Induction heating device and program for induction heating device

Abstract

To provide an induction heating device capable of accurately measuring electric power supplied to each of a plurality of objects to be heated.SOLUTION: The inverter device 2 includes a plurality of group-specific half-bridge circuits X each connected to one heating coil group 1, and a common half-bridge circuit Y connected to the plurality of heating coil groups 1 and constituting a full-bridge circuit together with the group-specific half-bridge circuits X. An inverter control unit 33 configured to cause the inverter device 2 to execute a power calculation mode in which some group-specific half-bridge circuits X of the plurality of group-specific half-bridge circuits X and the common half-bridge circuit Y connected to the some group-specific half-bridge circuits X are driven in phase, and a power calculation unit 34 configured to calculate power supplied from the inverter device 2 to at least one heating coil group 1 on the basis of a current value detected by the current detection unit 4 in the power calculation mode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an induction heating device and a program for the induction heating device. [Background technology]

[0002] Conventionally, there have been induction heating devices equipped with multiple inverter circuits so that multiple objects to be heated can be induction-heated simultaneously. For example, Patent Document 1 describes an induction heating device that has two full-bridge inverter circuits configured by combining two auxiliary half-bridge circuits and one reference half-bridge circuit, and can heat multiple objects to be heated at two different output levels.

[0003] This induction heating device has a current sensor in each heating coil connected to the inverter device, and is configured to be able to detect the power supplied from each inverter circuit to each object to be heated via the heating coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6881958 Summary of the Invention [Problem to be solved by the invention]

[0005] The induction heating device of Patent Document 1 has a current sensor for each heating coil, which requires a large number of parts and increases manufacturing costs.

[0006] Therefore, for example, it is conceivable to stop driving one of the two auxiliary half-bridge circuits in this induction heating device, measure the current supplied from the power supply to the inverter device, and regard this current value as the current output to one heated object from a full-bridge inverter circuit consisting of the other auxiliary half-bridge circuit and a reference half-bridge circuit.In this case, by switching the auxiliary half-bridge circuit that is stopped, it is conceivable that it will be possible to measure the power supplied to multiple heated objects with one current sensor.

[0007] However, in reality, even if one auxiliary half-bridge circuit is stopped from driving, the reference half-bridge circuit connected to that auxiliary half-bridge circuit is driven in synchronization with the other auxiliary half-bridge circuit, so a potential difference occurs between the one auxiliary half-bridge circuit and the reference half-bridge circuit, causing a current to flow. Therefore, simply stopping the driving of the auxiliary half-bridge circuit does not allow accurate measurement of the power supplied to each heated object from the current supplied to the inverter device.

[0008] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide an induction heating device that can accurately measure the power supplied to each of multiple heated objects while reducing the number of parts required to measure the power supplied to the heated objects. [Means for solving the problem]

[0009] That is, the induction heating cooker of the present invention comprises a plurality of heating coil groups, each consisting of one or more heating coils, for induction heating different objects to be heated, an inverter device for supplying power to the heating coils, a current detection unit for detecting the current supplied to the inverter device, and a control device for controlling the inverter device, wherein the inverter device has a plurality of group-specific half-bridge circuits, each connected to one of the heating coil groups, and common half-bridge circuits, each connected to a plurality of the heating coil groups and forming a full bridge circuit together with the group-specific half-bridge circuits, an inverter control unit that causes the inverter device to execute a power calculation mode in which some of the plurality of group-specific half-bridge circuits and a common half-bridge circuit connected to the some of the group-specific half-bridge circuits are driven in phase, and a power calculation unit that calculates the power to be supplied from the inverter device to at least one heating coil group based on the current value detected by the current detection unit in the power calculation mode.

