JPH02186591A - High-frequency heating device - Google Patents

Abstract

PURPOSE:To enable power supply transformers of the basically same design to cope with a plurality of kinds of magnetrons having different cathode ratings by arranging wirings for cathode heating voltage of the magnetrons while specifying a winding shape and a winding position for obtaining desired induced voltage for heating the cathode. CONSTITUTION:A winding 1 for cathode heating voltage of a magnetron is together wound on the secondary side 5 of a magnet leakage transformer for obtaining anode impression voltage of the magnetron, and thereby the winding 1 is arranged by selecting a winding shape and a winding position in a magnetic field, where a leakage magnetic flux of the magnet leakage transformer is widely distributed, so as interlink a desired amount of the magnetic flux so that desired induced voltage for heating the anode may be obtained. Thereby, the transformers of the basically same design can be applied to a plurality of kinds of magnetrons only different in a cathode characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to a high-frequency heating system having an inverter type power supply, which makes it possible to easily obtain a voltage of an appropriate value for heating the cathode of a magnetron. Regarding equipment.

[Prior art] High-frequency heating devices that perform dielectric heating using microwaves generated by a magnetron are widely used as household cookers, but they have advantages such as being suitable for small size and light weight, and easy output adjustment. In recent years, magnetrons driven by inverter power sources have come into use.

For example, Japanese Utility Model Application Publication No. 166499/1983 discloses that a direct current obtained by rectifying a commercial frequency power source with a rectifier 6 is converted into an alternating current of higher frequency than the commercial power source by opening and closing a switching element 9, as shown in FIG. High-frequency heating is applied to the anode of the magnetron 10 from the secondary side of the step-up transformer ('7U air leakage transformer), which forms a resonant circuit together with the resonant capacitor 8 connected to the negative side. of the device,
A gap is provided in a part of the magnetic core of the step-up transformer 7, and this gap is adjustable. However, this proposal is concerned with generating a high anode voltage and does not mention the winding 1 for the cathode heating voltage wound on the secondary side of the transformer 7.

[Problems to be Solved by the Invention] As in the example described in 1., the conventional technology mainly considers the anode voltage supply of the magnetron, and does not give much consideration to the cathode heating of the magnetron. Generally, large high-frequency currents flow through this type of transformer, so the shape, material, and number of turns of the magnetic core are selected from this perspective.The number of turns of the winding for generating the cathode heating voltage is once or twice
I end up being turned around. When attempting to flow a magnetron cathode heating current through such a winding, the current often ends up being too large or too small relative to the specified current value. For this purpose, conventionally,
The cathode heating current was adjusted by creating inductance by passing beads made of ferrite material through the cathode heating wire, or by coiling the wire to create inductance.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a high-frequency heating device that can easily obtain a voltage of a desired and appropriate value for heating the magnetron cathode.

[Means for Solving the Problems] In order to achieve the above object 1, the present invention includes a winding for the cathode heating voltage of the magnetron on the secondary side of the magnetic leakage transformer for obtaining the voltage applied to the anode of the magnetron. Either wind the wire together, or select the winding shape and winding position so that the leakage flux of the magnetic leakage transformer interlinks with the desired amount of magnetic flux in the widely distributed magnetic field. The electrodes were arranged so that the desired induced voltage could be obtained for cathode heating. this is,
Specifically, a cathode heating voltage is placed on the outside of the iron core of a magnetic leakage transformer so that it can be moved arbitrarily in the axial direction of the iron core and can support the end of the winding at any point in the circumferential direction of the iron core. This can be easily realized by providing a support for the secondary winding.

[Operations] Generally, the number of turns of the winding wire wound around the magnetic core of a transformer is based on an integer number of turns, as shown in Fig. 2. Regardless of whether the magnetic core is E-shaped or U-shaped, ordinary transformers with low leakage magnetic flux are designed based on an integral number of turns. If it is desired to reduce the output voltage of the cathode heating winding by 10%, the number of turns must be reduced by 10%, but this cannot be done if the number of turns of both windings is 1-turn. In the case of high-frequency transformers used for inverter power supplies, changing the number of turns of the -order winding significantly changes the inductance and magnetic flux density of the magnetic core, leading to a complete change in the transformer design. Therefore, if it is possible to obtain the desired cathode heating voltage by making some small changes to the cathode heating winding of the magnetron, then it will be possible to obtain the same basically for multiple types of magnetrons that differ only in the characteristics of the cathode. - It is convenient because the designed transformer can be applied.

According to the present invention, if a winding of any shape is placed at any location in the magnetic field of a magnetic leakage transformer where leakage flux is widely distributed, this winding will be interlinked with any amount of magnetic flux. , a voltage of arbitrary value is induced.

