JPH10172746A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a material of a load to be determined speedily and precisely. SOLUTION: Inverter circuit 1 is composed of a heating coil 12, a capacitor 15, and an IGBT(insulated gate bipolar transistor) 13 or the like, powered from an AC power circuit 3 via a DC power circuit 2, and driven and controlled by a control circuit 16. An input current and a recursive current are detected by an input current detecting circuit 23 and a recursive current detecting circuit 25, and on/off control of the IGBT 13 is performed by a calculation process circuit 22. The calculation process circuit 22 gradually increases an oscillation level of the inverter circuit 1, judges a no-load state or a stainless pot or the like from an input current detection data value when a recursive current detection data value reaches a given level, and judges the presence of a hollow pot when input current detection data reaches a threshold value before the recursive current detection data value reaches a given level. Between the input current and the recursive current, there is specific relationship according to a material of a pot P depending upon input power or frequency, therefore, a material can be judged simply and precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonance circuit in which a DC output from a DC power supply circuit via a smoothing capacitor is supplied to a resonance circuit including a resonance coil and a resonance capacitor by controlling on / off of the resonance circuit by switching means. To generate an eddy current in the cooking utensil mounted on the resonance coil portion and heat the cooking utensil.

[0002]

Conventionally, as an inverter device of this type, an output obtained by converting an AC power supply into a DC power supply is turned on / off by controlling a switching circuit of a resonance circuit composed of a resonance circuit and a capacitor. For example, there is an inverter circuit that is provided as an inverter circuit that resonates and thereby obtains an AC output. For example, a resonance coil is provided as a heating coil, and induction heating is performed using a conductive pot as a load.

[0003] In such a case, it is general that the way of the eddy current induced by the resonance coil differs depending on the material of the pot as a load.
The heating situation of the pot also changes. Also, in response to such a situation, providing a different control pattern for the on / off control of the switching element of the inverter circuit depending on the material leads to an efficient heating operation.

Therefore, in such an electromagnetic cooker, the current flowing through the inverter circuit during the heating operation is detected to determine the material of the pan. In this case, the current flowing through the inverter circuit is the same as the input current flowing from the DC power supply circuit side and the reverse current flowing through the flywheel diode connected in anti-parallel to the switching element when the switching element is off in the on / off control of the switching element, that is, the regenerative current. It is performed by detecting the current, and it is known that the level of the regenerative current with respect to the input current varies depending on the material and size of the pan, so determine the material by setting a certain standard Will be able to

However, if the power input at that time fluctuates due to fluctuations in the power supply voltage or the oscillation frequency when performing the above-described material determination, the values of the input current and the regenerative current are changed. May fluctuate from a predetermined level, which may fluctuate before and after the threshold value in some cases, leading to a problem that an erroneous determination occurs. Therefore, in order to prevent such a problem, measures such as correcting the detected value of the input current or the regenerative current each time according to the value of the input voltage, or changing the threshold value according to the input voltage, are taken. It is necessary to perform the operation, and as a result, a new problem occurs in that the configuration and control contents for drive control of the inverter circuit are complicated.

Further, in the above-described configuration, the material is determined by comparing the detection data of the input current and the detection data of the regenerative current separately. Therefore, correction is performed for each detection data, or the determination criterion is set. Processing such as matching is required, and there is a problem that the material determination method becomes complicated. further,
Since the above-described material determination operation is performed after the control output circuit is in a stable state, there is a problem that it takes time from when the load material determination is performed to when the heating operation is performed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inverter device capable of quickly and accurately determining the material of a load placed on a resonance coil portion of an inverter circuit. Is to provide.

[0008]

According to the first aspect of the present invention, there is provided an inverter device connected to a DC power supply circuit including a rectifier circuit and a smoothing capacitor, a resonance circuit including a resonance coil and a capacitor, a switching element, and anti-parallel thereto. An inverter circuit that includes a diode and converts a DC output of the DC power supply circuit into an AC output; a control unit that drives and controls the switching element so that high-frequency induction heating is performed on a load by the resonance coil; and the DC power supply circuit. Input current detecting means for detecting an input current of the regenerative current, regenerative current detecting means for detecting a regenerative current of the inverter circuit,
Determining means for determining a material of the load based on an input current detected by the input current detection means and a regenerative current detection value detected by the regenerative current detection means in an operation state of the inverter circuit; It has the characteristic in the place where it did (claim 1).

