JP4652983B2 - Induction heating device - Google Patents

Description

  The present invention relates to an inverter type electromagnetic induction heating apparatus that performs induction heating by supplying desired power to an object to be heated of different materials.

  In recent years, an inverter type electromagnetic induction heating apparatus that heats an object to be heated such as a pot without using a fire has been widely used. The electromagnetic induction heating device applies a high-frequency current to the heating coil, generates an eddy current in a heated object made of a material such as iron or stainless steel, which is disposed in the vicinity of the coil, and the electric resistance of the heated object itself. Causes fever. It is recognized as a new heat source because it can control the temperature of the object to be heated and is highly safe. Conventionally, electric cookers incorporated in system kitchens and the like have used resistors such as sheathed heaters, plate heaters, and halogen heaters as heat sources, but in recent years, some of them have been replaced with induction heating cookers. It is being replaced by one that has been used as an induction heating cooker.

  As a known example 1 of such an electromagnetic induction heating device, there is an induction heating device as disclosed in JP-A-6-140135. In this known example, high frequency output of a full bridge inverter is applied to a load circuit having a work coil for induction heating via a high frequency transformer to perform induction heating. The load circuit has a configuration in which a choke coil is connected in series to a parallel resonance circuit in which a resonance capacitor is connected in parallel to an induction heating work coil. Since the load circuit is a parallel resonance circuit, the impedance of the load circuit viewed from the input side is maximum in the resonance state, and therefore no large current flows through the choke coil. On the other hand, since a large current flows through the work coil and the resonant capacitor of the load circuit, induction heating can be performed efficiently.

  Further, as known example 2, there is an induction heating device as disclosed in JP-A-2004-348993. In this known example, a series resonant circuit composed of a reactor L, a capacitor C1, and a heating coil and a parallel resonant circuit composed of an equivalent capacitor of the capacitor C1 and capacitor C2 and a heating coil are connected to the output terminal of the inverter. It resonates at the fundamental frequency, and the parallel resonance resonates at the nth harmonic of the fundamental frequency. This allows induction heating at different frequencies.

JP-A-6-140135 JP 2004-348993 A

  In the known example 1 and the known example 2, since a high-frequency transformer and a high-frequency inductor are necessary, the core material and the wire are required to be a high-frequency type, and there are problems such as an increase in cost and an increase in circuit size.

  An object of the present invention is to address the above-described problems and to provide an induction heating apparatus having a small and inexpensive circuit without using a high-frequency transformer or a high-frequency inductor.

  The present invention includes a resonant load circuit including an object to be heated and an inverter that converts a DC voltage into an AC voltage and supplies power to the resonant load circuit, and the inverter is connected in series with at least two switching units. In an induction heating apparatus having upper and lower arms composed of elements, wherein the upper and lower arms have at least one pair of upper and lower arms, the resonance load circuit includes at least two, and the resonance frequency of one resonance load circuit Is superimposed on the current flowing at the resonance frequency of the other resonant load circuit.

  According to the present invention, since a high-frequency transformer or a high-frequency inductor is not used, an inexpensive induction heating device with a small circuit can be provided.

Example 1
FIG. 1 is a circuit configuration diagram of an induction heating apparatus according to the first embodiment of the present invention.

  The first embodiment of the present invention will be described below with reference to FIG.

  In FIG. 1, assuming that the positive electrode side of the smoothing capacitor 113 is p point and the negative electrode side is o point, the upper and lower arms in which IGBT 103 and IGBT 104 which are power semiconductor switching elements are connected in series between the p point and the q point. 10 is connected.

  Diodes 105 and 106 are respectively connected in parallel to the IGBTs 103 and 104 in the reverse direction, and snubber capacitors 107 and 108 are connected to each IGBT. Snubber capacitors 107 and 108 are charged or discharged by a cut-off current when IGBT 103 and IGBT 104 are turned off.

  Since the capacitances of the snubber capacitors 107 and 108 are sufficiently larger than the output capacitance between the collectors and emitters of the IGBTs 103 and 104, the change in the voltage applied to both IGBTs at the time of turn-off is reduced, and the turn-off loss is suppressed.

