KR101905662B1 - Induction Heating Cooker for Heating Magnetic and Non-magnetic Containers - Google Patents

Abstract

The present invention relates to an induction heating cooker for magnetic and non-magnetic containers. The induction heating cooker for magnetic and non-magnetic containers comprises: a power supply unit (10) rectifying input AC power and providing DC power; an induction heating unit (20) inducing an eddy current in a cooking container to be heated by an electric induction effect by a magnetic field generated by a resonance current while resonating the DC power supplied through the power supply unit (10) to heat the food in the cooking container to a desired heating temperature; an inverter resonance unit (30) switching the DC power supplied from the power supply unit (10) depending on a switching control signal to provide the resonance current to the induction heating unit (20); a container characteristic determination unit (40) determining a load characteristic by detecting the resonance current provided to the induction heating unit (20) or determining the presence or absence of a load by detecting an input current; an inverter driving unit (50) outputting the switching control signal for controlling a switching element of the inverter resonance unit (30); and a switching control unit (60) controlling the inverter driving unit (50) so that the frequency of the switching control signal follows a resonance frequency determined by the inductance of the induction heating unit (20) depending on each cooking container. According to the present invention, even if a user does not select an operation mode depending on the cooking container, the induction heating cooker finds an optimum operating frequency and an output compensation value suitable for the material of the cooking container to heat the cooking container under an optimal condition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an induction heating cooker for a magnetic and non-

The present invention relates to an induction heating cooker for both magnetic and non-magnetic containers, and more particularly, to an induction heating cooker for a magnetic and non-magnetic container, And an induction heating cooker combined with a magnetic and non-magnetic container for heating the container by selecting an operating frequency and an output compensation value.

In recent years, an induction heating cooker capable of reducing indoor air pollution and room temperature rise due to the absence of waste gas emissions has been widely used. Such an induction range (hereinafter referred to as an " induction heating cooker & The energy efficiency and the safety are high.

However, since such an induction heating cooker is an induction heating system using an electric magnetic field after being converted into a high frequency wave, there is a disadvantage that only a metal container having a large amount of electromagnetic waves and having magnetic properties can be used and a cooking vessel such as a pot and glass can not be used.

In order to solve the disadvantage of the induction heating cooker as described above, the user can switch to the magnetic cooking vessel heating mode and the non-magnetic cooking vessel heating mode. In this heating mode, both the magnetic cooking vessel and the non- An induction heating cooker has been developed.

As an example of the conventional induction heating cooker, a driving control apparatus and method of a combined cooker disclosed in Japanese Patent Application Laid-Open No. 1999-002751 can be cited. In the induction heating cooker disclosed in this patent document, A ceramic plate provided on the bottom surface of the ceramic plate for transmitting a magnetic field and reflecting microwaves, and a shield plate disposed under the shield plate for induction heating cooking, A magnetron attached to an outer wall surface of a heating chamber in a microwave heating mode to supply microwave power to the microwave heating furnace; A relay for supplying input power to the working coil, and a relay for supplying the amount of current flowing to one side of the input power A rectifying section for rectifying the output voltage of the current detecting section to a DC voltage, and a rectifying section for comparing the voltage value inputted from the rectifying section with a reference voltage value to discriminate the type of the container And a control unit for outputting a control signal so as to be heated according to the determined container type.

With such a configuration, the induction heating cooker disclosed in the above patent document must directly adjust the heating mode according to whether the user is a magnetic cooking vessel or a non-magnetic cooking vessel, so that if the user improperly adjusts the heating mode, There is a problem that can not be done.

Also, in order to determine the type of cooking vessel in the magnetic cooking vessel heating mode, the type of the vessel is discriminated by comparing the voltage value input from the rectifying unit with the reference voltage value. However, the impedance of the induction heating unit differs depending on the permeability of the vessel material and the specific resistance. Therefore, the impedance of the induction heating part changes according to the size of the container and the position of the container, so that the resonance frequency and the frequency characteristic of the inverter resonance part are changed from time to time. Therefore, depending on the material of the cooking container, There is a problem that the user has to directly compensate for a decrease in heating efficiency, such as to increase the time for heating the cooking vessel or to increase the time for heating the cooking vessel.

