JPH07283049A - Constant voltage transformer - Google Patents

Abstract

PURPOSE:To enhance the AC-AC conversion efficiency and the waveform under no-load significantly by applying at least a winding to be controlled, connected in series with the primary or secondary winding of power transformer section, and a control winding for varying the inductance of the winding to be controlled to a saturable reactor. CONSTITUTION:The primary winding N1 of a power transformer 2 is connected across an AC power supply 1 feeding an AC input voltage V1. The transformer 2 comprises primary, secondary and tertiary windings N1, N2, N3. The secondary winding N2 is connected with a load ZL, through a winding Ni to be controlled connected with one pole thereof. A saturable reactor 3 comprises the winding Ni to be controlled having impedance Li and a control winding NC arranged orthogonally. The winding Ni is connected in series with the secondary winding N2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant voltage transformer device capable of suppressing fluctuations in AC output voltage obtained on the secondary side, for example.

[0002]

2. Description of the Related Art As a transformer device, a constant voltage transformer device is known in which an AC output voltage obtained on the secondary side is constant with respect to a change in load or the like. Figure 10
Shows an example of the configuration of such a constant voltage transformer device. In this figure, 10a is an I type core and 10b is an E type core.
The mold core is shown, and both are combined to form an EI core. At this time, a gap shown by G in the figure is provided in the central magnetic leg, and the outer leg on the right side of the figure has a width smaller than that of the outer leg on the left side so as to have a small cross-sectional area to facilitate saturation. It is formed to be narrow. N ₁₁ wound around the outer leg (primary side iron core) on the left side of the drawing indicates a primary winding, and is supplied with an AC input voltage V ₁ . The current flowing through the primary winding N ₁₁ is indicated by I ₁ . Next, similarly, N ₁₃ wound around the primary iron core indicates a tertiary winding,
The tertiary winding N ₁₃ is connected in series to the secondary winding N ₁₂ described below, and one end thereof is connected to the output terminal of one pole of the AC output voltage V ₂ . Further, N ₁₂ wound around the outer leg (secondary iron core) on the right side of the drawing is a secondary winding capable of obtaining an AC output voltage V ₂ according to the winding ratio with the primary winding N ₁₁ . It will be a line. This secondary winding N ₁₂
The current flowing through is indicated by I ₂ . The secondary for winding N ₁₂ and the winding N ₂₂ is wound in order to reduce the capacitance of the parallel resonance capacitor C ₁₀ to be described below, the secondary winding N
One end of ₁₂ is connected to the tertiary winding N _13, and the secondary winding N ₁₂
AC output voltage V with respect to tap position with winding winding N ₂₂
The output terminal of the other pole of ₂ is connected. And C
₁₀ is a parallel resonance capacitor, and as shown in the figure, the secondary winding N
₁₂ to winding N ₂₂ are provided in parallel.

In the circuit of the constant voltage transformer device as described above, a parallel resonance circuit is formed by the inductance of the secondary windings N ₁₂ to N ₂₂ and the capacitor C ₁₀ , and the secondary side iron core is saturated. A so-called ferroresonant constant voltage transformer device is constructed which is made to resonate and keeps the AC output voltage V ₂ (effective value) obtained on the secondary side constant by utilizing the phase change of the current caused thereby. The tertiary winding N ₁₃ is
Since the output voltage V ₂ slightly increases due to the input voltage V ₁ near the rated input voltage, a tertiary voltage proportional to the input voltage is generated by the tertiary winding N ₁₃ in this way, and the secondary side parallel resonant circuit voltage is generated. It is a compensation winding that obtains the difference between

Here, FIG. 11A is a circuit diagram equivalently showing the constant voltage transformer device having the above-mentioned configuration, and the primary side circuit is shown as being replaced with a secondary side circuit. In this figure, the secondary conversion primary voltage V ₁₁ which is the input voltage is represented by V ₁₁ = n · V ₁ (n = N ₁₂ / N ₁₁ : voltage conversion ratio) as shown in the figure. Further, Lg represents a leakage inductance, and an inflow current I ₁₁ flowing in the circuit via the leakage inductance Lg is represented by I ₁₁ = I ₁ / n as shown in the figure. Then, the inductance L parallel resonance circuit by _S and the capacitance capacitance C is formed, shows the current through the inductance L _S in I _S, and to indicate the current flowing through the capacitance C in the I _C. V ₂ represents a secondary voltage as an AC output voltage.

