JP2007005151A - Current type inverter device and high-frequency induction heating device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency quenching device employing a current type inverter structure more expedient than serial resonance and capable of eliminating a floating phenomenon of a matching part causing a problem of a conventional current type inverter structure, and effectively and alternately heating heating objects. <P>SOLUTION: This current type inverter device includes first and second current type inverters 21b and 21b' and is so structured as to alternately oscillate the first and second current type inverters. The current type inverter device is provided with: loop circuits 7b and 7b' having D.C. power sources 6b and 6b' in the circuits; two bridge circuits 11b, 12b, 11b' and 12b' connected to the loop circuits and having switching elements 9b and 9b' and reflux diodes 10b and 10b', respectively; lead wires connected to the two bridge circuits, respectively, and connected to the primary side of a matching transformer; and resistors arranged in a line connected to the lead wires and the loop circuits. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a current type inverter device having first and second current type inverters, wherein the first and second current type inverters are alternately oscillated, and the current type inverter device. The present invention relates to a high frequency induction heating apparatus.

  When a heated object such as metal is induction-heated with high quality, a high-frequency induction heating apparatus is employed in which at least two high-frequency induction heating coils are arranged corresponding to the heated object for heating. . In this case, an inverter (circuit) is connected to each of the two high-frequency induction heating coils, and these two high-frequency induction heating coils are arranged at positions close to each other. For this reason, when two high frequency induction heating coils are operated at the same time, interference occurs between them, resulting in a problem that simultaneous oscillation is not successful. Therefore, as one method for eliminating such a problem, so-called “alternate oscillation” is performed in which two inverters are alternately oscillated and two high-frequency induction heating coils are alternately operated.

  As an inverter provided in such a type of high frequency induction heating apparatus that performs alternate oscillation, there are a voltage type inverter and a current type inverter. An example of the voltage type inverter is shown in FIG. 2, and an example of a known technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-299256 (Patent Document 1). On the other hand, examples of current-type inverters include those shown in FIG. 3 and those shown in Japanese Patent Laid-Open No. 9-56171 (Patent Document 2).

  The high frequency induction heating device 1a shown in FIG. 2 includes a first voltage type inverter 2a and a second voltage type inverter 2a ′. Since the first and second voltage type inverters 2a and 2a 'have the same structure, only the structure of the first voltage type inverter 2a will be described below. The same part in 2a ′ is given a dash (′) symbol and its description is omitted.

  A matching transformer 3a is connected to the first voltage type inverter 2a, and this matching transformer 3a is connected (connected) to the high-frequency induction heating coil 5a via a matching capacitor 4a. On the other hand, the first voltage type inverter 2a (the same applies to the second voltage type inverter 2a ′), as shown in FIG. 2, is connected to the loop circuit 7a having a DC power source 6a and the loop circuit 7a in a bridge shape. Capacitor 8a, a pair of bridge circuits 11a and 12a having a switching element 9a and a freewheeling diode 10a, and lead wires 13a and 14a connecting the respective bridge circuits 11a and 12a to the primary side of the matching transformer 3a. Yes. A high frequency induction heating coil 5a is connected to the secondary side of the matching transformer 3a via a matching capacitor 4a. In addition, the two high frequency induction heating coils 5a and 5a ′ of the high frequency induction heating device 1a are arranged close to each other.

  Thus, the first and second voltage type inverters 2a and 2a ′ of the high frequency induction heating apparatus 1a are alternately operated at short intervals, and the switching elements 9a and 9a in the first and second inverters 2a and 2a ′ are operated. By switching the ', the two high-frequency induction heating coils 5a, 5a' alternately perform high-frequency induction heating of the two adjacent parts of the heated object 15 that is the object to be quenched with the power of the desired frequency. It is like that. In other words, by alternately oscillating (alternating operation) the first and second current source inverters 2a and 2a ′, it is possible to effectively heat a required portion of the heated object 15.

  Further, the high frequency induction heating device 1b shown in FIG. 3 includes a first current type inverter 2b and a second current type inverter 2b ′ having a conventional structure. Since the first and second current type inverters 2b and 2b 'have the same structure, only the structure of the first current type inverter 2b will be described below. The same part in 2b ′ is given a dash (′) symbol, and its description is omitted.