In order to solve this problem, it is possible to configure the compensation values according to the material of the container in the induction heating cooker in advance and automatically apply it when setting the heating output. However, the compensation value according to the material of the container is determined by the material, There is a problem in that it is very difficult to set the value individually.

Furthermore, the non-magnetic cooking vessel of all kinds is not low in resistivity, and the cooking vessel made of stainless steel 304 material belongs to the non-magnetic vessel only in terms of permeability. However, since the specific resistance is rather close to the magnetic vessel, In case of non-magnetic container made of aluminum or copper, the specific resistance of the material is extremely small, so that the impedance of the induction heating part becomes too low, and the resonance frequency of the inverter resonance There is a possibility that the negative switching element is destroyed.

In addition, in order to prevent the resonance current from flowing too large in consideration of the above, the inductance of the induction heating unit must be designed to be a certain value or more in advance. When the impedance of the induction heating unit is made high inductance and low in electric resistance, There is a problem in that a frequency output can not be output even if the resonance frequency of the inverter resonance part is slightly deviated from the driving frequency because the frequency selectivity value is increased and the frequency characteristic is sensitively changed.

KR 10-1999-002751 A KR 10-1997-0014466 A KR 10-1999-010627 A KR 10-2010-0010392 A

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an induction heating cooker which is capable of providing an optimum operating frequency and an output compensation value suitable for a material of a cooking container, And to provide an induction heating cooker for both magnetic and non-magnetic containers capable of being cooked and cooked.

According to an aspect of the present invention, there is provided an induction heating cooker comprising: a power unit for rectifying an input AC power to provide a direct current; A induction heating unit for inducing an eddy current in a cooking vessel to be heated by an electric induction effect by a magnetic field generated by a resonance current while resonating a direct current power supplied through a power supply unit to heat the food in the cooking vessel to a desired heating temperature; An inverter resonance unit for switching the DC power supplied from the power supply unit according to a switching control signal to provide a resonance current to the induction heating unit; A container characteristic determination unit for determining a load characteristic by detecting a resonance current provided to the induction heating unit or by detecting an input current to determine the presence or absence of a load; An inverter driver for outputting a switching control signal for controlling a switching element of the inverter resonance part; And a switching control unit for controlling the inverter driving unit so that the frequency of the switching control signal follows the resonance frequency determined by the inductance of the induction heating unit according to each cooking vessel.

The switching control unit sweeps the driving frequency in the low output mode to detect the frequency characteristic of the load for judging the load characteristic when the heating is started and uses the frequency characteristic of the detected load to determine the characteristic of the cooking container, The frequency and the electrical resistance of the induction heating unit are analyzed and the driving frequency and the output compensation value corresponding to the cooking vessel are set using the analyzed resonance frequency and the electrical resistance of the induction heating unit.

Further, the present invention is characterized by comprising: an input current detecting unit for detecting a current supplied from a power supply unit by the container characteristic determining unit; A load presence / absence detector for detecting the presence or absence of a load in accordance with an amount of a current detected by the input current detector; A resonance current detector for detecting a resonance current flowing through the induction heating portion; And a load characteristic determination unit for detecting a load characteristic according to an amount of a current detected by the resonance current detection unit.

) 이하이면 비금속으로, 설정값(

) 이상이면 금속용기로 판정하여 판정 결과를 스위칭 제어부로 제공하고, 스위칭 제어부는 부하유무 판단부에서 판정한 결과가 비금속이면 구동주파수를 발생시키지 않도록 제어되며, 금속용기로 판정되면 출력은 최소로 설정한 상태에서 구동주파수를 스윕하면서 인버터 구동부를 통해 인버터 공진부를 구동하고, 공진전류 검출부는 유도가열부에 흐르는 공진전류의 양을 검출한 다음, 부하특성 판단부에 제공하며, 부하특성 판단부는 입력전류 검출부로부터 제공되는 신호를 분석하여 유도가열부에 흐르는 공진전류의 양이 최대로 되는 공진주파수(

)와 공진전류의 양이 최대치의

이 되는 2개의 구동주파수(

,

)를 각각 검출한 다음, 수학식 1, 2에 의해 인버터 공진부의 주파수선택도 값(

)을 계산하여 유도가열부가 가지게 되는 전기저항 성분(

)을 산출하는 것을 또 다른 특징으로 한다.Further, according to the present invention, when the magnitude of the signal provided from the input current detector is smaller than the set value