According to the above configuration, when the drive of the inverter circuit is controlled by the control unit, the determination unit determines the input current and the regenerative current detected by the input current detection unit and the regenerative current detection unit. The material of the load is determined.

At this time, the pot or the like as a load is electrically connected to the resonance coil and is heated by the eddy current supplied from the inverter circuit. At this time, the connection between the load and the resonance coil is increased. Varies depending on the material of the load, and this causes the heating operation to differ. This also causes differences in the values of the input current and the regenerative current flowing in the inverter circuit, and the values of the detected data have characteristic values depending on the material, and furthermore, they depend on the input power and frequency of the inverter circuit. Can be obtained as a characteristic. The determining means can determine the material of the load by finding the relationship between the two values having the characteristic value of the material of the load from the detection data of the input current and the regenerative current.

In the above configuration, the determination means may be configured to perform an operation of determining the material of the load prior to performing the energization control of the inverter circuit.

As described above, when determining the material of the load, the relationship between the characteristic input current and the regenerative current, which differs according to the material, is determined from the detected data, so that the output characteristics of the inverter circuit are stable. Since it is not necessary to perform the determination operation after waiting until, the determination operation can be performed in the initial stage of the energization control to the inverter circuit, and thereby, the inverter circuit can perform the determination without knowing the material of the load. It is not necessary to perform the heating operation in the rated input power state, and the operation of determining the material can be quickly performed, and the control operation of the inverter circuit suitable for the material of the load can be quickly performed.

[0013] Further, the determining means may be configured to perform the determining operation based on the value of the input current detected by the input current detecting means when the value of the regenerative current detected by the regenerative current detecting means reaches a predetermined value. (Claim 3).

According to this configuration, the determining means determines the value of the input current detected by the input current detecting means when the input power is sequentially increased until the regenerative current detected by the regenerative current detecting means reaches a predetermined value. , The material of the load is determined. In this case, the characteristic relationship between the input current and the regenerative current that differs depending on the material of the load described above is such that if the regenerative current detection data is set to a predetermined value, only the input current detection data can be obtained as different values. Therefore, by providing an appropriate threshold value, it is possible to determine detection data of different input currents according to the material of the load.

[0015] The determination means may determine whether the value of the input current detected by the input current detection means exceeds a determination level before the regenerative current detected by the regeneration current detection means reaches a predetermined value. May be configured to determine that the load is a specific material (claim 4).

With this, when the input power is increased until the detection data of the regenerative current reaches a predetermined level when the material of the load is determined by the above-described method, when the detection data of the input current exceeds the determination level, Then, the determination means can determine that the load is a specific material. This is because even if the regenerative current does not reach the predetermined level, if the input current does not exceed the judgment level except for a load of a specific material, the load of the load is not increased at that point without further increasing the input power. Since the material can be determined, the determination operation is performed there, whereby the specific material can be quickly determined.

The determining means may be configured to perform the determining operation based on a value of the regenerative current detected by the regenerative current detecting means when a value of the input current detected by the input current detecting means reaches a predetermined value. (Claim 5).

According to the above construction, the determining means determines the value of the regenerative current detected by the regenerative current detecting means when the input power is sequentially increased until the input current detected by the input current detecting means reaches a predetermined value. , The material of the load is determined. In this case, the material of the load is determined by obtaining the value of the regenerative current when the input current reaches a predetermined value by utilizing the characteristic relationship between the input current and the regenerative current described in the description of the third aspect. Is what you do.

[0019] The determination means may determine whether the value of the regenerative current detected by the regenerative current detection means exceeds the determination level before the input current detected by the input current detection means reaches a predetermined value. May be configured to determine that the load is a specific material (claim 6).

Thus, when the input power is increased until the detection data of the input current reaches a predetermined level when the material of the load is determined by the above-described method, when the detection data of the regenerative current exceeds the determination level, Then, the determination means can determine that the load is a specific material. This is because, even if the input current does not reach the predetermined level, if the regenerative current does not exceed the determination level other than the load of a specific material, the load of the load is not increased at that point without further increasing the input power. Since the material can be determined, the determination operation is performed there, whereby the specific material can be quickly determined.

In addition, when the determination means determines that the load is improper by the determination operation, the determination means is configured to repeatedly perform the determination operation after a lapse of a predetermined time. Preferably, the heating control is performed after the load is determined to be appropriate by the determination unit (claim 7).

