Induction heater and controlling method thereof

Abstract

This induction heater may comprise: a plate on which a cooking container is located; a vibration sensor for sensing vibration of the cooking container; a heating coil for heating the cooking container; and a control unit, wherein the control unit increases the power level of the heating coil so that food contained in the cooking container is heated, acquires a first vibration pattern of the cooking container on the basis of vibration data of the vibration sensor, decreases the power level of the heating coil and maintains same for a predetermined period of time when the first vibration pattern satisfies a predetermined first condition, acquires a second vibration pattern of the cooking container after the predetermined period of time elapses, and can determine that the food is in a boiling state on the basis that the second vibration pattern satisfies a predetermined second condition.

Description

Induction heating device and its control method

[0001] The disclosed invention relates to an induction heating device and a control method thereof, and relates to an induction heating device including a heating coil and a control method thereof.

[0002] In general, an induction heating device is a cooking device that heats and cooks food using the principles of induction heating. An induction heating device comprises a cooking plate on which a cooking container is placed and a heating coil that generates a magnetic field when current is applied.

[0003] When current is applied to the heating coil, a magnetic field is generated, inducing a secondary current in the cooking vessel. This, in turn, generates Joule heat due to the vessel's own resistance. Consequently, the cooking vessel is heated by the high-frequency current, and the food contained within is cooked.

[0004] These induction heating devices use the cooking vessel itself as a heat source, so they have the advantage of high heat transfer, no generation of harmful gases, and no risk of fire compared to gas ranges or kerosene stoves that burn fossil fuels and heat the cooking vessel through the combustion heat.

[0005] In the past, the boiling point of water in a cooking vessel was determined by detecting the vibration of the cooking vessel containing the water.

[0006] However, in the actual usage environment of induction heating devices, various vibrations exist, making it difficult to extract only the vibrations related to water boiling, and it was not easy to accurately determine the boiling of water. Furthermore, there were limitations on the types of containers used to detect water boiling using vibration. For example, only enamel cookware with a thin layer of glassy ceramic on the metal surface could be used, and commonly used cookware such as ceramic-coated cookware, cast iron cookware, and non-stick cookware could not be used.

[0007] One aspect of the disclosed invention provides an induction heating device and a control method thereof that can more accurately and reliably detect boiling of food contained in a cooking vessel regardless of the type of the cooking vessel.

[0008] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0009] An induction heating device according to one aspect of the disclosed invention may include: a plate on which a cooking vessel is positioned; a vibration sensor for detecting vibration of the cooking vessel; a heating coil for heating the cooking vessel; and a control unit for increasing a power level of the heating coil so that food contained in the cooking vessel is heated, obtaining a first vibration pattern of the cooking vessel based on vibration data of the vibration sensor, and decreasing the power level of the heating coil and maintaining the heating coil for a predetermined period of time when the first vibration pattern satisfies a predetermined first condition, obtaining a second vibration pattern of the cooking vessel after the predetermined period of time has elapsed, and determining that the food is in a boiling state based on the second vibration pattern satisfying the predetermined second condition.

[0010] A control method for an induction heating device according to one aspect of the disclosed invention comprises: a control method for an induction heating device including a vibration sensor for detecting vibration of a cooking vessel positioned on a plate; and a heating coil for heating the cooking vessel, the control method comprising: increasing a power level of the heating coil so that food contained in the cooking vessel is heated; acquiring a first vibration pattern of the cooking vessel based on vibration data of the vibration sensor; reducing the power level of the heating coil and maintaining the power level for a predetermined period of time when the first vibration pattern satisfies a predetermined first condition; acquiring a second vibration pattern of the cooking vessel after the predetermined period of time has elapsed; and determining that the food is in a boiling state based on the fact that the second vibration pattern satisfies a predetermined second condition.

[0011] Figure 1 illustrates the appearance of an induction heating device according to one embodiment.

[0012] Figures 2 and 3 are drawings illustrating the heating principle of an induction heating device according to one embodiment.

[0013] Fig. 4 illustrates an example of a resonant circuit of an induction heating device according to one embodiment.

[0014] Fig. 5 is a block diagram showing the configuration of an induction heating device according to one embodiment.

[0015] Fig. 6 is a flowchart showing a control method of an induction heating device according to one embodiment.

[0016] Fig. 7 is a detailed flowchart showing a control method of an induction heating device according to one embodiment.

[0017] FIG. 8 is a graph showing changes in vibration intensity during a series of processes in which water contained in a cooking vessel boils in an induction heating device according to one embodiment.

[0018] FIG. 9 is a graph showing an example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0019] FIG. 10 is a graph showing another example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0020] FIG. 11 is a graph showing another example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0021] Fig. 12 is a graph showing the maximum value of vibration intensity over time when boiling food contained in a cooking container in an induction heating device according to one embodiment.

[0022] FIG. 13 is a graph showing an example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0023] FIG. 14 is a graph showing another example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0024] FIG. 15 is a graph showing another example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0025] It should be understood that the various embodiments and terms used in this document are not intended to limit the technical features described in this document to specific embodiments, but rather to include various modifications, equivalents, or substitutes of the embodiments.

[0026] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0027] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0028] In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0029] The term "and / or" includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0030] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0031] When a component (e.g., a first component) is referred to as being "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0032] The terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in this document, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0033] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0034] When we say that a component is "on" another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0035] Hereinafter, an embodiment according to the present invention will be described with reference to the attached drawings.

[0036] FIG. 1 illustrates the appearance of an induction heating device according to one embodiment, and FIGS. 2 and 3 are drawings for showing the heating principle of the induction heating device according to one embodiment.

[0037] FIG. 1 is a top view of an induction heating device (1) according to one embodiment. As shown in FIG. 1, the induction heating device (1) according to one embodiment may include a plate (110) provided on an upper portion of a main body (101), a cooking zone (111, 112, 113) formed on the plate (110), and a user interface (120, 130) functioning as an input / output device. As an example, the plate (110) may be made of ceramic.

[0038] Cooking zones (111, 112, 113) indicate the positions where cooking containers are placed, and may be represented by a circular shape as indicated by drawing 111 to guide proper placement of cooking containers, or by straight boundary lines as indicated by drawing 112, 113.

[0039] However, the shapes described above are merely examples of shapes for indicating the cooking zone (111, 112, 113), and can be applied to the embodiment of the induction heating device (1) even if it is not circular or straight, as long as it can guide the user to the location of the cooking zone.

[0040] In addition, although the example illustrates a case where three cooking zones are formed on the plate (110), the embodiment of the induction heating device (1) is not limited to this. It is also possible to form only one cooking zone, or it is also possible to form four or more cooking zones.

[0041] A display (120) and an input device (130) may be provided in one area of ​​the plate (110). The display (120) may include a display device such as an LCD or an LED, and the input device (130) may include at least one of various input devices such as a touch pad, a button, a jog shuttle, etc. Alternatively, the display (120) and the input device (130) may implement a touch screen.

[0042] In the present example, a case is exemplified where a display (120) and an input device (130) are provided at positions spaced apart from the cooking zones (111, 112, 113) on the plate (110). However, the arrangement of FIG. 1 is merely an example applicable to the induction heating device (1), and it is also possible for the display (120) or the input device (130) to be provided at a position other than the plate (110), such as the front of the heating cooking device (100).

[0043] Referring to FIGS. 2 and 3 together, a heating coil (240) may be placed on the lower portion of the plate (110) to heat a container (10) placed on the plate (110). For convenience of explanation, only one heating coil (240) is illustrated in FIGS. 2 and 3, but the number of heating coils (240) may be provided corresponding to the number of cooking zones.

[0044] In the case where there are three cooking zones (111, 112, 113) as in the example of Fig. 1, three heating coils (240) can also be provided, and each heating coil (240) can be placed below each cooking zone (111, 112, 113).

