JP5506609B2 - Induction heating cooker and control method thereof - Google Patents

Description

  The present invention relates to an induction heating cooker and a control method thereof, and relates to an induction heating cooker having a plurality of heating coils for heating a single heated body (pan) and a control method thereof.

  So far, induction heating cookers that heat a single pan using a plurality of heating coils have been proposed that arbitrarily control the amount of power supplied to each heating coil. For example, the induction heating cooker described in Patent Document 1 has a heating coil disposed in the center and a small heating coil group disposed in the vicinity of the heating coil, and includes a central heating coil and a small heating coil group. By individually supplying power, a large pan having a bottom size larger than the outer diameter size of the central heating coil is heated uniformly and without impairing the cooking performance.

JP 2010-73384 A

  However, according to the induction heating cooker of Patent Document 1, the amount of power supplied to the central heating coil (the product of power and time during heating), and the amount of power supplied to each of the small heating coil groups, The ratio between is preset. Therefore, the structure including the material and shape of the heated object (pan) is not uniform, and there is a part that is difficult to be heated, or because the heat radiation in the peripheral part (near the side wall) of the heated object is large, When only the central part is heated intensively, the food contained in the object to be heated cannot be heated uniformly, which may cause uneven heating and scorching, and optimal heating of the food May interfere.

  Therefore, the entire heated body (pan bottom) is uniform regardless of the configuration including the material and shape of the heated body, and regardless of the specific heating characteristics (ease of heating) according to the area of the heated body (pan bottom). It is strongly desired to realize an induction heating cooker that can be heated rapidly.

Accordingly, the present invention has been made to solve the above-described problems, and the induction heating cooker includes at least one central heating coil for heating a single object to be heated and a plurality of peripherals arranged around the central heating coil. A heating coil, a central driving circuit and a plurality of peripheral driving circuits for supplying a high-frequency current independently to the central heating coil and the peripheral heating coils, and a central driving current detection for detecting a central driving current flowing in the central heating coil A plurality of peripheral drive current detection means for detecting peripheral drive currents flowing through the peripheral heating coils; central drive voltage detection means for detecting a central drive voltage applied to both ends of the central heating coil; and a plurality of peripheral driving voltage detecting means for detecting the peripheral drive voltage applied across the peripheral heating coil, said central driving circuit and the respective peripheral driving circuits A control circuit for standing and controlling, and at least one temperature detecting means for detecting the temperature of the object to be heated, wherein the control circuit supplies the predetermined heating power to the central heating coil. When the drive circuit is controlled, a central time change rate (dT ₁ / dt) of the temperature (T) of the heated object detected by the temperature detecting means is calculated, and a predetermined judgment power is applied to each peripheral heating coil. When each of the peripheral driving circuits is controlled so as to supply a quantity, a plurality of peripheral time change rates (dT ₂ / dt, dT _i / dt) of the temperature (T) of the heated object detected by the temperature detecting means , I is a natural number of 3 or more)
The control circuit includes a central driving power amount (Q ₁ ) supplied to the central heating coil, and a plurality of peripheral driving power amounts (Q ₂ ,..., Q _i ) supplied to the peripheral heating coils. Ratio (Q ₁ / Q ₂ ,..., Q ₁ / Q _i ) is the central time change rate (dT ₁ / dt) and the respective peripheral time change rates (dT ₂ / dt,..., DT). _i / dt) to control the central driving circuit and the peripheral driving circuits so that the control circuit controls the high frequency current to the central heating based on the central driving current and the central driving voltage. It is determined whether or not the coil should be supplied, and based on the peripheral drive current and the peripheral drive voltage, it is determined whether or not a high frequency current should be supplied to each peripheral heating coil, and the high frequency current should not be supplied Said ambient heating determined Based on the temperature (T) of the object to be heated detected by the ambient temperature sensor which is not adjacent to the-yl, central time change rate (dT 1 / _dt) and a plurality of peripheral temporal change rate (dT 2 / _dt, ··· , DT _i / dt, i is a natural number of 3 or more) .

  According to the induction heating cooker of the present invention, regardless of the configuration including the material and shape of the object to be heated, and regardless of the specific heating characteristics (ease of heating) depending on the region of the object to be heated (pan bottom) By heating the whole body uniformly, it is possible to suppress the occurrence of uneven heating and scorching.

It is a schematic perspective view which shows the whole induction heating cooking appliance which concerns on this invention. It is the partially broken top view which abbreviate | omitted a part of top plate shown to the induction heating cooking appliance of FIG. 1, and looked at the internal structure of the IH heating part from the top. FIG. 3 is a vertical cross-sectional view of an IH heating unit as seen from line III-III in FIG. 2. 4 is a circuit block diagram showing an electric circuit unit for driving and controlling the IH heating unit according to Embodiment 1. FIG. It is a waveform diagram of the drive voltage and drive current detected by the drive voltage detection circuit and the drive current detection circuit. It is a graph which shows the relationship between the resonant frequency Fr and load resistance R when the pan which consists of various component materials is detected by changing the area superimposed on a heating coil. It is a timing chart which shows the control method which concerns on Embodiment 1, Comprising: The time transition of the driving electric power output from each drive circuit and the surface temperature of a pan is shown. It is a timing chart which shows another control method which concerns on Embodiment 1, Comprising: The determination power and drive power which are output from each drive circuit, and the time transition of the surface temperature of a pan are shown. 6 is a plan view showing an IH heating unit according to Modification 1 of Embodiment 1. FIG. It is the top view which looked at the IH heating part concerning Embodiment 2 from the top. It is a timing chart which shows the control method which concerns on Embodiment 2, Comprising: The determination electric power and drive electric power which are output from each drive circuit, and the time transition of the surface temperature of a pan are shown. (A) shows the state where the pan deviated from the central position above the IH heating unit according to Embodiment 1, and (b) is a schematic diagram showing the state where the oblong pan was placed. It is. (A) shows the state where the pan deviated from the central position above the IH heating unit according to the second embodiment, and (b) is a schematic diagram showing the state where the oblong pan was placed. It is. FIG. 10 is a plan view showing an IH heating unit according to a second modification of the second embodiment. (A) shows the state by which the pan deviated from the center position above the IH heating part which concerns on the modification 2 of Embodiment 2, (b) shows the state by which the ellipse pan was mounted. FIG. FIG. 11 is a plan view showing an IH heating unit according to Modification 3 of Embodiment 2. It is a timing chart which shows the control method which concerns on the modification 4 of Embodiment 2, Comprising: The determination power and drive power which are output from each drive circuit, and the time transition of the surface temperature of a pan are shown.

