JP2013149470A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive induction heating apparatus capable of performing both of a method of uniformly heating an object and a method of convection-generating heating an object.SOLUTION: The induction heating apparatus comprises: plural first heating coil 55 and second heating coil 57; a first resonance capacitor 56 and a second resonance capacitor 58 forming the heating coils and resonance circuits; switching means that controls the conduction of the heating coils; a single inverter circuit 43 that supplies a high frequency current to plural heating coils; and control means 59 that outputs a drive signal to the inverter circuit and switching means to control open/close of the operation of the inverter circuit and the switching means. A single inverter circuit 43 controls the high frequency current to be supplied to plural heating coils at a time and controls a first relay 61 and a second relay 62 to turn on and off to control the conduction/non conduction.

Description

  The present invention relates to an apparatus using induction heating such as an induction heating cooker.

  Conventionally, in this type of induction heating apparatus, there is one in which one heating region is constituted by a plurality of heating coils arranged in a plane, and each heating coil is energized with a time difference provided sequentially (see, for example, Patent Document 1). ).

  In the induction heating apparatus described in Patent Document 1, since a specific place is not heated by changing the coil that is sequentially energized, the temperature distribution of the object to be heated is averaged so that a doughnut-shaped heating unit is not generated. can do.

  In addition, in the induction heating apparatus constituted by a central coil and four peripheral coils in which one heating region is arranged in a plane, two peripheral coils are turned on, and the other two peripheral coils are turned off. There is also a control that repeats the step A in which A and two peripheral coils that have been turned on are turned off and the other two peripheral coils that have been turned off are turned on (for example, patents). Reference 2).

  Since the induction heating apparatus described in Patent Document 2 alternately heats a pan whose peripheral coil is an object to be heated, predetermined convection is formed in cooking utensils such as moisture contained in the pan. Is done. Thereby, the cooking utensil material in a pan is heated uniformly, and it can suppress that a part of cooking utensil material is overheated, and can prevent scorching.

JP-A-63-291387 International Publication No. 2010/101202

  However, in the conventional configuration, an inverter circuit for controlling the energization state of each of the plurality of heating coils is required, and the number of parts of the circuit is large, resulting in an expensive induction heating apparatus.

  In Patent Document 1, switching elements (inverter circuits) are connected to a plurality of heating coils, and the energized state is controlled by operating each switching element with a time difference sequentially. It can be seen that the same number of switching elements (inverter circuits) are required.

  Similarly, in Patent Document 2, an inverter circuit is provided for each of the plurality of heating coils, so that the number of circuit parts is large and the induction heating apparatus is expensive.

Moreover, in patent document 1, although only one switching element (inverter circuit) is connected with respect to several heating coils, a common relay is provided between each heating coil and a power supply, and a connection with a power supply is switched sequentially. Thereby, the energization state to each heating coil is controllable. However, in the invention of Patent Document 1, since the heating coil to be energized is sequentially switched by a common relay having only one contact, high-frequency current cannot be supplied to all of the plurality of heating coils at the same time. Moreover, a high frequency current cannot be simultaneously supplied to the plurality of heating coils selected based on the placement state of the object to be heated and the heating mode. When supplying high-frequency current to multiple heating coils simultaneously, rather than supplying high-frequency current to a single heating coil, the heat generated by the loss generated in the heating coil is dispersed to lower the temperature of the heating coil and restrain it to the heat-resistant temperature. Instead, high power can be supplied to the object to be heated. That is, in the invention of Patent Document 1, the object to be heated cannot be heated with high power.

  The present invention solves the above-described conventional problems, and can inexpensively heat an object to be heated or convect a liquid contained in a container of the object to be heated, and can be an inexpensive induction heating apparatus that does not increase an inverter circuit. The purpose is to provide.

  In order to solve the conventional problems, an induction heating apparatus of the present invention includes a plurality of heating coils for induction heating a single object to be heated, a resonance capacitor that forms a resonance circuit with the heating coil, and the heating coil. Open / close means for controlling the energization state, a single inverter circuit for supplying high-frequency current to the plurality of heating coils, a drive signal to the inverter circuit and the open / close means to output the operation of the inverter circuit and the open / close Control means for controlling the open / close state of the means, and the plurality of heating coils are configured so that a resonance circuit is formed by the resonance capacitor and the energization state of the heating coil can be controlled by the open / close means. The heating coil is configured by controlling the operation of the inverter circuit by the control means. A state in which a high-frequency current flows through all of the plurality of heating coils by changing the open / close state of the opening / closing means by the control means, and at least one of the plurality of heating coils is a high-frequency current. It is possible to switch between the state of not flowing.

  Since the induction heating device of the present invention can control the current flowing in a plurality of heating coils with a single inverter circuit, the number of components required for the inverter circuit is reduced, and an inexpensive induction heating device is realized. Can do.

  In addition, by controlling on / off of the opening / closing means, all the heating coils can be energized to heat the object to be heated with high power, and some of the heating coils can be de-energized to be the object to be heated. Since the convection can be generated in the contents of the container, for example, by applying the induction heating device of the present invention to the induction heating cooker, the cooking performance can be accelerated by adding heat and taste to the cooked food. Can be improved.