According to the above configuration, for example, when a pot made of an appropriate material is not placed as a load at a position corresponding to the resonance coil, the heating control is not immediately stopped at that point, but for a predetermined time. Since the determination operation is performed again after elapse of the time, for example, even if the user starts the heating operation before placing the pan as the load, the appropriate pan is placed until the predetermined time elapses. By doing so, it becomes possible to start the heating control, it is possible to save the trouble of operating the operation switch each time, and, moreover,
When no load is placed or when an improper load is placed, the heating control is not performed, so that usability can be improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electromagnetic cooker will be described below with reference to the drawings.
FIG. 1 schematically shows an electrical configuration, in which a DC power supply circuit 2 constituting a power supply of an inverter circuit 1 includes an AC power supply circuit 3.
Is rectified by a full-wave rectifier circuit 4 as a rectifier circuit, and the rectified output is applied between the DC power supply lines 2a and 2b via a smoothing choke coil 5. The power supply lines 2a and 2b The configuration is such that a smoothing capacitor 6 is connected between them.

The AC power supply circuit 3 includes AC power supply lines 3a and 3b for receiving the output of a commercial AC power supply through a power supply plug 7, a power switch 8 and a fuse 9, and a varistor 10 between the power supply lines 3a and 3b. And the noise prevention capacitor 11 is connected.

The inverter circuit 1 is of a single-end type, in which a heating coil 12 as a resonance coil and a collector-emitter of an IGBT 13 as a switching element are connected to DC between DC power lines 2a and 2b, and rectified. The flywheel diode 14 as an element is connected in an anti-parallel state with the IGBT 13, and further, a resonance capacitor 15 is connected in parallel with the heating coil 12. The heating coil 12 is for linking a high-frequency magnetic field to the pot P as a conductive load.

Next, the configuration of the control circuit 16 for controlling the drive of the inverter circuit 1 will be described. The oscillation control circuit 17 controls the IGBT 13 of the inverter circuit 1 by PWM.
On / off control is performed based on a signal, and includes a timing circuit 18, an oscillation circuit 19, an output control circuit 20, and a gate drive circuit 21.

The above-described timing circuit 18 includes the IGBT 1
A timing signal for performing an on / off operation while minimizing the switching loss of No. 3 is generated based on the collector voltage of the IGBT 13, and the timing signal is supplied to the oscillation circuit 19 to control the oscillation timing. The oscillating circuit 19 is configured to generate a saw-tooth wave signal Sc serving as a carry signal of the PWM signal.
The output control circuit 20 generates a square wave PW based on a comparison between the above-mentioned sawtooth signal Sc and an output reference level signal Sref from an arithmetic processing circuit 22 as control means described later.
Generate an M signal. The gate drive circuit 21 includes the PWM
The signal is amplified and applied to the gate of the IGBT 13 to perform switching control by a pulse width modulation method.

The input current detecting circuit 23 as an input current detecting means includes a current transformer 23a interposed in a power supply line 3b in the AC power supply circuit 3, and a device based on a secondary output of the current transformer 23a. The entire input current is detected, and an input current detection signal Sin having a voltage level corresponding to the detected current value is supplied to the arithmetic processing circuit 22.

The input voltage detecting circuit 24 as input voltage detecting means has a series circuit of detecting resistors 24a and 24b connected between the AC power line 3a and the DC power line 2b. An input voltage to the device is detected based on a voltage signal generated at a common connection point between 24a and 24b, and an input voltage detection signal Sv of a voltage level corresponding to the detected voltage is supplied to the arithmetic processing circuit 22. I have.

A regenerative current detecting circuit 25 as regenerative current detecting means detects a regenerative current based on a secondary side output of a current transformer 25a interposed to detect a current flowing through the flywheel diode 14, and detects the regenerative current. The configuration is such that a regenerative current detection signal Sk of a voltage level corresponding to the detection voltage is provided to the arithmetic processing circuit 22.

The operation section 26 has a function of instructing the operation of the inverter circuit 1 and setting an output, and has an output setting signal S of a voltage level corresponding to the output setting.
ps is given to the arithmetic processing circuit 22. The arithmetic processing circuit 22 is constituted by a microcomputer, and has a program stored in advance to control the inverter circuit 1 as described later.

