CN105359622B - Induction heating cooking instrument - Google Patents

Abstract

Induction heating cooking instrument of the invention is characterised by, in the state of the driving frequency for securing drive circuit (50), obtain to the input current of drive circuit (50) and the coil current that is flowed through in heating coil (11a) at least one party time variation amount (Δ I), it is the heat time (t1) below setting value to measure from starting to heating coil (11a) supply electric power to time variation amount (Δ I), the current change quantity (I1) of at least one party in the input current and coil current in during heat time (t1) and heat time (t1), control the RF power to heating coil (11a) supply.

Description

Induction heating cooking instrument

Technical field

The present invention relates to induction heating cooking instrument.

Background technology

In conventional induction heating cooking instrument, there are input current or controlled quentity controlled variable by inverter to judge to be heated The induction heating cooking instrument (see, for example patent document 1,2) of the temperature of thing.The induction heating cooking instrument of patent document 1 have with The input current of inverter is turned into constant mode and control the control unit of inverter, when have within the stipulated time regulation with On controlled quentity controlled variable change in the case of, be judged as that the temperature change of heating object suppresses greatly the output of inverter.In addition, public Open and be judged as completion of heating up water in the case of working as below the controlled quentity controlled variable change as regulation in a period of the time of regulation, in order to Reduce the output of inverter and reduce driving frequency.

In patent document 2, it is proposed that possess the input current change amount detection of the variable quantity of detection input current And the temperature of heating object is judged according to the variable quantity of the input current detected by input current change amount detection The induction heating cooking instrument of temperature determination processing unit.Disclose to work as and be judged to that heating object turns into spray in temperature determination unit In the case of blowing temp, export stop signal and stop heating.

Patent document 1：Japanese Unexamined Patent Publication 2008-181892 publications (the 0025th section, Fig. 1)

Patent document 2：Japanese Unexamined Patent Publication 5-62773 publications (the 0017th section, Fig. 1)

The content of the invention

But, the induction heating cooking instrument such as patent document 1,2, only stop when when the temperature of regulation is reached In the case of, there is the temperature control of the content that cannot carry out being suitable for heating object after the heating of heating object so Problem.That is, in the case of the temperature (such as fluidized state) that the content of heating object is remained regulation, according to being added Thermic load (initial temperature and amount of content etc.) when the heating of hot thing is initial and the heat that should supply is different.When for example In the case of substantial amounts of heat has been supplied in the case that the initial temperature of the content of heating object is high, the waste of electric power is caused, If not supplying the heat matched with it in the case where the initial temperature of the content of heating object is low, rule cannot be remained Fixed temperature.

The present invention is completed to solve problem as described above, can be according to being added its object is to provide one kind The thermic load of the content of hot thing efficiently carries out the induction heating cooking instrument of optimal operation.

The present invention provides a kind of induction heating cooking instrument, it is characterised in that possess：Heating coil, is carried out to heating object Sensing heating；Drive circuit, to the heating coil supply high frequency electric power；And control unit, control the drive of the drive circuit Dynamic, the RF power that control is supplied to the heating coil, the control unit is securing the driving frequency of the drive circuit In the state of, obtain to the input current of the drive circuit and the coil current that is flowed through in the heating coil in extremely The time variation amount (Δ I) of few one party, measurement is from beginning to the heating coil supply electric power to the time variation amount (Δ I the very first time (t1) below setting value) is turned into, in during the very first time (t1) and the very first time (t1) The input current and the coil current at least one party current change quantity (I1), control to the heater wire Enclose the RF power of supply.

In accordance with the invention it is possible to the thermic load of the content according to heating object efficiently carries out optimal operation.In addition, Can provide can carry out the good sensing of energy-conservation and convenience of insulation action while unhelpful power supply is suppressed and add Hot cooking device.

Brief description of the drawings

Fig. 1 is the exploded perspective view of the induction heating cooking instrument for showing implementation method 1.

Fig. 2 is a figure for example of the drive circuit of the induction heating cooking instrument for showing implementation method 1.

Fig. 3 is a functional block diagram for example of the control unit of the induction heating cooking instrument for showing implementation method 1.

Fig. 4 is the relation based on heating coil current and input current in the induction heating cooking instrument of implementation method 1 The load of heating object differentiates performance plot.

When Fig. 5 is the temperature change of the heating object of the induction heating cooking instrument of implementation method 1 relative to driving frequency Input current alternate figure.

Fig. 6 is the figure of the part shown in the dotted line for being exaggerated Fig. 5.

Fig. 7 is driving frequency, temperature, input electricity in the pattern 1 of heating up water of the induction heating cooking instrument for showing implementation method 1 The figure of the relation of stream and time.

Fig. 8 is driving frequency, temperature, input electricity in the pattern 2 of heating up water of the induction heating cooking instrument for showing implementation method 1 The figure of the relation of stream and time.

Fig. 9 is the figure of the part shown in the dotted line for being exaggerated Fig. 5.

Figure 10 is the flow chart of the action example of the pattern 2 of heating up water of the induction heating cooking instrument for showing implementation method 1.

Figure 11 is the flow chart of the action example of the initial water temperature detection for showing Figure 11.

Figure 12 is to show reference time and with reference to current change quantity and the figure of the relation of the thermic load of heating starting stage.

Figure 13 is driving frequency, temperature, the input in the pattern 3 of heating up water of the induction heating cooking instrument for showing implementation method 1 The figure of the relation of electric current and time.

Figure 14 is the figure of other drive circuits of the induction heating cooking instrument for showing implementation method 1.

Figure 15 is the figure of a part for the drive circuit of the induction heating cooking instrument for showing implementation method 2.

Figure 16 is a figure for example of the drive signal of the half-bridge circuit for showing implementation method 2.

Figure 17 is the figure of a part for the drive circuit of the induction heating cooking instrument for showing implementation method 3.

Figure 18 is a figure for example of the drive signal of the full-bridge circuit for showing implementation method 3.

Symbol description

1：First heating gate；2：Second heating gate；3：3rd heating gate；4：Top board；5：Heating object；11：First heating Unit；11a：Heating coil；11b：Interior loop；11c：Exterior loop；12：Second heating unit；13：3rd heating unit；21：Hand over Stream power supply；22：DC power supply circuit；22a：Diode bridge；22b：Reactor；22c：Smoothing capacity device；23：Inverter circuit； 23a、23b：IGBT；23c、23d：Diode；24a~24d：Resonating capacitor；25a：Input electric cur- rent measure unit；25b~ 25d：Coil current detection unit；30：Temperature detecting unit；31：Drive control unit；32：Load identifying unit；33：Drive Frequency setting unit；34：Curent change detection unit；35：Period measuring unit；36：Input and output control unit；40a~ 40c：Operating portion；41a~41c：Display part；42：Notification unit；45：Control unit；50：Drive circuit；100：Induction heating cooking Device；231a、231b：IGBT；232a、232b：IGBT；233a、233b：IGBT；231c、231d：Diode；232c、232d：Two Pole pipe；233c、233d：Diode.

Specific embodiment

Implementation method 1.

(structure)

Fig. 1 is the exploded perspective view of the induction heating cooking instrument for showing implementation method 1.

As shown in figure 1, on the top of induction heating cooking instrument 100, with the top board 4 for placing the heating objects 5 such as pot.On top On plate 4, as the heating gate for carrying out sensing heating to heating object 5, possess the first heating gate 1, the second heating gate 2, Three heating gates 3, possess the first heating unit 11, the second heating unit 12, the 3rd heating unit 13 with each heating gate accordingly, Can place heating object 5 for each heating gate to carry out sensing heating.

In present embodiment 1, the first heating unit 11 and second is provided with front side left-right situs in main body and is added Hot cell 12, in the inner side approximate centre of main body, there is provided the 3rd heating unit 13.

In addition, the configuration not limited to this of each heating gate.For example, it is also possible to substantially linearly transversely arranged configuration 3 adds Hot mouth.Alternatively, it is also possible to be configured to the depth direction at the center of the first heating unit 11 and the center of the second heating unit 12 Position is different.