[0045] The heating coil (240) can be connected to a resonant circuit (2, see FIG. 4) described later, and a high-frequency current can be applied from the resonant circuit (2). For example, the frequency of the high-frequency current can be 20 kHz to 35 kHz.

[0046] When a high-frequency current is supplied to the heating coil (240), magnetic lines of force (ML) can be formed in the heating coil (240). When a container (10) having resistance is positioned within the range of the magnetic lines of force (ML), the magnetic lines of force (ML) around the heating coil (240) pass through the bottom of the container (10) and generate an eddy current, i.e., an eddy current (EC), in the form of an eddy current according to the law of electromagnetic induction.

[0047] Heat can be generated in the container (10) by the interaction of these eddy currents (EC) and the electrical resistance of the container (10), and the food inside the container (10) can be heated by the generated heat.

[0048] In an induction heating device (1) like this, since the container (10) itself acts as a heat source, a metal having a certain level of resistance or higher, such as iron, stainless steel, or nickel, can be used as the material of the container (10).

[0049] Meanwhile, the specifications of the heating coil (240) may be designed differently depending on the rated voltage of the country where the induction heating device (1) is sold.

[0050] Fig. 4 illustrates an example of a resonant circuit of an induction heating device according to one embodiment.

[0051] Referring to Fig. 4, the resonant circuit (2) may include a power supply (20).

[0052] The power supply unit (20) may include a power supply (ES) and a rectifier (210).

[0053] The power source (ES) is an AC power source (ES) and can supply power (ES) corresponding to the rated voltage.

[0054] The rectifier (210) can convert the AC voltage supplied from the power source (ES) into DC voltage.

[0055] To this end, the rectifier (210) may include a bridge rectifier circuit composed of a plurality of diodes. For example, the bridge rectifier circuit may include four diodes. The diodes may form diode pairs in which two diodes are connected in series, and the two diode pairs may be connected in parallel with each other. The bridge diode may convert an AC voltage whose polarity changes over time into a voltage whose polarity is constant, and may convert an AC current whose direction changes over time into a current whose direction is constant.

[0056] Additionally, the rectifier (210) may include a DC link capacitor. The DC link capacitor may convert a voltage whose magnitude varies over time into a DC voltage of a constant magnitude. The DC link capacitor may maintain the converted DC voltage and provide it to the inverter (SW1, SW1). At this time, the inverter (SW1, SW1) may include a first switching element (SW1) and a second switching element (SW1).

[0057] The first switching element (SW1) and the second switching element (SW1) can operate complementarily to each other to cause an alternating current to flow to the heating coil (240).

[0058] The first switching element (SW1) and the second switching element (SW1) can be implemented as a three-terminal semiconductor element switch with a fast response speed to be turned on / off at high speed. For example, the first switching element (SW1) and the second switching element (SW1) can be a bipolar junction transistor (BJT), a metal-oxide-semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or a thyristor.

[0059] The first switching element (SW1) and the second switching element (SW2) can be turned on / off by a switch driving signal. At this time, the switch driving signal can be provided by the control unit (150), and the control unit (150) can supply high-frequency alternating current to the heating coil (240) by alternately turning the first switching element (SW1) and the second switching element (SW2) on / off.

[0060] According to various embodiments, the resonant circuit (2) may further include a filter that removes noise components included in the power supplied from the power source (ES). The filter is composed of a transformer and a capacitor and can remove noise mixed in the power supplied from the power source (ES) and provide AC power with the noise removed to the rectifier (210).

[0061] Fig. 5 is a block diagram showing the configuration of an induction heating device according to one embodiment.

[0062] Referring to FIG. 5, an induction heating device (1) according to one embodiment may include a display (120), an input device (130), a vibration sensor (140), a control unit (150), a communication unit (160), and a resonance circuit (2).

[0063] The resonant circuit (2) may include a first switching element (SW1) and a second switching element (SW2), which are inverters (SW1, SW2).

[0064] The display (120) may display information regarding the current status of the induction heating device (1), information to guide the selection of a cooking zone or power level, and information to guide the setting of a timer. In addition, a notification indicating the presence or absence of a container (10) may be displayed.

[0065] The input device (130) can receive a selection command for the power level of the heating coil (240) from the user. When the control unit (150) receives a selection command for the power level of the heating coil (240) from the user through the input device (130), the control unit (150) can determine the on / off frequency of the first switching element (SW1) and the second switching element (SW2) based on the selected power level. The control unit (150) can apply a high-frequency current of a frequency corresponding to the selected power level to the heating coil (240) by alternately turning on / off the first switching element (SW1) and the second switching element (SW2) according to the determined on / off frequency.

[0066] The vibration sensor (140) can detect the vibration of the cooking container (10).

[0067] The vibration sensor (140) can detect the vibration of the cooking container (10) through the plate (110).

[0068] A vibration sensor (140) is provided on a plate (110) on which a cooking vessel (10) is placed and can detect vibration of the plate (110) corresponding to vibration of the cooking vessel (10).

[0069] When food in a cooking vessel (10) placed on a plate (110) is heated, flow of the food may occur. This flow of the food may physically affect the cooking vessel (10) and generate vibrations. The vibration of the cooking vessel (10) may be transmitted to the plate (110) on which the cooking vessel (10) is placed. The vibration sensor (140) detects the vibration of the plate (110) and thereby detects the vibration pattern of the cooking vessel (10) through the plate (110). Therefore, by analyzing the vibration pattern of the cooking vessel (10) that occurs during the boiling process of the food, it is possible to determine whether the food contained in the cooking vessel (10) is boiling.

[0070] The vibration sensor (140) can detect at least one of the X-axis acceleration, Y-axis acceleration, or Z-axis acceleration of the cooking container (10).

[0071] The vibration sensor (140) may be a single-axis acceleration sensor that detects any one of the X-axis acceleration, Y-axis acceleration, or Z-axis acceleration of the cooking vessel (10).

[0072] The vibration sensor (140) may be a two-axis acceleration sensor that detects two of the X-axis acceleration, Y-axis acceleration, or Z-axis acceleration of the cooking container (10).

[0073] The vibration sensor (140) may be a three-axis acceleration sensor or a three-axis MEMS (Micro Electro Mechanical System, MEMS) sensor that detects all of the X-axis acceleration, Y-axis acceleration, and Z-axis acceleration of the cooking container (10).

[0074] The vibration sensor (140) can collect sensor data regarding the vibration of the cooking vessel (10). For example, the vibration sensor (140) can obtain the acceleration of an axis corresponding to the vibration of the cooking vessel (10).

[0075] In one embodiment, the control unit (150) can obtain at least one of the X-axis acceleration, the Y-axis acceleration, or the Z-axis acceleration of the cooking vessel (10) based on the vibration data, which is an output value of the vibration sensor (140). The control unit (150) can obtain the acceleration of at least one axis of the cooking vessel (10) based on the vibration data processed by the vibration sensor (140). For example, the control unit (150) can obtain at least one of the X-axis acceleration, the Y-axis acceleration, or the Z-axis acceleration of the cooking vessel (10) based on the vibration data of the vibration sensor (140).

[0076] The communication unit (160) may include at least one of a short-range communication module or a long-range communication module.

[0077] The communication unit (160) can transmit data to an external device or receive data from an external device. For example, the communication unit (160) can establish communication with a server, a user device, and / or other home appliances, and transmit and receive various types of data.

[0078] To this end, the communication unit (160) can support the establishment of a direct (e.g., wired) communication channel or a wireless communication channel between external devices, and the performance of communication through the established communication channel. According to one embodiment, the communication unit (160) can include a wireless communication module (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module (e.g., a local area network (LAN) communication module, or a power line communication module). Among these communication modules, the corresponding communication module can communicate with the external device through a first network (e.g., a short-range communication network such as Bluetooth, wireless fidelity (WiFi) direct, or infrared data association (IrDA)) or a second network (e.g., a long-range communication network such as a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., a LAN or WAN)). These different types of communication modules may be integrated into a single component (e.g., a single chip) or implemented as multiple separate components (e.g., multiple chips).