[0010] In an induction heating cooker configured in this manner, a plurality of full-bridge circuits are configured by a plurality of group-specific half-bridge circuits and a common half-bridge circuit, so that a plurality of objects to be heated can be heated simultaneously. In the power calculation mode, some of the group-specific half-bridge circuits and the common half-bridge circuit are driven in phase, reducing the potential difference between these circuits and the current flowing therethrough. This allows the current supplied to the inverter device to be closer to the current output from the inverter device to the other group-specific half-bridge circuits (excluding the some of the group-specific half-bridge circuits). This makes it possible to more accurately measure the power supplied to each heated object (heating coil group) based on the current supplied to the inverter device. In addition, this allows the power supplied to each of the multiple heated objects to be calculated using an ammeter that measures the current supplied to the inverter device, eliminating the need for a separate current sensor for each heated object or heating coil, thereby reducing the number of components.

[0011] In the power calculation mode, it is desirable that the potential difference between the other group-specific half-bridge circuits and the common half-bridge circuit be controlled to be zero. This allows the power supplied to the heating coil groups connected to some of the group-specific half-bridge circuits to be minimized, making it possible to more accurately measure the power supplied to each heated object (heating coil group).

[0012] The inverter control unit may cause the inverter device to execute a simultaneous heating mode in which the plurality of group-specific half-bridge circuits are driven out of phase with the common half-bridge circuit connected to the plurality of group-specific half-bridge circuits, and the power calculation mode may be executed at a predetermined timing in the simultaneous heating mode. This allows the power supplied to each heated object to be calculated at a predetermined timing (for example, at regular intervals or after a predetermined time has elapsed since the start of the simultaneous heating mode), and this can be fed back to enable more precise power adjustment.

[0013] It is desirable that the inverter control unit executes the power calculation mode while switching the part of the group-specific half-bridge circuits that are driven in phase with the common half-bridge circuit. This makes it possible to grasp the power supplied to each object even when three or more objects are heated simultaneously.

[0014] It is desirable that the inverter device has the same number of group-specific half-bridge circuits and the same number of common half-bridge circuits. This allows for a reduction in switching losses compared to when a full bridge circuit is configured by combining a plurality of group-specific half bridge circuits and one half bridge circuit.

[0015] It is preferable that the power supply device further comprises a relay circuit that is provided between the heating coil and the group-specific half-bridge circuit and switches the group-specific half-bridge circuit that is connected to each of the heating coils. This allows for a combination of heating coils that inductively heat a single object, making it possible to create a so-called anywhere type induction heating device without having to provide an inverter for each heating coil.

[0016] Furthermore, the program for an induction heating device according to the present invention is a program used in an induction heating device comprising: a plurality of heating coil groups, each consisting of one or more heating coils, for induction heating different objects to be heated; an inverter device that supplies power to the heating coils; a current detection unit that detects the current supplied to the inverter device; and a control device that controls the inverter device, wherein the inverter device has a plurality of group-specific half-bridge circuits, each connected to one of the heating coil groups, and common half-bridge circuits, each connected to a plurality of the heating coil groups, and forming a full-bridge inverter circuit together with the group-specific half-bridge circuits. The program also includes an inverter control unit that causes the inverter device to execute a power calculation mode in which some of the plurality of group-specific half-bridge circuits and the common half-bridge circuit connected to those some of the group-specific half-bridge circuits are driven in phase; and causes the control device to function as a power calculation unit that calculates the power to be supplied from the inverter device to at least one of the heating coil groups based on the current value detected by the current detection unit in the power calculation mode. According to such a program for an induction heating device, it is possible to achieve the same effects as those of the induction heating device described above. [Effects of the Invention]

[0017] According to the present invention configured in this manner, it is possible to provide an induction heating device that can accurately measure the power supplied to each of multiple heated objects while reducing the number of parts required to measure the power supplied to the heated objects. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an induction heating device according to a first embodiment. [Figure 2]FIG. 2 is a schematic diagram showing the overall configuration of the induction heating device according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram showing the configuration of a half-bridge circuit in the embodiment. [Figure 4] FIG. 3 is an explanatory diagram illustrating the operation of an inverter control unit in the embodiment. [Figure 5] 5A and 5B are explanatory diagrams illustrating operations in a simultaneous heating mode and a power measurement mode in the embodiment. [Figure 6] FIG. 4 is an explanatory diagram illustrating power calculation using a power measurement mode according to the embodiment. [Figure 7] FIG. 10 is an explanatory diagram for explaining power calculation using a power measurement mode according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an induction heating cooker according to the present invention will be described below with reference to the drawings.