Circuit diagram of induction heating apparatus according to Embodiment 1 of the present invention 1st arrangement drawing of two heating coils of induction heating device concerning Embodiment 1 of the present invention Circuit diagram of induction heating device when two relays of induction heating device according to Embodiment 1 of the present invention are turned on The figure which shows a heating part when two relays of the induction heating apparatus which concern on Embodiment 1 of this invention are turned ON. Circuit diagram of induction heating apparatus when one relay of induction heating apparatus according to Embodiment 1 of the present invention is turned on The figure which shows a heating part when one relay of the induction heating apparatus which concerns on Embodiment 1 of this invention is turned ON. 2nd arrangement drawing of two heating coils of induction heating device concerning Embodiment 1 of the present invention. Arrangement of three heating coils of induction heating apparatus according to Embodiment 1 of the present invention Transition diagram of on / off control of two relays of induction heating apparatus according to Embodiment 2 of the present invention The figure which shows the heating part in each mode of the induction heating apparatus which concerns on Embodiment 2 of this invention. The figure which shows the resonance characteristic by the heating coil and resonance capacitor of the induction heating apparatus which concerns on Embodiment 3 of this invention Circuit diagram of induction heating apparatus according to Embodiment 4 of the present invention Arrangement of four heating coils of induction heating apparatus according to Embodiment 5 of the present invention Circuit diagram of induction heating apparatus according to Embodiment 5 of the present invention The figure which shows the heating part in each mode of the induction heating apparatus which concerns on Embodiment 5 of this invention. Circuit diagram of induction heating apparatus according to Embodiment 6 of the present invention The figure which shows the heating part in each mode of the induction heating apparatus which concerns on Embodiment 6 of this invention. Circuit diagram of induction heating apparatus according to Embodiment 7 of the present invention The figure which shows the heating part in each mode in the 1st connection state of the induction heating apparatus which concerns on Embodiment 7 of this invention. The figure which shows the heating part in each mode in the 2nd connection state of the induction heating apparatus which concerns on Embodiment 7 of this invention. The figure which shows the heating part in each mode in the 3rd connection state of the induction heating apparatus which concerns on Embodiment 7 of this invention. Arrangement | positioning drawing of the 2nd heating coil of the induction heating apparatus which concerns on Embodiment 7 of this invention.

  According to a first aspect of the present invention, there are provided a plurality of heating coils for induction heating a single object to be heated, a resonance capacitor that forms a resonance circuit with the heating coil, an opening / closing means for controlling an energization state of the heating coil, A single inverter circuit for supplying a high frequency current to the heating coil, and a control means for controlling the operation of the inverter circuit and the open / close state of the open / close means by outputting a drive signal to the inverter circuit and the open / close means. The plurality of heating coils are configured to be connected to the single inverter circuit so that a resonance circuit is formed by the resonance capacitor and the energization state of the heating coil can be controlled by the opening / closing means, By controlling the operation of the inverter circuit by the control means, the high-frequency current flowing through the heating coil is changed, By controlling the open / close state of the open / close means by the control means, it is possible to switch between a state in which a high-frequency current flows through all of the plurality of heating coils and a state in which at least one of the plurality of heating coils does not flow a high-frequency current. To do.

  As a result, the current flowing through the plurality of heating coils can be controlled by a single inverter circuit, so that the number of components required for the inverter circuit can be reduced and an inexpensive induction heating apparatus can be realized.

  In addition, by controlling on / off of the opening / closing means, all the heating coils can be energized to heat the object to be heated with high power, and some of the heating coils can be de-energized to be the object to be heated. Since the convection can be generated in the contents of the container, for example, by applying the induction heating device of the present invention to the induction heating cooker, the cooking performance can be accelerated by adding heat and taste to the cooked food. Can be improved.

  In the second invention, in particular, in the induction heating apparatus of the first invention, a heating coil that does not pass a high-frequency current is switched at regular intervals.

This allows the convection direction of the liquid to be switched when the content of the object to be heated is a liquid. It is possible to improve the cooking performance by heating the object to be heated with a heating pattern suitable for the above.

  In particular, the third invention has a plurality of resonance circuits connected to the inverter circuit in the induction heating device of the first or second invention, and substantially matches the resonance characteristics of the respective resonance circuits.

  Thereby, when the heating coil to be energized is selected depending on the cooking content, the size of the object to be heated, the mounting state, etc., the operating frequency of the inverter circuit can be made constant even if the number of energizing heating coils is changed. Even if heating is performed simultaneously with a plurality of induction heating devices that are close to each other in the heating area, there is no difference in the operating frequency, so that it is possible to realize an induction heating device that does not generate a buzzing interference sound and does not make the user uncomfortable. .

  According to a fourth invention, in particular, in the induction heating device of the first or second invention, a single resonance circuit is connected to the inverter circuit.

  As a result, the number of resonant capacitors necessary for forming the resonant circuit can be minimized, and an inexpensive induction heating device can be realized.

  In the fifth aspect of the invention, in particular, in the induction heating device according to any one of the first to fourth aspects, a plurality of heating coils having different heating parts of the object to be heated are electrically connected to conduct / non-conduct high-frequency current. These periods are matched.

