JP2008288222A - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lessen electric stress generated on a formation component of an inverter circuit caused by a magnetic flux applied from the outside at the time of non-operation of an inverter. <P>SOLUTION: When an inverter circuit 4 is not operated, the electric stress carelessly applied on the formation component of the inverter circuit 4 caused by induced electromotive force induced on a heating coil 5 by the leaked magnetic flux from an external apparatus can be relieved or prevented since a route releasing means 9 intercepts a desired current route. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an induction heating apparatus such as a heating cooker used in general homes, restaurants, offices, factories, and the like.

A conventional induction heating apparatus will be described by taking an induction heating cooker as an example. There are those that detect the material of a pan or the like to be heated, switch the electrical parameters in the inverter circuit according to the material, and realize inverter operation suitable for the material (for example, Patent Documents 1 and 2). reference).
JP 2003-151747 A JP 2003-257610 A

  However, the above conventional configuration obtains a desired induction heating output according to the material of the object to be heated when the inverter circuit is operating, and the electrical and thermal duties of the electrical components in the inverter circuit are appropriate. Therefore, the parameters are switched so that the influence of the magnetic flux applied from the outside when the inverter circuit is not operated is not taken into consideration. That is, when another induction heating cooker, induction heating rice cooker, induction motor device or the like is used on this induction heating cooker, the magnetic flux leaking from the upper device is induced in the lower conventional induction. A component of the inverter circuit is generated when an induction current or an induced electromotive force is generated in a current path in the inverter circuit where a high-frequency current necessary for induction heating should flow when the inverter circuit is operated. It is said that excessive electrical stress is applied to the resonant capacitor and switching element, and reliability deterioration and worst parts are destroyed, and the lower induction heating cooker may become unusable. Had problems.

  In order to avoid this situation, there is a method of increasing the electrical tolerance of the components in the inverter circuit. However, tolerances that deviate from the general-purpose area of these components are required, which deteriorates the yield and costs of component production. It has the subject that it may become up or manufacture becomes impossible.

  Furthermore, it is not impossible to reduce the electrical stress applied to the component by increasing or decreasing the inductance of the heating coil and the capacitance of the resonant capacitor. It became a barrier when selecting parameters, and there was a problem that an increase in the burden of equipment design was a concern.

  The present invention solves the above-described problem. Even when the inverter circuit is not operating, it receives a magnetic flux from the outside of the device and affects the inverter circuit. A first object of the present invention is to provide an induction heating device that is relatively easy and reliable to prevent electrical stress from being applied to the electronic parts of the present invention, that is inexpensive, easy to use, and highly reliable. .

  A second object of the path opening means provided to solve the above problems is to reduce the size, reduce the cost, ensure durability, and ensure reliability.

In order to achieve the first object, an induction heating apparatus of the present invention includes a heating coil, a resonant capacitor, and switching means, and a high-frequency alternating current obtained by driving the switching means with a direct current obtained by rectifying and smoothing an alternating current power supply. And inducing the object to be heated by generating a high-frequency current in a current path including the heating coil and the resonance capacitor, or the heating coil and the switching means, or the heating coil, the resonance capacitor, and the switching means. An inverter circuit for heating, and when the inverter circuit is not operating, has a path opening means for making at least one of the components of the current path non-conductive.

  As a result, even when the inverter circuit is not operating, it receives magnetic flux from the outside of the device and affects the inverter circuit. The application of electrical stress can be suppressed or prevented.

  The induction heating device according to the present invention has a relatively simple configuration in which a failure of a device due to an inadvertent application of electrical stress to its components when the inverter circuit is not in operation due to a leakage magnetic flux from an external device. Thus, it can be effectively mitigated or prevented.

