JP4700416B2 - Induction heating apparatus, method thereof, and heating apparatus - Google Patents

Description

  The present invention relates to an induction heating apparatus, a method, and a heating apparatus for induction heating an object to be heated using different frequencies.

  2. Description of the Related Art Conventionally, an induction heating apparatus that supplies electric power of different frequencies to one induction heating coil to induction-heat an object to be heated is known. Such an induction heating apparatus supplies power of two different frequencies to one induction heating coil at the same time, and quenches the uneven heating surface of a heated object such as a gear (for example, Patent Document 1 or Patent Document). 2).

  The thing of patent document 1 has connected the 1st converter which supplies a high frequency, and the 2nd converter which supplies a medium frequency in parallel to one induction coil. In other words, the first converter that supplies high frequency is used as a series resonance circuit, and the medium frequency feedback from the second converter that supplies medium frequency is attenuated by a capacitor that compensates the reactive power of the induction coil in series. Yes. Further, a capacitor is connected in parallel to the second converter to compensate the reactive power of the induction coil, and between the second converter and the common contact of the first converter and the second converter. A configuration is adopted in which a series circuit of a reactor for suppressing high-frequency feedback and a capacitor for additional compensation for compensating reactive power of the reactor is connected in series. The inductance of the reactor that suppresses high-frequency feedback is set to be at least four times larger than the inductance of the induction coil.

  In Patent Document 2, a resonant capacitor is connected in parallel between output terminals of a first high-frequency power supply device that outputs heating power at a low frequency, and an output from the first high-frequency power supply device is used as a high-frequency heating coil. Is connected to the primary side of the first transformer. Further, the output from the second high-frequency power supply device that outputs the heating power at a high frequency is connected to the primary side of the second transformer that supplies the high-frequency heating coil to the high-frequency heating coil through a resonance capacitor connected in series. . Then, the secondary winding of the second transformer is connected in series between the first transformer and the high frequency heating coil, and the second high frequency power supply device is connected to the secondary side of the first transformer. A high frequency bypass capacitor for bypassing the high frequency component is connected in parallel. The heating power is supplied to the high-frequency heating coil while preventing the electric power from the low-frequency first high-frequency power supply device from leaking to the high-frequency second high-frequency power supply device, and the high-frequency second high-frequency power supply. A configuration is adopted in which heating power is supplied to the high frequency heating coil while preventing leakage of power from the device to the first high frequency power supply device having a low frequency.

Japanese Patent No. 3150968 (page 2 right column-page 3 right column, Fig. 3) JP 2002-356715 A (page 4 right column-page 6 right column, FIG. 1)

  By the way, in the conventional induction heating apparatus as described in Patent Document 1 or Patent Document 2 described above, commercial AC power is converted to predetermined DC power by a forward conversion circuit, and further, a predetermined frequency is converted by an inverse conversion circuit. A configuration using a voltage-type inverse conversion circuit and a configuration using a current-type inverse conversion circuit can be appropriately selected as the configuration converted into AC power and supplied. Here, by adopting a configuration using a voltage-type inverse conversion circuit in a configuration for supplying power of two different frequencies, load adaptability is enhanced as compared with a configuration using a current-type inverse conversion circuit. Therefore, it is preferable. That is, even if the object to be heated is heated and the permeability changes by supplying power of two different frequencies to the induction heating coil, the supplied power that varies according to the change in the permeability is changed to the predetermined power. Constant control can be performed quickly and easily. However, in the configuration using the voltage type inverse conversion circuit, a series circuit of a reactor for suppressing high-frequency feedback and a series circuit of an additional compensation capacitor for compensating reactive power of the reactor is connected in series to the resonance circuit on the low frequency side. Therefore, resistance loss at the reactor occurs, and more efficient induction heating is desired.

  In view of such a problem, an object of the present invention is to provide an induction heating apparatus, a method thereof, and a heating apparatus capable of obtaining good induction heating.

  The induction heating device according to the present invention is an induction heating device that supplies electric power of two different frequencies to the induction heating coil to inductively heat an object to be heated, and a secondary winding is connected to the induction heating coil. A transformer, first resonance means for supplying AC power of a predetermined frequency to the induction heating coil via the transformer, and AC power having a frequency different from the frequency of the first resonance means. Second resonance means for supplying to the coil, and the first resonance means converts the supplied DC power into AC power having a predetermined frequency and outputs the AC power to the primary winding of the transformer. A voltage type first reverse conversion means and a series resonance circuit provided between the first reverse conversion means and the primary winding of the transformer to compensate for the reactive power of the transformer and the induction heating coil And the second resonance means A first capacitor for attenuating the frequency component to be fed back, wherein the second resonance means converts the supplied DC power into AC power having a frequency lower than the frequency converted by the first inverse conversion means. Voltage-type second reverse conversion means for outputting to the secondary winding of the transformer, and a series resonance circuit provided on the output side of the second reverse conversion means to form the transformer and the induction heating A second capacitor that compensates for the reactive power of the coil, a bypass capacitor that is connected to the secondary winding of the transformer and bypasses the frequency component from the first inverse converter, and is connected in series to the bypass capacitor. And a reactor for attenuating a frequency component fed back from the first resonance means in the series resonance circuit by constituting a bypass capacitor and a series resonance circuit.

  In the present invention, the first reverse conversion means of voltage type which converts the supplied DC power into AC power of a predetermined frequency and outputs the secondary winding to the primary winding of the transformer connected to the induction heating coil. And the primary winding of the transformer is provided with a first capacitor constituting a series resonance circuit to constitute a first resonance means, and the first capacitor converts by the first inverse conversion means The frequency component fed back from the second resonance means that supplies AC power having a frequency different from the frequency is attenuated, and the reactive power of the transformer and the induction heating coil is compensated, so that the first resonance means generates alternating current of a predetermined frequency. Electric power is supplied to the induction heating coil to cause induction heating. In addition, a series resonance circuit is configured on the output side of the voltage-type second inverse conversion means that converts supplied DC power into AC power having a frequency different from that of the first resonance means and outputs it to the secondary winding of the transformer. A second capacitor is provided, the reactive power of the transformer and the induction heating coil is compensated by the second capacitor, and AC power of a predetermined frequency is supplied from the second resonance means to the induction heating coil for induction heating. . A bypass capacitor connected to the secondary winding of the transformer and bypassing the frequency component from the first inverse conversion means and a reactor constituting the series resonance circuit are connected in series to the bypass capacitor. The frequency component fed back from the first resonance means is attenuated.

  As a result, the inductance of the reactor is set so that the series circuit of the reactor and the bypass capacitor constituting the series resonance circuit has a resonance frequency corresponding to the frequency of the AC power supplied from the first resonance means. The impedance of the series circuit of the reactor and the bypass capacitor approximates the resistance value of the reactor, which has greatly decreased with respect to the reactance of the bypass capacitor. And, by providing a reactor whose reactance is significantly lower than the impedance that becomes the reactance of the bypass capacitor, the feedback current can be greatly suppressed with respect to the load current flowing through the induction heating coil, so if a reactor with a small reactance is provided Good. This makes it possible to use, for example, a conductor as a reactor having a small reactance, simplifying the configuration, reducing the load on the reactor connected in series with the second capacitor in order to attenuate the feedback, and further omitting it. The occurrence of resistance loss due to the feedback blocking reactor connected in series with the second capacitor is suppressed and the possibility of heat generation is also prevented. Therefore, for example, measures to respond to fluctuations when the load fluctuates due to changes in permeability due to heating of the object to be heated by induction heating, or changes in the shape, material, quenching state, etc. of the object to be heated. Inductive heating control using voltage-type inverse conversion means with good load applicability is obtained, and frequency synchronization control of AC power supplied from the second resonance means is stable by reducing mutual interference In addition, resistance loss is reduced with a simple configuration, and efficient induction heating can be easily obtained.