  If the connection point of the IGBTs 103 and 104, that is, the output terminal of the upper and lower arms 10 is a point d, the heating coil 109 and a DC cut capacitor 110 (DC suppression capacitor) are connected between the points d and c. A resonant capacitor 111 and a resonant reactor 112 are connected between the q points.

  In FIG. 1, in this embodiment, a harmonic current having a resonance frequency determined by the resonance reactor 112 and the resonance capacitor 111 is superimposed on a fundamental wave current having a resonance frequency determined by the heating coil 109 and the resonance capacitor 111.

  The resonant load circuit through which the fundamental current and the harmonic current flow includes a first resonant load circuit configured by the heating coil 109 and the resonant capacitor 111, and a second resonant load configured by the resonant reactor 112 and the resonant capacitor 111. Having at least two or more resonant load circuits, including circuits. The resonant load circuit generally includes an object to be heated.

  FIG. 2 shows the frequency characteristics of the equivalent resistance in the material of the object to be heated, and FIG. 3 shows the frequency characteristics of the equivalent inductance.

  The equivalent inductance is shown in FIG. 2 for a magnetic object such as iron as shown in (1), a nonmagnetic stainless steel as shown in (2), and a nonmagnetic object such as copper or aluminum as shown in (3). The heated product is about ½ smaller.

  On the other hand, the equivalent resistance is about 10 to 20 times larger in the magnetic heated object as in (1) and the non-magnetic heated object as in (3). Further, it shows a characteristic that the equivalent resistance increases due to the skin effect when the frequency is increased regardless of the material.

  That is, when heating a nonmagnetic object to be heated such as aluminum, it is desirable to heat at a frequency as high as possible.

  Therefore, by superimposing higher-order harmonics on the fundamental frequency, it becomes possible to heat with the fundamental and harmonic components, thereby improving efficiency. Furthermore, noise can be reduced by dispersing the spectrum of radiation noise.

  Next, the operation mode will be described with reference to the timing chart shown in FIG.

  Here, the voltage at the point d in FIG. 1 is Vd, the current flowing through the IGBT 103 and the diode 105 is Ic103, and the current flowing through the IGBT 104 and the diode 106 is Ic104. The current flowing through the resonant reactor 112 is IL112, the resonant current flowing through the heating coil 109 is IL109, and the direction from point d to point c in FIG. 1 is defined as positive.

  The IGBT 103 and the IGBT 104 operate in a complementary manner, and the drive frequency is driven at a frequency higher than the resonance frequency determined by the heating coil 109 and the resonance capacitor 111.

  Note that the drive frequency at which the IGBT 103 and the IGBT 104 as the switching elements are turned on / off is lower than the harmonic resonance frequency determined by the resonance reactor 112 and the resonance capacitor 111. For this reason, the drive frequency (switch operation timing) of the IGBT 103 and the IGBT 104 matches the resonance frequency (fundamental wave) determined by the heating coil 109 and the resonance capacitor 111.

(Mode 1)
When the IGBT 103 is turned on and the stored energy of the heating coil 109 becomes zero, the polarity of the resonance current IL 109 changes from negative to positive, and the resonance current passes from the smoothing capacitor 113 to the IGBT 103, the heating coil 109, the DC cut capacitor 110, and the resonance capacitor 111. IL 109 flows, and a resonance current IL 112 flows through the path of the resonance capacitor 111 and the resonance reactor 112.

(Mode 2)
Next, when the IGBT 103 is turned off, the resonance current IL109 has a positive polarity. This current charges the upper arm snubber capacitor 107, discharges the lower arm snubber capacitor 108, and the voltage Vd at the point d gradually increases. descend.

  Thereafter, when a forward voltage is applied to the diode 105, the resonance current IL 109 flows as a recirculation current through the heating coil 109, the DC cut capacitor 110, the resonance capacitor 111, and the diode 106, and the resonance capacitor 111 and the resonance reactor 112. The resonance current IL112 continues to flow through the path.