[0020] [First embodiment] 1. Overview The induction heating device of this embodiment inductively heats heated objects, such as cooking utensils such as cooking pots, placed on a top plate, and is a so-called any-place type that is configured so that multiple heated objects can be placed freely anywhere on the top plate and heated.

[0021] 2.Device configuration 2-1. Overall structure Specifically, as shown in Figures 1 and 2, the induction heating device 100 includes a top plate P on which multiple objects to be heated Q are placed, multiple heating coil groups 1 that induction heat different objects to be heated Q, an inverter device 2 that supplies power to the heating coil group 1, and a control device 3 that controls the inverter device 2.

[0022] Furthermore, the induction heating device 100 is equipped with a position detection sensor (not shown) that detects the position of the object to be heated Q placed on the top plate P, a current detection unit 4 that detects the current supplied to the inverter device 2, and a voltage detection unit 5 that detects the voltage supplied to the inverter device 2 from a commercial power source.

[0023] 2-2.Top plate P As shown in FIG. 1, the top plate P has a flat surface on the front side on which an object to be heated Q, such as a cooking pot, is placed, and is a flat plate made of an electrically insulating material such as glass or ceramic.

[0024] 2-3. Heating coil group 1 As shown in Figures 1 and 2, the heating coil group 1 consists of one or more heating coils provided on the back side of the top plate P, and one heating coil group 1 is configured to inductively heat one heated object Q through the top plate P.

[0025] In this embodiment, four heating coils a to d are arranged in a row in a plan view. Here, the heating coil group 1 (a, b) refers to a heating coil group 1 consisting of two heating coils a and b. The number of heating coils is not limited to four, but may be three or more. The arrangement is also not limited to a row, and may be, for example, arranged in a two-dimensional array (vertical and horizontal matrix).

[0026] Each of the heating coils a to d is in the form of a sheet provided on a substrate, specifically formed as a printed circuit board made of photoresist or the like. Here, each of the multiple heating coils has the same shape and size, but the shape and size may be changed as appropriate. Furthermore, the heating coil may be formed by winding a litz wire.

[0027] 2-4. Inverter device 2 The inverter device 2 converts the voltage supplied from a commercial power source into high-frequency power and supplies high-frequency power to the plurality of heating coil groups 1. Here, each heating coil group 1 is configured to be supplied with power according to the heating power set by the user for each object Q to be heated.

[0028] Specifically, as shown in FIG. 2, the inverter device 2 has two group-specific half-bridge circuits X1 and X2 connected to one end of the heating coils a to d, two common half-bridge circuits Y1 and Y2 connected to the other end of the heating coils a to d, and a relay circuit 22 provided for each of the heating coils a to d and switching the group-specific half-bridge circuit X connected to each of the heating coils a to d.

[0029] 2-4-1. Half-bridge circuit X, Y The group-specific half-bridge circuits and the common half-bridge circuit Y are configured using two switching elements, such as IGBTs or MOS-FETs, as shown in Figure 3. A snubber capacitor is provided between the drain and source of each switching element to prevent these switching elements from being damaged by the large current generated by parasitic inductance when they are turned off.

[0030] Heating coils a to d are connected to AC terminals A and B provided between two switching elements in each half-bridge circuit X and Y. More specifically, one end of the heating coils a to d is connected to AC terminal A of the group-specific half-bridge circuit, and the other end of the heating coils a to d is connected to AC terminal B of the common half-bridge circuit Y.

[0031] In this way, the group-specific half-bridge circuits X and the common half-bridge circuit Y are connected via the heating coils to form a full-bridge inverter circuit 21. In this embodiment, a maximum of four full-bridge inverter circuits 21 are formed, sandwiching the four heating coils a to d.

