JPH10243656A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a leakage transformer which can input an input current corresponding to an output power and realize reduction in size of the leakage transformer in the case where an input current input from an AC power supply is limited by a resonance current of a load in an inverter having a resonance circuit including a leakage transformer. SOLUTION: In a power converting circuit to convert an DC voltage obtained by rectifying and smoothing an AC power source to a high frequency voltage, supplying a high frequency AC power to a load circuit via a leakage transformer and limiting an input current with a resonance current of load, a leakage transformed is formed in the structure that a part of the second coil L2 is wound overlapping on the first coil L1 and magnetic flux is canceled depending on the number of windings to control a leakage magnetic flux.

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 obtained by rectifying and smoothing an AC power into a high frequency and supplying the high frequency to a load circuit.

[0002]

2. Description of the Related Art FIG. 6 shows a basic circuit diagram of a conventional example. Hereinafter, the circuit configuration will be described. The transformer L ₃ and the capacitors C ₅ and C ₅ are connected to the AC input terminal of the full-wave rectifier DB.
_The AC power supply Vs is connected via a filter circuit composed of _six . The DC output terminals of the full-wave rectifier DB, a smoothing capacitor C ₁ through the diode D ₁ is connected. A series circuit of switching elements Q ₁ and Q ₂ composed of MOSFETs is connected in parallel to the smoothing capacitor C ₁ . A connecting point of the diodes D ₁ and the full-wave rectifier DB, between the connection point of the switching elements Q _1, Q _2, series circuit connection consisting of the primary winding L ₁ and the capacitor C ₃ Metropolitan leakage transformer Tl Have been. The secondary winding ends of L ₂ of the leakage transformer Tl, the power supply-side terminals of the filament of the discharge lamp la is connected, the capacitor C ₂ is connected in parallel between the non-power supply side terminal of the filament of the discharge lamp la ing. Further, the capacitor C ₄ is connected in parallel across diode D _1.

The operation of the above circuit will be described below.
First, the operation of the inverter will be described. The inverter consists of switching elements Q ₁ and Q ₂ and leakage transformer T
l (leakage inductor L ₀ ), capacitors C ₂ and C
₃ and a discharge lamp la. The switching elements Q ₁ and Q ₂ are alternately turned on and off at a high speed to convert the DC voltage of the smoothing capacitor C ₁ into a high-frequency alternating current, thereby lighting the discharge lamp la at a high frequency. The capacitor C ₂ is a discharge lamp la
Of constitute a preheating current conduction path of the filament, also it serves also as the resonant capacitor of the leakage inductor L _0. Capacitor C ₃ is a coupling capacitor for DC component cut.

[0004] When the switching element Q ₂ is turned on in the circuit, the capacitor C ₄ from the smoothing capacitor C _1,
Primary winding L ₁ of leakage transformer Tl, capacitor C
_3, a current flows through a path back to the smoothing capacitor C ₁ through the switching element Q _2. At this time, the capacitor C ₄ is the charge, | Vin |> when V _C1 -V _C4 is established, from the full-wave rectifier DB, 1 winding L ₁ of leakage transformer Tl, the capacitor C _3, the switching element Q ₂ The current will flow on the path returning to the full-wave rectifier DB via the rectifier DB. In other words, the capacitor C ₄ inserted between the output terminal and the smoothing capacitor C ₁ of the full-wave rectifier DB, the output voltage of the full-wave rectifier DB | shares the voltage of the difference between a smoothing capacitor C ₁ of the voltage V _C1 | Vin will be the output voltage of the full-wave rectifier DB | Vin | be lower than the voltage V _C1 of the smoothing capacitor C _1, the input current Iin flows high frequency. This input distortion improvement operation increases the input power factor. The capacitor C
Input current waveform removing the high frequency component by a filter circuit including a _5, C ₆ and the transformer L ₃ may be a waveform close to a small sine wave of harmonic components.