[0079] The short-range wireless communication module may include, but is not limited to, a Bluetooth communication module, a BLE (Bluetooth Low Energy) communication module, a near field communication module, a WLAN (Wi-Fi) communication module, a Zigbee communication module, an infrared (IrDA, infrared Data Association) communication module, a WFD (Wi-Fi Direct) communication module, an UWB (ultrawideband) communication module, an Ant+ communication module, a microwave (uWave) communication module, etc.

[0080] The long-distance communication module may include a communication module that performs various types of long-distance communication and may include a mobile communication unit. The mobile communication unit transmits and receives wireless signals with at least one of a base station, an external terminal, and a server on a mobile communication network.

[0081] In one embodiment, the communication unit (160) can communicate with external devices such as a server, user devices, and other home appliances via a surrounding access point (AP). The access point (AP) can connect a local area network (LAN) to which the induction heating device (1), other home appliances, and / or user devices are connected to a wide area network (WAN) to which the server is connected. The induction heating device (1), other home appliances, and / or user devices can be connected to the server via the wide area network (WAN).

[0082] The control unit (150) can control the operation of the induction heating device (1).

[0083] The control unit (150) may include at least one memory (152) storing a program for performing the operations described below and at least one processor (151) executing the stored program.

[0084] At least one processor (151) may include a microprocessor. A microprocessor is a processing device having an arithmetic logic unit, a register, a program counter, an instruction decoder, a control circuit, etc., provided on at least one silicon chip.

[0085] Microprocessors may include a graphics processing unit (GPU) for processing images or videos. Microprocessors may be implemented as a system-on-chip (SoC) that includes cores and a GPU. Microprocessors may include single-core, dual-core, triple-core, quad-core, or multiples thereof.

[0086] Additionally, at least one processor (151) may include an input / output processor that mediates data input and output between various components included in the induction heating device (1) and the control unit (150).

[0087] At least one memory (152) may include non-volatile memory such as ROM, high-speed random access memory (RAM), magnetic disk storage, flash memory device, or other types of non-volatile semiconductor memory devices.

[0088] For example, at least one memory (152) may include one of a Secure Digital (SD) memory card, a Secure Digital High Capacity (SDHC) memory card, a mini SD memory card, a mini SDHC memory card, a Trans Flash (TF) memory card, a micro SD memory card, a micro SDHC memory card, a memory stick, a Compact Flash (CF), a Multi-Media Card (MMC), an MMC micro, and an XD (eXtreme Digital) card as a semiconductor memory device.

[0089] Additionally, at least one memory (152) may include a network attached storage device that is accessed via a network.

[0090] The control unit (150) can control the induction heating device (1) based on user input received through the input device (130). For example, the input device (130) can receive user input regarding power (ES) on / off, selection of cooking zones (111, 112, 113), selection of power level of heating coil (240) of selected cooking zone, timer setting, etc.

[0091] For example, the control unit (150) can select a heating coil (240) to supply high-frequency power based on the selection of a cooking zone received through the input device (130), and can adjust the strength of the magnetic field generated by the heating coil (240) based on the selection of the power level received by the input device (130). However, in the case where the induction heating device (1) includes only one cooking zone, it goes without saying that the power level can be selected directly without selecting the cooking zone.

[0092] The control unit (150) may increase the power level of the heating coil (240) so that the food contained in the cooking vessel (10) is heated, obtain a first vibration pattern of the cooking vessel (10) based on the vibration data of the vibration sensor (140), and when the first vibration pattern satisfies a predetermined first condition, decrease the power level of the heating coil (240) and maintain it for a predetermined time, obtain a second vibration pattern of the cooking vessel (10) after the predetermined time has elapsed, and determine that the food is in a boiling state based on the fact that the second vibration pattern satisfies the predetermined second condition.

[0093] The control unit (150) can display the boiling status of the food through the display (120).

[0094] The control unit (150) can output a message indicating that the food is in a boiling state on the display (120) or display the boiling progress based on the boiling state of the food.

[0095] The control unit (150) can control the communication unit (160) to transmit a signal notifying an external device of the boiling state of the food based on the boiling state of the food. The external device may include a server, a user device (e.g., a smartphone), another home appliance, etc.

[0096] For example, a signal indicating the boiling state of the food can be transmitted to a user device possessed by a user of the induction heating device (1) via a server.

[0097] The external device can output sensory information (e.g., image, vibration, sound, etc.) indicating the boiling state of the food through its output interface based on receiving a signal indicating the boiling state of the food.

[0098] For example, if the external device is a smartphone, the smartphone may output a notification message, vibration, and / or sound based on receiving a signal indicating the boiling status of the food.

[0099] Fig. 6 is a flowchart showing a control method of an induction heating device according to one embodiment.

[0100] Referring to FIG. 6, the control unit (150) can increase the power level of the heating coil (240) so that the food contained in the cooking vessel (10) is heated (300).

[0101] The control unit (150) can obtain the first vibration pattern of the cooking vessel (10) based on the vibration data of the vibration sensor (140) (302).

[0102] The control unit (150) can determine whether the first vibration pattern satisfies a predetermined first condition (304).

[0103] The predetermined first condition is a condition under which the food contained in the cooking vessel (10) is assumed to boil as the cooking vessel (10) is heated. For example, the predetermined first condition can be determined based on the vibration intensity slope.

[0104] The control unit (150) can reduce the power level of the heating coil (240) and maintain it for a predetermined time when the first vibration pattern satisfies a predetermined first condition (306).

[0105] The control unit (150) can obtain the second vibration pattern of the cooking vessel (10) after a predetermined time has elapsed (308).

[0106] The control unit (150) can determine whether the second vibration pattern satisfies a predetermined second condition (310).

[0107] The predetermined second condition may be a condition that determines that the food contained in the cooking vessel (10) is boiling. For example, the predetermined second condition may be determined based on at least one of the vibration intensity and the vibration intensity slope.

[0108] The control unit (150) can determine that the food contained in the cooking vessel (10) is in a boiling state when the second vibration pattern satisfies a predetermined second condition (312).

[0109] The food may be a food containing liquid. For example, the food may be a stew, soup, porridge, curry, water, etc.

[0110] For convenience of explanation, the cooking medium is assumed to be water.

[0111] Fig. 7 is a detailed flowchart showing a control method of an induction heating device according to one embodiment.

[0112] Referring to FIG. 7, the induction heating device can be divided into an initial heating control step (400), a correction data acquisition step (402), a container heating detection step (404), a maximum slope detection step (406), a boiling candidate detection step (408), a power level reduction and maintenance step (410), a boiling confirmation step (412), and a boiling control step (414).

[0113] In the initial heating control step (400), an operation for stabilizing the vibration state of the induction heating device (10) can be performed because the boiling of the food is determined by using the vibration pattern of the cooking vessel (10) detected through the plate (110).

[0114] The initial heating control step (400) is a preparatory step for acquiring correction data. In the initial heating control step (400), the control unit (150) can initially control the inverter (SW1, SW2) and the cooling fan of the induction heating device (1). The cooling fan can introduce external air into the interior of the induction heating device (1) so as to cool the internal components of the induction heating device (1).

[0115] In the initial heating control step (400), when the temperature of the induction heating device (1) increases during the process of boiling water, the cooling fan operates. The strength of the cooling fan may vary depending on the internal temperature of the induction heating device (1). When the cooling fan operates or the strength of the cooling fan varies, the vibration strength of the plate (110) of the induction heating device (1) may also vary.

[0116] When the power level of the heating coil (240) is set, the inverter (SW1, SW2) may operate, causing vibrations. Since these vibrations are unrelated to the vibrations that occur when water boils, they may interfere with the detection of boiling water.

[0117] Therefore, the inverters (SW1, SW2) operate, but the vibrations in a state where water does not boil can be measured and used as a basis for correction. Since correction data is acquired in the next step, the correction data acquisition step (402), the power level can be controlled to an appropriate level for obtaining the correction data.

