JP3985503B2 - Induction heating cooker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating cooker, and more particularly to a cooker for induction heating a load made of a low resistance metal such as aluminum or copper.
[0002]
[Prior art]
Hereinafter, a conventional induction heating cooker will be described with reference to FIG. The commercial power source 1 is rectified by the rectifying element 2, DC power is supplied to the inverter 4 by the smoothing means 3, and the inverter 4 drives the switching element 7 to generate a high-frequency magnetic field in the heating coil 6 and induces the load 5. It is for heating. Here, frequency control has been performed in order to control power to the load 5. That is, the frequency control is performed by changing the drive frequency of the switching element 7. Here, in order to detect the temperature of the load 5, a temperature detection element such as a thermistor (not shown) is provided on the top plate of the cooking device.
[0003]
[Problems to be solved by the invention]
The induction heating cooker having the conventional configuration has a large thermal time constant of the temperature detection unit for detecting the temperature of the load 5, and a detection delay with respect to a temperature change of the load 5 occurs. In addition, when the load is a low melting point metal such as aluminum, there is a problem that the load temperature detection is delayed and the load 5 may be damaged when the load temperature rises rapidly, such as by baking the load. Yes.
[0004]
The present invention solves the above-described conventional problems, and an object thereof is to provide an induction heating cooker that facilitates load temperature detection and has a stable inverter operation.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an induction heating cooker according to the present invention includes a heating coil for inductively heating a load, an inverter having a switching element and generating a high-frequency magnetic field from the heating coil, a resonant capacitor, aluminum, and copper. If such as induction heating loads of low resistance metal, in a state where the Q of the resonance of the heating coil and the resonance capacitor in the state of the load and the magnetic coupling is increased, the driving frequency before the SL switching element, Ya-off duty Control that fixes the input voltage of the inverter, and when the control target amount of the inverter or a change thereof exceeds or exceeds the control target range due to the fixation, the control target amount or the control that the change is set The switching element drive frequency, on / off duty and inverter input power are set to fall within the target range. An output control means for controlling to change the,
It has a load temperature detecting means for detecting the load temperature based on the frequency or the number of times that the control target amount exceeds or exceeds the control target range by being fixed.
[0006]
Thereby, it is possible to provide an induction heating cooker with good followability of load temperature detection.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is a heating coil for induction heating a load, an inverter having a switching element and generating a high frequency magnetic field from the heating coil, a resonance capacitor,
If inductively heating the load of the metallic aluminum or copper and low resistance, the load and in a state where Q of the resonance is increased in the heating coil and the resonant capacitor in a state where the magnetic bound, driving frequency before the SL switching element, When control is performed to fix the on / off duty and the input voltage of the inverter, and the control target amount of the inverter or its change exceeds or exceeds the control target range due to the fixation, the control target amount or its change Output control means for controlling the drive frequency, on-off duty, and inverter input voltage to change the switching element so that it falls within the set control target range, and the control target amount exceeds or exceeds the control target range by fixing Invitation to have load temperature detection means to detect load temperature according to the frequency or frequency With cooker, it provides the following capability of the load temperature detection is good induction heating cooker.
[0008]
According to a second aspect of the present invention, there is provided a heating coil for induction heating a load, an inverter having a switching element for generating a high frequency magnetic field from the heating coil, a resonance capacitor, and a load of a low resistance metal such as aluminum or copper. When induction heating is performed, control is performed to fix the driving frequency of the switching element, the on / off duty, and the input voltage of the inverter in a state where the resonance Q of the heating coil and the resonance capacitor in a magnetically coupled state with the load is increased. When the control target amount of the inverter or the change thereof exceeds or exceeds the control target range due to being fixed, the control target amount of the inverter or the change thereof is included in the set control target range. Control that changes the switching element drive frequency, on / off duty, and inverter input voltage. By using an induction heating cooker that has a load temperature detecting means that detects a change in the control target amount by detecting the change of the control target amount by fixing the output control means, the load temperature detection is easy to follow and easy to use. Provide a good induction heating cooker.
[0009]
The invention according to claim 3 displays or reports the load temperature detected by the load temperature detecting means, and the induction heating cooker according to claim 1 or 2 provides good followability of load temperature detection and cooking performance. A good induction heating cooker is provided.
[0010]
The invention according to claim 4 provides good followability in load temperature detection by using the induction heating cooker according to any one of claims 1 to 3 that performs output control of an inverter corresponding to the load temperature. Provide a safe induction heating cooker.
[0011]
The invention according to claim 5 is the induction heating cooker according to any one of claims 1 to 4, wherein the inverter is stopped when the load temperature detected by the load temperature detecting means becomes abnormally high. Provides a further safe induction heating cooker.
[0012]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
In FIG. 1, a commercial power source 11 is rectified by a rectifying element 12, DC power is supplied to an inverter 14 by a smoothing means 13, and the inverter 14 drives a switching element 17 to generate a high-frequency magnetic field in a heating coil 16. The load 15 such as a pot is induction-heated. In order to control the power to the load 15, the output control means 18 varies the drive frequency of the switching element 17 as a control target amount, and the input detection means 21 that detects the input current performs the input current control, thereby controlling the input current. The target amount is within the control target range. After the input current reaches the control target range, the drive frequency of the switching element 17 is fixed and the operation of the inverter 14 is stabilized.
[0014]
That is, when the control target amount controlled by the output control means 18 is fixed and the control target amount input to the output control means 18 or its change is detected to exceed or exceed the set control target range The amount to be controlled is changed. Further, the output control means 18 controls the output of the inverter 14 in accordance with the output of the load temperature detection means 19.
[0015]
FIG. 2 shows the drive frequency-input power characteristics of the induction cooking device of this embodiment. In this embodiment, a resonance capacitor is connected in series with the heating coil 16 to form a SEPP inverter. The input power characteristic has a peak resonance frequency of the heating coil 16 and the resonance capacitor. When a low resistance metal such as aluminum or copper is induction-heated as the load 15, the resonance Q of the heating coil 16 and the resonance capacitor in a state where the load 15 is magnetically coupled is large. The input power changes.
[0016]
The load 15 is continuously induction-heated, and the temperature of the load 15 rises. As the temperature of the load 15 rises, the Q of resonance between the heating coil 16 and the resonant capacitor decreases, and the input power characteristic changes as shown by the dotted line in the figure according to the temperature change. Since the drive frequency is fixed, the input current decreases according to the temperature change. When the load temperature further increases, it tends to exceed the control target range set in advance for the input current. At this point, the drive frequency, which is the amount to be controlled, is changed so that the input current falls within the control target range. By repeating this, the frequency or number of times the input current exceeds or exceeds the control target range can be detected by the load temperature detection means 19 and the temperature of the load 15 can be detected. Particularly when a low resistance metal such as aluminum or copper is induction-heated as the load 15, since the resonance Q of the heating coil 16 and the resonance capacitor in a state where the load 15 is magnetically coupled is large, the input power is steep with respect to the frequency. It can be easily realized to detect the change of the driving frequency, and no time delay is generated by the temperature detection unit. For this reason, the induction heating cooker with good followability of load temperature detection is realized.
[0017]
In addition, the temperature of the load 15 can be displayed by a liquid crystal or LED (not shown), or can be notified by an alarm sound or synthesized voice to inform the user of the load temperature at a high speed, thereby realizing an easy-to-use induction heating cooker. It is what.
[0018]
Further, by controlling the output by the output control means 18 according to the output of the load temperature detection means 19, an induction heating cooker with good cooking performance is realized, for example, the load 15 is rapidly heated until the load temperature reaches a certain temperature. is doing. Further, the load temperature detecting means 19 detects that the load temperature has become abnormally high, such as heating the load 15 in the absence of food, and the inverter 14 is stopped to stop heating to the load 15. In addition, a safe induction heating cooker is realized by preventing further increase in load temperature.
[0019]
Moreover, if a change in the control target value is detected without exceeding the control target range, the load temperature can be detected at a higher speed.
[0020]
In this embodiment, the inverter configuration is a so-called SEPP, but it is needless to say that it is not necessary to stick to this. In addition, although the control target amount is also the drive frequency in this embodiment, the effect of the present invention can be obtained also as the on / off duty of the switching element 17 and the input voltage of the inverter 14. Further, although the input current is set as a control target, the same effect can be obtained with the output current, the heating coil voltage and current, the voltage and current of the resonance capacitor, and the like. Further, it goes without saying that load temperature detection accuracy can be improved by using in combination with a temperature detection element such as a conventional thermistor or thermocouple.
[0021]
【The invention's effect】
As described above, the induction heating cooker according to the present invention realizes an induction heating cooker with good followability of load temperature detection.
[Brief description of the drawings]
FIG. 1 is a block diagram of an induction heating cooker according to an embodiment of the present invention. FIG. 2 is a drive frequency-input power characteristic diagram of the induction heating cooker. FIG. 3 is a block diagram of a conventional induction heating cooker. [Explanation of symbols]
14 Inverter 15 Load 16 Heating coil 18 Output control means 19 Load temperature detection means 21 Input detection means