Next, FIG. 11 (b) shows operating characteristics in the case of no load obtained from the equivalent circuit of FIG. 11 (a). The curve a is saturated as the relationship (ωL _S ) between the current I _S flowing in the secondary winding (inductance L _S ) and the voltage V ₂ when the primary side is opened and the voltage V ₂ is applied to the secondary side. The characteristic is shown by the straight line b, which shows the relationship between the current I _C and V ₂ flowing when the voltage V ₂ is applied to the capacitance C, and the curve c is the current (I _S + I _C ) which is the combination of the curve a and the straight line b. The relationship of the voltage V ₂ is shown, the straight line d shows the voltage drop (ωLg · I ₁₁ ) caused in the leakage inductance Lg by the current I ₁₁ , and the curve e is the voltage V ₁₁ obtained based on the straight line d and the curve c. And the current I ₁₁ are shown. Therefore, assuming that the primary voltage is V _11a as shown in the figure, the inflow current I _11a is obtained from the curve e, and the secondary voltage V _2a is obtained from the curve c. Further, the current flowing through the inductance L _S at this time is I _Sa from the curve a,
The current flowing through the capacitance C becomes I _Ca from the straight line d, and the fluctuation of the secondary voltage V ₂ can be reduced even when the primary voltage V ₁ changes.

[0006]

However, as the AC input voltage as described above, for example, the output capacitance 100
VA, input voltage fluctuation range 100V ± 20V, load fluctuation range: full load-no load, output voltage fluctuation range 100V ± 2
Considering the specification of V, A at AC100V
It is known that the C-AC conversion efficiency is about 79%. That is, 21% is considered to be loss due to copper loss, iron loss, etc. of the constant voltage transformer device, and considerable heat is generated.
In addition, the parallel resonance capacitor C ₁₀ is C =
A standard of about 10 μF / withstand voltage of about 1000 V is used, but it is necessary to have such a high withstand voltage as described above, so that the component itself becomes large. Further, as the structure of the transformer, the degree of coupling between the primary winding N ₁₁ and the secondary winding N ₁₂ is set to about 0.5 to 0.7, so that the leakage magnetic flux is large and, in reality, the winding or the core is Must be magnetically shielded. Further, as described above, in order to reduce the capacitance of the parallel resonant capacitor C ₁₀ , it is necessary to further wind the winding N ₂₂ with respect to the secondary winding N ₁₂ , but in reality, the windings N _{12 to} N ₁₂ The total number of turns of ₂₂ is required to be about three times that of the secondary winding N ₁₂ , and for example, the number of turns of the secondary winding N ₁₂ is 39.
If the number of turns is set to about 0, the total number of turns of the windings N _{12 to} N ₂₂ needs to be increased to about 1035. For this reason, a considerable insulation distance must be provided in order to ensure the insulation between the windings wound around the transformer, which increases the window area for the windings, resulting in an increase in the size of the transformer itself. Will be done. Further, in the constant voltage transformer device having the above-mentioned configuration, there is a problem that the waveform distortion increases particularly when there is no load, and for example, the third harmonic component is superposed to generate a voltage waveform distortion of about 10%. .