  In the present invention, the secondary winding of the transformer has a plurality of split windings connected in series, and the second resonance means is configured such that the series resonant circuit of the bypass capacitor and the reactor is split. It is preferable that the connection point of the winding is connected in series with the split winding. As a result, the secondary winding of the transformer is configured by connecting a plurality of split windings in series, and the series resonant circuit of the bypass capacitor and the reactor is connected in series with these split windings at the connection points of the split windings. Since they are connected, for example, by grounding at the connection point of the divided winding, the ground potential is reduced corresponding to the division ratio, and damage due to discharge in the transformer is prevented. Furthermore, the voltage drop in the series resonance circuit of the bypass capacitor and the reactor can be set small, and the feedback voltage from the first resonance means is reduced in accordance with the reduction in the voltage drop, so that the feedback is reduced. The reactor load that needs to be connected in series with the second capacitor to form a series resonant circuit is greatly reduced, and the feedback is blocked by stray inductance in the bus bar for supplying AC power from the second resonant means. This makes it possible to simplify the configuration by omitting the reactor, suppress the occurrence of resistance loss, and further prevent the possibility of heat generation in the reactor.

  In the present invention, the second resonance means includes a primary winding connected in series to the second capacitor on the output side of the second inverse conversion means, and a secondary winding connected to the second resonance means. The second winding of the transformer is connected in parallel to the series resonant circuit of the bypass capacitor and the reactor connected in series to the divided winding at a connection point of the divided winding, and the second winding It is preferable that the transformer includes a transformer that converts the impedance of the AC power output from the inverse conversion means into a predetermined value. As a result, the primary winding is connected in series with the second capacitor to the output side of the second inverse conversion means, and the secondary winding is connected to the connection point of the split winding in the secondary winding of the transformer. A series transformer is connected to the series resonance circuit of the bypass capacitor and the reactor in parallel with these divided windings, and a transformer is provided in the second resonance means, and the alternating current output from the second inverse conversion means by the transformer. Since the impedance of the power is converted to a predetermined value, it becomes easy to supply the AC power from the first resonance means and the AC power from the second resonance means in synchronization with a state in which the frequencies are superimposed. Good induction heating can be easily obtained.

  Furthermore, in the present invention, the bypass capacitor is preferably configured to include a plurality of divided capacitors connected in series and connected to each other at ground. As a result, a plurality of split capacitors are connected in series with their connection points grounded to form a bypass capacitor, so that the voltage drop at both ends in the series circuit of the bypass capacitor and the reactor becomes extremely small. The feedback voltage from the first resonance means is reduced, the reactor load that needs to be connected in series with the second capacitor to reduce feedback is greatly reduced, and AC power is supplied from the second resonance means Therefore, even the stray inductance in the bus bar prevents the feedback of the frequency component from the first resonance means, simplifies the configuration by omitting the reactor, suppresses the occurrence of resistance loss, and prevents the possibility of heat generation in the reactor.

  In the present invention, the reactor is a conductor that connects the bypass capacitor to the secondary winding of the transformer, and series resonance corresponding to the frequency of AC power supplied by the bypass capacitor by the first resonance means. It is preferable that the frequency inductance is set to be set. Thus, the bypass capacitor is a conductor connected to the secondary winding of the transformer, and the conductor is set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied from the bypass capacitor by the first resonance means. Therefore, the reactor is configured as a bus bar provided with a bypass capacitor circuit for bypassing the frequency component from the first resonance means, and the reactance with respect to the impedance that becomes the reactance of the bypass capacitor is configured. In order to reduce the feedback, the feedback current of the frequency component from the first resonance means can be satisfactorily prevented and the feedback is reduced. The reactor load that must be connected in series with the capacitor is large. The stray inductance in the bus bar for supplying AC power from the second resonance means is also prevented from returning the frequency component from the first resonance means, and the configuration can be easily simplified by omitting the reactor. The occurrence of resistance loss is easily suppressed with a simple configuration, and the possibility of heat generation in the reactor is easily prevented.

  And in this invention, the said conductor is set as the structure provided with a pair of electroconductive board respectively connected in series with respect to the said bypass capacitor so that a plane may oppose through a predetermined | prescribed space | interval through the same shape. It is preferable. Thereby, simplification of the configuration, suppression of the occurrence of resistance loss, and prevention of heat generation in the reactor can be easily obtained with a simple configuration.

  Furthermore, in the present invention, the pair of conductive plates are arranged to face each other with a gap set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means by the bypass capacitor. It is preferable that As a result, a simple configuration in which a pair of conductive plates are arranged opposite to each other with a gap set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means by the bypass capacitor. Simplification, suppression of resistance loss, and prevention of heat generation in the reactor can be easily obtained.

  The induction heating apparatus of the present invention is an induction heating apparatus that supplies electric power of two different frequencies to an induction heating coil to inductively heat an object to be heated, and includes a plurality of divided windings connected in series. A transformer having a secondary winding connected to the induction heating coil, first resonance means for supplying AC power of a predetermined frequency to the induction heating coil via the transformer, and Second resonance means for supplying AC power having a frequency different from the frequency to the induction heating coil, and the first resonance means converts the supplied DC power to AC power having a predetermined frequency. A voltage type first reverse conversion means for outputting to the primary winding of the transformer, and a series resonance circuit provided between the first reverse conversion means and the primary winding of the transformer to form the transformer Compensation of the reactive power of the induction heater and the induction heating coil And a first capacitor for attenuating a frequency component fed back from the second resonance means, wherein the second resonance means converts the supplied DC power by the first inverse conversion means. A voltage-type second reverse conversion means for converting the alternating current power into a lower frequency and outputting between the divided windings in the secondary winding of the transformer, and an output side of the second reverse conversion means; And a second capacitor that constitutes a series resonance circuit and compensates for the reactive power of the transformer and the induction heating coil, and is connected in series with the divided windings between the divided windings, and is connected in series. A bypass circuit comprising a series circuit of a plurality of divided capacitors whose connection points are grounded, suppressing a frequency feedback from the first resonance means, and bypassing a frequency component from the first inverse conversion means; The And said that there were pictures.

  In the present invention, the first reverse conversion means of voltage type which converts the supplied DC power into AC power of a predetermined frequency and outputs the secondary winding to the primary winding of the transformer connected to the induction heating coil. And the primary winding of the transformer is provided with a first capacitor constituting a series resonance circuit to constitute a first resonance means, and the first capacitor converts by the first inverse conversion means The frequency component fed back from the second resonance means that supplies AC power having a frequency different from the frequency is attenuated, and the reactive power of the transformer and the induction heating coil is compensated, so that the first resonance means generates alternating current of a predetermined frequency. Electric power is supplied to the induction heating coil to cause induction heating. In addition, the voltage type second that converts the supplied DC power into AC power having a frequency different from that of the first resonance means and outputs the AC power between the plurality of divided windings connected in series in the secondary winding of the transformer. A second capacitor constituting a series resonance circuit is provided on the output side of the inverse conversion means, and the reactive power of the transformer and the induction heating coil is compensated by the second capacitor so that the second resonance means has a predetermined frequency. AC power is supplied to the induction heating coil to cause induction heating. A bypass circuit that includes a series circuit of a plurality of divided capacitors that are connected in series and that are connected to each other at ground is provided to bypass the frequency component from the first inverse conversion means, and is divided in the secondary winding of the transformer. By connecting the divided windings in series between the windings, the feedback of the frequency from the first resonance means is suppressed.

