JP4069489B2 - Inverter power source for dual frequency power melting furnace power circuit and power circuit for dual frequency power melting furnace using this inverter power source - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter power source of a power circuit for a dual frequency power melting furnace suitable as a power source for a dual frequency power melting furnace such as a cold crucible melting furnace, and a power circuit for a dual frequency power melting furnace to which the inverter power source is applied. The present invention relates to a power circuit for a dual frequency power melting furnace that is improved so that a power source and a low frequency power source do not affect each other due to different frequencies.
[0002]
[Prior art]
In metal melting by an induction melting furnace, it may be necessary to simultaneously supply high and low frequency AC power to the melting furnace in parallel.
For example, in a cold crucible melting furnace, melting the target metal with a high frequency power component of several tens of KHz while applying a floating force to the target metal with a low frequency power component of several KHz, Advanced functions for higher quality are required.
[0003]
Such a dual frequency power melting furnace power circuit is a parallel resonant inverter power source shown in FIG. 4 (A) or a series resonant inverter power source shown in FIG. 4 (B), which is generally used as a power source for an induction melting furnace or the like. For example, as shown in FIG. 4C (hereinafter referred to as the first conventional example).
In FIG. 4 (A), A is a current source inverter that generates a frequency f, 1 load L, consisting of R and a capacitor C _1, which is a load parallel resonance circuit which resonates at a predetermined frequency f.
In FIG. 4 (B), B is a voltage source inverter that generates a frequency f, 2 is the load L, consisting of R and a capacitor C _2, which is a load series resonance circuit which resonates at a predetermined frequency f.
Here, L is the inductance of the melting furnace coil of the load, and R is an equivalent resistance corresponding to the heat consumption of the load.
The first conventional example shown in FIG. 4C uses a power source shown in FIG. 4A as a power source for generating a high frequency f _H and a low frequency f _L and uses two power sources for common loads L and R. Are supplied in parallel.
In FIG. 4 (C), IH is a high-frequency-side load parallel resonance circuit (the load L, the resonant circuit resonating to the high frequency f _H consisting of R and a capacitor C _IH).
1L is a low-frequency side load parallel resonance circuit (a resonance circuit that resonates at a low frequency f _L composed of loads L, R, and L ₁ and a capacitor C _1L ).
Here, L _I is an inductance that is connected to the low-frequency circuit side that is required when such power sources having different frequencies are connected in parallel to a common load.
In a power supply circuit for a dual frequency power melting furnace, for example, as disclosed in Japanese Utility Model Laid-Open No. 57-201791, a high frequency coil and a low frequency coil are separately provided in the melting furnace, and each power source is individually provided. Means for supplying (hereinafter referred to as a second conventional example) has been proposed.
Furthermore, there is the following as a prior art (hereinafter referred to as a third conventional example) as disclosed in Japanese Patent Application No. 9-42826.
As shown in FIG. 4D, the third conventional example uses the power source shown in FIG. 4B as the power source for generating the high frequency f _H and uses the power source shown in FIG. 4 as the power source for generating the low frequency f _L. Two frequencies are supplied in parallel to the common loads L and R using the power source shown in FIG.
In FIG. 4 (D), 2H at the high frequency side load series resonance circuit (load L, the resonant circuit resonating to the high frequency f _H consisting of R and a capacitor C _2H), L ₁ is the inductance.
[0004]
[Problems to be solved by the invention]
By the way, the above-described conventional apparatus has the following problems in its configuration.
First, in the case of the first conventional example shown in FIG. 4C, there is no means for suppressing the low-frequency current component flowing out from the low-frequency power source toward the inverter A (f _H ) on the high-frequency power source side. There was a problem that the influence on the output of the inverter was large. In this case, since the high-frequency current component flowing out from the high-frequency power source toward the inverter A (f _L ) on the low-frequency power source side is absorbed by the _actions of the inductance L ₁ and the capacitor C _1L of the low-frequency circuit, the inverter The effect on the output of is reduced.
Further, in the case of the second conventional example, there is a problem that it cannot be applied to a normal two-terminal coil melting furnace.
On the other hand, in the case of the third conventional example as shown in FIG. 4D, the low-frequency current component flowing out from the low-frequency power source toward the inverter B (f _H ) on the high-frequency power source side is the capacitor of the high-frequency circuit. Although there is an effect of being cut off by the action of _C2H , there is a problem that the influence on the output of the inverter remains somewhat.