  As a result, the number of resonance circuits is less than the number of heating coils and the number of inverter circuits is one even in a configuration in which a plurality of heating coils are distributed and heated in a uniform manner. The induction heating device can be realized with a small number of parts that constitute the inverter circuit and at a low cost and with a small volume.

  Moreover, electric power can be simultaneously supplied by connecting the heating coil with the same increase / decrease timing of the electric current which flows into a heating coil in the same resonance circuit. The current sensors can be unified and made inexpensive, and the controllability of power can be improved.

  The sixth invention is particularly point-symmetric in the induction heating apparatus according to any one of the first to fifth inventions, wherein a plurality of heating coils are arranged so as to be point-symmetric from the center of the heating region of the object to be heated. Are connected to the same resonance circuit.

  Thereby, since the heating coil located farthest diagonally is driven at the same time, it is possible to generate a slow convection that spreads over the entire pan.

  According to a seventh aspect of the invention, in particular, in the induction heating apparatus according to any one of the first to fifth aspects, the plurality of heating coils are arranged so as to be symmetrical with respect to the center of the heating region of the object to be heated, and are adjacent to each other. The heating coil is connected to the same resonance circuit.

  Thereby, the heating region and the non-heating region of the object to be heated can be clearly separated, and a large convection can be generated in the liquid in the object to be heated, so that, for example, the taste can be quickly infused into the food.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a circuit diagram of the induction heating apparatus according to the first embodiment of the present invention, and shows an example of a method for connecting an inverter circuit, a plurality of heating coils, and a resonant capacitor.

  In FIG. 1, a power source supplied from an outlet or the like is an AC power source 41, and a diode bridge 46 is connected to convert the AC power source 41 into a DC power source. A choke coil 47 and a capacitor 48 are connected to the output terminal of the diode bridge 46 in order to smooth the DC power output from the diode bridge 46 and not to propagate electromagnetic noise generated from the induction heating device to the AC power supply 41. Has been.

  The diode bridge 46, the choke coil 47, and the capacitor 48 constitute a rectifier 42 that rectifies the power supplied from the AC power supply 41.

  On the output side of the capacitor 48, a first switching element 51 having a reverse conducting diode 52 connected in parallel and a second switching element 53 having a reverse conducting diode 54 connected in parallel are electrically connected in series. The inverter circuit 43 is connected.

  One end of the first resonance circuit 44 including the first heating coil 55 and the first resonance capacitor 56 is / is not electrically connected to the connection point between the first switching element 51 and the second switching element 53. As an opening / closing means for switching between, one end of the second resonance circuit 45 including the first relay 61, the second heating coil 57, and the second resonance capacitor 58 is opened / closed for switching between connection / non-connection. As a means, a second relay 62 is connected.

  The other terminal of the first resonance circuit 44 and the other terminal of the second resonance circuit 45 are connected to the negative potential side of the DC voltage. In addition, the snubber capacitor 60 is electrically connected in parallel with the second switching element 53 in order to reduce switching loss caused by the switching operation of the first switching element 51 and the second switching element 53.

  Further, by having a control means 59 for driving and controlling the first switching element 51, the second switching element 53, the first relay 61, and the second relay 62, the circuit of the induction heating apparatus of the present embodiment can be provided. Form.

  About the induction heating apparatus formed as mentioned above, the operation | movement and an effect | action are demonstrated below.

  Inverter circuit 43 of the induction heating device shown in this embodiment controls the operating frequency of first switching element 51 and second switching element 53, the ratio of conduction (on) time to non-conduction (off) time, and the like. Thus, the high-frequency current flowing in the first resonance circuit 44 and the high-frequency current flowing in the second resonance circuit 45 are changed, and the power supplied from the first heating coil 55 and the second heating coil 57 to the object to be heated. Can be adjusted.

  The first switching element 51 and the second switching element 53 are exclusively turned on so that the power supply is not short-circuited.

  Moreover, since the 1st heating coil 55 and the 1st relay 61, the 2nd heating coil 57, and the 2nd relay 62 are each connected in series, by making a relay into a non-conduction state, a non-conduction state It is possible to prevent high-frequency current from flowing through the heating coil connected in series with the relay.

FIG. 2 shows an example of the arrangement of the first heating coil 55 and the second heating coil 57 of the two heating coils of the induction heating device according to the first embodiment of the present invention. The first heating coil 55 and the second heating coil 57 are arranged concentrically.

  In the induction heating apparatus of the present embodiment, since the single object to be heated is heated by the first heating coil 55 and the second heating coil 57, the heating region 11 has the first heating coil 55 and the second heating coil 55. The heating coil 57 is combined.

  FIG. 3 is a circuit diagram when both the first relay 61 and the second relay 62 of the induction heating device according to the first embodiment of the present invention are in a conductive state. In this state, the inverter circuit 43 is switched on. By operating, the supply region of the high-frequency current becomes the entire surface of the heating region 11 as shown by the oblique lines in FIG. FIG. 4 is a diagram showing a heating unit when two relays of the induction heating apparatus according to the first embodiment of the present invention are turned on.