  A first invention includes a heating coil, a resonance capacitor, and switching means, and converts a direct current obtained by rectifying and smoothing an AC power source into a high frequency alternating current by driving the switching means, and the heating coil and the resonance capacitor, or An inverter circuit for inductively heating an object to be heated by generating a high-frequency current in a current path including the heating coil, the resonance capacitor, and the switching means. It is necessary to close the path opening means and inductively heat the object to be heated during operation of the inverter circuit by having a path opening means that makes at least one of the current path components non-conductive during operation. Secure current path, switching means conduction time or driving cycle, or The conduction ratio is varied by the driving means to change the high-frequency current supplied to the heating coil, and by this high-frequency current, the heated object such as a pan is induction-heated by the high-frequency magnetic flux generated from the heating coil, and the heated object is heated. The induction heating output can be controlled, and when the inverter circuit is not operating, the current path can be interrupted by opening the path opening means, so that the magnetic flux applied to the heating coil from the outside of the induction heating device, for example, Depending on the case where another induction heating device or induction motor device is placed and operated so as to face the heating coil of the induction heating device and this leakage magnetic flux crosses the heating coil of the induction heating device of the present invention, etc. When this current path is closed, generation of induced electromotive force or induced current can be suppressed or suppressed. Switching means, resonant capacitor, an electrical stress applied to the heating coil or the like can be reduced or nil is.

  In the second invention, in particular, the path opening means of the first invention is configured such that one end of the heating coil is made non-conductive, so that the magnetic flux applied to the heating coil from the outside of the induction heating device is used in the inverter circuit. Since an induced electromotive force or an induced current can be prevented from being induced in the current path, electrical stress applied to the switching means, the resonance capacitor, and the like that are components of the inverter circuit can be eliminated.

In the third aspect of the invention, in particular, the path opening means of the first aspect of the invention is configured such that one end of the switching means is made non-conductive, so that the magnetic flux applied to the heating coil from the outside of the induction heating apparatus Inductive electromotive force or induced current in the current path through the switching means is not cut off and induced when the inverter circuit is not in operation, and is generally composed of a semiconductor element, and is less susceptible to electrical stress than a heating coil or a resonant capacitor. Alternatively, it is possible to reduce the electrical stress of the switching means that is difficult to withstand high electrical stress. In addition, generally, the high-frequency current value flowing through each component when the object to be heated is inductively heated becomes smaller when the heating coil current is compared with the switching means current. Therefore, the current capacity of the path opening means can be reduced, and the path opening means can be reduced in size and cost.

  In the fourth aspect of the invention, in particular, the path opening means of the first aspect of the invention is configured such that one end of the resonance capacitor is made non-conductive, so that the magnetic flux applied to the heating coil from the outside of the induction heating device is increased in the inverter circuit. When the inverter circuit is not operating, the induced electromotive force or the induced current is not cut off and induced in the current path through the resonance capacitor, and the electrical stress applied to the components of the inverter circuit such as the switching means and the heating coil can be reduced. In addition, generally, when the object to be heated is induction-heated, the value of the high-frequency current flowing through each component becomes smaller when the heating coil current is compared with the resonance capacitor current. Therefore, the current capacity of the path opening means can be reduced, and the path opening means can be reduced in size and cost.

  According to a fifth aspect of the present invention, in particular, when the path opening means according to any one of the first to fourth aspects has an open / close contact, the induction heating device Since the electromotive force induced by the magnetic flux applied to the heating coil from the outside is generated at both open ends of the path opening means, if the path opening means is constituted by a semiconductor switch, the semiconductor switch can withstand this induced electromotive force. It is necessary to use the one with the allowable value of high withstand voltage, which is the same as changing the switching means to the high withstand voltage value, but if the path opening means is composed of switching contacts, the withstand voltage will be open A high breakdown voltage can be realized by a relatively simple method of securing the distance between the contacts.

  The sixth invention has operation setting means for setting the operation of the inverter circuit of any one of the first to fifth inventions, and when the operation setting means is set, the path opening means is By configuring the inverter circuit to start operation after the passage of the first predetermined time after the passage of the path, the operation setting means sets the operation of the inverter circuit until the path opening means changes from the non-conductive state to the conductive state. Since the inverter circuit starts to operate after the path opening means is surely turned on by setting the first predetermined time or more as the first predetermined time, the path opening means can be turned on by the zero current switching operation. It becomes easy to reduce the switching loss of the opening means and to secure the durability of the contacts.

