JP2004259665A - Induction heating method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the input power of each induction heating coil by suppressing the inverter output even when the mutual induction voltage increases with the increase of input power to the induction heating coil. <P>SOLUTION: The basic structure of an induction heating device 10 comprises a plurality of induction heating coils 56 (56m, 56s) and resonance type inverters 52 (52m, 52s) for zone controlling each of these. A component for generating induced electromotive force of reverse polarity is provided at the circuit equipped with the induction heating coil 56 for generating mutual induction. The component for generating induced electromotive force of reverse polarity may be, for example, a reverse connection transformer 64 or the like that is constructed of a tuning coil 63 provided facing each other so that each polarity may become inverse due to reversed direction or the like of the winding direction of the coil. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an induction heating method and apparatus, and more particularly to an induction heating method and apparatus suitable for suppressing the influence of mutual induction voltage in a control circuit requiring a plurality of induction heating coils.
[0002]
[Prior art]
2. Description of the Related Art In recent years, induction heating coils that have good heating efficiency and high thermal efficiency have been used in various fields. However, when trying to arbitrarily adjust the temperature at a plurality of locations, it is necessary to arrange a plurality of induction heating coils and control them individually. When a plurality of induction heating coils arranged adjacently are activated simultaneously, interference occurs between the induction heating coils due to the influence of the mutual induction voltage. This interference makes it impossible to control the power supplied to each induction heating coil, and may make it impossible to control the temperature of the object to be heated.
[0003]
As means for suppressing or avoiding the influence of such mutual induction voltage, for example, the invention of Patent Document 1 can be mentioned. The invention of Patent Literature 1 controls one of a plurality of heating units as a main heating unit and controls the other subordinate units. Specifically, when operating a plurality of heating units, the phase difference of each current is detected, the inverter provided in each heating unit is controlled, and the influence of the mutual induction voltage is made to depend on the main heating unit. It is to avoid.
[0004]
[Patent Document 1]
JP-A-2002-260833
[Problems to be solved by the invention]
According to the circuit having the configuration as in Patent Literature 1, it is possible to avoid the influence of the mutual induction voltage, control the input power of each induction heating coil individually, and arbitrarily control the temperature of the object to be heated. is there. However, in the circuit having the configuration of Patent Literature 1, when the mutual induction voltage increases due to an increase in input power or the like, an inverter having a large capacity is required to increase the inverter output voltage.
[0006]
An object of the present invention is to provide a method and an apparatus for suppressing mutual induction voltage that can control the output power of each induction heating coil while suppressing the inverter output even when the mutual induction voltage increases.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an induction heating method according to the present invention is directed to an induction heating method that suppresses a mutual induction voltage generated when a current is supplied to a plurality of induction heating coils arranged adjacent to each other. The influence of the mutual induction voltage between the circuits is canceled or partially canceled by generating an electromotive force of the opposite polarity in the circuit of the induction heating coil causing the mutual induction, and the power supplied to each induction heating coil is converted to an inverter. , To avoid the influence of the mutual induction voltage.
[0008]
In addition, the induction heating device includes a resonance type inverter that performs zone control of each of the plurality of induction heating coils, and a circuit that includes an induction heating coil that generates mutual induction includes a component that generates an induced electromotive force of opposite polarity. It is characterized by having.
[0009]
[Action]
In the induction heating method as described above, the influence of the mutual induction voltage between the circuits of the induction heating coil generating the mutual induction voltage is offset by generating the electromotive force of the opposite polarity in the circuit of the induction heating coil generating the mutual induction voltage. After partially canceling out, and controlling the power supplied to each induction heating coil by feedback control with an inverter to avoid the influence of the mutual induction voltage, the mutual induction voltage having a large influence is canceled out. Since the mutual induced voltage which has not been canceled is avoided by the control, it is possible to avoid an increase in the inverter capacity due to an increase in the mutual induced voltage.
