CN104170524B

CN104170524B - Induction heating cooking instrument

Info

Publication number: CN104170524B
Application number: CN201380014442.5A
Authority: CN
Inventors: 吉野勇人; 高野浩志郎; 森井彰; 西健一郎; 田村宪一
Original assignee: Mitsubishi Electric Home Appliance Co Ltd; Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Home Appliance Co Ltd; Mitsubishi Electric Corp
Priority date: 2012-03-14
Filing date: 2013-03-13
Publication date: 2016-01-27
Anticipated expiration: 2033-03-13
Also published as: CN104170524A; JP2016181518A; JPWO2013137287A1; EP2827679A4; EP2827679B1; JP6141492B2; JP6238888B2; ES2573657T3; WO2013136577A1; WO2013137287A1; EP2827679A1

Abstract

According to the result of determination of load identifying unit, drive inverter circuit (23), under the state of driving frequency securing inverter circuit (23), obtain the variable quantity of per stipulated time of input current or coil current, according to the variable quantity of per stipulated time, the variations in temperature of detection heating object (5).

Description

Induction heating cooking instrument

Technical field

The present invention relates to induction heating cooking instrument.

Background technology

In induction heating cooking instrument in the past, there is the example by the input current of inverter, the temperature of controlled quentity controlled variable judgement heating object.

Such as, propose the control unit having to make the input current of inverter to become constant mode control inverter, within the stipulated time, there is the variations in temperature being judged as heating object when the change of the controlled quentity controlled variable of more than regulation to suppress greatly the induction heating cooking instrument (for example, referring to patent documentation 1) of the output of inverter.

In addition such as, propose the temperature-detecting device (for example, referring to patent documentation 2) of the induction heating cooking instrument possessing the temperature determination processing unit judging the temperature corresponding with the variable quantity of the input current that the input current change amount detection by the variable quantity only detecting input current detects.

Patent documentation 1: Japanese Unexamined Patent Publication 2008-181892 publication (the 3rd page ~ the 5th page, Fig. 1)

Patent documentation 2: Japanese Unexamined Patent Publication 5-62773 publication (the 2nd page ~ the 3rd page, Fig. 1)

Summary of the invention

In the induction heating cooking instrument that patent documentation 1 is recorded, in the mode making input electric power become constant, the driving frequency of control inverter, has judged the variations in temperature of heating object according to its controlled quentity controlled variable change (Δ f).But there is the material according to heating object, controlled quentity controlled variable change (Δ f) of driving frequency becomes small, and the problem that the variations in temperature that cannot detect heating object is such.

In the temperature-detecting device of the induction heating cooking instrument of patent documentation 2 record, there are the following problems: when the material of heating object has changed, and according to the driving frequency of inverter, likely input current becomes excessive, and inverter becomes high temperature and destroys.

The present invention completes, no matter what the material that its object is to obtain a kind of heating object be and can both detect the induction heating cooking instrument of the variations in temperature of heating object to solve problem as described above.In addition, obtain a kind ofly inhibit the induction heating cooking instrument that the reliability of the increase of input current is high.

Induction heating cooking instrument of the present invention, is characterized in that, possesses: heater coil, carries out induction heating to heating object; Drive circuit, to described heater coil supply high frequency electric power; Load identifying unit, carries out the load determination processing of described heater coil; And control part, control the driving of described drive circuit, control the High frequency power that described heater coil is supplied, described control part is according to the result of determination of described load identifying unit, described drive circuit is driven, under the state of driving frequency securing described drive circuit, obtain the variable quantity of per stipulated time of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit, according to the variable quantity of described per stipulated time, detect the variations in temperature of described heating object.

No matter what the material of the present invention's heating object is, the variations in temperature of heating object can both be detected.In addition, the increase of input current can be suppressed, can reliability be improved.

Accompanying drawing explanation

Fig. 1 is the exploded perspective view of the induction heating cooking instrument that execution mode 1 is shown.

Fig. 2 is the figure of the drive circuit of the induction heating cooking instrument that execution mode 1 is shown.

Fig. 3 is that the load of the heating object of the relation based on heating coil current and input current in the induction heating cooking instrument of execution mode 1 differentiates performance plot.

The correlation diagram of the relative driving frequency of input current when Fig. 4 is the variations in temperature of the heating object of the induction heating cooking instrument of execution mode 1.

Fig. 5 is the figure of the part shown in dotted line being exaggerated Fig. 4.

Fig. 6 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 1 is shown, temperature, input current and the relation of time.

Fig. 7 is the figure of the part shown in dotted line being exaggerated Fig. 4.

Fig. 8 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 1 is shown, temperature, input current and the relation of time.

Fig. 9 is the figure of other drive circuit of the induction heating cooking instrument that execution mode 1 is shown.

Figure 10 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 2 is shown, temperature, input current and the relation of time.

Figure 11 is the figure of a part for the drive circuit of the induction heating cooking instrument that execution mode 3 is shown.

Figure 12 is the figure of an example of the drive singal of the half-bridge circuit that execution mode 3 is shown.

Figure 13 is the figure of a part for the drive circuit of the induction heating cooking instrument that execution mode 4 is shown.

Figure 14 is the figure of an example of the drive singal of the full-bridge circuit that execution mode 4 is shown.

Symbol description

1: the first heating gate; 2: the second heating gates; 3: the three heating gates; 4: top board; 5: heating object; 11: the first heating units; 11a: heater coil; 12: the second heating units; 13: the three heating units; 21: AC power; 22: DC power supply circuit; 22a: diode bridge; 22b: reactor; 22c: smmothing capacitor; 23: inverter circuit; 23a, 23b:IGBT; 23c, 23d: diode; 24a, 24b: resonating capacitor; 25a: input electric cur-rent measure unit; 25b: coil current detecting unit; 30: temperature detecting unit; 40a ~ 40c: operating portion; 41a ~ 41c: display part; 42: reporting unit; 45: control part; 50: drive circuit; 100: induction heating cooking instrument; 11b: interior loop; 11c: exterior loop; 24c, 24d: resonating capacitor; 25c, 25d: coil current detecting unit; 231a, 231b, 232a, 232b, 233a, 233b:IGBT; 231c, 231d, 232c, 232d, 233c, 233d: diode.

Embodiment

Execution mode 1.

(structure)

As shown in Figure 1, on the top of induction heating cooking instrument 100, there is the top board 4 of the heating objects 5 such as mounting pot.In top board 4, as the heating gate for carrying out induction heating to heating object 5, possess the first heating gate 1, second heating gate 2, the 3rd heating gate 3, with each heating gate accordingly, possess the first heating unit 11, second heating unit 12, the 3rd heating unit 13, induction heating can be carried out for each heating gate mounting heating object 5.

In present embodiment 1, be provided with the first heating unit 11 and the second heating unit 12 at side, the front left-right situs of main body, be provided with the 3rd heating unit 13 in the inboard substantial middle of main body.

In addition, the configuration of each heating gate is not limited thereto.Such as, also can according to the transversely arranged configuration of substantially linear 3 heating gates.In addition, the center that also can be configured to the first heating unit 11 is different from the position of the depth direction at the center of the second heating unit 12.