[0118] It can be experimentally confirmed that the main frequency band of vibration occurring when the power level of the heating coil (240) is low is not significantly different from the band when the power level is high.

[0119] Therefore, in the initial heating control step (400), the power level may be low to check the frequency band of the inverters (SW1, SW2). Control can be made at the maximum power level at which water does not boil. Generally, if the correction is made based on the power level at which water actually boils, accuracy can be improved. However, if the power level is high in the correction data acquisition step (402), the accuracy of the correction may be reduced due to vibrations caused by the cooking vessel (10) heating up or the water evaporating.

[0120] For example, in the case of power levels 1 to 9, in the initial heating control step (400), power level 4 (initial power level) can be set.

[0121] In the initial heating control step (400), a preset waiting period may be maintained to stabilize the vibration of the inverter (SW1, SW2) and the cooling fan. For example, a waiting period of 5 seconds may be maintained after the inverter (SW1, SW2) and the cooling fan are turned on.

[0122] The correction data acquisition step (402) can acquire correction data that corrects the vibration pattern by excluding the vibration component generated in the induction heating device (1) in the initial heating step (400) after acquiring the vibration pattern of the cooking vessel (10). That is, among the vibration patterns of the cooking vessel (10), correction data composed of only vibration components excluding the vibration components of the inverter (SW1, SW2) and the cooling fan that are unrelated to the vibration generated when water boils can be acquired. For reference, the correction data can also be used as a name referring to the vibration components of the inverter (SW1, SW2) and the cooling fan that are unrelated to the vibration generated when water boils.

[0123] In the correction data acquisition step (402), the frequency and intensity mainly generated from vibrations generated in the inverter (SW1, SW2) and cooling fan of the induction heating device (1) can be used as a basis for correction.

[0124] In the correction data acquisition step (402), the power level can be maintained at power level 4, the same as in the initial heating step (400).

[0125] In the correction data acquisition step (402), the vibration sensor (140) used to acquire the vibration pattern of the cooking vessel (10) is an accelerometer sensor that can detect acceleration for each of the X-axis, Y-axis, and Z-axis movements that occur on the plate (110) when the cooking vessel (10) is heated.

[0126] The control unit (150) can detect only the movement of one axis because, if it detects all of the X-axis, Y-axis, and Z-axis movements occurring in the plate (110) through the vibration sensor (140), it requires a lot of calculations in the system. For example, among the X-axis, Y-axis, and Z-axis movements occurring in the plate (110), only the Z-axis movement can be used for calculations.

[0127] The vibration sensor (140) can provide acceleration values ​​for each axis. The sign of the acceleration value can indirectly indicate the direction of movement. The period at which the sign of the acceleration value changes can indicate the period of the main vibration. Although multiple vibrations acting on the vibration sensor (140) interfere with each other and the signal is amplified or canceled, the period at which the sign changes can ultimately follow the vibration period of the strongest vibration. The size of the acceleration value can indirectly indicate the intensity of the vibration. The size of the acceleration value can increase as the signal is amplified or canceled due to multiple vibrations interfering with each other, but ultimately, as the vibration increases, the size of the sensor value can also increase.

[0128] The control unit (150) can convert time axis data received from the vibration sensor (140) for a certain period of time into frequency axis data through fast Fourier transform (FFT).

[0129] For example, you can perform an FFT based on the most recently received 512 data points. This could mean that the FFT size is 512.

[0130] Since the FFT size is 512, it can be separated into 257 (512 / 2 + 1) frequency bands. If 1000 data are obtained per second from the vibration sensor (140), theoretically, up to 500 Hz can be confirmed.

[0131] By computing the FFT for the most recent 512 samples with an FFT operation cycle (e.g., 250 ms), we can find out the magnitude of each of the 257 frequency domains.

[0132] In the correction data acquisition step (402), sample data for correction can be acquired. The intensities of all frequency bands can be stored over a predetermined period of time (e.g., 5 seconds). Then, reference data for correction can be generated through calculations in subsequent steps.

[0133] For example, since the FFT is calculated at a 250ms cycle, 20 FFTs (5,000 / 250) would be calculated over 5 seconds, and since the intensity for 257 frequency domains can be known for each FFT, a total of 5,140 (20*257) sample data for correction can be stored.

[0134] In the correction data acquisition step (402), after acquiring sample data for correction, a representative value for each frequency band can be determined. For example, since 20 data points for each frequency band are acquired over a period of 5 seconds, a representative value for each can be determined. Each representative value can be an average or median.

[0135] For example, the median can be applied as each representative value. During the 5 seconds of data acquisition, significant vibrations may occur due to the surrounding environment. For example, closing the lid of a cooking vessel (10), placing a cutting board on the sink, or slamming the door of a nearby refrigerator can cause significant vibrations. This noise is characterized by significant fluctuations in values. Therefore, taking the average can lead to significant errors. The median is useful for eliminating large, intermittent noises because it completely excludes values ​​with significant fluctuations.

[0136] It is also possible to take the minimum value or a value near it assuming that the sample data for correction is stable in a normal vibration environment.

[0137] In the correction data acquisition step (402), unnecessary frequency bands can be identified. Frequency bands to be excluded can be identified based on the representative value of each frequency band. The frequency of vibrations generated by the operation of cooling fans or inverters (SW1, SW2) can be identified and excluded. These two frequency bands of vibration affect the intensity of the vibrations generated when water boils, sometimes amplifying and sometimes canceling out, which can interfere with the determination of the boiling trend of water.

[0138] Even if there is a specific frequency that reacts significantly when water boils, it is not easy to detect the trend if it overlaps with the frequency of the inverter (SW1, SW2). To avoid amplification or cancellation with the external environment, it can be completely ignored. In other words, the purpose of the induction heating device (1) according to one embodiment is not to intensively check the frequency at which water boils, but to preemptively block the band that interferes with the vibration generated when water boils and examine the trend of the remaining band. Therefore, this band is checked in the correction data acquisition step (402).

[0139] This can be determined by the following four criteria:

[0140] First, the 19 low-frequency bands can be ignored. For example, the 0 Hz to 35 Hz band can be ignored. Experimentally, no trend in intensity was observed in this region as water boiled. As the water boiled, the intensity sometimes increased and sometimes decreased.

[0141] Second, 24 high-frequency bands can be ignored. For example, the 455 Hz to 500 Hz band can be ignored. Experimentally, no change in intensity was observed in this region when water boiled.

[0142] Third, the top 16 bands with the highest intensity can be ignored. Excluding the bands ignored in the first and second steps, the remaining bands are sorted in descending order of intensity, and the bands with the highest number (e.g., the top 16) can be ignored. This is because at this point, a band with a high intensity is likely to be affected by an external force unrelated to boiling water.

[0143] Fourth, regions where the intensity suddenly increases and jumps compared to adjacent regions can be ignored. This process involves finding regions whose absolute intensity is not high enough to be ignored in the third step, but whose intensity is relatively high compared to adjacent regions. This is because a region with a high intensity at this point likely represents an external force unrelated to boiling water.

[0144] In the correction data acquisition step (402), correction data can be generated.

[0145] When setting the representative value for each frequency band, the median was calculated to determine the representative value for each band. The bands to be excluded were determined based on the four criteria mentioned above. The bands not excluded and their representative values ​​can be used as a basis for correction.

[0146] The container heating detection step (404) may be a step for checking whether the cooking container (10) is sufficiently heated.

[0147] In the container heating detection step (404), the water begins to be heated at a high power level. The power level can be set to 9.

[0148] As the temperature of the cooking vessel (10) rises, water contained in the cooking vessel (10) that comes into direct contact with the cooking vessel (10) may begin to evaporate. As water evaporates more, increasingly stronger vibrations may occur. By detecting this vibration state using a vibration sensor (140), the heating state of the cooking vessel (10) can be detected.