(Mode 3)
Next, when the IGBT 104 is turned on and the accumulated energy of the heating coil 109 becomes zero, the polarity of the resonance current IL109 changes from positive to negative, and the resonance current IL109 passes through the path of the resonance capacitor 111, the DC cut capacitor 110, the heating coil 109, and the IGBT 104. The resonance current IL112 is inverted and flows through the path of the resonance capacitor 111 and the resonance reactor 112.

  At this time, since the IGBT 104 keeps the gate voltage on during the period in which the current flows through the diode 106, ZCS and ZVS turn-on without switching loss are realized.

(Mode 4)
Next, when the IGBT 104 is turned off, the resonance current IL109 has a negative polarity. This current charges the lower arm snubber capacitor 108, discharges the upper arm snubber capacitor 107, and the voltage Vd at the point d gradually increases. To rise.

  Thereafter, when a forward voltage is applied to the diode 105, the resonance current IL109 flows as a circulating current through the heating coil 109, the diode 105, the smoothing capacitor 113, the resonance capacitor 111, and the DC cut capacitor 110, and the resonance current IL112 is It continues to flow in the path of the resonant capacitor 111 and the resonant reactor 112.

  As described above, by repeating the above operation, the smoothing capacitor 113 is used as a power source through the power supply circuit 101, the rectifying circuit 102, and the smoothing choke 114, and the high frequency current having the resonance frequency determined by the resonance capacitor 111 and the resonance reactor 112 is heated. A high-frequency current having a resonance frequency determined by the coil 109 and the resonance capacitor 111 is superimposed, and two types of high-frequency currents can be supplied to the heating coil. The object to be heated is induction-heated by the magnetic flux generated from the heating coil 111.

  The power supplied to the object to be heated can be adjusted by controlling the driving frequency of the upper and lower arms 10.

  As in this embodiment, the current flowing in the resonance circuit becomes a sine wave due to the inductance of the heating coil and the resonance capacitor, and the resonance current is delayed in phase from the voltage at point d, that is, the output voltage of the inverter.

  Therefore, when the IGBT is turned on, switching is performed in a state where the voltage between the collector and the emitter is zero volts (hereinafter referred to as ZVS), so that no turn-on loss occurs.

  However, when the power supplied to the object to be heated is reduced, the cut-off current of the upper and lower arms 10 is reduced, and the IGBT 103 or 104 is turned on before charging / discharging of the snubber capacitors 105 and 106 is completed, so that ZVS is not satisfied. A condition occurs.

  In such a case, since turn-on loss occurs, for example, as shown in FIG. 5, an IGBT 501 is connected in series with the snubber capacitor 108 of the lower arm, and a diode 502 is connected in antiparallel to the IGBT 501 to connect the IGBT 501. It is desirable to disconnect the snubber capacitor 108 from the upper and lower arms 10 by turning it off.

  Thereby, ZVS can always be realized, and even when the cutoff current is small, the turn-on loss can be eliminated.

  Further, by configuring the full bridge inverter shown in FIG. 6, a voltage twice as large as the half bridge is applied to the heating coil, so that the number of turns of the heating coil can be increased, and high efficiency can be achieved.

(Example 2)
FIG. 7 is a circuit configuration diagram of an electromagnetic induction heating device according to the second embodiment of the present invention.

  A feature of this circuit configuration is that the resonance reactor 112 in FIG. 1 is replaced with a heating coil 701.

  By using the resonant reactor as a heating coil in this way, the amount of magnetic flux that links the pans increases, and the eddy current flowing through the pans increases, that is, the eddy current loss of the pans increases. It becomes possible to do.

The current flowing through the heating coil 109 at this time is a current in which harmonics are superimposed on the fundamental wave, as in the first embodiment, while the harmonic current flows through the heating coil 701.

  Further, by configuring the full bridge inverter shown in FIG. 8, a voltage twice that of the half bridge is applied to the heating coil, so that the number of turns of the heating coil can be increased, and high efficiency can be achieved.

(Example 3)
FIG. 9 is a circuit configuration diagram of an induction heating apparatus according to the third embodiment of the present invention.

  9 differs from FIG. 1 in that a phase advance reactor 901 is connected between one end of the smoothing capacitor 113 and the point p.

  The operation will be described with reference to the time chart of FIG.