[0010]
As a circuit for realizing the above method, a circuit including a resonance type inverter for zone-controlling each of a plurality of induction heating coils, and a circuit including an induction heating coil for generating mutual induction generates an induced electromotive force of opposite polarity. By providing an element, the mutual induction voltage exerting a large effect is canceled out or partially canceled out by the component generating the induced electromotive force of the opposite polarity, and then the influence of the mutual induction voltage is avoided by further inverter control. Therefore, substantially all of the effects of the mutual guidance can be avoided, and the effect of the above method can be obtained. Further, by providing two means for avoiding the mutual induction voltage, the load on the device or the device itself can be reduced as compared with the case where only one means is used. For example, in the case of only inverter control, an increase in capacity due to an increase in mutual induction voltage cannot be denied as described above. If it is intended to completely avoid the mutual induction voltage only by the components generating the induced electromotive force of the opposite polarity, as the number of induction heating coils increases, the number of coils affected by the mutual induction voltage increases as the number of induction heating coils increases. Must be increased in accordance with Therefore, it is not realistic in terms of installation cost, maintenance, control / adjustment, and the like.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an induction heating device according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. The induction heating device 10 includes a power supply unit 30 for supplying electric power, a forward conversion unit 40 for rectifying a supply current, a drive control circuit 20 (20 m, 20 s), and a load coil unit 22 (22 m, 22 s). And a plurality of heating units.
[0012]
In the present embodiment, a reverse connection transformer 64 is a component that generates an interference electromotive force (induction electromotive force) generated by the influence (interference) of the mutual induction voltage of the plurality of induction heating coils 56, which will be described later. , And the power is individually controlled by the inverter 52 which can control the plurality of induction heating coils 56 respectively. Thus, the influence of mutual induction can be avoided even if the input power to each of the adjacent induction heating coils 56 is individually controlled, and the object to be heated is zone-controlled to have the required temperature distribution. be able to.
[0013]
The reverse connection transformer 64 is provided with an adjustment coil provided in the load coil portion 22 having the adjacent induction heating coil 56 so that the polarity thereof is reversed, for example, when the winding direction of the coil is reversed. 63. In other words, if currents in opposite directions are applied to both the primary coil and the secondary coil of the transformer, magnetic fields of opposite polarities are generated in the mutual coils and cancel out the mutual induced voltage (electromotive force due to the magnetic field). The principle is that they fit. According to the reverse connection transformer 64, the interference electromotive force (induced electromotive force) generated in the adjacent circuit where the influence (interference) of the mutual induction voltage is the largest is canceled or the entire mutual induction voltage exerting the influence is canceled out. Are partly canceled to reduce the load on the inverter 52.
[0014]
Therefore, in the load coil section 22 of each heating unit in the present embodiment, the adjustment coil 63 is provided in each of the circuits that generate the mutual induction voltage so as to configure the reverse connection transformer 64. Further, an arbitrary induction heating coil 56m and its drive control circuit 20m are used as a main unit, and the other induction heating coils 56s1, 56s2... 56sx and drive control circuits 20s1, 20s2.
[0015]
In this embodiment, each of the main unit and the sub-unit is driven by receiving power supply from the common power supply unit 30 via the forward conversion unit 40, and is driven by the main chopper 50m and the sub-choppers 50s (s1 to 50s). sx). An inverter 52 (52m, 52s) is connected to the output side of the chopper 50. In the load coil section 22 (22 m, 22 s) including the induction heating coil 56 on the output side of each inverter 52, a capacitor 54 (54 m, 54 s) is connected in series with the induction heating coil 56 to form a series resonance circuit. I have. Further, one or two reverse connection transformers 64 are configured in series with the induction heating coil 56 in the load coil section 22 (22m, 22s). Since the polarity of the adjustment coil 63 constituting the reverse connection transformer 64 is opposite to that of the opposing coil, it is desirable that the mutual induction voltage between the adjacent circuits having the largest influence of the mutual induction voltage be offset. With these configurations, it is possible to control the heating of the object to be heated while controlling each of the induction heating coils 56.