  As in the case of the first voltage type inverter 1a shown in FIG. 2, the lead wires 13b and 14b, the matching transformer 3b, the matching capacitor 4b, and the high frequency induction heating coil 5b are connected to the first current type inverter 2b. ing. On the other hand, the first current type inverter 2b (the same applies to the second current type inverter 2b ′) is a pair of a loop circuit 7b having a DC power source 6b and a DC reactor 16b, a switching element 9b and a freewheeling diode 10b. The bridge circuits 11b and 12b and lead wires 13b and 14b that connect the bridge circuits 11b and 12b and the primary side of the matching transformer 3b are configured. In the case of the voltage type inverter 2a, the switching element 9a and the freewheeling diode 10a are juxtaposed as shown in FIG. 2, whereas in the case of the current type inverter 2b, the switching element 9b and the freewheeling current as shown in FIG. The diode 10b is arranged in series. Note that the two high-frequency induction heating coils 5b and 5b ′ of the high-frequency induction heating device 1b are arranged close to each other.

Thus, the first and second current type inverters 2b and 2b ′ of the high frequency induction heating apparatus 1b are alternately operated at short time intervals, and the switching elements 9b and 2b in the first and second inverters 2b and 2b ′ are operated. By switching the operation 9b ′, the two high-frequency induction heating coils 5b and 5b ′ can alternately perform high-frequency induction heating on the two adjacent portions of the object to be heated 15 that is the object to be quenched with the power of the desired frequency. It is supposed to be. In other words, by alternately oscillating (alternating operation) the first and second current source inverters 2b and 2b ′, it is possible to effectively heat a required portion of the heated object.
JP-A-11-299256 JP-A-9-56171

  In the high frequency induction heating apparatus 1a using the first and second voltage type inverters 2a and 2a ′ as shown in FIG. 2, that is, the high frequency induction heating apparatus 1a having the voltage type inverter structure, a freewheeling diode 10a is provided. Since the voltage type inverter on one side is in the ON state and the voltage type inverter on the other side is in the OFF state, for example, from the voltage type inverter in the one side ON state to the other Interference with the voltage-type inverter in the OFF state on the side is unlikely to occur, and therefore the inverter operation is stable. However, since the magnitudes of the currents flowing on the primary side and the secondary side of the matching transformer 3a are different and the currents flowing on the matching capacitor 4a side are extremely large, the matching transformer 3a and the matching capacitor 4a are large and have a large capacity. Therefore, there is a problem that the equipment (device) cannot be made compact and expensive.

  On the other hand, in the high frequency induction heating apparatus 1b using the first and second current type inverters 2b and 2b ′ as shown in FIG. 3, that is, the high frequency induction heating apparatus 1b having a current type inverter structure, Unlike the series resonance structure such as the second voltage type inverters 2a and 2a ', the parallel resonance structure allows the matching unit (matching transformer 3b, matching capacitor 4b, etc.) to be compact. There are the following problems. That is, in the case of the current type inverter structure, since the freewheeling diode 10b is connected in series with the switching element 9b, when the current type inverter on one side oscillates, a dual circuit of the voltage type inverter circuit is formed. When operated according to the concept, the switching element on the other side needs to be turned on, and the impedance viewed from the load side (oscillation side) is minimized, and optimal oscillation is not achieved. Therefore, in the case of a current type inverter, it is necessary to turn off the switching element 9b (or 9b ′) of the current type inverter on the non-oscillating side. The floating state is entered, and all the electric power due to mutual interference is accumulated in the matching capacitor 4b of the other current source inverter. For this reason, the voltage of the matching capacitor 4b is increased, which may result in damage.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to adopt a current type inverter structure which is more advantageous than series resonance, and to solve the problems of the conventional current type inverter structure. It is an object of the present invention to provide an induction hardening apparatus that can eliminate the floating phenomenon of the matching portion and can effectively alternately heat the object to be heated.

In order to achieve the above object, in the present invention, in a current type inverter device having first and second current type inverters, wherein the first and second current type inverters are alternately oscillated,
The first and second current source inverters are respectively
(A) a loop circuit having a DC power supply in the circuit;
(B) two bridge circuits coupled to the loop circuit and each having a switching element and a free-wheeling diode;
(C) a lead wire connected to each of the two bridge circuits and connected to the primary side of the matching transformer;
(D) a resistor provided in a line connected to the lead wire and the loop circuit;
Is prepared.
According to the present invention, in the above-described current type inverter device, the resistor is arranged on either or both of the plus pole and the minus pole of the line.
In the present invention, the first and second current type inverters, and the first and second high frequency induction heating coils to which high frequency power is supplied from the first and second current type inverters via a matching transformer, respectively. The high frequency induction heating is performed on the object to be heated disposed in the vicinity of the first and second high frequency induction heating coils by alternately oscillating the first and second current type inverters. In induction heating equipment,
Each of the first and second current source inverters is respectively
(A) a loop circuit having a DC power supply in the circuit;
(B) two bridge circuits coupled to the loop circuit and each having a switching element and a free-wheeling diode;
(C) a lead wire connected to each of the two bridge circuits and connected to the primary side of the matching transformer;
(D) a resistor provided in a line connected to the lead wire and the loop circuit;
It is made up of.
According to the present invention, in the above-described high-frequency induction heating apparatus, the resistor is disposed on either or both of the positive electrode and the negative electrode of the line.