The present invention solves the above-described problems (problems) of the conventional one, and eliminates the possibility that the inverter outputs of the high-frequency and low-frequency power supplies connected in parallel in the two-terminal coil are affected by different frequencies. An object of the present invention is to provide an inverter power source for a dual frequency power melting furnace power circuit and a dual frequency power melting power circuit to which the inverter power is applied .
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the inverter power source of the power circuit for the dual frequency power melting furnace of the present invention is the one according to claim 1 , wherein a voltage source inverter is used, and between the output of the voltage inverter and the melting furnace coil. The resonance circuits are connected to each other in the order of the series resonance circuit, the parallel resonance circuit, and the series resonance circuit, so that at least two resonance circuits are provided .
Further, according to the second aspect of the present invention, a current source inverter is used, and between the output of the current source inverter and the melting furnace coil, the parallel resonance circuit starts, and the series resonance circuit and the parallel resonance circuit in this order. By connecting the resonance circuits, at least two resonance circuits are provided .
According to a third aspect of the present invention, there is provided a power supply circuit for a frequency power melting furnace according to the third aspect of the present invention. The inverter power supply used is applied, and the inverter power supply using the current source inverter according to claim 2 is applied as the other low-frequency power supply.
Moreover, in the thing of Claim 4, in the melting furnace supplied in parallel from a dual frequency power supply, the inverter power supply using the current source inverter of Claim 2 is applied as one high frequency power supply, and the other low frequency power supply is used. As the power source, an inverter power source using the voltage source inverter according to claim 1 is applied.
According to the fifth aspect of the present invention, in the melting furnace supplied in parallel from the two-frequency power source, the inverter power source using the voltage source inverter according to the first aspect is applied as each of the high-frequency power source and the low-frequency power source. And configured.
Further, according to the present invention, the inverter power source using the current source inverter according to claim 2 is applied as a power source for each of the high frequency power source and the low frequency power source in the melting furnace supplied in parallel from the dual frequency power source. And configured.
With such a configuration, the current component that tends to flow out toward the other inverter is cut off or absorbed by the action of a resonance circuit having different frequency characteristics connected in series or in parallel with the other circuit, resulting in a high frequency, low frequency. It is possible to appropriately prevent the inverter output of each frequency from being affected by different frequencies.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings.
First embodiment:
FIG. 1 shows four types of inverter power supply circuits suitable for application to the dual-frequency power melting furnace power supply circuit according to the first embodiment of the present invention. (A), (B), (C), ( Each connection diagram is shown in D).
In the figure, the same reference numerals are used for components that function in the same way as in FIGS. 4A and 4B, and detailed description thereof is omitted.
1 (A) is, after the connection of the parallel resonant circuit 3 to the output of the current source inverter A for generating a predetermined frequency f (resonance circuit which resonates at a predetermined frequency f consisting inductance L ₃ and capacitor C _3), the load It is the 1st circuit structural example of this Embodiment comprised by connecting the series resonance circuit 2. FIG. This is a circuit corresponding to claim 2.
In FIG. 1B, the parallel resonant circuit 3 is connected to the output of the current source inverter A that generates the predetermined frequency f, and then the series resonant circuit 4 (the predetermined frequency f including the inductance L ₄ and the capacitor C ₄ is set. This is a second circuit configuration example of the present embodiment configured by connecting the load parallel resonant circuit 1 after connecting a resonant circuit). This is also a circuit corresponding to claim 2.
FIG. 1C shows a third circuit of the present embodiment configured by connecting the series resonant circuit 4 to the output of the voltage source inverter B that generates the predetermined frequency f and then connecting the load parallel resonant circuit 1. It is a structural example. This is a circuit corresponding to claim 1.
FIG. 1D shows a configuration in which a series resonance circuit 4 is connected to the output of a voltage source inverter B that generates a predetermined frequency f, and then a parallel resonance circuit 3 is connected, and then a load series resonance circuit 2 is connected. This is a fourth circuit configuration example of the present embodiment. This is also a circuit corresponding to claim 1.
[0007]
Second embodiment:
FIG. 2 shows a power supply circuit for a dual frequency power melting furnace according to the second embodiment of the present invention. (A), (B), (C), and (D) are representative four of the present embodiment. It is a connection diagram of two circuit configuration examples.
These are the power source for supplying power and a low frequency f _L supplying a high frequency f _H, the various circuits inverter power supply of a two-frequency power source melting furnace for the power supply circuit shown as the first embodiment according to the present invention are shown below The power supply circuit for the dual-frequency power melting furnace is configured by being applied in combination as described , and the dual-frequency power is supplied in parallel to the common loads L and R from the respective power supply circuits thus configured. .
