JP2015128078A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an induction heating cooker which has a plurality of heating coils per one heating port and improve a heating distribution when a predetermined heating mode is selected.SOLUTION: An induction heating cooker comprises: load resistance detection means 20 for detecting a load by using detection results by output power detection means 14a-14e and output current detection means 12a-12e; control means 19 for controlling drive of a plurality of inverter circuits 6a-6e on the basis of detection results by the output power detection means 14a-14e, the output current detection means 12a-12e and the load resistance detection means 20; and operation means 105 for inputting instructions of start/stop of heating, preset heating power and a hating mode to the control means 19. The load resistance detection means 20 detects a load by causing each load circuit to be electrically conducted independently. The control means 19 includes a heating mode for presetting a power distribution to each of the heating coils 16a-16e or each of the inverter circuits 6a-6e on the basis of the load detection result.

Description

  The present invention relates to an induction heating cooker including a plurality of heating coils for one heating port.

  In a conventional induction heating cooker, for example, a top plate on which an object to be heated is placed, a plurality of heating coils arranged close to the top plate, and a circuit that supplies high-frequency power to each heating coil And load detecting means for detecting that an object to be heated is placed for each heating coil (see, for example, Patent Document 1).

JP 2008-293871 A (Claim 2)

The technique of the above-mentioned patent document 1 determines the presence or absence of a load for each heating coil, and the circuit supplies a high-frequency current only to the heating coil in which the load detecting means detects that an object to be heated is placed on the upper side. Therefore, the heating efficiency when heating a small pot is improved, and the temperature unevenness when heating a large pot is suppressed.
However, in the state where a plurality of heating coils are arranged close to each other and a high-frequency current is flowing at the same time, whether or not there is a load to be heated above the heating coils due to the influence of magnetic coupling between adjacent heating coils. This makes it difficult to discriminate and to determine the size of the load to be heated, and there is a problem that the cooking object cannot be heated with the heating distribution desired by the user.

  The present invention has been made to solve the above-described problem, and in an induction heating cooker having a plurality of heating coils for one heating port, a heating distribution when a predetermined heating mode is selected. Get an improved one.

  An induction heating cooker according to the present invention includes a top plate on which a cooking container, which is an object to be heated, is placed, and a plurality of top plates arranged below the top plate and arranged close to one heating port. A heating coil, a plurality of inverter circuits for supplying high-frequency power to a plurality of load circuits each having the heating coil, and a power output from the plurality of inverter circuits to the plurality of load circuits, respectively, or a plurality of inverter circuits. A power detection unit that detects input power, an output current detection unit that detects output currents of the plurality of inverter circuits, and a load that performs load detection using detection results of the power detection unit and the output current detection unit Based on detection results of the detection means, the power detection means, the output current detection means, and the load detection means, the plurality of inverter circuits Control means for dynamic control, and operation means for inputting heating start / stop and set heating power and heating mode instructions to the control means, and the load detection means is configured to load each load circuit as a single energized state. The control means includes a heating mode for setting power distribution for each heating coil or each inverter circuit based on the load detection result.

  In the present invention, when a predetermined heating mode is selected by the operation means, the control means controls the load detection means to perform load detection in which a single energization state is set for each heating coil or each inverter circuit, and the load Since power distribution for each heating coil or each inverter circuit is set based on the detection result, load detection is not performed in a state where a high-frequency current flows simultaneously to a plurality of heating coils arranged close to each other, and between the heating coils. The load to be heated can be detected while suppressing the influence of magnetic coupling, and power distribution to each heating coil is performed based on the result. The object to be heated can be heated.