  Embodiments of an induction heating cooker according to the present invention will be described below with reference to the accompanying drawings. In the description of each embodiment and the attached drawings below, the same components are referred to by the same reference numerals.

Embodiment 1 FIG.
The first embodiment of the induction heating cooker according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a perspective view schematically illustrating the entire induction heating cooker 1 according to the present invention. An induction heating cooker 1 shown in FIG. 1 includes an outline, a casing 2, a top plate 3 formed of glass or the like that covers substantially the entire upper surface thereof, a pair of IH heating units 10 and 11 arranged on the left and right sides, and a center. A central heating unit 4 and a cooking grill 5. The central heating unit 4 may adopt any heating method of IH method or radiant method.

In the specification of the present application, the present invention will be described below with reference to the IH heating unit 10 shown on the left side of FIG. 1, but the IH heating unit 11 shown on the right side and the central heating unit 4 when the IH system is adopted are also described. Similarly, the present invention can be applied.
Moreover, in this specification, although the induction heating cooking appliance 1 which has what is called a center grille structure in which the cooking grill 5 is arrange | positioned in the approximate center of the housing | casing 2 is demonstrated exemplarily, this invention is limited to this. However, the present invention can also be applied to an induction heating cooker in which the cooking grill 5 is biased to one of the side surfaces (having a side grill structure) or an cooking cooker that does not include the cooking grill.

  The induction heating cooker 1 is operated so that the user adjusts the heating power of the IH heating units 10 and 11 and the central heating unit 4, and an operation display unit (liquid crystal display touch panel) 6a for displaying these control states. 6b, 6c. The induction heating cooker 1 has a pair of intake windows 7 a and 7 b and an exhaust window 8 provided on the rear side of the top plate 3.

  FIG. 2 is a partially cutaway plan view of the internal structure of the IH heating unit 10 as seen from above, omitting a part of the top plate 3 shown in the induction heating cooker 1 of FIG. FIG. 3 is a vertical cross-sectional view of the IH heating unit 10 as viewed from line III-III in FIG. As illustrated, the IH heating unit 10 according to the first embodiment includes an inner heating coil 20a and an outer heating coil 30 having different radii arranged substantially concentrically. Moreover, although it is arbitrary, the inner side heating coil 20 has the inner coil 20a and the outer coil 20b which are similarly arrange | positioned substantially concentrically and which has a different radius, and the inner coil 20a and the outer coil 20b are electrically connected in series. The IH heating unit 10 may be composed of an inner coil 20a, an outer coil 20b, and an outer heating coil 30 (triple coil structure).

  Further, as shown in FIG. 3, the IH heating unit 10 according to the first embodiment is disposed adjacent to the inner heating coil 20 (between the inner coil 20 a and the outer coil 20 b) below the top plate 3. An inner temperature sensor (temperature detection means) 21 and an outer temperature sensor 31 disposed adjacent to the outer heating coil 30 (between the outer coil 20b and the outer heating coil 30) are provided. The inner temperature sensor 21 may be disposed inside the inner coil 20 a and the outer temperature sensor 31 may be disposed outside the outer heating coil 30. These temperature sensors 21 and 31 may be any sensors that detect the surface temperature of the object to be heated (pan bottom) P. For example, a thermocouple, thermistor, or the like provided on the lower surface of the top plate 3. It may be an electrical temperature sensor such as a platinum resistance wire, or an optical temperature sensor such as an infrared CCD.

  FIG. 4 is a circuit block diagram schematically showing an electric circuit unit 40 for driving and controlling the IH heating unit 10 according to the first embodiment. The electric circuit unit 40 according to the first embodiment includes an inner drive circuit that supplies a high-frequency current independently to the inner heating coil 20 and the outer heating coil 30 that are illustrated as an equivalent circuit of the inductance L and the load resistance R in FIG. 50 and the outer drive circuit 60 (first and second drive circuits), a common control circuit 70 for individually controlling these drive circuits 50 and 60, and the inner temperature sensor 21 connected to the control circuit 70 And an outside temperature sensor 31 and an operation display unit 6 similarly connected to the control circuit 70.

More specifically, the drive circuits 50 and 60 are rectifier circuits (diode bridges 51 and 61, choke coils 52 and 62, smoothing capacitors 53 and 63) for rectifying an alternating current from the commercial power supply AC into a direct current, respectively. And resonant capacitors 54 and 64 connected in parallel to the heating coils 20 and 30, an inner driving voltage detection circuit 55 for detecting the driving voltage V applied to both ends of the heating coils 20 and 30, and an outer driving voltage detection. The circuit 65 includes an inner drive current detection circuit 56 and an outer drive current detection circuit 66 that measure the drive current I flowing through the heating coils 20 and 30. Furthermore, each drive circuit 50, 60 has an inner load detection circuit 57 and an outer load detection circuit 67 that can detect the placement state and constituent materials of the pan P based on the respective drive voltage V and drive current I.
The drive circuits 50 and 60 have inverter circuits composed of switching elements 58 and 68 such as IGBTs (Insulated Gate Bipolar Transistors) and FWDs (Free Wheeling Diodes) 59 and 69 connected in antiparallel. The high frequency current is supplied to the heating coils 20 and 30 in response to the gate signal.