Top board 4 is overall to constitute the material of infrared transmitting by resistance to thermal reinforced glass or crystallization glass etc., with sense Answer between the upper surface open periphery of the main body of heating device 100 across rubber system filler or encapsulant, be fixed to not Permeable state.On the top plate 4, with the heating model of the first heating unit 11, the second heating unit 12 and the 3rd heating unit 13 Enclose (heating gate) accordingly, by coating or printing of coating etc., form the circle of the placement location substantially for representing pot Pot position display.

In top board 4 with front side, added with the first heating unit 11, the second heating unit 12 and the 3rd as setting The input dress of firepower and cooking menu (pattern of heating up water, fried pattern etc.) when hot cell 13 is heated to heating object 5 Put, there is provided operating portion 40a, operating portion 40b and operating portion 40c (being sometime collectively referred to as operating portion 40 below).In addition, in operation The vicinity in portion 40, as notification unit 42, there is provided showing the operating state of induction heating cooking instrument 100 and from operating portion Display part 41a, the display part 41b and display part 41c of 40 input/operation content etc..In addition, operating portion 40a~40c and aobvious Show that portion 41a~41c is not particularly limited in situation about being set for each heating gate or heating gate is set behaviour altogether Make situation of portion 40 and display part 41 etc..

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

In the inside of the main body of induction heating cooking instrument 100, there is provided to the first heating unit 11, the second heating unit 12 And the 3rd heating unit 13 heating coil supply high frequency electric power drive circuit 50 and for including the ground of drive circuit 50 The control unit 45 of the overall action of control induction heating cooking instrument.

Heating coil has the flat shape of circular, any by what is wound in a circumferential direction by insulating coating Metal (such as copper, aluminium etc.) constitute conductor wire and constitute, by using 50 pairs of each heating coil supply high frequencies of drive circuit Electric power, carries out sensing heating action.

Fig. 2 is the figure of the drive circuit of the induction heating cooking instrument for showing implementation method 1.In addition, drive circuit 50 is pin Each heating unit is set, but its circuit structure both can be with identical, it is also possible to changed for each heating unit.In figure In 2,1 drive circuit 50 is illustrate only.As shown in Fig. 2 drive circuit 50 possesses DC power supply circuit 22, inverter circuit 23 And resonating capacitor 24a.

Input electric cur- rent measure unit 25a detections are input to the electricity of DC power supply circuit 22 from AC power (source power supply) 21 Stream, by the voltage signal output suitable with input current value to control unit 45.

DC power supply circuit 22 possesses diode bridge 22a, reactor 22b, smoothing capacity device 22c, will be from AC power 21 The alternating voltage of input is transformed to DC voltage, output to inverter circuit 23.

Inverter circuit 23 is will to be connected with the output of DC power supply circuit 22 company as IGBT23a, 23b of switch element The inverter of the so-called semi-bridge type for having connect, as fly-wheel diode, be connected in parallel respectively with IGBT23a, 23b diode 23c, 23d.The direct current power exported from DC power supply circuit 22 is transformed to inverter circuit 23 high frequency of 20kHz~50kHz or so Alternating electromotive force, be supplied to the resonant circuit being made up of heating coil 11a and resonating capacitor 24a.Resonating capacitor 24a with plus Heat coil 11a is connected in series, and the resonant circuit turns into the electric capacity of the inductance of heating coil 11a and resonating capacitor 24a etc. Corresponding resonant frequency.In addition, the inductance of heating coil 11a in heating object 5 (metal load) magnetic coupling when according to metal The characteristic of load and change, the change according to the inductance and the variation of resonant frequency of resonant circuit.

By so composition, the high frequency electric of tens A or so is flowed through in heating coil 11a, by using what is flowed through The high frequency magnetic flux that high frequency electric is produced, the heating object 5 to be placed on the top board 4 of the surface of heating coil 11a is carried out Sensing heating.Constituted but it is also possible to be using with the semiconductor that is for example made up of silicon systems as IGBT23a, 23b of switch element The structure of the wide band gap semiconducter such as carborundum or gallium nitride material.

By using wide band gap semiconducter as switch element, the energization loss of switch element can be reduced, in addition, i.e. Make for switching frequency (driving frequency) to be set to high frequency (high speed), the radiating of drive circuit is also good, it is possible to by drive circuit Fin be set to small-sized, miniaturization and the cost degradation of drive circuit can be realized.

Coil current detection unit 25b is connected between heating coil 11a and resonating capacitor 24a.Coil current is detected The electric current that unit 25b detections are for example flowed through in heating coil 11a, the voltage signal suitable with heating coil current value is exported To control unit 45.

Temperature detecting unit 30 is for example made up of thermistor, is examined according to the heat delivered from heating object 5 to top board 4 Testing temperature.In addition, being not limited to thermistor, it is also possible to use the arbitrary sensor such as infrared ray sensor.

Fig. 3 is a functional block diagram for example of the control unit of the induction heating cooking instrument for showing implementation method 1.Reference picture 3, illustrate control unit 45.

Control unit 45 controls the induction heating cooking instrument 100 being made up of microcomputer or DSP (digital signal processor) etc. Action, possess drive control unit 31, load identifying unit 32, driving frequency setup unit 33, curent change detection unit 34, Period measuring unit 35, input and output control unit 36.

Drive control unit 31 is switched by IGBT23a, 23b output drive signal DS to inverter circuit 23 Action, drives inverter circuit 23.Also, the RF power that drive control unit 31 is supplied by control to heating coil 11a, Control the heating to heating object 5.Drive signal DS be by the conducting dutycycle (such as 0.5) of such as regulation 20~ The signal that the driving frequency of the regulation of 50kHz or so is constituted.

Load identifying unit 32 carries out the load determination processing of heating object 5, and the material of heating object 5 is judged as load Matter.In addition, the material for turning into the heating object 5 (pot) of load is substantially determined as such as iron, SUS430 by load identifying unit 32 Deng low resistance nonmagnetic substances such as the high resistance such as magnetic material, SUS304 nonmagnetic substance, aluminium, copper.

Driving frequency setup unit 33 is set to inverter electricity when being supplied from inverter circuit 23 to heating coil 11a The driving frequency f of the drive signal DS of the output of road 23.Particularly, driving frequency setup unit 33 has according to load identifying unit 32 result of determination is automatically set the function of driving frequency f.Specifically, in driving frequency setup unit 33, store Form for determining driving frequency f according to such as material of heating object 5 and setting firepower.Then, driving frequency setting is single Unit 33 determines the value fd of driving frequency f by referring to the form when load result of determination and setting firepower has been transfused to. In addition, driving frequency setup unit 33 sets the resonant frequency than resonant circuit to make the constant mode too much of input current Frequency higher.

So, by driving frequency setup unit 33 according to load result of determination, according to corresponding with the material of heating object 5 Driving frequency f drive inverter circuit 23, the increase of input current can be suppressed, it is possible to suppressing inverter circuit 23 High temperature improves reliability.

Curent change detection unit 34 is driven when according to the driving frequency f=fd set in driving frequency setup unit 33 When having moved inverter circuit 23, the time variation amount Δ I of input current of the detection per the stipulated time.In addition, the stipulated time both may be used Being during having preset, or during being changed by the operation of operating portion 40.

Period measuring unit 35 is measured from beginning to heating coil 11a supply electric powers in curent change detection unit 34 Time variation amount Δ I is changed into the heat time t1 below setting value.In addition, period measuring unit 35 measures the phase of heat time t1 Between in, the current change quantity I1 of input current.

In addition, heat time t1 equivalent to the present invention in " very first time ".

Drive control unit 31 according to the heat time t1 and current change quantity I1 measured by period measuring unit 35, Make the electric power reduction to heating coil 11a supplies.Drive control unit 31 releases the fixation of driving frequency f=fd, makes driving frequently Rate f increases increment Delta f, and (f=fd+ Δ f) drive inverter circuit 23.Particularly, in drive control unit 31, the heat time T1 is shorter, and current change quantity I1 is smaller, then be set to increment Delta f bigger.

