JP4821677B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker, and uses a heating coil formed in inner and outer spiral shapes having different diameters arranged substantially concentrically and on the same plane, and the material and size of the object to be heated. The present invention relates to load determination for determining at least one of the above.

Load discrimination in the conventional induction heating cooker uses a plurality of heating coils concentrically wound from the inside to the outside, and sequentially determines the material and size of the object to be heated by switching the heating coil. However, one or a plurality of heating coils are selected and heated according to the material and size of the heated object (see, for example, Patent Document 1).
In addition, in an induction heating cooker having a single heating coil, the material of the object to be heated depends on the current flowing through the damper diode connected in reverse parallel to the switching element of the one-tone voltage resonant inverter and the input current to the inverter. Some have discriminated the size (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 11-224767 (page 9, FIG. 1) Japanese Patent Laid-Open No. 6-168778 (page 7, FIG. 1)

When performing load determination to determine both the material and size of the object to be heated, when performing control to switch a plurality of heating coils sequentially, the electrical circuit becomes large because many parts such as relays are required. There was a problem that the control method was complicated. Furthermore, when a single heating coil is used, there is a problem that the load cannot be accurately determined depending on the position where the object to be heated is placed, that is, when a “pan shift” occurs.
The present invention has been made in order to solve the above-described problems. The first object of the present invention is to increase the accuracy of an electric circuit without increasing the size of an electric circuit, even if a pan shift occurs. Thus, an induction heating cooker capable of determining the load and determining at least one of the material and size of the object to be heated is obtained.

An induction heating cooker according to the present invention includes a smoothing circuit that is connected to a rectifier circuit that full-wave rectifies an alternating current from a power source and smoothes an output voltage of the rectifier circuit, and a plurality of switching elements, and outputs the smoothing circuit. An inverter connected to the stage for converting the output voltage of the smoothing circuit into a high-frequency AC voltage, and connected to the output stage of the inverter, each being arranged on a substantially concentric and substantially coplanar surface that forms a series resonant circuit with a resonant capacitor . A plurality of heating coils formed in spiral shapes with different diameters, coil current detection means for detecting a current flowing in the heating coil side of the heating coils , and an input current for detecting an input current value to the inverter and a detection unit, when determining the material of the object to be heated based on the ratio of the coil current to the input current value, the material of the object to be heated is different inside and outside the vortex diameters Among the heating coil formed by a vapor form, as well as energizing the small heating coil side diameters, connected to the large heating coils in diameter so that the output voltage from the smoothing circuit does not flow through the larger heating coil of diameter Switching the switching element to generate an induction current in the heating coil having a large diameter, and determining based on the induction current value and the input current value detected by the coil current detection means , the ratio of the induction current value to the input current value, When it is larger than the threshold B, the material of the object to be heated is determined as an inappropriate pan that stops the drive of the inverter .

Induction heating cooker of the present invention, since the load determination by using a heating coil formed in diameter arranged in a substantially concentrically and substantially flush with different inside and outside the spiral shape, even if the pot deviation occurs In addition, there is an effect that it is possible to accurately determine the load of the material and size of the heated object. In addition, since load determination is performed only by switching energization of the internal and external heating coils, there is an effect that an easy control method can be used without increasing the size of the electric circuit.

Embodiment 1 FIG.
FIG. 1 shows a circuit configuration diagram of an induction heating cooker according to an embodiment of the present invention. 2 is a drive signal waveform (example) of the full bridge inverter, FIG. 3 is an operation flowchart of the induction heating cooker in the embodiment of the present invention, and FIG. 4 is an experiment conducted by the inventor in the embodiment of the present invention. Mapping diagram of the obtained input current-coil current data (for each pan displacement distance of the object to be heated), FIG. 5 shows the current ratio (= coil current / input current) rewritten on the vertical axis in the data when the pan displacement is 0 mm in FIG. FIG. 6 and FIG. 6 are circuit configuration diagrams when the inverter configuration of FIG. 1 is varied. In FIG. 1 (1), a heating coil 5a having a small diameter (hereinafter referred to as an "inner coil") among the heating coils formed in inner and outer spiral shapes having different diameters arranged substantially concentrically and on the same plane. The resonance capacitor 6a is connected in series with the heating coil 5b having a large diameter (hereinafter referred to as “outer coil”). The outer diameter of the outer coil is formed between 170 mm and 190 mm. The minimum distance between the inner coil 5a and the outer coil 5b is 3-6 mm. The series circuit of the inner coil 5a and the resonant capacitor 6a is connected to the output stage of the full bridge inverter composed of the switching elements 4a, 4b, 4c, 4d, and the series circuit of the outer coil 5b and the resonant capacitor 6b is the switching elements 4a, 4b. 4e and 4f are connected to the output stage of the full bridge inverter. These two full-bridge inverters are connected to the output stage of the smoothing circuit 3 so that current is supplied from the commercial power source 1 via the rectifier circuit 2 and the smoothing circuit 3. The switching elements 4 a to 4 f constituting the inverter are given drive signals from the control means 7 via the drive circuit 9. Here, the control means 7 includes an output of the coil current detection means 12 provided on the series circuit of the inner coil 5a and the resonance capacitor 6a, and an input current detection means 11 provided between the commercial power source 1 and the rectifier circuit 2. And the output of the power setting means 8 for setting the desired power by the user. The output from the control means 7 is connected to the coil energization switching means 10 provided at the output stage of the full bridge inverter.

Note that the input current detection means 11 may be provided at the output stage of the rectifier circuit 2 or the output stage of the smoothing circuit 3 in addition to being provided between the commercial power supply 1 and the rectifier circuit 2.

Next, the operation will be described with reference to FIGS.
A heated body 13 is placed on a top plate (not shown) installed on the upper surface side of the heating coil 5 (inner coil 5a and outer coil 5b), and the user of the induction heating cooker turns on the power to power When the setting is performed (S0), a driving signal is given to each switching element from the control means 7 via the driving circuit 9, and a full bridge inverter operation is performed (S1). Here, at the time of steady operation, the drive signal waveform (example) shown in FIG. 2A is given from the control means 7 so that the full bridge inverter constituted by the switching elements 4a, 4b, 4c and 4d becomes the inner coil 5a. In addition, the full bridge inverter composed of the switching elements 4a, 4b, 4e, and 4f energizes the outer coil 5b. However, when determining the material immediately after the start of heating, a low power setting (for example, about 0.5 kW is input). ), An energization path is formed by the coil energization switching means 10 so that only the inner coil 5a is energized at a frequency (for example, operation at 40 kHz) higher than that during the heating operation (for example, operation at 40 kHz). That is, the series circuit of the inner coil 5a and the resonance capacitor 6a is kept connected to the full bridge inverter, and the series circuit of the outer coil 5b and the resonance capacitor 6b is disconnected from the full bridge inverter. The control means 7 controls the energization switching means 10. After energizing only the inner coil 5a in this way (S2), the input current detecting means 11 detects the input current value (S3), and the coil current detecting means 12 detects the inner coil current value (S4).