  According to a seventh aspect of the invention, in particular, when the operation setting means of the sixth aspect of the invention is set to stop, the inverter circuit stops and the path opening means makes the path non-conductive after the second predetermined time has elapsed. By setting the second predetermined time to be longer than the time from when the inverter circuit is set to stop by the operation setting means until the inverter circuit stops, the path opening means becomes conductive after the inverter circuit has stopped reliably. Since the state is changed to the non-conductive state, the path opening means can be made non-conductive by the zero current switching operation, the switching loss of the path opening means is reduced, the arc of the contact is prevented, etc., and the durability can be easily ensured.

  According to the eighth aspect of the present invention, the path opening means maintains the continuity while the operation setting means of the sixth or seventh aspect of the invention is set to operate. If the inverter circuit is stopped as a protective action against power failure or inverter circuit operation abnormality, the path open means can be maintained in a conductive state, and when the inverter circuit stops, the current flowing transiently is not interrupted. In addition, by inheriting the same operation as the case without the path opening means, the transient generated voltage and inflow current in each component of the inverter circuit are made equal to those without the path opening means, and the path opening means Unnecessary conduction / non-conduction is prevented, and when the path opening means is a switching contact type, the number of switching operations can be suppressed, and the durability and reliability of the contacts can be easily ensured.

  In particular, the ninth invention has a power failure detection means for detecting a power failure of the AC power supply of the eighth invention, and the route opening means while the power failure detection means detects a power failure and stops the inverter circuit. By maintaining the continuity, when the power failure detection means detects a power failure of the AC power supply, the inverter circuit is stopped in order to avoid instability of operation of the inverter circuit at the time of power failure recovery and electrical stress application. At this time, the conduction state of the path opening means can be maintained, and when the inverter circuit is stopped, the current that is flowing transiently is not interrupted, and the same operation as when there is no path opening means is inherited and the inverter circuit Transiently generated voltage and inflow current in each component of the inverter circuit is equivalent to when there is no path opening means, and transient generated voltage in each component of the inverter circuit due to the difference in timing when the path opening means becomes non-conductive In addition, the transitional operation when the inverter circuit is stopped is made constant by eliminating the change in current and inflow current, and unnecessary conduction / non-conduction of the path opening means is prevented, and the path opening means is a switching contact type. Can suppress the number of opening and closing operations, and can easily ensure the durability and reliability of the contacts.

  The tenth invention has an abnormality detection means for detecting an operation abnormality of the inverter circuit of the eighth invention, and when the abnormality detection means detects an abnormality, the operation of the inverter circuit is stopped and the path is opened. Since the means is configured to maintain continuity, when the abnormality detection means detects an abnormal operation of the inverter circuit, for example, an abnormal rise in the voltage across the switching means or the inflow current, in order to avoid a permanent failure of the inverter circuit Then, the operation of the inverter circuit is stopped. At this time, the conduction state of the path opening means can be maintained, and when the inverter circuit is stopped, the current that is flowing transiently is not interrupted, and the same operation as when there is no path opening means is inherited and the inverter circuit Transiently generated voltage and inflow current in each component of the inverter circuit is equivalent to when there is no path opening means, and transient generated voltage in each component of the inverter circuit due to the difference in timing when the path opening means becomes non-conductive In addition, the transitional operation when the inverter circuit is stopped is made constant by eliminating the change in current and inflow current, and unnecessary conduction / non-conduction of the path opening means is prevented, and the path opening means is a switching contact type. Can suppress the number of opening and closing operations, and can easily ensure the durability and reliability of the contacts.