  On the other hand, FIG. 5 is a circuit diagram when the first relay 61 of the induction heating device according to the first embodiment of the present invention is in a conductive state and the second relay 62 is in a non-conductive state. By operating the inverter circuit 43 in this state, the supply region of the high-frequency current is only the central portion of the heating region 11 as shown by the oblique lines in FIG. Here, if the relay to be in a conductive state and the relay to be in a non-conductive state are switched, it is natural that the supply region of the high-frequency current is also switched. FIG. 6 is a diagram showing a heating unit when one relay of the induction heating apparatus according to the first embodiment of the present invention is turned on.

  In the induction heating apparatus according to the present embodiment, the object to be heated is generally heated from the entire surface of the heating region 11 by turning on both the first relay 61 and the second relay 62. As a result, the high-frequency current flowing through the heating coil can be distributed to the first heating coil 55 and the second heating coil 57, so that the heat generation from the heating coil caused by the high-frequency current flowing can be suppressed and the low-voltage resonant capacitor. It is possible to heat an object to be heated with a large amount of power even when using low-spec parts, such as the use of the above. Further, by increasing the heating area, the object to be heated can be heated as uniformly as possible.

  However, the object to be heated must be placed on all the heating coils, for example, the size of the object to be heated is smaller than the heating area 11 or the object to be heated is placed out of the heating area 11. For example, the relay connected in series with the heating coil on which the object to be heated is not placed is in a non-conductive state, so that high-frequency current that does not contribute to heating of the object to be heated does not flow and heating efficiency is increased. Can be made. Further, it is possible to reduce the leakage magnetic field that propagates to the surroundings without contributing to the heating of the object to be heated.

  Further, since it is difficult for a magnetic field to propagate around the heating region 11, even when there are a plurality of heating regions 11 close to each other, a high-frequency current that flows through a heating coil that heats an object to be heated placed in another heating region 11 Therefore, an induction heating apparatus that does not make the user uncomfortable can be realized.

  Furthermore, since there is only one inverter circuit that supplies high-frequency current to the two heating coils, it can be realized at low cost by not increasing the inverter circuit 43. In addition, a compact configuration can be realized without increasing the volume of the inverter circuit.

  Furthermore, the arrangement of the heating coils is not limited to a concentric circle. For example, the same effect can be obtained by arranging the heating coils side by side in the heating region 11 as shown in FIG. It is a 2nd arrangement drawing of two heating coils of the induction heating apparatus which concerns on the 1st Embodiment of this invention.

Further, the number of resonance circuits and the number of heating coils may be any combination, such as three resonance circuits and three heating coils as shown in FIG. FIG. 8 is a layout diagram of three heating coils of the induction heating apparatus according to the first embodiment of the present invention.

  In this embodiment, a relay is used as the opening / closing means. However, the present invention is not limited to this as long as energization control can be performed.

(Embodiment 2)
FIG. 9 is a transition diagram of on / off control of the two relays of the induction heating device according to the second embodiment of the present invention, and shows an example of a switching sequence of conduction / non-conduction of a plurality of opening / closing means. .

  FIG. 10 is a diagram showing a heating unit in each mode of the induction heating apparatus according to the second embodiment of the present invention, and when a plurality of opening / closing means are controlled in the sequence shown in FIG. The heatable region in each mode is shown.

  Here, in this embodiment, only parts different from the above-described embodiment will be described, and description of the same parts as those in the above-described embodiment will be omitted.

  In the induction heating device of the present embodiment, the first relay 61 and the second relay 62 are connected in series with the first heating coil 55 and the second heating coil 57, respectively. By turning off the heating coil connected in series with the relay in the (off) state, it is possible to prevent high-frequency current from flowing through the heating coil regardless of the operation of the inverter circuit 43. It is possible to prevent power from being supplied from the heating coil to the object to be heated.

  In the induction heating device of the present embodiment, the first relay 61 and the second relay 62 are alternately turned on and off, for example, when the object to be heated is a pan, the moisture contained in the pan A predetermined convection is formed in the cooking utensil material. Thereby, the cooking utensil material in a pan is heated uniformly, and it can suppress that a part of cooking utensil material is overheated, and can prevent scorching.

  In addition, since the convection direction can be changed periodically, it is possible to prevent the noodles from being entangled when boiling water.

  Furthermore, by changing the convection direction by periodically changing the heating part of the object to be heated, for example, the conventional induction heating cooking in which the generated lye or the like accumulates in a certain spot area and becomes easy to blow down. The problem of the vessel can be improved and it can be made difficult to blow.

  In addition, by heating only a part of the pan, after the heated liquid such as water has risen to the upper part of the liquid, the liquid smoothly flows to the unheated part, and the flow rate of the liquid is increased. It is possible to cook in a short time by accelerating the transmission of heat to the ingredients and the soaking of taste.

  Further, even when the heating mode is set to be switched, the heating object is smaller than the heating region 11 and there is a heating coil on which the heating object is hardly placed. By continuing to turn off the relay connected to the coil, the leakage magnetic field can be reduced, the heating efficiency can be improved, and the occurrence of beat interference noise can be suppressed.

  In the present embodiment, the example in which a total of two relays of the first relay 61 and the second relay 62 are used has been described, but the relays to be turned off are sequentially switched using three or more relays. May be. Further, both the first relay 61 and the second relay 62 may be turned on in the sequence.