With respect to the heated body 13 made of various materials, only the inner coil 5a was measured for the input current value and the inner coil current value when energized, and the following results were obtained. When the measured values of the heated body 13 of various materials are plotted with the input current value on the horizontal axis and the inner coil current value on the vertical axis, the pan deviation is 0 mm (= the heated body 13 is placed at the center position of the heating coil 5. 4), the mapping diagram of FIG. Here, the larger the point, the larger the measured value of the heated object with a larger diameter (the size of the point does not indicate the data distribution, only the size of the heated object) Threshold A] and [Threshold B] are provided for magnetic materials below [Threshold A], non-magnetic materials excluding aluminum between [Threshold A] and [Threshold B], and aluminum materials above [Threshold B]. Can be divided into heated objects. [Threshold A] and [Threshold B] are straight lines representing the ratio between the input current and the coil current, and this measurement is performed when the current ratio (= coil current / input current) is rewritten on the vertical axis as shown in FIG. In the example, the current ratio β ≦ 7.1 can be discriminated from a magnetic material, 7.1 <β <12.5 from a non-magnetic material excluding an aluminum material, and β ≧ 12.5 from an aluminum material.

In addition, when heated objects such as small items (knives, forks, etc.), aluminum mugs, ceramics such as heat-resistant glass pots, earthenware pots, or parts of human or animal bodies are placed In the no-load state where nothing is placed, at least one of the inappropriately heated body and the no-load state can be determined by the [threshold X] in which both the input current value and the inner coil current value are low ( Not shown). The safety can be improved by quickly stopping the inverter according to the determination result.

In addition, when a pan shift occurs (when the center of the position on which the heated body 13 is placed moves relative to the center of the heating coil 5), the heated body of various materials is used. When the measured values in FIG. 13 were plotted, the mapping diagrams shown in FIGS. 4B to 4F were obtained. According to the above material discrimination method, the value of [threshold A] and [threshold B] are up to 100 mm in pan deviation (= the center of the heated body 13 is placed at a distance of 100 mm with respect to the center of the heating coil 5). ] And [Threshold X] (not shown in FIG. 4) can be similarly determined without changing the values.

  In addition, even though the object to be heated was circular but not a circular object such as a square, the value of [Threshold A], the value of [Threshold B], and [Threshold X] against pan deviation Each material can be similarly identified without changing the value of.

The above measurement results are the results when the input current value and the inner coil current value when only the inner coil 5a is energized are measured for the heated body 13 of various materials, but the coil energization switching means 10 is not used. Even when the induced current generated in the outer coil 5b when only the inner coil 5a is energized is measured, the material of the heated body 13 can be similarly determined. Although the value of [Threshold A], the value of [Threshold B], and the value of [Threshold X] change, each material can be similarly identified. When measuring the induced current generated in the outer coil 5b, the coil current detection means 12 in FIG. 1 (1) is moved from the inner coil current measurement position to the outer coil current measurement position between the outer coil 5b and the coil energization switching means 10. The moved circuit configuration diagram of FIG. 1 (2) is used.

Thus, the control means 7 calculates the current ratio (= coil current / input current) obtained from the output of the input current detection means 11 and the output of the coil current detection means 12 (S5), and the calculation result is the control means 7. If the predetermined value A is not less than the predetermined value A stored in advance (S6), the material of the heated body 13 is determined to be a magnetic material (S7), and the calculation result must be not less than the predetermined value A (S6) and not less than the predetermined value B (S8). For example, the material of the body 13 to be heated is determined as a non-magnetic material excluding the aluminum material (S9). If the calculation result is equal to or greater than the predetermined value B (S8), the material of the body 13 to be heated is determined as an aluminum pan (S10). ). The pan made of aluminum means a pan made of at least one of pure aluminum or aluminum alloy. An aluminum pot is called an inappropriate pot. And when the material of the to-be-heated body 13 is discriminate | determined from the pan of an aluminum material (S10), an inverter operation | movement is stopped considering that the improper pan was mounted (S15). Immediately after the steps of S3 and S4, if the calculation result is equal to or less than the predetermined value X, it is determined that the heated body 13 is an inappropriate heated body or a no-load state (S20), and the step of stopping the inverter operation (S15) is inserted. , Increase safety.

  As described above, since the material of the object to be heated is determined by calculating the current ratio between the input current value and the inner coil current value, the material can be determined by an easy control method without increasing the size of the electric circuit. can do. In addition, by providing two predetermined values in the control means 7, it is possible to reliably determine the aluminum material among the non-magnetic materials. Furthermore, since the heating coil is divided into the inner coil and the outer coil, the material can be accurately and reliably discriminated even if the heated object causes a pan shift. Moreover, when it discriminate | determines from the pan of an aluminum material, an improper to-be-heated body, or a no-load state, safety | security can be improved by stopping an inverter rapidly.

By the way, the above material discrimination method is a case where the coil energization switching means 10 is used to control the energization of the outer coil. However, the present invention is not limited to this, and the coil energization switching means 10 is deleted and the inner coil is removed. 5a and one end of the outer coil 5b are connected to the midpoints of the switching elements 4a and 4b, respectively, and the switching elements 4e and 4f are always turned off as shown in FIG. 2B, or as shown in FIG. As shown, the switching element may be normally driven. In the drive waveform of FIG. 2B, “inductive current” flows through the internal diodes of the switching elements 4e and 4f to the outer coil 5b when the inner coil 5a is energized, and in the drive waveform of FIG. 2A, the inner coil 5a is energized. A normal load current also flows through the outer coil 5b, but the present inventor has obtained a measurement result that is not different from the mapping tendency of FIG. 4 in any energization method, and thus obtains the same effect as described above. Can do. In addition, the effect is the same when the full-bridge inverter configuration is changed using eight switching elements as shown in FIG. 6 (however, the switching elements 4e and 4f are always turned off so that the induced current flows through the outer coil 5b). Or the switching elements 4e, 4f, 4g, and 4h are always turned off so that no current flows through the outer coil 5b), and the inverter configuration is a half-bridge inverter configuration (the switching elements 4d and 4f in FIGS. 1 and 6 are always turned on). It should be noted that the effect is the same even in other inverter configurations such as a short circuit and a configuration in which 4c and 4e are always open) and a “single voltage type inverter configuration”.

In the above-described embodiment, the multi-layer coil having different diameters as the heating coil has been described as the inner coil and the outer coil. However, even with a single coil, an intermediate terminal is added and the outer and inner coils can be separately energized. But note that the effect is similar.

In the above-described embodiment, the frequency of energizing the inner coil at the time of material discrimination is higher than the frequency at the time of the heating operation, thereby preventing overcurrent from flowing through the inverter switching element and destroying it. effective. For example, a frequency of 20 kHz is used during the heating operation, and a frequency of 40 kHz is used during material discrimination.

Embodiment 2. FIG.
In the first embodiment described above, the input current value and the inner coil current value are detected by energizing the inner coil, and the material of the object to be heated is discriminated from the current value. An embodiment in which an input current value is detected and the size of the object to be heated is determined from the current value will be described. FIG. 7 is an operation flowchart of the induction heating cooker in such a case, and FIG. 8 is a mapping diagram of input current-coil current data obtained by an experiment by the inventor in this embodiment (pot of heated object) Every deviation distance). In the inverter configuration diagram in this embodiment, the coil current detection means 12 in FIG. 1A described in the first embodiment is changed from the inner coil current measurement position to the outer coil current between the outer coil 5b and the coil energization switching means 10. The description of the circuit configuration in FIG. 1 (2) moved to the measurement position is omitted.