  The eleventh invention has, in particular, contact abnormality detecting means for detecting abnormality of the contact of the path opening means of the fifth invention, and notification means for informing the operation setting state of the inverter circuit, wherein the contact abnormality means When the abnormality of the contact is detected, the inverter circuit is disabled, and the notification means notifies the abnormality of the contact of the path opening means or the operation of the inverter circuit. However, it is possible to detect a contact state abnormality such as non-conduction when the path opening means should be conductive, or conduction when the path opening means should be non-conductive. In addition, the notification means normally notifies the operation setting state of the inverter circuit, for example, the operation / non-operation of the inverter circuit, the induction heating output setting value to the heated object, etc. When the circuit is detected, by disabling the inverter circuit, when the path opening means should be conductive, the circuit remains open and the secondary circuit failure due to incomplete inverter circuit configuration is avoided. When the means should be non-conductive, electrical stress is applied to the components of the inverter circuit by applying the leakage magnetic flux from other induction heating type equipment to the heating coil of the induction heating device while remaining conductive. It is possible to notify the user that there is a possibility and prompt the user to take measures.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking an induction heating cooker as an example. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the induction heating apparatus in the first embodiment of the present invention.

In the induction heating cooker (induction heating apparatus) shown in FIG. 1, the rectifier circuit 2 is composed of a bridge-connected diode that rectifies the commercial power source (AC power source) 1, and the smoothing circuit 3 is composed of a choke coil 3a and a capacitor 3b. The inverter circuit (one voltage resonance type in the first embodiment) 4 includes switching means 4a and a resonance capacitor 4b, and the heating coil 5 is heated by a high-frequency current from the inverter circuit 4 to be heated such as a pot. A high frequency alternating magnetic field is applied to the body 6 to perform induction heating, and the control circuit 7 controls the operation of the inverter circuit 4 so that the switching means 4a is driven on and off, and the conduction time or drive cycle or conduction ratio of the switching means 4a. Drive means 8 for controlling the high-frequency current supplied to the heating coil 5 with variable power, the heating coil 5 and the resonance capacitor 4b, The heating coil 5 and the switching means 4a, or the path opening means 9 for switching at least one conduction / non-conduction of the current path comprising the heating coil 5, the resonance capacitor 4b and the switching means 4a, and the user to the object 6 to be heated The operation setting means 10 composed of a switch or the like for setting the operation state of the inverter circuit 4 to perform induction heating output setting, etc., and the contents set by the operation setting means 10 are displayed on the LED or LCD, or a buzzer or speaker. Informing means 11 for notifying, etc., power failure detecting means 12 for detecting a power failure of the commercial power source 1, abnormality detecting means 13 for detecting an operation abnormality of the inverter circuit 4, and contact abnormality detection for detecting abnormality of the path opening means 9 Means 14.

  In the first embodiment, first, the path opening means 9 is inserted on the high potential side of the switching means 4a, which is the current path between the heating coil 5 and the switching means 4a (when the path is opened, the switching means The case where 4a is on the low potential side will be described. Other cases will be described later.

  The notification means 11 informs the user of the setting of the induction heating output of the inverter circuit 4 performed by the user in the operation setting means 10, and based on this, the conduction time of the switching means 4a is varied by the driving means 8. The high-frequency current supplied to the heating coil 5 is changed, and the high-frequency magnetic flux generated from the heating coil 5 is used to induction-heat the heated body 6 such as a pan, and the induction heating output to the heated body 6 is also changed. Can be controlled.

  At this time, until the user sets the operation start of the inverter circuit 4 by the operation setting means 10, the path opening means 9 is in a non-conductive state, interrupts the current path between the heating coil 5 and the switching means 4a, and induction heating is performed. Magnetic flux applied to the heating coil 4a from the outside of the cooking device, for example, another induction heating type device or induction motor device instead of the heated object 6 such as a pan so as to face the heating coil 4a of the induction heating cooking device. If the current path is closed, such as when the leakage flux of the other device crosses the heating coil 4a of the induction heating cooker after being placed on and energized, the current path and Due to the current path formed by the heating coil 5 and the resonant capacitor 4b, the generation of the induced electromotive force or the induced current generated at both ends of the switching means 4a is suppressed by blocking the current path. There is no electrical stress applied to the switching means 4a, which is a component of the circuit 4, and it is generally composed of a semiconductor element and is less susceptible to electrical stress than the heating coil 5 and the resonant capacitor 4b, or has a high electrical potential. It is possible to reduce the electrical stress of the switching means 4a that is difficult to make stress resistant. In addition, in general, the high-frequency current value flowing through each component when the object to be heated 6 is inductively heated is determined by comparing the current of the heating coil 5 with the current of the switching means 4a. Since it becomes smaller (the smaller portion flows to the resonance capacitor 4b), if it is the insertion position of the present embodiment, the current capacity of the path opening means 9 can be reduced, and the path opening means 9 can be reduced in size and cost. Can be planned.