[0007]

In order to solve the above-mentioned problems, the present invention excites an AC voltage by a primary winding to which an AC input voltage is supplied and an AC input voltage supplied to the primary winding. And a power transformer having a secondary winding provided for the secondary side, and a level of a DC voltage obtained based on the AC voltage excited in the tertiary winding can be detected. The constant voltage transformer device is configured to include a DC voltage detection circuit and a saturable reactor including a control winding through which a detection signal of the DC voltage detection circuit flows as a control current. The saturable reactor has at least a controlled winding connected in series to the primary winding or the secondary winding of the power transformer and a control winding for varying the inductance of the controlled winding. I decided to wear it and configure it. Alternatively, a control winding is provided for the power transformer so that the main magnetic flux of the control winding can be varied so that the power transformer is configured as a saturable reactor. Further, in the above-mentioned configuration, the power choke coil connected in series with the primary winding is provided. In addition, a double E-type core formed by having a pair of inner magnetic legs and outer magnetic legs on both outer sides of the central magnetic leg is used for the power transformer, saturable reactor, power choke coil, and the like described above. I decided. And the above power transformer,
All or a part of the saturable reactor and the power choke coil are provided for one transformer to constitute a so-called composite type transformer.

[0008]

According to the above construction, the control current flowing through the control winding is varied based on the result of detecting the fluctuation of the DC voltage obtained on the secondary side of the power transformer, and the controlled winding connected to the primary side is changed. By controlling the inductance of the wire, or by controlling the main magnetic flux of the power transformer,
It is possible to obtain a constant voltage transformer device that performs constant voltage control of the secondary side DC voltage. In addition, if a power choke coil connected in series with the primary winding is provided in this configuration, the power factor is improved for the secondary side rectifier circuit. If a double E-type core is used for the saturable reactor, the power transformer, and the power choke coil, it is possible to obtain a transformer with low leakage magnetic flux, and these can be combined into a single transformer. For example, only one transformer part is required in the circuit of the constant voltage transformer device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the constant voltage transformer device of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing a constant voltage transformer device of the present embodiment. In FIG. 1, reference numeral 1 denotes an AC power source for supplying an AC input voltage V ₁ , both poles of which are primary windings N of a power transformer 2.
Connected with ₁ . Reference numeral 2 denotes a transformer, in which a primary winding N ₁ is wound on the primary side, and a secondary winding N ₂ and a tertiary winding N ₃ as output windings are wound on the secondary side. Note that ()
L ₁ and L ₂ shown therein indicate the inductances of the primary winding N ₁ and the secondary winding N ₂ , respectively. Then, in the power transformer 2, the secondary winding N ₂ is connected to the load Z _{L at} one pole through the controlled winding Ni. Also,
Both ends of the tertiary winding N ₃ have rectifying diodes D ₁ and D respectively.
Connected to the anode side of ₂ . Also, the tertiary winding N
The tap output of ₃ is grounded. Reference numeral 3 denotes a saturable reactor including a controlled winding Ni having an inductance Li and a control winding N _C, which is, for example, an orthogonal type in which the windings are orthogonal to each other as shown in the figure. It In this saturable reactor, the controlled winding Ni is connected in series to the secondary winding N ₂ as shown in the figure. Z _L in the secondary side circuit indicates the load, and V ₂ indicates the output voltage of the secondary side circuit.

Further, D ₁ and D ₂ are rectifying diodes, respectively, and C ₁ provided between the connection point of the cathodes of the rectifying diodes D ₁ and D ₂ and the ground is a smoothing capacitor. Are formed.
In this case, an AC voltage corresponding to the turn ratio with the primary winding N ₁ is excited in the tertiary winding N ₃ , but this AC voltage is full-wave rectified by the rectifying diodes D ₁ and D ₂ and further smoothed. The DC voltage E is obtained by being smoothed by the capacitor C ₁ .

Next, Q ₁ represents a transistor for detecting an error in the DC voltage E. The base of this transistor is
It is connected to the connection point of the resistors R ₁ and R _{2 in} series with the DC voltage E and ground, the emitter is connected to the DC voltage E via the resistor R ₃ , and the collector is connected to ground via the resistor R _4. Connected. D ₃ is a Zener diode provided to obtain a predetermined reference voltage, and is provided such that the cathode is connected to the emitter side of the transistor Q ₁ and the anode is connected to the ground side as shown in the figure. Q
₂ is a transistor for supplying a control current to the control winding N _C, the base of the transistor Q ₂ is connected to the collector of the transistor Q ₁ via the resistor R ₅ as in FIG. The collector is connected to one end of the control winding N _C , and the emitter is grounded. The other end of the control winding N _C is connected to the DC voltage E.