[0032] The output voltage V from this inverter circuit 21 O is the potential V of AC terminal A of group-specific half-bridge circuit XA and the potential V at AC terminal B of the common half-bridge circuit Y B is equal to the potential difference (V O =V A -V B The potential of AC terminals A and B of each half-bridge circuit X and Y can be either E or 0, which corresponds to the power supply voltage E, depending on the operation of the switching element. O can take three values: E, 0, and -E.

[0033] 2-4-2. Relay circuit 22 As shown in FIG. 2, the relay circuit 22 of this embodiment is provided between the AC terminal A of the group-specific half-bridge circuit and one of the power supply terminals of the heating coils a to d, and switches, for example, whether the heating coil a is connected to one group-specific half-bridge circuit X1, the other group-specific half-bridge circuit X2, or not connected to any group-specific half-bridge circuit X.

[0034] In this embodiment, a relay circuit 22 is not provided between the AC terminal B of the common half-bridge circuit Y and the other power supply terminals of the heating coils a to d. In other words, it is predetermined which heating coil is connected to which common half-bridge circuit Y. In this embodiment, the heating coils a and c are connected to the common half-bridge circuit Y1, and the heating coils b and d are connected to the common half-bridge circuit Y2. A relay circuit 22 may be provided between the common half-bridge circuit Y and the heating coils a to d.

[0035] 2-5.Control equipment 3 The control device 3 physically comprises a CPU, memory, input means, etc., and functionally performs the functions of a position identification unit 31, a relay control unit 32, an inverter control unit 33, and a power calculation unit 34, as shown in Figure 2, by the CPU and its peripheral devices working together in accordance with the program stored in the memory.

[0036] 2-5-1. Position identification section 31 The position specifying unit 31 specifies the position of the object Q to be heated placed on the top plate P based on the output of a position detection sensor (for example, a position sensor such as an induction proximity coil), and outputs the position information.

[0037] 2-5-2. Relay control unit 32 The relay control unit 32 transmits a switching signal to the relay circuit 22 to switch the relay. Specifically, when the relay control unit 32 receives the position information of the object Q to be heated output by the position identification unit 31, it identifies one or more heating coils a to d located below or near the object Q based on the position information. Then, the relay control unit 32 transmits a switching signal to the relay circuit 22 so that one group-specific half-bridge circuit X is connected to the identified one or more heating coils a to d. The one or more heating coils connected to one group-specific half-bridge circuit X in this way are collectively referred to as the heating coil group 1 described above.

[0038] When two or more objects Q to be heated are placed on the top plate P, the relay control unit 32 connects different group-specific half-bridge circuits X to two or more heating coil groups 1 corresponding to the two or more objects Q to be heated. In other words, the group-specific half-bridge circuits X and the heating coil groups 1 are connected to each other in a one-to-one relationship.

[0039] The relay control unit 32 controls the relays so that the heating coils a to d that are not located below or near the object Q to be heated are not energized and such heating coils are not connected to the group-specific half-bridge circuits X.

[0040] 2-5-3. Inverter control unit 33 The inverter control unit 33 controls the power (supply power) supplied from the inverter circuit to the heating coil group 1. More specifically, the inverter control unit 33 controls the supply power by transmitting control signals for controlling the on / off of switching elements in each of the half-bridge circuits X and Y to the inverter device 2 and controlling the driving of the inverter circuit.

[0041] More specifically, the inverter control unit 33 adjusts the power supplied to the heating coil group 1 that heats the object Q to be heated, in accordance with the heating power set by the user for each object Q to be heated.

[0042] Furthermore, the inverter control unit 33 can individually adjust the power supply to the plurality of objects Q to be heated by individually controlling the driving of each group of half-bridge circuits X (simultaneous heating mode).