In the present embodiment, the path opening means 9 is an electromagnetic relay using an open / close contact. This is because, when the path opening means 9 is open, the electromotive force induced by the magnetic flux applied to the heating coil 5 from the outside of the induction heating cooker is generated at both open ends of the path opening means 9. When the path opening means 9 is constituted by a semiconductor switch in place of the switching contact, it is necessary to use a semiconductor switch having a high withstand voltage that can withstand this induced electromotive force. However, if the path opening means 9 is configured with an open / close contact, it is possible to achieve a high breakdown voltage with a relatively simple method of ensuring the distance between contacts when opening. Because it becomes.

  When the user sets the operation start of the inverter circuit 4 with the operation setting means 10, the path opening means 9 makes this current path conductive, and the inverter circuit 4 starts to operate approximately 2 seconds after the operation start is set. The time of about 2 seconds is a time with sufficient margin for the operation start setting and the timing at which the inverter circuit 4 starts to operate with respect to the operation time of the path opening means 9 and the time including the variation thereof, Therefore, the inverter circuit 4 starts to operate after the path opening means 9 is surely turned on, and before the current starts to flow to the inverter circuit 4 through the path opening means 9, the contact is made by zero current switching operation. It is closed to facilitate switching loss reduction of the path opening means 9 and ensuring the durability of the contacts.

  Next, when the user sets the operation stop of the inverter circuit 4 by the operation setting means 10, the drive means 8 stops the driving of the switching means 4a, whereby the inverter circuit 4 is stopped and the operation stop is set. After about 1 second, the path opening means 9 becomes non-conductive. The time of about 1 second is a time that has a sufficient margin with respect to the time when the path opening means 9 starts operating in the non-conductive state with respect to the time when the operation is set to stop and the inverter circuit 4 stops operating. Therefore, after the inverter circuit 4 is surely stopped, the path opening means 9 is brought into a non-conducting state, and after the path opening means 9 stops flowing in the inverter circuit 4, the contact is made by zero current switching operation. To reduce the switching loss of the path opening means 9 and to prevent arcing of the contacts, thereby ensuring durability.

  If an instantaneous power failure occurs in the commercial power supply 1 while the inverter circuit 4 is operating, the operation of the inverter circuit 4 becomes unstable after the power failure is restored. In this embodiment, the power failure detection means 12 is provided to detect a power failure. Then, the operation of the inverter circuit 4 is temporarily stopped, and after detecting that the inverter circuit 4 has recovered from a power failure, the inverter circuit 4 is operated again. In general, when an instantaneous power failure occurs, the display circuit LED, etc., which is the load, etc. are used to reduce the current consumption of the control circuit so that the device can return to the state before the power failure as much as possible when the power failure is restored. The driving of the electromagnetic relay is stopped, but the driving of the electromagnetic relay ON of the path opening means 9 of the present embodiment is not stopped. This is because, when the inverter circuit 4 is stopped, the current flowing transiently to the path opening means 9 is not interrupted, and the same operation as in the case without the path opening means 9 is inherited and each component of the inverter circuit 4 is used. The transient generation voltage and inflow current of the inverter circuit 4 are the same as when the path opening means 9 is not provided, and the transient generation voltage and inflow in each component of the inverter circuit 4 due to the difference in timing when the path opening means 9 becomes non-conductive. The current change is eliminated, the transient operation when the inverter circuit 4 is stopped is always constant, and the power failure is usually recovered immediately. Therefore, the path opening means 4 is unnecessary from the start to the recovery of the power failure. When conduction / non-conduction is prevented and the path opening means 4 is a switching contact type, the number of switching operations is suppressed, and the durability and reliability of the contacts are easily ensured.