It is a figure which shows the structure of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure which shows the circuit structure of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a figure which shows the example of arrangement | positioning of the some heating coil with respect to one heating port of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a flowchart which shows the heating control process which the control means of the induction heating cooking appliance which concerns on Embodiment 1 performs. It is a flowchart which shows the load detection process which the load detection means in the control means of the induction heating cooking appliance which concerns on Embodiment 1 performs. It is a flowchart which shows the target electric power distribution process which the control means of the induction heating cooking appliance which concerns on Embodiment 1 performs. It is a figure which shows the example of the drive signal to the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 1. FIG. It is a flowchart which shows the load detection process which the load detection means in the control means of the induction heating cooking appliance which concerns on Embodiment 2 performs. It is a figure which shows the example of the drive signal to the inverter circuit of the induction heating cooking appliance which concerns on Embodiment 2. FIG. It is a flowchart which shows the heating control process in the control means of the induction heating cooking appliance which concerns on Embodiment 3. It is a figure which shows another circuit structure of the induction heating cooking appliance which concerns on embodiment. It is a figure which shows another circuit structure of the induction heating cooking appliance which concerns on embodiment. It is a figure which shows another example of arrangement | positioning of the several heating coil of the induction heating cooking appliance which concerns on embodiment.

Embodiment 1 FIG.
1 is a diagram illustrating a configuration of an induction heating cooker according to Embodiment 1. FIG.
In FIG. 1, 101 is a top plate, 102 is a main body housing, 103 is a circuit for supplying a high-frequency current, 104 is an operation unit, 105 is a display means, and 16 is a heating coil.
The top plate 101 is for placing an object to be heated such as a pan, and is provided with a heating port 106 for displaying the placement position of the pan. A circuit 103, a display unit 105, and a heating coil 16 are housed inside the main body housing 102, and a top plate 101 is placed on the upper surface to house the internal structure of the main body housing 102.
The circuit 103 has a configuration described later with reference to FIG. 2 and supplies a high-frequency current to the heating coil 16.
The operation unit 104 is for the user to adjust the heating output, and can select a plurality of heating modes. For example, it is possible to select a uniform heating mode for baking a hot cake or the like, or a heating mode such as boiling water that gives priority to heating efficiency over heating distribution. Here, high heating efficiency means that the load resistance value of the heating coil is large, and a larger heating output can be obtained with a small coil current.
The display means 105 is a screen display device composed of a liquid crystal display device or the like, and displays the operating state of the induction heating cooker.
A plurality of heating coils 16 are arranged adjacent to each heating port 106. In the present embodiment, five heating coils 16 are arranged for each heating port 106.

FIG. 2 is a diagram showing a circuit configuration of one heating mouth of the induction heating cooker according to the first embodiment.
The induction heating cooker is connected to an AC power source 1, and power supplied from the AC power source 1 is converted into DC power by a DC power supply circuit 2.
The DC power supply circuit 2 includes a rectifier diode bridge 3 that rectifies AC power, a reactor 4a to 4e and a smoothing capacitor 5a to 5e provided for each of the inverter circuits 6a to 6e. DC power is supplied to a plurality of inverter circuits 6a to 6e provided according to the number of load circuits 15a to 15e each having .about.16e.

  Each of the inverter circuits 6a to 6e has the same configuration, and two switching elements (upper switches) 7a to 7e, switching elements (lower switches) 8a to 8e connected in series between the DC buses of the DC power supply circuit 2, respectively. The diodes 9a to 9e, 10a to 10e connected in reverse parallel to the switching element, and the two series switching elements are alternately turned on / off at high frequencies by the drive circuits 11a to 11e, and the output terminals thereof A high-frequency voltage is generated between one end of the DC bus and one end of the DC bus. The high-frequency voltages output from the inverter circuits 6a to 6e are detected by the output voltage detection means 13a to 13e. The output current of the inverter circuit also flows through the heating coil, and is detected by the output current detection means 12a to 12e. . Further, 14a to 14e integrate the output voltage value detected by the output voltage detection means 13a to 13e and the output current detection means 12a to 12e and the output current value (heating coil current value) to obtain the output power value of the inverter circuit. This is output power detection means to be generated.

  Load circuits 15a to 15e are connected between the output terminals of the inverter circuits 6a to 6e and the low potential bus of the DC power source. The load circuits 15a to 15e are composed of a series circuit of heating coils 16a to 16e and resonance capacitors 17a to 17e, and clamp diodes 18a to 18e connected in parallel to the resonance capacitors 17a to 17e. The clamp diodes 18a to 18e clamp the connection point potential between the heating coils 16a to 16e and the resonance capacitors 17a to 17e to the low potential side bus potential of the DC power supply. By the action of the clamp diodes 18a to 18e, the current flowing through the heating coils 16a to 16e is not commutated when the lower switches 8a to 8e are in a conductive state.