[0043] The inverter control unit 33 adjusts the supplied power by a so-called phase shift method. As shown in Figure 4, the phase shift method fixes the switching duty of each half-bridge circuit X and Y (here, the duty is 50%), and then adjusts the switching timing of each half-bridge circuit X and Y to change the potential V of the group-specific half-bridge circuit X. A and the potential V of the common half-bridge circuit Y B By adjusting the phase difference between O It adjusts the effective value of

[0044] Specifically, the group-specific half-bridge circuits X are driven out of phase with respect to the common half-bridge circuit, so that a voltage is output from the inverter circuit to the heating coil.

[0045] The out-of-phase voltage is the voltage V of the group-specific half-bridge circuit X shown in Figure 4(1)(2). A and the potential V of the common half-bridge circuit B This refers to a state in which the two phases are shifted from each other (0°<phase difference≦180°), as in the relationship between the phases of the two signals. Here, the state in which the phase difference is 180° and the two phases are opposite to each other, as shown in Figure 4(1), is called anti-phase.

[0046] In the case of Figure 4(1), the output voltage V O = 0, the zero voltage period is the shortest and the power supply is large. In contrast, in the case of Figure 4(2), the ratio of the zero voltage period is large, so the power supplied from the inverter circuit is small.

[0047] Also, the potential V of the group-specific half-bridge circuit X shown in FIG. 4(3) A and the potential V of the common half-bridge circuit Y. B In the case of Figure 4(3), the output voltage V O Since the effective value of is 0, the supplied power is also 0.

[0048] 2-5-4. Power calculation unit 34 The power calculation unit 34 calculates the actual power supplied from the inverter circuit 21 to each object to be heated Q based on the detected current and voltage detected by the current detection unit 4 and the voltage detection unit 5. The power calculation unit 34 transmits the calculated actual power to the inverter control unit 33.

[0049] As described above, the current detection unit 4 detects the current supplied to the inverter device 2, so the detected current of the current detection unit 4 is the sum of the currents supplied from the inverter device 2 to multiple heated objects Q (heating coil group 1).

[0050] Therefore, the power calculation unit 34 of this embodiment calculates the power to be supplied to each object to be heated Q (heating coil group 1) based on the driving state of each heating coil group 1, the detected current, and the detected voltage.

[0051] For example, the power calculation unit 34 calculates the power to be supplied to one heating coil group 1 based on the detected current in a state in which the driving of all heating coil groups 1 except for one heating coil group 1 is temporarily stopped (a state in which the supplied power is zero).

[0052] 3.Operation The simultaneous heating mode and the power calculation mode executed by the inverter device 2 based on a control signal from the inverter control unit 33 will be specifically described below.

[0053] 3-1. Heating operation (simultaneous heating mode) Here, the simultaneous heating mode will be explained using as an example a state in which multiple objects to be heated Q (here, a pot Q1 and a pan Q2) are placed on a top plate P as shown in FIG.

[0054] As shown in FIG. 5(1), the inverter control unit 33 of this embodiment drives all common half-bridge circuits Y in the same phase, while driving each group-specific half-bridge circuit X out of phase with respect to these common half-bridge circuits, thereby simultaneously heating the pot Q1 and the pan Q2.

[0055] At this time, the phase difference between the two group-specific half-bridge circuits X with respect to the common half-bridge circuit Y is determined based on the heating power settings received from the user for each of the pot Q1 and the pot Q2.

[0056] In Figure 5(1), when pot Q1 is set to high heat and pot Q2 is set to medium heat, the individual half-bridge circuit X1 is driven in reverse phase (180° phase difference) with respect to the common half-bridge circuits Y1 and Y2, and the individual half-bridge circuit X2 is driven with a phase difference of 90° with respect to the common half-bridge circuits Y1 and Y2. Here, the duty of each half-bridge circuit is 50%.

[0057] In this way, by driving each group of half-bridge circuits individually, the output voltage V O The effective values ​​of can be made different from each other, and the power supplied to pot Q1 and pot Q2 can be adjusted separately.

[0058] Here, the output voltage V to the heating coil group 1(a, b) O Since the zero voltage period is minimized, the output voltage is V O The effective value of can be maximized.