  Furthermore, the induction heating device of the present embodiment is configured with the number of inverter circuits smaller than the number of heating coils, and it is sufficient if the heating area 11 can be heated entirely and convectively heated. The on-time Tb is not specified.

(Embodiment 3)
FIG. 11 is a diagram showing resonance characteristics by the heating coil and the resonance capacitor of the induction heating device according to the third embodiment of the present invention, which can be supplied to the operating frequency of the inverter circuit of the induction heating device and the object to be heated. It shows the relationship of power.

  Here, in this embodiment, only parts different from the above-described embodiment will be described, and description of the same parts as those in the above-described embodiment will be omitted.

  When adjusting the power supplied to the object to be heated from the first heating coil 55 and / or the second heating coil 57 by controlling the operating frequency of the inverter circuit 43, under a constant applied voltage to the inverter circuit 43, When the inverter circuit 43 is operated at the resonance frequency of the resonance circuit, the resonance (power) characteristic is such that the power supplied to the object to be heated is maximized.

  In FIG. 11, the power characteristic 71 of the first resonance circuit is a power characteristic supplied from the first heating coil 55 included in the first resonance circuit 44 to the object to be heated. The power characteristic 72 is a power characteristic supplied to the object to be heated from the second heating coil 57 included in the second resonance circuit 45.

  In the induction heating device of the present embodiment, the resonance characteristics (for example, the resonance frequency) of the first resonance circuit 44 and the resonance characteristics of the second resonance circuit 45 are substantially matched. The power characteristic 71 of the first resonance circuit indicating the characteristic and the power characteristic 72 of the second resonance circuit indicating the power characteristic in the second resonance circuit 45 overlap each other.

  An operation region in FIG. 11 indicates an operation frequency range of the inverter circuit 43. When the first resonance circuit 44 and the second resonance circuit 45 are operated by the inverter circuit 43, the operation frequency of the inverter circuit 43 is higher than the resonance frequency of the first resonance circuit 44 or the second resonance circuit 45. Then, the current is delayed in phase with respect to the voltage applied to the first resonance circuit 44 and the second resonance circuit 45.

  On the other hand, when the operating frequency of the inverter circuit 43 is lower than the resonance frequency of the first resonance circuit 44 or the second resonance circuit 45, the voltage applied to the first resonance circuit 44 or the second resonance circuit 45 is increased. On the other hand, the current advances and becomes a phase.

  When the power supply to the inverter circuit 43 is a voltage source, the operating frequency of the inverter circuit 43 is set higher than the resonance frequency of the first resonance circuit 44 and the second resonance circuit 45, and the resonance current is set in a delayed phase. The current flowing in the first switching element 51 and the second switching element 53 when the first switching element 51 and the second switching element 53 transition from on to off due to the connection of the snubber capacitor 60. By flowing through the snubber capacitor 60, voltage changes applied to the first switching element 51 and the second switching element 53 become gentle, and the first switching element 51 and the second switching element 53 are turned off. Switching loss that occurs sometimes can be suppressed. From this viewpoint, it is desirable that the operating frequency of the inverter circuit 43 be higher than the resonant frequency of the resonant circuit.

In addition, since the induction heating device of the present embodiment shares the inverter circuit 43 and connects the two resonance circuits of the first resonance circuit 44 and the second resonance circuit 45 in parallel, the inverter circuit 43 The sum of currents flowing through the two resonance circuits flows through the first switching element 51 and the second switching element 53 that constitute the circuit.

  When a single object to be heated is heated by the first heating coil 55 and the second heating coil 57, for example, if the rated power that can be supplied from the heating region 11 to the object to be heated is 3 kW, the size of the object to be heated is small. When the object to be heated placed only on one heating coil is heated, for example, when it is placed out of the center of the heating region 11, the power that can be supplied is assumed to be constant for the circuit components. It will be about 1.5kW.

  By substantially matching the resonance characteristics, the operating frequency when a heated object of a size larger than the heating area 11 is placed without shifting from the heating area 11 and supplying 3 kW of power is reduced, and the size of the heated object is small. It is possible to match the operating frequency when power is supplied by 1.5 kW by being placed off the center of the heating region 11.

  It is necessary to heat a plurality of objects to be heated close to each other. For example, in an induction heating cooker having a plurality of heating regions, the frequency of the high-frequency current that flows through the heating coil to heat each object to be heated is different. It is desirable that the operating frequencies be matched because a beat interference sound accompanying the frequency difference is generated.

  In the induction heating apparatus of the present embodiment, the operating frequency with the supplied power according to the placement condition of the object to be heated can be matched, so that it is possible to realize an induction heating apparatus that does not generate beat interference noise.

  In addition, these effects can be realized by heating one object to be heated with a plurality of heating coils and electrically disconnecting the heating coil that does not contribute to heating of the object to be heated with a relay.

  It should be noted that control below the rated power at the same frequency becomes possible by using duty control that controls the ratio of the on-time and off-time of the switching element below the rated power.

(Embodiment 4)
FIG. 12 is a circuit diagram of an induction heating apparatus according to the fourth embodiment of the present invention, and shows an example of a method for connecting an inverter circuit, a plurality of heating coils, and a resonant capacitor.