ここでＶ_１，Ｉ_１は駆動電圧Ｖおよび駆動電流Ｉの１次成分を示し、Ｖ_１Re，Ｉ_１ReはＶ_１，Ｉ_１の実部、Ｖ_１Im，Ｉ_１ImはＶ_１，Ｉ_１の虚部、そしてｊは虚数単位を示す。 Although not shown in detail, each of the load detection circuits 57 and 67 is capable of extracting a high-frequency modulated drive voltage V and drive current I as a combined waveform including a high-order frequency component that is an integral multiple of the drive frequency. You may have an extraction means. FIG. 5 is a waveform diagram of the drive voltage and the drive current detected by the drive voltage detection circuits 55 and 65 and the drive current detection circuits 56 and 66. That is, the primary component extraction means uses the drive voltage V and the drive current I detected by the drive voltage detection circuits 55 and 65 and the drive current detection circuits 56 and 66 using, for example, a sampling frequency that is an integral multiple of the drive frequency. By performing a discrete Fourier transform, only a primary component (that is, a component having the same frequency as the drive frequency) is extracted from a signal having a plurality of higher-order frequency components of the drive voltage V and the drive current I, and is generally commercially available. It can be realized using the software.
At this time, the primary component extraction unit can perform complex display as the primary components of the drive voltage V and the drive current I as in the following equation.
[Equation 1]

Here, V ₁ and I ₁ indicate primary components of the driving voltage V and the driving current I, V _1Re and I _1Re are real parts of V ₁ and I ₁ , and V _1Im and I _1Im are imaginary _values of V ₁ and I ₁ . Part and j are imaginary units.

Impedance Z, and the drive voltage _{V 1} and the drive current _{I 1} phase (the driving voltages _{V 1} to the drive current _{I 1} phase or impedance Z phase) theta of the heating coils 20 and 30 is expressed by the following equation.
[Equation 2]

ここでωは１次成分の周波数ｆ（定義より駆動周波数と同一、ω＝２πｆで表される）であり、Ｃは共振コンデンサ５４，６４の静電容量であって、ともに既知である。したがって各負荷検出回路５７，６７は、［数３］から共振周波数Ｆｒと負荷抵抗Ｒを求めることができる。 On the other hand, in the drive circuits 50 and 60 including the heating coils 20 and 30, the load resistance R, impedance Z, inductance L and resonance frequency Fr of the heating coils 20 and 30 are expressed by the following equations.
[Equation 3]

Here, ω is the frequency f of the primary component (same as the drive frequency by definition, expressed by ω = 2πf), and C is the capacitance of the resonant capacitors 54 and 64, both of which are known. Therefore, each of the load detection circuits 57 and 67 can obtain the resonance frequency Fr and the load resistance R from [Equation 3].

  Generally, the obtained load resistance R is such that the pot P is placed at an appropriate position with respect to the heating coils 20 and 30 (placed state), that is, the wider area of the pot P is the heating coil 20. , 30 and the obtained resonance frequency Fr becomes larger than the case where the pan P is made of a nonmagnetic metal material such as aluminum or a nonmagnetic stainless material. It is known that the magnetic metal material is larger. More specifically, when the resonance frequency Fr and the load resistance R are detected by changing the area where the pan P made of various constituent materials is superimposed above the heating coils 20 and 30, the graph as shown in FIG. was gotten. Here, the region below the broken line in FIG. 6 is set as a drive inhibition region, and when the load detection circuits 57 and 67 detect the resonance frequency Fr and the load resistance R in the drive inhibition region, they are designated as control circuits. 70, the control circuit 70 preferably controls the drive circuits 50 and 60 so as not to supply high-frequency current to the heating coils 20 and 30. When the pan P is made of aluminum or when the pan P is not sufficiently placed above the heating coils 20 and 30, the electric circuit unit 40 configured in this way is further a spoon other than the pan P. When small items such as ladle and ladle are placed unintentionally, power supply to each heating coil 20 and 30 is stopped, and unnecessary power consumption and leakage magnetic flux are suppressed, and safe induction heating cooking is performed. Can be realized.

  In this way, the resonance frequency Fr and the load resistance R of the pan P are detected by the load detection circuits 57 and 67, an appropriate control method is determined by the control circuit 70, and the resonance frequency Fr and the load resistance R to be driven are determined. Control (including stopping power supply to each of the heating coils 20 and 30) is referred to as “load detection” or “pan detection” in the present specification.

  That is, the control circuit 70 determines the material and shape (large pan or small pan) of the pan P by performing load detection, and if it determines that the pan P is sufficiently placed, A signal (gate signal) for switching control 60 is output, and high frequency current (high frequency power) is supplied to each of the heating coils 20 and 30. And each heating coil 20 and 30 generates the alternating current magnetic flux according to the supplied high frequency electric power, and this generates the induced current (eddy current) in the pan P by interlinking with the bottom plate of the pan P, and the Joule The pan P is heated by heat.

  Returning to FIG. 4, the control circuit 70 according to the first embodiment controls the inner drive circuit 50 and the outer drive circuit 60 to supply a high-frequency current independently to the inner heating coil 20 and the outer heating coil 30. be able to. FIG. 7 is a timing chart showing the control method according to the first embodiment. The drive power (W) output from the inner drive circuit 50 and the outer drive circuit 60 and the time of the surface temperature (° C.) of the pan P It shows the transition.

In the control method shown in the timing chart of FIG. 7, the control circuit 70 roughly performs determination heating and drive heating as described in detail below. First, when the user drives the IH heating unit 10 using the operation display unit 6, the above-described load detection is performed and determination heating is performed.
In the determination heating, the control circuit 70 controls the inner drive circuit 50 so as to supply a predetermined determination pulse (determination power amount) to the inner heating coil 20 (FIG. 7A), and at the same time, uses the inner temperature sensor 21. The time change rate (dT ₁ / dt) of the temperature of the pan P measured in this way is calculated (solid line in FIG. 7C). The determination power amount supplied to the inner heating coil 20 may be, for example, power of several tens of watts applied for several seconds to several tens of seconds, and the magnitude of the determination power amount does not limit the present invention.
That is, when the determination pulse is supplied, the inner portion of the pan P is induction-heated by the inner heating coil 20 and the temperature rises, but the rate of increase (dT ₁ / dt) depends on the material constituting the inner portion of the pan P, It is influenced by the structure, and represents the easiness of heating to the inner part of the pan P (also referred to as “specific heating characteristics” in the present specification).

