JPH0254033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called self-excited high-frequency transistor inverter device that switches using its own output signal.

For example, the one shown in FIG. 1 is known as a transistor inverter. 1 is a DC power supply, 2,
A transistor 3 switches the output voltage of the DC power supply. A transformer 4 has an input winding 5 consisting of windings ( _5-1 ) and ( _5-2 ), an output winding 6, a base winding 7, and an iron core 8 made of, for example, ferrite. Both terminals of the input winding 5 are connected to the transistors 2 and 3.
It is connected to one pole side of the DC power supply 1 through the collector and emitter of the DC power supply 1, and the intermediate point is connected to the other pole side of the DC power supply 1. The output winding 6 is also adapted to supply a high frequency alternating current voltage to a load 9, such as a fluorescent lamp. Furthermore, both terminals of the base winding 7 are connected to the bases of the transistors 2 and 3. In addition, in FIG. 1, since the load 9 is a fluorescent lamp, the transformer 4 has a filament winding 10,
It has 11. 12 is an inductor for constant current, and 13 is a capacitor for resonance. Since the operation of such a transistor inverter is well known, a detailed explanation will be omitted, but the transistors 2 and 3 are controlled by the signal of the base winding 7, for example.
It switches at a high frequency of 20KHz or higher, and is self-oscillating. Further, the transformer 4 has a leakage inductance, and this leakage inductance is used as a current limiting element of the fluorescent lamp, which is the load 9.

Next, the configuration of the conventional transformer 4 will be explained with reference to FIGS. 2 to 4. The iron core 8 is generally made of ferrite. and,
As the iron core 8, for example, a pair of E-shaped iron cores 20, 2
1 is used, and the input winding 5 is connected to the central leg of the iron core 20.
and a base winding 7, and an output winding 6 and a filament winding 10,
11 is wrapped around it. Further, the leg portions of the E-shaped cores 20 and 21 are abutted against each other, and the length of the gap 23 at the abutting portions is adjusted to obtain a desired leakage inductance. In this type of transformer, the leakage inductance described above can be obtained at high frequencies, such as 20KHz or higher, so the inductance required to obtain the necessary impedance is very small compared to commercial frequencies. Because it's good. That is, the number of turns of the winding can be reduced or the gap length can be made relatively large, and as a result, the leakage inductance relative to the main inductance can be made large. For this reason, in the past, the desired leakage inductance was obtained only by adjusting the number of turns of the winding and the gap length as described above. However, it has become clear that a transistor inverter device using a transformer having such a configuration has the following problems. That is, the conventional transformer 4
As mentioned above, since the leakage inductance is obtained by the length of the gap 23 between the abutting parts of the cores 20 and 21, the leakage magnetic flux (φ ₁ ) is irregularly distributed around the abutting part, and the base The output voltage of the base winding 7 changes depending on the winding position of the winding 7, and the switching of the transistors 2 and 3 may not be performed normally. For example, when the base winding 7 is wound in A, B, and C in Fig. 3, the output voltage of the base winding 7 is the fourth one.
This will be A, B, and C in the diagram. 5A, 5B and 5C show the collector current of the transistor 2 or 3 corresponding to the output voltage of the base winding 7. In the case of A above, the number of linkages with leakage magnetic flux is small, so
A voltage similar to that of the input winding 5 can be obtained, and switching of the transistors 2 and 3 is almost never abnormal. In case (b), the number of linkages with the leakage magnetic flux increases and the phase with the input winding 5 shifts and the output voltage decreases, so the transistor 2 or 3 that should be reverse biased may turn on instantaneously. Abnormal oscillation may occur or transistors 2 and 3 may be destroyed due to thermal runaway due to excessive power loss. In case (c), the phenomenon (b) becomes noticeable. Therefore, in the past, the base winding 7
The winding position was limited, and the degree of freedom in design was limited. Furthermore, as mentioned above, when the leakage magnetic flux (φ ₁ ) interlinks with the windings 5 and 7, this leakage magnetic flux (φ ₁ ) causes eddy current loss, which increases the power loss of the transformer 4. It became clear. This eddy current loss is described in "Leakage Transformer for High Frequency" filed on July 28, 1981. The above-mentioned problem occurs when using a self-oscillation type transistor inverter other than that shown in the first diagram, and when a leakage inductance is obtained by providing a gap even when using a type other than an E-type core.