[0149] Before explaining the container heating detection step (404) in detail, the method for calculating the reference value of the vibration intensity and the method for calculating the slope of the vibration intensity will first be explained.

[0150] First, we explain how to calculate the reference value of vibration intensity.

[0151] A reference value for vibration intensity is constantly calculated throughout the water boiling detection algorithm and can be one of the targets of comparison for step transitions.

[0152] FIG. 8 is a graph showing changes in vibration intensity during a series of processes in which water contained in a cooking vessel boils in an induction heating device according to one embodiment.

[0153] Referring to Fig. 8, the horizontal axis may represent time, and the vertical axis may represent vibration intensity. The horizontal axis shows sections for the initial heating control step (400), the correction data acquisition step (402), the container heating detection step (404), the maximum slope detection step (406), the boiling candidate detection step (408), the power level reduction and maintenance step (410), the boiling confirmation step (412), and the boiling control step (414), respectively.

[0154] During the series of processes in which water boils, the data received from the vibration sensor (140) may appear unbalanced and unstable.

[0155] The thin lines in the graph represent the vibration intensity calculated at that point.

[0156] The bold line in the graph represents the vibration intensity stabilized through a series of algorithms. This value is defined as the reference value for vibration intensity.

[0157] A reference value for vibration intensity can be calculated by combining the moving average and the moving median.

[0158] As described above, assuming that FFT is performed once every 250 ms, the reference value of vibration intensity is calculated using the FFT results as follows.

[0159] First, the sum of the vibration intensities of each frequency band that is not ignored in the correction data acquisition step (402) can be obtained. This value is called P. This P can correspond to a single point included in a thin line in the graph.

[0160] Afterwards, the P values ​​over a recent period of time (e.g., 5 seconds) can be sorted. For example, 20 data points can be sorted based on a 250ms period.

[0161] The average of the medians over a given period of time (e.g., 3 seconds) can be calculated. This value can serve as a reference value. For example, the average of 12 medians over a 250ms period can be calculated.

[0162] In summary, rather than selecting a single median, a range of values ​​can be selected and the average of these values ​​can be taken. By taking the average of partial medians, a stable vibration intensity can be obtained while ignoring intermittent noise.

[0163] Referring again to Figure 7, a method for calculating the slope of the vibration intensity is described.

[0164] The slope of the vibration intensity is constantly computed throughout the water boiling detection algorithm and is one of the comparison targets for step transitions.

[0165] This slope can represent the slope value of the thick line in the graph shown in Fig. 8.

[0166] The mathematical meaning of slope is as follows: a positive slope indicates an upward slope, while a negative slope indicates a downward slope. A positive slope indicates a steeper rise with a larger value. A negative slope indicates a steeper decline with a smaller value. Therefore, the sign or value of the slope can be used to determine the trend of a graph.

[0167] Because the data received from the vibration sensor (140) is unstable, the slope can also be calculated over a period of time. A longer calculation time can more accurately reflect the state, but may also slow down the response time. This means that even if the water has boiled, the response time to "boil" will be delayed. A shorter calculation time can reflect the state more in real time, but may also reduce accuracy. A response to "boiling" may occur when the water is not.

[0168] A thick line, for example, can be used to plot points at 250ms intervals. By gathering a certain number of recent data points, the average slope can be calculated. For example, if the time interval is set to 5 seconds, a single straight line representing the most recent 20 points can be drawn, and the slope of this line can be used as the output.

[0169] The intervals can be set differently depending on the algorithm step. The slope calculation intervals for each step are as follows.

[0170] For example, the container heating detection step (404), the maximum slope detection step (406), the power level reduction and maintenance step (410), etc. can calculate the slope based on 5 seconds.

[0171] The boiling candidate detection step (408) can calculate the slope based on 3 seconds.

[0172] The boiling candidate detection step (408) is a process for finding a candidate rather than confirming that the water is boiling, so it must be found as quickly as possible. If a candidate for boiling is selected, a process of temporarily lowering the power level may be performed in the next step. Shortening this time allows for a quicker response to boiling over water. However, because the accuracy of the state determination is low, the power level lowering step may be entered even before the water has boiled, which may take longer to ultimately detect boiling water. On the other hand, lengthening this time may delay the response to boiling over water. However, because the accuracy of the state determination is high, the power level lowering step may not be entered, which may ultimately shorten the time until the water boils.

[0173] The boiling confirmation step (412) can calculate the slope based on 25 seconds.

[0174] The boiling confirmation step (412) determines whether the water has definitely boiled, so it requires a sufficiently long stabilization time to calculate the slope. Shortening this time can reduce the accuracy of boiling judgments, as the stabilization time is shortened. This can lead to the power level being set too high when the water is already boiling, or the water being judged to have boiled before it has actually boiled. Increasing this time also lengthens the stabilization time, which can prolong the time it takes to confirm a boil, even if the water has actually boiled.

[0175] Below, the container heating detection step (404) is described in detail.

[0176] In the container heating detection step (404), the power level is set to 9, so the water contained in the cooking container (10) can be heated at power level 9.

[0177] To detect that the cooking vessel (10) has become hot and water has started to evaporate, it can be determined whether the vibration intensity is above the vessel heating detection threshold.

[0178] The container heating detection threshold can be obtained by the following equation [1].

[0179] Container heating detection threshold = {number of valid frequency bands} × {average intensity of valid frequency bands} × {container heating detection coefficient} - Equation [1]

[0180] The number of valid frequency bands may be the number of bands excluding the ignored frequency bands described in the correction data acquisition step (402) among all frequency ranges. In other words, it may be the number of bands that are not ignored among all frequency ranges.

[0181] The intensity average of a valid frequency band may be the average of the intensities of the non-ignored frequency bands described in the correction data acquisition step.

[0182] The container heating detection coefficient is a preset coefficient.

[0183] If the control unit (150) satisfies the container heating detection condition for a certain period of time, it determines that heating of the cooking container (10) has been detected and can move on to the next step, the maximum slope detection step (406) (①).

[0184] You can check whether the following three conditions are satisfied.

[0185] Condition 1) 1 < {Vibration intensity slope}

[0186] Condition 2) {Container heating detection threshold} < {Vibration intensity reference value}

[0187] Condition 3) Conditions 1) and 2) are satisfied continuously during the detection time.

[0188] Condition 1 may mean that the graph has an upward slope.

[0189] Condition 2 may mean that the vibration intensity is above a certain level compared to the correction point.

[0190] For example, if the detection time is set to 5 seconds, the detection conditions must be met continuously for 5 seconds. Since the check cycle is 250ms, this would be 20 consecutive times. If even one condition is not met, the count can be reset.

[0191] By shortening the detection time, it can be recognized that the cooking vessel (10) is heated even when it is not actually heated. By lengthening the detection time, if the amount of water is considerably small, it can remain in this stage even when the water is almost completely boiled.

[0192] In order to improve the accuracy of the container heating detection step (404), first, the efficiency of the cooking container (10) can be applied to the container heating detection threshold. That is, a coefficient proportional to the efficiency of the cooking container (10) can be applied.

[0193] Additionally, to improve the accuracy of the container heating detection step (404), a probabilistic approach can be adopted by varying the intervals for calculating the reference value and slope. For example, the reference value (slope) can be calculated in various intervals of 1 second / 3 seconds / 5 seconds / 7 seconds / 9 seconds, and the one with the most votes can be used to determine a specific situation.

[0194] Meanwhile, in the container heating detection step (404), it can be confirmed whether an exception is detected.

[0195] In the vessel heating detection step (404), there may be cases where water that has just recently boiled is being heated. In this case, since the cooking vessel (10) has already been heated for a short time and the water is above 90 degrees, it will boil immediately when the power level is set to 9.

[0196] Since this is not a normal situation, the water must be heated and an exception must be filtered out at the first entering vessel heating detection step (404).

[0197] If the conditions below are satisfied for a certain period of time in the container heating detection step (404), it is determined that the water is already boiling and the process can proceed to the boiling control step (414) (②).