In the arithmetic processing circuit 22, the input current detection signal Sin from the input current detection circuit 23, the input voltage detection signal Sv from the input voltage detection circuit 24, and the regenerative current detection signal Sk from the regenerative current detection circuit 25 The output level reference signal Sref is generated based on a comparison result with the output setting signal Sps from the operation unit 26, and the output level reference signal Sref is supplied to the output control circuit 20 described above. .

The arithmetic processing circuit 22 converts the regenerative current detection signal Sk supplied from the regenerative current detection circuit 25 into the input current detection signal Sin supplied from the input current detection circuit 23 as input current detection data proportional to the input current. The data is handled as regenerative current detection data proportional to the regenerative current. For example, when the input current detection data value is “100”, the input current is about 8 A, and when the regenerative current detection data value is “125”, the regenerative current has a peak value of about 40 A. .

The above-mentioned arithmetic processing circuit 22 also has a function as a judging means. As described later, the material of the pot P is judged, and an inverter is controlled by an appropriate control pattern corresponding to the judgment result. IGBT1 of circuit 1
3 is turned on and off. At this time, it is also determined whether or not there is a pot P as a load. When it is determined that there is no load, the cooking control is not performed.

Next, the operation of the present embodiment will be described with reference to FIGS. First, while the pot P is placed on the heating coil 12 and the power switch 8 is turned on and the operation of the inverter circuit 1 is commanded through the operation unit 26, the arithmetic processing circuit 22 causes the input voltage detection circuit 2
4 determines whether or not the detected data value of the input voltage to the AC power supply circuit 3 input from the AC power supply 4 is within an appropriate range, and if it is appropriate, a material determination control operation for determining the material of the pot P thereafter. Execute

In the case of determining the input voltage detection data, the arithmetic processing circuit 22 determines that the rated input voltage is 10
If the voltage is 0 V, the appropriate range is from 80 V to 120 V.
A range of about V is set, and when it is within this range, it is determined to be appropriate. This means that when the input voltage is out of the appropriate range described above, the input current becomes excessively large or the overvoltage is applied to control the input power to a predetermined level during the drive control of the inverter circuit 1, This is to prevent the IGBT 13 from being broken or damaged.

Next, at the time of the above-described material determination control operation, the arithmetic processing circuit 22 outputs a low level to the output control circuit 20 in the oscillation control section 17 so that the input current and the regenerative current of the inverter circuit 1 are stabilized. Output level reference signal Sr
ef. Thereafter, the arithmetic processing circuit 22 gradually increases the output level reference signal Sref, and determines the material of the pot P as a load based on a detection principle described later.

In this case, in the oscillation controller 17, when the output level reference signal Sref is input from the arithmetic processing circuit 22, the output control circuit 20 performs a comparison operation with the triangular wave signal Sc input from the oscillation circuit 19. To generate a PWM signal. When the level of the output level reference signal Sref increases, the duty ratio of the PWM signal increases, and the ON period of the IGBT 13 increases.

In the inverter circuit 1, the IGBT 1
When the PWM signal 3 is given to such a PWM signal to perform an on / off operation, the heating coil 12 performs a resonance operation. At this time, current flows from the DC power supply circuit 2 through the heating coil 12 during the ON period of the IGBT 13 in the inverter circuit 1, and a resonance circuit is formed by the heating coil 12 and the resonance capacitor 15 during the OFF period of the IGBT 13. However, in this state, charging and discharging of the resonance capacitor 15 is performed through the heating coil 12, and particularly during discharge, the voltage between the collector and the emitter of the IGBT 13 becomes substantially zero and the resonance capacitor 15 is discharged.
When the discharge from the power supply is stopped, the DC power supply circuit 2 is connected through the flywheel diode 14 and the heating coil 12.
A regenerative current flows through the smoothing capacitor 6 on the side.

At this time, the regenerative current flowing through the flywheel diode 14 is detected as a voltage signal by the current transformer 25a, and is output by the regenerative current detection circuit 25 to the arithmetic processing circuit 22 as a signal Sk indicating detection data K of the regenerative current. become. When the drive of the inverter circuit 1 is controlled in this way, the AC power supply circuit 3
The current of the AC power supply input from the
Is detected as a voltage signal by the input current detection circuit 23.
As a result, a signal Sin indicating the detection data I of the input current is output to the arithmetic processing circuit 22. Further, the voltage detection circuit 24 outputs the voltage of the AC power supply input to the AC power supply circuit 3 to the arithmetic processing circuit 22 as a voltage signal Sv obtained by dividing the voltage by the detection resistors 24a and 24b.