The entirety of top board 4 by resistance to thermal reinforced glass, sintered glass ceramics etc. make infrared ray through material form, between the upper surface open periphery of induction heating cooking instrument 100 main body, be fixed to watertight state by rubber seal, encapsulant.In top board 4, with the Tong Guo Tu coating, printing etc. of expecting accordingly of the heated perimeter (heating gate) of the first heating unit 11, second heating unit 12 and the 3rd heating unit 13, define the pot position display of the circle of the rough mounting position representing pot.

In the side, front of top board 4, as the input unit for setting firepower when heating with the first heating unit 11, second heating unit 12 and the 3rd heating unit 13 pairs of heating objects 5, cooking menu (heat up water pattern, fried pattern etc.), be provided with operating portion 40a, operating portion 40b and operating portion 40c (being sometimes generically and collectively referred to as operating portion 40 below).In addition, near operating portion 40, as reporting unit 42, be provided with the operate condition of display induction heating cooking instrument 100, display part 41a, display part 41b and display part 41c from the input/content of operation etc. of operating portion 40.In addition, have and be provided with the situation of operating portion 40a ~ 40c and display part 41a ~ 41c, the situation etc. for heating gate setting operation portion 40 and display part 41 together for each heating gate, be not particularly limited.

In the below of top board 4 and the inside of main body, possess the first heating unit 11, second heating unit 12 and the 3rd heating unit 13, each heating unit is made up of heater coil (not shown).

In the inside of the main body of induction heating cooking instrument 100, be provided with the control part 45 to the drive circuit 50 of the heater coil supply high frequency electric power of the first heating unit 11, second heating unit 12 and the 3rd heating unit 13 and the action for the induction heating cooking instrument entirety that controls to comprise drive circuit 50.

In addition, the control part 45 in present embodiment is formed " control part " and " load identifying unit " in the present invention.

Heater coil has the flat shape of circular, by being made up of the conductor wire formed by the arbitrary metal (such as copper, aluminium etc.) of the tunicle that insulate at circumferencial direction winding, by utilizing drive circuit 50 to each heater coil supply high frequency electric power, carry out induction heating action.

Fig. 2 is the figure of the drive circuit of the induction heating cooking instrument that execution mode 1 is shown.In addition, drive circuit 50 is arranged for each heating unit, and its structure is identical.In fig. 2, illustrate only 1 drive circuit 50.

As shown in Figure 2, drive circuit 50 possesses DC power supply circuit 22, inverter circuit 23 and resonating capacitor 24a.

Input electric cur-rent measure unit 25a detects the electric current of the input from AC power (source power supply) 21 to DC power supply circuit 22, and the voltage signal suitable with input current value is outputted to control part 45.

DC power supply circuit 22 possesses diode bridge 22a, reactor 22b, smmothing capacitor 22c, and the alternating voltage inputted from AC power 21 is transformed to direct voltage, outputs to inverter circuit 23.

About inverter circuit 23, IGBT23a, 23b as switch element are the inverters of the so-called semi-bridge type be connected in series with the output of DC power supply circuit 22, and as fly-wheel diode, diode 23c, 23d are connected in parallel with IGBT23a, 23b respectively.The direct current power exported from DC power supply circuit 22 is transformed to the alternating electromotive force of the high frequency of about 20kHz ~ 50kHz by inverter circuit 23, is supplied to the resonant circuit be made up of heater coil 11a and resonating capacitor 24a.

By such formation, in heater coil 11a, flow through the high-frequency current of about tens A, by the high frequency magnetic flux produced by the high-frequency current flow through, induction heating is carried out to the heating object 5 loaded on the top board 4 just gone up of heater coil 11a.IGBT23a, 23b as switch element are made up of the semiconductor be such as made up of silicon system, but also can be the use of the wide bandgap such as carborundum or gallium nitride based material semiconductor structure.

Coil current detecting unit 25b is connected between heater coil 11a and resonating capacitor 24a.The voltage signal suitable with the peak value of heating coil current, as the peak value of the electric current flow through in heater coil 11a, is outputted to control part 45 by coil current detecting unit 25b test example.

Temperature detecting unit 30 is made up of such as thermistor, according to the heat transferring heat to top board 4 from heating object 5, and detecting temperature.In addition, be not limited to thermistor, also can use the arbitrary transducers such as infrared ray sensor.

(action)

Next, the action of the induction heating cooking instrument 100 of execution mode 1 is described.

First, illustrate that the firepower by utilizing operating portion 40 to set carries out the action of the situation of induction heating to the heating object 5 loaded on the heating gate of top board 4.

If load heating object 5 by user on heating gate, and carried out heating the instruction starting (firepower input) to operating portion 40, then control part 45 (load identifying unit) carries out load determination processing.

Herein, the material becoming the heating object 5 (pot) of load is roughly classified into high resistance nonmagnetic substance and the low resistance such as aluminium, the copper nonmagnetic substances such as the magnetic material such as iron, SUS430, SUS304.

As shown in Figure 3, according to the material of the pot load loaded on the top plate 4, coil current is different with the relation of input current.Control part 45 carries out tabular in storage inside to the relation of the coil current shown in Fig. 3 and input current in advance and the load obtained judges form.By judging form at storage inside load, can with cheap Structure composing load identifying unit.

In load determination processing, the control part 45 specific drive singal that load judges drives inverter circuit 23, from the output signal of input electric cur-rent measure unit 25a, detects input current.In addition, meanwhile, control part 45 from the output signal of coil current detecting unit 25b, magnetic test coil electric current.Control part 45 is according to the coil current detected and input current and represent that the load of relation of Fig. 3 judges form, judges the material of the heating object (pot) 5 loaded.Like this, relevant according to input current and coil current of control part 45 (load identifying unit), judges the material of the heating object 5 loaded above heater coil 11a.

After load determination processing more than having carried out, control part 45 carries out the control action based on load result of determination.

When load result of determination is low resistance nonmagnetic substance, the induction heating cooking instrument 100 of present embodiment 1 can not heat, so can not heat reporting unit 42 report, urges user to change pot.

In addition, even if under load result of determination is uncharge situation, also can not heat reporting unit 42 report, urge user to load pot.

When load result of determination be magnetic material or high resistance nonmagnetic substance, these pots are the materials that can heat with the induction heating cooking instrument 100 of present embodiment 1, so control part 45 determines the driving frequency corresponding with the pot material that determined.This driving frequency is set to the frequency higher than resonance frequency, can not become excessive to make input current.About the decision of this driving frequency, can by referring to such as deciding with the form etc. setting frequency corresponding to firepower with the material of heating object 5.

Control part 45 fixes determined driving frequency, drives inverter circuit 23, starts induction heating action.In addition, under the state securing driving frequency, the duty ratio (ON (conducting) OFF (disconnection) ratio) of the switch element of inverter circuit 23 also becomes the state secured.