[0016]
By the way, in this embodiment, in order to avoid the influence of the mutual induction voltage generated by operating the plurality of induction heating coils 56, the interference electromotive force (induction electromotive force) generated between the adjacent induction heating coils 56 is canceled. In addition, the power supplied to the induction heating coil 56 in the plurality of heating units is adjusted by controlling the inverter 52. For this reason, each sub-unit is provided with an input power detection controller 62 for inputting the power input to the load coil 22m of the main unit and the power input to the load coil 22s of the sub-unit. Then, the drive of the inverter 52s is controlled so as to avoid the influence of the mutual induction voltage generated in both. Thereby, even if the input power required by the induction heating coil 56 is adjusted in each of the choppers 50 of the main unit and the subunit, the influence of the mutual induction between the adjacent induction heating coils 56 is completely or minimized. Since the power can be suppressed, the power adjustment can be performed stably, the temperature of the object to be heated heated by each induction heating coil 56 can be set arbitrarily, and the temperature can be raised at a high speed. , It is possible to control the zone. In addition, by configuring the reverse connection transformer 64 in each load coil section 22 where a mutual induction voltage is generated, the influence of the largest mutual induction voltage can be canceled. Therefore, even if the input power to the induction heating coil 56 increases and the mutual induction voltage increases accordingly, the output and capacity of the inverter 52 that controls the input power can be reduced. Further, a current transformer 58 (58 m, 58 s) is provided in the load coil section 22 (22 m, 22 s) in series with the induction heating coil 56 so that the output current is fed back to the input power detection controller 62. It has become. A power control signal is sent to the inverter 52 based on the feedback value.
[0017]
In the embodiment as described above, each of the load coil units 22 of the plurality of heating units having the induction heating coil 56 is configured with the reverse connection transformer 64, thereby canceling the mutual induction voltage having a great effect. Alternatively, after partially canceling, the influence of the mutual induction voltage is further avoided by the inverter control, so that substantially all of the influence of the mutual induction can be avoided, and the capacity of the inverter 52 can be reduced. Further, by using two types of means for avoiding the mutual induction voltage, ie, the reverse connection transformer 64 and the inverter 52, the burden on the device or the load on the device is reduced as compared with the case where one of the means is used to avoid the mutual induction voltage. The device itself can be reduced. For example, in the case of only the inverter control, an increase in capacity due to an increase in the mutual induction voltage cannot be denied. When it is intended to completely avoid the mutual induction voltage using only the reverse connection transformer 64, as the number of the induction heating coils 56 increases, the number of the reverse connection transformers 64 is changed to the number of coils affected by the mutual induction voltage. Must increase according to the number. Therefore, it is not realistic in terms of installation cost, maintenance, control / adjustment, and the like.
[0018]
In the above embodiment, an iron core (not shown) may be inserted into the adjustment coil 63 of the reverse connection transformer 64 to increase the efficiency of the reverse induction.
Further, in the embodiment, the component for generating the induced electromotive force of the opposite polarity is the reverse connection transformer 64, but is not limited thereto, and the induced electromotive force of the opposite polarity may be generated by a bus bar or the like.
[0019]
【The invention's effect】
In the above embodiment, in the induction heating method for suppressing a mutual induction voltage generated when a current is supplied to a plurality of induction heating coils arranged adjacent to each other, the influence of the mutual induction voltage between the circuits of the induction heating coil causing the mutual induction is reduced. Generating an electromotive force of the opposite polarity in the circuit of the induction heating coil that causes the mutual induction to cancel or partially cancel the power, and feedback-control the power supplied to each induction heating coil by an inverter to control the mutual induction voltage. By avoiding the influence, the mutual induced voltage that has a large influence is canceled out, and then the mutual induced voltage that is not canceled out is controlled by the inverter control. The accompanying increase in inverter capacity can be avoided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of an embodiment of the present invention.
[Explanation of symbols]
Reference numeral 10: induction heating device, 20: drive control circuit, 22: load coil unit, 30: power supply unit, 40: forward conversion unit, 50: chopper, 52: inverter 54, a condenser, 56, an induction heating coil, 58, a current transformer, 62, a supplied power detection controller, 63, an adjustment coil, 64, a reverse connection transformer.

Claims (2)

In an induction heating method for suppressing a mutual induction voltage generated when a current is supplied to a plurality of induction heating coils arranged adjacent to each other, the influence of the mutual induction voltage between the circuits of the induction heating coil that causes the mutual induction is reduced. To generate or cancel the electromotive force of the opposite polarity in the generated induction heating coil circuit, and to feedback-control the power supplied to each induction heating coil by an inverter to avoid the influence of the mutual induction voltage. An induction heating method characterized in that: A circuit comprising a resonance type inverter for zone-controlling each of a plurality of induction heating coils, and a circuit comprising an induction heating coil for generating mutual induction includes a component for generating an induced electromotive force of opposite polarity. apparatus.

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