) Or less, the setting value (

), The switching control section is controlled so as not to generate the driving frequency when the result of the determination made by the load existence determination section is a non-metal, and when the metal container is determined, the output is set to the minimum The resonance current detector detects the amount of the resonance current flowing in the induction heating section and then provides the resonance current to the load characteristic determination section, The signal provided from the detection unit is analyzed to determine a resonance frequency at which the amount of the resonance current flowing in the induction heating column is maximized

) And the amount of resonance current is the maximum

The two driving frequencies (

,

), And then the frequency selectivity value of the inverter resonance part (

) To calculate the electric resistance component (

) Is calculated.

[Equation 1]

&Quot; (2) "

According to the present invention, even if the user does not directly set the operation method of the induction heating cooker according to the material of the cooking vessel, if the cooking vessel is placed on the induction heating cooker, the induction heating cooker can be placed between the magnetic vessel and the non- The analysis of the inherent resonance frequency and the electric resistance component of the cooking vessel of various materials of the stainless steel 304 series having the characteristic property is performed and the optimal operating frequency and the output compensation value suitable for the cooking vessel are set based on this, The heating condition (the operating frequency and the output compensation value) is not matched to the cooking vessel depending on the material of the cooking vessel, so that the cooking vessel is not heated properly, thereby solving the problem that it takes a long time to cook the food.

1 is a diagram showing an example of a conventional induction heating cooker,
FIG. 2 is a view showing an example of an induction heating cooker for both magnetic and non-magnetic containers according to the present invention,
3 is a graph showing the difference between the resonance current and the frequency according to the magnetic and non-magnetic containers,
4 is a flowchart illustrating an example in which the induction heating cooker is driven by the switching controller according to the present invention.

Hereinafter, the structure and operation of the present invention will be described in more detail with reference to the accompanying drawings showing preferred embodiments.

The present invention relates to an induction heating cooker for both magnetic and non-magnetic containers capable of automatically finding and preparing an optimum operating frequency and an output compensation value suitable for a material of a cooking container even if the user does not select an operation mode according to the cooking container 2, the induction heating cooker according to the present invention includes a power supply unit 10, an induction heating unit 20, an inverter resonance unit 30, a container characteristic determination unit 40, an inverter driving unit 50 and a switching control section 60.

The power supply unit 10 rectifies a commercial power supply (AC power supply) and supplies it as a direct current. Since the power supply unit 10 is well known and widely used in an induction heating cooker, a detailed description thereof will be omitted.

As shown in FIG. 2, the induction heating unit 20 is provided at one side of the power supply unit 10. The induction heating power supply unit 10 is provided with the induction heating unit 20, The eddy current is induced in the cooking vessel to be heated by the electric induction effect by the magnetic field so that the food in the cooking vessel is heated to the desired heating temperature.

The induction heating unit 20 includes a vertical magnetic field heating system (TF system) in which a magnetic field is generated and heated in a vertical direction of the cooking vessel. And a working coil installed on the upper side of the base plate for generating a magnetic field for induction heating. In this case, the working coil may have a diameter different from that of the working coil so as to uniformly and effectively heat the cooking vessel The working coils may be arranged concentrically with each other, or the working coils may be arranged in a spiral shape, or alternatively, the working coils may be arranged in a triangular, square or polygonal shape.

One side of the power supply unit 10 is provided with an inverter resonance unit 30 for switching the DC power supplied from the power supply unit 10 according to a switching control signal to provide a resonance current to the induction heating unit 20, A resonance current is supplied to the induction heating portion 20 by the heating coil 30 and a magnetic field is generated in the working coil of the induction heating coil 20.

The inverter resonance unit 30 includes a pair of resonance capacitors C1 and C2 and a pair of auxiliary resonance capacitors C3 and C4 as shown in FIG. 2, and a pair of resonance capacitors C1 and C2 function to maintain the continuous resonance state by the high frequency current together with the induction heating portion 20 and the pair of auxiliary resonance capacitors C3 and C4 serve as a switching element of the switching element To maintain the zero voltage switching state in order to improve the system efficiency and reduce the stress of the switching element.