The correlation diagram of the relative driving frequency of input current when Fig. 4 is the variations in temperature of the heating object of the induction heating cooking instrument of execution mode 1.In the diagram, fine rule is heating object 5 (pot) is characteristic during low temperature, the characteristic that thick line is heating object 5 when being high temperature.

As shown in Figure 4, the reason that characteristic changes according to the temperature of heating object 5 is, because temperature rises, the resistivity of heating object 5 rises, and magnetic susceptibility reduces, thus the change of the magnetic coupling of heater coil 11a and heating object 5.

In the control part 45 of the induction heating cooking instrument 100 of present embodiment 1, determine, for driving frequency, to fix this driving frequency and carry out control inverter circuit 23 by becoming the high frequency of maximum frequency than the input current shown in Fig. 4.

Fig. 5 is the figure of the part shown in dotted line being exaggerated Fig. 4.

If the fixing driving frequency corresponding with the pot material that determined in above-mentioned load determination processing carrys out control inverter circuit 23, then along with heating object 5 becomes high temperature from low temperature, input current value (operating point) under this driving frequency is changed to a B from an A, temperature with heating object 5 rises, and input current reduces gradually.

Now, control part 45, under the state of driving frequency securing inverter circuit 23, obtains the variable quantity (time variations) of per stipulated time of input current, according to the variable quantity of this per stipulated time, and the variations in temperature of detection heating object 5.

Therefore, no matter what the material of heating object 5 is, the variations in temperature of heating object 5 can both be detected.In addition, can by the change of input current, the variations in temperature of detection heating object 5, so compared to temperature sensor etc., can detecting temperature change at high speed.

In addition, judge the material of the heating object 5 loaded above heater coil 11a, according to the material of heating object 5, determine the driving frequency of inverter circuit 23, by this driving frequency, inverter circuit 23 is driven.Therefore, it is possible to by the driving frequency corresponding with the material of heating object 5, fix inverter circuit 23 and drive, the increase of input current can be suppressed.Therefore, it is possible to suppress the high temperature of inverter circuit 23, reliability can be improved.

(pattern 1 of heating up water)

Next, illustrate by operating portion 40, have selected the action of the situation of the pattern of heating up water of the action of heating up water of the water carrying out putting into heating object 5 as cooking menu (pattern).

Control part 45, in the same manner as above-mentioned action, carries out load determination processing, determines the driving frequency corresponding with the pot material that determined, and fixing determined driving frequency, drives inverter circuit 23, implements induction heating action.Then, by the time variations of input current, control part 45 judges that boiling completes.Herein, by Fig. 6, the change of elapsed time when carrying out the heating up water of water and each characteristic is described.

Fig. 6 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 1 is shown, temperature, input current and the relation of time.In figure 6, show the change dropping into water and elapsed time of having carried out when heating up water and each characteristic in heating object 5, Fig. 6 (a) illustrates driving frequency, and Fig. 6 (b) illustrates temperature (water temperature), and Fig. 6 (c) illustrates input current.

As shown in Fig. 6 (a), fixed drive frequency carries out the control of inverter circuit 23.As shown in Fig. 6 (b), the temperature (water temperature) of heating object 5 is until boiling is risen gradually, if seethed with excitement, temperature becomes constant.As shown in Fig. 6 (c), according to the rising of the temperature of heating object 5, input current reduces gradually, if water boiling and temperature becomes constant, then input current also becomes constant.That is, if input current becomes constant, then water seethes with excitement and has heated up water.

Thus, control part 45 in present embodiment is under the state of driving frequency securing inverter circuit 23, obtain the variable quantity (time variations) of per stipulated time of input current, when the variable quantity of this per stipulated time becomes below setting, be judged as having heated up water.

In addition, about the information of setting, both can set control part 45 in advance, also can from input such as operating portion 40 grade.

Then, control part 45 operation report unit 42 reports the meaning of having heated up water.Herein, as reporting unit 42, the display carrying out having seethed with excitement in display part 41 etc. or use loud speaker (not shown) to report user with sound, its mode is not particularly limited.

As described above, setting water action of heating up water heat up water in pattern, under the state securing the driving frequency of inverter circuit 23, obtain the variable quantity of per stipulated time of input current, when the variable quantity of this per stipulated time becomes below setting, the meaning of having been heated up water by reporting unit 42 report.

Therefore, it is possible to promptly report having heated up water of water, induction heating cooking instrument easy to use can be obtained.

(pattern 2 of heating up water)

Next, other control action that be have selected the situation of the pattern of heating up water by operating portion 40 is described.

Control part 45, in the same manner as above-mentioned action, carries out load determination processing, determines the driving frequency corresponding with the pot material that determined, and fixing determined driving frequency, drives inverter circuit 23, implements induction heating action.Then, control part 45, by the time variations of input current, judges that boiling completes.

And then, when the variable quantity of per stipulated time that control part 45 has been obtained under the state of driving frequency securing inverter circuit 23 becomes below setting, remove the fixing of driving frequency, make the driving frequency of inverter circuit 23 variable, make the High frequency power of heater coil 11a supply variable.The details of such action is described by Fig. 7, Fig. 8.

Fig. 7 is the figure of the part shown in dotted line being exaggerated Fig. 4.

Fig. 8 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 1 is shown, temperature, input current and the relation of time.In fig. 8, the change dropping into water and elapsed time of having carried out when heating up water and each characteristic in heating object 5 is shown, Fig. 8 (a) illustrates driving frequency, and Fig. 8 (b) illustrates temperature (water temperature), and Fig. 8 (c) illustrates input current.

In the same manner as the action of above-mentioned pattern 1 of heating up water, if fixed drive frequency and start heat (Fig. 8 (a)), then the temperature (water temperature) of heating object 5 rises gradually until seethe with excitement (Fig. 8 (b)).In the control fixing this driving frequency, as shown in Figure 7, the input current value (operating point) under this driving frequency is changed to a B from an E, and the temperature with heating object 5 rises, and input current reduces gradually.

If water seethes with excitement and temperature becomes constant, then input current also becomes constant (Fig. 8 (c)).Thus, at time t1, control part 45 is judged to be that the variable quantity of per stipulated time of input current becomes below setting, is judged as having heated up water.

Next, control part 45 removes the fixing of driving frequency, makes the driving frequency of inverter circuit 23 increase, thus reduces input current, and the High frequency power (firepower) to heater coil 11a supplies is reduced.Now, even if improve driving frequency and make firepower reduce, temperature also reduces hardly, so as shown in Figure 7, operating point moves (change) to some C from a B.

Then, control part 45 fixes the driving frequency of inverter circuit 23 again, by the firepower reduced, continues heating.

When heating up water (boiling of water), even if more than needed for being improved by firepower, water temperature also can not become more than 100 DEG C, even if so improve driving frequency and make firepower reduce, also can water temperature be kept.

Like this, when the variable quantity of per stipulated time of input current becomes below setting, due to the driving of control inverter circuit 23, and reduce the High frequency power that heater coil 11a is supplied, so input electric power can be suppressed to realize energy-saving.