(action)

Next, the action example of the induction heating cooking instrument 100 of explanation implementation method 1.

First, illustrate according to the firepower set by operating portion 40 to being heated for being placed on the heating gate of top board 4 Thing 5 carries out the action in the case of sensing heating.

When placing heating object 5 on heating gate by user and (firepower access) carrying out heating to operating portion 40 During instruction, the load identifying unit 32 of control unit 45 carries out load determination processing.

Fig. 4 is to show that input current in the drive circuit of Fig. 3, for driving frequency becomes according to the temperature of heating object The figure of the situation changed and change.

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

As shown in figure 4, according to the material of the pot load that placed on the top plate 4, the relation of coil current and input current It is different.Control unit 45 internally stores carried out tabular to the coil current and the relation of input current shown in Fig. 4 in advance Load judge form.Judge form by internally storing load, load identifying unit 32 can be constituted with cheap structure.

In load determination processing, the specific drive signal of load judgement of control unit 45 drives inverter circuit 23, according to the output signal of input electric cur- rent measure unit 25a, detect input current.In addition, simultaneously, control unit 45 is according to coil The output signal of current detecting unit 25b, detection coil electric current.Control unit 45 is according to the coil current and input electricity for detecting The load for flowing and illustrating the relation of Fig. 4 judges form, judges the material of be placed heating object (pot) 5.So, control Put above heating coil 11a according to input current and the correlation of coil current, judgement in portion 45 (load identifying unit 32) The material of the heating object 5 put.

After load determination processing more than having carried out, control unit 45 carries out the control based on load result of determination and moves Make.

In the case where load result of determination is low resistance nonmagnetic substance, in the induction heating cooking of present embodiment 1 Can not be heated in device 100, so notifying notification unit 42 to heat, urge user's change pot.Now, it is not electric from driving Road 50 is to heating coil 11a supply high frequency electric power.

Even if in addition, being in the case of uncharging, notification unit 42 to be notified to heat in load result of determination, urging User places pot.Now, similarly not to heating coil 11a supply high frequency electric power.

In the case where load result of determination is magnetic material or high resistance nonmagnetic substance, due to these pots be can The material heated by the induction heating cooking instrument 100 of present embodiment 1, so control unit 45 is determined and the pot material that determined The corresponding driving frequency of matter.On the driving frequency, the frequency higher than resonant frequency is set to, to avoid input current excessive. The driving frequency can be determined by referring to form of frequency for example corresponding with the material and setting firepower of heating object 5 etc.. Control unit 45 fixes the determined driving frequency of institute, drives inverter circuit 23, starts sensing heating action.

Fig. 5 is to show that input current in the drive circuit of Fig. 3, for driving frequency becomes according to the temperature of heating object The figure of the situation changed and change.In Figure 5, fine rule is characteristic when heating object 5 (pot) is low temperature, and thick line is heating object 5 be high temperature when characteristic.

As shown in figure 5, temperature according to heating object 5 and be to be added because temperature rises the reason for characteristic variations The resistivity of hot thing 5 increases, and permeability reduction, so that the magnetic coupling change of heating coil 11a and heating object 5.

In the control unit 45 of the induction heating cooking instrument 100 of present embodiment 1, will be than the input current shown in Fig. 5 Maximum frequency frequency higher is determined as driving frequency, fixes the driving frequency to control inverter circuit 23.

Fig. 6 is the figure of the part shown in the dotted line being exaggerated in the figure of Fig. 5.

If fixing driving frequency corresponding with the pot material that be determined in above-mentioned load determination processing to control inversion Device circuit 23, then as heating object 5 becomes high temperature from low temperature, input current value (operating point) under the driving frequency is from point A Change turns to point B, and the temperature with heating object 5 rises, and input current is gradually reduced.

Now, control unit 45 obtains the every of input current in the state of the driving frequency for securing inverter circuit 23 The variable quantity (time variation amount Δ I) of hour, according to time variation amount Δ I, detects the temperature change of heating object 5.

Therefore, the material of heating object 5 is not relied on, the temperature change of heating object 5 can be detected.In addition, being capable of root According to the change of input current, the temperature change of heating object 5 is detected, it is possible to detecting quilt more at high speed than temperature sensor etc. Heat the temperature change of thing 5.

In addition, the material of the heating object 5 that judgement placed above heating coil 11a, according to the material of heating object 5 Matter, determines the driving frequency of inverter circuit 23, and inverter circuit 23 is driven according to the driving frequency.Therefore, it is possible to basis with The corresponding driving frequency of material of heating object 5, regularly drives inverter circuit 23, can suppress the increase of input current. Therefore, it is possible to suppress the high temperature of inverter circuit 23, it is possible to increase reliability.

(pattern 1 of heating up water)

Next, explanation have selected the action of heating up water of the water for carrying out being put into heating object 5 by operating portion 40 The pattern of heating up water is used as the action in the case of cooking menu (pattern).

Control unit 45 carries out load determination processing in the same manner as above-mentioned action, determines corresponding with the pot material that determined Driving frequency, the fixed determined driving frequency of institute drives inverter circuit 23 to implement sensing heating action.Then, control Portion 45 judges that boiling is completed according to the time variation amount Δ I of input current.Herein, by Fig. 7, illustrate into water-filling when heating up water Elapsed time and each characteristic change.

The figure that the time of temperature, input current when Fig. 7 shows to be driven according to the driving frequency of the regulation of Fig. 3 passes through Shape.

In fig. 7 it is shown that elapsed time when being put into water and acted with the pattern of heating up water in the heating object 5 and The change of each characteristic, Fig. 7 (a) shows that driving frequency, Fig. 7 (b) show that temperature (water temperature), Fig. 7 (c) show input current.

As shown in Fig. 7 (a), if fixed drive frequency carries out the control of inverter circuit 23, as shown in Fig. 7 (b), The temperature (water temperature) of heating object 5 gradually rises up to boiling, if boiling, it is for about 100 DEG C that temperature is constant.Now, such as Fig. 7 C shown in (), correspondingly, input current is gradually reduced the rising with the temperature of heating object 5, if boiling water and temperature turns into perseverance Fixed, then input current also turns into constant.That is, if input current turns into constant, boiling water and completion of heating up water.

Thus, the control unit 45 in present embodiment 1 is asked in the state of the driving frequency for securing inverter circuit 23 Go out the variable quantity hourly (time variation amount Δ I) of input current, in the situation that time variation amount Δ I is below setting value Under, it is judged as completion of heating up water.

In addition, the information of setting value can both set in control unit 45 in advance, it is also possible to can be defeated from operating portion 40 etc. Enter.

Then, control unit 45 is notified to heat up water the meaning for completing using notification unit 42.Herein, as notification unit 42, the display of boiling completion etc. is carried out in display part 41 or using loudspeaker (not shown) with sound notification user, its Mode is not particularly limited.

As described above, in the pattern of heating up water of the action of heating up water of setting water, the driving of inverter circuit 23 is being secured In the state of frequency, the time variation amount Δ I of input current is obtained, when time variation amount Δ I is below setting value, passed through Notification unit 42 notifies the meaning that completes of heating up water.

Therefore, it is possible to promptly notify the completion of heating up water of water, the good induction heating cooking instrument of convenience can be obtained.

In addition, control unit 45 is when the time variation amount Δ I of input current is sought, it is not necessary to high-precision microcomputer, so energy Access the induction heating cooking instrument of the detection that can carry out heating up water in inexpensive manner.

(pattern 2 of heating up water)

Next, explanation have selected other control actions in the case of the pattern of heating up water by operating portion 40.

Control unit 45 carries out load determination processing in the same manner as above-mentioned action, determines corresponding with the pot material that determined Driving frequency, the fixed determined driving frequency of institute drives inverter circuit 23 to implement sensing heating action.Then, control Portion 45 judges that boiling is completed according to the time variation amount Δ I of input current.