A container characteristic determination unit 40 is provided at one side of the induction heating unit 20 and a resonance current provided to the induction heating unit 20 is detected by the container characteristic determination unit 40 to determine a load characteristic, The current is detected to determine whether the cooking vessel is a magnetic or non-magnetic body, and at the same time, the quality of the cooking vessel is determined.

2, the container characteristic determination unit 40 includes an input current detection unit 41 for detecting a current supplied from the power source unit 10, A load presence / absence determining unit 42 for detecting the presence or absence of a load, a resonance current detecting unit 43 for detecting a resonance current flowing in the induction heating unit 20, and a resonance current detecting unit 43 And a load characteristic judging section (44) for detecting the load characteristic.

) 이하이면 비금속으로, 설정값(

) 이상이면 금속용기로 판정하여 판정 결과를 후술하는 스위칭 제어부(60)로 제공하고, 스위칭 제어부(60)는 부하유무 판단부(42)에서 판정한 결과가 비금속이면 구동주파수를 발생시키지 않도록 제어하며, 금속용기로 판정되면 출력은 최소로 설정한 상태에서 구동주파수를 스윕하면서 후술하는 인버터 구동부(50)를 통해 인버터 공진부(30)를 구동하고, 공진전류 검출부(43)는 유도가열부(20)에 흐르는 공진전류의 양을 검출한 다음, 부하특성 판단부(44)에 제공하며, 부하특성 판단부(44)는 입력전류 검출부(41)로부터 제공되는 신호를 분석하여 유도가열부(20)에 흐르는 공진전류의 양이 최대로 되는 공진주파수(

)와 공진전류의 양이 최대치의

이 되는 2개의 구동주파수(

,

)를 각각 검출한 다음, 아래의 수학식 1, 2에 의해 인버터 공진부(30)의 주파수선택도 값(

)을 계산하여 유도가열부(20)가 가지게 되는 전기저항 성분(

)을 산출한다.At this time, the load presence / absence determining unit 42 determines whether the magnitude of the signal supplied from the input current detecting unit 41 is a set value

) Or less, the setting value (

, The switching control section 60 controls the switching control section 60 so as not to generate the driving frequency if the result of the determination made by the load presence / absence judgment section 42 is a non-metal The resonance current detection unit 43 drives the inverter resonance unit 30 through the inverter drive unit 50 to be described later while sweeping the drive frequency with the output set at the minimum, The load characteristic determination unit 44 analyzes the signal supplied from the input current detection unit 41 and supplies the result to the induction heating unit 20. The load characteristic determination unit 44 determines the resonance current flowing through the induction heating unit 20, The resonance frequency at which the amount of the resonance current flowing in

) And the amount of resonance current is the maximum

The two driving frequencies (

,

), And then calculates the frequency selectivity value of the inverter resonance unit 30 by the following equations (1) and

) To calculate an electric resistance component (hereinafter referred to as " electric resistance component "

).

는 주파수선택도 값이고,

는 공진주파수이며,

,

는 구동주파수이다.here,

Is a frequency selectivity value,

Is a resonant frequency,

,

Is the driving frequency.

은 전기저항 성분이고,

는 콘덴서

이며,

는 주파수선택도 값이고,

는 공진주파수이다.From here,

Is an electric resistance component,

The capacitor

Lt;

Is a frequency selectivity value,

Is the resonance frequency.

)는 가열될 조리용기에서 인버터 공진부(30)가 가지는 공진주파수로서 가열될 조리용기에 사용될 구동주파수로 선정되는데, 이때 가열될 조리용기가 자성 용기인 경우에는 재질의 투자율이 높으므로 유도가열부(20)의 인덕턴스가 높아져 20㎑ 근방의 저주파에서 공진이 주로 일어나고, 비자성 용기의 경우에는 재질의 투자율이 낮아 유도가열부(20)의 인덕턴스가 작아지므로 60㎑ 이상의 고주파에서 공진이 주로 일어나게 된다.In Equation (1), the resonance frequency

Is selected as the resonance frequency of the inverter resonance unit 30 in the cooking vessel to be heated at a driving frequency to be used for the cooking vessel to be heated. At this time, when the cooking vessel to be heated is a magnetic vessel, the permeability of the material is high, Resonance occurs mainly at a low frequency in the vicinity of 20 kHz because the inductance of the induction heating coil 20 is high and the magnetic permeability of the material is low in the case of a nonmagnetic container so that the inductance of the induction heating coil 20 becomes small, .