[0198] Condition 1) 1 > {Vibration intensity slope}

[0199] Condition 2) {Container heating detection threshold} < {Vibration intensity reference value}

[0200] Condition 3) The above conditions must be met for 3 consecutive seconds.

[0201] Condition 1 can mean that the slope is downward or that the status quo is maintained.

[0202] Condition 2 may mean that the vibration intensity is above a certain level compared to the correction point.

[0203] To summarize the above conditions, it could mean that the vibration is strong but does not become stronger or rather becomes weaker.

[0204] Below, the maximum slope detection step (406) is described.

[0205] The maximum tilt detection step (406) is a step that is entered when it is confirmed in the container heating detection step (404) that the cooking container (10) is heated.

[0206] In the maximum slope detection step (406), a high power level can be maintained. The power level can be set to 9.

[0207] As water heats, the increase in vibration intensity can gradually increase. However, at some point, the increase slows down, and this point can be identified. This value can be used for verification because it is related to the slope of the vibration intensity graph.

[0208] The maximum slope detection step (406) may be a step for checking whether the minimum condition that can determine whether water is boiling is satisfied.

[0209] The maximum slope detection step (406) simply estimates whether water is boiling based on the slope, but may not guarantee that the slope is at its peak during the boiling process. This estimation step may be performed to improve the accuracy and reliability of the algorithm, as a pattern of temporary slope reduction frequently occurs depending on the type of cooking vessel (10) and the physical flow of water.

[0210] The maximum slope detection step (406) may be a step for checking the state just before water boils when dividing the series of processes of boiling water into several steps.

[0211] FIG. 9 is a graph showing an example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0212] Referring to Figure 9, the horizontal axis represents time and the vertical axis represents vibration intensity.

[0213] A graph of the vibration intensity over time is roughly shown when an appropriate amount of water is put into an ideal cooking container (10) and boiled.

[0214] As water heats, the rate of increase in vibration intensity becomes steeper. In other words, the slope of the vibration intensity increases. After a certain amount of heating, the rate of increase in vibration intensity gradually decreases and the vibration intensity reaches a peak. In other words, the slope gradually decreases until it reaches zero.

[0215] In summary, the following criteria can be established: The slope is calculated periodically and updated whenever the maximum slope value is updated. After a certain amount of time (e.g., 5 seconds) has elapsed since the last update of the maximum slope value, the next step, the boiling candidate detection step (408), can be moved on (③).

[0216] If the above criteria are satisfied, then it is considered a stage where boiling can be confirmed and the next stage, boiling candidate detection stage (408), can be moved on.

[0217] However, there are practical limitations. In reality, some containers exhibit unusual vibration patterns when boiling water, and the amount of water can vary.

[0218] FIG. 10 is a graph showing another example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0219] Referring to Figure 10, a realistic graph is shown that deviates from the criteria for the maximum slope described above.

[0220] In the maximum slope detection step (406), if the slope alone is used, the water may be judged to be sufficiently heated at a point (t1) when it is not yet sufficiently heated, and the next step may be moved on. This is because the vibration intensity does not increase uniformly, and will increase again over time.

[0221] Generally, if you graph and analyze the series of processes that lead to the boiling of water, the point where the vibration intensity reaches its peak is the point where the water begins to boil.

[0222] FIG. 11 is a graph showing another example of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0223] Referring to Figure 11, we've identified a point likely to be a short-term peak through the maximum slope, but it's difficult to discern whether this is the actual boiling point or a temporary decline. This is because it's difficult to guarantee that the graph won't appear as the dotted line's oscillation intensity. It's also difficult to guarantee that the graph won't be completed.

[0224] Since the graph above is drawn all the way to the future, it can be seen that the result is the vibration intensity of the solid line, but in the process of drawing the graph in real time, it is not easy to judge because the graph may be completed like the vibration intensity of the dotted line depending on the type of cooking vessel (10) or the amount of water.

[0225] If you judge the peak of the vibration intensity too quickly, you may be vulnerable to the dotted line and the temporary decline in the vibration intensity. However, if you judge the peak of the vibration intensity too slowly, you may risk leaving the water boiling for too long.

[0226] Although it is difficult to quickly and accurately determine the peak point of vibration intensity based on the maximum slope value in the maximum slope detection step (406), the accuracy can be improved by compensating for realistic constraints.

[0227] Since the accuracy of judging the maximum value of the slope is low in reality, it can be supplemented by adding the maximum value of the vibration intensity as a condition.

[0228] As the water heats up, the vibration intensity increases, so the vibration intensity also continues to increase.

[0229] The peak of the vibration intensity is updated more frequently than the peak of the slope is updated.

[0230] Therefore, the condition can be supplemented by adding an update to the maximum value of the vibration intensity.

[0231] The vibration intensity is calculated periodically and updated whenever the maximum vibration intensity value is updated. After a certain amount of time (e.g., 4 seconds) has elapsed from the time the maximum vibration intensity value was last updated, the process can proceed to the next step, the boiling candidate detection step (408).

[0232] Adding this condition increases the success rate of the judgment at the maximum slope detection step (406), but considering that the water begins to boil at the highest point, there may be concerns that the water may remain boiling for a long time. This is because even if the water boils, the point at which the power level is lowered is delayed.

[0233] To compensate for this situation, the elapsed time can be adjusted. As mentioned above, the time condition for calculating the slope was the reference time (e.g., 5 seconds) based on the last update time, but in this step, the response speed can be improved by shortening the reference time (e.g., 4 seconds).

[0234] Additionally, verification logic can be added to the next step, the boiling candidate detection step (408), to allow for a return to the maximum slope detection step (406) (④). Logic can be added to allow for a return to the next step, assuming that the results determined in the maximum slope detection step (406) are inaccurate.

[0235] In summary, by synthesizing the theoretical background and supplementary matters, in the maximum slope detection step (406), the slope is periodically calculated, and whenever the maximum slope value is updated, the remaining time can be updated to, for example, 5 seconds. The vibration intensity can be periodically calculated, and whenever the maximum vibration intensity value is updated, if the remaining time is less than 4 seconds (less than 5 seconds), it can be updated to 4 seconds. The remaining time decreases over time, and when it becomes 0, the process can proceed to the next step (boiling candidate detection step (408)).

[0236] Meanwhile, in the maximum slope detection step (406), exceptions can be detected.

[0237] Assuming that the cooking vessel (10) is sufficiently heated, the maximum tilt detection step (406) is entered.

[0238] However, experimentally, an exceptional case may occur in which entry occurs even in situations where this is not the case, depending on the type of cooking container (10).

[0239] Usually, at the beginning of boiling water, the cooking vessel (10) may vibrate loudly on its own and then suddenly become quiet.

[0240] To handle such exceptions, it is also possible to check whether the cooking vessel (10) is not heated during the maximum tilt detection step (406).

[0241] If it is determined that the cooking container (10) is not heated, the process can return to the previous step, the container heating detection step (404) (⑤).

[0242] The criteria for determining exceptions are as follows:

[0243] {Container heating detection threshold} > {Vibration intensity reference value}

[0244] Once the above conditions are met, the process can return to the previous step (container heating detection step (404)). Since it has been determined that the current step was entered incorrectly, all maximum values ​​calculated in this step can be initialized.

[0245] Below, the boiling candidate detection step (408) is described.

[0246] When the vessel is sufficiently heated and the graph is expected to reach a maximum soon, the boiling candidate detection step (408) can be entered. The maximum may include a short-term peak followed by a decline.

[0247] In the boiling candidate detection step (408), a high power level can be maintained. The power level can be set to 9.

[0248] As water boils, the vibration intensity gradually weakens. This characteristic can be used to determine whether the water has boiled. This can be determined by the slope of the vibration intensity graph falling below a certain level.

[0249] The boiling candidate detection step (408) can largely perform the tasks of determining realistic constraints, detecting maximum values, and detecting exceptions.