  As a result, the bypass circuit constituting the series resonance circuit has the reactor inductance set to a resonance frequency corresponding to the frequency of the AC power supplied from the first resonance means, so that the connection point is grounded. The voltage drop across the bypass circuit with a series circuit in which a plurality of split capacitors are connected in series is extremely small, and the impedance of the bypass circuit is greatly reduced with respect to the combined reactance of the series circuit of split capacitors. It will be approximated to. And, by providing a reactor whose reactance is significantly lower than the combined impedance that is the combined reactance of the series circuit of the divided capacitors, the feedback current is greatly suppressed with respect to the load current flowing through the induction heating coil, so the reactance is small A reactor may be provided. This makes it possible to use, for example, a conductor as a reactor having a small reactance, simplifying the configuration, reducing the load on the reactor connected in series with the second capacitor in order to attenuate the feedback, and further omitting it. The occurrence of resistance loss due to the feedback blocking reactor connected in series with the second capacitor is suppressed and the possibility of heat generation is also prevented. Therefore, it is possible to obtain a good induction heating control using a voltage-type inverse conversion means having a good load applicability, which is applicability to load fluctuations, for example, by heating the object to be heated by induction heating and changing the magnetic permeability. The frequency synchronization control of AC power supplied from the second resonance means due to the reduction of mutual interference is stabilized, and efficient induction heating with reduced resistance loss can be easily obtained with a simple configuration.

  And in this invention, it is preferable to set the said bypass circuit as the structure set to the inductance used as the series resonance frequency corresponding to the frequency of the alternating current power supplied by a 1st resonance means. As a result, the bypass circuit is set in the inductance having the series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means, so that the combined impedance that becomes the combined reactance of the series circuit of the divided capacitors is reduced. As the reactance greatly below, the floating inductance of the bus bar that provides a bypass circuit for bypassing the frequency component from the first resonance means is used, and the feedback current is greatly suppressed with respect to the load current flowing through the induction heating coil, which is good Thus, the feedback of the frequency component from the first resonance means is obtained, the reactor load that needs to be connected in series with the second capacitor to reduce the feedback is greatly reduced, and the AC power from the second resonance means is reduced. The frequency from the first resonance means even in the stray inductance in the bus bar for supplying Min feedback is prevented, along with simplification of the construction by omission of the reactor can be easily obtained, the occurrence of resistance loss is easily suppressed by a simple configuration, up for heat generation in the reactor it is also easily prevented.

  In the present invention, the bypass circuit includes a first conductive plate connected between one end of the series circuit of the split capacitors and one end of one split winding in the secondary winding of the transformer; A second conductive plate connected between the other end of the series circuit of the divided capacitors and one end of the other divided winding in the secondary winding of the transformer, and arranged in parallel via a predetermined gap; It is preferable to have a configuration including Thus, the first conductive plate is connected between one end of the series circuit of the split capacitor and one end of one of the split windings of the secondary winding of the transformer, and the other end of the series circuit of the split capacitor A second conductive plate is connected between one end of the other divided winding in the secondary winding of the transformer, and the first conductive plate and the second conductive plate are arranged in parallel with a predetermined gap. Therefore, the bypass circuit is set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means with a simple configuration, thereby simplifying the configuration and generating resistance loss. Suppression and prevention of heat generation in the reactor can be easily obtained.

  Furthermore, in the present invention, the bypass circuit includes the first capacitor through a gap set to an inductance having a series resonance frequency with respect to the frequency of the AC power supplied from the first resonance means by the series circuit of the split capacitors. It is preferable that the conductive plate and the second conductive plate are arranged to face each other. Thus, by adjusting the gap between the first conductive plate and the second conductive plate, the series resonance frequency corresponding to the frequency of the AC power that the bypass circuit supplies by the first resonance means can be easily obtained. It is set to inductance, and simplification of the configuration, suppression of resistance loss, and prevention of heat generation in the reactor can be easily obtained.

  In the present invention, it is preferable that the second resonance unit supplies AC power having a frequency lower than the frequency of AC power supplied by the first resonance unit. As a result, the AC power having a frequency lower than the frequency of the AC power supplied by the first resonance means is supplied from the second resonance means. Therefore, as a feedback prevention of the high frequency component, the division capacitor for bypassing the high frequency component is bypassed. Since it is sufficient to set the reactance to be much lower than the impedance of the series circuit, feedback of high frequency components is suppressed by effectively using the stray inductance by the bus bar of the circuit in which the bypass circuit is provided without providing a reactor as the bypass circuit. The Rukoto. Therefore, easy simplification of configuration, suppression of resistance loss, and prevention of heat generation in the reactor can be effectively obtained.

  In the present invention, forward conversion means for converting AC power into the DC power and outputting the same is provided, and the first reverse conversion means and the second reverse conversion means are output from the forward conversion means. Preferably, the DC power is converted into AC power having a predetermined frequency. With this configuration, since the voltage-type first inverse conversion unit and the second inverse conversion unit are used, the voltage-type first inverse conversion unit and the second inverse conversion unit respectively supply AC power having a predetermined frequency. As the direct-current power to be converted into the direct-current power, the forward conversion means for supplying the direct-current power to the first resonance means and the second resonance means by converting the alternating-current power into the direct-current power and supplying it from the forward conversion means. Means are shared and further configuration simplification is obtained.

  The heating apparatus according to the present invention includes an induction heating coil that induction-heats an object to be heated, and supplies the electric power of two different frequencies to the induction heating coil to inductively heat the object to be heated. And an induction heating device according to any one of the above.

  In the present invention, the induction heating coil for induction heating the object to be heated is supplied with electric power of two different frequencies from the induction heating device according to any one of claims 1 to 13 to induction heat the object to be heated. Let For this reason, efficient induction heating can be easily obtained with a simple configuration.

  In the present invention, the induction heating device has a frequency that is converted by the first reverse conversion means of 50 kHz or more and 1 MHz or less, and a frequency that is supplied by the second reverse conversion means is 1 kHz or more and 50 kHz or less. The induction heating coil is preferably configured to induction-heat a metal material having irregularities on the surface as the object to be heated. As a result, the first reverse conversion means converts it to AC power having a frequency of 50 kHz or more and 1 MHz or less, the second reverse conversion means converts it to AC power having a frequency of 1 kHz or more and 50 kHz or less, and supplies it to the induction heating coil. Then, since the metal material having unevenness on the surface is heated as an object to be heated, the surface of the metal material is well quenched by AC power from the first resonance means, and the inside of the metal material is the second resonance. It is well quenched with AC power from the means and the metal material is heat treated well.

  The induction heating method of the present invention uses the induction heating device according to any one of claims 1 to 13, and uses an AC power of a predetermined frequency output from the first resonance means and the second resonance. The object to be heated is induction-heated by superimposing or switching the alternating-current power output from the means and having a frequency different from the frequency of the first resonance means to the induction heating coil.

  According to the present invention, in the induction heating device according to any one of claims 1 to 13, the AC power having a predetermined frequency output from the first resonance means and the second resonance means at a frequency different from this frequency. The AC power to be output is superposed or switched and supplied to the induction heating coil to cause the object to be heated to be induction heated. Thus, the object to be heated is induction-heated efficiently and easily with an induction heating device having a simple configuration.

  Hereinafter, a heating device according to an embodiment of the present invention will be described with reference to the drawings. In addition, although the heating apparatus in this Embodiment demonstrates the structure which carries out the induction heating process of the to-be-heated object, for example using two different types of frequencies, it combines the several induction heating apparatus, and is AC power of several frequencies. May be supplied to an induction heating coil connected to an induction heating device to perform induction heating. In addition, the object to be heated is a metal material with a complex shape having a plurality of irregularities on its surface, such as gears, screws, bolts, nuts, etc., and a cylindrical shape that has irregular diameters in the axial direction with different diameter dimensions such as a shaft. Any of these members and composite materials in which different materials are laminated can be used. FIG. 1 is a circuit diagram showing a schematic configuration of the induction heating apparatus in the present embodiment.

[Configuration of heating device]
In FIG. 1, reference numeral 10 denotes a heating device, and this heating device 10 is an apparatus that induction-heats and quenches an object to be heated 11 having an uneven surface to be heated, such as a gear, using two different frequencies. is there. The heating device 10 includes an induction heating coil 100 that induction-heats the article 11 to be heated, and an induction heating device 200 that supplies AC power of two different frequencies to the induction heating coil 100.