Next, a predetermined cooling period (for example, several seconds to several tens of seconds) has elapsed, and the detected temperatures of the inner temperature sensor 21 and the outer temperature sensor 31 are preferably substantially the same (the inner portion and the outer portion of the pan P). After reaching the thermal equilibrium state, the control circuit 70 controls the outer drive circuit 60 so as to supply a predetermined determination pulse (determination power amount) to the outer heating coil 30 (FIG. 7B) and at the same time, A time change rate (dT ₂ / dt) of the temperature of the pan P measured using the temperature sensor 31 is calculated (broken line in FIG. 7C). Although the determination electric energy supplied to the outer side heating coil 30 and the inner side heating coil 20 may differ, it is preferable that it is the same. In this way, the control circuit 70 calculates the rate of time change (dT ₂ / dt) of the temperature of the outer portion of the pan P when it is induction-heated by the outer heating coil 30 to which the determination electric energy is supplied. It is calculated as the easiness to heat (specific heating characteristics).

When the determination electric energy supplied to the inner heating coil 20 and the outer heating coil 30 is the same, the time change rates (dT ₁ / dt) and (dT ₂ / dt) calculated by the control circuit 70 are the inner parts of the pan P. It can be easily compared with the ease of heating the outer portion (specific heating characteristics). Therefore, the control circuit 70 according to the present invention controls the inner drive circuit 50 and the outer drive circuit 60 so as to supply a larger amount of power to a portion that is difficult to heat (a portion with a small time change rate) in the drive heating after the determination heating. It is something to try. For example, in the determination heating, the time change rate (dT ₂ / dt) of the temperature of the outer portion of the pan P is half (1/2 times) the time change rate (dT ₁ / dt) of the temperature of the inner portion of the pan P. ), It is judged that the outer part of the pan P is less likely to be heated twice as much as the inner part in the drive heating, and the entire amount of the pot P is made uniform by supplying twice the amount of power. Heat. That is, in the control circuit 70 according to the first embodiment, the ratio (Q ₁ / Q ₂ ) of the drive power amounts (Q ₁ , Q ₂ ) supplied to the heating coils 20, 30 is the temperature of the inner part of the pan P. By controlling each drive circuit 50, 60 so as to be the reciprocal of the ratio of the time change rate (dT ₁ / dt) of time and the time change rate (dT ₂ / dt) of the temperature of the outer portion of the pan P, Uniform heating of the entire P can be realized.
[Equation 4]
_{Q 1 / Q 2 = (dT} 2 / dt) / (dT 1 / dt)

More specifically, as shown in FIGS. 7A and 7B, the control circuit 70 drives each drive with the electric power (W ₀ ) supplied to the inner heating coil 20 and the outer heating coil 30 being constant. Each drive circuit 50, so that the ratio of time (t ₁ , t ₂ ) is the reciprocal of the ratio of the time change rate (dT ₁ / dt, dT ₂ / dt) of the inner and outer portions of the pan P. 60 may be controlled.
[Equation 5]
t ₁ / t ₂ = (dT ₂ / dt) / (dT ₁ / dt)
(Q ₁ = W ₀ × t ₁ , Q ₂ = W ₀ × t ₂ )

The control circuit 70 can supply high-frequency currents having different driving frequencies to the inner heating coil 20 and the outer heating coil 30, but these heating coils 20 and 30 are arranged close to each other. When a high-frequency current having a different frequency is supplied, a beat sound corresponding to the difference frequency is generated, and particularly when these difference frequencies are in an audible range, the user may be significantly uncomfortable. Therefore, it is preferable that the control circuit 70 supplies a high frequency current having the same drive frequency to each of the heating coils 20 and 30.
When the control circuit 70 determines a predetermined heating cycle (τ) and is set equal to the sum of the drive times (t ₁ , t ₂ ) (τ = t ₁ + t ₂ ), each drive time (t ₁ , t ₂ ) can be easily obtained by the following equation.
[Equation 6]
t ₁ = τ × (dT ₂ / dt) / {(dT ₁ / dt) + (dT ₂ / dt)}
t ₂ = τ × (dT ₁ / dt) / {(dT ₁ / dt) + (dT ₂ / dt)}

Alternatively, as shown in FIGS. 8A to 8C, the control circuit 70 similarly supplies a high-frequency current having the same drive frequency to the inner heating coil 20 and the outer heating coil 30. The driving time (t ₀ ) is constant, and the ratio of the power (W ₁ , W ₂ ) supplied to each heating coil 20, 30 is the rate of time change (dT _{1) in} the temperature of the inner and outer portions of the pan P. The drive circuits 50 and 60 may be controlled so as to be a reciprocal of the ratio of / dt, dT ₂ / dt).
[Equation 7]
W ₁ / W ₂ = (dT ₂ / dt) / (dT ₁ / dt)
(Q ₁ = W ₁ × t ₀ , Q ₂ = W ₂ × t ₀ )

Incidentally, according to the control method shown in FIG. 7, in order to uniformly heat the pan P, the power supplied to the respective heating coils 20 and 30 (W ₀₎ is constant, the drive time (t _1, t ₂ 8), and according to the control method shown in FIG. 8, the driving time (t ₀ ) supplied to each heating coil 20, 30 is constant, and the power (W) supplied to each heating coil (W ₁ , W ₂ ). However, the present invention is not limited to these, and each heating coil is controlled by controlling both the electric power (W ₁ , W ₂ ) and each driving time (t ₁ , t ₂ ) supplied to each heating coil 20, 30. The ratio (Q ₁ / Q ₂ ) of the drive electric energy (Q ₁ , Q ₂ ) supplied to 20, 30 is the time change rate (dT ₁ / dt, dT ₂ ) of the inner part and the outer part of the pan P. The drive circuits 50 and 60 may be controlled so as to be a reciprocal of the ratio / dt).