And then, the time variation amount Δ that control unit 45 is obtained in the state of the driving frequency for securing inverter circuit 23 I be setting value below in the case of, release driving frequency fixation.Then, control unit 45 is according to until time variation amount Δ I is The current change quantity 11 of the input current in during the heat time t1 and heat time t1 untill below setting value, makes inversion The driving frequency of device circuit 23 is variable, makes the RF power to heating coil 11a supplies variable.By Fig. 8~Figure 11, this is illustrated The details of the action of sample.

Fig. 8 shows driving frequency, temperature, the input current in the pattern 2 of heating up water of the induction heating cooking instrument of implementation method 1 With the figure of the relation of time.

In fig. 8 it is shown that the change in the elapsed time and each characteristic when being put into water in heating object 5 and being heated up water Change.

Fig. 8 (a)~(c) is the characteristic when the initial temperature of the interior water being put into of heating object 5 is high, and Fig. 8 (a) shows to drive Dynamic frequency, Fig. 8 (b) show that temperature (water temperature), Fig. 8 (c) show input current.

Fig. 8 (d)~(f) is the characteristic when the initial temperature of the interior water being put into of heating object 5 is low, and Fig. 8 (d) shows to drive Dynamic frequency, Fig. 8 (e) show that temperature (water temperature), Fig. 8 (f) show input current.

Fig. 9 is the figure of the part shown in the dotted line for being exaggerated Fig. 5.

Herein, initial temperature refers to the temperature from the scope during regulation is begun heat to, and is not limited to heating and starts When.

In addition, in fig. 8, be set to initial temperature situation high and it is low in the case of water (content) amount it is substantially equivalent To illustrate.That is, the thermic load of the content of the heating object 5 in the heating starting stage is true by the temperature and amount of content Fixed, but if the amount of content is equal to, then thermic load depends on initial temperature.

Figure 10 is the flow chart of the action example of the pattern 2 of heating up water of the induction heating cooking instrument for showing implementation method 1.

Figure 11 is the flow chart of the action example of the initial water temperature detection for showing Figure 11.

Hereinafter, according to the flow chart of Figure 10, Figure 11, reference picture 8, Fig. 9 is illustrated.

First, heating object 5 is placed on the heating gate of top board 4 by user, heating is carried out to operating portion 40 and starts (fire Power access) instruction.Then, in load identifying unit 32, the load of the relation for representing input current and coil current is used Judge form, the material (step ST1) of the heating object (pot) 5 for judging placed as load.In addition, being judged to that load sentences It is the material that can not heat or in the case of uncharging to determine result, and the meaning is notified from notification unit 42, is controlled into not from drive Dynamic circuit 50 is to heating coil 11a supply high frequency electric power.

Next, in driving frequency setup unit 33, determining and the load result of determination according to load identifying unit 32 Value fd (step ST2) of the corresponding driving frequency f of pot material that determined.Now, driving frequency f is set as comparing resonant circuit Resonant frequency frequency f=fd higher, to avoid input current from becoming too much.

Afterwards, driving frequency f is fixed as into fd by using drive control unit 31 drives inverter circuit 23, starts Sensing heating acts (step ST3).Together with beginning with the sensing heating action caused by power supply, start by period Measuring unit 35 measures heat time t1 and current change quantity I1.

If fixed drive frequency and begin to warm up (Fig. 8 (a), (d)), the temperature (water temperature) of heating object 5 gradually goes up Rise to boiling (Fig. 8 (b), (e)).In the control for fixing the driving frequency, as shown in figure 9, the input electricity under the driving frequency Flow valuve (operating point) turns to point B from point A changes, and the temperature with heating object 5 rises, and input current is gradually reduced.

During sensing heating action is carried out, according to the sampling interval of regulation in curent change detection unit 34, meter Evaluation time variation delta I (step ST4).

Then, judge time variation amount Δ I whether be setting value (Iref) below (step ST5).With heating object 5 from Low temperature becomes high temperature, and time variation amount Δ I diminishes (Fig. 8 (c), (f)).If boiling water and temperature turn into constant, input electricity Stream also turns into constant (Fig. 8 (c), (f)).Thus, in heat time t1, control unit 45 is judged to the time change of input current Amount Δ I be setting value (Iref) below.

Then, when time variation amount Δ I is below setting value, heat time t1 is detected in period measuring unit 35 (step ST6).In addition, in period measuring unit 35, detection is since the heating to the input current during heat time t1 Current change quantity I1 (step ST7).

Afterwards, drive control unit 31 implements the treatment of initial water temperature detection, according to heat time t1 and current change quantity I1, determines increment Delta f (step ST8) of driving frequency f.

During heat time t1, fixed drive frequency and be driven, so according to being put into heating object 5 The initial temperature of water, heat time t1 and current change quantity I1 change.That is, in the case of initial temperature (T0) height of water (Fig. 8 (b)), the heat time, t1 shortened, and current change quantity I1 diminishes.On the other hand, (the figure in the case where the initial temperature of water is low 8 (e)), the heat time, t1 was elongated, and current change quantity I1 becomes big.

Thereby, it is possible to according to heat time t1 and current change quantity I1, judge that the initial temperature of water (heats the starting stage Thermic load).

By Figure 11, the details of the treatment of the initial water temperature detection is illustrated.

Control unit 45 judge heat time t1 whether than specify reference time t_ref1 is shorter and current change quantity I1 It is whether smaller (step ST81) than the reference current change quantity I_ref1 for specifying.

In the case where the condition of step ST81 is met, control unit 45 is judged to that the initial temperature of water is (heat-flash startup) high (step ST82).If such as water amount, it is known that if can be speculated as the initial temperature (T0) of water be more than T_ref1.

On the other hand, in the case where the condition of step ST81 is unsatisfactory for, control unit 45 judge heat time t1 whether as Below the reference time t_ref2 of regulation, and whether current change quantity I1 is below the reference current change quantity I_ref2 for specifying (step ST83).Herein, reference time t_ref2 is the time longer than reference time t_ref1.With reference to current change quantity I_ Ref2 is than with reference to current change quantity I_ref1 bigger value.

In the case where the condition of step ST83 is met, control unit 45 is judged to that the initial temperature of water starts than above-mentioned heat-flash Lower (weak thermal starting) (step ST84).If such as water amount, it is known that if can be speculated as the initial temperature (T0) of water be T_ More than ref2 and less than T_ref1.

On the other hand, in the case where the condition of step ST83 is unsatisfactory for, control unit 45 is judged to the initial temperature ratio of water Above-mentioned weak thermal starting is lower (generally heating) (step ST85).If such as water amount, it is known that if can be speculated as the initial of water Temperature (T0) is less than T_ref2.

Figure 12 is to show reference time and with reference to current change quantity and the figure of the relation of the thermic load of heating starting stage.

As shown in figure 12, the treatment for being judged by the initial water temperature of step ST81~ST85, according to heat time t1 and Current change quantity I1, in control unit 45, heat time t1 is shorter, current change quantity I1 is smaller, then be speculated as heating initial rank The thermic load of the content of the heating object 5 in section is smaller (temperature of water is higher).

In addition, herein, illustrate reference time and be respectively the situation of 2 with reference to current change quantity, but it is also possible to set The reference time of fixed more than 3 and judge with reference to current change quantity.

Herein, heat time t1 and current change quantity I1 change not only according to initial temperature, always according to the amount of water, institute To need the amount according to water, each reference time and each ginseng in the treatment of the initial water temperature judgement of setting procedure ST81~ST85 According to current change quantity.Accordingly it is also possible to for example, by advance by each reference time corresponding with the amount of water (amount of content) with And each information Store with reference to current change quantity is form, the information for obtaining the amount (amount of content) of water determines each reference Time and each reference current change quantity.Thereby, it is possible to more precisely detect the initial temperature (thermic load) of water.In addition, water The information of amount can be both input into from the grade of operating portion 40, it is also possible to for example, by gravity sensor etc. according to heating object 5 Weight judge water amount.In addition, the amount of water need not obtain rigorous value, or for example less, in, many this 3 stages etc..