Next, the operation of judging the material of the pot P as a load will be described. The arithmetic processing circuit 22 performs a determination operation based on the following detection principle from the input current detection data output from the input current detection circuit 23 and the regenerative current detection data output from the regenerative current detection circuit 25 as described above. Do.

First, as a suitable material for the pot P, for example, an enamel or stainless steel (SUS) is recommended as a standard material, and conversely, a material having a high conductivity such as aluminum is used. In this case, the regenerative current becomes large and the heat generation efficiency becomes low. In this case, the pot is considered to be inappropriate. Further, even if the material is enamel or stainless steel, a load that is improper in size as a pot P such as a cup or a spoon and is substantially in a no-load state is also excluded as inappropriate. There is a need.

Now, with the above-mentioned materials of the pot P, there is a relationship as shown in FIG. 2 between the detected data value of the input current and the detected data value of the regenerative current. That is,
When the oscillating operation of the inverter circuit 1 is started and the input current and the regenerative current gradually increase, the value of the ratio according to the material of the pot P, that is, the slope of the characteristic line indicating the relationship between the two generally depends on each. It is determined that the input current and the regenerative current increase along the characteristic straight line of the slope as the input power increases.

For example, when a proper enamel pan is used as the pan P, the input current detection data tends to be larger than the regenerative current detection data. Conversely, when a stainless steel pan is used, The tendency is that the detected data of the regenerative current becomes larger than the detected data of the input current.
Also, when an aluminum frying pan, which is an example of an inappropriate pot P, is used or when there is no load, only the detected data of the regenerative current increases and the detected data of the input current hardly increases. . Such a tendency is that even if the input power or the frequency to the inverter circuit 1 fluctuates, such characteristics have stable characteristics without being greatly affected by such fluctuation.

Therefore, utilizing the characteristics as described above, for example, by obtaining the detection data of the input current when the detection data of the regenerative current reaches a certain value, the enamel pan, the stainless steel pan and the inappropriate A pot or a substantially no-load condition can be determined. On the contrary, the determination operation can be performed by utilizing the similar characteristics by obtaining the detection data of the regenerative current when the detection data of the input current reaches a certain value.

Then, as shown in FIG. 3, for example, the arithmetic processing circuit 22 outputs the output level reference signal Sref while increasing the input current and the regenerative current until the input current and the regenerative current are stabilized (time t1). The level of Sref is gradually increased, and the drive of the inverter circuit 1 is controlled so that the detected data value of the regenerative current reaches a predetermined level K (see FIGS. 3B and 3C).

When the detected data value of the regenerative current reaches the predetermined level K, the arithmetic processing circuit 22 inputs the detected data of the input current at that time, and is set in advance as shown in FIG. The material is determined by comparing it with the threshold values L1 and L2 for determination. At this time, pot P
Is an enamel pan, for example, the detection data value of the input current exceeds the threshold value L1 to determine that the enamel pan is appropriate. If the detected data value of the input current is equal to or less than the threshold value L1 but exceeds the threshold value L2, it is determined that the stainless steel pot is used. Further, when the detected data value of the input current is equal to or less than the threshold value L2, it is determined that the pot is inappropriate.

In the above case, the time until the detected data value of the regenerative current reaches the predetermined level K differs depending on the material of the pot P. For example, in the case of the enamel pot, the time t2
On the other hand, in the case of the stainless steel pot, it is time t3 later than that. This indicates that the degree of increase in the regenerative current varies depending on the material of the pot P.

In practice, therefore, in the arithmetic processing circuit 22, threshold values are set for both the detection data of the input current and the detection data of the regenerative current, and the output of the inverter circuit 1 is gradually increased. The drive control is performed so that the material is determined when any of the input current detection data and the regenerative current detection data output at that time exceeds a set threshold value.

The arithmetic processing circuit 22 supplies the oscillation control circuit 17 with the output level reference signal Sref so that the output of the inverter circuit 1 gradually increases. At this time, the arithmetic processing circuit 22 increases the level of the output level reference signal Sref with the target of the value of the regenerative current detection data being, for example, “80” which is a threshold value.