[0059] 3-2. Power calculation operation (power calculation mode) In the simultaneous heating mode described above, inverter control unit 33 needs to grasp the actual power supplied to pot Q1 and pot Q2 in order to individually adjust the power supplied to them in accordance with the heating power set by the user.

[0060] However, as described above, in a state where power is supplied to a plurality of heating coil groups 1 at the same time, the power calculation unit 34 of this embodiment cannot calculate the power to be supplied to each heating coil group 1.

[0061] Therefore, the inverter control unit 33 executes a power calculation mode in which the supply of power to pot Q1 (heating coil group a, b) or pot Q2 (heating coil group (c, d)) is temporarily stopped during execution of the simultaneous heating mode as shown in Figure 5 (1).

[0062] To stop power to pot Q2, for example, one could turn off the switching circuit of group-specific half-bridge circuit X2 connected to heating coil group 1(c, d), as shown in Figure 5(2). This would prevent current from flowing through the switching element, and it would be possible to stop the power supply to heating coil group 1(c, d). However, in reality, when the two common half-bridge circuits Y1 and Y2 are operating, a voltage is applied to heating coil group 1(c, d). Even if the switching element of group-specific half-bridge circuit X2 is turned off, a small current may still flow to heating coil group 1(c, d) through a snubber capacitor or diode connected in parallel with the switching element.

[0063] Therefore, in the power calculation mode of this embodiment, in order to more reliably stop the supply of power to the heating coil group 1, one of the two group-specific half-bridge circuits X is controlled to operate in the same phase as the common half-bridge circuit Y.

[0064] For example, as shown in Figure 5(3), when the group-specific half-bridge circuit X2 is driven in phase, the output voltage V Obecomes 0, and the current supplied to pot Q2 becomes 0. In this case, as shown in Figure 6, the current detected by current detection unit 4 becomes equal to the current supplied to pot Q1. Power calculation unit 34 calculates the actual power supplied to pot Q1 from this detected current and detected voltage. Furthermore, power calculation unit 34 determines the current supplied to pot Q2 from the difference between the current detected in simultaneous heating mode (the sum of the currents supplied to pots Q1 and Q2) and the current supplied to pot Q1, and uses this to calculate the actual power supplied to pot Q2.

[0065] The calculated power supply to pot Q1 and pot Q2 is fed back to inverter control unit 33 and used to adjust the heating power.

[0066] Alternatively, the group-specific half-bridge circuit X1 may be driven in phase with the common half-bridge circuit Y to calculate the power supplied to the pot Q1 and the pan Q2.

[0067] This power calculation mode is executed at a predetermined timing in the simultaneous heating mode (for example, at regular intervals), and its duration is preferably longer than the time required for the current detected by the current detection unit 4 to settle to a steady value, and long enough that it does not affect the heating of the heated object Q.

[0068] 4.Effects In the induction heating device 100 configured in this manner, the inverter circuit 21 is connected in parallel only to the heating coil corresponding to the object to be heated Q placed on the top plate P, which reduces the number of parts and makes the device more compact than when an inverter circuit 21 is provided for each heating coil.

[0069] The use of a full-bridge inverter circuit 21 with high power conversion efficiency reduces power loss. Furthermore, since it can handle large amounts of power, the inverter circuit 21 can be connected in parallel to multiple heating coils. Furthermore, the full-bridge design makes it possible to adjust the heating power using the so-called phase shift method.

[0070] In the phase-shifted system, the potential V of the common half-bridge circuit Y B and the potential V of the group-specific half-bridge circuit X A Since the heating power is adjusted based on the phase difference between the heating coil groups 1 and 2, the driving conditions (frequency, duty, phase) of the common half-bridge circuit Y can be fixed in the multiple inverter circuits 21 that heat each object Q under different heating conditions. This means that each common half-bridge circuit Y can be connected to any heating coil group 1, eliminating the need to provide a relay circuit 22 between the heating coil group 1 and the common half-bridge circuit Y. This makes it possible to reduce the number of parts.

