Q1 is turned on and the switching element Q
2 is turned off, and the resonance current flows as shown in the figure. That is, the inductor L2 and the full-wave rectifier D
B, leakage transformer T1, diode D1 (reverse conducting element of switching element Q1), smoothing capacitor C
1. A current flows through the path of the full-wave rectifier DB and the AC power supply Vs. At the same time, the capacitor C5 is discharged.

In this embodiment, since the series circuit of the diode D1 and the capacitor C5 is provided on the input side of the power supply device X, the filter circuit Z is switched from the AC power supply Vs in the two stages for drawing the input current. The input current drawn through is supplied to the power supply device X together with the electric charge stored in the capacitor C5. The capacitor C5
, A charging current is supplied from the AC power supply Vs in the remaining three stages. Therefore, even when the instantaneous voltage of the AC power supply Vs is small, the input current increases, and even if the operation frequency increases when the input voltage specific to the self-excited circuit is small, the input distortion does not deteriorate. At the same time, since the self-excited oscillation frequency can be adjusted by the capacitance of the capacitor C5, the degree of freedom in design increases. Thus, the power supply X
The arrangement of the series circuit of the diode D1 and the capacitor C5 and the impedance Z on the input side increases the degree of freedom of design in the self-excitation control method, and increases the input current when the instantaneous voltage of the AC power supply Vs is small. In addition, the input distortion is improved.

Although the self-excited drive transformer T2 is used in FIG. 7, the self-excited drive transformer T2 is used as shown in FIG.
It is needless to say that the same operation is obtained even when the leakage transformer T1 is also used and the same effect is obtained.

(Embodiment 3) FIG. 11 shows a specific circuit diagram of Embodiment 3 of the present invention. Hereinafter, the circuit configuration will be described. A filter circuit including a capacitor Cf, a transformer Tf, and an inductor Lf is connected as an impedance Z to the input AC power supply Vs.
Is connected to a capacitor C5. Capacitor C5
Is connected to the anode of the diode D5 and the diode D6.
The other end of the capacitor C5 is connected to one end of the capacitor C3. The cathode of the diode D5 is connected to the positive electrode of the smoothing capacitor C1, and the anode of the diode D6 is connected to the negative electrode of the smoothing capacitor C1 and to the other end of the capacitor C3. At both ends of the smoothing capacitor C1, M
A series circuit of switching elements Q1 and Q2 composed of OSFETs is connected in parallel. Switching elements Q1, Q
2, a series circuit of a primary winding of the leakage transformer T1 and a primary winding of the self-excited drive transformer T2 for current feedback is connected between the connection point of the capacitors C3 and C5. The discharge lamp LA as a load is connected to the secondary winding of the leakage transformer T1, and the discharge lamp LA
A resonance capacitor C4, which also serves as a preheating current conduction path, is connected in parallel between the non-power supply terminals of the filament. The leakage inductance of the leakage transformer T1 and the capacitor C4 constitute an LC series resonance circuit.

The pair of secondary windings of the self-excited drive transformer T2 are connected to the switching element Q via low resistances R1 and R2, respectively.
1, Q2 are connected between the gate and source. Since the respective secondary windings of the self-excited driving transformer T2 are connected to have opposite polarities, the switching elements Q1, Q2 are inverted by reversing the resonance current flowing through the primary winding of the self-excited driving transformer T2.
2 performs a self-excited oscillation operation that alternately turns on and off. In addition,
A protection circuit in which a pair of zener diodes are connected in series in the opposite direction is connected in parallel between the gate and source of each of the switching elements Q1 and Q2.

The configuration of the starting circuit is the same as that of the first embodiment, and is composed of resistors R3 to R6, a capacitor C7, a diode D7, and a trigger element Qt, and operates in the same manner as the first embodiment. The switching elements Q1 and Q2 are alternately turned on and off at a high frequency by the self-excited oscillation operation, thereby supplying high-frequency power to the load LA.