Next, the drive control unit 31 of control unit 45 makes inverter circuit 23 by releasing the fixation of driving frequency Driving frequency increase and reduce input current, make RF power (firepower) reduction to heating coil 11a supplies.That is, exist During the insulation of heating object 5, it is not necessary to make temperature rise degree firepower, so suppress from heating coil 11a to be heated The heating amount of thing 5.

Now, the initial temperature (thermic load) that the drive control unit 31 of control unit 45 is arrived by inference, control is to heating The RF power of coil 11a supplies.In drive control unit 31, f is changed to from the driving frequency f=fd of inverter circuit 23 =fd+ Δ f, the RF power for reducing is fed into heating coil 11a (steps ST86, Fig. 8 (a) from inverter circuit 23 (d))。

Herein, increment (the Δ f) of driving frequency is illustrated.

In the case where the situation that heat time t1 is short and current change quantity I1 is small, i.e. heat-flash starts, such as shown in Fig. 8 (a), Drive control unit 31 is significantly increased driving frequency f, and inversion is driven by the drive signal DS of driving frequency f=fd+ Δs f1 Device circuit 23.

On the other hand, in the case of the situation that heat time t1 is long and current change quantity I1 is big, i.e. weak thermal starting, such as scheme Shown in 8 (d), drive control unit 31 makes driving frequency f slightly increase, by the drive signal DS of driving frequency f=fd+ Δs f2 Drive inverter circuit 23.

In addition, in the situation that heat time t1 is longer and current change quantity I1 is bigger, i.e. generally heating in the case of, drive Control unit 31 makes driving frequency f more slightly increase than Δ f2 and drive inverter circuit 23.

In addition, increment Delta f1, the information of Δ f2 on driving frequency, can both be pre-set in control unit 45, also may be used Can be input into from the grade of operating portion 40.

Even if as shown in figure 9, reducing firepower with improve improve frequency f, water temperature is also hardly reduced and persistently keeps permanent The mode of fixed temperature, setting increment Delta f1, Δ f2, operating point turns to point C1 (or point C2) from point B changes.Then, even if carrying Driving frequency f high reduces firepower, and water temperature also hardly reduces and maintain keeping warm mode.

So, on the RF power (firepower) accessed after heat time t1, in the thermic load of heating starting stage In the case of small (initial temperature is high), firepower is set to it is relatively low, it is big (initial temperature is low) in the thermic load of heating starting stage In the case of, firepower is set to higher.

Accordingly, it is capable to access the energy-conservation and convenience that insulation action can be carried out while unhelpful power supply is suppressed Good induction heating cooking instrument.

Particularly, in the case of (boiling of water) pattern of heating up water, even if unnecessarily improving firepower, water temperature also will not be into It it is more than 100 DEG C, even if so improve improve frequency f reduces firepower, it is also possible to maintain fluidized state.

So, in the case where the time variation amount Δ I of input current is for below setting value, control inverter circuit 23 Drive, reduce the RF power to heating coil 11a supplies, it is possible to suppressing input electric power to realize energy-saving.

I.e., as in the past, in the case of the driving frequency f of regulation is only increased to when as setting value, existing cannot Thermic load (temperature and amount) according to content keep optimal keeping warm mode as problem.For example, in heating object 5 In the case that the initial temperature of content is low, shortage of heat and temperature is gradually reduced, it is necessary to reheat.On the other hand, added In the case that the initial temperature of the content of hot thing 5 is high, superfluous electric power is consumed.

In present embodiment 1, if the thermic load (temperature and amount) for being conceived to the content of heating object 5 is different, Even if then driving frequency f identical (firepower is identical), heat time t1 and current change quantity I1 also different this point, drive control Unit 31 determines increment Delta f according to heat time t1 and current change quantity 11, changes driving frequency f during insulation.Thus, Can be according to the thermic load of heating object 5, to the enough electric power needed for heating coil 11a supplies, it is possible to efficiently real Existing energy-saving.

Referring again to Figure 10.After step ST8, drive control unit 31 from time variation amount Δ I be setting value with (t2=t1+ Δ t) carry out having heated up water by notification unit 42 to user after the lower additional period Δ t that have passed through regulation Into notice (step ST9).

In addition, control unit 45 is more shorter than reference time t_ref1 (time reference value) in heat time t1 and electric current becomes Change amount I1 ratios with reference to current change quantity I_ref1 (current reference value) it is smaller in the case of (heat-flash startup), it is also possible to when anaplasia When change amount Δ I is below setting value, notify to heat up water the meaning for completing by notification unit 42.

(pattern 3 of heating up water)

Next, explanation have selected other control actions in the case of the pattern of heating up water by operating portion 40.

Control unit 45 carries out load determination processing in the same manner as above-mentioned action, determines corresponding with the pot material that determined Driving frequency, the fixed determined driving frequency of institute drives inverter circuit 23 to implement sensing heating action.Then, control Portion 45 judges that boiling is completed according to the time variation amount Δ I of input current.

And then, the time variation amount Δ that control unit 45 is obtained in the state of the driving frequency for securing inverter circuit 23 I be setting value below after, continue the stipulated time ground carry out identical control, after by the stipulated time, release drive frequently The fixation of rate, makes the driving frequency of inverter circuit 23 variable, makes the RF power to heating coil 11a supplies variable.Pass through Fig. 9 and Figure 13, illustrates the details of such action.

Figure 13 is driving frequency, temperature, the input in the pattern 3 of heating up water of the induction heating cooking instrument for showing implementation method 1 The figure of the relation of electric current and time.

In fig. 13 it is shown that the change in the elapsed time and each characteristic when being put into water and heated up water in heating object 5 Change.

Figure 13 (a)~(c) is the characteristic when the initial temperature of the interior water being put into of heating object 5 is high, and Figure 13 (a) shows Driving frequency, Figure 13 (b) show that temperature (water temperature), Figure 13 (c) show input current.

Figure 13 (d)~(f) is the characteristic when the initial temperature of the interior water being put into of heating object 5 is low, and Figure 13 (d) shows Driving frequency, Figure 13 (e) show that temperature (water temperature), Figure 13 (f) show input current.

In addition, in fig. 13, be set to initial temperature situation high and it is low in the case of water (content) amount substantially etc. Illustrate together.That is, the thermic load of the content of the heating object 5 in the heating starting stage is true by the temperature and amount of content Fixed, but if the amount of content is equal to, then thermic load depends on initial temperature.

In the same manner as action with above-mentioned pattern 1 of heating up water, if fixed drive frequency and begin to warm up (Figure 13 (a), (d)), Then the temperature (water temperature) of heating object 5 gradually rises up to seethe with excitement (Figure 13 (b), (e)).In the control for fixing the driving frequency, As shown in figure 9, the input current value (operating point) under the driving frequency becomes from point A turns to point B, with the temperature of heating object 5 Rise, input current is gradually reduced.

As described above, rising with the temperature of heating object 5, be the reason for input current is gradually reduced, by due to Temperature rises and the resistivity of heating object 5, permeability change, the magnetic coupling change of heating coil 11a and heating object 5.That is, Input current turn into constant state mean the temperature of heating object 5 (position particularly close with heating coil 11a) into For constant.

During input current turns into constant heat time t1 in Figure 13 (c), (f), the temperature of heating object 5 reaches about 100 DEG C, but there is temperature inequality in the water that the inside of heating object 5 has been put into, as whole water, not up to seethe with excitement sometimes.

In this heats up water pattern 3, it is driven with the state for securing driving frequency, until to heat time t1 plus attached Between the added-time untill heat time t2 obtained from Δ t such that it is able to make whole boiling waters reliably in a short time.In heating In time t2, control unit 45 is judged as completion of heating up water.

In addition, additional period Δ t equivalent to the present invention in " the second time ".