  Here, in this embodiment, only parts different from the above-described embodiment will be described, and description of the same parts as those in the above-described embodiment will be omitted.

  In FIG. 12, only one first resonance capacitor 56 is used to form the first resonance circuit 44 with the first heating coil 55 and the second heating coil 57. Thereby, since it is not necessary to use the same number of resonant capacitors as the number of heating coils, the induction heating device can be realized at low cost.

  Further, in the present embodiment, only one circuit for detecting the voltage of the first resonance capacitor 56 may be used for the purpose of grasping the presence / absence of the object to be heated and for preventing the breakdown voltage breakdown of the first resonance capacitor 56. Therefore, the induction heating device can be configured at a lower cost.

  Note that the threshold level for judging whether or not the object to be heated is placed from the voltage generated in the first resonance capacitor 56 may be changed according to the ON / OFF state of each relay, and by using one resonance circuit. One detection means can be controlled.

  In the circuit configuration of the present embodiment, even if the first resonance capacitor 56 is common, when only one relay is turned on, only the inductance of the heating coil connected to the relay is the first resonance circuit 44. When the two relays of the first relay 61 and the second relay 62 are both turned on, the first heating coil 55 and the second heating coil 57 are connected to each other. Since the combined inductance of the two heating coils is a factor that determines the resonance frequency of the first resonance circuit 44, the resonance frequency varies depending on the energization state of the heating coil.

  At this time, if there is not a large difference in inductance between the first heating coil 55 and the second heating coil 57, it is necessary to supply a large amount of power. The inductance when the two heating coils are both energized is the respective heating coil. Since it is smaller than a single inductance, the resonance frequency is high.

  Therefore, the resonance frequency and the inverter circuit 43 are substantially matched by matching the operating frequency of the inverter circuit 43 when only one heating coil is energized with the operating frequency of the inverter circuit 43 when both heating coils are energized. When the two heating coils that reduce the difference in operating frequency are both energized, larger power can be supplied to the object to be heated.

  In addition, the frequency of the high-frequency current supplied to the heating coil can be made substantially the same regardless of the size of the object to be heated and the mounting conditions, and the beat interference sound generated when the plurality of heating regions 11 are arranged close to each other. Can be reduced.

(Embodiment 5)
FIG. 13 is an arrangement diagram of the heating coil of the induction heating device according to the fifth embodiment of the present invention, and shows an example of a method of arranging the heating coil in a point-symmetric manner from the center of the heating region. .

  FIG. 14 is a circuit diagram of an induction heating apparatus according to Embodiment 5 of the present invention, and shows an example of a method for connecting an inverter circuit, a plurality of heating coils, and a resonant capacitor.

  FIG. 15 shows the supply state of power to the heating coil according to the operating conditions of the inverter circuit of the induction heating apparatus according to Embodiment 5 of the present invention.

  Here, in the fifth embodiment, only the parts different from the first to fourth embodiments will be described, and the description of the same parts as the first to fourth embodiments will be omitted.

  FIG. 13 heats one object to be heated using the first to fourth four first heating coils 81 to fourth heating coils 84. The four first heating coils 81 to the fourth heating coil 84 are disposed in the heating region 11 that can heat the object to be heated, and are symmetric with respect to the center point of the heating region 11. A heating coil is disposed on the surface.

  FIG. 14 shows a circuit diagram of an induction heating apparatus for heating the four first heating coils 81 to the fourth heating coil 84 shown in FIG. 1 is different from the inverter circuit shown in FIG. 1 of Embodiment 1 in that two heating coils connected in series are connected as a heating coil of a resonance circuit.

  In the fifth embodiment, the first heating coil 81 and the third heating coil 83 that are point-symmetric from the center of the heating region 11 are connected in series as the heating coil of the first resonance circuit 44. The second heating coil 82 and the fourth heating coil 84 connected in series are used as the heating coil of the second resonance circuit 45, and a high-frequency current is supplied from the same inverter circuit 43 to the heating coil.

  About the induction heating apparatus formed as mentioned above, the operation | movement and an effect | action are demonstrated below.

  As shown in FIG. 14, by connecting the heating coils so as to form a common resonance circuit with a plurality of heating coils, the number of resonance circuits composed of the heating coils and the resonance capacitors is smaller than the number of heating coils. An induction heating device can be realized.

  As a result, high-frequency current can be supplied to all the heating coils with less resonance capacitors and relays than the number of heating coils, so that an inexpensive induction heating device can be provided.

  In the induction heating apparatus according to the fifth embodiment, as shown in FIGS. 13 and 15, the heating coils that are point-symmetric from the center of the heating region are connected to the same resonance circuit. Thereby, for example, the on and off periods and ratios of the high-frequency current flowing in the second heating coil 82 and the fourth heating coil 84 are the same. The same applies to the first heating coil 81 and the third heating coil 83.

  As shown in FIG. 15, the heating coil at a point-symmetrical position from the center of the heating region 11, that is, the heating coil farthest from a certain heating coil shares an on / off period and the like, as shown in FIG. 9. Thus, by switching between mode 1 and mode 2 at regular intervals, for example, when a pan containing a cooked product containing liquid as the object to be heated is used, the convection source is distributed in a well-balanced manner, and the slow convection is panned. By generating it throughout, cooking without scorching can be performed.