Next, the operation of the circuit of this embodiment after starting up will be described with reference to FIG.
2 (a) to 2 (c) and FIGS. 13 (d) and 13 (e). However, in FIGS. 12 and 13, the switching element Q composed of MOSFET in the circuit of FIG.
1 and Q2 are represented by parallel circuits of transistors Q1 and Q2 and diodes D1 and D2, respectively. Further, the load circuit including the series resonance circuit including the leakage transformer T1 and the resonance capacitor C4 is blocked to simplify the drawing. The self-excited windings of the switching elements Q1 and Q2 are not shown. (A) to (e) of FIG. 12 and FIG.
12 shows five stages in a high frequency amplitude one cycle of the circuit of FIG. It is assumed that the AC power supply Vs is positive in the directions shown in FIGS.

First, in the stage 1 shown in FIG. 12A, the switching element Q1 is turned on and the switching element Q
2 is turned off, and the load circuit A and the diode D
A current flows through a path of 1 (a reverse conduction element of the switching element Q1), the capacitor C1, the capacitor C3, and the load circuit. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in stage 2 shown in FIG. 12B, when all the energy stored in the load circuit A is released, the capacitor C1 is used as a power source, as shown in FIG. A current flows through the path of the load circuit A, the capacitor C3, and the capacitor C1, and power is supplied to the load. At this time, the voltage of the capacitor C3 gradually increases. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z.

Next, in the stage 3 shown in FIG. 12C, when the voltage of the capacitor C3 becomes equal to the voltage of the capacitor C5, no more current flows into the capacitor C3. However, since current still flows in the same direction in the load circuit A, as shown in the figure,
AC power supply Vs, diode D5, switching element Q
1. Load circuit A, path of AC power supply Vs, or capacitor C5, diode D5, switching element Q1,
A current flows through the path of the load circuit A and the capacitor C5.
At the same time, the capacitor C5 is discharged.

Next, in the stage 4 shown in FIG. 13D, the switching element Q1 is turned off and the switching element Q
2 is turned on, and to release the energy stored in the load circuit A up to that point, as shown in the figure, an AC power supply Vs, a diode D5, a capacitor C1, a diode D2 (a reverse conducting element of the switching element Q2). ), Load circuit A, path of AC power supply Vs, or capacitor C
5, diode D5, capacitor C1, diode D2
A current flows through the path of the (reverse energizing element of the switching element Q2), the load circuit A, and the capacitor C5. At the same time
The capacitor C5 is discharged.

Next, in the stage 5 shown in FIG. 13E, when all the energy of the load circuit A is released, the capacitor C3 is used as a power source, and as shown in FIG. A current flows through the path of the element Q2 and the capacitor C3, and the voltage of the capacitor C3 gradually decreases. At the same time, the capacitor C5 is charged from the AC power supply Vs via the filter circuit Z. When the switching element Q1 is turned on again and the switching element Q2 is turned off again, the state shifts to the state shown in the stage 1 in order to release the energy stored in the load until then.

FIG. 12 and FIG. 1 show the polarity of the input AC power supply Vs.
When the direction is opposite to the direction shown in FIG. 3, the circuit operates with almost the same operation. Explaining only the difference in the operation, when the polarity of the AC power supply Vs is in the direction shown in FIG. 12 and FIG.
When power is supplied from the AC power supply Vs directly to the load via the diode D5 when the switching element Q1 is on, when the direction of the AC power supply Vs is opposite to the direction shown in FIGS. When Q2 is on, AC power supply Vs, load circuit A, switching element Q
Second, power is directly supplied to the load through the path of the diode D6 and the AC power supply Vs. Note that capacitors C3 and C3
It is desirable that the capacitor 5 has a small capacity such that charge and discharge can be performed in one switching cycle.