  Next, the operation will be described with reference to FIGS. 1, 2, and 7 to 8. FIG. A heated body 13 is placed on a top plate (not shown) installed on the upper surface side of the heating coil 5 (inner coil 5a and outer coil 5b), and the user of the induction heating cooker turns on the power to power When the setting is performed (S0), a driving signal is given to each switching element from the control means 7 via the driving circuit 9, and a full bridge inverter operation is performed (S1). Here, at the time of steady operation, the drive signal waveform (example) shown in FIG. 2A is given from the control means 7 so that the full bridge inverter constituted by the switching elements 4a, 4b, 4c and 4d becomes the inner coil 5a. In addition, the full bridge inverter composed of the switching elements 4a, 4b, 4e, and 4f energizes the outer coil 5b. However, when determining the pot diameter immediately after the start of heating, a low power setting (for example, 0.5 kW) is used. The coil energization switching means 10 forms an energization path so that only the outer coil 5b is energized at a higher frequency (e.g., operation at 40 kHz) than the heating operation (e.g., operation at 20 kHz). . That is, the series circuit of the inner coil 5a and the resonance capacitor 6a is disconnected from the full bridge inverter, and the series circuit of the outer coil 5b and the resonance capacitor 6b is kept connected to the full bridge inverter. The control means 7 controls the energization switching means 10. After energizing only the outer coil 5b in this way (S11), the input current detecting means 11 detects the input current value (S3).

With respect to the heated body 13 of various materials and sizes, the input current value and the external coil current value when energizing only the outer coil 5b were measured, and the following results were obtained. When the measured values of the heated body 13 of various materials and sizes are plotted on the horizontal axis of the input current value and the vertical axis of the external coil current value, the pan displacement is 0 mm (= the heated body at the center position of the heating coil 5). 13), and in the case of 20 mm, the mapping diagrams of FIGS. 8A and 8B were obtained. Here, the larger the point, the larger the measured value of the object to be heated (the size of the point does not indicate the data distribution, only the size of the object to be heated), as shown in the figure If [threshold C] is provided, for example, if the pan shift is 10% or less of the pan diameter (the heated body 13 is placed at the approximate center position of the heating coil 5), C] Above, it can be divided into heated bodies of large-diameter pans (except for large-diameter pans made of aluminum). In this measurement example, it is possible to discriminate a small-diameter pan with an input current I ≦ 1.1A and a large-diameter pan with an input current I> 1.1A.

Further, when the measured values in the heated body 13 of various materials and sizes when the pan shift occurred, the mapping diagrams shown in FIGS. 8C to 8F were obtained. According to the above-mentioned pan diameter discriminating method, even when a pan shift exceeding 20 mm occurs, if the value of [Threshold C] is not changed, a large-diameter pan is discriminated as a small-diameter pan.

In addition, when heated objects such as small items (knives, forks, etc.), aluminum mugs, ceramics such as heat-resistant glass pots, earthenware pots, or parts of human or animal bodies are placed In the no-load state where nothing is placed, at least one of the inappropriately heated body and the no-load state can be determined by the [threshold value Y] in which both the input current value and the outer coil current value are low ( Not shown). The safety is improved by stopping the inverter promptly according to the determination result.

Thus, if the pan deviation is about 10% or less of the pan diameter (the heated body 13 is placed at the substantially central position of the heating coil 5), the output of the input current detection means 11 is stored in advance by the control means 7. If it is not the predetermined value C or more (S12), the size of the heated body 13 is determined as a small diameter pan (S13), and if the output of the input current detection means 11 is the predetermined value C or more (S12), the size of the heated body 13 is determined. The thickness is determined as a large-diameter pan (S14). However, large-diameter pans made of aluminum are excluded. If the detection result is equal to or less than the predetermined value Y immediately after the step of S3, it is determined that the heated body 13 is an inappropriate heated body or a no-load state (S21), and a step (S15) for stopping the inverter operation is entered to Increases sex.

The above measurement results are the results when the input current value and the external coil current value when only the outer coil 5b is energized are measured for the heated body 13 of various materials and sizes, but only the outer coil 5b is energized. By measuring the induced current generated in the inner coil 5a at the same time, the heated object 13 can be similarly identified as a small-diameter pan or a large-diameter pan. At this time, although the value of [Threshold C] and the value of [Threshold Y] change, the magnitude can be similarly determined. When measuring the induced current generated in the inner coil 5a, the circuit configuration diagram of FIG. 1 (1) in which the coil current detecting means 12 of FIG. 1 (2) is installed at the position of measuring the inner coil current is used.

  As described above, since the size of the object to be heated is determined from the input current value when the outer coil is energized, the size can be controlled by an easy control method without increasing the size of the electric circuit as in the first embodiment. Can be determined. Furthermore, since the heating coil is divided into the inner coil and the outer coil, when the heated object causes a pan shift, the large-diameter pan can be identified as the small-diameter pan. For this reason, when the pan to be heated is large and the heating efficiency is poor, only the inner coil is energized so that power saving and leakage magnetic flux reduction can be realized.

Also in the present embodiment, the configuration is such that the coil energization switching means 10 is deleted as in the first embodiment, and the switching elements 4c and 4d are always turned off as shown in FIG. The switching element may be normally driven as shown in A). In the drive waveform of FIG. 2 (C), “inductive current” flows through the internal diodes of the switching elements 4c, 4d when the outer coil 5b is energized, and in the drive waveform of FIG. 2 (A), the outer coil 5b is energized. A normal load current also flows through the inner coil 5a, but in any energization method, a measurement result almost the same as the mapping tendency of FIG. 8 is obtained, and the same effect as described above can be obtained.

Embodiment 3 FIG.
In contrast to the first and second embodiments described above, this embodiment is a combination of the load determinations of the first and second embodiments.
FIG. 9 is an operation flowchart of the induction heating cooker in such a case.
The inverter configuration diagram in the embodiment of the present invention is FIG. 1 or FIG.

  Next, the operation will be described with reference to FIGS. The energization method in the present embodiment is such that the coil energization switching means 10 is used to energize only the inner coil or only the outer coil, or the coil energization switching means 10 is omitted. A driving waveform shown in FIG. 2B when energized and a driving waveform shown in FIG. 2C when the outer coil is energized are used so that the inner and outer coils are not energized simultaneously.

As in the first embodiment, after energizing only the inner coil 5a (S2), the input current detecting means 11 detects the input current value (S3), and the coil current detecting means 12 detects the inner coil current value ( S4). Since the subsequent operation is the same as in the first embodiment, the description thereof will be omitted. However, if the material of the heated body 13 is determined as a magnetic material (S7), or is determined as a non-magnetic material excluding an aluminum material (S9), As in the second embodiment, only the outer coil 5b is energized (S11), and the input current detecting means 11 detects the input current value (S3). Since the subsequent operation is the same as that of the second embodiment, the description thereof will be omitted. However, if the output of the input current detection means 11 is not equal to or greater than the predetermined value C stored in advance in the control means 7 (S12), the size of the object to be heated 13 Is determined to be a small-diameter pan (S13), and if the output of the input current detection means 11 is equal to or greater than a predetermined value C (S12), the size of the heated body 13 is determined to be a large-diameter pan (S14). On the other hand, when the material of the body 13 to be heated is determined to be an aluminum material (S10), the inverter operation is stopped assuming that an inappropriate pan is placed (S15).