[0250] First, we explain how to determine realistic constraints in the boiling candidate detection step (408).

[0251] The induction heating device (1) cannot know what cooking vessel the user is using or how much water is added. Therefore, even if a phase transition occurs, it cannot be confirmed that it occurred as intended. It is assumed to have occurred correctly, and the intended result may differ from the actual result.

[0252] If a maximum value is detected in the boiling candidate detection step (408), the next step can be moved to the power level reduction and maintenance step (410) (⑥).

[0253] However, even if we find a local maximum, it may not guarantee that it is the highest point in the series of steps that boil water.

[0254] Fig. 12 is a graph showing the maximum value of vibration intensity over time when boiling food contained in a cooking container in an induction heating device according to one embodiment.

[0255] Referring to Figure 12, the vibration intensity may not appear as a solid line, but as a dotted line in the middle.

[0256] Even if we proceed to the next stage, it doesn't guarantee that the water has boiled, which is why we've included candidate stage names. This estimate will be finalized after a stabilization phase, which will be discussed later.

[0257] The detection of the maximum value in the boiling candidate detection step (408) is described.

[0258] Mathematically, as the time value increases, the positive slope gradually decreases and becomes negative, and the value at the point where the slope is 0 is called a local maximum.

[0259] FIG. 13 is a graph showing an example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0260] Referring to Figure 13, the maximum value can be confirmed in the graph of vibration intensity.

[0261] This can be easily found by checking the point where the slope of the vibration intensity becomes 0.

[0262] However, the process of boiling water does not always produce an ideal graph shape.

[0263] FIG. 14 is a graph showing another example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0264] Referring to Figure 14, it can be seen that sections with a slope of 0 frequently occur.

[0265] As mentioned above, the slope is not calculated based on a specific point in time. It includes data up to a few seconds prior to the present and calculates a straight line representing these points. Therefore, even if the vibration intensity declines slightly, if it begins to rise again, it can be filtered to a certain extent.

[0266] However, we know experimentally that if water actually boils, the slope drops significantly.

[0267] FIG. 15 is a graph showing another example of detecting the maximum value of vibration intensity over time when boiling water in a cooking vessel in an induction heating device according to one embodiment.

[0268] Referring to Figure 15, accuracy can be further improved by setting the slope judgment criterion to some negative number less than 0 rather than 0.

[0269] As long as the noise level is not as high as that of boiling water, it can be filtered to a certain level. The smaller this negative number, the greater the noise resistance, but it may take longer to detect boiling, or it may not even be detected.

[0270] Therefore, determining the value of this slope is crucial. Setting it to a specific negative value can make it difficult to guarantee correct operation across various patterns. A more effective approach is to consider the values ​​calculated in the previous steps, which influence the drop, as much as possible.

[0271] Accordingly, the slope drop detection threshold, which serves as the standard for slope drop detection, can be obtained by the following equation [2].

[0272] Slope drop detection threshold = {maximum slope} × {number of valid frequency bands} × {slope drop detection coefficient} - Equation [2]

[0273] The maximum slope value may be the maximum slope value calculated in the maximum slope detection step (406). If the vibration intensity rises steeply, it can be expected to fall more steeply.

[0274] The number of valid frequency bands may be the number of non-ignored frequency bands.

[0275] The vibration intensity graph is the sum of the vibration intensity in each frequency range over time.

[0276] The more areas are ignored, the more we can expect a relatively gentle decline.

[0277] The slope drop detection coefficient is a preset coefficient.

[0278] The conditions for detecting the final maximum are as follows:

[0279] {slope} < {slope drop detection threshold}

[0280] If the above conditions are satisfied a preset number of times (for example, once), the next step, power level reduction and maintenance step (410), can be moved on (⑥).

[0281] Meanwhile, the detection of the first exception in the boiling candidate detection step (408) is described.

[0282] Apart from detecting the inflection point, the same algorithm as performed in the maximum slope detection step (406) can be performed as follows. If the slope is calculated and is greater than the maximum slope value, the process can return to the previous step, the maximum slope detection step (406) (④). If the vibration intensity is calculated and is greater than the maximum vibration intensity value, the process can return to the previous step (the maximum slope detection step (406)) (④). The two maximum values ​​referred to here may be the maximum values ​​calculated in the previous step. This indicates a case where a sharp rise pattern appears before finding the inflection point or a case where the vibration intensity peak is updated.

[0283] Additionally, it describes detecting a second exception in the boiling candidate detection step (408).

[0284] After going through several stages, there are cases where the water reaches a boiling point and then enters this stage.

[0285] In this case, the vibration intensity does not decrease abruptly because the water is already boiling. This means that the maximum value may not be detected. Furthermore, it may not be detected by the first exception detection method described above. At this stage, an exception can be added to detect whether the water is exhibiting a boiling pattern. For reference, it has been experimentally confirmed that after the water boils and sufficient stabilization time has elapsed, the slope converges to zero or decreases gradually.

[0286] If the following conditions are met, it can be determined that the second exception has been detected.

[0287] {Slope} < {Slope at which water boils}

[0288] The above conditions must be met for 10 consecutive seconds.

[0289] Here, the water boiling confirmation slope can be a preset value.

[0290] If a second exception is detected in the boiling candidate detection step (408), the process can move to the boiling confirmation step (412) (⑦).

[0291] Below, the power level reduction and maintenance step (410) is described.

[0292] If a situation occurs where the water is presumed to have boiled, the power level can be reduced and maintained (410) (⑥).

[0293] In the power level reduction and maintenance step (410), the power level can be reduced and a stabilization time can be provided. The power level can be set to 7.

[0294] This is to lower the power level and watch, as the water may not have boiled. If the water has boiled, you can lower the power level and watch, as it will boil too vigorously.

[0295] And in the next step, the boiling confirmation step (412), data to be used for calculation can be secured.

[0296] In the power level reduction and maintenance step (410), changing the power level to a lower value will result in an overall decrease in vibration intensity. This may require a stabilization time.

[0297] In addition to stabilizing the physical flow of water contained in the cooking vessel (10), it is necessary to stabilize the baseline value and slope of the vibration intensity. This is because these values ​​are calculated based on data from several seconds in the past relative to the current point in time. For example, the holding time for stabilization may be 15 seconds.

[0298] The power level reduction and maintenance step (410) can calculate the minimum vibration intensity reference value from the time of entry into this step. This can be used to confirm boiling of water in the next step, the boiling confirmation step (412).

[0299] After the power level is lowered in the power level reduction and maintenance step (410) and the maintenance time has elapsed, the process can proceed to the boiling confirmation step (412) (⑧).

[0300] Meanwhile, in the power level reduction and maintenance phase (410), exceptions can be detected.

[0301] Entering this stage can be assumed to mean that the water is sufficiently heated. This may include ensuring that the vibration intensity does not fall below a specified level.

[0302] Since the vibration intensity pattern varies, there is a low probability that this stage may occur early in the boiling process. This may be due to the cooking vessel (10) vibrating loudly at the beginning of the boiling process and then suddenly becoming quiet.

[0303] To handle such exceptions, this step may also include checking that the cooking vessel (10) is not heated.

[0304] If it is determined that the cooking vessel (10) is not heated, the process can return to the vessel heating detection step (404) (⑨).

[0305] The criteria for judging this are as follows:

[0306] {Container heating detection threshold} > {Vibration intensity reference value}

[0307] If the above conditions are satisfied, the process can return to the container heating detection step (404) (⑨).

[0308] Since we have determined that we have entered the current stage incorrectly, we can initialize most of the data except for the correction results.

[0309] Below, the boiling confirmation step (412) is described.

[0310] In the boiling confirmation stage (412), the power level can be maintained at 7.

[0311] Experimentally, we've confirmed that once the boiling process is sufficiently stabilized, the vibration intensity either maintains its current level or gradually declines. This can be true when the slope is below 0. However, the decline isn't unconditional; it persists within a certain range. Therefore, while the slope can exceed 0, it's still a low value compared to the boiling process and doesn't deviate significantly from 0.