In FIG. 2, the same reference numerals are used for configurations equivalent to those in FIGS. 4C and 4D, and when each circuit in FIG. 1 is used on the high frequency side, the configuration is selected corresponding to the frequency f _H. Therefore, when the circuits in FIG. 1 are used on the low frequency side, the configuration is selected corresponding to the frequency f _L , so L is added to the end of the reference symbol, and detailed description thereof is omitted.
FIG. 2A is a connection diagram of a power supply circuit for a dual frequency power melting furnace configured using an inverter power supply circuit using the current source inverter shown in FIG. 1A on both the high frequency side and the low frequency side. This is a circuit corresponding to claim 6.
2B shows an inverter power supply circuit using the voltage source inverter shown in FIG. 1C on the high frequency side and an inverter power supply circuit using the current source inverter shown in FIG. 1A on the low frequency side. FIG. 2 is a connection diagram of a power circuit for a dual frequency power melting furnace constructed using This is a circuit corresponding to the third aspect.
FIG. 2C is a connection diagram of a power supply circuit for a dual frequency power melting furnace configured using an inverter power supply circuit using the current source inverter shown in FIG. 1B on both the high frequency side and the low frequency side. This is a circuit corresponding to claim 6.
2 (D) shows an inverter power supply circuit using the voltage source inverter shown in FIG. 1 (D) on the high frequency side and an inverter power supply circuit using the current source inverter shown in FIG. 1 (B) on the low frequency side. FIG. 2 is a connection diagram of a power circuit for a dual frequency power melting furnace constructed using This is a circuit corresponding to the third aspect.
In the present embodiment, in addition to the circuit configurations shown in FIGS. 2A to 2D, various combinations of the circuits shown in FIG.
These configurations are described in claims 4 and 5 of the present application, respectively.
[0008]
FIGS. 3A to 3C are circuit diagrams for explaining the operation of each circuit of the second embodiment shown in FIGS. 2A to 2C, respectively. The horizontal axis represents the frequency f, and the vertical axis represents the resonance circuit impedance Z).
3A to 3C, the parallel resonant circuits 3H and 3L connected in parallel to the inverter output have high impedance values in the vicinity of the respective frequencies f _H and f _L , and series resonant circuit 4H and 4L are connected in series, because in the vicinity of each of the frequency f _H and f _L a low impedance value, but with respect to the basic operation of the power supply circuit is the same as the conventional, with different frequencies There is a big difference in the mutual influence on the inverter output compared with the conventional one.
[0009]
First, FIG. 3A is a diagram showing the operation of the circuit of FIG. 2A. In FIG. 3A, the low-frequency current component that tends to flow out from the low-frequency side to the high-frequency side inverter is It is absorbed by the capacitor C _2H and the parallel resonant circuit 3H (low impedance value in the vicinity of the frequency f _L ), and does not reach the output of the inverter, while trying to flow out from the high frequency side toward the low frequency side inverter. The high-frequency current component is absorbed by the inductance L ₁ and capacitor C _1H of the low-frequency circuit and the parallel resonance circuit 3L (low impedance value near the frequency f _H ) and does not reach the output of the inverter.
[0010]
Next, FIG. 3 (B) is a diagram showing the operation of the circuit of FIG. 2 (B). In FIG. 3 (B), the low frequency current component which is about to flow out from the low frequency side to the high frequency side inverter is the high frequency circuit. This is interrupted by the series resonance circuit 4H (high impedance value in the vicinity of the frequency f _L ) and does not reach the output of the inverter, but also does not affect the output of the inverter on the low frequency side from the high frequency side as described above. .
[0011]
FIG. 3C is a diagram showing the operation of the circuit of FIG. 2C. In FIG. 3C, the low-frequency current component that tends to flow out from the low-frequency side toward the high-frequency side inverter A high-frequency current component that is cut off by the series resonance circuit 4H and further absorbed by the parallel resonance circuit 3H, does not reach the output of the inverter, and tends to flow out from the high-frequency side toward the low-frequency side inverter. The circuit is cut off by a series resonance circuit 4L (high impedance value in the vicinity of the frequency f _H ), and further absorbed by the parallel resonance circuit 3L and does not reach the output of the inverter.
[0012]
Note that although a circuit diagram using a frequency characteristic diagram for explaining the operation of the circuit shown in FIG. 2D is omitted, the effect is as follows.