Here, the energization in the present embodiment is the order from the inner coil energization to the outer coil energization. However, this is not restrictive, and the order from the outer coil energization to the inner coil energization may be used (see FIG. 10). That is, it is noted that the order of energization does not matter because the final load discrimination result is the same even if the material discrimination is performed after the pan diameter discrimination.

  As described above, the material of the object to be heated is determined by energizing the inner coil, and then the size of the object to be heated is determined by energizing the outer coil in response to the material determination result, or the object to be heated by energizing the outer coil. Since the body diameter is discriminated, and the material of the heated object is then discriminated by energizing the inner coil, the inverter operation is stopped by reliably determining the aluminum material that is an inappropriate pan for induction heating cookers. In addition, other material discrimination (non-magnetic material excluding magnetic material and aluminum material) and pan diameter discrimination (large-diameter pan and small-diameter pan) can be performed in conjunction with high accuracy. In the case of this embodiment as well, the material and size of the object to be heated can be determined using the induced current generated in the inner coil or the outer coil.

Embodiment 4 FIG.
In contrast to the third embodiment described above, an embodiment in which the inner and outer coils are simultaneously energized will be described. FIG. 11 is an operation flowchart of the induction heating cooker in such a case. Since the inverter configuration diagram in this embodiment is FIG. 1 or FIG. 6 as in the first to third embodiments, the description thereof is omitted.

  Next, the operation will be described with reference to FIGS. In the energization method according to the present embodiment, the coil energization switching means 10 is omitted, and the inner and outer coils are energized at the same time by using the drive waveform shown in FIG. The method.

After energizing the inner coil 5a (S2) and energizing the outer coil 5b (S11), the input current detecting means 11 detects the input current value (S3), and the coil current detecting means 12 detects the inner coil current value. (S4). Next, as in the first embodiment, the material of the heated body 13 is determined from the input current value and the inner coil current value (S5 to S10), and the heated body 13 is determined from the input current value as in the second embodiment. The pot diameter is determined (S12 to S14).

Here, when the material of the to-be-heated body 13 is discriminate | determined from aluminum material (S10), although an inverter operation | movement is stopped considering that the improper pan was mounted (S15), implementation of pan diameter discrimination | determination (S3, S12- S14) If it is determined that the material is aluminum, the inverter operation is stopped.

As described above, since the material and size of the object to be heated are discriminated by energizing the inner coil 5a and energizing the outer coil 5b at the same time, the load discriminating control algorithm becomes easy and the load discriminating time is increased. Has the effect of being short.

Embodiment 5 FIG.
Next, an embodiment in which the heating control is performed by the control means under the heating conditions suitable for the material and size of the object to be heated will be described.
FIG. 12 shows a heating control method (example) for each determined material and size of the object to be heated. In the case of a large-diameter pan made of magnetic material, the inner coil and the outer coil are energized to output 3.0 kW. When using a small-diameter pan made of magnetic material, the inner coil is energized to output 1.5 kW. When using a large-diameter pan made of non-magnetic material (excluding aluminum), the inner coil and outer coil are energized to output 2.0 kW. For small-diameter pans made of non-magnetic material (excluding aluminum), the inner coil is energized to output 1.0 kW. If the pan is made of aluminum, stop the inverter. The inverter is also stopped when using a small-diameter pan made of aluminum. In the case of an inappropriate heating object or no load, the inverter is stopped (not shown in FIG. 12). Further, the inverter configuration diagram in the embodiment of the present invention is FIG. 1 or FIG.

  Next, the operation will be described with reference to FIG. 1, FIG. 2, FIG. 9, and FIG. Based on the first to fourth embodiments, when the material of the heated body 13 is determined to be a magnetic material by the material determination (S7), the size of the heated body 13 is determined to be a large-diameter pan by the size determination. In step S14, the control unit 7 applies the drive waveforms shown in FIG. 2A to the switching elements 4a to 4f, thereby energizing the inner coil 5a and the outer coil 5b, and using the output of the input current detection unit 11. For example, control is performed so as to obtain a heating output of about 3.0 kW at the maximum. On the other hand, if the size of the body 13 to be heated is determined to be a small-diameter pan by size determination (S13), the control means 7 provides the switching waveforms 4a to 4f with the drive waveforms shown in FIG. Control is performed so that only the coil 5a is energized and a heating output of, for example, a maximum of about 1.5 kW is obtained using the output of the input current detection means 11. It is to be noted that energization of only the inner coil 5a is the same even when the coil energization switching means 10 is used. Next, if the material to be heated 13 is determined to be a non-magnetic material (excluding aluminum material) by the material determination (S9), the size of the object to be heated 13 is determined to be a large-diameter pan by the size determination. In step S14, the control unit 7 applies the drive waveforms shown in FIG. 2A to the switching elements 4a to 4f, thereby energizing the inner coil 5a and the outer coil 5b, and using the output of the input current detection unit 11. For example, control is performed so as to obtain a heating output of about 2.0 kW at the maximum. On the other hand, if the size of the body 13 to be heated is determined to be a small-diameter pan by size determination (S13), the control means 7 provides the switching waveforms 4a to 4f with the drive waveforms shown in FIG. Control is performed so that only the coil 5a is energized and a heating output of, for example, a maximum of about 1.0 kW is obtained using the output of the input current detecting means 11. Next, when it is determined that the material of the body 13 to be heated is an aluminum pan (S10), the inverter operation is stopped regardless of the pan diameter (S15). The control means 7 prevents the inner coil 5a and the outer coil 5b from being energized by turning off all the drive signals of the switching elements 4a to 4f. In addition, when it is determined by the load determination that the pot is improper, an improper heated body, or no load state, the control means 7 turns off all the drive signals of the switching elements 4a to 4f by stopping the inverter operation. The coil 5a and the outer coil 5b are not energized.

As described above, since the heating control such as the coil energization method and the heating output according to the load determination result is performed, when the heated object is a non-magnetic material, the heating switching is performed to the switching element of the inverter. Overcurrent can be prevented from flowing and breaking, and when the object to be heated is a small-diameter pan, leakage magnetic flux can be reduced by energizing only the inner coil. Further, there is an effect that power is saved by energizing only the inner coil.

Embodiment 6 FIG.
An embodiment of timing for performing heating control (load discrimination control) again after carrying out load discrimination for discriminating the material and size of an object to be heated will be described. FIG. 13 is an operation flowchart of the induction heating cooker. Since the inverter configuration diagram in the embodiment of the present invention is FIG. 1 or FIG. 6 as in the first to fifth embodiments, the description thereof is omitted.