Modification 1
FIG. 9 is a plan view showing the IH heating unit 10 according to the first modification of the first embodiment. The IH heating unit 10 according to the first embodiment has the two temperature sensors 21 and 31 disposed adjacent to the inner heating coil 20 and the outer heating coil 30 below the top plate 3. As shown in FIG. 9, the IH heating unit 10 according to the modification 1 may include a single temperature sensor 31 disposed between the inner heating coil 20 and the outer heating coil 30, The heating coil 20 may be integrated without being separated into the inner coil 20a and the outer coil 20b.

At this time, the temperature of the inner part and the outer part of the pan P is measured by a single temperature sensor 31, but the rate of change in temperature of the inner part and the outer part with time (dT ₁ / dt, dT ₂ / In order to measure dt) more accurately, it is preferable to perform the measurement after the influence of heating by the inner heating coil 20 becomes sufficiently small before measuring the temperature of the outer portion of the pan P. Therefore, when the temperature of the inner part and the outer part of the pan P is measured by the single temperature sensor 31, the control circuit 70 controls the inner driving circuit 50 so as to supply a predetermined determination pulse to the inner heating coil 20. Thereafter, after a sufficiently long cooling period (for example, several seconds to several tens of seconds) has elapsed, that is, after the inner portion and the outer portion of the pan P have sufficiently reached a thermal equilibrium state, a predetermined determination pulse is applied to the outer heating coil 30. It is preferable to control the outer drive circuit 60 to supply.

Embodiment 2. FIG.
Embodiment 2 of the induction heating cooker according to the present invention will be described in detail below with reference to FIGS. The IH heating unit 10 of the second embodiment is generally the same as the IH heating unit 10 of the first embodiment except that four peripheral heating coils 30a to 30d are arranged adjacent to the periphery of the central heating coil 20. Since it has a configuration, the description of overlapping points is omitted.

  Although not shown in detail, the electric circuit unit 40 according to the second embodiment includes a central driving circuit 50 and peripheral driving circuits 60a to 60a that supply a high-frequency current independently to the central heating coil 20 and the four peripheral heating coils 30a to 30d. 60d, a common control circuit 70 for individually controlling the drive circuits 50, 60a to 60d, the central temperature sensor 21 and the four ambient temperature sensors 31a to 31d connected to the control circuit 70, and the like And an operation display unit 6 connected to the control circuit 70. In the IH heating unit 10 shown in FIG. 10, the central temperature sensor 21 is disposed inside the central heating coil 20, and the peripheral temperature sensors 31 a to 31 d are similarly disposed inside the peripheral heating coils 30 a to 30 d.

  Each of the peripheral drive circuits 60a to 60d has a circuit configuration equivalent to that of the inner drive circuit 50 shown in FIG. 4, and the load detection circuits 57 and 67a to 67d included therein also have the same function as described above. That is, although not shown in detail, the central load detection circuit 57 includes a central drive current detection unit that detects a drive current (central drive current) flowing through the central heating coil 20 and a drive voltage (a voltage applied to both ends of the central heating coil 20). Central drive voltage detection means for detecting a central drive voltage). Similarly, the peripheral load detection circuits 67a to 67d are applied to peripheral drive current detection means for detecting drive current (peripheral drive current) flowing through the peripheral heating coils 30a to 30d and to both ends of the peripheral heating coils 30a to 30d. Peripheral drive voltage detection means for detecting the drive voltage (peripheral drive voltage).

  Thus, the control circuit 70 obtains the resonance frequency Fr and the load resistance R of the pan P placed above the central heating coil 20 based on the central drive current and the central drive voltage, and uses them for the heating determination map of FIG. Then, it is determined whether or not a high frequency current should be supplied to the central heating coil 20. Similarly, the control circuit 70 obtains the resonance frequency Fr and the load resistance R of the pan P placed above the peripheral heating coils 30a to 30d based on the peripheral drive current and the peripheral drive voltage, and displays the heating determination map. It is determined whether or not high frequency current should be supplied to each of the peripheral heating coils 30a to 30d with reference.

Next, operation | movement of the IH heating part 10 of Embodiment 2 is demonstrated in detail below.
When the user drives the IH heating unit 10 using the operation display unit 6, the control circuit 70 performs the above-described load detection and starts determination heating, as in the first embodiment. Specifically, the load detection circuits 57 and 67 detect the resonance frequency Fr and load resistance R of the pan P, the control circuit 70 determines an appropriate control method, and the resonance frequency Fr and load resistance R to be driven. To control.

FIG. 11 is a timing chart showing the control method according to the second embodiment, and the determination power and the time transition of the driving power in the determination heating and the driving heating output from the central drive circuit 50 and the peripheral drive circuits 60a to 60d. Is shown. The control circuit 70 supplies the central driving circuit 50 and the peripheral driving circuits so as to sequentially supply a predetermined determination pulse (determination power amount) to the central heating coil 20 and the peripheral heating coils 30a to 30d after a predetermined cooling period. at the same time to control the 60 a to 60 d (FIG. 11 (a) ~ (e) ), the time rate of change of the measured temperature of the pan P using the temperature sensor _{21,31a~31d (dT 1 / dt, dT} 2 / dt, dT ₃ / dt, dT ₄ / dt, dT ₅ / dt) (all not shown). The determination power amount supplied to each of the heating coils 20, 30a to 30d may be, for example, a power of the order of several tens of W applied for several seconds to several tens of seconds, and the magnitude of the determination power amount limits the present invention. It is not a thing.