In this circuit, the input distortion is reduced by the operation for improving the input distortion.
The ratio of input current
Primary winding L of the transformer Tl₁Resonance current I flowing through_L1of
It is about 1/3. Therefore, the leakage transformer Tl rises.
The primary winding L₁Resonance current I flowing through_L1
Becomes smaller, the input current Iin drawn becomes
Add the smoothing capacitor C₁Voltage V_C1And the power supply
When the pressure falls below the peak value of Vin, the capacitor input
Input current distortion, so that input current distortion worsens
Will be invited. On the other hand, the rise of the leakage transformer Tl
The primary winding L₁Resonance current I flowing through_L1
Increases, the resonance current I_L1Included in the path
Switching element Q₁, Q_TwoSwitching loss at
Loss in the winding of the leakage transformer Tl
As a result, the circuit efficiency is reduced. In addition,
Primary winding L of the transformer Tl₁Resonance current I flowing through
_L1Is the current I flowing on the secondary side of the leakage transformer Tl.
_L2Is approximately twice the boost ratio. Therefore, the input that is pulled
In circuits where the current is limited to the resonant current of the load
Therefore, when designing the leakage transformer Tl,
Adjust the boost ratio of the leakage transformer Tl according to the flow,
Capacitor input-like current flows into input current Iin
Must not be. And to the flowing current
The appropriate wire diameter and the number of turns so that the magnetic flux does not saturate are determined.
You. FIG. 8 shows a leakage transformer using a conventional EE type core.
This shows the shape of the wire. In the figure, 1 is E core, 2 is bobbin, L₁
Is the primary winding, L _TwoIs a secondary winding.

FIG. 7 shows a circuit diagram of another conventional example. Less than,
The circuit configuration will be described. The AC input terminal of the full-wave rectifier DB, the AC power source Vs through a filter circuit composed of transformer L ₃ and capacitor C _5, C ₆ are connected. A capacitor C ₄ is connected to a DC output terminal of the full-wave rectifier DB, and a series circuit of a diode D ₁ and a smoothing capacitor C ₁ is connected in parallel with the capacitor C ₄ . A series circuit of switching elements Q ₁ and Q ₂ is connected in parallel to both ends of the smoothing capacitor C ₁ .
A connecting point of the diodes D ₁ and the full-wave rectifier DB, between the connection point of the switching elements Q _1, Q _2, series circuit connection consisting of the primary winding L ₁ and the capacitor C ₃ Metropolitan leakage transformer Tl Have been. Discharge lamp la ₁ and discharge lamp la ₂ are provided at both ends of the secondary winding L ₂ of the leakage transformer Tl.
Power supply side terminals of the filament are connected in series,
Discharge lamp la _1, is between the non-power supply side terminal of the filament lamp la ₂ are connected in parallel to the capacitor C ₂₁ and the capacitor C ₂₂ are each.

Hereinafter, the operation of the above circuit will be described. First, the operation of the inverter will be described. The inverter is composed of switching elements Q ₁ and Q ₂ and leakage transformer Tl
(Leakage inductor L ₀ ), capacitor C ₂₁ ,
C ₂₂ , condenser C ₃ , discharge lamp la ₁ and discharge lamp la ₂
It is composed of The switching elements Q ₁ and Q ₂ are alternately turned on and off at a high speed to convert the DC voltage of the smoothing capacitor C ₁ into a high-frequency alternating current, thereby lighting the discharge lamps la ₁ and la ₂ at high frequency. Capacitors C ₂₁ and C ₂₂ are connected to discharge lamp la
_1, constitute a preheating current conduction path of la ₂ filaments and also doubles as the resonant capacitor of the leakage inductor L _0. Capacitor C ₃ is a coupling capacitor for DC component cut.

In the above circuit, there are the following six operation modes. Mode: When the switching element Q ₁ is turned on, the switching element Q ₁ from the capacitor C _1, the capacitor C _3,
Primary winding L ₁ of leakage transformer Tl, capacitor C
Capacitor C in the path back to the smoothing capacitor C ₁ via the ₄
Current flows until ₄ is charged to Vdc.

[0009] Mode: from the state of the mode,
Sa C_FourIs charged to Vdc, the resonance current
Primary winding L of the transformer Tl₁, Diode D₁,
Switching element Q₁, Capacitor C_ThreeLeek through
Primary winding L of the transformer Tl ₁Flows along the path.

Mode: From the mode state, the switching element Q ₁ is turned off and the switching element Q ₂ is turned on, so that the resonance current causes the primary winding L ₁ of the leakage transformer Tl, the diode D ₁ , a smoothing capacitor C _1, the internal diode of the switching element Q _2, through a path of the primary winding L ₁ of leakage transformer Tl through a capacitor C _3.