  Next, the timing operation for carrying out load determination will be described with reference to FIGS. After the induction heating cooker is turned on (S0), a full bridge inverter operation is performed on each switching element by a drive signal from the control means 7 via the drive circuit 9 (S1). The control means 7 performs the load determination control shown in the first to fourth embodiments to determine the material and size of the body 13 to be heated (SS), and performs heating according to the load determination result and the output of the power setting means 8. Output control is performed (S16). Thereafter, when the inverter operating power set by the heating control is changed by a manual operation of the user or an erroneous manual operation of a child or an animal (S17), the control means 7 restarts the inverter (S1), and the load determination control is performed again. (SS), and the heating output control is newly performed in response to the load determination result and the output of the power setting means 8 (S16).

The timing for carrying out the following load determination is also shown. After the power is turned on (S0), the induction heating cooker is given a drive signal from the control means 7 via the drive circuit 9 to each switching element, and a full bridge inverter operation is performed (S1). The control means 7 performs the load determination control shown in the first to fourth embodiments to determine both the material and size of the heated body 13 (SS), and according to the load determination result and the output of the power setting means 8. Heating output control is performed (S16). Thereafter, when the position on which the object to be heated 13 is moved moves with respect to the heating coil 5, a pan shift is detected (S19), the control means 7 restarts the inverter (S1), and the load determination control is performed again. (SS), the heating output control is newly performed in response to the load determination result and the output of the power setting means 8 (S16). As a method of detecting the pan displacement, for example, the following method can be cited. An outer coil current detecting means provided on a series circuit of the outer coil 5b and the resonance capacitor 6b is provided, and it is detected that a pan deviation has occurred when the time deviation of the current phase between the outer coil current and the inner coil current exceeds a predetermined value. To do. Although the above-described method has been described as an example for detecting the pan displacement, it should be noted that there is no problem with another method.

The timing for carrying out the following load determination is also shown. After the power is turned on (S0), the induction heating cooker is given a drive signal from the control means 7 via the drive circuit 9 to each switching element, and a full bridge inverter operation is performed (S1). The control means 7 performs the load determination control shown in the first to fourth embodiments to determine both the material and size of the heated body 13 (SS), and according to the load determination result and the output of the power setting means 8. Heating output control is performed (S16). Load determination is performed at any time during the heating from the heating output control (after a certain period of time or after a certain period of time) (S18). If there is a difference from the initial load determination value, the control means 7 restarts the inverter (S1), performs load determination control again (SS), receives the load determination result and the output of the power setting means 8, and newly heats it. Output control is performed (S16).

  As described above, after performing the load determination for determining the material and size of the object to be heated, the timing for performing the load determination again is determined by whether the inverter operating power set by the heating control is manually operated by the user or the child or animal It is assumed that it has been changed due to an erroneous manual operation such as, or that it has been detected that a pan slip has occurred. The load determination is performed again at any time during the heating output control. The heating control can be performed by safe and optimal inverter operation in accordance with a change in inverter operating power setting, a change in a heated object, or a change in a load determination value.

Embodiment 7 FIG.
Next, an embodiment for displaying a load discrimination result (material discrimination, pan diameter discrimination) will be shown.
After discrimination (embodiment discrimination of material and discrimination of pan diameter) in Embodiments 1 to 6 in this invention, the discrimination result is displayed on the induction heating cooker body.
FIG. 14 shows an overall view of the induction heating cooker, and circles 15a and 15b indicating the positions of the heating coils are shown on the upper surface. The distance between the centers of the circles 15a and 15b indicating the position of the heating coil is, for example, 290 mm to 310 mm. The display surface 16a which displays the discriminated result on the upper surface of the induction heating cooker and the display surface 16b which is displayed on the side surface are shown. The display surface 16 is provided on at least one of the upper surface and the side surface of the induction heating cooker.

  Next, the operation will be described with reference to FIG. 3, FIG. 7, FIG. 9, FIG. 10, FIG. In the operation flowchart, the material of the pan is determined (S7), (S9), (S10), and the diameter of the pan is determined (S13). (For example, “magnetic material”, “non-magnetic material”, “aluminum material”, etc.) are displayed on the display surface 16a and the display surface 16b (S23 not shown).

  As a method of displaying the determined result, a method using an LED has been shown as an example. However, a liquid crystal, a fluorescent lamp, or the like may be used as long as the determined result can be displayed. Further, the determined result may be indicated by a sound such as an electronic sound. It should be noted that the effect is the same if it is at least one of display and sound.

  As described above, by displaying the determined result, the user should take appropriate measures such as stopping the induction heating cooker immediately when the inappropriate heating target is on the induction heating cooker. I can do it. Moreover, when the pan shift is large, there is an effect that the pan position can be quickly returned to the correct position.

Embodiment 8 FIG.
In the embodiment as described above, the input current and the load current (inner coil current, outer coil current) are detected and the load determination is performed. However, the present embodiment shows the detected input current value, The coil current value is not used as it is, but the input current detection voltage (at least one of the inner coil and the outer coil is energized, and the voltage converted by the control means 7 from the input current obtained by the input current detection means 11 is hereinafter referred to as “input current detection. From the inner coil current detection voltage (the voltage value obtained by converting the output current of the input current detection means 12 of the inner coil by the control means 7 is referred to as “inner coil current detection voltage”), That is, it is determined whether or not the object to be heated is placed on a top plate (not shown) provided above the heating coil.
Figure 15 is a circuit diagram of the induction heating cooker of this embodiment, FIG. 16 is the operation flow chart of the induction heating cooker, Fig. 17, the present inventor in the present embodiment is obtained by experiments, various It is a mapping figure of the input current detection voltage-inner coil current detection voltage measured value data of the to-be-heated body 13 of a material and a pan diameter, and shows (A)-(F) for every pan deviation distance. Figure 18 is an input current detection voltage obtained by the present inventors have experimentally in this embodiment - a mapping diagram of the inner coil current detection voltage data, the diagram of FIG. 18 for each power supply voltage (A) ~ (F) Show. In FIG. 17, power supply voltage detection means 17 is connected to the output of the rectifier circuit 2 in order to detect the output voltage of the rectifier circuit 2. In addition to this, the connection position of the power supply voltage detection means 17 may be the output of the smoothing circuit 3. Note that the same reference numerals are given to the same parts as those of the above-described embodiment, and the description thereof is omitted.

Next, the operation will be described with reference to FIGS. The operations from S0 to S2 in FIG. 16 are the same as those in the first embodiment, and a description thereof will be omitted.
In the present embodiment, the output of the input current detection means 11 is an input current detection voltage value obtained by converting the current by the control means 7 (S31). Similarly, the output of the coil current detection means 12 is set to the inner coil current detection voltage value obtained by converting the current by the control means 7 (S41).

For the heated body 13 of various materials and sizes, the input current detection voltage value and the inner coil current detection voltage value when only the inner coil 5a was energized were measured, and the following results were obtained. In the case of a power source voltage of 200 V and a pan displacement of 0 mm (= the heated body 13 is placed at the center position of the heating coil 5), the mapping diagram of FIG. If a [threshold X] (filled area in the figure) defined by the input current detection voltage value and the inner coil current detection voltage value is provided as shown in the figure, there is no load (knife, fork, etc.) within the [threshold X] region. In other words, it can be classified into a loaded state outside the area of [threshold X]. In this measurement example, it can be determined that there is no load when the input current detection voltage is 0.25 V or less and the inner coil current detection voltage is 1.0 V or less, and there is a load other than that. When it is determined that there is no load, safety can be improved by quickly stopping the inverter (S15).