  Induction heating coil 100 is connected to induction heating device 200. And the induction heating coil 100 induction-heats the to-be-heated object 11 by supplying the alternating-current power of 2 types of different frequency from the induction heating apparatus 200 by superimposing or switching suitably.

  The induction heating device 200 appropriately converts commercial AC power into AC power having two different frequencies and supplies the AC power to the induction heating coil 100. The induction heating apparatus 200 is a first transformer 210 as a transformer, and a first frequency that is induction-heated by supplying high-frequency AC power having a predetermined frequency, for example, a frequency of 50 kHz to 1 MHz, to the induction heating coil 100. A resonance means 220; a second resonance means 230 for inductively heating the induction heating coil 100 by supplying an AC power having a frequency lower than the frequency of the first resonance means 220, for example, a medium frequency of 1 kHz to 50 kHz; And a control means (not shown) that performs control to appropriately supply AC power from the first resonance means 220 and the second resonance means 230, respectively.

  The first transformer 210 is connected to the first resonance means 220 and the second resonance means 230 and is connected to the induction heating coil 100, and supplies AC power having a predetermined frequency to the induction heating coil 100. The first transformer 210 has a small self-inductance, for example. The first transformer 210 has a first divided winding 212A that is a divided winding connected in series constituting the secondary winding 212 and a second that is a divided winding. Each of the divided windings 212B is wound once, and the combined inductance value of the first divided winding 212A and the second divided winding 212B is substantially the same as the inductance value of the induction heating coil 100. Is set. In the first transformer 210, both ends of the series circuit of the first divided winding 212 </ b> A and the second divided winding 212 </ b> B that are both ends of the secondary winding 212 are connected to the induction heating coil 100. That is, the induction heating coil 100 is connected between one end side of the first split winding 212A and the other end side of the second split winding 212B.

  The first resonance unit 220 includes a first oscillation unit 221, a second transformer 222, and a first capacitor C1. The first oscillating means 221 includes a first converter 221A as a forward converting means, a first smoothing capacitor Cf1, and a first inverter 221B as a first inverse converting means. The first converter 221A is a forward conversion circuit using, for example, various bridge rectifier circuits, and is connected to the commercial AC power source e to convert the AC power of the commercial AC power source e into DC power. The converted DC power is appropriately smoothed through the first smoothing capacitor Cf1 and output to the first inverter 221B. The first inverter 221B is a voltage-type inverter such as a full-bridge type, for example, and converts DC power input via the first smoothing capacitor Cf1 into the above-described high-frequency AC power having a predetermined frequency. The primary winding 222A of the second transformer 222 is connected in series between the output terminals of the first inverter 221B. The second transformer 222 converts high-frequency AC power into a predetermined impedance. The second transformer 222 forms a series resonance circuit with the first capacitor C1 and the induction heating coil 100.

  The first resonance means 220 includes a series circuit of the first capacitor C1 and the primary winding 211 of the first transformer 210 between the output terminals of the secondary winding 222B of the second transformer 222. It is configured to be connected in series. That is, the first capacitor C1 enters a series resonance state by a predetermined high-frequency AC power output from the first inverter 221B and supplied through the second transformer 222, and is heated by the induction heating coil 100. 11 is induction-heated. The first capacitor C1 compensates for the reactive power of the first transformer 210 and the induction heating coil 100, and has a medium frequency of AC power fed back from the second resonance means 230 by the first transformer 210. Attenuates the component. Then, as described above, the first resonance means 220 supplies high-frequency AC power having a frequency of 50 kHz to 1 MHz to the induction heating coil 100 via the first transformer 210, and the first capacitor C 1 The object to be heated 11 is induction-heated by series resonance. Here, when the frequency is lower than 50 kHz, there is a possibility that good quenching of the object to be heated 11 whose surface to be heated, particularly the gear, is uneven cannot be obtained. On the other hand, if it is higher than 1 MHz, it is difficult to obtain good induction heating. For this reason, it is preferable to set the frequency supplied by the first resonance means 220 in the range of 50 kHz to 1 MHz.

  The second resonance means 230 includes a second oscillation means 231, a second capacitor C 2, a third transformer 232 as a transformer, and a bypass circuit 233. Similarly to the first resonance means 220, the second oscillation means 231 includes a second converter 231A, a second smoothing capacitor Cf2, and a second inverter 231B. The second converter 231A is a forward conversion circuit using, for example, various bridge rectifier circuits, and is connected to the commercial AC power source e to convert the AC power of the commercial AC power source e into DC power. The converted DC power is appropriately smoothed through the second smoothing capacitor Cf2 and output to the second inverter 231B. The second inverter 231B is, for example, a voltage source inverter, and converts the DC power input via the second smoothing capacitor Cf2 into the above-described medium frequency AC power having a predetermined frequency. The third transformer 232 converts the low-frequency AC power into a predetermined impedance. In the third transformer 232, the first capacitor C1 and the induction heating coil 100 constitute a series resonance circuit.

  In the second resonance means 230, a series circuit of the second capacitor C2 and the primary winding 232A of the third transformer 232 is connected between the output terminals of the second inverter 231B. The second capacitor C2 includes an inductance of the bus bar 234 that is a line in the circuit between the output terminal of the second inverter 231B and the primary winding 232A of the third transformer 232, and an equivalent inductance of the induction heating coil 100. Thus, a series resonance circuit that performs series resonance is configured. Further, the secondary winding 232B of the third transformer 232 has both ends connected to the connection point of the first split winding 212A and the second split winding 212B in the secondary winding 212 of the first transformer 210, That is, the secondary winding 232B is connected in series between the first split winding 212A and the second split winding 212B. Note that the bus bar 234 prevents high-frequency feedback from the first resonance means 220, that is, prevents high-frequency current from entering the second inverter 231B due to its stray inductance.

  Further, the bypass circuit 233 includes a bypass series circuit C3 as a bypass capacitor of the first divided capacitor C3A and the second divided capacitor C3B, which are divided capacitors connected in series. The first split capacitor C3A and the second split capacitor C3B are of the same standard. Further, in the bypass series circuit C3, the connection point between the first divided capacitor C3A and the second divided capacitor C3B is grounded. In the bypass circuit 233, both ends of the bypass series circuit C3 are connected to the connection point of the first divided winding 212A and the second divided winding 212B of the first transformer 210, that is, the first divided winding 212A and the first divided winding 212A. It is connected in series between the two-split windings 212B in parallel to the secondary winding 232B of the third transformer 232 by a conductor L1 as a reactor that is a bus bar. That is, the bypass circuit 233 includes a bypass series circuit C3 and a conductor L1 connected in series to the bypass series circuit C3. The conductor L1 causes the bypass series circuit C3 to be connected to the secondary winding 212 of the first transformer 210. Connected to bypass the high frequency component from the first resonance means 220. The conductor L1 forms a series resonance circuit with the bypass series circuit C3, and attenuates the high frequency component fed back from the first resonance means 220. The conductor L1 is opposed to a state in which the first conductive plate L1A and the second conductive plate L1B, which are a pair of conductive plates formed of, for example, a copper plate in the same flat shape with a predetermined dimension, face each other with a predetermined gap. Arranged and configured. The floating inductance L of the conductor L1 is a length dimension l [mm], a width dimension W [mm], a thickness dimension D [mm], and a gap plate of the first conductive plate L1A and the second conductive plate L1B. When the gap G is [mm], it is expressed by the following formula 1.

(Equation 1)
L = 1.26 × 10 ⁻³ × 1 × (G / W) [μH / mm]

  The inter-plate gap G of the conductor L1 is set to a state that becomes an inductance L of the conductor L1 that is a series resonance point of the bypass series circuit C3 and the conductor L1 with a high-frequency component from the first resonance means. For example, the frequency f1 of the high-frequency AC power supplied by the first resonance means 220 is 200 kHz, and the combined capacitance C of the first divided capacitor C3A and the second divided capacitor C3B, which is the capacitance of the bypass series circuit C3, is 50 μF. If the length dimension 1 of the first conductive plate L1A and the second conductive plate L1B is 500 mm and the width dimension W is 300 mm, the inductance L of the conductor L1 is calculated by the following equation (2).