  Next, the operation mode will be described with reference to the timing chart shown in FIG. Here, the voltage at the point d in FIG. 9 is Vd, the current flowing through the IGBT 103 and the diode 105 is Ic103, and the current flowing through the IGBT 104 and the diode 106 is Ic104. The resonance current flowing through the resonance reactor 112 is IL102, the resonance current flowing through the heating coil 109 is IL109, and the direction from point d to point c in FIG. 1 is defined as positive.

  The IGBT 103 and the IGBT 104 operate in a complementary manner, and the drive frequency is driven at a frequency lower than the resonance frequency determined by the heating coil 109 and the resonance capacitor 111.

  Note that the drive frequency at which the IGBT 103 and the IGBT 104 as the switching elements are turned on / off is lower than the harmonic resonance frequency determined by the resonance reactor 112 and the resonance capacitor 111. For this reason, the drive frequency (switch operation timing) of the IGBT 103 and the IGBT 104 matches the resonance frequency (fundamental wave) determined by the heating coil 109 and the resonance capacitor 111.

(Mode 1)
When the IGBT 103 is turned on, the current flowing through the IGBT 103 with a slow di / dt is increased by the phase advance reactor 901 to realize ZCS turn-on, and the IGBT 103, the heating coil 109, the DC cut capacitor 110, the resonance capacitor 111, the smoothing capacitor 113, A current flows through the path of the phase advance reactor 901.

  In addition, a current flows through the path of the resonant capacitor 111 and the resonant reactor 112 due to parallel resonance.

(Mode 2)
Next, the current flowing through the heating coil 109 is reversed by resonance, and the current flows through the diode 105 connected in antiparallel with the IGBT 103. ZVS and ZCS turn-off is realized by turning off the IGBT 103 during a period in which a current flows through the diode 105.

  At this time, the resonance current IL109 flows through the path of the heating coil 109, the diode 105, the phase advance reactor 901, the smoothing capacitor 113, the resonance capacitor 111, the DC cut capacitor 110, and the path of the resonance capacitor 111 and the resonance reactor 112.

(Mode 3)
When the IGBT 105 is turned on, the current flowing through the IGBT 105 with a slow di / dt is increased by the phase-advanced reactor 901, realizing ZCS turn-on. IL109 flows.

  In addition, the resonance current IL112 also flows through the path of the resonance capacitor 111 and the resonance reactor 112 due to parallel resonance.

(Mode 4)
Next, the current flowing through the heating coil 109 is reversed by resonance, and the current flows through the diode 106 connected in antiparallel with the IGBT 105. ZVS and ZCS turn-off are realized by turning off the IGBT 104 during a period in which a current flows through the diode 106.

  At this time, the resonance current IL109 flows through the path of the heating coil 109, the DC cut capacitor 110, the resonance capacitor 111, and the diode 106, and the path of the resonance capacitor 111 and the resonance reactor.

  As described above, by repeating the above operation, the resonance frequency determined by the resonance capacitor 111 and the resonance reactor 112 from the power supply circuit including the commercial power supply 101, the diode bridge, the smoothing choke 114, and the smoothing capacitor 113 via the inverter 10 is obtained. A high-frequency current having a resonance frequency determined by the heating coil 109 and the resonance capacitor 111 is superimposed on the high-frequency current, so that two types of high-frequency current can be supplied to the heating coil, and the object to be heated is induced by the magnetic flux generated from the heating coil 111. Heated.

  The power supplied to the object to be heated can be adjusted by controlling the driving frequency of the upper and lower arms 10.

  As in this embodiment, the current flowing through the resonance circuit becomes a sine wave shape due to the inductance of the heating coil and the resonance capacitor, and the resonance current advances from the voltage at point d, that is, the output voltage of the inverter, and becomes a phase.

  Therefore, when the IGBT is turned on, switching is performed in a state where the voltage between the collector and the emitter is zero volts and zero current, so that no turn-on loss occurs.

  Further, by configuring the full bridge inverter shown in FIG. 6, a voltage twice as large as the half bridge is applied to the heating coil, so that the number of turns of the heating coil can be increased, and high efficiency can be achieved.