In this embodiment, since the series circuit of the diode D1 and the capacitor C5 is provided on the input side of the power supply device X, the filter circuit Z is switched from the AC power supply Vs in the two stages for drawing the input current. The input current drawn through is supplied to the power supply device X together with the electric charge stored in the capacitor C5. The capacitor C5
, A charging current is supplied from the AC power supply Vs in the remaining three stages. Therefore, even when the instantaneous voltage of the AC power supply Vs is small, the input current increases, and even if the operation frequency increases when the input voltage specific to the self-excited circuit is small, the input distortion does not deteriorate. At the same time, since the self-excited oscillation frequency can be adjusted by the capacitance of the capacitor C5, the degree of freedom in design increases. Thus, the power supply X
The arrangement of the series circuit of the diode D1 and the capacitor C5 and the impedance Z on the input side increases the degree of freedom of design in the self-excitation control method, and increases the input current when the instantaneous voltage of the AC power supply Vs is small. In addition, the input distortion is improved.

In FIG. 11, the self-excited drive transformer T2
However, as shown in FIG.
2 and the leakage transformer T1, the same operation is performed, and the same effect can be obtained.

[0048]

According to the present invention, a switching element switched at a high frequency, a smoothing capacitor charged with a DC voltage, and a high frequency converter for converting the DC voltage of the smoothing capacitor into a high frequency power using the switching element. Means, and feedback means for feeding back a part of the high-frequency power to a power supply side, so that a current from an input side flows to the switching element during a partial period in one cycle of a switching operation of the switching element. A power supply circuit, an AC power supply connected to an input side of the power supply circuit, a rectifier circuit connected between the AC power supply and the power supply circuit to rectify the AC power supply, and a load circuit of the power supply circuit. A power supply device, wherein a series circuit of an impedance and a capacitor connected to the AC power supply; Rectifier element connected between the connection point of the power supply circuit and the power supply circuit. Therefore, even if the switching element is a self-excited control, the degree of freedom of design is expanded, and the instantaneous voltage of the AC power supply is increased. Is small, the input current increases, and the input distortion is improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first basic configuration of the present invention.

FIG. 2 is a circuit diagram showing a second basic configuration of the present invention.

FIG. 3 is a circuit diagram of a first embodiment of the present invention.

FIG. 4 is a circuit diagram for explaining a first operation of the first embodiment of the present invention.

FIG. 5 is a circuit diagram for explaining a second operation of the first embodiment of the present invention.

FIG. 6 is a circuit diagram of a modification of the first embodiment of the present invention.

FIG. 7 is a circuit diagram according to a second embodiment of the present invention.

FIG. 8 is a circuit diagram for explaining a first operation of the second embodiment of the present invention.

FIG. 9 is a circuit diagram for explaining a second operation according to the second embodiment of the present invention.

FIG. 10 is a circuit diagram of a modification of the second embodiment of the present invention.

FIG. 11 is a circuit diagram of a third embodiment of the present invention.

FIG. 12 is a circuit diagram for explaining a first operation of the third embodiment of the present invention.

FIG. 13 is a circuit diagram for explaining a second operation of the third embodiment of the present invention.

FIG. 14 is a circuit diagram of a modification of the third embodiment of the present invention.

FIG. 15 is a circuit diagram of a conventional example.

FIG. 16 is a circuit diagram for explaining a first operation of the conventional example.

FIG. 17 is a circuit diagram for explaining a second operation of the conventional example.

FIG. 18 is a waveform diagram showing a relationship between an input voltage and an input current in a conventional example.