(Equation 2)
L = 1 / (ω ² × C)
= 0.0127 μH
ω: 2π × f1
C: (C3A × C3B) / (C3A + C3B)
C3A: Capacitance of the first divided capacitor C3A C3B: Capacitance of the second divided capacitor C3B

  Therefore, for example, the inter-plate gap G between the first conductive plate L1A and the second conductive plate L1B having the length dimension l of 500 mm and the width dimension W of 300 mm is calculated by the following equation (3).

(Equation 3)
G = L × W / (1.26 × 10 ⁻³ × l)
= 0.0127 × 300 / (1.26 × 10 ⁻³ × 500)
= 6 [mm]

  And the 2nd resonance means 230 supplies the to-be-heated material 11 to induction heating by the serial resonance of the 2nd capacitor | condenser C2 by supplying the alternating current power of the frequency of 1 kHz or more and 50 kHz or less to the induction heating coil 100. Here, when the frequency is lower than 1 kHz, it may be difficult to obtain good induction heating. On the other hand, when it becomes higher than 50 kHz, there is a possibility that good induction heating over the inside of the article to be heated 11 cannot be obtained. Therefore, the frequency supplied by the second resonance unit 230 is preferably 1 kHz or more and 50 kHz or less.

  The control unit controls the operations of the first resonance unit 220 and the second resonance unit 230. This control means includes operation means (not shown) for setting the magnitude of AC power supplied from the first resonance means 220 and the second resonance means 230 to the induction heating coil 100 by an input operation by an operator. . Specifically, the operation means includes an operation means having an operation knob that can be input by an operator, for example, and the maximum outputs of the first resonance means 220 and the second resonance means 230 are 100% and 0%. When the operation knob is input within the range of 100% or less, the first resonance means 220 and the second resonance means 230 are controlled to have a current value corresponding to the set value that is input by the constant current control. Set and input each AC power. Then, the control means causes the first resonance means 220 to supply a predetermined high-frequency AC power to the induction heating coil 100 by constant current control so that the current value becomes constant at the set output ratio. Further, the control means causes the second resonance means 230 to supply a predetermined medium-frequency AC power to the induction heating coil 100 with an AC power having an output ratio set similarly by the constant current control. These high-frequency AC power and medium-frequency AC power can be supplied independently, and can be supplied in a state where the high-frequency and medium-frequency are appropriately superimposed.

[Operation of heating device]
(Induction heat treatment)
Next, the operation of the induction heating process will be described as the operation of the heating device 10 in the above-described embodiment. Here, as described above, the operation of heat-treating a metal material having a plurality of projections and depressions on the surface of the object 11 to be heated, such as a gear, a screw, or a bolt, will be described.

  First, the object to be heated 11 is placed in a predetermined heating chamber (not shown) in which the induction heating coil 100 is provided. Then, when the control means outputs the medium frequency AC power converted by the second oscillation means 231 in the second resonance means 230 based on the set value set in advance corresponding to the state of induction heating. The bus bar 234 and the second capacitor C2 enter a series resonance state and are supplied to the induction heating coil 100 by bypassing the first divided winding 212A and the second divided winding 212B of the first transformer 210, and the induction heating coil 100 The object to be heated 11 is induction-heated by 100. When the medium frequency AC power is supplied to the induction heating coil 100, the first capacitor C1 in the first resonance means 220 attenuates the medium frequency feedback, and the first divided winding of the first transformer 210 is attenuated. The induction heating coil 100 is supplied with medium frequency AC power bypassing the wire 212A and the second divided winding 212B. Here, since the first capacitor C1 has a small capacitance due to high frequency matching in the first resonance means 220, the impedance at the medium frequency becomes very large, and the intrusion of the medium frequency component is sufficiently prevented. The

  Further, when the high-frequency AC power converted by the first oscillating means 221 in the first resonance means 220 is output by the control means based on a set value set in advance corresponding to the state of induction heating, The first capacitor C1 enters a series resonance state, is supplied to the induction heating coil 100 through the first transformer 210, and the object to be heated 11 is induction heated by the induction heating coil 100. When high-frequency AC power is supplied to the induction heating coil 100, the conductor L1, which is a bus bar in the bypass circuit 233, attenuates the high-frequency feedback component from the first resonance means 220 in the second resonance means 230. At the same time, the bypass series circuit C3 of the first split capacitor C3A and the second split capacitor C3B compensates for the reactive power of the first transformer 210.

  Here, the attenuation of the high-frequency feedback component in the second resonance means 230 is affected by the high-frequency feedback component because the reactance greatly differs from the impedance corresponding to the reactance of the bypass series circuit C3 that bypasses the high frequency. By setting the second resonance means 230, the damping effect for suppressing the high-frequency feedback current from flowing into the second resonance means 230 is enhanced. That is, by suppressing the high-frequency feedback current to 1/5 to 1/10 or less of the load current flowing in the induction heating coil 100, stable frequency synchronization can be obtained and induction heating control can be performed satisfactorily. For this reason, the ratio of reactance to the impedance of the second capacitor C2 is similarly required to be 5 to 10 times or more. Therefore, for example, as in the circuit shown in FIG. 2, when the reactor L2 having such reactance is connected in series to the second capacitor C2 to attenuate the feedback component, the reactor L2 outputs low-frequency AC power. When doing so, extra reactive power is generated. FIG. 2 is a circuit diagram showing a schematic configuration of a heating device 20 serving as a comparative example for explaining the technology that is a premise of the heating device 10 in the present embodiment, and is equivalent to the heating device 10 shown in FIG. The same reference numerals are given to the configurations.

  That is, in the heating device 20 having the circuit configuration shown in FIG. 2, when the voltage of the first transformer 210 shown in FIG. 3 is compared with the voltage of the third transformer 232 shown in FIG. The voltage of the third transformer 232 is about three times as high, and the reactive voltage on the low frequency side is high. This is because the phase of voltage and current is shown in FIG. 5 due to series resonance by the bypass series circuit C3 and the stray inductance of the bus bar connecting the bypass series circuit C3 to the secondary winding 212 of the first transformer 210. As shown in the figure, since it is delayed by 90 °, a composite voltage is generated and the voltage on the low frequency side is increased. Therefore, in the configuration of the heating device 20 provided with the reactor L2 as shown in FIG. 2, the specification of the kilovolt ampere (kVA specification) in the second capacitor C2 is also increased in order to compensate for the reactive power generated excessively by the reactor L2. It is necessary to increase the cost. In addition, since a certain amount of reactance is required, a resistance loss in the reactor L2, for example, a resistance loss of about 5% occurs in the same specification as the heating device 10.

  On the other hand, the bypass series circuit C3 and the conductor L1 in the heating device 10 constitute a series resonance circuit using high frequency, and the impedance Z in the bypass circuit 233 is obtained by the following equation (4). The inductance of the conductor L1 is set so that the resonance frequency f of the bypass circuit 233 is the same as the high frequency. Note that the resonance frequency f of the bypass circuit 233 is obtained by the following equation (5).

(Equation 4)
Z = r + jωL + (1 / j) ωC
r: resistance value of bus bar or conductor L1 [Ω]
j: Coefficient

(Equation 5)
f = (1/2) π (L × C) ^1/2

  Therefore, the impedance Z of the bypass circuit 233 at a high frequency is the same as the resistance value r of the bus bar or the conductor L1 (Z = r). And since this resistance value r is a bus bar or the conductor L1, it will be far less than the reactance X of the bypass series circuit C3. For example, in the heating apparatus 10 having the specification for induction heating at the above-described frequency, the first divided capacitor C3A and the second divided capacitor C3B are about tens of μF, so that it is about 1/50 or less. The reactance X of the bypass series circuit C3 is obtained by the following equation 6.