  In addition, since the convection can be changed, when noodles such as pasta are boiled, the noodles are entangled without stirring the contents because the convection moves to the next convection before trying to entangle it. An induction heating device that does not occur can be realized.

  Further, as shown in FIG. 3, by turning on both the first relay 61 and the second relay 62, the heated object is simultaneously heated by all the heating coils in the heating region 11. Can be heated uniformly. Therefore, when it is better in cooking performance to uniformly heat an object to be heated such as grilled food, the first relay 61 and the second relay 62 are both turned on to perform optimum heating for cooking contents. it can.

(Embodiment 6)
FIG. 16 is a circuit diagram of an induction heating apparatus according to the sixth embodiment of the present invention, and shows an example of a method for connecting an inverter circuit, a plurality of heating coils, and a resonant capacitor.

  FIG. 17 is a diagram showing a heating unit in each mode of the induction heating apparatus according to the sixth embodiment of the present invention, and shows the state of power supply to the heating coil according to the operating conditions of the inverter circuit. .

  Here, in the sixth embodiment, only the parts different from the first to fifth embodiments will be described, and the description of the same parts as the first to fifth embodiments will be omitted.

  FIG. 16 shows an inverter circuit that heats the four first heating coils 81 to the fourth heating coil 84 shown in FIG. 13. 1 is different from the inverter circuit shown in FIG. 1 in that two heating coils connected in series are connected as a heating coil of a resonance circuit.

In the sixth embodiment, two adjacent first heating coils 81 and a fourth heating coil 84 are connected in series as the heating coil of the first resonance circuit 44, and the second heating coil 82 A high frequency current is supplied from the same inverter circuit 43 to the heating coil as a heating coil of the second resonance circuit 45 by connecting the third heating coil 83 in series.

  About the induction heating apparatus formed as mentioned above, the operation | movement and an effect | action are demonstrated below.

  As an effect of the induction heating device in the sixth embodiment, similarly to the fifth embodiment, an inexpensive induction heating device can be realized by reducing the number of resonance capacitors and relays from the number of heating coils.

  In the induction heating apparatus of the sixth embodiment, two adjacent heating coils are connected to the same resonance circuit. Thereby, for example, the on and off periods and ratios of the high-frequency current flowing in the first heating coil 81 and the fourth heating coil 84 are the same. The same applies to the second heating coil 82 and the third heating coil 83.

  As shown in FIG. 17, the two heating coils adjacent to each other share an on / off period and the like, and by switching between mode 1 and mode 2 at regular intervals as shown in FIG. If you have a pan with food containing food, you can generate a large convection with a high flow rate by providing a convection source locally. Can be accelerated.

  Further, as shown in FIG. 3, by turning on both the first relay 61 and the second relay 62, the heated object is simultaneously heated by all the heating coils in the heating region 11. Can be heated uniformly. For this reason, when the cooking performance is better when the object to be heated such as grilled food is more uniform, the first relay 61 and the second relay 62 can both be turned on to perform optimum heating for cooking contents.

(Embodiment 7)
FIG. 18 is a circuit diagram of an induction heating apparatus according to the seventh embodiment of the present invention, and shows an example of a method for connecting an inverter circuit, a plurality of heating coils, and a resonant capacitor.

  FIG. 19 shows the supply state of electric power to the heating coil according to the operating conditions of the inverter circuit of the induction heating apparatus according to the seventh embodiment of the present invention.

  Here, in the seventh embodiment, only the parts different from the first to sixth embodiments will be described, and the description of the same parts as the first to sixth embodiments will be omitted.

  FIG. 18 shows an inverter circuit connection method in the case where there are six heating coils arranged in the heating region 11. FIG. 18 shows that three resonance circuits are connected to one inverter circuit. 14 and FIG. 16 are different.

  In the seventh embodiment, the first heating coil 81 and the fourth heating coil 84 that are symmetric with respect to the center of the heating region 11 are connected in series as the heating coil of the first resonance circuit 44. What connected in series the 2nd heating coil 82 and the 5th heating coil 85 was used as the heating coil of the 2nd resonance circuit 45, and what connected the 3rd heating coil 83 and the 6th heating coil 86 in series As the third resonance circuit 91, a high-frequency current is supplied from the same inverter circuit 43 to the heating coil.

FIG. 19 shows the supply state of electric power to the heating coil when the first to sixth six first heating coils 81 to sixth heating coils 86 are used to heat one object to be heated. Is.

  By connecting in series the heating coils that are point-symmetric from the center point of the heating region 11, a total of three heating coil groups are formed, and three resonance circuits are connected by connecting a resonance capacitor to each of the three heating coil groups. Are formed and connected to one inverter circuit 43 after connecting a relay to each resonance circuit to constitute an induction heating device.

  About the induction heating apparatus formed as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The induction heating device in the seventh embodiment has three resonance circuits. Similarly, when there are three or more resonance circuits, the same effect as described in the above embodiment can be obtained by selecting the resonance circuit that is electrically connected to the inverter circuit 43 by controlling on / off of each relay. Can do.