The constant voltage transformer device having the above structure operates as follows. Here, when the AC input voltage V ₁ rises due to the influence of the AC power supply 1 or the load Z _L , the AC output voltage V ₁ excited by the secondary winding N ₂ and applied to the load Z _{L 2} rises accordingly. Then, similarly, the DC voltage E also rises. As a result, the potential between the base and the ground obtained by dividing the DC voltage E by the resistors R ₁ and R ₂ rises. At this time, the potential between the emitter of the transistor Q _{1 and} the ground is kept constant by the Zener diode D ₃ . For this reason,
Since the base current flowing from the emitter of the transistor Q ₁ to the base decreases according to the change of the base potential, the base current flowing from the collector to the base of the transistor Q ₂ via the resistor R ₅ also decreases. Thus also decreases the collector current of the transistor Q ₂ but, since the the collector current or a control current I _C flowing through the control winding N _C, the control current I _C flowing through the control winding N _C in this case is It will decrease as the DC voltage E increases. Then, in response to this, the DC superposition component with respect to the controlled winding Ni decreases and its inductance Li increases.

Here, the primary winding N₁ , N₂ The number of turns of it
Each N_1T, N_2TAs a voltage conversion from the primary side to the secondary side
Rate N_2T/ N_1TLet n be the AC output voltage of the secondary side circuit
V₂Is V₂ = NV₁ ・ {L₂ / (L₂ + Li)} = 1 / (1 + Li / L₂ ) N ・ V ₁ It is represented by (Equation 1). Therefore, as in the above case,
If the stance Li increases, the AC output voltage
V₂ Will be reduced.

On the other hand, when the AC input voltage V ₁ changes such that it decreases, the AC output voltage V ₂ decreases accordingly. Further, the DC voltage E also decreases accordingly. As a result, the potential between the base and ground obtained by dividing the DC voltage E by the resistors R ₁ and R ₂ is lowered, and in this case, the base current flowing from the emitter of the transistor Q ₁ to the base is increased. As a result, the base current flowing from the collector to the base of the transistor Q ₂ via the resistor R ₅ also increases, and the collector current also increases accordingly. Therefore, in this case, the control current I _C flowing through the control winding N _C increases in accordance with the drop of the DC voltage E, and the inductance Li of the controlled winding Ni decreases. Then, when the inductance Li becomes small in this way, the AC output voltage V ₂ rises accordingly from (Equation 1).

Here, FIG. 2 shows a current I flowing in the secondary side circuit.
₂ shows the relationship between ₂ and the inductance Li of the controlled winding Ni, and the parameter is the control current I _C. For example, let the inductance of the primary winding and the secondary winding be L ₁ = L ₂
= 500 mH, the inductances of both are constant, so based on this figure, the inductance L
If the components of the circuit shown in FIG. 1 are selected so that i can be varied in the range of about 50 mH to 500 mH, (Equation 1)
Thus, it is possible to control the AC output voltage V ₂ to be constant within the range of V ₂ = (0.91 to 0.09) n · V ₁ (Equation 2).