[0011] Mode: The resonance current commutation causes
Sensor C_Three, Switching element Q_Two, Capacitor C_Four,
Primary winding L of cage transformer Tl₁Through conden
Sa C _ThreeThe resonance current flows through the path of_FourDischarge of
Is performed.

Mode: | Vin from the mode state
|> From the time that the V _C1, the resonant current via the power Vs, the full-wave rectifier DB, 1 winding L ₁ of leakage transformer Tl, the capacitor C _3, through the switching element Q ₂ of the full-wave rectifier DB Flows on the route.

Mode: switch from the mode state
Element Q₁Turns on and the switching element Q_TwoIs off
With the switching operation, the resonance current becomes the power supply Vs
Through the full-wave rectifier DB and the leakage transformer Tl
Primary winding L₁, Capacitor C _Three, Switching element Q₁
Built-in diode, smoothing capacitor C₁Through the whole wave
It flows along the path of the sink DB.

In each of the above operation modes, the input current Iin flows at a high frequency in the modes. Therefore, the input power factor is increased by the input distortion improving operation. The input current waveform removing the high frequency component by a filter circuit including a capacitor C _5, C ₆ and the transformer L ₃ may be a waveform close to a small sine wave of harmonic components. Except for the above operation modes, it is the same as the conventional example of FIG.

[0015]

In the above-described circuit, when the size of the leakage transformer Tl is reduced in order to reduce the cost, there are the following problems. Considering first the flux, the maximum magnetic flux density Bm is the primary winding is proportional to the voltage V ₁ applied to L _1, the driving frequency F, the cross-sectional area of the core through the magnetic flux is S, and the primary winding L ₁ Is inversely proportional to the number of turns N ₁ . Also, in order not to saturate the magnetic flux,
Past examples have shown that the design must be such that the maximum magnetic flux density Bm is between 0.25 and 0.3. Therefore, as the core size becomes smaller, the cross-sectional area S of the core becomes smaller.
Is small, so that the maximum magnetic flux density Bm is satisfied by 1
Need to increase the number of turns N ₁ of the primary winding L ₁ is there.

However, the leakage flux φL and the number of turns N₁Is proportional
Because of the relationship, the number of turns N₁Increase and leakage in
Dacta L₀Will increase. Therefore, Rieke
When miniaturizing the storage transformer Tl, the leakage-in
Dacta L₀Increases in proportion to the square of the turns ratio.
As a result, there is a problem that a predetermined output cannot be obtained. An example
For example, if the number of turns is N₁₁To N₁₂Leakage if increased to
The inductor is L₀₁To L ₀₂, Then L
₀₂≒ (N₁₂/ N₁₁)^Two× L₀₁Becomes To increase the output
Means to lower the driving frequency F and strengthen the resonance
It is conceivable that when the drive frequency F is lowered, the maximum magnetic flux density
Bm becomes large. Also, increase the transformer boost ratio.
Although it is conceivable to increase the circuit effect,
The capacitor input
Reduce the boost ratio as much as possible to avoid
Cage inductor L₀It is desirable that the design be small. I
Therefore, conventional designs have room to reduce the core size.
The leakage inductor L₀Is bigger
The leakage transformer Tl can be downsized because it is too
There was a problem that there was not.

[0017]

According to the present invention, the above
In order to solve the problem, as shown in FIG. 6 or FIG.
The DC voltage obtained by rectifying and smoothing the AC power supply Vs is converted to a high frequency.
To the load circuit via the leakage transformer Tl.
Supply AC power of wave and input by resonance current of load
In power conversion circuits where current is limited, leakage
As shown in FIG. 1, the configuration of the lance_Twoof
Part of the first winding L₁It is characterized by being wound around
Things. Alternatively, as shown in FIG.
The core of the ditransformer Tl comprises first and second cores,
As shown in FIG. 3, the first winding L ₁Is wound on the first core
Turned, the second winding L_TwoOn the second core and the first winding
L ₁And that it is wound both on the same core
It is a sign.