Since the resonance frequency varies depending on whether the cooking vessel is a magnetic body or a non-magnetic body, the resonance frequency also varies depending on the resistivity, size, and position of the cooking vessel material. It has a very wide variety of values.

)은 자성용기의 경우 비교적 큰 값을 가지는 반면, 비자성 용기(예를 들면, 알루미늄, 구리 등)의 경우 매우 작은 값을 가지게 되는데, 이를 통해 조리기의 가열 효율이 어느 정도로 될지 알 수 있기 때문에 조리용기에 따른 가열 출력 보상 값을 선정하는데 사용된다.The electrical resistance component (

) Has a relatively large value in the case of a magnetic container, whereas it has a very small value in the case of a non-magnetic container (for example, aluminum, copper, etc.) It is used to select the heating output compensation value according to the vessel.

An inverter driving unit 50 is provided on one side of the inverter resonance unit 30. A switching control signal for controlling the switching device of the inverter resonance unit 30 is output by the inverter driving unit 50. The inverter driving unit 50 drives the inverter resonance unit 30 while sweeping the driving frequency by continuously controlling the frequency for a predetermined time under the control of the switching control unit 60 to be described later.

A switching control unit 60 is provided between the container characteristic determination unit 40 and the inverter driving unit 50. The inductance of the induction heating unit 20 by the switching control unit 60 varies according to the inductance And the amount of the counter electromotive force generated by the electromagnetic induction due to the change in the current flowing in the circuit) is controlled by the inverter control unit 50 so that the frequency of the switching control signal follows.

)와 유도가열부(20)가 가지는 전기저항 성분(

)을 이용하여 가열될 조리용기에 적합한(맞는) 구동주파수와 출력 보상값을 설정하고, 인버터 구동부(50)를 통해 인버터 공진부(30)를 구동하여 조리용기를 본격적으로 가열하게 되는데, 이때 부하특성 분석을 위해 스위칭 제어부(60)는 구동주파수를 스윕하면서 인버터 구동부(50)를 통해 인버터 공진부(30)가 구동된다.The switching control unit 60 may control the resonance frequency of the resonance frequency analyzed by the load characteristic determination unit 44 of the container characteristic determination unit 40

) And the electric resistance component of the induction heating portion 20 (

The controller 50 sets the driving frequency and the output compensation value suitable for the cooking vessel to be heated and drives the inverter resonance unit 30 through the inverter driving unit 50 to heat the cooking vessel in earnest. The switching control unit 60 drives the inverter resonance unit 30 through the inverter driving unit 50 while sweeping the driving frequency.

The resonance current detection unit 43 detects the amount of resonance current flowing through the induction heating unit 20 and provides the resonance current to the load characteristic determination unit 44 so that the driving frequency can be precisely , A difference in driving frequency between adjacent steps is set to be small). In this case, however, there is a problem in that the time taken to analyze the load characteristics becomes too long.

Therefore, in order to shorten the time required for analyzing the load characteristics of the cooking vessel, the present invention preliminarily sets any reference value (i1, i2) of the driving frequency at the time of designing the induction heating cooker, The frequency sweep step value is set differently to the boundary.

More specifically, as shown in the graph of FIG. 3, when the amount of the resonant current detected is smaller than the reference value i1, the resonant current is swept in 5 kHz steps, and when the amount of the resonant current becomes larger than the reference value i1 When the frequency is reached, it is swept more tightly in 1 kHz steps and can be set to sweep more precisely in 100 Hz steps if the amount of resonant current exceeds the other reference value i2, thereby sweeping the driving frequency within a certain range It is possible to greatly shorten the time required to perform the operation.