Example 4
FIG. 11 is a circuit configuration diagram of an electromagnetic induction heating device according to the fourth embodiment of the present invention.

  The circuit configuration of FIG. 11 is characterized in that a relay 1101 is connected in parallel with the resonant reactor 112 and the resonant capacitor 111 in the circuit configuration of FIG.

  When heating an object to be heated having a low resistance such as copper or aluminum, the relay 1101 is turned off and heated in the same manner as in the first embodiment.

  On the other hand, when heating a magnetic object to be heated such as iron, the resonance reactor 112 and the resonance capacitor 111 can be bypassed by turning on the relay 1101. Thereby, a resonance current flows at a resonance frequency determined by the heating coil 109 and the DC cut capacitor 110, and induction heating is performed.

  Since non-magnetic heating objects such as aluminum and copper have a small equivalent resistance, it is necessary to increase the number of turns of the heating coil and increase the equivalent resistance by increasing the frequency.

  However, there are limitations due to restrictions on the size and shape of the device and the frequency band that can be used. Therefore, the equivalent resistance is increased by superimposing a harmonic component on the fundamental frequency.

  However, as shown in FIG. 2 (1), when the frequency is increased, the equivalent resistance of a magnetic object to be heated, such as iron, is greatly increased, and the commercial power supply voltage does not receive input power and cannot be heated. There is a problem.

  Therefore, by bypassing the parallel resonance circuit of the resonance capacitor 112 and the resonance reactor 111 by the relay 1101 as in the embodiment, a resonance current flows at the resonance frequency of the heating coil 109 and the DC cut capacitor 110.

  The DC cut capacitor 110 at this time has a capacity of several μF, and can be set to a frequency suitable for heating iron.

  Thus, in aluminum heating, heating is performed with a harmonic superposition current, while in iron heating, heating is performed with a normal primary resonance current, so that an optimum heating method can be obtained according to the material of the object to be heated. It becomes possible to heat efficiently.

(Example 5)
FIG. 12 is a circuit configuration diagram of an electromagnetic induction heating device according to the fifth embodiment of the present invention. The circuit configuration is that the heating coil 109 in FIG. 1 is a choke coil 1201, and the resonance reactor 112 is a heating coil 1202.

  Next, the operation mode will be described with reference to the timing chart shown in FIG.

  Here, the voltage at point d in FIG. 12 is Vd, the current flowing through the IGBT 103 and the diode 105 is Ic103, and the current flowing through the IGBT 104 and the diode 106 is Ic104.

  The current flowing through the choke coil 1201 is IL1201, the parallel resonance current flowing through the heating coil 1202 is IL1202, the voltage at the point c is defined as Vc, and the direction from the point d to the point c in FIG. 12 is defined as positive.

(Mode 1)
When the IGBT 103 is turned on and the IGBT 103 is turned on and the stored energy of the choke coil 1201 becomes zero, the polarity of the resonance current IL1201 changes from negative to positive, and the path from the smoothing capacitor 113 to the IGBT 103, choke coil 1201, DC cut capacitor 110, and capacitor 111 Thus, a resonance current IL1201 flows and a parallel resonance current IL1202 (in the direction of the arrow in the figure) flows through the path of the resonance capacitor 111 and the heating coil 1202.

(Mode 2)
Next, when the IGBT 103 is turned off, the resonance current IL1201 has a positive polarity. This current charges the upper arm snubber capacitor 107 and discharges the lower arm snubber capacitor 108, and the voltage Vd at the point d gradually increases. descend.

  After that, when a forward voltage is applied to the diode 105, the resonance current IL 1201 flows as a recirculation current through the choke coil 1201, the DC cut capacitor 110, the resonance capacitor 111, and the diode 106, and the resonance capacitor 111 and the heating coil 1202. The path is followed by a parallel resonant current IL1202.

(Mode 3)
Next, when the IGBT 104 is turned on and the accumulated energy of the choke coil 1201 becomes zero, the polarity of the resonance current IL1201 changes from positive to negative, and the resonance current IL1201 passes through the path of the resonance capacitor 111, the DC cut capacitor 110, the choke coil 1201, and the IGBT 104. Flows in the direction opposite to the arrow in the figure, the parallel resonance current IL1202 is reversed (in the direction opposite to the arrow in the figure), and flows through the path of the resonance capacitor 111 and the heating coil 1202.