  Before starting operation or when power is not supplied to the electromagnetic relay for a long time (for example, when the power switch is turned off), the contact of the electromagnetic relay is open and the inverter circuit 4 is cut off. The influence of the magnetic flux can be suppressed.

Further, in this embodiment, the operation of the inverter circuit 4 becomes unstable, and when the abnormality detection means 13 that monitors the voltage across the switching means 4a detects an abnormal increase in the voltage across the switching means 4a, The operation is stopped and a permanent failure of the inverter circuit 4 is prevented. When the inverter circuit 4a is stopped, the current flowing transiently in the path opening means 9 is not interrupted, and the same operation as in the case without the path opening means 9 is inherited and the components in the inverter circuit 4 are made transient. The generated voltage and inflow current are equivalent to those when there is no path opening means 9, and the transient generated voltage and inflow current change in each component of the inverter circuit 4 due to the difference in timing when the path opening means 9 becomes non-conductive. , The transient operation when the inverter circuit 4 is stopped is always constant, and the operation of the inverter circuit 4 is often eliminated by temporarily stopping the operation of the inverter circuit 4. Instability usually recovers immediately, so unnecessary conduction / non-conduction of the path opening means 9 is prevented from the start to the recovery of the instability. Achieving the number of suppression, to facilitate durability of the contact, to secure reliability.

  Furthermore, in the present embodiment, when the contact abnormality detection means 14 detects an abnormality in the contact state, such as non-conduction when the path opening means 9 should be conductive, or conduction when the path opening means 9 should be non-conductive, the inverter circuit 4 Is disabled when the path opening means 9 should be conductive, avoiding a secondary failure caused by an incomplete configuration of the inverter circuit 4, and the path opening means 9 Electrical stress on the components of the inverter circuit 4 due to leakage magnetic flux from other induction heating type appliances, etc. being applied to the heating coil 5 of the induction heating cooker while remaining conductive when it should be non-conductive The notification means 11 can notify the user that there is a possibility of application, and prompt the user to take measures.

  In this embodiment, the path opening means 9 is configured to make the high potential end of the switching means 4a conductive / non-conductive. However, the other end of the heating coil 5 is made conductive / nonconductive, The heating coil 5 itself that receives a leakage magnetic flux from a heating device or the like may be separated from the inverter circuit 4. In this case, it is possible to prevent an excessive electrical stress from being applied to all the components of the inverter circuit 4. . However, when the inverter circuit 4 is operating, the current of the heating coil 5 flows through the path opening means 9, so that the path is higher than when the high potential end of the switching means 4a is turned on / off. The opening means 9 needs to increase the allowable current capacity.

  Further, if the path opening means 9 is inserted at one end of the resonance capacitor 4b, the induced electromotive force due to the LC resonance generated in the current path between the heating coil 5 and the resonance capacitor 4b cannot be generated. Since the electromotive force is not applied and the application of electrical stress to the switching means 4a having relatively high resistance to electrical stress can be prevented, the effect of the present invention can be obtained.

  Furthermore, although the configuration of the inverter circuit 4 of the present embodiment has been described with the switching means 4a and the resonant capacitor 4b being each one voltage resonant inverter, the inverter having a configuration having a plurality of switching means 4a and resonant capacitors 4b, For example, a current path including the heating coil 5 is provided in any inverter configuration such as a half-bridge type single-end push-pull inverter as shown in FIG. 2, a full-bridge type inverter as shown in FIG. Needless to say, the effect is effective.