)를 100㎐ 이내의 오차로 검출할 수 있으며, 공진전류의 양이 최대치의

이 되는 2개의 구동주파수(

,

)는 자성 용기의 경우 1㎑ 이내 오차로 검출할 수 있으며, 비자성 용기의 경우는 100㎐ 이내의 오차로 검출할 수 있다.At this time, the size and the number of the respective step widths and reference values are appropriately selected according to the characteristics of the cooking container, the inverter driving unit 50, and the target precision of the designer, whereby the resonance frequency

) Can be detected with an error within 100 Hz, and the amount of the resonance current is maximum

The two driving frequencies (

,

) Can be detected with an error within 1 kHz in the case of a magnetic container, and within 100 Hz in the case of a non-magnetic container.

When using the induction heating cooker having both the magnetic and non-magnetic containers of the present invention configured as described above, when the user puts the cooking container on the induction heating cooker and starts heating as shown in FIG. 4, 60 drives the inverter resonance unit 30 through the inverter driving unit 50 while setting the driving frequency to the initial low frequency and the input current detection unit 41 of the container characteristic determination unit 40 drives the inverter resonance unit 30 And provides it to the load presence / absence judgment unit 42. The load presence / absence judgment unit 42 detects the amount of current supplied to the load presence /

Then, after detecting the frequency characteristic of the load while sweeping the driving frequency in the low output mode, the resonance frequency and the electric resistance of the induction heating element 20 are measured using the frequency characteristic of the load detected earlier to determine the characteristics of the cooking vessel The resonance frequency and the electric resistance of the induction heating unit 20 are used to set a driving frequency and an output compensation value suitable for the cooking vessel, and then the cooking vessel is heated in earnest.

According to the present invention, even if the user does not set the cooking container separately according to the material of the cooking container, the user can automatically detect the characteristics of the cooking container and detect and set the optimum driving frequency and output compensation value accordingly, Is secured.

As described above, according to the present invention, even if a user uses a container of any material, the cooker can determine the material of the cooking container and can find and heat the optimum operating frequency and output compensation value for the cooking container by himself, The heating efficiency can be ensured and the user does not have to control the cooking vessel according to the type of the cooking vessel, which is convenient to use.

10: power source part 20: induction heating part
30: inverter resonance unit 40: container characteristic determination unit
41: Input current detection unit 42: Load presence / absence determination unit
43: resonance current detection unit 44: load characteristic determination unit
50: inverter drive unit 60: switching control unit
C1, C2, C3, C4: Capacitor CS1, CS2: Current sensor
SWD1, SWD2: Switching element

Claims (3)

A power supply unit 10 for rectifying an input AC power and providing the rectified AC power;
A induction heater for inducing an eddy current in a cooking vessel to be heated by an electric induction effect by a magnetic field generated by a resonance current while resonating a DC power supplied through the power source unit 10 to heat the food in the cooking vessel to a desired heating temperature 20);
An inverter resonance unit 30 for switching the DC power supplied from the power supply unit 10 according to a switching control signal to provide a resonance current to the induction heating unit 20;
A container characteristic determination unit (40) for determining a load characteristic by detecting a resonance current provided to the induction heating unit (20) or detecting an input current to determine the presence or absence of a load;
An inverter driving unit 50 for outputting a switching control signal for controlling a switching element of the inverter resonance unit 30;
And a switching control unit (60) for controlling the inverter driving unit (50) so that the frequency of the switching control signal follows the resonance frequency determined by the inductance of the induction heating unit (20) according to each cooking vessel,
When the heating is started, the switching control unit 60 sweeps the driving frequency in the low output mode to determine the load characteristic, detects the frequency characteristic of the load,
In order to determine the characteristics of the cooking vessel, the resonance frequency and the electric resistance of the induction heating unit are analyzed using the frequency characteristics of the detected load,
And controlling the driving frequency and the output compensation value corresponding to the cooking vessel by using the analyzed resonance frequency and the electrical resistance of the induction heating unit, and then heating the electromagnetic frequency and the non-magnetic cooking vessel.
delete The method according to claim 1,
The container characteristic determination unit 40 includes an input current detection unit 41 for detecting a current supplied from the power supply unit 10; A load presence determining unit (42) for detecting the presence or absence of a load in accordance with the amount of the current detected by the input current detecting unit (41); A resonance current detection unit 43 for detecting a resonance current flowing through the induction heating unit 20; And a load characteristic determination unit (44) for detecting a load characteristic according to an amount of a current detected by the resonance current detection unit (43).

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