The control means 19 performs drive control of each inverter circuit 6a-6e, and controls the drive circuits 11a-11e based on the output current and output power of each inverter circuit 6a-6e. Also, the load resistance detection means 20 provided in the control means 19 is based on the power detected by the output power detection means 14a-14e and the current detected by the output current detection means 12a-12e. The load resistance value R of 15e is detected and constitutes a load detection means. The load resistance value R is obtained by the following formula.
R = (output power value) / (output current value) ²
This load resistance value R increases or decreases due to a loss (heat generation) due to an induced eddy current generated by linking the magnetic flux generated by the high-frequency current flowing through each heating coil 16a to 16e to the pan bottom placed above the heating coil. The load resistance value R increases as the pan bottom facing the heating coil is wider. Therefore, the presence / absence and size of the pan (load) placed above the heating coil can be determined from the value of the load resistance value R. Therefore, the threshold value R1 is set so that it is possible to distinguish between a state where an appropriate pan is placed above the heating coil and a state where it is not placed. The threshold value R1 varies depending on the number of turns of the copper wire of the heating coil, but is set to, for example, about several Ω (2Ω to 5Ω).

  FIG. 3 shows an arrangement example of the heating coils of the induction heating cooker according to the first embodiment. 3A is a side view showing the arrangement of the heating coils, and FIG. 3B is a plan view showing the arrangement of the heating coils. As shown in the figure, five heating coils 16a to 16e are arranged close to one heating port of the induction heating cooker according to the present embodiment, and are placed above the heating coils 16a to 16e via the top plate 101. A cooking vessel pan 22 as an object to be heated is placed.

  FIG. 4 is a flowchart showing a heating control process by the control means 19 of the induction heating cooker according to the present embodiment, and FIG. 5 is executed by a load detection means for determining the presence and size of a pan (load) above each heating coil. FIG. 6 is a flowchart showing target power distribution processing for assigning heating power output from each heating coil. Hereafter, the operation | movement in the control means of the induction heating cooking appliance which concerns on this Embodiment 1 is demonstrated using these flowcharts.

  In FIG. 4, first, the control means 19 determines whether or not a heating request instruction input such as a heating power setting is input from the operation unit 104 (step 1). In order to determine whether the pan to be heated is placed or not, a load detection process is executed (step 2).

As shown in FIG. 5, in the load detection process, first, the drive circuit 11a is controlled to drive the inverter circuit 6a for the heating coil 16a, and a predetermined high-frequency voltage is applied to the load circuit 15a including the heating coil 16a ( Step 2-1-1). At this time, control is performed so that a high frequency voltage is not applied to the load circuits 15b to 15e including the other heating coils 16b to 16e, respectively. Then, the output current detection means 12a and the output power detection means 14a detect the high frequency current of the heating coil 16a and the high frequency power output from the inverter circuit 6a (step 2-1-2), and the detected power W and output The load resistance detection means 20 calculates the load resistance value R (= W / I ² ) from the current value I (step 2-1-3). And it is discriminate | determined by the load resistance value R whether the suitable pan is mounted above the heating coil 16a (step 2-1-4). When the load resistance value R is less than the threshold value R1, it is determined that there is no proper load, and the resistance value data for target power distribution is set to Ra = 0 (step 2-1-5). When the load resistance value R is equal to or greater than R1, the load state is determined to be loaded, and the load resistance value data for target power distribution is set to Ra = R (step 2-1-6). Above, the inverter circuit load detection process (step 2-1) which concerns on the heating coil 16a is complete | finished.