In addition, at time t1, control part 45 improves the driving frequency to inverter circuit 23, and has been heated up water by reporting unit 42 pairs of user's reports.In addition, about the report to user, both can raising driving frequency before, also can raising driving frequency after.

By having been heated up water by report, user has dropped into cooking material to heating object 5 (pot) sometimes.Herein, with the situation having dropped into cooking material at time t2 in heating object 5 for example is described.

If at time t2, in heating object 5, dropped into cooking material, then, as shown in Fig. 8 (b), the temperature of heating object 5 reduces.Reducing about this temperature, is such as when low temperature, reduce more significantly as frozen food at the cooking material dropped into.In addition, reduce with this temperature, as shown in Fig. 8 (c), input current sharply increases.

Now, as shown in Figure 7, operating point moves (change) to some D from a C.

When the variable quantity of per stipulated time that control part 45 has been obtained under the state of driving frequency securing inverter circuit 23 becomes more than 2nd setting, be judged as due to carry out food materials drop into action, water filling action etc. and temperature reduces (time t3).

In addition, about the information of the 2nd setting, both can set control part 45 in advance, also can from input such as operating portion 40 grade.

Then, at time t3, control part 45 removes the fixing of driving frequency, the driving frequency of inverter circuit 23 is reduced, thus input current is increased, and the High frequency power (firepower) to heater coil 11a supplies is increased.Thus, as shown in Figure 7, operating point moves (change) to some E from a D.

Then, control part 45 fixes the driving frequency of inverter circuit 23 again, by the firepower added, continues heating.

At time t3, under the state of low temperature, driving frequency is reduced, so input current rises further, but the rising of adjoint temperature, input current reduces gradually (Fig. 8 (b), (c)).Now, as shown in Figure 7, operating point moves (change) to some B from an E.

Thus, at time t4, control part 45 is judged to be that the variable quantity of per stipulated time of input current becomes below setting, is again judged as having heated up water.

Next, control part 45 removes the fixing of driving frequency, makes the driving frequency of inverter circuit 23 again increase, thus input current is reduced, and the High frequency power (firepower) to heater coil 11a supplies is reduced.After, above-mentioned action repeatedly, till the operation carrying out heating stopping (pattern of heating up water terminates) from operating portion 40.

By such action, the operating point of Fig. 7 moves (change) according to the order of an an an E → B → C.

As described above, when the variable quantity of the per stipulated time obtained under the state of driving frequency securing inverter circuit 23 becomes more than 2nd setting, remove the fixing of driving frequency, the driving of control inverter circuit 23, High frequency power to heater coil 11a supplies is increased, thus the temperature that promptly can detect heating object 5 reduces and makes firepower increase, the short time cooking can be realized.In addition, by realizing the short time cooking, can be easy to use, can energy-saving be realized.

In addition, such as, when having dropped into food materials after seething with excitement, when having carried out the filling of water, if controlled when fixed drive frequency, then exist and cannot obtain fully hankering required firepower to adding of food materials (water), cooking length of time extends and usability is deteriorated, and the problem that the use amount of power of entirety increases.

In addition, in the above description, describe the mode controlling firepower by changing driving frequency, but the duty ratio (ONOFF ratio) of the switch element by changing inverter circuit 23 also can be used to control the mode of firepower.

(fried pattern)

Next, action during the fried cooking carrying out the oil in heating object 5 being heated to set point of temperature is described.

When heating oil, different from the boiling of water, even if fixed drive frequency and Sustainable Control, the change of input current can not become constant, and the constant temperature of oil rises, and in the worst case, has the possibility that oil is on fire.

In the present embodiment, as shown in Figure 2, detect the detection of the variable quantity of input current by the thermistor also by the temperature of use detection heating object 5, infrared ray sensor equitemperature probe unit 30 and utilize the temperature sensing of temperature detecting unit 30, realizing the induction heating cooking instrument that inhibit the overheated reliability of oil high.

If by operating portion 40, fried pattern is have selected as cooking menu (pattern), then control part 45 carries out load determination processing as described above, determines the driving frequency being suitable for the material of heating object 5, and fixing determined driving frequency carries out induction heating action.

In addition, by the value adding the input current hankered and the temperature that detected by temperature detecting unit 30 are outputted to control part 45, control part 45 can the relation of storing temperature and input current.

If the temperature detected by temperature detecting unit 30 reaches the temperature (set point of temperature) being suitable for the fried cooking, then control part 45 removes the fixing of driving frequency, to keep the mode of its temperature, makes driving frequency rise gradually and firepower is reduced.Now, namely when making driving frequency rise gradually, with the driving frequency by control part 45 storage change simultaneously, the value storing the input current detected by input electric cur-rent measure unit 25a with control part 45 and the temperature detected by temperature detecting unit 30.

By reporting unit 42 couples of users, control part 45 reports that the preheating of the fried cooking completes, and again fix the driving frequency of inverter circuit 23, by the firepower reduced, continues heating.In addition, about the report to user, both can raising driving frequency before, also can raising driving frequency after.

If after reporting preheating and completing, dropped into food materials by user to heating object 5, then the temperature of oil reduces.When the food materials dropped into are frozen food, large with the temperature difference of oil, if so the amount of the food materials dropped into is many, then oil temperature sharply reduces.

When the variable quantity of per stipulated time of the input current that control part 45 has been obtained under the state securing the driving frequency of inverter circuit 23 or coil current becomes more than 3rd setting, the driving of control inverter circuit 23, makes the High frequency power to heater coil 11a supplies increase.

In addition, about the information of the 3rd setting, both can set control part 45 in advance, also can from input such as operating portion 40 grade.

As described above, when the detecting temperature of temperature detecting unit 30 has exceeded set point of temperature, High frequency power to heater coil 11a supplies is reduced, when the variable quantity of per stipulated time that obtained under the state of driving frequency securing inverter circuit 23, input current becomes more than 3rd setting, the driving of control inverter circuit 23, makes the High frequency power to heater coil 11a supplies increase.Therefore, it is possible to suppress the temperature of oil to reduce, keep the temperature being suitable for the fried cooking, so the induction heating cooking instrument easy to use of the time shortening the fried cooking can be obtained.

In addition, when by means of only such as thermistor, infrared ray sensor equitemperature probe unit 30 have detected temperature, there is the problem of the detection generation delay of the variations in temperature of oil when food materials drop into.In the present embodiment, driving frequency is fixed the input current under controlling and is sharply changed, so the variable quantity by detecting input current, the temperature that can detect oil reduces.

(structure example of other drive circuit)

Next, the example employing other drive circuit is described.

Drive circuit 50 shown in Fig. 9 is the structures that the structure shown in Fig. 2 be addition of to resonating capacitor 24b.In addition, other structure is identical with Fig. 2, adds prosign to a part.

As mentioned above, constitute resonant circuit by heater coil 11a and resonating capacitor, so by the maximum fire (maximum input electric power) needed for induction heating cooking instrument, determine the electric capacity of resonating capacitor.In the drive circuit 50 shown in Fig. 9, by being connected in parallel resonating capacitor 24a and 24b, respective electric capacity can being made to become half, even if when employing 2 resonating capacitors, also can obtain cheap control circuit.