When the determination pulse is supplied to the central heating coil 20 and each of the peripheral heating coils 30a to 30d, the temperature of the central portion and the peripheral portion of the pan P rises correspondingly. It is influenced by the material and structure constituting the central portion and the peripheral portion, and expresses the ease of heating (specific heating characteristics) inherent to the central portion and the peripheral portion of the pan P. The control circuit 70 according to the second embodiment easily heats the time change rate (dT _i / dt, i = 1 to 5) of the temperature depending on the portion (region) of the pan P in the driving heating after the determination heating. It is considered as an index representing the thickness, and by supplying a larger amount of power to a portion that is difficult to heat (a portion with a small time change rate), the pan P is to be heated uniformly regardless of the portion (region). That is, the control circuit 70 controls the central drive circuit 50 and the peripheral drive circuits 60a to 60d so as to satisfy the following expression in the drive heating after the determination heating.
[Equation 8]
_{Q 1 / Q 2 = (dT} 2 / dt) / (dT 1 / dt)
_{Q 1 / Q 3 = (dT} 3 / dt) / (dT 1 / dt)
_{Q 1 / Q 4 = (dT} 4 / dt) / (dT 1 / dt)
_{Q 1 / Q 5 = (dT} 5 / dt) / (dT 1 / dt)

At this time, the high-frequency current supplied to the central heating coil 20 and the peripheral heating coils 30a to 30d preferably has the same drive frequency in order to suppress generation of beat sounds having frequencies corresponding to these differential frequencies. . Then, as shown in FIGS. 11A to 11E, the control circuit 70 sets the electric power (W ₀ ) supplied to the central heating coil 20 and the peripheral heating coils 30a to 30d to be constant, Each of the drive circuits 50, 60a to 60 so that the ratio of t _{1 to} t ₅ ) is a reciprocal of the ratio of the time change rate (dT ₁ / dt to dT ₅ / dt) of the temperature at the central portion and the peripheral portion of the pan P. 60d may be controlled.
[Equation 9]
t ₁ / t ₂ = (dT ₂ / dt) / (dT ₁ / dt)
t ₁ / t ₃ = (dT ₃ / dt) / (dT ₁ / dt)
t ₁ / t ₄ = (dT ₄ / dt) / (dT ₁ / dt)
t ₁ / t ₅ = (dT ₅ / dt) / (dT ₁ / dt)

Alternatively, although not shown in detail, the control circuit 70 makes the driving time (t ₀ ) for supplying a high-frequency current having the same driving frequency to the central heating coil 20 and the peripheral heating coils 30a to 30d constant, The ratio of the electric power (W _{1 to} W ₅ ) supplied to the central heating coil 20 and each of the peripheral heating coils 30a to 30d is the time change rate of the temperature of each part of the pan P (dT ₁ / dt to dT ₅ / dt). The drive circuits 50, 60a to 60d may be controlled so as to be a reciprocal of the ratio.
[Equation 10]
W ₁ / W ₂ = (dT ₂ / dt) / (dT ₁ / dt)
W ₁ / W ₃ = (dT ₃ / dt) / (dT ₁ / dt)
_{W 1 / W 4 = (dT} 4 / dt) / (dT 1 / dt)
_{W 1 / W 5 = (dT} 5 / dt) / (dT 1 / dt)
As described above, the control circuit 70 controls the central driving circuit 50 and the peripheral driving circuits 60a to 60d, so that each portion of the pan P corresponding to or adjacent to the central heating coil 20 and the peripheral heating coils 30a to 30d is controlled. Regardless of the configuration including the material and shape of the pan P, and regardless of the specific heating characteristics according to the region of the pan bottom, it can be heated uniformly.

In the second embodiment, by arranging the plurality of peripheral heating coils 30a to 30d around the central heating coil 20, the following advantages can be obtained.
That is, in Embodiment 1, when the pan P is placed out of the center position (FIG. 12 (a)) or when the elliptical pan P is placed (FIG. 12 (b)), the outer drive is performed. When the load detection circuit 67 of the circuit 60 performs load detection and determines that the pan P is not sufficiently placed above the outer heating coil 30 and the outer drive circuit 60 is not driven, the control according to the present invention is originally performed. The method cannot be applied.
However, in the second embodiment, when the pan P is similarly placed out of the center position (FIG. 12 (a)), the load detection circuits 57, 67a to 67d of the drive circuits 50 and 60a to 60d are loaded. Even if it is determined that the pan P is not sufficiently placed above the peripheral heating coils 30a and 30b, the control method according to the present invention is applied to the central heating coil 20 and the peripheral heating coils 30c and 30d. Can be applied to heat the pan P uniformly.
Moreover, in Embodiment 2, when the ellipse pan P is mounted (FIG.12 (b)), each load detection circuit 57,67a-67d performs load detection, and the pan P is the periphery heating coils 30b and 30d. Even when it is determined that the pan is not sufficiently placed above, the control method according to the present invention is applied to the central heating coil 20 and the peripheral heating coils 30a, 30c to uniformly heat the pan P. Can do.

Modification 2
As described above, according to the IH heating unit 10 according to the second embodiment, the central temperature sensor 21 is disposed inside the central heating coil 20, and the peripheral temperature sensors 31a to 31d are similarly connected to the peripheral heating coils 30a to 30d. It is arranged inside. The IH heating unit 10 according to the modified example 2 omits the central temperature sensor 21 disposed inside the central heating coil 20, and as shown in FIG. 14, the adjacent peripheral heating coils 30 a to 30 d and the central heating coil 20 are adjacent to each other. Ambient temperature sensors 31a to 31d disposed between the two. Each of the ambient temperature sensors 31 a to 31 d is preferably arranged point-symmetrically with respect to the center of the central heating coil 20. According to the second modification, the temperature of the central heating coil 20 is not directly measured, but is calculated by the control circuit 70 as an average value of the temperatures measured by the respective ambient temperature sensors 31a to 31d. Thus, since one temperature sensor can be omitted, the manufacturing cost of the IH heating unit 10 can be reduced.