Now, an example of the structure of the power transformer 2 in this embodiment will be described with reference to FIGS. 3 (a) and 3 (b). For example, in the power transformer 2 shown in FIG. 3 (a), the half-shaped cores 2a and 2b are formed as an eye-shaped core in which magnetic legs are combined so as to face each other.
The two inner magnetic legs are provided with gaps G and G, respectively. The primary winding N ₁ is wound around the two inner magnetic legs on the half-shaped core 2a side as shown in the figure, and the primary winding N ₁ is wound on the two inner magnetic legs on the half-shaped core 2b side. The secondary winding N ₂ and the tertiary winding N ₃ are wound as shown. Although the secondary winding N ₂ actually has two terminals and the tertiary winding N ₃ has three terminals, these terminals are collectively shown as two terminals here. For example, in the case where the power transformer 2 is configured in this way, the main magnetic flux is formed by using two inner magnetic legs as magnetic paths, and the leakage magnetic flux at this time is the two outer magnetic fluxes on both outer sides of the two inner magnetic magnetic flux legs. A transformer with low leakage magnetic flux can be obtained by being absorbed by the magnetic legs.

Further, the power transformer 2 shown in FIG.
In Fig. 1, the double E-shaped cores 2a and 2b formed in a shape in which two E-shaped cores are connected are combined so that their magnetic legs face each other as shown in the figure. A gap G is provided at a portion where the central magnetic legs of each of the two oppose each other. The primary winding N ₁ is wound around the central magnetic leg on the double E-shaped core 2a side as shown in the figure, and the secondary winding N ₂ is wound around the central magnetic leg on the double E-shaped core 2b side.
And the tertiary winding N ₃ is wound as shown. In the case where the power transformer 2 is configured as described above, the main magnetic flux forms a magnetic path from the central magnetic leg to the two inner magnetic legs on both outer sides of the central magnetic leg. Since it is absorbed by the two outer magnetic legs on both outer sides, a transformer with low leakage magnetic flux can be obtained as in the power transformer 2 of FIG. 3A. In this case, for example, as shown in FIG. The leakage flux is about 1/30 to 1/50 as compared with the transformer having the structure. The cores of the transformer shown in FIGS. 3A and 3B may be, for example, laminated silicon steel plates. In such a configuration, in addition to the low leakage magnetic flux as described above, for example, in the power transformer 2 as shown in FIG. 3B, the coupling coefficient k of the primary and secondary windings is, for example, k = As a result of about 0.95, AC
-AC power conversion efficiency is also improved to about 94%.

Next, a specific example of the structure of the saturable reactor 3 in this embodiment will be described with reference to FIG. For example, the saturable reactor 3 shown in FIG.
As shown, the E-shaped core 3a and the double E-shaped core 3b are combined so as to be orthogonal to each other, and the controlled winding Ni is wound around one central magnetic leg of the double E-shaped core 3a. On the other hand, a control winding N _C is wound around the central magnetic leg of the double E-shaped core 3b. Alternatively, FIG. 4 (b)
, The double E-shaped core 3a and the E-shaped core 3b are combined so as to be orthogonal to each other, and the controlled winding Ni is wound around one central magnetic leg of the double E-shaped core 3a.
The control winding N _C may be wound around the central magnetic leg of the shaped core 3b. For example, in the saturable reactor 3, the leakage inductance of the controlled winding Ni through which the AC input current on the primary side particularly flows becomes a problem, but if the saturable reactor 3 is configured as described above, the leakage magnetic flux should be significantly reduced. Is possible.

Further, it is conceivable to integrate the power transformer 2 and the saturable reactor of this embodiment as a composite type transformer as shown in FIG. For example, in the composite type transformer 4 shown in FIG. 5, the double E-shaped core 4a is combined with the double E-shaped core 4b so as to be orthogonal to each other as shown in the figure, and the double E-shaped core 4b is further combined with the double E-shaped core 4b. A core is obtained by combining the cores 4c so as to be orthogonal to each other. Then, the primary winding N ₁ , secondary windings N ₂ and N ₃ are wound around the central magnetic leg of the double E-shaped core 4a,
It is configured by winding the controlled winding Ni around the central magnetic flux of the double E-shaped core 4b and winding the control winding N _C around the central magnetic flux of the double E-shaped core 4c. According to this structure, the transformer portion of the constant voltage transformer device of this embodiment can be integrated into one, and in this case also, a transformer with low leakage magnetic flux can be obtained, and the coupling between the primary side and the secondary side can be obtained. The degree will also be improved. The cores of the transformer shown in FIGS. 3, 4, and 5 described above may be, for example, laminated silicon steel plates.