Herein, heat time t2 and additional period Δ t is illustrated.

Additional period Δ t is the difference of heat time t2 and heat time t1, is represented with Δ t=t2-t1.In the pattern of heating up water In 3, by control unit 45, determine turns into constant heat time t1 since heating to input current, according to heat time t1 Length and the current change quantity I1 untill heat time t1 size, make additional period Δ t change.

In the heating starting stage of the pattern of heating up water 3, fixed drive frequency drives, so by heating object 5 The thermic load (initial temperature and amount) of the water being put into, heat time t1 and current change quantity I1 change.That is, in the first of water In the case that beginning temperature is high (Figure 13 (b)), the heat time, t1 shortened, and current change quantity I1 diminishes.In addition, in the initial temperature of water In the case of low (Figure 13 (e)), the heat time, t1 was elongated, and current change quantity I1 becomes big.Heat time t1 is short and curent change In the case that amount I1 is small, such as shown in Figure 13 (c), be set to for additional period Δ t shorter by control unit 45.On the other hand, in heating Time t1 is long and in the case that I1 is big, and as shown in Figure 13 (f), be set to for additional period Δ t more long by control unit 45.

In the case where the initial temperature of water is low, compared to situation high, the temperature of the water of the inside of heating object 5 is uneven The situation for becoming big is more, in order that the water of whole reliably seethes with excitement, it is necessary to more times.

Accordingly, it is capable to access following energy-conservation and the good induction heating cooking instrument of convenience, the induction heating cooking Device detects the water of the inside of heating object 5 in the pattern of heating up water 3 by measuring heat time t1 and current change quantity I1 Initial temperature, by setting additional period Δ t corresponding with the initial temperature of water, the unhelpful electric power needed for boiling can be suppressed Supply, and make whole boiling waters reliably in a short time.

Next, control unit 45 is after from heat time t1 by additional period Δ t, the fixation of driving frequency is released, Making the driving frequency of inverter circuit 23 increases, so that input current reduction, makes the RF power to heating coil 11a supplies (firepower) is reduced.Make the increased control of driving frequency identical with above-mentioned pattern 2 of heating up water.Even if improve improve frequency and firepower drops Low, water temperature is also hardly reduced, so as shown in figure 9, it is point C1 (point C2) that operating point moves (change) from point B.

In addition, in heat time t2, control unit 45 improves the driving frequency of inverter circuit 23, and by advice note Unit 42, the notice of the completion that to user heat up water.In addition, both can be that driving frequency is being improved into it to the notice of user Before can also be improve after.

In addition, in the above description, describe changing driving frequency come by way of controlling RF power (firepower), but Firepower can also be controlled using the conducting dutycycle (ON-OFF ratio) of the switch element by changing inverter circuit 23 Mode.

In addition, by the way that effectively using the temperature information detected by temperature detecting unit 30, reliability can be obtained higher Induction heating cooking instrument.

(configuration examples of other drive circuits)

Next, illustrating the example of other drive circuits.

Figure 14 is the figure of other drive circuits of the induction heating cooking instrument for showing implementation method 1.

Drive circuit 50 shown in Figure 14 is the structure that resonating capacitor 24b is addition of to the structure shown in Fig. 2.In addition, Other structures are identical with Fig. 2, to a part of additional same symbol.

As described above, resonant circuit is constituted by heating coil 11a and resonating capacitor, so being cooked according to for sensing heating The necessary maximum fire of device (maximum input electric power) is adjusted, the electric capacity of resonating capacitor is determined.In the drive circuit 50 shown in Figure 10 In, it is connected in parallel by by resonating capacitor 24a and 24b, can halve respective electric capacity, even if using 2 resonance In the case of capacitor, it is also possible to obtain cheap control circuit.

In addition, configure coil current by the resonating capacitor 24a sides in the resonating capacitor being connected in parallel detecting Unit 25b, the electric current flowed through in coil current detection unit 25b turns into the half of the electric current flowed through in heating coil 11a, It is possible to using small-sized and small capacitances coil current detection unit 25b, small-sized and cheap control circuit, energy can be obtained Access cheap induction heating cooking instrument.

In addition, in present embodiment 1, illustrating the input current that detection is detected by input electric cur- rent measure unit 25a Time variation amount example, but can both replace input current, the coil that is detected by coil current detection unit 25b of detection The time variation amount Δ I of electric current, it is also possible to detect input current and the time variation amount Δ I both coil current.

In addition, in present embodiment 1, illustrate the inverter circuit 23 of semi-bridge type but it is also possible to be using bridge-type Or the structure of the inverter of monoblock type (one-piece) series resonance type etc..

And then, illustrate to use in the load determination processing in load identifying unit 32 coil current and primary current The mode of relation, but it is also possible to carry out load determination processing using the resonance voltage at the two ends by detecting resonating capacitor Mode, the mode that load judges is not particularly limited.

In addition, describing the implementation method more than, judgement is put into the feelings of the initial temperature of the water of heating object Condition, but it is also possible to for each result of determination given threshold etc. of load identifying unit 32, according to sentencing for load identifying unit 32 Determine result, thus it is speculated that be put into the initial temperature of the water of heating object.

Implementation method 2.

In present embodiment 2, the details of the drive circuit 50 in above-mentioned implementation method 1 is illustrated.

Figure 15 is the figure of a part for the drive circuit of the induction heating cooking instrument for showing implementation method 2.In addition, in Figure 15 In, illustrate only the structure of a part for the drive circuit 50 of above-mentioned implementation method 1.

As shown in figure 15, inverter circuit 23 possesses 2 switch elements by being connected in series between positive and negative busbar (IGBT23a, 23b) and the 1 group of branch road constituted with the switch element inverse parallel is connected to respectively diode 23c, 23d.

IGBT23a and IGBT23b is switched on cut-off and is driven by the drive signal exported from control unit 45.

IGBT23b is set to cut-off state by control unit 45 during IGBT23a is turned on, and makes what IGBT23a ended Period, IGBT23b is set to conducting state, output is alternately turned on the drive signal of cut-off.

Thus, by IGBT23a and IGBT23b, the half-bridge inverter for driving heating coil 11a is constituted.

In addition, by IGBT23a and IGBT23b, constituting " the half-bridge inverter circuit " in the present invention.

Control unit 45 is input into the drive signal of high frequency to IGBT23a and IGBT23b according to electric power (firepower) is accessed, and adjusts Whole heating output.The drive signal exported to IGBT23a and IGBT23b is than by heating coil 11a and resonating capacitor Variable in the range of the resonant frequency driving frequency higher of the load circuit that 24a is constituted, control is flowed through in being formed in load circuit Electric current flowed through with the phase more late than the voltage applied to load circuit.

Next, illustrating the control using the driving frequency of inverter circuit 23 and the access electric power (firepower) of conducting dutycycle Braking is made.

Figure 16 is a figure for example of the drive signal of the half-bridge circuit for showing implementation method 2.Figure 16 (a) is firepower high The example of the drive signal of each switch under state.Figure 16 (b) is the example of the drive signal of each switch under low firepower state.

IGBT23a from control unit 45 to inverter circuit 23 and IGBT23b output than load circuit resonant frequency more The drive signal of high frequency high.

Increased and decreased by making the output of the changeable frequency of the drive signal, inverter circuit 23.

If for example, as shown in Figure 16 (a), reduce driving frequency, then to the high frequency electric of heating coil 11a supplies Frequency increases close to the resonant frequency of load circuit to the access electric power of heating coil 11a.

In addition, if as shown in Figure 16 (b), driving frequency is increased, then the high frequency electric for being supplied to heating coil 11a Frequency is reduced away from the resonant frequency of load circuit to the access electric power of heating coil 11a.

And then, control unit 45 can also by together with the control of the variable access electric power based on above-mentioned driving frequency, Make the conducting dutycycle of the IGBT23a and IGBT23b of inverter circuit 23 variable, control the output voltage of inverter circuit 23 Application time, control the access electric power to heating coil 11a.