[0018]

FIG. 1 shows a first embodiment of the present invention. In this embodiment, the leakage transformer T is used in a circuit in which the input current drawn by the resonance current of the load is limited as shown in FIG. 6 or 7, for example.
1 is configured as shown in FIG. 1 to obtain a leakage inductor L ₀ through which a predetermined output current flows.
An input current suitable for the output power can be drawn, and the leakage transformer Tl can be downsized. Leakage transformer Tl in this embodiment
Uses a so-called EE core (E core + E core) as shown in FIG. 2, and the bobbin shape is such that the primary winding and the secondary winding can be individually wound. The first and primary winding L ₁ is wound on one bobbin, and the secondary winding L ₂ is wound on the other bobbins, part of the secondary winding L ₂ is a magnetic flux It is wound to overlap with the primary winding L ₁ so as to cancel. The shapes of the core and the bobbin shown in FIG. 1 are merely examples, and may have different shapes.

Thus, the primary winding L ₁ and the secondary winding L ₂
, The magnetic flux is canceled out in accordance with the number of wrapped windings, and the leakage magnetic flux can be suppressed. That is, by the leakage transformer Tl to this configuration, changing the number of turns of winding overlapped, it is possible to adjust the leakage inductor L _0.

In this embodiment, a simple and inexpensive bobbin is used.
A portion of the secondary winding to cancel the magnetic flux by winding superposed with the primary winding, suppressing an increase in the leakage inductor L _0, with obtaining a predetermined leakage inductor L _0, the size of the leakage transformer Tl It is possible. In the circuit shown in FIG. 6, when the load is two lamps, a configuration in which two discharge lamps are connected in parallel to both ends of the secondary winding via a balancer can be easily considered. As described above, even when a plurality of discharge lamps are provided, the effect of the invention shown in the present embodiment is the same.

FIG. 3 shows a second embodiment of the present invention. The configuration of the leakage transformer in this embodiment is as follows.
A so-called EE core is used, and the shape of the bobbin 2 is such that the primary winding L ₁ and the secondary winding L ₂ can be individually wound. First and primary winding L ₁ is wound on one bobbin, and the secondary winding L ₂ is wound on the other bobbin, and the part is set around the primary winding Wound so as to overlap on the same core. Depending on the shape of the bobbin, there is also a winding method as shown in FIG.

According to this embodiment, it is easy to wind both the primary winding and the secondary winding, and by winding a part of the secondary winding on the same core as the primary winding, the number of windings can be reduced. depending stronger binding of primary and secondary side, but the leakage magnetic flux can be the adjustment of the leakage inductor L ₀ by reducing small, and which enables miniaturization of the leakage transformer. For example, in a circuit in which the input current drawn by the resonance current of the load is limited as shown in FIG. 6 or 7, the leakage transformer Tl is configured as shown in FIG. 3 or FIG. with obtaining the leakage inductor L ₀ passing the output current, it is possible to draw an input current corresponding to the output power, and one in which it becomes possible size reduction of the leakage transformer Tl.

FIG. 5 shows a third embodiment of the present invention. The configuration of the leakage transformer in this embodiment is as follows.
A so-called EE core is used, and the shape of the bobbin 2 is such that the primary winding L ₁ and the secondary winding L ₂ can be individually wound. First and primary winding L ₁ is wound on one bobbin, and the secondary winding L ₂ is wound on the other bobbin, a portion of which is wound around the primary winding L ₁ It is wound so as to overlap on the same core. Further, the secondary winding L
Some of ₂ are wound to overlap the primary winding L ₁ so as to cancel out the magnetic fluxes.

In this embodiment, in a circuit in which the input current drawn by the resonance current of the load is limited as shown in FIG. 6 or 7, for example, the leakage transformer Tl has a configuration as shown in FIG. by, with obtaining a leakage inductor L ₀ passing a predetermined output current, after it possible to draw an input current corresponding to the output power, and makes it possible to miniaturize the leakage transformer Tl.

As described in the prior art, for example, in the circuit shown in FIG. 6 or FIG. 7, the input current drawn by the resonance current of the load is limited, and the load circuit includes a resonance circuit including, for example, a fluorescent lamp. When a circuit is used, the resonance current of the load is limited to a lamp current or the like. These two factors also limit the step-up ratio of the transformer. The wire diameter of each winding is determined by the current flowing through the primary and secondary sides of the transformer. The number of turns of the primary winding and the secondary winding is determined in consideration of the core size and the saturation of the magnetic flux. The space where the primary winding and the secondary winding are wound is determined by the core size and the bobbin shape.