FIG. 6 shows a constant voltage transformer device as another embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the case of this embodiment, the controlled winding Ni is provided in the primary side circuit, that is, it is provided in series with the primary side winding N _{1 of the} power transformer 2. In this case, the secondary side output voltage V ₂ is expressed by V ₂ = {1 / (1 + Li / L ₁ )} · n · V ₁ (equation 2). Further, the transistors Q ₁ and Q _{2 of} this embodiment are
Similarly to the previous embodiment, the voltage detection circuit section including the peripheral parts and the peripheral parts also have a function of Li when the primary side input voltage V ₁ rises.
Becomes larger and the primary side input voltage V ₁ drops, the control current I _C flowing through the control winding N _C changes so that Li becomes smaller. Therefore, the voltage detection circuit corresponds to (Equation 2). By selecting each part such as a section, a constant voltage can be achieved.

Further, the power transformer 2 in the present embodiment.
The specific configuration example of the saturable reactor 3 may be, for example, the same configuration as that shown in FIGS. 3 and 4 in the previous embodiment, but as shown in FIG.
It is also possible to configure the power transformer 2 and the saturable reactor 3 as a single type transformer as a composite type transformer. In the composite transformer 4 shown in FIG. 7, the double E-shaped core 4a is replaced by the double E-shaped core 4b.
Are combined so as to be orthogonal to each other as shown in the figure, and further, a double E-shaped core 4b and a double E-shaped core 4c are combined to be orthogonal to each other. In this core, a primary winding N ₁ , secondary windings N ₂ and N ₃ are wound around the central magnetic leg of the double E-shaped core 4a. The central magnetic flux of the double E-shaped core 4b is wound with the controlled winding Ni connected to the primary winding N ₁ as shown in the figure, and the central magnetic flux of the double E-shaped core 4c is controlled. The winding N _C is wound and configured. With this configuration,
Similar to the composite transformer 4 in the previous embodiment, it is possible to combine the transformer parts in the circuit of the constant voltage transformer device into one, and also in this case, a transformer with low leakage magnetic flux can be obtained.

FIG. 8 shows still another embodiment of the constant voltage transformer device of the present invention. The same parts as those in FIGS. 1 and 6 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the winding Ni serves as a power choke coil PCC and is connected in series to the primary winding N ₁ . In this case, the inductance Li of the winding Ni is equal to the AC input voltage V
It is set to improve the power factor according to the conditions such as the level of ₁ . The control winding N _C is provided for the power transformer 2 as shown in the figure. That is, in the case of this embodiment, the power transformer 2 is constructed as a saturable reactor, and the main magnetic flux of the power transformer 2 can be controlled by the control winding N _C.

Further, in the present embodiment, the transistor Q
Resistor R _{1 to} the _first base is dividing the DC voltage E, R ₂
, The collector is connected to the DC voltage E through the resistor R ₃ , and the emitter is the Zener diode D ₃
Connected to the cathode side of. The cathode of the Zener diode D ₃ is connected to the DC voltage E via the resistor R ₄ , and the anode is connected to the ground. Further, the base of the transistor Q _{2 is connected to} the transistor Q ₂ via the resistor R _5.
1 is connected to the collector, the emitter is connected to the DC voltage E, and the collector is connected to one end of the control winding N _C. In the case of this embodiment, the other end of the control winding N _C is connected to the ground.