(Equation 6)
X = (1 / ω) C

  Further, since the first divided capacitor C3A and the second divided capacitor C3B constituting the bypass series circuit C3 are grounded, the voltage drop at both ends of the bypass circuit 233 is extremely different from the configuration in which the bypass is made by one capacitor. Get smaller. Therefore, the high-frequency feedback voltage related to the secondary winding 212 of the first transformer 210 is correspondingly reduced. As a result, the inductance set to prevent the high-frequency feedback current from entering may be a very small value. That is, by setting the impedance Z of the bypass circuit 233 that bypasses the high frequency component, the set inductance is also reduced. Further, since the inter-plate gap G in the conductor L1 is appropriately set and set to a predetermined value as the inductance setting, the combined voltage becomes small. For this reason, the power factor of the second inverter 231B approaches 1, and low-frequency AC power can be efficiently supplied.

  Therefore, in the heating apparatus 10 having the above-described specification, the bypass series circuit C3 that bypasses the high-frequency component is connected to the secondary winding 212 of the first transformer 210 with the conductor L1 set to a predetermined inductance that is a bus bar. With a simple configuration for constructing the bypass circuit 233, only the stray inductance of the bus bar 234 up to the first inverter 231B in the second resonance means 230 is sufficiently blocked, and the heating device 20 as shown in FIG. As in the configuration, it is not necessary to provide the reactor L2. For this reason, high frequency interference can be prevented without providing the reactor L2, the frequency synchronization control in the second oscillating means 231 is stabilized with a simple configuration, and the occurrence of resistance loss due to the reactor L2 is also prevented. The efficiency of matching is improved and efficient induction heating can be performed with a low frequency. Furthermore, heat generation due to the resistance loss of the reactor L2 does not occur, and good induction heating can be performed.

[Effect of heating device]
As described above, in the above-described embodiment, the primary winding of the first transformer 210 in which the supplied DC power is converted into AC power having a predetermined high frequency and the secondary winding 212 is connected to the induction heating coil 100. A first capacitor C1 that constitutes a series resonance circuit is provided between the voltage-type first inverter 221B that outputs to the line 211 and the primary winding 211 of the first transformer 210 to provide a first resonance. The frequency component fed back from the 2nd resonance means 230 which comprises the means 220, and supplies the alternating current power of medium frequency different from the high frequency converted with the 1st inverter 221B with the 1st capacitor | condenser C1 is attenuated, and 1st The reactive power of the transformer 210 and the induction heating coil 100 is compensated, and predetermined high frequency AC power is supplied from the first resonance means 220 to the induction heating coil 100 to cause induction heating. Also, the output side of the voltage-type second inverter 231B that converts the supplied DC power into AC power of medium frequency different from that of the first resonance means 220 and outputs it to the secondary winding 212 of the first transformer 210. Is provided with a second capacitor C2 constituting a series resonance circuit, and the reactive power of the first transformer 210 and the induction heating coil 100 is compensated by the second capacitor C2. A high frequency AC power is supplied to the induction heating coil 100 to cause induction heating. A bypass series circuit C3 that bypasses the high-frequency component from the first inverter 221B in the first resonance means 220 is connected to the secondary winding 212 of the first transformer 210, and series resonance with the bypass series circuit C3. The conductor L1 constituting the circuit is connected in series to the bypass series circuit C3, and the high frequency component fed back from the first resonance means 220 is attenuated by the series resonance circuit.

  For this reason, the series circuit of the conductor L1 and the bypass series circuit C3 constituting the series resonance circuit has an inductance L of the conductor L1 in a state where the resonance frequency corresponds to the high frequency of the AC power supplied from the first resonance means 220. Therefore, the impedance Z of the conductor L1, the bypass series circuit C3, and the series circuit approximates the resistance value r of the conductor L1, which is greatly reduced with respect to the reactance X of the bypass series circuit. Then, by providing a reactor whose reactance is significantly lower than the impedance that becomes the reactance of the bypass series circuit C3, the feedback current is largely suppressed with respect to the load current flowing through the induction heating coil 100, and therefore the conductor L1 having a small reactance. Therefore, the configuration is simplified, the load of the reactance component connected in series with the second capacitor C2 to attenuate the feedback is reduced, and the reactor can be omitted as the reactance component, so that the second capacitor C2 can be omitted. In addition, it is possible to suppress the generation of resistance loss due to the reactor L2 that is prevented from being fed back by a series resonance circuit that is connected in series to each other and to prevent the possibility of heat generation. Therefore, for example, in a voltage form in which commercial AC power is converted to DC power and then converted to AC power of a predetermined frequency, the object to be heated 11 is heated by induction heating, and the permeability is changed. When the load fluctuates due to changes in the shape, material, quenching state, etc. of the heated object 11, good induction heating control using a voltage-type inverter with good load applicability, which corresponds to the fluctuation As a result, the frequency synchronization control of the AC power supplied from the second resonance means 230 due to the reduction of the mutual interference is stabilized, and efficient induction heating with reduced resistance loss can be easily performed with a simple configuration.

  Then, the first divided winding 212A and the second divided winding 212B obtained by dividing the secondary winding 212 of the first transformer 210 are connected in series to form a series circuit of the bypass series circuit C3 and the conductor L1. A connection point between the first divided winding 212A and the second divided winding 212B is connected in series to the first divided winding 212A and the second divided winding 212B. For this reason, for example, the position of the connection point between the first divided winding 212A and the second divided winding 212B, that is, grounding by the bypass circuit 233, the ground potential is reduced corresponding to the division ratio. The split winding 212A and the second split winding 212B are halved, and the first transformer 210 can be prevented from being damaged by discharge. Further, it is possible to easily set a voltage drop in the series circuit of the bypass series circuit C3 and the conductor L1, and the feedback voltage from the first resonance means 230 is reduced according to the reduction of the voltage drop. In order to reduce the load of the reactor L2 that needs to be connected in series to the second capacitor C2 to reduce the load of the reactor L2, and to compensate the reactive power according to the reactance for blocking the feedback voltage The kVA specification of the second capacitor C2 is also reduced. For this reason, it is possible to prevent feedback by stray inductance in the bus bar 234 for supplying AC power from the second resonance means 230, simplifying the configuration by omitting the reactor L2, suppressing the occurrence of resistance loss, and generating heat in the reactor L2. Can be prevented and induction heating can be performed efficiently.

  Further, the primary winding 232A is connected in series with the second capacitor C2 on the output side of the second inverter 231B, and the secondary winding 232B is connected to the first split winding 212A and the first winding of the first transformer 210. A third transformer 232 connected in parallel to the series circuit of the bypass series circuit C3 and the conductor L1 in series at the connection point of the two-divided winding 212B is provided in the second resonance means 230, and the third transformer The impedance of the AC power output from the second inverter 231B is converted to a predetermined value by the device 232. For this reason, the AC power from the first resonance means 220 and the AC power from the second resonance means 230 are well matched, and it is easy to supply in synchronization with a state where different frequencies are superimposed, Better induction heating is easily obtained.

  Further, the first divided capacitor C3A and the second divided capacitor C3B are connected in series to form a bypass series circuit C3, and a connection point between the first divided capacitor C3A and the second divided capacitor C3B, which are the connection points of the series connection. Is grounded. For this reason, the voltage drop at both ends in the series circuit of the bypass series circuit C3 and the conductor L1 becomes extremely small, the feedback voltage of the high frequency component from the first resonance means 220 is reduced, and the second in order to reduce the feedback. It is possible to greatly reduce the load of the reactor L2, that is, the reactor component, which needs to be connected in series to the capacitor C2 of the reactor, that is, the reactor component, and the stray inductance in the bus bar 234 for supplying AC power from the second resonance means 230 The feedback of the high-frequency component from the first resonance means 220 can be sufficiently prevented, the configuration can be simplified by omitting the reactor L2, the occurrence of resistance loss can be suppressed, the possibility of heat generation in the reactor L2, and the induction heating can be efficiently performed. it can.