That is, in FIG. 2D, the low-frequency current component that tends to flow out from the low-frequency side toward the high-frequency side inverter is the low-impedance in the vicinity of the capacitor C _{2H of the} high-frequency circuit and the parallel resonant circuit 3H (frequency f _L). Value) and is blocked by the series resonance circuit 4H (high impedance value near the frequency f _L ), and does not reach the output of the inverter, but flows out from the high frequency side toward the low frequency side inverter. The high-frequency current component is blocked by the series resonant circuit 4L (high impedance value near the frequency f _H ) of the low-frequency circuit and further absorbed by the parallel resonant circuit 3L (low impedance value near the frequency f _H ). It does not reach the output of the inverter.
[0013]
【The invention's effect】
Since the power supply circuit for a dual frequency power melting furnace of the present invention is configured as described above, it has an excellent effect that mutual interference between the high frequency power supply and the low frequency power supply can be eliminated regardless of the type of the inverter power supply. .
[Brief description of the drawings]
FIGS. 1A, 1B, 1C, and 1D are connection diagrams showing various configurations of a first embodiment of a power circuit for a dual frequency power melting furnace according to the present invention, respectively. is there.
FIGS. 2A, 2B, 2C, and 2D are connection diagrams showing various configuration examples of the second embodiment of the power circuit for a dual frequency power melting furnace according to the present invention, respectively. It is.
FIGS. 3A, 3B, and 3C illustrate the operation of each circuit of the second embodiment, FIGS. 2A, 2B, and 2C. FIG.
4A and 4B are general inverter basic power supply circuits, FIG. 4C is a schematic circuit diagram for explaining a conventional dual-frequency power melting furnace power supply circuit, and FIG. It is a schematic circuit diagram explaining the same power supply circuit of a prior art.
[Explanation of symbols]
A: current source inverter B: voltage source inverters f, f _H , f _L : frequency, high frequency and low frequency L, R: inductance and resistance of melting furnace load 1, 1L, 1H: load parallel resonance circuit that resonates at each frequency 2, 2L, 2H: Load series resonance circuits 3, 3L, 3H that resonate at each frequency: Parallel resonance circuits 4, 4L, 4H that resonate at each frequency: Series resonance circuits C ₁ , C _1L , C that resonate at each frequency _1H : Capacitors C ₂ , C _2L , C _2H composing a load parallel resonant circuit: Capacitors C ₃ , C _3L , C _3H composing a load series resonant circuit C ₄ , C _4L , C composing a parallel resonant circuit _4H : Capacitors L ₃ , L _3L , L _3H constituting the series resonance circuit: Inductances L ₄ , L _4L , l _4H constituting the parallel resonance circuit: Inductance L ₁ constituting the series resonance circuit: L of the low frequency load side circuit I Inductance Z: impedance of the resonant circuit

Claims (6)

Using a voltage source inverter, between the output of the voltage source inverter until melting furnace coils, it begins the series resonant circuit, the parallel resonant circuit, by connecting these resonant circuits in the order of the series resonant circuit, at least 2 An inverter power source of a power circuit for a dual frequency power melting furnace, comprising at least one resonance circuit . Using a current source inverter, between the output of the current source inverter to the melting furnace coils, starting from the parallel resonant circuit, the series resonant circuit, in order of the parallel resonance circuit by connecting these resonant circuits, at least two An inverter power supply of a power supply circuit for a dual frequency power melting furnace characterized by comprising the above resonance circuit . In melting furnace which is parallel supplied from the two-frequency power source, as one of the high frequency power source, and applying the inverter power supply with a voltage source inverter according to claim 1, as the other low-frequency power source, a current source inverter of claim 2, wherein A power circuit for a dual-frequency power melting furnace, wherein an inverter power source using a power source is applied . In a melting furnace supplied in parallel from a dual frequency power source , an inverter power source using the current source inverter according to claim 2 is applied as one high frequency power source , and a voltage source inverter according to claim 1 as the other low frequency power source. A power circuit for a dual-frequency power melting furnace, wherein an inverter power source using a power source is applied . In melting furnace which is parallel supplied from the two-frequency power source, high frequency power source, as a power source of each of the low-frequency power source, the two-frequency power source melting furnace, characterized in that the application of the inverter power supply with a voltage source inverter of claim 1, wherein Power supply circuit. In a melting furnace supplied in parallel from a two-frequency power source, an inverter power source using the current source inverter according to claim 2 is applied as each of a high-frequency power source and a low-frequency power source. Power supply circuit.

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