  Hereinafter, in the same manner, for the heating coils 16b to 16e, it is determined whether or not an appropriate pan is placed above the heating coil and related to the size of the placed pan (load) 22. In order to acquire load resistance value data for target power distribution to be performed, inverter circuit load detection processing is performed (steps 2-2 to 2-5). Also at this time, for each heating coil, control is performed so that the high-frequency voltage is applied only to the load circuit including the heating coil and no high-frequency voltage is applied to the load circuit including the other heating coils.

  Returning to FIG. 4, after the load detection process (step 2) is completed, it is determined whether or not there is a heating coil on which an appropriate load is placed (step 3), and there is no appropriate load above any of the heating coils. If so, return to Step 1. If there is an appropriate load above any of the heating coils, a target power distribution process for each of the heating coils 16a to 16e is performed (step 4).

  As shown in FIG. 6, the target power distribution process distributes the entire heating power Wall set by the operation unit 104 to the target power for each of the heating coils 16 a to 16 e based on the load resistance value data of each heating coil.

First, for the heating coil 16a (step 4-1), it is determined whether there is an appropriate load (step 4-1-1). If there is no appropriate load, the target power is set to 0 (step 4-1-2). ). When there is an appropriate load, the target power Wa of the heating coil 16a is determined from the overall heating power Wall and load resistance values Ra to Re detected by the load detection means,
Wa = Wall × Ra / (Ra + Rb + Rc + Rd + Re)
Is set (step 4-1-3).

Similarly, target power setting processing is performed for each of the heating coils 16b to 16e (steps 4-2 to 4-5). In addition, the target power of each heating coil is
Wb = Wall × Rb / (Ra + Rb + Rc + Rd + Re) (Step 4-2-3) Wc = Wall × Rc / (Ra + Rb + Rc + Rd + Re) (Step 4-3-3) Wd = Wall × Rd / (Ra + Rb + Rc + Rd + Re) · (Step 4-4-3) We = Wall × Re / (Ra + Rb + Rc + Rd + Re) (Step 4-5-3) As shown in (Step 4-5-3), a value proportional to the load resistance value R of each heating coil is set. . If it sets in this way, if each heating coil 16b-16e is the same coil, the heating density [(output of a heating coil) / (area of the part facing a pan of a heating coil)] of each coil may be made the same. it can.

  Returning to FIG. 4, when the setting of the target power of each heating coil (step 4) is completed, the drive circuit is controlled for the inverter circuit of the heating coil that is determined to have an appropriate load placed thereon, and the inverter output is output. Start (step 5), output current detection means 12a-12e and output power detection means 14a-14e detects the output current and power of each inverter circuit 6a-6e (step 6). And the output control process of the inverter circuits 6a-6e is performed for every heating coil 16a-16e.

In the output control process (step 7) of the heating coil 16a, first, it is determined whether the inverter circuit 6a is being driven (step 7-1). If it is not being driven, the process is terminated. It is determined whether or not the output current of the flowing inverter circuit 6a is excessive (step 7-2). If it is not excessive, the target power Wa of the heating coil 16a and the detected power W are compared (step 7-3). As a result, if the detected power of the heating coil 16a is smaller than the target power, control is performed to increase the inverter circuit output (step 7-4). If the detected power is substantially equal to the target power, the inverter circuit output is increased. Keep it as it is. If it is determined in step 7-2 that the current of the heating coil 16a is excessive, or if it is determined in step 7-3 that the detected power W is larger than the target power Wa, control for reducing the inverter circuit output is performed. (Step 7-5).
For the other heating coils 16b to 16e, the inverter circuits 6b to 6e are controlled similarly to the heating coil 16a (steps 8 to 11).

Next, it is determined whether or not there is a heating stop request from the operation unit 104 (step 12), and when there is a stop request, the drive circuits 11a to 11e are controlled to stop driving all the inverter circuits 6a to 6e (step). 13) Return to Step 1.
If there is no heating stop request in step 12, it is determined whether or not there is a set heating power change request (step 14). If there is no heating power change request, the process directly returns to step 6. On the other hand, when there is a heating power change request, the heating mode selected by the operation unit 104 is determined (step 15), and the selected heating mode is a heating mode that gives priority to the heating distribution control (for example, the uniform heating mode ( In the case of a mode in which the entire pan bottom of a large-diameter pan is heated uniformly, a heating mode in which the heating density of the external heating coil is increased in order to increase the heating of the pan outer periphery, a heating mode emphasizing the pan outer periphery, etc.) To control all the inverter circuits 6a to 6e (step 16), return to the load detection means of step 2 to perform load detection processing for each heating coil, and to-be-heated objects (pans) above each heating coil The load resistance values Ra to Re related to the magnitude of the are detected. An example of the drive signal of the inverter circuit at that time is shown in FIG.