The constant voltage operation as the constant voltage transformer device having the above configuration is as follows. First, the emitter of the transistor Q ₁ - potential between the ground is kept by the Zener diode D ₃ to a predetermined voltage. Therefore, for example, when the DC voltage E on the secondary side rises in accordance with the fluctuation of the primary side input voltage V ₁ , the base potential of the transistor Q ₁ divided by the resistors R ₁ and R ₂ rises. . As a result, the current flowing between the base and the emitter increases, and the collector current also increases. This transistor Q ₁
The collector current from flowing through the resistor R ₅ to the base of the transistor Q _2, the base current of the transistor Q ₂ is increased, Therefore, the control current I _C is the collector current of transistor Q ₂ is increased . Since the magnetic circuit of the main magnetic flux of the power transformer 2 is in the saturation region in accordance with the increase of the control current, the voltage transmitted from the primary side to the secondary side is reduced accordingly. On the other hand, if the secondary side DC voltage E fluctuates, the base potential of the transistor Q ₁ drops.
As a result, the current flowing between the base and the emitter is reduced, and the collector current is also reduced. Then, as the collector current decreases, the base current of the transistor Q ₂ also decreases, and as a result, the control current I _C decreases. The DC component that is superimposed on the main magnetic flux decreases in accordance with the decrease in this control current, and the magnetic circuit is controlled to the side that does not saturate, so that the voltage transmitted from the primary side to the secondary side increases. Become. Therefore, if selected depending transistors Q _1, Q _2, resistors R ₁ to R ₅ is a voltage detecting circuit unit, the components such as Zener diode D ₃ to the various conditions, the constant voltage control of the AC output voltage V ₂ It will be possible. Further, in this embodiment, since the power choke coil PCC is provided in the primary side circuit, the power factor is also improved.

The power transformer 2 and the power choke coil PCC of this embodiment may be separately constructed, but as shown in the following FIGS. 9 (a) and 9 (b), a composite type in which both are integrated. Can be configured as a transformer 5,
Accordingly, the number of transformer parts in the circuit of the constant voltage transformer device can be reduced to one, and the leakage magnetic flux can be reduced. FIG. 9A shows an example of the structure of the composite transformer 5 according to this embodiment, which is shown in a front view. For example, in this figure, the winding Ni is wound around the central magnetic leg of the double E-shaped core 5a as shown in the figure, and this double E-shaped core 5a portion corresponds to the power choke coil PCC. A portion corresponding to the power transformer 2 in which the double E-shaped cores 5b and 5c are planarly combined with the double E-shaped core 5a such that their magnetic legs face each other as shown in the drawing, is shown. To be combined. A gap G is formed in the portion where the central magnetic legs face each other as shown in the figure. In the power transformer 2 portion, the primary winding N ₁ is wound around the central magnetic leg on the side of the double E-shaped core 5b, and the secondary winding is wound around the central magnetic leg of the double E-shaped core 5c. N ₂ and tertiary winding N ₃ are wound. Further, as shown in the figure, the control winding N _C is wound around the outer magnetic legs located on the outermost sides.

In the composite transformer 5 shown in the perspective view of FIG. 9B, the double E-shaped core 5a and the double E-shaped core 5a are provided.
The shaped cores 5b are assembled so as to be orthogonal to each other as shown. Then, in the double E-shaped core 5a, the winding Ni is wound around the central magnetic leg to form a power choke coil PCC portion, while the double E-shaped core 5a is formed.
In the shaped core 5b, the winding Ni is attached to the central magnetic leg.
A primary winding N ₁ , a secondary winding N ₂ , and a tertiary winding N ₃ which are connected to the control winding N ₂ are wound around the outermost two outer magnetic legs as shown in the figure. _C is wound around and is configured as a power transformer 2 part. Although not shown, in the composite transformer 4 in the previous embodiment shown in FIG. 5 or 7, the winding Ni and the windings N ₁ , N ₂ and N _{3 are provided.}
It is also possible to obtain a composite transformer compatible with this embodiment by exchanging the winding positions of.

The circuit configuration and the transformer structure in each of the above embodiments are not limited to those shown in the drawings, and various modifications can be made within the scope of the present invention.