If the rises of the regenerative current detection data and the input current detection data are both smaller than the level of the output level reference signal Sref, the arithmetic processing circuit 22
Determines that there is no load or that a substantially proper pan has not been placed, and that there is no load. In addition, the value of the regenerative current detection data increases according to the level of the output level reference signal Sref and reaches the above-described threshold value “80”, but the value of the input current detection data exceeds “70” which is the hollow determination level. If there is no, the value of the input current detection data at that time is a threshold value for determining the stainless steel pan, for example, “4”.
If it exceeds "0", it is determined that the stainless steel pot is used.

Further, the value of the regenerative current detection data is "8
If the value of the input current detection data exceeds “70” before reaching “0”, the arithmetic processing circuit 22 can determine that the pot P is an enamel pot, so that the determination operation is terminated here. Become.

Thereafter, the arithmetic processing circuit 22 outputs the output level reference signal Sref in accordance with the result of the determination of the material of the pot P, controls the oscillation operation of the inverter circuit 1, and performs the heating operation. Thereby, the pot P placed on the heating coil 12 can be heated in an appropriate control state.

In the above case, the arithmetic processing circuit 22
In the determination of the material quality of the pot P, when an inappropriate pot or no load state is determined, the subsequent heating operation is not stopped, but the determination operation is repeatedly performed at intervals of several seconds, for example. If the result is inappropriate, the start of the heating operation is stopped. Thus, for example, even when the user inadvertently turns on the operation switch for starting heating before placing the pot P, the heating operation can be performed when the appropriate pot P is placed. .

According to this embodiment, the material processing operation is performed by the arithmetic processing circuit 22 before the inverter circuit 1 is driven and controlled to perform the heating operation. The material is determined using the characteristic relationship between the correlation between the input current detection data and the regenerative current detection data according to the material of the input power. The material determination operation can be performed without being adversely affected by the above, and can be performed easily and quickly without performing complicated processing such as correcting input current detection data and regenerative current detection data and shifting a threshold value. The material of the load can be determined.

According to the present embodiment, the arithmetic processing circuit 2
2, when it is determined that the material of the pot P as the load is inappropriate, the determination operation is performed again to determine whether the proper pot P
Since the heating operation can be performed at the time when is placed, the usability is improved, and the heating operation can be stopped in an inappropriate pot P or in an unloaded state.

Further, according to the present embodiment, when the input voltage from the input voltage detection circuit 24 is out of the predetermined range, the drive control of the inverter circuit 1 is stopped by the arithmetic processing circuit 22. Therefore, it is possible to prevent the IGBT 13 of the inverter circuit 1 from being damaged by applying an overvoltage or flowing a large current.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. Although the input current detection data and the regenerative current detection data are handled as peak value data, average values may be used.
Performing a repeated determination operation when the no-load state is determined may be adopted as necessary. As the switching means, a field effect transistor, a bipolar transistor, or the like can be used in addition to the IGBT.

[0059]

As described above, according to the inverter device of the present invention, the following effects can be obtained. According to the inverter device of the first aspect, the coupling state between the load and the resonance coil differs depending on the material of the load, thereby causing a difference in the input current and the regenerative current flowing through the inverter circuit and having a characteristic value. Utilizing this, the determination means finds the relationship between the input data and the regenerative current, both of which have characteristic values for the load material, based on the detected data, and performs the load material determination. It is possible to determine the material of the load from the values of the detection data of the input current and the regenerative current as characteristics independent of the input power and the frequency of the input current and the regenerative current. There is an excellent effect that it is not necessary to adopt a complicated configuration such as changing the threshold value.

According to the inverter device of the second aspect,
When determining the material of the load, the relationship between the characteristic input current and the regenerative current, which differs according to the material, is determined from the detection data. Therefore, the determination operation must be performed after the output characteristics of the inverter circuit have stabilized. Without having to do
This eliminates the need for the inverter circuit to perform the heating operation in the rated input power state without knowing the material of the load, and quickly performs the material judgment operation to control the inverter circuit that is suitable for the load material. It has an excellent effect that it can be performed promptly.

According to the inverter device of the third aspect,
The determining means sequentially increases the input power until the regenerative current detection data detected by the regenerative current detection means reaches a predetermined value, and determines the material of the load from the value of the input current detection data detected by the input current detection means. Since the judgment is made, only the detection data of the input current is compared with the threshold based on the characteristic relationship between the input current and the regenerative current that differs depending on the material of the load, so that the material of the load can be easily judged. The effect is excellent.