Claims (5)

A heating coil for inductively heating the load, an inverter having a switching element and generating a high-frequency magnetic field from the heating coil, a resonant capacitor,
If inductively heating the load of the metallic aluminum or copper and low resistance, the load and in a state where Q of the resonance is increased in the heating coil and the resonant capacitor in a state where the magnetic bound, driving frequency before the SL switching element, When control is performed to fix the on / off duty and the input voltage of the inverter, and the control target amount of the inverter or its change exceeds or exceeds the control target range due to the fixation, the control target amount or its change Output control means for performing control to change the drive frequency of the switching element, the on / off duty and the input voltage of the inverter so as to fall within the set control target range;
An induction heating cooker having load temperature detecting means for detecting a load temperature based on a frequency or number of times that the control target amount exceeds or exceeds the control target range by being fixed. A heating coil for inductively heating the load, an inverter having a switching element and generating a high-frequency magnetic field from the heating coil, a resonant capacitor,
When induction load is applied to a low resistance metal load such as aluminum or copper, the switching element drive frequency and on / off are increased with the resonance Q of the heating coil and the resonance capacitor in a magnetically coupled state with the load. When the control to fix the duty and the input voltage of the inverter is performed and the control target amount of the inverter or the change exceeds or exceeds the control target range by fixing, the control target amount of the inverter or the change thereof Output control means for performing control to change the driving frequency of the switching element, the on / off duty and the input voltage of the inverter so as to fall within the set control target range,
An induction heating cooker having a load temperature detection means for detecting a change in the control target amount by fixing and detecting a load temperature.   The induction heating cooker according to claim 1 or 2, wherein the load temperature detected by the load temperature detecting means is displayed or notified.   The induction heating cooker according to any one of claims 1 to 3, wherein output control of the inverter corresponding to the load temperature detected by the load temperature detection means is performed.   The induction heating cooker according to any one of claims 1 to 4, wherein the inverter is stopped when the load temperature detected by the load temperature detection means becomes abnormally high.

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