  At this time, since the IGBT 104 keeps the gate voltage on during the period in which the current flows through the diode 106, ZCS and ZVS turn-on without switching loss are realized.

(Mode 4)
Next, when the IGBT 104 is turned off, the resonance current IL1201 has a negative polarity. This current charges the lower arm snubber capacitor 108, discharges the upper arm snubber capacitor 107, and the voltage Vd at the point d gradually increases. To rise.

  After that, when a forward voltage is applied to the diode 105, the resonance current IL109 flows as a circulating current through the path of the heating coil 109, the diode 105, the smoothing capacitor 113, the resonance capacitor 111, and the DC cut capacitor 110, and the parallel resonance current IL1202 Continues to flow in the path of the resonant capacitor 111 and the heating coil 1202.

  By repeating the above operation, a high-frequency magnetic field is generated from the heating coil, and an eddy current flows through the pan by the magnetic field to heat the pan itself and heat it. In this way, the current flowing through the inverter is suppressed by the choke coil 1201 by connecting the parallel resonance circuit from the output point of the inverter through the choke coil.

  On the other hand, in the parallel resonance circuit, an inverter current flows through the resonance capacitor 111, and a current flows through the heating coil 1202 from a voltage charged in the resonance capacitor 111 due to parallel resonance between the resonance capacitor 111 and the heating coil 1202. The resonance current IL1201 flowing through the choke coil 1201 at this time is determined by the power supply voltage, the impedance of the choke coil 1201, and the impedance of the parallel resonance circuit.

  The voltage generated in the parallel resonance circuit is determined by the resonance current IL1201 and the impedance of the parallel resonance circuit, and a current flows through the parallel resonance circuit by this voltage. That is, since a large current due to resonance flows through the heating coil and the current can be suppressed through the choke coil through the inverter, the loss of the inverter can be significantly suppressed.

(Example 6)
FIG. 13: is a circuit block diagram of the electromagnetic induction heating apparatus which is 6th Embodiment of this invention.

  The circuit configuration of FIG. 13 is characterized in that a relay 1301 is connected in parallel with the choke coil 301 in the circuit configuration of FIG.

  When heating a low-resistance object to be heated such as copper or aluminum, the relay 1301 is turned off and heated in the same manner as in the fifth embodiment. On the other hand, when heating a magnetic object such as iron, the choke coil 301 can be bypassed by turning on the relay 1301.

  Thereby, a resonance current flows at a series resonance frequency determined by the heating coil 201 and the DC cut capacitor 110, and induction heating is performed. At this time, the resonance capacitor 111 has a very small capacity compared to the DC cut capacitor, and therefore does not affect the operation.

  Since non-magnetic heating objects such as aluminum and copper have a small equivalent resistance, it is necessary to increase the number of turns of the heating coil and increase the equivalent resistance by increasing the frequency. However, there are limitations due to restrictions on the shape of the device and the frequency band that can be used.

  Therefore, the equivalent resistance is increased by superimposing a harmonic component on the fundamental frequency. However, as shown in FIG. 2 (1), when the frequency is increased, the equivalent resistance of a magnetic object to be heated, such as iron, is greatly increased, and the commercial power supply voltage does not receive input power and cannot be heated. There is a problem.

  Thus, by bypassing the choke coil 301 by the relay 1301 as in the present embodiment, a resonance current flows at the series resonance frequency of the heating coil 201 and the DC cut capacitor 110. The DC cut capacitor 110 at this time has a capacity of several μF, and can be set to a frequency suitable for heating iron.

  As described above, in the aluminum heating, the inverter current can be significantly suppressed by the choke coil. On the other hand, in the iron heating, by heating with the normal primary resonance current, an optimum heating method according to the material of the object to be heated can be obtained. It becomes possible to heat with high efficiency.

(Example 7)
A seventh embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the switching elements 103 and 104 and the diodes 105 and 106 in FIGS. 1 to 13 are silicon carbide devices (hereinafter referred to as SiC devices).