[0071] Since a power calculation mode is executed in which the group-specific half-bridge circuits X are driven in phase with the common half-bridge circuit Y, the power calculation unit 34 can accurately calculate the power supplied to each object to be heated Q even when the common half-bridge circuit Y being driven is connected to each heating coil group 1. Furthermore, by executing this power calculation mode, the power supplied to each object to be heated Q can be calculated using a single ammeter that measures the current supplied to the inverter device 2, eliminating the need to provide a current sensor for each object to be heated Q or each heating coil, which leads to a reduction in the number of parts.

[0072] Because a common power supply is connected to each half-bridge circuit X, Y, the range of potentials that each half-bridge circuit X, Y can assume can be made uniform, and the potential difference can be made zero between the group-specific half-bridge circuit X and the common half-bridge circuit Y. This makes it possible to easily and as small as possible the power supplied to some of the heating coil groups 1 in the power calculation mode, and makes it possible to more accurately measure the power supplied to each object to be heated Q.

[0073] Since the same number of group-specific half-bridge circuits X and common half-bridge circuits Y are provided, the loss due to switching can be reduced compared to when the numbers of the two types of half-bridge circuits are not the same.

[0074] [Second embodiment] The inverter device of the above embodiment has two group-specific half-bridge circuits and heats two objects to be heated simultaneously in the simultaneous heating mode.

[0075] In contrast to this, the inverter device according to the second embodiment includes three or more group-specific half-bridge circuits, and heats three or more objects to be heated simultaneously in the simultaneous heating mode.

[0076] In the power measurement mode of this embodiment, some of the three or more group-specific half-bridge circuits are driven in phase with the common half-bridge circuit connected to the group-specific half-bridge circuit via the heating coil group.

[0077] The power measurement mode of the second embodiment will be specifically described using an example in which the inverter device has three group-specific half-bridge circuits X1 to X3. For example, Figure 7(1) shows the change in the detected current when one group-specific half-bridge circuit X3 is driven in phase with the common half-bridge circuit in the power measurement mode. In this case, the power calculation unit calculates the power supplied from one group-specific half-bridge circuit X3 to one object to be heated based on the difference between the detected current in the simultaneous heating mode and the detected current in the power calculation mode.

[0078] 7(2) shows the change in the detected current when the two group-specific half-bridge circuits X2 and X3 are driven in phase with the common half-bridge circuit in the power measurement mode. In this case, the power calculation unit calculates the power supplied to one heated object from the remaining group-specific half-bridge circuit X1 based on the difference between the detected current in the simultaneous heating mode and the detected current in the power calculation mode.

[0079] Furthermore, the inverter control unit of the second embodiment executes the power calculation mode while switching among some of the group-specific half-bridge circuits that are driven in phase with the common half-bridge circuit. For example, as shown in FIG. 7(1), when one group-specific half-bridge circuit is driven in phase with the common half-bridge circuit, the inverter control unit executes the power calculation mode while switching the group-specific half-bridge circuit from X1 to X2 to X3. The power calculation unit then calculates the current supplied to each object based on the driving status and detected current of each group-specific half-bridge circuit, and calculates the power supplied to each object based on this.

[0080] [Other embodiments] In each of the above embodiments, the same voltage is supplied to each half-bridge circuit from a common power supply, but they may be connected to different power supplies or may be supplied with different voltages.

[0081] The inverter device in each of the above embodiments has the same number of common half-bridge circuits as the group-specific half-bridge circuits, but the number of common half-bridge circuits is not limited to this.

[0082] In each of the above-described embodiments, a relay circuit is not provided between the common half-bridge circuit and the heating coil, but it may be provided.

[0083] In the above embodiments, the common half-bridge circuits are all driven in the same phase, but this is not limiting. At least the common half-bridge circuits that are not connected to the group-specific half-bridge circuits via the heating coils may not be driven, and the common half-bridge circuits that are not connected to the same heating coil group may be driven in different phases.

[0084] In each of the above-described embodiments, a relay circuit is provided for each heating coil, but it is not necessary that a relay circuit is provided for some or all of the heating coils.