  Further, by increasing the number of the plurality of heating coils for heating one object to be heated, it is possible to increase the number of heating places and disperse the heating part, so that the object to be heated can be heated more uniformly. .

  Furthermore, even if the number of heating coils increases, only one inverter circuit is required for the induction heating apparatus of the present embodiment, so an induction heating apparatus having high cooking performance can be realized with an inexpensive and compact configuration. .

  In addition, in this Embodiment 7, although the connection method of the inverter circuit at the time of connecting the heating coil in the position which becomes a point symmetry from the center point of the heating area | region 11 in series, and the heating condition of each mode were shown, FIG. As shown in Fig. 3, adjacent heating coils may be connected to form three resonant circuits, and the effect is the same as that described in the above embodiment, and is uniform by increasing the number of heating coils. Uniformity when heating can be improved.

  Further, as shown in FIG. 21, three adjacent heating coils may be connected in series, and the six heating coils may be heated by two resonance circuits. In short, the resonance circuit is less than the number of heating coils. This embodiment is useful in that it is possible to realize an induction heating device that combines uniform / convection control of heating distribution and controllability of power with an inexpensive circuit configuration by heating with one inverter circuit. is there.

  Furthermore, as shown in FIG. 22, even when the heating coil is disposed around the central portion of the heating region 11, the heating coil disposed at the central portion independently forms a resonance circuit, By connecting two heating coils to form one resonance circuit, the heating coil can be controlled by one inverter circuit with five heating coils as three resonance circuits.

  As described above, in the description of the first to seventh embodiments of the present invention, the inverter circuit uses two switching elements, and the first resonance circuit and the second resonance circuit are connected to the negative potential side of the rectifier circuit. However, the connection method of the inverter circuit and the resonance circuit is not limited to this. For example, a switching element that constitutes one inverter circuit, such as a full-bridge inverter circuit that uses four switching elements. Any configuration can be used as long as the high-frequency current supplied to the plurality of resonance circuits can be controlled simultaneously by the drive control.

  Moreover, although the said Embodiments 1-7 demonstrated the arrangement | positioning and connection method of up to six heating coils, and how to put electric power, as long as there are two or more heating coils, they may be whatever.

  Also, the arrangement of the heating coils is not limited to that shown in the figure, and if they are arranged point-symmetrically or line-symmetrically, the same effects as those described in the above embodiment can be obtained. Needless to say, even if there is a slight shift, the effects of the present embodiment are not greatly affected by the arrangement.

  Since the present invention can perform both of heating an object to be heated uniformly and a heating method for generating convection using an induction heating method, not only household appliances including induction heating cookers. It is useful in all induction heating apparatuses that want to appropriately change the heating balance, such as for business use and industrial use.

DESCRIPTION OF SYMBOLS 11 Heating area 41 AC power supply 42 Rectification means 43 Inverter circuit 44 1st resonance circuit 45 2nd resonance circuit 55 1st heating coil 56 1st resonance capacitor 57 2nd heating coil 58 2nd resonance capacitor 59 Control Means 60 Snubber capacitor 61 First relay 62 Second relay 71 Power characteristic of first resonance circuit 72 Power characteristic of second resonance circuit 81 First heating coil 82 Second heating coil 83 Third heating coil 84 Fourth heating coil 85 Fifth heating coil 86 Sixth heating coil 91 Third resonance circuit

Claims (7)

A plurality of heating coils for induction heating a single object to be heated, a resonance capacitor that forms a resonance circuit with the heating coil, an opening / closing means for controlling the energization state of the heating coil, and a high-frequency current in the plurality of heating coils A plurality of heating coils, and a control means for controlling the operation of the inverter circuit and the open / close state of the open / close means by outputting a drive signal to the inverter circuit and the open / close means. Is a configuration in which a resonance circuit is formed by the resonance capacitor and is connected to the single inverter circuit so that the energization state of the heating coil can be controlled by the opening / closing means, and the inverter circuit by the control means By controlling the operation, the high-frequency current flowing through the heating coil is changed, and the control means An induction heating apparatus capable of switching between a state in which a high-frequency current flows through all of the plurality of heating coils and a state in which at least one of the plurality of heating coils does not flow a high-frequency current by controlling the open / close state of the opening / closing means. .   The induction heating device according to claim 1, wherein a heating coil that does not pass a high-frequency current is switched at a constant interval. The induction heating apparatus according to claim 1, wherein a plurality of resonance circuits connected to the inverter circuit are provided, and the resonance characteristics of the respective resonance circuits are substantially matched. The induction heating apparatus according to claim 1 or 2, wherein a single resonance circuit is connected to the inverter circuit. The induction heating apparatus according to any one of claims 1 to 4, wherein a plurality of heating coils having different heating portions of an object to be heated are electrically connected to match the conduction / non-conduction period of the high-frequency current. The plurality of heating coils are arranged so as to be point-symmetric from the center of the heating region of the object to be heated, and the heating coils positioned symmetrically are connected to the same resonance circuit. The induction heating device described in 1. The plurality of heating coils are arranged so as to be symmetrical with respect to the center of the heating region of the object to be heated, and adjacent heating coils are connected to the same resonance circuit. Induction heating device.

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