In addition, by coil current detecting unit 25b being configured at the resonating capacitor 24a side in the resonating capacitor be connected in parallel, the electric current flow through in coil current detecting unit 25b becomes the half of the electric current flow through in heater coil 11a, so the coil current detecting unit 25b of small-sized/small capacitances can be used, small-sized and the control circuit of cheapness can be obtained, cheap induction heating cooking instrument can be obtained.

Execution mode 2.

Figure 10 is the figure of the driving frequency of the induction heating cooking instrument that execution mode 2 is shown, temperature, input current and the relation of time.In Fig. 10, the change dropping into water and elapsed time of having carried out when heating up water and each characteristic in heating object 5 is shown, Figure 10 (a) illustrates driving frequency, Figure 10 (b) illustrates temperature (end temperature of heating object 5), and Figure 10 (c) illustrates input current.

(mode 3 of heating up water)

Other control action that be have selected the situation of the pattern of heating up water by operating portion 40 is described.

Control part 45, in the same manner as the action described in execution mode 1, carries out load determination processing, determines the driving frequency corresponding with the pot material that determined, and fixing determined driving frequency, drives inverter circuit 23, implements induction heating action.Then, control part 45, by the time variations of input current, judges that boiling completes.

And then, when the variable quantity of per stipulated time that control part 45 has been obtained under the state of driving frequency securing inverter circuit 23 becomes below setting, remove the fixing of driving frequency, make the driving frequency of inverter circuit 23 variable, make the High frequency power of heater coil 11a supply variable.By Figure 10, the details of such action is described.

In the same manner as the action of above-mentioned pattern 1,2 of heating up water, if fixed drive frequency and start heating (Figure 10 (a)), then till the water boiling of rising gradually in heating object 5 of the end temperature of heating object 5 (Figure 10 (b)).In the control fixing this driving frequency, the temperature with heating object 5 rises, and input current reduces gradually.

If water seethes with excitement and temperature becomes constant, then input current also becomes constant (Figure 10 (c)).Thus, at time t1, control part 45 is judged to be that the variable quantity of per stipulated time of input current becomes below setting, is judged as having heated up water.

Next, control part 45 removes the fixing of driving frequency, makes the driving frequency of inverter circuit 23 increase, thus reduces input current, and the High frequency power (firepower) to heater coil 11a supplies is reduced.Now, even if improve driving frequency and make firepower reduce, temperature also reduces hardly.Then, control part 45 fixes the driving frequency of inverter circuit 23 again, by the firepower reduced, continues heating.

When heating up water (boiling of water), even if more than needed for being brought up to by firepower, water temperature also can not become more than 100 DEG C, even if so improve driving frequency and make firepower reduce, also can water temperature be kept.

Even if when report heated up water, user also places sometimes as former state, water constantly boiling.Herein, with at time t2, the vaporized situation of the water in heating object 5 is example explanation.

When having water in heating object 5, the temperature (temperature in the bottom of a pan) of heating object 5 is roughly equal to water temperature or passes with the temperature higher a little than water temperature.That is, in the boiling of water, the temperature constant of heating object 5 is about 100 DEG C.

If at time t2, the water evaporation in heating object 5, then the temperature of heating object 5 sharply rises, and with the rising of the temperature of heating object 5, as shown in Figure 10 (c), input current sharply reduces.

Under the variable quantity (reducing amount) of per stipulated time that control part 45 has been obtained under the state of driving frequency securing inverter circuit 23 becomes the situation (reducing the situation of more than the 4th setting) of more than the 4th setting, be judged as evaporation of water (time t3).

In addition, about the information of the 4th setting, both can set control part 45 in advance, also can from input such as operating portion 40 grade.

Then, at time t3, control part 45 stops to heater coil 11a supply high frequency electric power (firepower).Now, control part 45 reports evaporation of water by reporting unit 42 couples of users.

As described above, under the reducing amount (variable quantity) of the per stipulated time obtained under the state of driving frequency securing inverter circuit 23 becomes the situation (reducing the situation of more than the 4th setting) of more than the 4th setting, remove the fixing of driving frequency, control in the mode of the driving stopping inverter circuit 23, stop to heater coil 11a supply high frequency electric power, thus the sharply rising of the temperature of heating object 5 can be suppressed, the induction heating cooking instrument that fail safe is high can be obtained.In addition, by reporting evaporation of water to user, fail safe can be improved further, induction heating cooking instrument easy to use can be obtained.

In addition, such as, even if when the thermistor of contact, contactless infrared ray sensor are used as temperature detecting unit 30, also evaporation of water can be detected, but be difficult to the variations in temperature sharply of the heating object 5 that instantaneous detection and evaporation of water accompany, the danger (problem) that the temperature that there is heating object 5 sharply rises.

In addition, each pattern described in above-mentioned execution mode 1 and 2 can also be combined in.Such as, the pattern of the action of the action being combined with the pattern of heating up water 2 and mode 3 of heating up water can also be become.

In addition, in above-mentioned execution mode 1 and 2, describe the example of the variable quantity detecting the input current detected by input electric cur-rent measure unit 25a, but also can replace input current and detect the variable quantity of the coil current detected by coil current detecting unit 25b, also can detect the variable quantity of input current and this two side of coil current.

In addition, in above-mentioned execution mode 1 and 2, describe the inverter circuit 23 of semi-bridge type, but also can be the use of the structure of inverter etc. of bridge-type, a stone series resonance type.

And then, describe the mode using the relation of coil current and primary current in the load of pot material judges, but the resonance voltage at the two ends by detecting resonating capacitor also can be used to carry out the mode of load judgement, and the mode that load judges does not specially require.

Execution mode 3.

In present embodiment 3, the details of the drive circuit 50 in above-mentioned execution mode 1 and 2 is described.

Figure 11 is the figure of a part for the drive circuit of the induction heating cooking instrument that execution mode 3 is shown.In addition, in fig. 11, illustrate only the structure of a part for the drive circuit 50 of above-mentioned execution mode 1 and 2.

As shown in figure 11, inverter circuit 23 possesses the branch of diode 23c, 23d that 1 group is included in 2 switch elements (IGBT23a, 23b) being connected in series between positive and negative busbar and be connected to respectively with this switch element anti-parallel connection.

For IGBT23a and IGBT23b, carry out ONOFF driving by the drive singal exported from control part 45.

Control part 45 makes IGBT23b become OFF state during making IGBT23a become ON, makes IGBT23b become ON state during making IGBT23a become OFF, exports the drive singal alternately becoming ONOFF.

Thus, form by IGBT23a and IGBT23b the half-bridge inverter driving heater coil 11a.

In addition, " the half-bridge inverter circuit " in the present invention is made up of IGBT23a and IGBT23b.

Control part 45, according to input electric power (firepower), inputs the drive singal of high frequency to IGBT23a and IGBT23b, adjustment adds thermal output.About the drive singal exported to IGBT23a and IGBT23b, variable in the scope of the driving frequency higher than the resonance frequency of the load circuit be made up of heater coil 11a and resonating capacitor 24a, control to make the mode that the current ratio flow through in load circuit flows through to the voltage that load circuit applies with the phase place postponed.