[0085] The inverter control unit in each of the above embodiments adjusts the supply power using a phase shift method, but it may also adjust the supply power using a frequency control method or a duty control method, or a combination of these with the phase shift method.

[0086] In the power calculation mode of each of the above-described embodiments, driving the group-specific half-bridge circuit and the common half-bridge circuit in phase means driving them in a state where there is no phase shift in their potentials (phase difference = 0°), but in the power calculation mode, the phase difference between the two half-bridge circuits does not necessarily have to be 0. The effects of the present invention can be achieved if the phases of the two circuits are close enough (if they are approximately in phase) that almost no current flows between these group-specific half-bridge circuits and the common half-bridge circuit.

[0087] The present invention may also be applied to a contactless power supply device that includes a power supply coil instead of a heating coil.

[0088] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0089] 100...Induction heating device 1. Heating coil group a~d Heating coil 2. Inverter device X...Grouped half-bridge circuit Y Common half-bridge circuit 21 Inverter circuit 22 Relay circuit 3. Control equipment 31 ...Location specifying section 32 Relay control section 33 Inverter control unit 34 Power calculation section 4 Current detection section 5. Voltage detection section P···Top plate Q ···The object being heated

Claims

1. a plurality of heating coil groups each including one or more heating coils for induction heating different objects to be heated; an inverter device that supplies power to the heating coil group; a current detection unit that detects a current supplied to the inverter device; a control device for controlling the inverter device, the inverter device includes a plurality of group-specific half-bridge circuits each connected to one of the heating coil groups, and a common half-bridge circuit each connected to the plurality of heating coil groups and constituting a full-bridge inverter circuit together with the group-specific half-bridge circuits, The control device an inverter control unit that causes the inverter device to execute a power calculation mode in which some of the plurality of group-specific half-bridge circuits and the common half-bridge circuit connected to the some of the group-specific half-bridge circuits are driven in phase; and a power calculation unit that calculates the power to be supplied from the inverter device to at least one of the heating coil groups based on the current value detected by the current detection unit in the power calculation mode.

2. 2. The induction heating device according to claim 1, wherein in the power calculation mode, the induction heating device is controlled so that a potential difference between the other group-specific half-bridge circuits and the common half-bridge circuit becomes zero.

3. the inverter control unit causes the inverter device to execute a simultaneous heating mode in which the plurality of group-specific half-bridge circuits are driven out of phase with the common half-bridge circuit connected to the plurality of group-specific half-bridge circuits, The induction heating device according to claim 1 , wherein the power calculation mode is executed at a predetermined timing in the simultaneous heating mode.

4. The induction heating device according to claim 1 , wherein the inverter control unit executes the power calculation mode while switching between the partial group half-bridge circuits that are driven in phase with the common half-bridge circuit.

5. 2. The induction heating device according to claim 1, wherein the inverter device has the same number of group-specific half-bridge circuits and the same number of common half-bridge circuits.

6. The induction heating device according to claim 1 , further comprising a relay circuit provided between the heating coil and the group-specific half-bridge circuit, for switching the group-specific half-bridge circuit connected to each of the heating coils.

7. The heating device includes a plurality of heating coil groups each consisting of one or more heating coils for induction heating different objects to be heated, an inverter device for supplying power to the heating coil groups, a current detection unit for detecting a current supplied to the inverter device, and a control device for controlling the inverter device, a program used in an induction heating device, the inverter device having a plurality of group-specific half-bridge circuits each connected to one of the heating coil groups, and a common half-bridge circuit each connected to a plurality of the heating coil groups and constituting a full-bridge inverter circuit together with the group-specific half-bridge circuits, an inverter control unit that causes the inverter device to execute a power calculation mode in which some of the plurality of group-specific half-bridge circuits and the common half-bridge circuit connected to the some of the group-specific half-bridge circuits are driven in phase; A program for an induction heating device that causes the control device to function as a power calculation unit that calculates the power supplied from the inverter device to at least one of the heating coil groups based on the current value detected by the current detection unit in the power calculation mode.

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