  If the heating mode selected in step 15 is a heating mode that prioritizes heating efficiency and operability over the heating distribution, the process returns to step 4 and is based on the load resistance value of each heating coil detected at the start of heating. Distribute firepower.

  As described above, in the present embodiment, a plurality of heating coils are arranged adjacent to one heating port, and a high-frequency current is allowed to flow only through the heating coil on which an object to be heated (pan) is placed. In the induction heating cooker, because it includes a predetermined heating mode such as a uniform heating mode in which simultaneous energization to a plurality of heating coils is stopped every time the set heating power is changed, and load detection means for each heating coil is included, in this heating mode, At any time, the presence or size of the object to be heated for each heating coil that excludes the influence of magnetic coupling between the heating coils is detected, and power is distributed and controlled so as to obtain a desired heating distribution. In other heating modes, Induction heating that reduces the operability and heating efficiency as much as possible while ensuring the finish of cooking according to the heating mode, since the heating output and heating efficiency are not reduced due to load detection means when changing the heating power, etc. It is possible to obtain a physical device.

Embodiment 2. FIG.
FIG. 8 is a flowchart showing a load detection process executed by the load detection means in the control means of the induction heating cooker according to the second embodiment, and FIG. 9 is a drive signal for the induction heating cooker according to the second embodiment. It is an example. The load detection process executed by the load detection means of the control means of the induction heating cooker according to Embodiment 1 is a load having a heating coil in order to avoid the influence of magnetic coupling between adjacent heating coils. Although a high-frequency current is sequentially applied to each circuit to detect an object to be heated (pan) placed above the heating coil, the second embodiment is a heating that is not adjacent during the load detection process. For the set of load circuits having coils, the load detection time is shortened by simultaneously applying a high-frequency current. In addition, the induction heating cooking appliance which concerns on this Embodiment 2 is a flowchart of FIG. 2 for a circuit structure, FIG. 3 for arrangement | positioning of a heating coil, and the heating control processing of the control means 19 similarly to Embodiment 1. FIG. Shall.

  In the load detection process in the second embodiment, the drive circuit 11a is controlled to drive the inverter circuit 6a to perform the load detection process (step 2-1) of the heating coil 16a in FIG. (Step 2-1-1), and the high-frequency current and high-frequency power flowing through the heating coil 16a are detected by the output current detection means 12a and the output power detection means 14a (step 2-1-2). Then, the load resistance value R (a) is calculated from the output current and power detected for the heating coil 16a (step 2-1-3), and it is determined whether or not there is a heated load (pan) above the heating coil 16a. The load resistance value is compared with a threshold value R1 (step 2-1-4). As a result, when the load resistance value R (a) is smaller than the threshold value R1, it is determined that there is no heating load above the heating coil 16a, and the heating power distribution resistance value: Ra = 0 (step 0). 2-1-5). On the other hand, when the load resistance value R (a) is equal to or greater than the threshold value R1, it is determined that there is an object to be heated above the heating coil 16a, and the resistance value for heating power distribution: Ra = R (a) (Step 2-1-6).