In the case of making firepower increased, increase the ON time of the IGBT23a in 1 cycle of drive signal The ratio (conducting dutycycle) of (deadline of IGBT23b), increases the voltage application time width in 1 cycle.

In addition, in the case where firepower reduction is made, reducing the ON time of the IGBT23a in 1 cycle of drive signal The ratio (conducting dutycycle) of (deadline of IGBT23b), reduces the voltage application time width in 1 cycle.

In the example of Figure 16 (a), it is illustrated that the ON time T11a of the IGBT23a in 1 cycle T 11 of drive signal The ratio identical situation of the deadline T11b (ON time of IGBT23b) of (deadline of IGBT23b) and IGBT23a (conducting dutycycle is 50%).

In addition, in the example of Figure 16 (b), it is illustrated that during the conducting of the IGBT23a in 1 cycle T 12 of drive signal Between T12a (deadline of IGBT23b) it is identical with the ratio of the deadline T12b of IGBT23a (ON time of IGBT23b) Situation (conducting dutycycle is 50%).

Control unit 45 is when the often regulation of the input current illustrated in above-mentioned implementation method 1 (or coil current) is sought Between time variation amount Δ I when, in the state of the driving frequency for securing inverter circuit 23, by inverter circuit 23 The conducting dutycycle of IGBT23a and IGBT23b is set to fixed state.

Thereby, it is possible in the state of being constant to the access electric power of heating coil 11a, obtain input current (or line Loop current) per stipulated time time variation amount Δ I.

Implementation method 3.

In present embodiment 3, illustrate to use the inverter circuit 23 of full-bridge circuit.

Figure 17 is the figure of a part for the drive circuit of the induction heating cooking instrument for showing implementation method 3.In addition, in Figure 17 In, illustrate only the difference with the drive circuit 50 of above-mentioned implementation method 1.

In present embodiment 3,2 heating coils are provided with for 1 heating gate.2 heating coil such as diameters point It is not different, the configuration of concentric circles ground.Herein, the small heating coil of diameter is referred to as interior loop 11b, by the big heating coil of diameter Referred to as exterior loop 11c.

In addition, the quantity of heating coil and configuration not limited to this.For example, it is also possible to be configured to be configured at heating gate Multiple heating coils are configured around the heating coil in center.

Inverter circuit 23 possesses 2 switch elements (IGBT) by being connected in series between positive and negative busbar and is opened with this Close 3 groups of branch roads that the element diode that inverse parallel is connected to respectively is constituted.In addition, after which, 1 group in 3 groups of branch roads is claimed It is common branch, interior loop branch road and exterior loop branch road is referred to as by other 2 groups.

Common branch is the branch road being connected to interior loop 11b and exterior loop 11c, by IGBT232a, IGBT232b, two Pole pipe 232c and diode 232d is constituted.

Interior loop branch road is the branch road for being connected to interior loop 11b, by IGBT231a, IGBT231b, diode 231c with And diode 231d is constituted.

Exterior loop branch road is the branch road for being connected to exterior loop 11c, by IGBT233a, IGBT233b, diode 233c with And diode 233d is constituted.

The IGBT232a and IGBT232b of common branch, the IGBT231a and IGBT231b of interior loop branch road, exterior loop It is switched on cut-off and is driven by the drive signal exported from control unit 45 with the IGBT233a and IGBT233b of branch road.

IGBT232b is set to cut-off state by control unit 45 during the IGBT232a conductings of common branch are made, and is made IGBT232b is set to conducting state by IGBT232a during ending, and output is alternately carried out the drive signal of ON-OFF.

Similarly, control unit 45 is exported makes the IGBT231a and IGBT231b of interior loop branch road, exterior loop branch road IGBT233a and IGBT233b are alternately carried out the drive signal of ON-OFF.

Thus, the full-bridge inverter for driving interior loop 11b is made up of common branch and interior loop branch road.In addition, by public affairs Branch road and exterior loop constitute the full-bridge inverter for driving exterior loop 11c with branch road altogether.

In addition, constituting " full-bridge inverter circuit " in the present invention by common branch and interior loop branch road.In addition, by public affairs Branch road and exterior loop constitute " full-bridge inverter circuit " in the present invention with branch road altogether.

The load circuit being made up of interior loop 11b and resonating capacitor 24c is connected to the output point of common branch Output point (the connection of IGBT231a and IGBT231b of (tie point of IGBT232a and IGBT232b) and interior loop branch road Point) between.

The load circuit being made up of exterior loop 11c and resonating capacitor 24d be connected to the output point of common branch with it is outer Between the output point (tie point of IGBT233a and IGBT233b) of coil branch road.

Interior loop 11b is the small heating coil of the profile wound according to circular, and exterior loop is configured with its periphery 11c。

The coil current flowed through in interior loop 11b by coil current detection unit 25c, detection.Coil current is detected The peak value of the electric current that unit 25c detections are for example flowed through in interior loop 11b, by the voltage suitable with the peak value of heating coil current Signal output is to control unit 45.

The coil current flowed through in exterior loop 11c by coil current detection unit 25d, detection.Coil current is detected The peak value of the electric current that unit 25d detections are for example flowed through in exterior loop 11c, by the voltage suitable with the peak value of heating coil current Signal output is to control unit 45.

Control unit 45 according to electric power (firepower) is accessed, believe by the driving for exporting high frequency to the switch element (IGBT) of each branch road Number, adjustment heating output.

The drive signal exported to the switch element of common branch and interior loop branch road than by interior loop 11b and Variable in the range of the resonant frequency driving frequency higher of the load circuit that resonating capacitor 24c is constituted, control is formed in load The electric current flowed through in circuit is flowed through with the phase more late than the voltage applied to load circuit.

In addition, to common branch and exterior loop branch road switch element export drive signal than by exterior loop It is variable in the range of the resonant frequency of the load circuit that 11c and resonating capacitor 24d are constituted driving frequency higher, control into The electric current flowed through in load circuit is flowed through with the phase more late than the voltage applied to load circuit.

Next, the control of the access electric power (firepower) of branch road of the explanation based on inverter circuit 23 phase difference each other Braking is made.

Figure 18 is a figure for example of the drive signal of the full-bridge circuit for showing implementation method 3.

Figure 18 (a) is the example of the energization timing of the drive signal and each heating coil of each switch under firepower state high.

Figure 18 (b) is the example of the energization timing of the drive signal and each heating coil of each switch under low firepower state.

In addition, the output point (tie point of IGBT and IGBT) of Figure 18 (a) and be powered timing and each branch road shown in (b) Current potential difference correlation, the output point for representing common branch with " conducting " uses with respect to the output point and exterior loop of interior loop branch road The lower state of the output point of branch road.In addition, representing that the output point of common branch is defeated with respect to interior loop branch road with " cut-off " Go out a little and exterior loop branch road output point state and current potential identical state higher.

As shown in figure 18, control unit 45 exports being total to than load circuit to the IGBT232a and IGBT232b of common branch The drive signal of vibration frequency high frequency higher.

In addition, control unit 45 exports to interior loop branch the phase drive signal more advanced than the drive signal of common branch The IGBT231a and IGBT231b on road, the IGBT233a and IGBT233b of exterior loop branch road.In addition, the drive signal of each branch road Frequency be same frequency, conducting dutycycle is also identical.

For the output point (tie point of IGBT and IGBT) of each branch road, the ON-OFF state according to IGBT and IGBT, High frequency ground switches and exports the positive bus-bar current potential or negative busbar current potential as the output of DC power supply circuit.Thus, to interior lines Circle 11b applies the potential difference of the output point of common branch and the output point of interior loop branch road.In addition, applying to exterior loop 11c The potential difference of the output point of common branch and the output point of exterior loop branch road.

Therefore, by making the drive signal to common branch and the driving to interior loop branch road and exterior loop branch road The phase difference increase and decrease of signal, can adjust the high frequency voltage applied to interior loop 11b and exterior loop 11c, can control including The high frequency output electric current and input current flowed through in coil 11b and exterior loop 11c.