Moreover, when the pan shift occurred when the power source voltage was 200 V, the measured values in the heated body 13 of various materials and sizes were plotted, and mapping diagrams shown in FIGS. 17B to 17F were obtained. According to the method for determining whether or not there is a load, if the value of [Threshold X] is not changed, if there is a pan shift exceeding 40 mm, it is determined that there is no load even if there is a load. Since it can be determined that there is no load, the inverter can be stopped quickly and safety can be improved.

Next, when the power supply voltage fluctuates when the pan deviation is 0 mm, the input current detection voltage value and the internal coil current detection voltage value when the inner coil 5a is energized are measured for the heated body 13 of various materials and sizes. Thus, the mapping diagrams of FIGS. 18 (A) to (E) were obtained. As shown in the figure, the [threshold X] (filled portion in the figure) defined by the input current detection voltage value and the inner coil current detection voltage value is changed according to the output (S24) of the power supply voltage detection means 17 (S25). Thus, it is possible to accurately determine the presence or absence of a load even when the power supply voltage fluctuates. In this measurement example, the threshold of the input current detection voltage and the threshold of the inner coil current detection voltage are changed according to the power supply voltage as shown in Table 1.

Thus, the object to be heated 13 is not placed unless both the output of the input current detection means 11 and the output of the coil current detection means 12 are equal to or greater than the threshold value X stored in advance by the control means 7 (S22). Load state) and discrimination (S23), and if both or one of the output of the input current detection means 11 and the output of the coil current detection means 12 is equal to or greater than the threshold value X (S22), it is determined that the heated object 13 is placed. To do. The threshold value X is changed according to the power supply voltage value (S24) (S25).

  As described above, since the presence / absence of the object to be heated is determined by providing the threshold value based on the input current detection voltage value and the inner coil current detection voltage value, an easy control method without increasing the size of the control means 7 It is possible to determine the presence or absence of a load. Furthermore, since this threshold value is changed according to the power supply voltage value, accurate and reliable determination can be performed even when the power supply voltage fluctuates. Also, when it is determined that there is no load, safety can be improved by quickly stopping the inverter.

Embodiment 9 FIG.
In the above-described eighth embodiment, the presence or absence of the object to be heated is determined from the input current detection voltage value by the inner coil energization and the inner coil current detection voltage value. In energization, the input current detection voltage value and the outer coil current detection voltage value (the voltage value obtained by converting the output current of the input current detection means 12 of the outer coil by the control means 7 is referred to as “outer coil current detection voltage”) to be heated. It is to determine the size of the body.
Figure 19 is a circuit diagram of the induction heating cooker of this embodiment, FIG. 20 is the operation flow chart of the induction heating cooker, Fig. 21, the present inventor in the present embodiment is obtained by experiments, various It is a mapping figure of the input electric current detection voltage-outer coil electric current detection voltage measured value data of the to-be-heated body 13 of a material and a pan diameter, and shows (A)-(F) for every pan deviation distance. FIG. 22 is a mapping diagram in which the relationship between the input current detection voltage and the outer coil current detection voltage data obtained by the inventors in this embodiment is plotted. FIG. 22A to FIG. ). In FIG. 19, power supply voltage detection means 17 is connected to the output of the rectifier circuit 2 in order to detect the output voltage of the rectifier circuit 2. In addition to this, the connection position of the power supply voltage detection means 17 may be the output of the smoothing circuit 3. Note that the same reference numerals are given to the same parts as those of the above-described embodiment, and the description thereof is omitted.

Next, the operation will be described with reference to FIGS. The operations in S0, S1, and S11 in FIG. 20 are the same as those in the first embodiment, and a description thereof is omitted.
Also in the present embodiment, the output of the input current detection means 11 is set to the input current detection voltage value obtained by converting the current by the control means 7 (S31). Similarly, the output of the coil current detection means 12 is set to the outer coil current detection voltage value obtained by converting the current by the control means 7 (S42).

For the heated body 13 of various materials and sizes, the input current detection voltage value and the outer coil current detection voltage value when only the outer coil 5b was energized were measured, and the following results were obtained. In the case of a power source voltage of 200 V and a pan shift of 0 mm (= the heated body 13 is placed at the center position of the heating coil 5), the mapping diagram of FIG. If a [threshold C] defined by the input current detection voltage value and the outer coil current detection voltage value is provided as shown in the figure, the pan deviation is, for example, 10% or less of the pan diameter (the object to be heated at the approximate center position of the heating coil 5) 13), within the area of [Threshold C] (S26), the small-diameter pan (S13), and outside the area of [Threshold C] (S26), the large-diameter pan (S14) can be classified. . In this measurement example, a small-diameter pan can be discriminated from an input current detection voltage of 0.27 V or less and an outer coil current detection voltage of 1.4 V or less.

Further, when the measured values in the heated body 13 of various materials and sizes when the pan shift occurred when the power source voltage was 200 V, mapping diagrams shown in FIGS. 21B to 21F were obtained. According to the pan diameter discriminating method described above, when the value of [Threshold C] is unchanged, when a pan shift exceeding 20 mm occurs, a large-diameter pan is discriminated as a small-diameter pan.

Next, when the power supply voltage fluctuates when the pan deviation is 0 mm, the input current detection voltage value and the outer coil current detection voltage value when only the outer coil 5 b is energized are measured for the heated body 13 of various materials and sizes. 22A to 22E were obtained. By changing the [threshold C] defined by the input current detection voltage value and the outer coil current detection voltage value according to the output (S24) of the power supply voltage detection means 17 (S27) as shown in FIG. Even if you get up, you can accurately determine the pot diameter. In this measurement example, the threshold of the input current detection voltage and the threshold of the outer coil current detection voltage are changed according to the power supply voltage as shown in Table 2.

Thus, if both the output of the input current detection means 11 and the output of the coil current detection means 12 are not less than the threshold C stored in advance in the control means 7 (S26), the size of the heated body 13 is determined as a small diameter pan. (S13) If both or one of the output of the input current detection means 11 and the output of the coil current detection means 12 is equal to or greater than the threshold C (S22), the size of the heated body 13 is determined as a large-diameter pan (S14). . The threshold C is changed according to the power supply voltage value (S24) (S25).

As described above, since the size of the object to be heated is discriminated from the input current detection voltage value when the outer coil is energized and the outer coil current detection voltage value, the control means 7 is made large as in the first embodiment. The size can be discriminated by an easy control method without making it. Moreover, since the heating coil is divided into the inner coil and the outer coil, when the heated object causes a pan shift, the large-diameter pan can be identified as the small-diameter pan. Therefore, when the pan of the object to be heated is large and the heating efficiency is poor, the power can be saved and the leakage magnetic flux can be reduced by energizing only the inner coil.
Furthermore, since this threshold value is changed according to the power supply voltage value, it is possible to accurately and reliably discriminate the pot diameter even when the power supply voltage fluctuates.