  Also, a conductor that is a bus bar that connects the bypass series circuit C3 to the secondary winding 212 of the first transformer 210, and the AC power supplied by the first resonance means 220 by the bypass series circuit C3. The conductor L1 set to an inductance having a series resonance frequency corresponding to a high frequency prevents feedback of high frequency components. For this reason, the conductor L1 that serves as a bus bar for connecting and bypassing the bypass series circuit C3 for bypassing the high-frequency component from the first resonance means 220 functions as a reactor that prevents the feedback of the high-frequency component. Thus, an inductance whose reactance is significantly lower than the impedance of the bypass series circuit C3 is set, the feedback current is greatly suppressed with respect to the load current flowing through the induction heating coil 100, and the high frequency from the first resonance means 220 is satisfactorily improved. The feedback of the component can be prevented, and the load of the reactor L2, which is required to be connected in series with the second capacitor C2 in order to reduce the feedback, that is, the reactor component can be greatly reduced, and the AC power is supplied from the second resonance means 230. For the stray inductance in the bus bar 234 for the first resonance hand The return of the high-frequency components from 220 can be sufficiently prevented, simplified construction by omitting the reactors L2, suppression of the resistance loss occurs, can be easily prevented fear of heat generation in the reactor L2, it can be efficiently induction heated.

  And as a conductor L1, a pair of 1st electroconductive board respectively connected in series with respect to the bypass series circuit C3 through the inter-plate gap G which is the flat shape of the same shape and a plane is a predetermined gap | interval. L1A and the second conductive plate L1B are provided. For this reason, simplification of the configuration, suppression of occurrence of resistance loss, and prevention of heat generation in the reactor can be easily achieved with a simple configuration, and induction heating can be performed efficiently.

  Further, a pair of first conductive plates L1A and a second conductive plate L1A with a gap G between the plates set to an inductance having a series resonance frequency corresponding to a high frequency of the AC power supplied by the first resonance means 220 by the bypass series circuit C3. With the simple configuration in which the conductive plates L1B are arranged to face each other, simplification of the configuration, suppression of the occurrence of resistance loss, and prevention of heat generation in the reactor can be easily performed, and induction heating can be performed efficiently.

  Further, the second resonance means 230 supplies medium frequency AC power lower than the high frequency of the AC power supplied by the first resonance means 220. For this reason, it is sufficient to set a reactance that is significantly lower than the impedance of the bypass series circuit C3 that bypasses the high-frequency component as a feedback prevention of the high-frequency component. Therefore, the bypass circuit 233 is not provided with a special reactor. The feedback of the high frequency component is suppressed by effectively utilizing the stray inductance due to the bus bar which is the circuit line of the circuit. Therefore, the structure that simplifies the structure, suppresses the occurrence of resistance loss, and prevents the heat generation in the reactor effectively functions by the conductor L1 serving as a bus bar, and the induction heating can be efficiently performed with the simple structure.

  Then, the first inverter 221B converts it to high frequency AC power of 50 kHz or more and 1 MHz or less, and the second inverter 231B converts it to medium frequency AC power of 1 kHz or more and 50 kHz or less, and supplies it to the induction heating coil 100. Since the metal material such as gears, screws, and bolts having irregularities on the surface as the object to be heated 11 is induction-heated, the surface of the metal material is well quenched by the AC power from the first resonance means 220, and the metal material The inside is well quenched with AC power from the second resonance means 230, the metal material is well contoured and good heat treatment can be performed.

  Further, voltage-type first inverter 221B and second inverter 231B are used for the first resonance means 220 and the second resonance means 230, respectively. The first converter 221A and the second converter that convert the AC power into DC power and output the DC power as the DC power that is converted from the voltage-type first inverter 221B and the second inverter 231B to the AC power of a predetermined frequency, respectively. By adopting a configuration in which power is supplied from 231A, the configuration of forward conversion for supplying DC power to the first resonance means 220 and the second resonance means 230 is shared, for example, the first converter in the heating apparatus 10 shown in FIG. 221A and the second converter 231A are shared, and the first converter 221A and the second converter 231A are shared as in the heating device 30 shown in FIG. 6, and the first smoothing capacitor Cf1 and the second converter 231A are shared. Smoothing capacitor Cf2 can be shared, further simplification of the structure can be obtained, and productivity can be improved. Capital reduction of easily achieved. In FIG. 6, the same components as those of the heating device 10 shown in FIG.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and various modifications such as modifications and improvements within the scope of achieving the object of the present invention without departing from the gist of the present invention are included in the present invention. It is.

  For example, the reactor L2 may be provided in series with the second capacitor C2 when the high frequency feedback prevention cannot be sufficiently obtained by the conductor L1 of the bypass circuit 233 due to the induction heating specification. By this reactor L2, the feedback of a high frequency component can be prevented more and the stable favorable induction heating can be performed. In addition, as the reactor L2 separately provided in the above-described heating devices 10 and 30, since the feedback of the high-frequency component is largely suppressed by the conductor L1, the inductance is higher than that of the heating device 20 shown in FIG. A small specification may be used, and the configuration can be simplified even if the reactor L2 is provided.

  Further, the configuration in which high-frequency AC power is supplied as the first resonance unit 220 and medium-frequency AC power is supplied as the second resonance unit 230 has been described. Any configuration that supplies power may be used. Further, the AC power may be supplied not only in the above-described range but also in other frequency bands as the high frequency and medium frequency. In addition, although the heating device 10 is configured by a pair of configurations of the first resonance unit 220 and the second resonance unit 230 that supply AC power at different frequencies, as described above, AC power of another frequency is further generated. A configuration including a resonance means to supply may be used.

  Further, as the first resonance means 220 and the second resonance means 230, the configurations of the first converter 221A and the second converter 231A, the first smoothing capacitor Cf1 and the second smoothing capacitor Cf2 are used in the induction heating apparatus 200. It is good also as a structure connected with respect to another. It should be noted that not only the bridge rectifier circuit described above for forward conversion but also various circuit configurations such as a half bridge type as well as a full bridge type can be used as a reverse conversion configuration.

  And as above-mentioned as the to-be-heated object 11, what was induction-heated, such as a composite material in which a steel pipe, a complicated-shaped gear having a plurality of irregularities on the surface, and a plurality of members are laminated, is used. Can be targeted. Moreover, although the structure which supplies a high frequency and a medium frequency was demonstrated, it is good also as a structure which supplies another frequency. Furthermore, not only the high frequency and the medium frequency but also any configuration that can supply at least two different frequencies in a superimposed manner can be adopted.

  Moreover, although the structure which controls both the 1st oscillating means 221 and the 2nd oscillating means 231 was illustrated as a control means, for example, you may divide and control to the structure controlled independently, respectively. Furthermore, it is good also as an independent structure not only the structure which contains a control means in the induction heating apparatus 200. FIG.

  Further, as a reactor configuration for preventing feedback from the first resonance means 220 in the bypass circuit 233, a conductor in which a pair of first conductive plate L1A and second conductive plate L1B are arranged to face each other with a predetermined gap G between the plates. Not only L1, but any reactor such as various resistors can be used. And if the structure which provides a reactor can be satisfactorily prevented from returning, it is not limited to a structure using a pair of opposing conductive plates, but any bus bar structure, such as a conductive wire wired with a predetermined gap, and any shape of conductive A configuration using members can be applied.

  The bypass series circuit C3 is not limited to the configuration in which the two first divided capacitors C3A and the second divided capacitor C3B are connected in series, and may be a series circuit divided into three or more. Furthermore, it is not limited to the case where the first divided capacitor C3A and the second divided capacitor C3B having the same specifications are divided into two, but may be a series circuit divided in a state where the capacitances are different. Similarly, the secondary winding 212 of the first transformer 210 is not limited to being divided into two parts, but may be divided into a plurality of parts, and the dividing ratio may be different.