In the case of the Magne-I-Ron power supply, after the magnetron reaches the anode voltage at which it can oscillate, a relatively small increase in the anode voltage causes the Magne-I-Ron anode current to increase significantly;
Furthermore, since there is a risk of runaway due to changes in characteristics associated with an increase in the temperature of the magnetron, it is preferable for the power source to have drooping characteristics, and for this reason, a magnetic leakage transformer was originally used. Therefore, in carrying out the present invention, it is only necessary to provide means for appropriately supporting the cathode heating secondary winding.

[Example] Figures 1 (a), (b), and (c) are explanatory diagrams of main parts of an example of the present invention, in which 1 is a magnetron cathode heating (secondary) winding, and 2 is a magnetic core. It is. Although this is a cross-sectional view, other windings are not shown. These figures show the state of the windings wound around the E-type magnetic core. Based on the induced voltage in the state shown in Figure 1(a), the voltage increases as shown in Figure 1(b), and decreases as shown in Figure 1(c). . FIG. 2 shows a conventional normal winding state.

FIG. 3 is an explanatory view of the main parts of an embodiment of the present invention when a U-shaped magnetic core is used. By providing a support that can selectively fix the cathode heating winding 1 at an intermediate number of turns (not an integer number of turns) on a bobbin (not shown), it is compatible with multiple types of magnetrons that differ only in cathode voltage rating. In addition, in the figure, 2
3 is a magnetic core, 3 is a gap for leaking the magnetic flux of the magnetic core, 4 is a primary winding, and 5 is a winding for anode voltage.

FIG. 4 is a diagram showing the relationship between the number of windings and the output voltage in an embodiment in which U-shaped and E-shaped magnetic cores are used and cathode heating windings according to the present invention are provided. By selectively implementing the number of intermediate windings according to the present invention, it has become possible to adjust the voltage more freely than before. When using an E-type magnetic core, the magnetic flux is divided between the left and right magnetic cores with respect to the central magnetic core, so 0.5 times, 1 time, 1.
Although the voltage change is large at the 5th and 2nd turns, sufficient fine adjustment can be made by using an intermediate number of turns. Also, T.J.
In the case of a type magnetic core, the number of windings is 0.5 or 1.5 times, and the voltage change is large for an integer number of turns. In this case, if the position of the winding is moved in the axial (vertical in the case shown) direction of the magnetic core, for example, the amount of magnetic flux interlinking with the winding will change greatly in areas near the gap between the magnetic cores, causing an induced voltage. can be adjusted.

As explained in ``Effects of the Invention'' 2, according to the present invention, it is now possible to use a power transformer of basically the same general capacity to handle multiple types of magnetrons that differ only in cathode rating. Mass production of high-frequency heating equipment becomes easier, helping to reduce costs.

[Brief explanation of the drawing]

1 - Figures (a), (b), and (c) are explanatory diagrams of the main parts of the embodiment of the present invention, Figure 2 is a diagram showing the conventional normal winding state, and Figure 3
The figure is an explanatory diagram of the main part of an embodiment of the present invention using a U-shaped magnetic core, and FIG. FIG. 5, which is a diagram showing the relationship between the number of times and the output voltage, is a schematic circuit diagram of an example of a conventional inverter-powered high-frequency heating device. 1 Cathode heating winding, 2 Magnetic core, 3 Gap for leaking the magnetic flux of the magnetic core, 4 -th order winding, 5... Anode voltage winding, 6 Rectifier, 7-Jl pressure transformer, 8
・Resonance capacitor, 9 switching element, 10
-Magnetron. Figure 1 (C) 2- Ten thousand thoughts

Claims (1)

[Claims] 1. Convert the direct current obtained by rectifying the commercial power source into alternating current with a higher frequency than the commercial power source using an inverter consisting of a switching circuit, etc., input this alternating current to a magnetic leakage transformer, and use it for heating. In a high-frequency heating device designed to obtain an anode voltage and a cathode heating voltage for a magnetron that generates microwaves, the winding for the cathode heating voltage of the magnetron wound on the secondary side of the magnetic leakage transformer is connected to the magnetic leakage transformer. The winding shape and winding position are selected and arranged so that the leakage magnetic flux of the device interlinks with the desired amount of magnetic flux in a widely distributed magnetic field, and the desired induced voltage is obtained for cathode heating. A high-frequency heating device characterized by being able to 2. A secondary winding for cathode heating voltage is installed outside the iron core of the magnetic leakage transformer, which can be moved arbitrarily in the axial direction of the iron core and can support the winding end at any point in the circumferential direction of the iron core. The high-frequency heating device according to claim 1, further comprising a wire support.