  Next, in order to perform load detection processing (step 2-6) of the heating coils 16b and 16c that are not adjacent to each other, the drive circuits 11b and 11c are controlled to drive the inverter circuits 6b and 6c, and a predetermined high-frequency output is performed. (Step 2-6-1), and the high-frequency current and high-frequency power flowing through the heating coils 16b and 16c are detected by the output current detection means 12b and 12c and the output power detection means 14b and 14c (step 2-6-2). . Then, load resistance values R (b) and R (c) are calculated from the output current and power detected for the heating coils 16b and 16c (step 2-6-3), and the heated load (pot) above the heating coil 16b is calculated. ) Is compared with the threshold value R1 of the load resistance value (step 2-6-4). As a result, when the load resistance value R (b) is smaller than the threshold value R1, it is determined that there is no heating load above the heating coil 16b, and the heating power distribution resistance value: Rb = 0 (step) 2-6-5). On the other hand, when the load resistance value R (b) is greater than or equal to the threshold value R1, it is determined that there is an object to be heated above the heating coil 16b, and the resistance value for heating power distribution: Rb = R (b) (Step 2-6-6).

  Next, in order to determine the presence or absence of a heated load (pan) above the heating coil 16c, the load resistance value is compared with a threshold value R1 (step 2-6-7). As a result, if the load resistance value R (c) is smaller than the threshold value R1, it is determined that there is no heating load above the heating coil 16c, and the resistance value for heating power distribution: Rc = 0 (step) 2-6-8). On the other hand, if the load resistance value R (c) is equal to or greater than the threshold value R1, it is determined that there is an object to be heated above the heating coil 16c, and the resistance value for heating power distribution: Rc = R (c) (Step 2-6-9).

  Next, similarly to the load detection process (step 2-6) for the heating coils 16b and 16c that are not adjacent to each other, the load detection process (step 2-7) for the heating coil 16d and the heating coil 16e that are not adjacent to each other is to be performed. The drive circuits 11d and 11e are controlled to drive the inverter circuits 6d and 6e, and a predetermined high-frequency output is performed (step 2-7-1, not shown, corresponding to step 2-6-1), and the output current. The detection means 12d and 12e and the output power detection means 14d and 14e detect the high-frequency current and high-frequency power flowing in the heating coil 16d and the heating coil 16e (step 2-7-2, not shown, step 2-6-2). Correspondence.). Then, load resistance values R (d) and R (e) are calculated from the output current and power detected for the heating coils 16d and 16e (step 2-7-3, not shown, corresponding to step 2-6-3). In order to determine the presence or absence of a heated load (pan) above the heating coil 16d, it is compared with a load resistance threshold value R1 (step 2-7-4, not shown, step 2-6-4) Correspondence.). As a result, when the load resistance value R (d) is smaller than the threshold value R1, it is determined that there is no heating load above the heating coil 16d, and the heating power distribution resistance value: Rd = 0 (step) 2-7-5, not shown, corresponding to step 2-6-5). On the other hand, when the load resistance value R (d) is equal to or greater than the threshold value R1, it is determined that there is an object to be heated above the heating coil 16d, and the resistance value for heating power distribution: Rd = R (d) (Step 2-7-6, not shown, corresponding to Step 2-6-7).

  Next, in order to determine the presence or absence of a heated load (pan) above the heating coil 16e, the load resistance value is compared with a threshold value R1 (step 2-7-7, not shown, corresponding to step 2-6-7). .) As a result, when the load resistance value R (e) is smaller than the threshold value R1, it is determined that there is no heating load above the heating coil 16e, and the heating power distribution resistance value: Re = 0 (step 0) 2-7-8, not shown, corresponding to step 2-6-8). On the other hand, if the load resistance value R (e) is equal to or greater than the threshold value R1, it is determined that there is an object to be heated above the heating coil 16e, and the resistance value for heating power distribution: Re = R (e) (Step 2-7-9, not shown).

  FIG. 9 shows examples of drive signals for the inverter circuits 6a to 6e in the load detection process (steps 2-1, 2-6, and 2-7). Since the inverter circuits 6b and 6c are simultaneously driven and then the inverter circuits 6d and 6e are simultaneously driven to perform load detection processing, the load detection processing is performed by sequentially energizing each inverter circuit alone. Compared to the case, the load detection processing time can be shortened.