  In addition, the specific structure and procedure for carrying out the present invention may be changed to other configurations as long as the object of the present invention can be achieved.

It is a circuit diagram which shows schematic structure of the heating apparatus which concerns on one embodiment of this invention. It is a circuit diagram which shows schematic structure of the heating apparatus used as the comparative example for demonstrating the technique used as the premise of the heating apparatus in the said one Embodiment. It is a wave form diagram which shows the voltage of the 1st transformer in the heating apparatus shown in the said FIG. It is a wave form diagram which shows the voltage of the 2nd transformer in the heating apparatus shown in the said FIG. It is a wave form diagram which shows the relationship between the voltage in the heating apparatus shown in the said FIG. 2, an electric current, and a synthetic voltage. It is a circuit diagram which shows schematic structure of the heating apparatus which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Heating device 11 ... Object to be heated 100 ... Induction heating coil 200 ... Induction heating device 210 ... First transformer 211 as a transformer 211 ... Primary winding 212 ... Secondary winding 212A First split winding 212B as split winding Second split winding 220 as split winding 220 First resonance means 221A First converter 221B forward conversion means First reverse conversion means First inverter 230 as ... Second resonance means 231A ... Second converter 231B as forward conversion means ... Second inverter as second reverse conversion means 233 ... Bypass circuit C1 ... First Capacitor C2 ... Second capacitor C3 ... Bypass series circuit as a bypass capacitor C3A ... First division capacitor as a division capacitor C3B ... Division capacitor Second divided capacitor L1 ...... second conductive plate as the first conductive plate L1B ... conductive plate as a conductor L1A ... conductive plate as reactor and

Claims (16)

An induction heating device that supplies electric power of two different frequencies to an induction heating coil to inductively heat an object to be heated,
A transformer having a secondary winding connected to the induction heating coil;
First resonance means for supplying AC power of a predetermined frequency to the induction heating coil through the transformer;
Second resonance means for supplying AC power of a frequency different from the frequency of the first resonance means to the induction heating coil,
The first resonance means converts the supplied DC power into AC power having a predetermined frequency and outputs it to the primary winding of the transformer. A series resonance circuit is provided between the inverse conversion means and the primary winding of the transformer to compensate for the reactive power of the transformer and the induction heating coil and to attenuate the frequency component fed back from the second resonance means A first capacitor to be
The second resonance means converts the supplied DC power into AC power having a frequency lower than the frequency converted by the first inverse conversion means, and outputs the AC power to the secondary winding of the transformer. 2 reverse conversion means, a second capacitor which is provided on the output side of the second reverse conversion means and constitutes a series resonance circuit to compensate for reactive power of the transformer and the induction heating coil, and the transformer A bypass capacitor that is connected to the secondary winding of the first bypass converter and bypasses the frequency component from the first inverse converter, and is connected in series to the bypass capacitor to form a series resonant circuit. An induction heating apparatus comprising: a reactor that attenuates a frequency component fed back from the first resonance means. The induction heating device according to claim 1,
The secondary winding of the transformer has a plurality of split windings connected in series,
The induction heating apparatus, wherein the second resonance means is configured such that a series resonance circuit of the bypass capacitor and the reactor is connected in series with the divided winding at a connection point of the divided winding. The induction heating device according to claim 2,
In the second resonance means, the primary winding is connected in series with the second capacitor on the output side of the second inverse conversion means, and the secondary winding is the secondary winding of the transformer. Connected in parallel to a series resonance circuit of the bypass capacitor and the reactor connected in series to the split winding at a connection point of the split winding in a line, and output from the second inverse conversion means An induction heating device comprising a transformer for converting the impedance of alternating current power into a predetermined value. An induction heating apparatus according to any one of claims 1 to 3,
The bypass capacitor includes a plurality of divided capacitors connected in series and grounded at a connection point of each other. An induction heating apparatus according to any one of claims 1 to 4,
The reactor is a conductor that connects the bypass capacitor to the secondary winding of the transformer, and is set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the bypass capacitor by the first resonance means. An induction heating device characterized by that. The induction heating device according to claim 5,
The induction heating apparatus according to claim 1, wherein the conductor includes a pair of conductive plates having a plate shape of the same shape and a plane opposed to each other with a predetermined gap and connected in series to the bypass capacitor. The induction heating device according to claim 6,
The pair of conductive plates are arranged to face each other with a gap set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means by the bypass capacitor. apparatus. An induction heating device that supplies electric power of two different frequencies to an induction heating coil to inductively heat an object to be heated,
A transformer in which a secondary winding in which a plurality of split windings are connected in series is connected to the induction heating coil;
First resonance means for supplying AC power of a predetermined frequency to the induction heating coil through the transformer;
Second resonance means for supplying AC power of a frequency different from the frequency of the first resonance means to the induction heating coil,
The first resonance means converts the supplied DC power into AC power having a predetermined frequency and outputs it to the primary winding of the transformer. A series resonance circuit is provided between the inverse conversion means and the primary winding of the transformer to compensate for the reactive power of the transformer and the induction heating coil and to attenuate the frequency component fed back from the second resonance means A first capacitor to be
The second resonance means converts the supplied DC power into AC power having a frequency lower than the frequency converted by the first inverse conversion means, and between the split windings in the secondary winding of the transformer. A second reverse conversion means of voltage type to output, and a second resonance converter provided on the output side of the second reverse conversion means to constitute a series resonance circuit and compensate for the reactive power of the transformer and the induction heating coil A capacitor and a series circuit of a plurality of divided capacitors connected in series with the divided windings between the divided windings and connected in series and grounded at the connection point to each other; from the first resonance means An induction heating apparatus comprising: a bypass circuit that suppresses feedback of the frequency of the first frequency and bypasses the frequency component from the first inverse conversion means. The induction heating device according to claim 8,
The induction heating device, wherein the bypass circuit is set to an inductance having a series resonance frequency corresponding to the frequency of the AC power supplied by the first resonance means. The induction heating apparatus according to claim 8 or 9, wherein
The bypass circuit includes a first conductive plate connected between one end of the series circuit of the split capacitor and one end of one split winding in the secondary winding of the transformer, and the series circuit of the split capacitor A second conductive plate connected between the other end of the transformer and one end of the other split winding in the secondary winding of the transformer, and arranged in parallel via a predetermined gap. Induction heating device. The induction heating device according to claim 10,
The bypass circuit includes the first conductive plate and the second conductive plate with a gap set to an inductance having a series resonance frequency with respect to the frequency of the AC power supplied by the first resonance means by the series circuit of the divided capacitors. An induction heating device characterized in that the conductive plates are arranged to face each other. The induction heating device according to any one of claims 1 to 11,
The induction heating apparatus, wherein the second resonance means supplies AC power having a frequency lower than the frequency of AC power supplied by the first resonance means. An induction heating apparatus according to any one of claims 1 to 12,
Comprising forward conversion means for converting alternating current power into the direct current power and outputting it,
The induction heating apparatus, wherein the first reverse conversion unit and the second reverse conversion unit respectively convert the DC power output from the forward conversion unit into AC power having a predetermined frequency. An induction heating coil for induction heating the object to be heated;
The induction heating device according to any one of claims 1 to 13, wherein the induction heating coil is induction-heated by supplying electric power of two different frequencies to the induction heating coil.
A heating apparatus comprising: The heating device according to claim 14,
In the induction heating device, the frequency converted by the first reverse conversion means is 50 kHz or more and 1 MHz or less, and the frequency supplied by the second reverse conversion means is 1 kHz or more and 50 kHz or less,
The induction heating coil induction-heats a metal material having irregularities on the surface as the object to be heated. The induction heating apparatus according to any one of claims 1 to 13, wherein an AC power having a predetermined frequency output from the first resonance unit and the first power output from the second resonance unit are used. An induction heating method characterized by inductively heating an object to be heated by superimposing or switching alternating current power of a frequency different from the frequency of the resonance means to supply to an induction heating coil.

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