The present invention has been made to solve the above conventional problems, and provides a transistor inverter device that can increase the degree of freedom in designing the winding position of the base winding and can reduce the power loss of the transformer. The purpose is to

The present invention provides a first core part in which an input winding and a base winding are wound around an iron core made of ferrite or amorphous, and a first core part in which an output winding is wound and assembled with the first core part. a second iron core portion that is joined together to form a closed magnetic path and that forms a gap at an intermediate portion between the input winding, the base winding, and the output winding; the input winding, the base winding, and the output winding; A third portion is provided at an intermediate portion between the winding wire and closer to the first core portion than the above-mentioned gap, and shunts the magnetic flux.
The invention is characterized in that it is configured to include an iron core portion.

In the present invention, since the third core part is provided closer to the first core part than the gap, the leakage magnetic flux, which was conventionally distributed around the gap, can be concentratedly passed through the third core part. As a result, the number of linkages between the base winding and the leakage magnetic flux becomes much smaller, and the voltage and phase of the input winding differ depending on the position of the base winding, and the output voltage also differs. This can be reduced. As a result, the degree of freedom regarding the winding position of the base winding can be increased. Furthermore, since leakage flux interlinking with the input winding and the base winding can be reduced, eddy current loss in the windings can be reduced, and power loss of the transformer as a whole can be reduced.

In the present invention, the core of the transformer includes a pair of E-type cores, each of which can be wound with a winding wire, and a shunt between the center leg and each side leg of the E-type core constituting the first core part. It can be formed by a rod-shaped iron core provided for a purpose. in this case,
The rod-shaped core may be integrally formed with the E-shaped core or may be formed separately. Such products have a simple shape, so they are easy to obtain and inexpensive.
Further, the iron core is formed of a pair of U-shaped iron cores, an I-shaped iron core around which a winding can be wound, and a shunt iron core arranged between this I-shaped iron core and the legs of the U-shaped iron core. can do. In this case as well, the shunt core may be integrally molded with the U-shaped core, or may be molded separately. In addition, the shape of the iron core may be any shape other than those described above, and can be appropriately selected by those skilled in the art.

Further, in the present invention, the transistor inverter may use either one transistor or two or more transistors. The present invention provides sufficient effects in self-excited transistor inverters. However, it operates in a frequency range of, for example, 10 KHz or higher, where a desired leakage inductance can be obtained due to the gap between the butt portions of the iron cores.

Furthermore, although the present invention is suitable for energizing discharge lamps such as fluorescent lamps, it can also be applied to loads other than discharge lamps.

An embodiment of the present invention will be described below with reference to FIGS. 6 and 7. This embodiment is used as a transformer of the one shown in the first figure. Since the explanation regarding FIG. 1 has already been made, it will be omitted here. 30 is an iron core, which includes a first iron core part 31 made of an E-shaped iron core and a second iron core part 31 also made of an E-shaped iron core.
, and rod-shaped third core portions 33 provided between the central leg and each side leg of the first core portion 31. The legs of the first and second cores 31 and 32 are butted against each other to form a closed magnetic path, and a gap 34 is formed between the legs. A well-known spacer can be interposed in the gap 34. In this embodiment, the third core portions 33, 33 may be integrated with the first core portion 31 or may be separate from the first core portion 31. An input winding 5 and a base winding 7 are wound around the first iron core part 31, and an output winding 6 and filament windings 10 and 11 are wound around the second iron core part 32. . 35 and 36 are winding frames.

Next, we will discuss the effect. Since the basic oscillation operation is well known, the explanation will be omitted. The leakage magnetic flux (φ ₂ ) flows intensively through the third iron core portions 33, 33, and the leakage magnetic flux interlinking with the input winding 5 and the base winding 7 is extremely small. For this reason,
A voltage of a predetermined value is induced in the base winding 7 without any phase shift from the voltage of the input winding 5. This fact hardly changes depending on the winding position of the base winding 7. Therefore, the winding position of the base winding 7 can be selected relatively freely, and the degree of freedom in design is large. Furthermore, since there is less leakage magnetic flux interlinking with the input winding 5 and the base winding 7, eddy current is reduced, and power loss of the transformer as a whole is reduced.