Embodiment 10 FIG.
In Embodiment 9 described above, the input current detection voltage value and the outer coil current detection voltage value are detected by energization of the outer coil, and the size of the object to be heated is determined from the detected voltage value. Next, an embodiment in which the input current detection voltage value and the outer coil current detection voltage value are detected by energizing the outer coil and the material of the object to be heated is discriminated from the detected voltage value will be described.
Figure 23 is a flowchart of the induction heating cooker of this embodiment, FIG. 24, the present inventor in the present embodiment was obtained in the experiment various materials, the input current detection of the object to be heated 13 Nabe径FIG. 24 is a mapping diagram of voltage-outer coil current detection voltage measurement value data, and FIGS. 24A to 24F are shown for each pan displacement distance. Figure 25 is an input current sense voltage present inventors in this embodiment is obtained in Experiment - a mapping diagram of the outer coil current detection voltage data shows a diagram 25 (A) ~ (F) for each power supply voltage.
In addition, FIG. 19 is diverted for the circuit block diagram of this induction heating cooking appliance.

Next, the operation will be described with reference to FIGS. The operations in S0, S1, and S11 in FIG. 23 are the same as those in the first embodiment, and a description thereof is omitted.
Also in the present embodiment, the output of the input current detection means 11 is set to the input current detection voltage value obtained by converting the current by the control means 7 (S31). Similarly, the output of the coil current detection means 12 is set to the outer coil current detection voltage value obtained by converting the current by the control means 7 (S42).

For the heated body 13 of various materials and sizes, the input current detection voltage value and the outer coil current detection voltage value when only the outer coil 5b was energized were measured, and the following results were obtained. In the case of a pan displacement of 0 mm at the power supply voltage of 200 V (= the heated body 13 is placed at the center position of the heating coil 5), the mapping diagram of FIG. If [Threshold A] and [Threshold B] defined by the input current detection voltage value and the outer coil current detection voltage value are provided as shown in the figure, the magnetic material (S7), [Threshold A] It can be classified into a non-magnetic material (S9) excluding an aluminum material between [threshold B] and an object to be heated of aluminum material (S10) above [threshold B]. Here, [Threshold A] and [Threshold B] are straight lines representing the ratio between the input current detection voltage and the outer coil current detection voltage, respectively. In this measurement example, the detection voltage ratio β ≦ 4.1 and the magnetic material 4.1 <β < It can be distinguished from non-magnetic material except aluminum material at 5.5, and aluminum material at β ≧ 5.5.

Moreover, when the pan shift occurred when the power source voltage was 200 V, the measured values in the heated body 13 of various materials and sizes were plotted, and the mapping diagrams shown in FIGS. 24B to 24F were obtained. According to the above material discrimination method, the value of [threshold A] and [threshold B] are up to 100 mm in pan displacement (= the center of the heated object 13 is placed at a distance of 100 mm with respect to the center of the heating coil 5). Each material can be similarly identified without changing the value of].

Next, when the power supply voltage fluctuates when the pan deviation is 0 mm, the input current detection voltage value and the outer coil current detection voltage value when only the outer coil 5 b is energized are measured for the heated body 13 of various materials and sizes. 25A to 25E were obtained. As shown in the figure, among [Threshold A] and [Threshold B] defined by the input current detection voltage value and the outer coil current detection voltage value, only [Threshold A] is determined according to the output (S24) of the power supply voltage detection means 17. By changing (S30), it is possible to accurately determine the material of the pan even if the power supply voltage fluctuates. In this measurement example, the detection voltage ratio of [Threshold A] is changed according to the power supply voltage as shown in Table 3.

Thus, the control means 7 calculates the detection voltage ratio (= outer coil current detection voltage / input current detection voltage) obtained from the output of the input current detection means 11 and the output of the coil current detection means 12 (S5). If the calculation result is not more than the threshold A stored in advance in the control means 7 (S28), the material of the heated body 13 is determined as a magnetic material (S7), the calculation result is not less than the threshold A (S28) and not less than the threshold B (S29). If not, the material of the heated body 13 is determined as a non-magnetic material excluding the aluminum material (S9). If the calculation result is equal to or greater than the threshold value B (S29), the material of the heated body 13 is determined as an aluminum pan. (S10). An aluminum pan is a pan made of pure aluminum or aluminum alloy. The threshold A is changed according to the power supply voltage value (S24) (S30). When the material of the heated body 13 is determined to be an aluminum pan (S10), the inverter operation is stopped assuming that an inappropriate pan is placed (S15).

As described above, since the material of the object to be heated is determined by calculating the detection voltage ratio between the input current detection voltage value and the outer coil current detection voltage value, the control means 7 is the same as in the ninth embodiment. The material can be identified by an easy control method without increasing the size. Further, by providing two predetermined values in the control means 7, it is possible to reliably determine the aluminum material among the non-magnetic materials. In addition, since the heating coil is divided into an inner coil and an outer coil, the material can be accurately and reliably discriminated even if the object to be heated causes a pan shift. In addition, when it is determined that the pan is made of aluminum, safety can be improved by quickly stopping the inverter.
Furthermore, since one of the threshold values is changed according to the power supply voltage value, it is possible to accurately and reliably discriminate the pot material even when the power supply voltage fluctuates.

Embodiment 11 FIG.
In contrast to the above-described eighth, ninth, and tenth embodiments, the present embodiment combines the load determination in the eighth, ninth, and tenth embodiments.
FIG. 26 is a circuit configuration diagram of the induction heating cooker according to the eleventh embodiment, and FIG. 27 is an operation flowchart of the induction heating cooker.
Note that the same parts as those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  Next, the operation will be described with reference to FIGS. As in the eighth embodiment, after energizing only the inner coil 5a (S2), the input current detection means 11 detects the input current detection voltage value (S31), and the coil current detection means 12a detects the inner coil current detection voltage value. Is detected (S41). Since the subsequent operation is the same as that in the eighth embodiment, the description thereof will be omitted. However, the output of the input current detecting means 11 and the output of the coil current detecting means 12a are outside the threshold value X area stored in advance in the control means 7 (S22). If there is, it is determined that the heated body 13 is placed on a top plate (not shown). Next, as in the ninth embodiment, only the outer coil 5b is energized (S11), the input current detection means 11 detects the input current detection voltage value (S31), and the coil current detection means 12b is the outer coil current detection voltage. A value is detected (S42). Since the subsequent operation is the same as that of the ninth embodiment, the description thereof will be omitted. However, the output of the input current detection means 11 and the output of the coil current detection means 12b are outside the threshold C area stored in advance in the control means 7 (S26). If not, the size of the heated body 13 is determined as a small-diameter pan (S13), and if it is outside the threshold C region (S26), the size of the heated body 13 is determined as a large-diameter pan (S14). When only the outer coil 5b is energized (S11), the input current detection means 11 detects the input current detection voltage value (S31), and the coil current detection means 12b detects the outer coil current detection voltage value (S42). As in the tenth embodiment, when the detection voltage ratio of the input current and the coil current is equal to or less than the threshold A, the material of the heated body 13 is determined as a magnetic material (S7), and the aluminum material is excluded between the threshold A and the threshold B. It is determined that the material is a non-magnetic material (S9). If it is determined that the material is aluminum, the inverter operation is stopped assuming that an inappropriate pan is placed (S15).