Next, the control action of the input electric power (firepower) of the driving frequency utilizing inverter circuit 23 and duty ratio is described.

Figure 12 is the figure of an example of the drive singal of the half-bridge circuit that execution mode 3 is shown.Figure 12 (a) is the example of the drive singal of each switch under high firepower state.Figure 12 (b) is the example of the drive singal of each switch under low firepower state.

Control part 45, to IGBT23a and IGBT23b of inverter circuit 23, exports the drive singal of the high frequency higher than the resonance frequency of load circuit.

By making the changeable frequency of this drive singal, the output increase and decrease of inverter circuit 23.

Such as, if as shown in Figure 12 (a), driving frequency is reduced, then to the frequency of the high-frequency current that heater coil 11a supplies close to the resonance frequency of load circuit, the input electric power to heater coil 11a increases.

In addition, if as shown in Figure 12 (b), make driving frequency increase, then to the frequency of the high-frequency current that heater coil 11a supplies away from the resonance frequency of load circuit, the input electric power to heater coil 11a reduces.

And then, control part 45 can also by with utilize above-mentioned driving frequency variable input electric power control together with, make the variable duty ratio of IGBT23a and IGBT23b of inverter circuit 23, carry out the application time of the output voltage of control inverter circuit 23, control the input electric power to heater coil 11a.

When making firepower increase, increasing the ratio (duty ratio) of the ON time (the OFF time of IGBT23b) of the IGBT23a in 1 cycle of drive singal, and the voltage application time width in 1 cycle is increased.

In addition, when making firepower reduce, reducing the ratio (duty ratio) of the ON time (the OFF time of IGBT23b) of the IGBT23a in 1 cycle of drive singal, and the voltage application time width in 1 cycle is reduced.

In the example of Figure 12 (a), illustrate the situation of the ON time T11a (the OFF time of IGBT23b) of the IGBT23a in 1 cycle T 11 of the drive singal situation (duty ratio be 50%) identical with the ratio of the OFF time T11b (the ON time of IGBT23b) of IGBT23a.

In addition, in the example of Figure 12 (b), illustrate the situation of the ON time T12a (the OFF time of IGBT23b) of the IGBT23a in 1 cycle T 12 of the drive singal situation (duty ratio be 50%) identical with the ratio of the OFF time T12b (the ON time of IGBT23b) of IGBT23a.

During the variable quantity of per stipulated time that control part 45 describes in above-mentioned execution mode 1 and 2, that obtain input current (or coil current), under the state of driving frequency securing inverter circuit 23, become the state duty ratio of IGBT23a and IGBT23b of inverter circuit 23 secured.

Thereby, it is possible under being constant state to the input electric power of heater coil 11a, obtain the variable quantity of per stipulated time of input current (or coil current).

Execution mode 4.

In present embodiment 4, the inverter circuit 23 employing full-bridge circuit is described.

Figure 13 is the figure of a part for the drive circuit of the induction heating cooking instrument that execution mode 4 is shown.In addition, in fig. 13, illustrate only the difference with the drive circuit 50 of above-mentioned execution mode 1 and 2.

In present embodiment 4, be provided with 2 heater coils for 1 heating gate.About 2 heater coils, such as, diameter is different respectively, the configuration of concentric circles ground., heater coil little for diameter is called interior loop 11b herein, heater coil large for diameter is called exterior loop 11c.

In addition, the quantity of heater coil and configuration are not limited thereto.Such as, also can be the structure configuring multiple heater coil around the heater coil of the central authorities being configured at heating gate.

Inverter circuit 23 possesses 3 groups by 2 switch elements (IGBT) be connected in series between positive and negative busbar and the branch formed with the diode that this switch element is connected to respectively anti-parallel connection.In addition, afterwards, 1 in the branch of 3 groups group is called community branch, is called interior loop branch and exterior loop branch by other 2 groups.

Community branch is the branch be connected to interior loop 11b and exterior loop 11c, is made up of IGBT232a, IGBT232b, diode 232c and diode 232d.

Interior loop is the branch being connected to interior loop 11b with branch, is made up of IGBT231a, IGBT231b, diode 231c and diode 231d.

Exterior loop is the branch being connected to exterior loop 11c with branch, is made up of IGBT233a, IGBT233b, diode 233c and diode 233d.

About IGBT232a and IGBT232b, IGBT231a and IGBT231b of interior loop with branch, IGBT233a and IGBT233b of exterior loop branch of community branch, carry out ONOFF driving by the drive singal exported from control part 45.

Control part 45 makes IGBT232b become OFF state during making the IGBT232a of community branch become ON, makes IGBT232b become ON state during making IGBT232a become OFF, exports the drive singal alternately becoming ONOFF.

Similarly, control part 45 exports and makes IGBT233a and IGBT233b of IGBT231a and IGBT231b of interior loop branch, exterior loop branch alternately become the drive singal of ONOFF.

Thus, by community branch and interior loop branch, form the full-bridge inverter driving interior loop 11b.In addition, by community branch and exterior loop branch, form the full-bridge inverter driving exterior loop 11c.

In addition, to be made up of " full-bridge inverter circuit " in the present invention with branch community branch and interior loop.In addition, to be made up of " full-bridge inverter circuit " in the present invention with branch community branch and exterior loop.

The load circuit be made up of interior loop 11b and resonating capacitor 24c be connected to community branch output point (tie point of IGBT232a and IGBT232b), and the output point (tie point of IGBT231a and IGBT231b) of interior loop branch between.

The load circuit be made up of exterior loop 11c and resonating capacitor 24d be connected to community branch output point, and the output point (tie point of IGBT233a and IGBT233b) of exterior loop branch between.

Interior loop 11b is the circular ground little heater coil of the profile that reeled, is configured with exterior loop 11c in its periphery.

The coil current flow through in interior loop 11b is detected by coil current detecting unit 25c.The voltage signal suitable with the peak value of heating coil current, as the peak value of the electric current flow through in interior loop 11b, is outputted to control part 45 by coil current detecting unit 25c test example.

By coil current detecting unit 25d, detect the coil current flow through in exterior loop 11c.Coil current detecting unit 25d such as detects the peak value of the electric current flow through in exterior loop 11c, and the voltage signal suitable with the peak value of heating coil current is outputted to control part 45.

Control part 45 is according to input electric power (firepower), and the switch element (IGBT) to each branch inputs the drive singal of high frequency, and adjustment adds thermal output.

About the drive singal exported with the switch element of branch to community branch and interior loop, variable in the scope of the driving frequency higher than the resonance frequency of the load circuit be made up of interior loop 11b and resonating capacitor 24c, control to make the mode that the current ratio flow through in load circuit flows through to the voltage that load circuit applies with the phase place postponed.

In addition, about the drive singal exported with the switch element of branch to community branch and exterior loop, variable in the scope of the driving frequency higher than the resonance frequency of the load circuit be made up of exterior loop 11c and resonating capacitor 24d, control to make the mode that the current ratio flow through in load circuit flows through to the voltage that load circuit applies with the phase place postponed.