  In addition, although the abnormality detection means 13 is made to detect by the abnormal rise of the both-ends voltage of the switching means 4a, you may detect with physical quantities, such as the both-ends voltage and inflow current of the component of the other inverter circuit 4, The inverter circuit 4 may be protected from an abnormal increase of the power supply voltage by a physical quantity correlated with the size of the commercial power supply 1 such as the output voltage of the smoothing circuit 3.

  Note that the control of the induction heating output to the heated body 6 may change not only the conduction time of the switching means 4a but also the driving cycle and the driving time ratio according to the configuration of the inverter circuit 4 and the like.

The induction heating device of the present invention has already been put into practical use because it can mitigate or prevent inadvertent application of electrical stress to its components when the inverter circuit is not operating due to leakage magnetic flux from an external device or the like. It can be applied not only to induction heating cookers and induction heating rice cookers, but also to heating appliances such as electric water heaters, electric irons, dishwashers, and water heaters that can be used for induction heating. It can also be applied to other electrical equipment using a coil or a transformer, a microwave oven, a refrigerator, a washing machine, and the like.

The block diagram of the induction heating apparatus in Embodiment 1 of this invention Inverter circuit diagram of configuration example 1 of the induction heating apparatus in the first embodiment of the present invention The inverter circuit diagram of the structural example 2 of the induction heating apparatus in Embodiment 1 of this invention Inverter circuit diagram of configuration example 3 of the induction heating apparatus in the first embodiment of the present invention

Explanation of symbols

1 Commercial power supply (AC power supply)
4 Inverter circuit 4a Switching means 4b Resonance capacitor 5 Heating coil 6 Pan (Heating object)
9 Route opening means 10 Operation setting means 11 Notification means 12 Power failure detection means 13 Abnormality detection means 14 Contact abnormality detection means

Claims (11)

A direct current obtained by rectifying and smoothing an AC power source including a heating coil, a resonance capacitor, and switching means is converted into a high frequency alternating current by driving the switching means, and the heating coil and the resonance capacitor, or the heating coil and the switching Or an inverter circuit that inductively heats the object to be heated by generating a high-frequency current in a current path including the heating coil, the resonance capacitor, and the switching means, and the current path when the inverter circuit is not operating An induction heating apparatus having a path opening means for making at least one of the constituent elements nonconductive. The induction heating apparatus according to claim 1, wherein the path opening means makes one end of the heating coil nonconductive. The induction heating apparatus according to claim 1, wherein the path opening means makes one end of the switching means nonconductive. The induction heating apparatus according to claim 1, wherein the path opening means makes one end of the resonance capacitor non-conductive. The induction heating apparatus according to any one of claims 1 to 4, wherein the path opening means includes an open / close contact. An operation setting means for setting the operation of the inverter circuit, and when the operation setting is set by the operation setting means, the path opening means conducts the path and the operation of the inverter circuit starts after a first predetermined time elapses; The induction heating apparatus according to any one of claims 1 to 5, which is configured. The induction heating apparatus according to claim 6, wherein when the operation setting means is set to stop, the inverter circuit is stopped and the path opening means makes the path non-conductive after the second predetermined time has elapsed. The induction heating device according to claim 6 or 7, wherein the path opening means maintains continuity while the operation setting means is set to operate the inverter circuit. 9. The apparatus according to claim 8, further comprising a power failure detection means for detecting a power failure of the AC power supply, wherein the path opening means maintains continuity while the power failure detection means detects a power failure and stops the inverter circuit. Induction heating device. 9. The apparatus according to claim 8, further comprising an abnormality detection unit configured to detect an operation abnormality of the inverter circuit, wherein when the abnormality detection unit detects an abnormality, the operation of the inverter circuit is stopped and the path opening unit maintains conduction. Induction heating device. Contact abnormality detecting means for detecting abnormality of the contact of the path opening means, and notification means for informing the operation setting state of the inverter circuit, and when the contact abnormality means detects abnormality of the contact, the inverter circuit is The induction heating apparatus according to claim 5, wherein the induction heating device is configured to make the operation incapable and notify the abnormality of the contact of the path opening means or the inability to operate the inverter circuit.

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