[Explanation of symbols]

 Vs AC power supply Z Filter circuit DB Full-wave rectifier LA Discharge lamp C1 Smoothing capacitor C2 Coupling capacitor C3 Input distortion improvement capacitor C4 Resonance capacitor C5 Capacitor T1 Leakage transformer Q1 Switching element Q2 Switching element D3 Diode

Claims (11)

[Claims] A switching element that switches at a high frequency; a smoothing capacitor that is charged with a DC voltage;
A high-frequency converter for converting a DC voltage of the smoothing capacitor into high-frequency power using the switching element; and a feedback unit for feeding back a part of the high-frequency power to a power supply side, and one cycle of a switching operation of the switching element. A power supply circuit configured to allow a current from an input side to flow to a switching element during a partial period of time, an AC power supply connected to an input side of the power supply circuit, and a power supply circuit connected between the AC power supply and the power supply circuit. A rectifier circuit for rectifying the AC power supply, and a load circuit of the power supply circuit, a series circuit of an impedance and a capacitor connected to the AC power supply, a connection point of the impedance and the capacitor, and the power supply. A power supply comprising a rectifying element connected between the power supply circuit and a circuit, wherein the switching element is of a self-excited type; Location. 2. The power supply device according to claim 1, wherein the capacitance of the capacitor forming the series circuit with the impedance is set to about 1 μF or less. 3. The power supply device according to claim 1, wherein said impedance is an inductance. 4. The power supply device according to claim 1, wherein the impedance is a resistance. 5. The power supply device according to claim 1, wherein the impedance is a resonance circuit of an inductance and a capacitor. 6. A rectifier element connected between the connection point of the impedance and the capacitor and the power supply circuit, the rectifier circuit being connected between the AC power supply and the power supply circuit and rectifying the AC power supply. The power supply device according to claim 1, wherein the power supply device is also used. 7. A rectifier element connected between the connection point of the impedance and the capacitor and the power supply circuit, the rectifier circuit being connected between the AC power supply and the power supply circuit and rectifying the AC power supply. The power supply device according to claim 1, wherein the power supply device is a diode connected between the power supply circuits. 8. The power supply device according to claim 1, wherein the impedance or the capacitor connected to the AC power supply is also used as an input filter for removing a high frequency. 9. A power supply circuit comprising: a smoothing capacitor connected between a DC output terminal of the rectifier circuit via a diode; and a first capacitor connected in series between both ends of the smoothing capacitor and alternately turned on and off. And a second switching element; a load circuit including a resonance circuit and a load connected between a connection point of the first and second switching elements and one end of a DC output terminal of the rectifier circuit; The power supply device according to claim 1, further comprising an impedance element inserted between the DC output terminal and the smoothing capacitor. 10. A power supply circuit comprising: a first capacitor for smoothing having one end connected to one end of an output terminal of the rectifier circuit; and a high frequency alternately connected in series between both ends of the first capacitor. First and second switching elements that are turned on and off, first and second diodes connected in antiparallel to the first and second switching devices, respectively,
A primary winding is connected between a connection point of the second switching element and the other end of the output terminal of the rectifier circuit, and the AC power supply supplies either the primary winding or the first or second diode; And one end connected to a connection point between a primary winding of the transformer and an output terminal of the rectifier circuit, the transformer being connected to form a path through which a current flows through a first capacitor; The other end is connected to one of the terminals of the capacitor, and the primary circuit of the transformer and a second capacitor that performs a resonance action in accordance with ON / OFF of a switching element. The power supply device according to claim 1, wherein the power supply device is connected to a secondary winding. 11. A rectifier circuit connected between the AC power supply and the power supply circuit and rectifying the AC power supply includes a series circuit of first and second diodes and a series circuit of third and fourth diodes. The load circuit is constituted by one series circuit of a diode bridge formed by connecting each diode in the same forward direction and connected in parallel, and the load circuit is connected in series with the AC power supply, and has a connection point of the first and second diodes. The power supply circuit is connected between a connection point of a third and a fourth diode, and the power supply circuit is connected in anti-parallel with each of the diodes constituting the other series circuit of the diode bridge, and is alternately turned on and off. First and second switching elements;
A smoothing first capacitor connected in parallel between the DC output terminals of the diode bridge, at least one end of the DC output terminal of the diode bridge, and a connection point between the AC power supply and the load circuit; The power supply device according to claim 1, further comprising a second capacitor.