Similarly to the second embodiment, when the pan P is placed so as to deviate from the center position in the lower left direction in the figure (FIG. 15 (a)), the load detection circuits 57, 67a of the drive circuits 50, 60a to 60d. When -67d performs load detection and it is determined that the pan P is not sufficiently placed above the peripheral heating coils 30a, 30b, the central heating coil 20 and the peripheral heating coil 30c using the peripheral temperature sensors 31b-31d , 30d can be heated uniformly by applying the control method according to the present invention to the pot portion corresponding to 30d.
Moreover, when pan P is deviated from the center position in the left direction in the figure (FIG. 15B), it is determined that pan P is not sufficiently placed above peripheral heating coils 30a to 30c. When it does, the control circuit 70 applies the control method which concerns on this invention about the pan part corresponding to the central heating coil 20 and the peripheral heating coil 30d using the ambient temperature sensors 31c and 31d, and heats the pan P uniformly. be able to.

Modification 3
According to the modified example 2, the central temperature sensor 21 disposed inside the central heating coil 20 is omitted, and the temperature of the central heating coil 20 is controlled as an average value of the temperatures measured by the respective ambient temperature sensors 31a to 31d. Although calculated by the circuit 70, the IH heating unit 10 according to the third modification illustrated in FIG. 16 further omits the ambient temperature sensors 31b and 31d illustrated in FIG. That is, the temperature of the peripheral heating coils 30a and 30b is measured by the peripheral temperature sensor 31a, the temperature of the peripheral heating coils 30c and 30d is measured by the peripheral temperature sensor 31c, and the temperature of the central heating coil 20 is measured by the peripheral temperature sensors 31a and 31c. The average value of the calculated temperatures is calculated by the control circuit 70. In this way, since two more temperature sensors can be omitted, the manufacturing cost can be reduced.

Modification 4
Furthermore, the electric circuit unit 40 according to the second embodiment includes a central driving circuit 50 and peripheral driving circuits 60a to 60d that supply the high-frequency current independently to the central heating coil 20 and the four peripheral heating coils 30a to 30d. However, the electric circuit unit 40 according to the modified example 4 includes the peripheral heating coils 30a and 30c connected in series or in parallel, and the peripheral heating coils 30b and 30d connected in series or in parallel. It is also possible to have two peripheral drive circuits 50a and 50c that supply a high-frequency current independently. FIG. 17 is a timing chart showing a control method according to the fourth modification, and shows time transitions of judgment power and driving power in judgment heating and driving heating output to the central heating coil 20 and the peripheral heating coils 30a to 30d. Is.

In the determination heating, the control circuit 70 sequentially supplies a predetermined determination pulse (determination electric energy) to the central heating coil 20, the peripheral heating coils 30a and 30c, and the peripheral heating coils 30b and 30d. peripheral driver circuit 60a, and at the same time to control 60c, the time rate of change of the temperature of the pan P which is measured using the temperature sensor 21,31a~31d a _{(dT 1 / dt~dT 5 / dt} ) is calculated (both Not shown).
Then, in the driving heating after the determination heating, the control circuit 70 is a portion that is difficult to heat as an index indicating the ease of heating the time change rate of the temperature depending on the portion (region) of the pan P as in the second embodiment. By supplying a larger amount of power as the (time change rate is smaller), the pan P can be heated uniformly regardless of the portion (region).

1: induction heating cooker 2: casing, 3: top plate, 4: central heating unit, 5: grill for cooking, 6: operation display unit, 7: intake window, 8: exhaust window, 10, 11: IH heating , 20: inner heating coil (central heating coil), 30: outer heating coil (peripheral heating coil), 21, 31: temperature sensor (temperature detection means), 40: electric circuit unit, 50, 60: drive circuit, 51 , 61: Diode bridge, 52, 62: Choke coil, 53, 63: Smoothing capacitor, 54, 64: Resonance capacitor, 55, 65: Drive voltage detection circuit, 56, 66: Drive current detection circuit, 57, 67: Load Detection circuit, 58, 68: switching element, 59, 69: FWD, 70: control circuit, P: heated object (pan).

Claims (8)