Further, by changing the threshold value X, threshold value C, and threshold value A according to the detected value (S24) of the power supply voltage (S25, S27, S30), accurate determination can be made even when the power supply voltage fluctuates.

Here, the energization in the present embodiment is the order from the inner coil energization to the outer coil energization. However, the order is not limited to this, and the order from the outer coil energization to the inner coil energization may be used. That is, it is noted that even if the pan presence / absence discrimination is performed after the pan diameter discrimination and the pan material discrimination, the final load discrimination result is the same, so the order of energization does not matter.

  As described above, the presence / absence determination of the object to be heated is performed by energizing the inner coil, and then the size and material of the object to be heated are determined by energizing the outer coil based on the result of the presence / absence determination, or The size and material of the heating element are determined, and then the presence or absence of the object to be heated is determined by energizing the inner coil. Can be stopped, and other material discrimination (non-magnetic material excluding magnetic material and aluminum material) and pan diameter discrimination (large-diameter pan and small-diameter pan) can be performed in conjunction with high accuracy.

Embodiment 12 FIG.
Next, an embodiment in the case where a plurality of switching elements constituting the inverter are housed in one module (power module) will be described.
The inverter configuration in FIG. 1 is a circuit configuration diagram using six switching elements (IGBTs, etc.) 4a to 4f. However, in the embodiment, a configuration in which these six switching elements are configured by discrete components is used. The configuration is changed to an IPM (Intelligent Power Module) with a switching element. As a result, reliability is improved by improving noise resistance, and workability is improved by reducing the number of parts.

  As an application example of the present invention, there is an induction heating cooker that performs load discrimination using a heating coil formed in an inner and outer spiral shape.

Is a circuit diagram of an induction heating cooker showing the a form 1 of implementation and the second embodiment. It is an explanatory view showing a driving signal waveform (example) of the full bridge inverter shown in the form 1 of implementation. An operation flowchart of the induction heating cooker showing Embodiment 1 of implementation. Input current inventors in the form 1 of implementation is obtained in Experiment - is a mapping diagram of the coil current data (each pot deviation distance object to be heated). FIG. 5 is a diagram in which the current ratio (= coil current / input current) is rewritten on the vertical axis in the data when the pan deviation is 0 mm in FIG. 4. It is a circuit block diagram at the time of making the inverter structure of FIG. 1 different. An operation flowchart of the induction heating cooker showing Embodiment 2 of implementation. Input current inventors in the implementation of Embodiment 2 was obtained in the experiment - is an explanatory view showing mapping diagram of the coil current data (each pot deviation distance object to be heated). An operation flowchart of the induction heating cooker showing Embodiment 3 of implementation. 10 is an operation flowchart in the case where the order of the outer coil energization and the inner coil energization is reversed in FIG. 9. An operation flowchart of the induction heating cooker showing a fourth implementation. A heating control method for each material and the size of the object to be heated (eg) indicating the fifth implementation. An operation flowchart of the induction heating cooker showing a sixth implementation. It is an explanatory view of an induction heating cooker showing a seventh implementation. It is a circuit diagram of an induction heating cooker showing the eighth implementation. An operation flowchart of the induction heating cooker showing the eighth implementation. Input current detection voltage present inventors in the implementation of embodiment 8 were obtained in the experiment - a mapping diagram of the inner coil current detection voltage data. (Draw (A) to (F) for each pan shift distance) Input current detection voltage present inventors in the implementation of embodiment 8 were obtained in the experiment - a mapping diagram of the inner coil current detection voltage data. (Draw (A) to (F) for each power supply voltage) It is a circuit diagram of an induction heating cooker showing the ninth implementation. An operation flowchart of the induction heating cooker showing the ninth implementation. Input current detection voltage present inventors have obtained in Experiment in the implementation of embodiment 9 - is a mapping diagram of the outer coil current detection voltage data. (Draw (A) to (F) for each pan shift distance) Input current detection voltage present inventors have obtained in Experiment in the implementation of embodiment 9 - is a mapping diagram of the outer coil current detection voltage data. (Draw (A) to (F) for each power supply voltage) An operation flowchart of the induction heating cooker showing a tenth implementation. Input current detection voltage present inventors have obtained in Experiment in the form 10 of the implementation - a mapping diagram of the outer coil current detection voltage data. (Draw (A) to (F) for each pan shift distance) Input current detection voltage present inventors have obtained in Experiment in the form 10 of the implementation - a mapping diagram of the outer coil current detection voltage data. (Draw (A) to (F) for each power supply voltage) It is a circuit diagram of an induction heating cooker showing the eleventh implementation. An operation flowchart of the induction heating cooker showing the eleventh implementation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Commercial power supply, 2 Rectifier circuit, 3 Smoothing circuit, 4a-4d Switching element, 5a Heating coil (inner coil), 5b Heating coil (outer coil), 6a Resonance capacitor (for inner coil), 6b Resonance capacitor (for outer coil) ), 7 control means, 8 power setting means, 9 drive circuit, 10 coil energization switching means, 11 input current detection means, 12 coil current detection means, 13 object to be heated, 14 induction heating cooker, 15a position of heating coil Circle (right side), 15b Circle (left side) showing the position of the heating coil, 16a Discrimination result display surface (upper surface side), 16b Discrimination result display surface (side surface side), 17 Power supply voltage detection means.

Claims (3)

A smoothing circuit connected to a rectifying circuit for full-wave rectification of an alternating current from a power source, and smoothing an output voltage of the rectifying circuit;
An inverter configured by a plurality of switching elements and connected to an output stage of the smoothing circuit to convert the output voltage of the smoothing circuit into a high-frequency AC voltage;
A plurality of heating coils connected to the output stage of the inverter, each formed in a spiral shape having different diameters arranged substantially concentrically and substantially on the same plane to form a series resonance circuit together with a resonance capacitor ;
Among the heating coils , coil current detection means for detecting a current flowing on the heating coil side having a large diameter ,
An input current detecting means for detecting an input current value to the inverter;
When determining the material of the object to be heated based on the ratio of the coil current value to the input current value ,
Among the heating coils formed in inner and outer spiral shapes having different diameters, the material to be heated is energized to the heating coil side having a smaller diameter, and the output voltage from the smoothing circuit has a larger diameter. Switching the switching element connected to the heating coil having a large diameter so as not to flow to the side to generate an induction current in the heating coil having a large diameter, and the induced current value detected by the coil current detecting means and Determine based on the input current value,
When the ratio of the induction current value to the input current value is greater than a predetermined value B, the material of the heated object is determined as an inappropriate pan that stops driving the inverter . . When the input current value and the induced current value are smaller than a predetermined value X , it is determined that the heated body is an inappropriate heated body that stops driving the inverter or is in an unloaded state. Item 2. An induction heating cooker according to item 1. When determining the material of the heated object ,
The induction heating cooker according to claim 1 or 2 , wherein a frequency of energizing the heating coil having a small diameter is set higher than a frequency during a heating operation.

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