  As described above, in the second embodiment, a plurality of heating coils are disposed adjacent to one heating port, and a high-frequency current is applied only to the heating coil on which an object to be heated (pan) is placed. In a flowing induction heating cooker, the simultaneous energization of multiple heating coils is stopped every time the set heating power is changed, and the load detection is performed by energizing each load circuit having adjacent heating coils having a large magnetic coupling, and magnetic coupling. It includes a heating mode such as a uniform heating mode in which load detection is performed for each load circuit having a heating coil that is not adjacent to each other. In this heating mode, the heating coil is heated for each heating coil without the influence of magnetic coupling between the heating coils. An induction heating cooker in which the load detection processing period is shortened while detecting the presence / absence / size of an object can be obtained.

Embodiment 3 FIG.
FIG. 10 is a flowchart showing a heating control process in the control means of the induction heating cooker according to the third embodiment. The same steps as those in FIG. 4 are denoted by the same step numbers, and description thereof is omitted. In addition, the induction heating cooking appliance which concerns on this Embodiment 3 assumes that a circuit structure is FIG. 2 similarly to Embodiment 1, and arrangement | positioning of a heating coil is FIG.

  In step 14 of FIG. 10, it is determined whether or not there is a set heating power change request, and when there is no heating power change request, the heating mode selected by the operation unit 104 is determined (step 17), and heating with priority given to heating distribution control is determined. If a mode (for example, uniform heating mode) has been selected, it is determined whether or not a predetermined time has elapsed since the previous load detection process was performed (step 18). If a predetermined time has elapsed, the process proceeds to step 16 After stopping the driving of all the inverter circuits 6a to 6e, the process returns to the load detection means in step 2 to perform the load detection process for each heating coil. If the heating mode selected in step 17 is a heating mode that prioritizes heating efficiency and operability over the heating distribution, or if it is before the predetermined time has elapsed in step 18, the process returns to step 6 and each heating is performed. Controls the output to the coil.

  As described above, in the third embodiment, a plurality of heating coils are arranged adjacent to one heating port, and a high-frequency current is applied only to the heating coil on which an object to be heated (pan) is placed. In the induction heating cooker that flows, including a predetermined heating mode such as a uniform heating mode, in which simultaneous energization to a plurality of heating coils is stopped every time the set heating power is changed, and load detection means for each heating coil is included. Furthermore, by stopping the simultaneous energization of the plurality of heating coils at predetermined time intervals and performing load detection means for each heating coil, the user can use the pan even if there is no instruction to change the set heating power during heating in the predetermined heating mode. Even when the position of the pan or pan is shifted, the presence or size of the object to be heated for each heating coil that eliminates the influence of magnetic coupling between one heating coil is detected, and the power is distributed so that the desired heating distribution is obtained. Distribute and control, In other heating modes, the heating output and heating efficiency are not reduced due to load detection means when changing the heating power, etc., so the cooking finish according to the heating mode does not depend on the change in the placement state of the object to be heated. It is possible to obtain an induction heating cooker that realizes surely and suppresses a decrease in operability and heating efficiency as much as possible.

  The DC power supply circuit 2 of the induction heating cooker according to the above embodiment has one rectifier diode bridge and includes output power detection means for detecting the output power of each inverter circuit. For example, as shown in FIG. 11, each inverter circuit is provided with DC power supply circuits 2a to 2e each having a rectifier diode bridge, and the input current detection means 23a to 23e and the input voltage detection means 24a to 24e provide the input power of the inverter circuit. An induction heating cooker having a circuit configuration for detecting a value may be used.

  In addition, although the circuit structure (FIG. 2) of the induction heating cooking appliance which concerns on the said embodiment has the output electric power detection means 14 of the inverter circuit 6, as shown in FIG. The DC power supply circuit 2 may be provided independently, and a circuit configuration having an input current detection means 23 and an input voltage detection means 24 for detecting an input current and an input voltage to the DC power supply circuit may be used. Since the input current value and the input voltage value detected by the input current detection means 23 and the input voltage detection means 24 are integrated, a value corresponding to the input power input to the inverter circuit 6 can be calculated. 23 and the input voltage detection means 24 constitute input power detection means.