At least one central heating coil for heating a single object to be heated and a plurality of peripheral heating coils arranged around the central heating coil;
A central drive circuit and a plurality of peripheral drive circuits for supplying a high-frequency current independently to the central heating coil and each of the peripheral heating coils;
A central driving current detecting means for detecting a central driving current flowing in the central heating coil;
A plurality of peripheral drive current detection means for detecting peripheral drive current flowing in each peripheral heating coil;
A central driving voltage detecting means for detecting a central driving voltage applied to both ends of the central heating coil;
A plurality of peripheral drive voltage detecting means for detecting peripheral drive voltages applied to both ends of each peripheral heating coil;
A control circuit for independently controlling the central drive circuit and the peripheral drive circuits;
And at least one temperature detecting means for detecting the temperature of the heated object,
When the control circuit controls the central drive circuit to supply a predetermined determination power amount to the central heating coil, the central time change of the temperature (T) of the heated object detected by the temperature detection means The heated object detected by the temperature detecting means when calculating the rate (dT ₁ / dt) and controlling each peripheral drive circuit to supply a predetermined determination power amount to each peripheral heating coil A plurality of ambient time change rates (dT ₂ / dt,..., DT _i / dt, i is a natural number of 3 or more),
The control circuit includes a central driving power amount (Q ₁ ) supplied to the central heating coil, and a plurality of peripheral driving power amounts (Q ₂ ,..., Q _i ) supplied to the peripheral heating coils. Ratio (Q ₁ / Q ₂ ,..., Q ₁ / Q _i ) is the central time change rate (dT ₁ / dt) and the respective peripheral time change rates (dT ₂ / dt,..., DT). said central driving circuit and the respective peripheral driving circuit is controlled so that the reciprocal of the ratio of _{i /} dt),
The control circuit determines whether or not a high frequency current should be supplied to the central heating coil based on the central drive current and the central drive voltage, and based on the peripheral drive current and the peripheral drive voltage, Whether to be supplied to each of the peripheral heating coils,
Based on the temperature (T) of the heated object detected by the ambient temperature sensor that is not adjacent to the ambient heating coil that is determined not to supply the high frequency current, the central time rate of change (dT ₁ / dt) and An induction heating cooker that calculates a plurality of peripheral time change rates (dT ₂ / dt,..., DT _i / dt, i is a natural number of 3 or more) . The control circuit controls the central driving circuit and the peripheral driving circuits to independently supply a high-frequency current of the same frequency to each of the central heating coil and the peripheral heating coils ;
Wherein the control circuit comprises a central heating coil and the drive power of the central heating coil and the respective peripheral heating coil is supplied to each of the peripheral heating coil (W ₀₎ is constant, the central heating coil and the respective peripheral The ratio of the drive time (t ₁ , t ₂ ,..., T _i ) during which the high-frequency current is supplied to the heating coil is a central time change rate (dT ₁ / dt) and a plurality of peripheral time change rates (dT ₂ / dt The induction heating cooker according to claim 1 , wherein the central drive circuit and the plurality of peripheral drive circuits are controlled so as to be a reciprocal of a ratio of (dT _i / dt) . The control circuit controls the central driving circuit and the peripheral driving circuits to independently supply a high-frequency current of the same frequency to each of the central heating coil and the peripheral heating coils ;
Wherein the control circuit comprises and central heating coil and the driving time each high-frequency current of each peripheral heating coil is supplied with (t ₀₎ is constant, the driving power supplied to the central heating coil and the respective peripheral heating coil The ratio of (W ₁ , W ₂ ,..., W _i ) is the central time change rate (dT ₁ / dt) and a plurality of peripheral time change rates (dT ₂ / dt,..., DT _i / dt) . The induction heating cooker according to claim 1, wherein the central driving circuit and the plurality of peripheral driving circuits are controlled so as to have an inverse of the ratio. The control circuit controls the central driving circuit and the peripheral driving circuits to independently supply a high-frequency current of the same frequency to each of the central heating coil and the peripheral heating coils ;
Wherein the control circuit, the central heating coil and the driving power supplied to each of the peripheral heating coil _{(W 1, W 2, ···} , W i), as well as the central heating coil and the respective peripheral heating coil _2. The induction heating cooker according to claim 1, wherein both the driving time (t ₁ , t ₂ ,..., T _i ) during which the high-frequency current is supplied are controlled. The temperature detection means includes a central temperature sensor and a plurality of ambient temperature sensors arranged adjacent to each of the central heating coil and each of the peripheral heating coils ,
When the control circuit controls the central drive circuit so as to supply a predetermined determination electric energy to the central heating coil , the central time change rate of the temperature (T ₁ ) of the heated object detected by the central temperature sensor While calculating (dT ₁ / dt) and controlling each peripheral drive circuit so as to supply a predetermined determination power amount to each peripheral heating coil, the temperature of the object to be heated detected by each peripheral temperature sensor _{(T 2, T 3, ···} , T i) near the time rate of change _{(dT 2 / dt, ···,} dT i / dt) induction heating according to claim 1, characterized in that to calculate the Cooking device. It said temperature detecting means comprises a plurality of peripheral temperature sensors disposed adjacent to the respective peripheral heating coils,
Said control circuit, when said controlled said central driving circuit to supply a predetermined judgment amount of power to the central heating coil, the average value of the temperature of the heated object detected by the ambient temperature sensor (T ₁₎ The first time rate of change (dT ₁ / dt) is calculated and each peripheral drive circuit is controlled so as to supply a predetermined amount of electric power to each peripheral heating coil. the temperature of the object to be heated which is _{(T 2, ···, T i} ) near the time rate of change _{(dT 2 / dt, ···,} dT i / dt) in claim 1, characterized in that to calculate the The induction heating cooker described. It said temperature detecting means includes a central temperature sensor disposed adjacent to the central heating coil,
Said control circuit, when controlling the central driving circuit to supply a predetermined judgment amount of power to the central heating coil, the average value of the temperature of the object to be heated detected by the central temperature sensor (T ₁₎ The induction heating cooker according to claim 1, wherein a first time change rate (dT ₁ / dt) is calculated. A control method for an induction heating cooker having at least one central heating coil for heating a single object to be heated and a plurality of peripheral heating coils arranged therearound,
Measuring the temperature (T) of the object to be heated using a central temperature sensor disposed adjacent to the central heating coil and a plurality of ambient temperature sensors disposed adjacent to each peripheral heating coil;
Detecting a central drive current flowing through the central heating coil;
Detecting a peripheral drive current flowing through each of the peripheral heating coils;
Detecting a central drive voltage applied across the central heating coil;
Detecting a peripheral driving voltage applied to both ends of each peripheral heating coil;
Supplying a predetermined determination electric energy to the central heating coil, measuring a temperature (T) of the heated object, and calculating a central time change rate (dT ₁ / dt);
A predetermined determination electric energy is supplied to each of the peripheral heating coils, the temperature (T) of the heated object is measured, and a plurality of peripheral time change rates (dT ₂ / dt,..., DT _i / dt, i is a natural number of 3 or more),
A ratio (Q ₁ ) between a central driving power amount (Q ₁ ) supplied to the central heating coil and a plurality of central driving power amounts (Q ₂ ,..., Q _i ) supplied to the peripheral heating coils. / Q ₂ ,..., Q ₁ / Q _i ) is a ratio of the central time change rate (dT ₁ / dt) and each peripheral time change rate (dT ₂ / dt,..., DT _i / dt). Controlling the central drive energy and each central drive energy to be the inverse of the ratio ;
Based on the central driving current and the central driving voltage, it is determined whether a high frequency current should be supplied to the central heating coil, and a high frequency current is supplied to each heating coil based on the peripheral driving current and the peripheral driving voltage. Determining whether or not to do so;
Based on the temperature (T) of the heated object detected by the ambient temperature sensor not adjacent to the ambient heating coil determined not to supply the high-frequency current, the central time change rate (dT ₁ / dt) and a plurality of And a step of calculating a peripheral time change rate (dT ₂ / dt,..., DT _i / dt, i is a natural number of 3 or more) .

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