  According to a first aspect of the present invention, there is provided a current type inverter device having first and second current type inverters, wherein the first and second current type inverters are alternately oscillated. Each of the two current-type inverters is connected to a loop circuit having a DC power source in the circuit, two bridge circuits connected to the loop circuit, each having a switching element and a free-wheeling diode, and each of the two bridge circuits. And a lead wire connected to the primary side of the matching transformer, and a resistor provided in a line connected to the lead wire and the loop circuit. For example, by providing a resistor in the line connected to the loop circuit, the potential of the input terminal of the matching transformer is stabilized, and the circuit configuration of only the resistor is provided in the cut-off state. Since so as to maintain a low potential I can avoid the floating phenomenon of the current type inverter side not oscillate side, it is possible to stabilize the entire circuit system.

  Further, in the present invention according to claim 2, in the above-described current type inverter device, the resistor is arranged on either or either of the plus and minus poles of the line. May not be disposed on both the positive and negative poles of the line, and by providing only on one side, the same effect as described above can be exhibited, and the entire apparatus can be implemented at low cost.

  According to a third aspect of the present invention, each of the first and second current-type inverters includes a loop circuit having a DC power source in the circuit, and is connected to the loop circuit and includes a switching element and a free-wheeling diode. Two bridge circuits, a lead wire connected to each of these two bridge circuits and connected to the primary side of the matching transformer, and a resistor provided in a line connected to the lead wire and the loop circuit Therefore, by providing a resistor in the line connected to the loop circuit, the floating phenomenon of the current type inverter on the non-oscillating side can be avoided, and the entire circuit system Can be stabilized, and effective high-frequency induction heating (alternate heating) of the object to be heated can be performed. In addition, it is possible to provide a high frequency induction heating apparatus including a current type inverter having a simple structure capable of stabilizing the potential of the matching portion (load portion).

  Further, the present invention according to claim 4 is such that the resistor is arranged on either or both of the plus and minus poles of the line, so that the resistor is arranged on the plus and minus poles of the line. It is not necessary to arrange them on both sides, and by providing them only on one side, the same effect as described above can be exhibited, and the whole can be implemented at low cost.

  Hereinafter, a high-frequency induction heating apparatus according to an embodiment of the present invention will be described with reference to FIG. In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals.

  FIG. 1 shows a high-frequency induction heating apparatus 20 according to an embodiment of the present invention. The high-frequency induction heating apparatus 20 is provided in, for example, an induction hardening facility. The high frequency induction heating device 20 includes a first current type inverter 21b and a second current type inverter 21b ′. Since the first and second current type inverters 21b and 21b 'have the same structure, only the structure of the first current type inverter 21b will be described below. The same parts in 21b 'are given a dash (') symbol and their explanation is omitted.

The first current type inverter 21b includes a loop circuit 7b having a DC power source 6b and a DC reactor 16b in the circuit, and a switching element 9b and a free-wheeling diode 10b connected to the loop circuit 7b and connected in series to each other. Two bridge circuits 11b and 12b each having, lead wires 13b and 14b connected to each of the two bridge circuits 11b and 12b and connected to the primary side of the matching transformer 3b, and these lead wires 13b , 14b and the loop circuit 7b are connected to the lines α, β, γ, δ, respectively, and resistors R ₁ , R ₂ , R ₃ , R ₄ . More specifically, the resistor R ₁ is connected between the terminal A on the positive pole side of the loop circuit 7b and the terminal B of the lead wire 14b (line α), and the terminal C on the negative pole side of the loop circuit 7b. A resistor R ₂ is connected between the terminal B of the lead wire 14b (line β) and a resistor R is connected between the terminal D on the positive pole side of the loop circuit 7b and the terminal E of the lead wire 13b (line γ). ₃ is connected, and the resistor R ₄ is connected between the terminal F on the negative pole side of the loop circuit 7b and the terminal E of the lead wire 13b (line δ). Note that the resistance values of these resistors R ₁ , R ₂ , R ₃ , and R ₄ are appropriately set according to the oscillation state.

  Further, as shown in FIG. 1, the first inverter 21b is connected to the primary side of the matching transformer 4 via lead wires 13b and 14b, and the secondary side of the matching transformer 3b is connected in a bridge shape. It is connected to the first high frequency induction heating coil 5b through a capacitor 4b. The high frequency induction heating coil 5b is disposed in the vicinity of the second high frequency induction heating coil 5b 'connected to the second current type inverter 21b', and the first and second current type inverters 21b and 21b 'are arranged. As the alternating oscillation occurs, the object 15 to be heated is induction-heated by the high-frequency induction heating coils 21b and 21b ′.