  In addition, the circuit configuration shown in FIG. 2 and FIG. 11 of the induction heating cooker according to the above-described embodiment is such that one inverter circuit corresponds to the load circuit having one heating coil. As shown in FIG. 12, a circuit configuration example having a plurality of heating coils in one load circuit may be used. These heating coils are preferably a set of heating coils that are not adjacent to each other. Even in such a circuit configuration, if the resistance value of the load circuit of each inverter circuit is determined in the predetermined heating mode, each inverter circuit is individually driven to determine the presence or absence of an object to be heated. Presence and size of the object to be heated can be accurately determined for each inverter circuit.

  Moreover, in the said embodiment, although the number of the heating coils with respect to one heating port was shown, the number of this heating coil is not restricted to five, For example, as shown in FIG. Etc.

  Note that the above-described three embodiments may be implemented not only independently but also in combination. For example, the third embodiment may be implemented in combination with the second embodiment, and the same effect is obtained.

  1 AC power supply, 2, 2a-2e DC power supply circuit, 3, 3a-3e rectifier diode bridge, 4a-4e reactor, 5a-5e smoothing capacitor, 6a-6e inverter circuit, 7a-7e upper switch, 8a-8e lower switch , 9a to 9e, 10a to 10e Diode, 11a to 11e Drive circuit, 12a to 12e Output current detection means, 13a to 13e Output voltage detection means, 14a to 14e Output power detection means, 15a to 15e Load circuit, 16a to 16e Heating Coil, 17a-17e resonant capacitor, 18a-18e clamp diode, 19 control means, 20 load resistance detection means, 22 cooking vessel, 23a-23e input current detection means, 24a-24e input voltage detection means, 101 top plate, 102 body Case, 103 circuit, 104 operation Grower, 105 operation means, 106 heating port.

Claims (4)

A top plate on which a cooking container that is to be heated is placed;
A plurality of heating coils disposed below the top plate and disposed close to one heating port;
A plurality of inverter circuits each supplying high frequency power to a plurality of load circuits having the heating coil;
A power detection means for detecting power respectively output from the plurality of inverter circuits to the plurality of load circuits or power input to the plurality of inverter circuits;
Output current detection means for detecting output current of each of the plurality of inverter circuits;
Load detection means for performing load detection using detection results of the power detection means and the output current detection means;
Control means for driving and controlling the plurality of inverter circuits based on detection results of the power detection means, the output current detection means and the load detection means;
And an operation means for inputting an instruction of heating start / stop and set thermal power, heating mode to the control means,
The load detection means performs load detection as a single energized state for each load circuit,
The induction heating cooker characterized in that the control means includes a heating mode for setting power distribution for each heating coil or each inverter circuit based on the load detection result. A top plate on which a cooking container that is to be heated is placed;
A plurality of heating coils disposed below the top plate and disposed close to one heating port;
A plurality of inverter circuits each supplying high frequency power to a plurality of load circuits having the heating coil;
A power detection means for detecting power respectively output from the plurality of inverter circuits to the plurality of load circuits or power input to the plurality of inverter circuits;
Output current detection means for detecting output current of each of the plurality of inverter circuits;
Load detection means for performing load detection using detection results of the power detection means and the output current detection means;
Control means for driving and controlling the plurality of inverter circuits based on detection results of the power detection means, the output current detection means and the load detection means;
And an operation means for inputting an instruction of heating start / stop and set thermal power, heating mode to the control means,
The load detecting means performs load detection by independently energizing a load circuit having a heating coil adjacent to another heating coil in the load circuit, and for a set of load circuits having heating coils that are not adjacent to each other. Load detection is performed by sequentially energizing a set of load circuits simultaneously.
The induction heating cooker characterized in that the control means includes a heating mode for setting power distribution for each heating coil or each inverter circuit based on the load detection result.   The load detection means performs load detection at predetermined time intervals, and the control means includes a heating mode for setting power distribution for each heating coil or each inverter circuit based on the load detection result. The induction heating cooker according to claim 1 or 2, characterized in that   The induction heating cooker according to any one of claims 1 to 3, wherein the plurality of load circuits include a load circuit having a plurality of heating coils that are not adjacent to each other.

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