  FIG. 14 shows the relationship between the breakdown voltage and on-resistance of a silicon device (hereinafter referred to as Si device) and a silicon carbide device (hereinafter referred to as SiC device). In general, it is known that a SiC device can significantly improve a trade-off between breakdown voltage and on-resistance compared to a Si device.

  As shown in FIG. 14, when the Si device and the SiC device are compared with the 600 V element, the on-resistance is 1/1000 times higher in the SiC device than in the Si device, and can be greatly reduced.

  In current induction heating devices using Si devices, cooling devices and heat dissipation fins are indispensable. By using such SiC devices, element loss can be greatly reduced. It becomes possible to make them unnecessary.

  As described above, when the diode is changed from the Si device to the SiC device, the loss can be greatly reduced, the cooling device and the heat radiation fin are not required, and the size and cost can be greatly reduced.

  As a result, an induction heating apparatus having a structure in which a roaster is disposed on the entire lower surface of the top rate as shown in FIGS.

  Reference numeral 1501 denotes a top plate, 1502 denotes a roaster, 1503 denotes a window, 1504 denotes a handle, 1601 denotes a net, and 1602 denotes a rail.

  In the seventh embodiment, the SiC device has been described as an example. However, the present invention is not limited to SiC, and the same effect can be obtained in a wide band gap device such as diamond or gallium nitride (GaN). It will be apparent to those skilled in the art.

  According to the first to fifth embodiments described above, the example of the IGBT has been mainly described. However, the induction heating device of the present invention is not limited to the IGBT, but a power MOSFET, other insulated gate semiconductor devices, and bipolar transistors. It will be apparent to those skilled in the art that the same effect can be obtained in.

The main features of the above embodiment are summarized below.
(1). (Characteristics corresponding to FIG. 1 and FIG. 3)
The switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element includes a diode in antiparallel, and a DC suppression capacitor for suppressing a DC current is connected to the output terminal of the upper and lower arms, A first resonance load circuit including a heating coil for induction heating and a first resonance capacitor; a choke coil in parallel with the first resonance capacitor; and a first resonance capacitor and a choke coil including the choke coil. 2 resonance circuits are provided.
(2). (Characteristics corresponding to FIG. 5)
The upper and lower arm switching elements are power semiconductor switching elements, the power semiconductor switching elements are provided with diodes in antiparallel, the upper arms are provided with a first snubber capacitor in parallel, and the lower arms are connected in series in parallel. A second snubber capacitor and a switching element, and a DC suppression capacitor that suppresses a DC current is connected to the output terminals of the upper and lower arms, and includes a heating coil that induction-heats an object to be heated and a first resonance capacitor. A first resonant load circuit, a choke coil in parallel with the first resonant capacitor, and a second resonant circuit including the first resonant capacitor and the choke coil.
(3). (Features corresponding to FIGS. 7 and 8)
The switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element includes a diode in antiparallel, and a DC suppression capacitor for suppressing a DC current is connected to the output terminal of the upper and lower arms, A first resonance load circuit including a first heating coil for induction heating and a first resonance capacitor; and a second heating coil for induction heating of an object to be heated in parallel with the first resonance capacitor. And a second resonant circuit including a first resonant capacitor and the second heating coil.
(4). (Characteristics corresponding to FIG. 9)
A DC voltage source is connected to the upper and lower arms via an inductor, the switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element includes a diode in antiparallel, and the output terminal of the upper and lower arms, A DC suppression capacitor that suppresses a DC current is connected, and includes a first resonance load circuit that includes a heating coil that induction-heats an object to be heated and a first resonance capacitor, and is choked in parallel with the first resonance capacitor. An induction heating apparatus comprising a coil and a second resonance circuit including a first resonance capacitor and the choke coil.
(5). (Features corresponding to FIG. 12)
The switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element is provided with a diode in antiparallel, a DC suppression capacitor for suppressing DC current is connected to the output terminal of the upper and lower arms, A first resonance load circuit including one resonance capacitor, a heating coil for inductively heating an object to be heated in parallel with the first resonance capacitor, and a first resonance capacitor and the choke coil. 2 resonance circuits are provided.
(6). (Characteristics corresponding to FIG. 11)
A switch is connected in parallel with the choke coil.