Next, the control action of the input electric power (firepower) of the branch's phase difference each other utilizing inverter circuit 23 is described.

Figure 14 (a) is the example of the drive singal of each switch under high firepower state and the energising timing of each heater coil.

Figure 14 (b) is the example of the drive singal of each switch under low firepower state and the energising timing of each heater coil.

In addition, Figure 14 (a) and the timing of the energising shown in (b) have relation with the potential difference of the output point (tie point of IGBT and IGBT) of each branch, the output point of relative interior loop branch and the output point of exterior loop branch is represented, the state that the output point of community branch is lower with " ON ".In addition, represent the output point of relative interior loop branch and the output point of exterior loop branch with " OFF ", the state of the state that the output point of community branch is higher and same potential.

As shown in figure 14, control part 45, to IGBT232a and IGBT232b of community branch, exports the drive singal of the high frequency higher than the resonance frequency of load circuit.

In addition, phase place is outputted to IGBT231a and IGBT231b of interior loop branch, IGBT233a and IGBT233b of exterior loop branch than the drive singal that the drive singal of community branch shifts to an earlier date by control part 45.In addition, the frequency of the drive singal of each branch is same frequency, and duty ratio is also identical.

To the output point (tie point of IGBT and IGBT) of each branch, according to the ONOFF state of IGBT and IGBT, high frequency ground switches the positive bus-bar current potential or negative busbar current potential that export as the output of DC power supply circuit.Thus, to interior loop 11b, apply the output point of community branch and the potential difference of the interior loop output point of branch.In addition, to exterior loop 11c, apply the output point of community branch and the potential difference of the exterior loop output point of branch.

Therefore, by making the phase difference increase and decrease of the drive singal to community branch and the drive singal to interior loop branch and exterior loop branch, the high frequency voltage that interior loop 11b and exterior loop 11c are applied can be adjusted, the high frequency output electric current that flows through in interior loop 11b and exterior loop 11c and input current can be controlled.

When making firepower increase, increase the voltage application time width in 1 cycle by the phase place α increased between branch.In addition, the upper limit of the phase place α between branch is the situation of anti-phase (phase difference 180 °), and output voltage waveforms now becomes substantially rectangular ripple.

In the example of Figure 14 (a), the phase place α illustrated between branch is the situation of 180 °.In addition, the duty ratio illustrating the drive singal of each branch is the situation that the ON time T13a in the situation of 50%, i.e. 1 cycle T 13 is identical with the ratio of OFF time T13b.

In this case, the interior loop 11b in 1 cycle T 14 of drive singal, the energising ON time width T14a of exterior loop 11c and energising OFF time width T14b become identical ratio.

When making firepower reduce, compared to high firepower state, by the phase place α reduced between branch, the voltage application time width in 1 cycle is reduced.In addition, about the lower limit of the phase place α between branch, according to the relation of the phase place with the electric current such as flow through in load circuit when TURNON (connection) etc., be set as to flow through super-high-current in switch element and the level destroyed.

In the example of Figure 14 (b), illustrate the situation reducing the phase place α between branch compared to Figure 14 (a).In addition, the frequency of the drive singal of each branch and duty ratio identical with Figure 14 (a).

In this case, the interior loop 11b in 1 cycle T 14 of drive singal, the energising ON time width T14a of exterior loop 11c become time corresponding to phase place α between branch.

Like this, can branch's phase difference each other be passed through, control the input electric power (firepower) to interior loop 11b, exterior loop 11c.

In addition, in the above description, describe and make interior loop 11b and exterior loop 11c all carry out adding thermally operated situation, but also can stop the driving of interior loop branch or exterior loop branch, and only make the one party in interior loop 11b and exterior loop 11c carry out heating action.

During the variable quantity of per stipulated time that control part 45 describes in above-mentioned execution mode 1 and 2, that obtain input current (or coil current), under the state of driving frequency securing inverter circuit 23, the state that the duty ratio of the phase place α between becoming branch and the switch element of each branch secures.In addition, other action is identical with above-mentioned execution mode 1 or 2.

Thereby, it is possible under being constant state to the input electric power of interior loop 11b, exterior loop 11c, obtain the variable quantity of per stipulated time of input current (or coil current).

In addition, in present embodiment 4, by coil current detecting unit 25c and coil current detecting unit 25d, detect the coil current flow through in the coil current flow through in interior loop 11b and exterior loop 11c respectively.

Therefore, when making interior loop 11b and exterior loop 11c all carry out heating action, even if the one party in coil current detecting unit 25c and coil current detecting unit 25d due to fault etc. and cannot magnetic test coil current value, also can by the detected value of the opposing party, the variable quantity of per stipulated time of magnetic test coil electric current.

In addition, the variable quantity that control part 45 also can obtain per stipulated time of the coil current detected by coil current detecting unit 25c respectively and the variable quantity of per stipulated time of coil current detected by coil current detecting unit 25d, use the large side in each variable quantity, carry out each judgement action described in above-mentioned execution mode 1 and 2.In addition, also can use the mean value of respective variable quantity, carry out each judgement action described in above-mentioned execution mode 1 and 2.

By carrying out such control, even if the some accuracy of detection in coil current detecting unit 25c and coil current detecting unit 25d are low, the variable quantity of per stipulated time of coil current also more precisely can be obtained.

In addition, in above-mentioned execution mode 1 ~ 4, as an example of induction heating cooking instrument of the present invention, with IH cooking heater for example is illustrated, but the present invention is not limited thereto.The present invention can be applied to the arbitrary induction heating cooking instrument that the electric rice cooker being carried out cooking by induction heating etc. adopts induction heating mode.

Claims

1. an induction heating cooking instrument, is characterized in that, possesses:

Heater coil, carries out induction heating to heating object;

Drive circuit, to described heater coil supply high frequency electric power; And

Control part, controls the driving of described drive circuit, controls the High frequency power supplied described heater coil,

Described control part

Under the state of the duty ratio of the switch element of the driving frequency and described drive circuit that secure described drive circuit, according to the variable quantity of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit, detect the variations in temperature of described heating object.

2. induction heating cooking instrument according to claim 1, is characterized in that,

Described control part

When described variable quantity becomes below threshold value,

Control the driving of described drive circuit, make the High frequency power that supplies described heater coil variable.

3. the induction heating cooking instrument according to claims 1 or 2, is characterized in that,

Described control part

When described variable quantity becomes below threshold value, remove the fixing of described driving frequency,

Improve the driving frequency of described drive circuit, the High frequency power to described heater coil supplies is reduced.

4. induction heating cooking instrument according to claim 1 and 2, is characterized in that, possesses:

Operating portion, carries out the selection operation of pattern; And

Reporting unit,

Described control part

When have selected the pattern of heating up water of action of heating up water of setting water as described pattern, described drive circuit is driven,

Under the state of driving frequency securing described drive circuit, when the 5th variable quantity of at least one party in described input current and described coil current becomes below threshold value, to be heated up water the meaning completed by the report of described reporting unit.