According to this embodiment, even under these restrictions, a part of the secondary winding is previously set to the same core as the primary winding in accordance with the turn ratio of the primary winding and the secondary winding. It is possible to adjust the leakage inductor to a predetermined leakage inductor by winding the secondary winding upward and partially winding the secondary winding on the primary winding, thereby efficiently reducing the size of the leakage transformer.

[0027]

According to the present invention, in a circuit in which the input current to be drawn is limited by the resonance current of the load, it is possible to obtain a leakage inductor through which a predetermined output current flows, and to draw in an input current corresponding to the output power. In addition to the configuration of a possible leakage transformer, there is an effect that the size of the leakage transformer can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is a front view showing a shape of a core used in the first embodiment of the present invention.

FIG. 3 is a front view showing a configuration of a main part of a second embodiment of the present invention.

FIG. 4 is a front view showing a main configuration of a modification of the second embodiment of the present invention.

FIG. 5 is a front view showing a configuration of a main part of a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing an example of a conventional power supply device.

FIG. 7 is a circuit diagram showing another example of a conventional power supply device.

FIG. 8 is a front view showing a main part configuration of a conventional power supply device.

[Explanation of symbols]

1 E core 2 bobbin L _{1 1} winding L _{2 2} winding

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01F 31/06 501Z (72) Inventor Naoki Onishi 1048 Odakadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd.

Claims (7)

[Claims] 1. A DC voltage obtained by rectifying and smoothing an AC power supply is converted into a high frequency, a high frequency AC power is supplied to a load circuit via a leakage transformer, and an input current is limited by a resonance current of the load. In a power conversion circuit, a part of a second winding of a leakage transformer is wound so as to overlap with a first winding. 2. A DC voltage obtained by rectifying and smoothing an AC power supply is converted into a high frequency, a high frequency AC power is supplied to a load circuit via a leakage transformer, and an input current is limited by a resonance current of the load. In the power conversion circuit, a core of the leakage transformer includes first and second cores,
The first winding is wound on the first core, and the second winding is wound both on the second core and on the same core as the first winding. Power supply device characterized. 3. A full-wave rectifier for full-wave rectifying an AC power supply, a smoothing capacitor connected in parallel to a DC output terminal of the full-wave rectifier via a diode, and a parallel connection across both ends of the diode. , The capacitor is connected in parallel at both ends of the smoothing capacitor and alternately turned on,
A series circuit of the first and second switching elements to be turned off, and diodes connected in anti-parallel to the first and second switching elements, respectively; a connection point between the DC output terminal of the full-wave rectifier and the diode; A series circuit of a first winding of a leakage transformer and a coupling capacitor for cutting DC is connected between a connection point of the first and second switching elements, and both ends of a second winding of the leakage transformer are connected to both ends of the second winding of the leakage transformer. 2. The power supply device according to claim 1, wherein in a circuit to which a load circuit is connected, the leakage transformer has a configuration in which a part of the second winding is overlapped with the first winding and wound. . 4. A full-wave rectifier for full-wave rectification of an AC power supply, a smoothing capacitor connected in parallel to a DC output terminal of the full-wave rectifier via a diode, and a parallel connection between both ends of the diode. , The capacitor is connected in parallel at both ends of the smoothing capacitor and alternately turned on,
A series circuit of the first and second switching elements to be turned off, and diodes connected in anti-parallel to the first and second switching elements, respectively; a connection point between the DC output terminal of the full-wave rectifier and the diode; A series circuit of a first winding of a leakage transformer and a coupling capacitor for cutting DC is connected between a connection point of the first and second switching elements, and both ends of a second winding of the leakage transformer are connected to both ends of the second winding of the leakage transformer. In a circuit in which a load circuit is connected, the core of the leakage transformer includes first and second cores,
Is wound on the first core, and the second winding is wound both on the second core and on the same core as the first winding. The power supply device according to claim 2. 5. The leakage transformer core comprises first and second cores, a first winding wound on the first core, a second winding on the second core, and The winding is wound on both the first winding and the same core, and a part of the second winding is wound on top of the first winding. Power supply. 6. The power supply device according to claim 3, wherein the load circuit includes a discharge lamp and a capacitor. 7. A power supply terminal of a filament of a fluorescent lamp is connected to both ends of the second winding, and a capacitor is connected in parallel between the non-power supply terminals of the filament of the fluorescent lamp. Item 7. The power supply device according to any one of Items 1 to 6.