It is a circuit block diagram of the induction heating apparatus concerning the 1st Example of this invention. It is a graph showing the relationship between the number of turns of the heating coil of the electromagnetic induction heating apparatus which is an Example of FIG. 1, and an equivalent resistance. It is a graph showing the relationship between the winding number of the heating coil of the electromagnetic induction heating apparatus which is the Example of FIG. 1, and an equivalent inductance. It is a time chart which shows the operation | movement of FIG. It is a circuit diagram which shows the modification of FIG. It is a circuit diagram which shows the modification of FIG. It is a circuit block diagram of the induction heating apparatus concerning the 2nd Example of this invention. It is a circuit diagram which shows the modification of FIG. It is a circuit block diagram of the induction heating apparatus concerning the 3rd Example of this invention. It is an operation | movement time chart of the induction heating apparatus concerning the 3rd Example of this invention. It is a circuit block diagram of the induction heating apparatus concerning the 4th Example of this invention. It is a circuit block diagram of the induction heating apparatus concerning the 5th Example of this invention. It is a circuit block diagram of the induction heating apparatus concerning the 6th Example of this invention. It is a graph which shows the effect concerning the 7th Example of this invention. It is a block diagram of the induction heating apparatus which employ | adopted the said Example of this invention. It is a block diagram of the induction heating apparatus which employ | adopted the said Example of this invention. It is an operation | movement time chart of the induction heating apparatus concerning the 5th Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 109 ... Heating coil, 111 resonance capacitor, 112 ... Resonance reactor, 103 ... IGBT, 104 ... IGBT, 109 ... Resonance current IL, 112 ... Resonance current IL

Claims (5)

A resonance load circuit including an object to be heated; and an inverter that converts a DC voltage into an AC voltage and supplies electric power to the resonance load circuit. The inverter includes at least two switching elements connected in series. In the induction heating apparatus comprising at least one set of upper and lower arms,
The resonant load circuit includes at least two, and a current that flows at the resonance frequency of one resonance load circuit is superimposed on a current that flows at the resonance frequency of the other resonance load circuit,
The switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element includes a diode in antiparallel, and a DC suppression capacitor that suppresses a DC current is connected to an output terminal of the upper and lower arms, comprising a first resonant load circuit configured by the first heating coil and a first resonance capacitor to inductively heat a second heating coil you induction heating an object in parallel with said first resonance capacitor the provided induction heating apparatus characterized by comprising a second resonant circuit including a first resonance capacitor and the second heating coil. In the induction heating device according to claim 1,
The switching element of the upper and lower arms is a power semiconductor switching element, the power semiconductor switching element is provided with a diode in reverse parallel, the upper arm is provided with a first snubber capacitor in parallel, and the lower arm is connected in parallel with a series connection. A first snubber capacitor and a switching element, a DC suppression capacitor for suppressing a DC current is connected to the output terminals of the upper and lower arms, and a first heating coil for inductively heating an object to be heated and a first resonance A second resonance circuit including a first resonance load circuit including a capacitor, a second heating coil in parallel with the first resonance capacitor, and including the first resonance capacitor and the second heating coil; An induction heating apparatus comprising: In the induction heating device according to claim 1,
A DC voltage source for generating the DC voltage;
The DC voltage source is connected to the upper and lower arms via an inductor, the switching elements of the upper and lower arms are power semiconductor switching elements, the power semiconductor switching elements include diodes in antiparallel, and the output terminals of the upper and lower arms Are connected to a DC suppression capacitor that suppresses a DC current, and includes a first resonance load circuit including a first heating coil that induction-heats an object to be heated and a first resonance capacitor, and the first resonance An induction heating apparatus comprising a second heating coil in parallel with a capacitor, and a second resonance circuit including the first resonance capacitor and the second heating coil. In the induction heating device according to any one of claims 1 to 3,
An induction heating apparatus, wherein the diode and the switching element are made of a wide band gap device. In the induction heating device according to claim 2,
An electromagnetic induction heating apparatus comprising switch means for separating the snubber capacitor from the upper and lower arms.

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