5. induction heating cooking instrument according to claim 1 and 2, is characterized in that,

Possess load identifying unit, this load identifying unit carries out the load determination processing of described heater coil,

Described control part, according to the result of determination of described load identifying unit, makes described drive circuit drive.

6. induction heating cooking instrument according to claim 5, is characterized in that,

Described load identifying unit

Relevant according to described input current and described coil current, carries out the load determination processing of described heating object.

7. induction heating cooking instrument according to claim 1 and 2, is characterized in that,

Described drive circuit by have at least 2 by 2 switch elements in series the full-bridge inverter circuit of branch that is connected to form,

Described control part secure described full-bridge inverter circuit described switch element driving frequency state under, become and secure the driving phase difference of described switch element each other of described 2 branches and the state of the duty ratio of described switch element.

8. induction heating cooking instrument according to claim 1 and 2, is characterized in that,

Described drive circuit by have by 2 switch elements in series the half-bridge inverter circuit of branch that is connected to form.

9. an induction heating cooking instrument, is characterized in that, possesses:

Heater coil, carries out induction heating to heating object;

Described control part

Under the state of driving frequency securing described drive circuit, the 2nd variable quantity of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit adds more than 2nd threshold value,

Control the driving of described drive circuit, the High frequency power to described heater coil supplies is increased.

10. induction heating cooking instrument according to claim 9, is characterized in that,

Described control part, by the variable duty ratio of the driving frequency or switch element that make described drive circuit, makes the High frequency power that supplies described heater coil variable.

11. induction heating cooking instruments according to claim 9 or 10, is characterized in that possessing:

Operating portion, carries out the selection operation of pattern; And

Reporting unit,

Described control part

12. induction heating cooking instruments according to claim 9 or 10, is characterized in that,

13. induction heating cooking instruments according to claim 12, is characterized in that,

Described load identifying unit

14. induction heating cooking instruments according to claim 9, is characterized in that,

Described control part

Under the state of driving frequency securing described drive circuit, be set to the state of the duty ratio of the switch element securing described drive circuit.

15. induction heating cooking instruments according to claim 9 or 10, is characterized in that,

Described control part secure described full-bridge inverter circuit described switch element driving frequency state under, be set to and secure the driving phase difference of described switch element each other of described 2 branches and the state of the duty ratio of described switch element.

16. induction heating cooking instruments according to claim 9 or 10, is characterized in that,

17. 1 kinds of induction heating cooking instruments, is characterized in that possessing:

Heater coil, carries out induction heating to heating object;

Described control part

Under the state of the duty ratio of the switch element of the driving frequency and described drive circuit that secure described drive circuit, 4th variable quantity of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit reduces more than 4th threshold value

Control in the mode of the driving stopping described drive circuit, stop to described heater coil supply high frequency electric power.

18. induction heating cooking instruments according to claim 17, is characterized in that possessing:

Operating portion, carries out the selection operation of pattern; And

Reporting unit,

Described control part

19. induction heating cooking instruments according to claim 17 or 18, is characterized in that,

20. induction heating cooking instruments according to claim 19, is characterized in that,

Described load identifying unit

21. induction heating cooking instruments according to claim 17 or 18, is characterized in that,

22. induction heating cooking instruments according to claim 17 or 18, is characterized in that,

23. 1 kinds of induction heating cooking instruments, is characterized in that possessing:

Heater coil, carries out induction heating to heating object;

Described control part

Under the state of driving frequency securing described drive circuit, according to the variable quantity of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit, when described variable quantity becomes below threshold value, remove the fixing of described driving frequency

Make the driving frequency of described drive circuit increase, and the High frequency power to described heater coil supplies reduced, the driving frequency of fixing described drive circuit,

Under the state of driving frequency securing described drive circuit, the 2nd variable quantity of at least one party in described input current and described coil current adds more than 2nd threshold value, remove the fixing of described driving frequency,

The driving frequency of described drive circuit is reduced, and the High frequency power to described heater coil supplies is increased, the driving frequency of fixing described drive circuit,

Under the state of driving frequency securing described drive circuit, the 3rd variable quantity of at least one party in described input current and described coil current becomes below described threshold value, remove the fixing of described driving frequency,

Make the driving frequency of described drive circuit increase, and the High frequency power to described heater coil supplies is reduced, the driving frequency of fixing described drive circuit.

24. induction heating cooking instruments according to claim 23, is characterized in that possessing:

Operating portion, carries out the selection operation of pattern; And

Reporting unit,

Described control part

25. induction heating cooking instruments according to claim 23 or 24, is characterized in that,

26. induction heating cooking instruments according to claim 25, is characterized in that,

Described load identifying unit

27. induction heating cooking instruments according to claim 23, is characterized in that,

Described control part

28. induction heating cooking instruments according to claim 23 or 24, is characterized in that,

29. induction heating cooking instruments according to claim 23 or 24, is characterized in that,

30. 1 kinds of induction heating cooking instruments, is characterized in that possessing:

Heater coil, carries out induction heating to heating object;

Described control part

Under the state of driving frequency securing described drive circuit, the 4th variable quantity of at least one party in described input current and described coil current reduces more than 4th threshold value,

31. induction heating cooking instruments according to claim 30, is characterized in that possessing:

Operating portion, carries out the selection operation of pattern; And

Reporting unit,

Described control part

32. induction heating cooking instruments according to claim 30 or 31, is characterized in that,

33. induction heating cooking instruments according to claim 32, is characterized in that,

Described load identifying unit

34. induction heating cooking instruments according to claim 30, is characterized in that,

Described control part

35. induction heating cooking instruments according to claim 30 or 31, is characterized in that,

36. induction heating cooking instruments according to claim 30 or 31, is characterized in that,

37. 1 kinds of induction heating cooking instruments, is characterized in that possessing:

Heater coil, carries out induction heating to heating object;

Drive circuit, to described heater coil supply high frequency electric power;

Control part, controls the driving of described drive circuit, controls the High frequency power supplied described heater coil;

Operating portion, carries out the selection operation of pattern; And

Temperature detecting unit, detects the temperature of described heating object,

Described control part

When have selected as described pattern fried pattern oil being heated to set point of temperature, described drive circuit is driven,

When the detecting temperature of described temperature detecting unit has exceeded described set point of temperature, control the driving of described drive circuit, the High frequency power to described heater coil supplies reduced, the driving frequency of fixing described drive circuit,

Under the state of driving frequency securing described drive circuit, the 6th variable quantity of at least one party in the coil current flow through in the input current and described heater coil of described drive circuit adds more than 3rd threshold value,

38., according to induction heating cooking instrument according to claim 37, is characterized in that,

39., according to induction heating cooking instrument according to claim 38, is characterized in that,

Described load identifying unit

40., according to induction heating cooking instrument according to claim 37, is characterized in that,

Described control part

41. induction heating cooking instruments according to any one in claim 37-39, is characterized in that,

42. induction heating cooking instruments according to any one in claim 37-39, is characterized in that,