[0028]

As described above, in the constant voltage transformer device of the present invention, the control current obtained based on the fluctuation of the secondary side AC voltage is passed through the control winding to change the inductance of the primary side circuit. By providing a saturable reactor that can perform constant voltage control by changing the main magnetic flux of the transformer, the problem of loss due to iron loss and copper loss, which is the case with conventional constant voltage transformer devices, is largely eliminated. Because
The primary-to-secondary AC-AC power conversion efficiency is significantly improved. Further, it also has an effect that the waveform distortion of the output voltage is significantly improved. Further, according to the constant voltage control of the present invention, it is not necessary to provide a capacitor for parallel resonance and winding of a secondary winding, and by using a double E-type core having a low leakage magnetic flux in the transformer portion. Since the shield process is also unnecessary, the steps related to these can be reduced and the part corresponding to the transformer can be downsized, which is very advantageous from the viewpoint of reducing the transformer size and cost. Further, if a power choke coil is provided on the primary side, the power factor is also improved, and it is possible to cope with power source harmonic distortion. Further, if the saturable reactor, the transformer, the power choke coil, etc. are integrated into a single composite transformer, the size of the transformer can be further reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a constant voltage transformer device of the present invention.

FIG. 2 is a circuit diagram showing characteristics of a saturable reactor according to an embodiment.

FIG. 3 is a perspective view showing a specific example of the structure of the transformer in the embodiment.

FIG. 4 is a perspective view showing a specific example of the structure of the saturable reactor in this embodiment.

FIG. 5 is a perspective view showing a specific example of the structure of the composite transformer according to the present embodiment.

FIG. 6 is a circuit diagram showing a constant voltage transformer device as another embodiment.

FIG. 7 is a perspective view showing a specific example of the structure of a composite transformer in another embodiment.

FIG. 8 is a circuit diagram showing a constant voltage transformer device as still another embodiment.

FIG. 9 is a diagram showing a specific example of the structure of a composite transformer in yet another embodiment.

FIG. 10 is a diagram showing a constant voltage transformer device in a conventional example.

11A and 11B are an equivalent circuit diagram and an operation characteristic of a constant voltage transformer device as a conventional example.

[Explanation of symbols]

1 AC power supply 2 Power transformer 3 Saturable reactor N ₁ Primary winding N ₂ Secondary winding N ₃ Tertiary winding Ni Controlled winding N _C Control winding V ₁ Primary side AC input voltage V ₂ Secondary side AC output voltage C smoothing capacitor D _1, D ₂ rectifier diode E DC voltage Q ₁ transistor Q ₂ transistor I _C control current PCC power choke coil

Claims (5)

[Claims] 1. A primary winding supplied with an AC input voltage,
A power transformer unit including a secondary winding and a tertiary winding, in which an AC voltage is excited by an AC input voltage supplied to the primary winding, and an AC voltage excited in the tertiary winding. A direct current voltage detector capable of detecting the level of the direct current voltage, and a saturable reactor including a control winding in which a detection signal of the direct current voltage detector flows as a control current, wherein the saturable reactor is at least the power A controlled winding connected in series with the primary winding or the secondary winding of the transformer section, and the control winding for varying the inductance of the controlled winding are wound. Constant voltage transformer device. 2. A primary winding supplied with an AC input voltage,
A power transformer unit including a secondary winding and a tertiary winding, in which an AC voltage is excited by an AC input voltage supplied to the primary winding, and an AC voltage excited in the tertiary winding. A direct current voltage detector capable of detecting the level of the direct current voltage provided, and a control winding through which a detection signal of the direct current voltage detector flows as a control current, the control winding being provided for the power transformer portion, A constant voltage transformer device characterized in that the main magnetic flux is variable. 3. The constant voltage transformer device according to claim 1, further comprising a power choke coil connected in series to the primary winding. 4. At least one of the power transformer section, the saturable reactor, and the power choke coil is formed with a pair of inner magnetic leg and outer magnetic leg on both outer sides of the central magnetic leg. 4. The constant voltage transformer device according to claim 1, wherein a double E-shaped core is used. 5. The composite transformer in which all or part of the power transformer, the saturable reactor, and the power choke coil are combined and combined as one transformer. The constant voltage transformer device according to claim 4.