According to the inverter device of the fourth aspect,
In the above case, when the detection data of the input current exceeds the determination level, the determination means determines that the load is a specific material, so that the time for determining the specific material can be reduced. become able to.

According to the inverter device of the fifth aspect,
The determining means sequentially increases the input power until the detection data of the input current detected by the input current detection means reaches a predetermined value, and determines the material of the load from the value of the detection data of the regeneration current detected by the regeneration current detection means. Since the judgment is made, only the detection data of the input current is compared with the threshold based on the characteristic relationship between the input current and the regenerative current that differs depending on the material of the load, so that the material of the load can be easily judged. The effect is excellent.

According to the inverter device of the sixth aspect,
In the above case, when the detection data of the regenerative current exceeds the determination level, the determination means determines that the load is a specific material, so that the time for determining the specific material can be reduced. become able to.

According to the inverter device of the seventh aspect,
When it is determined by the determining operation that the load is improper, the determining means is made to repeatedly perform the determining operation after a lapse of a predetermined time, and when it is determined that the load is appropriate, the control means performs the subsequent heating control. Even if heating is started by forgetting to place the load on the resonance coil, it is possible to save the trouble of operating the operation switch again when the load is placed. When not mounted or when an improper load is mounted, the heating operation is not performed, so that an excellent effect that the usability can be improved can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic electrical configuration diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a correlation characteristic between an input current and a regenerative current obtained according to a material of a pot.

FIG. 3 is an operation explanatory view showing a temporal transition of a material determination operation.

[Explanation of symbols]

1 is an inverter circuit, 2 is an AC power circuit, 3 is a DC power circuit, 4 is a full-wave rectifier circuit (rectifier circuit), 5 is a smoothing choke coil, 6 is a smoothing capacitor, 12 is a heating coil (resonant coil), 13 Is an IGBT (switching element), 14 is a flywheel diode (rectifying element),
15 is a resonance capacitor, 16 is a control circuit, 17 is an oscillation control circuit, 22 is an arithmetic processing circuit (control means, determination means),
23 is an input current detection circuit (input current detection means), 23a
Is a current transformer, 24 is an input voltage detection circuit, and 24a, 2
4b is a detection resistor, 25 is a regenerative current detection circuit (regeneration current detection means), and 25a is a current transformer.

Claims (7)

[Claims] A DC power supply circuit comprising a rectifier circuit and a smoothing capacitor; a resonance circuit comprising a resonance coil and a capacitor; a switching element; and a diode connected in anti-parallel to the switching element. An inverter circuit that converts the output into an output; a control unit that drives and controls the switching element so that a high-frequency induction heating is performed on the load by the resonance coil; an input current detection unit that detects an input current of the DC power supply circuit; Regenerative current detecting means for detecting a regenerative current of the inverter circuit, based on an input current detected by the input current detecting means and a regenerative current detection value detected by the regenerative current detecting means in an operating state of the inverter circuit. Determining means for determining the material of the load. Over the other apparatus. 2. The inverter according to claim 1, wherein the determination unit performs a determination operation of a material of the load before causing the resonance coil to perform a heating operation by controlling an energization of the inverter circuit. apparatus. 3. The determination operation based on a value of an input current detected by the input current detection means when a value of a regenerative current detected by the regeneration current detection means reaches a predetermined value. The inverter device according to claim 1, wherein the inverter device is configured to perform the following. 4. The method according to claim 1, wherein the determining means determines that the value of the input current detected by the input current detecting means exceeds a determination level before the regenerative current detected by the regenerative current detecting means reaches a predetermined value. 4. The inverter device according to claim 3, wherein the load is configured to determine that the load is a specific material. 5. The determining operation based on a value of a regenerative current detected by the regenerative current detecting means when a value of an input current detected by the input current detecting means reaches a predetermined value. The inverter device according to claim 1, wherein the inverter device is configured to perform the following. 6. The method according to claim 1, wherein the regenerative current detected by the regenerative current detecting means exceeds a determination level before the input current detected by the input current detecting means reaches a predetermined value. 6. The inverter device according to claim 5, wherein the device is configured to determine that the load is a specific material. 7. When the determination means determines that the load is inappropriate by the determination operation, the determination means is configured to repeatedly perform the determination operation after a lapse of a predetermined time. The inverter device according to any one of claims 1 to 6, wherein when the load is determined to be appropriate by the means, the subsequent heating control is performed.