In the high-frequency induction heating device 20 having such a configuration, when the first and second current type inverters 21b and 21b ′ are alternately oscillated, the switching element 9b (or 9b) of the current type inverter which is not the oscillation side is used. ') Is turned off and the freewheeling diode 10b (or 10b') is turned off, the resistors R ₁ , R ₂ , R ₃ , R ₄ (or R ₁ ', R ₂ ', R ₃ ', R ₄ ′) including the lines α, β, γ, δ (or α ′, β ′, γ ′, δ ′), respectively, stabilizes the potential of the matching portion on the load side, and the matching capacitor 4b (or 4b ′). The amount of accumulated charge is prevented from increasing, and no damage is caused. Therefore, according to the above-described high frequency induction heating apparatus 20, the current type inverters 7b and 7b ′ are provided with the lines α, β, γ, δ and α ′, β ′, γ ′, δ ′, and the resistor R therein. ₁ , R ₂ , R ₃ , R ₄ and R ₁ ′, R ₂ ′, R ₃ ′, R ₄ ′ are simply constructed, but these resistors are provided to provide resistance. Since the electric circuit is configured through the bodies R _{1 to} R ₄ and R ₁ ′ to R ₄ ′, the potential of the input terminals of the matching transformers 3 b and 3 b ′ is stable. Since the circuit configuration is employed, the potential is kept low, so that the floating phenomenon in the matching portion can be avoided, and high-frequency induction heating can be performed relatively inexpensively and with good stability.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the above-described embodiment, the resistors R ₁ , R ₂ , R ₃ , R ₄ and R ₁ ′, R ₂ ′, R ₃ ′, R ₄ ′ are connected to the positive and negative poles of the loop circuits 7 b, 7 b ′. However, even if a resistor is provided only on one side, the above-described effects can be obtained. When configured in this way, it can be implemented inexpensively as a whole. Further, the present invention is not limited to being used as an inverter of a high frequency induction heating device, but can be widely applied to all current type inverters of other devices that perform alternate oscillation.

It is a circuit diagram which shows the structure of the high frequency induction heating apparatus provided with the current type inverter apparatus of this invention. It is a circuit diagram which shows the structure of the high frequency induction heating apparatus provided with the conventional voltage type inverter apparatus. It is a circuit diagram which shows the structure of the high frequency induction heating apparatus provided with the conventional current type inverter apparatus.

Explanation of symbols

2b, 2b 'Current type inverter 3b, 3b' Matching transformer 4b, 4b 'Matching capacitor 5b, 5b' High frequency induction heating coil 6b, 6b 'DC power supply 7b, 7b' Loop circuit 9b, 9b 'Switching element 10b, 10b' Reflux Diode 11b, 12b, 11b ', 12b' Bridge circuit 13b, 14b, 13b ', 14b' Lead wire 16b DC reactor 20 High frequency induction heating device 21b First current type inverter 21b 'Second current type inverter α, β, γ, δ, α ′, β ′, γ ′, δ ′ Lines A, B, C, D, E, F Terminals R ₁ , R ₂ , R ₃ , R ₄ , R ₁ ′, R ₂ ′, R ₃ ', R ₄ ' resistor

Claims (4)

In a current type inverter device having first and second current type inverters, wherein the first and second current type inverters oscillate alternately,
The first and second current source inverters are respectively
(A) a loop circuit having a DC power supply in the circuit;
(B) two bridge circuits coupled to the loop circuit and each having a switching element and a free-wheeling diode;
(C) a lead wire connected to each of the two bridge circuits and connected to the primary side of the matching transformer;
(D) a resistor provided in a line connected to the lead wire and the loop circuit;
A high frequency induction heating device comprising:   2. The current type inverter device according to claim 1, wherein the resistor is disposed on both or either of a plus pole and a minus pole of the line. First and second current type inverters, and first and second high frequency induction heating coils to which high frequency power is supplied from the first and second current type inverters through matching transformers, respectively, In the high-frequency induction heating apparatus configured to perform high-frequency induction heating of the heated object disposed in proximity to the first and second high-frequency induction heating coils by alternately oscillating the first and second current type inverters,
Each of the first and second current source inverters is respectively
(A) a loop circuit having a DC power supply in the circuit;
(B) two bridge circuits coupled to the loop circuit and each having a switching element and a free-wheeling diode;
(C) a lead wire connected to each of the two bridge circuits and connected to the primary side of the matching transformer;
(D) a resistor provided in a line connected to the lead wire and the loop circuit;
A high frequency induction heating apparatus characterized by comprising: The high-frequency induction heating apparatus according to claim 3, wherein the resistor is disposed on either or both of a plus pole and a minus pole of the line.

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