In the case of making firepower increased, the phase α between increase branch road, the voltage application time in 1 cycle of increase Width.In addition, the upper limit of the phase α between branch road is the situation of anti-phase (180 ° of phase difference), output voltage waveforms now into It is substantially rectangular ripple.

In the example of Figure 18 (a), it is illustrated that the phase α between branch road is 180 ° of situation.In addition, it is illustrated that each branch road The conducting dutycycle of drive signal be ON time T13a and deadline T13b in 50% situation, i.e. 1 cycle T 13 Ratio identical situation.

In this case, in 1 cycle T 14 of drive signal, the energization ON time of interior loop 11b, exterior loop 11c Width T14a and deadline width T14b that is powered are identical ratio.

In the case where firepower reduction is made, compared to firepower state high, reduce the phase α between branch road, in making 1 cycle Voltage application time width reduce.In addition, the lower limit on the phase α between branch road, such as bearing according to when connecting The relation of phase of electric current for flowing through etc. in circuit is carried, be set as being destroyed without flow through super-high-current in switch element etc. Level.

In the example of Figure 18 (b), it is illustrated that the situation of the phase α between branch road is reduced compared to Figure 18 (a).Separately Outward, the frequency and conducting dutycycle of the drive signal of each branch road are identical with Figure 18 (a).

In this case, in 1 cycle T 14 of drive signal, the energization ON time of interior loop 11b, exterior loop 11c Width T14a is phase α between branch road corresponding time.

In such manner, it is possible to pass through branch road phase difference each other, the access electric power to interior loop 11b, exterior loop 11c is controlled (firepower).

In addition, in the above description, illustrate to make interior loop 11b and exterior loop 11c all carry out plus thermally operated situation, But the driving of interior loop branch road or exterior loop branch road can also be stopped, in only making interior loop 11b or exterior loop 11c One party carries out heating action.

Control unit 45 is when the often regulation of the input current illustrated in above-mentioned implementation method 1 (or coil current) is sought Between time variation amount Δ I when, in the state of the driving frequency for securing inverter circuit 23, by the phase α between branch road Fixed state is set to the conducting dutycycle of the switch element of each branch road.In addition, other actions and the phase of above-mentioned implementation method 1 Together.

Thereby, it is possible in the state of being constant to the access electric power of interior loop 11b, exterior loop 11c, obtain input current The time variation amount Δ I of per stipulated time of (or coil current).

In addition, in present embodiment 3, by coil current detection unit 25c and coil current detection unit 25d, point The coil current flowed through in interior loop 11b and the coil current flowed through in exterior loop 11c are not detected.

Therefore, in the case where making interior loop 11b and exterior loop 11c all carry out heating action, even if in coil electricity One party in stream detection unit 25c or coil current detection unit 25d cannot detection coil current value due to failure etc. In the case of, it is also possible to by the detected value of the opposing party, the time variation amount Δ I of per stipulated time of detection coil electric current.

In addition, control unit 45 can also respectively obtain the every of the coil current that is detected by coil current detection unit 25c Per stipulated time of the time variation amount Δ I of stipulated time and the coil current detected by coil current detection unit 25d Time variation amount Δ I, a side larger in use time variation delta I, carries out what is illustrated in above-mentioned implementation method 1 respectively Each judgement action.Alternatively, it is also possible to using the average value of each time variation amount Δ I, carry out the explanation in above-mentioned implementation method 1 Each judgement action.

By carrying out such control, even if in coil current detection unit 25c or coil current detection unit 25d The accuracy of detection of some it is low in the case of, it is also possible to more precisely obtain the when anaplasia of per stipulated time of coil current Change amount Δ I.

In addition, in above-mentioned implementation method 1~3, as an example of induction heating cooking instrument of the invention, being cooked with IH Heater is adjusted for example is illustrated, but the invention is not restricted to this.The present invention can be applied to be added by sensing heating Electric cooker that heat is cooked etc. uses the arbitrary induction heating cooking instrument of induction heating mode.

Claims (14)

1. a kind of induction heating cooking instrument, it is characterised in that possess：

Heating coil, sensing heating is carried out to heating object；

Drive circuit, to the heating coil supply high frequency electric power；And

Control unit, controls the driving of the drive circuit, controls the RF power to heating coil supply,

The control unit obtains the input to the drive circuit in the state of the driving frequency for securing the drive circuit The time variation amount (Δ I) of at least one party in electric current and the coil current flowed through in the heating coil, measurement from Start to the heating coil supply electric power to the time variation amount (Δ I) as the very first time (t1) below setting value, According to the input current and the coil current in during the very first time (t1) and the very first time (t1) In at least one party current change quantity (I1), control to the heating coil supply RF power.

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

The very first time (t1) is shorter, the current change quantity (I1) is smaller, then the control unit makes to the heating coil The RF power of supply is smaller.

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

The very first time (t1) is shorter, the current change quantity (I1) is smaller, then the control unit is speculated as heating initial rank The thermic load of the content of the heating object in section is smaller, and the control unit is according to the thermic load for speculating, it is right to control The RF power of the heating coil supply.

4. the induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The control unit carry out from obtained in the state of the driving frequency for securing the drive circuit it is described when anaplasia Change amount (Δ I) turns into be risen second time that have passed through below the setting value (makes the height to heating coil supply after Δ t) The control of frequency electric power reduction, according to the very first time (t1) and current change quantity (I1), determines the second time (Δ t).

5. induction heating cooking instrument according to claim 4, it is characterised in that

The very first time (t1) is shorter, the current change quantity (I1) is smaller, then the control unit makes the second time (Δ T) it is shorter.

6. the induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The control unit carries out the time variation amount obtained in the state of the driving frequency for securing the drive circuit (Δ I) makes the driving frequency of the drive circuit increase, make to heating coil supply after turning into below the setting value RF power reduction control, according to the very first time (t1) and current change quantity (I1), the decision driving frequency Increment.

7. induction heating cooking instrument according to claim 6, it is characterised in that

The very first time (t1) is shorter, the current change quantity (I1) is smaller, then the control unit makes the driving frequency Increment is smaller.

8. the induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The control unit is made to institute by making the conducting dutycycle of the driving frequency of the drive circuit or switch element variable State the RF power reduction of heating coil supply.

9. the induction heating cooking instrument according to claims 1 or 2, it is characterised in that possess：

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

Notification unit,

The control unit drives institute in the case where the pattern of heating up water of the action of heating up water of setting water is selected as the pattern Drive circuit is stated, after the time variation amount (Δ I) turns into below the setting value, by the notification unit, is notified Heat up water the meaning for completing.

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

The control unit is more shorter than time reference value in the very first time (t1) and the current change quantity (I1) compares electric current In the case that a reference value is smaller, when the time variation amount (Δ I) turns into below the setting value, by the advice note Unit, notify to heat up water the meaning for completing.

11. induction heating cooking instrument according to claims 1 or 2, it is characterised in that

Possess the load identifying unit of the load determination processing for carrying out the heating object,

, according to the result of determination of the load identifying unit, the driving during setting driving drive circuit is frequently for the control unit Rate.

12. induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The control unit in the state of the driving frequency for securing the drive circuit, by the switch element of the drive circuit Conducting dutycycle be set to fixed state.

13. induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The drive circuit has been connected in series 2 full-bridge inverter circuits of the branch road of switch element by with least 2 Constitute,

The control unit, will in the state of the full-bridge inverter circuit, switch element driving frequency is secured The driving phase difference of the switch element each other of 2 branch roads and the conducting dutycycle of the switch element are set to Fixed state.

14. induction heating cooking instrument according to claims 1 or 2, it is characterised in that

The drive circuit is constituted by with the half-bridge inverter circuit for being connected in series 2 branch roads of switch element,

The control unit, will in the state of the half-bridge inverter circuit, switch element driving frequency is secured The conducting dutycycle of the switch element is set to fixed state.