FIGS. 8 and 9 show other embodiments. This embodiment can also be applied to the transistor inverter shown in the first diagram. In this embodiment, the iron core 40 includes a first iron core portion 41 consisting of a U-shaped iron core _41-1 and an I-shaped iron core _41-2 , and a U-shaped iron core 41-2.
A second core part 42 consisting of a type core _42-1 and an I-type core ( _42-2 ), and a U shape in the first core part 41.
The tip of the side leg of type I core _41-1 and I type core _41-2
The third iron core portion 43, 4 provided between the end portion of
3. A gap 44 is formed between each leg of the U-shaped cores _41-1 and _42-1 . The third core portions 43, 43 may be formed integrally with the U-shaped core _41-1 ,
It may also be formed separately. In addition, the I-shaped core 41 in the first and second core portions 41 and 42
_-2 and _42-2 may be integrally molded. Other parts in this embodiment that are the same as those in the first embodiment are given the same reference numerals. Further, since the operation of this embodiment is similar to that of the first embodiment, the explanation will be omitted.

As described in detail above, the present invention provides a self-excited high-frequency transistor inverter device in which the iron core of the transformer includes a first core portion around which an input winding and a base winding are wound, and a first core portion around which an output winding is wound. a second iron core part which is combined with the first iron core part to form a closed magnetic path and which forms a gap between the input winding and the base winding and the output winding; Since the structure includes a third core part provided between the base windings and closer to the first core part than the gap, leakage magnetic flux interlinking with the base winding can be reduced, and the base winding The winding position of the base winding can prevent the phase of the output voltage of the base winding from being out of phase with the voltage of the input winding, or the output voltage value of the base winding can be prevented from changing. This allows a greater degree of freedom in design. Furthermore, since there is less leakage magnetic flux interlinking with the winding, eddy current loss in the winding is reduced, and power loss can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of a transistor inverter, Fig. 2 is a partial cross-sectional front view of a conventional transformer used in a transistor inverter, and Fig. 3 is a diagram showing an example of base winding in a conventional transformer. 4 and 5 are voltage and current waveform diagrams illustrating the conventional operation. FIG. 6 is a partially sectional front view showing an example of the transformer of the present invention, and FIG. 7 is a diagram showing the same embodiment. FIG. 8 is a partially sectional front view showing another embodiment of the transformer of the present invention, and FIG. 9 is a perspective view showing the core of the same embodiment. 1...DC power supply, 2, 3...Transistor, 4
...Transformer, 9...Load, 30,40...Iron core, 31,41...First iron core portion, 32,42...
...Second iron core part, 33, 43...Third iron core part.

Claims (1)

[Claims] 1. A transistor that switches a DC voltage; an input winding provided between the output terminal of a DC power source via the collector and emitter of this transistor;
a transformer comprising an output winding, a base winding that is relatively closely coupled to the input winding and outputs a switching signal of the transistor, and an iron core; the iron core of the transformer is connected to the input winding and A first iron core formed by winding the base winding, and a first iron core formed by winding the output winding are combined to form a closed magnetic path, and the input winding and the base a second iron core having a gap formed between the winding and the output winding; and a second iron core between the input winding, the base winding, and the output winding, and from the gap to the first iron core. 1. A high-frequency transistor inverter device comprising: a third iron core portion for a magnetic flux shunt provided on the side of the high-frequency transistor inverter device. 2. The first and second core portions are E-shaped cores each having a winding wound around the center leg, and are butted against the respective side legs and the center leg, and the third
The high frequency transistor inverter device according to claim 1, wherein the iron core is provided between the tip of each side leg and the tip of the central leg in the first iron core. . 3. The first and second core portions each consist of a U-shaped core and an I-shaped core around which a winding is wound and provided between the leg portions of the U-shaped core. The legs and the ends of the I-shaped core are butted together, and the third core is provided between the tip of the U-leg core in the first core and the end of the I-shaped core. A high frequency transistor inverter device according to claim 1, characterized in that the high frequency transistor inverter device is characterized in that: 4. The high frequency transistor inverter device according to claim 3, wherein the I-shaped cores in each of the first and second core portions are integrally molded.