[0312] This step can be entered even when the water is not yet boiling, in which case an upward-sloping graph is drawn. In this case, the process can return to the vessel heating detection step (404) (⑪) or the maximum slope detection step (406) (⑫).

[0313] The boiling confirmation step (412) can perform the following: immediate detection of water boiling, final detection of water boiling over a sufficient period of time, and detection of exceptions.

[0314] First, we describe the immediate detection of water boiling in the boiling confirmation step (412).

[0315] When certain conditions are met, it can be immediately determined that the water has boiled.

[0316] We can take advantage of the fact that the vibration intensity gradually decreases when water boils. If the water had not boiled, it would either remain at its current level or trend upward.

[0317] In the previous step, the power level reduction and maintenance step (410), sufficient stabilization time was provided, and the lowest point of the vibration intensity was also calculated.

[0318] In the boiling confirmation step (412), it can be immediately determined that boiling of water has been successfully detected when the following conditions are satisfied.

[0319] {Vibration intensity} < {Minimum vibration intensity}

[0320] If the above conditions are met, it can be determined that boiling water has been detected immediately.

[0321] Additionally, it describes the final detection of water boiling over a sufficient period of time in the boiling confirmation step (412).

[0322] After sufficient time, the boiling of water is finally determined. For example, after entering this stage, a final determination can be made after 25 seconds. This may be the logic for making a final determination in a situation where no detection is made in other parts of this stage. If the time interval for calculating the slope of the vibration intensity in the container heating detection stage (404) is set to 25 seconds, a final determination is made 25 seconds after entering this stage. This is to check the slope of the representative straight line for all vibration intensities that occurred during this time. Based on this slope value, the boiling of water can be finally determined and the process can proceed to the boiling control stage (414). Otherwise, the process can return to the heating detection stage (404) (⑪) or the maximum slope detection stage (406) (⑫).

[0323] If the following conditions are met, we can consider that boiling water has been successfully detected.

[0324] {Slope} < {Water boiling stabilization slope}

[0325] For example, the slope can represent the average trend of vibration intensity over 25 seconds.

[0326] The water boiling stabilization slope is a preset coefficient.

[0327] If the above conditions are not satisfied, the process can return to the maximum slope detection step (406) (⑫).

[0328] Meanwhile, it describes detecting exceptions in the boiling confirmation step (412).

[0329] This is the case when the water has not yet boiled.

[0330] If the cooking vessel (10) is heated to a certain degree, the vibration intensity increases, so an upward graph is drawn. By referring to the maximum slope value calculated in the maximum slope detection step (406), it can be confirmed whether the upward slope criterion is satisfied. The reason for referring to this is because the power level in the current step, the boiling confirmation step (412), is 7, and the power level of the maximum slope detection step (406) is 9. In other words, since the slope was obtained based on the power level 9, a correction to make the slope gentle may be required.

[0331] The slope correction value can be obtained by the following equation [3].

[0332] Slope correction value = {maximum slope value} × {number of valid frequency bands} × {slope correction factor} - Equation [3]

[0333] The maximum slope value may be the maximum slope value calculated in the previous maximum slope detection step (406).

[0334] The number of valid frequency bands may be the number of non-ignored frequency bands.

[0335] The more areas are ignored, the more we can expect a relatively gradual increase.

[0336] The slope correction coefficient can be a preset coefficient.

[0337] If the following conditions are satisfied based on the slope compensation value, it can immediately transition to the maximum slope detection step (406) (⑫).

[0338] {slope} > {slope correction value}

[0339] If this condition is met, it may mean that there is an upward trend.

[0340] Below, the boiling control step (414) is described.

[0341] You can enter this step if you successfully detect that the water has boiled.

[0342] In the boiling control step (414), the power level can be lowered. The power level can be set to 5.

[0343] Additionally, in the boiling control step (414), the control unit (150) can display the boiling state and / or boiling progress of the water contained in the cooking vessel (10) through the display (120) so that the user can check the boiling information of the water.

[0344] According to the present disclosure, boiling of food contained in a cooking vessel can be detected more accurately and reliably, regardless of the type of cooking vessel.

[0345] An induction heating device according to one embodiment of the present disclosure may include: a plate on which a cooking vessel is positioned; a vibration sensor for detecting vibration of the cooking vessel; a heating coil for heating the cooking vessel; and a control unit for increasing a power level of the heating coil so that food contained in the cooking vessel is heated, obtaining a first vibration pattern of the cooking vessel based on vibration data of the vibration sensor, and decreasing the power level of the heating coil and maintaining the first vibration pattern for a predetermined period of time when the first vibration pattern satisfies a first condition, obtaining a second vibration pattern of the cooking vessel after the predetermined period of time has elapsed, and determining that the food is in a boiling state based on the second vibration pattern satisfying the second condition.

[0346] The control unit can obtain correction data excluding a vibration component generated by at least one of an inverter and a cooling fan of the induction heating device from among the vibration data of the vibration sensor, and determine a vibration intensity and a vibration intensity slope based on the correction data.

[0347] The above-described first condition may include at least one of a condition in which the slope of the vibration intensity of the first vibration pattern is maximum and a condition in which the maximum value of the vibration intensity is detected.

[0348] The condition in which the slope of the vibration intensity of the first vibration pattern is maximum can be determined based on the maximum value of the slope of the vibration intensity and the maximum value of the vibration intensity.

[0349] The condition in which the maximum value of the vibration intensity is detected may include a condition in which the slope of the vibration intensity is less than a slope drop detection threshold.

[0350] The above-described first condition may include a container heating detection condition determined based on the slope of the vibration intensity and the container heating detection threshold.

[0351] The second predetermined condition may include a condition in which the vibration intensity of the second vibration pattern is maintained or decreased.

[0352] The second predetermined condition may include that the vibration intensity of the second vibration pattern is less than the minimum value of the vibration intensities while reducing the power level of the heating coil and maintaining it for a predetermined time.

[0353] The second predetermined condition may include a condition in which the slope of the vibration intensity of the second vibration pattern is less than a preset slope.

[0354] The above cooking agent may be water.

[0355] The display may further include a control unit that can control the display to display at least one of a boiling state and a boiling progress rate of the food contained in the cooking vessel.

[0356] A control method of an induction heating device according to one embodiment of the present disclosure includes a control method of an induction heating device including a vibration sensor for detecting vibration of a cooking vessel positioned on a plate, and a heating coil for heating the cooking vessel, the control method comprising: increasing a power level of the heating coil so that food contained in the cooking vessel is heated; acquiring a first vibration pattern of the cooking vessel based on vibration data of the vibration sensor; reducing the power level of the heating coil and maintaining the power level for a predetermined period of time when the first vibration pattern satisfies a predetermined first condition; acquiring a second vibration pattern of the cooking vessel after the predetermined period of time has elapsed; and determining that the food is in a boiling state based on the second vibration pattern satisfying a predetermined second condition.

[0357] The method may further include obtaining correction data excluding a vibration component generated in at least one of an inverter and a cooling fan of the induction heating device from among the vibration data of the vibration sensor, and determining a vibration intensity and a vibration intensity slope based on the correction data.

[0358] The above-described first condition may include at least one of a condition in which the slope of the vibration intensity of the first vibration pattern is maximum and a condition in which the maximum value of the vibration intensity is detected.

[0359] The condition that the slope of the vibration intensity of the first vibration pattern is maximum may include being determined based on the maximum slope of the vibration intensity and the maximum value of the vibration intensity.

[0360] The condition in which the maximum value of the vibration intensity is detected may include a condition in which the slope of the vibration intensity is less than a slope drop detection threshold.

[0361] The above-described first condition may further include a container heating detection condition determined based on the slope of the vibration intensity and the container heating detection threshold value.

[0362] The second predetermined condition may include a condition in which the vibration intensity of the second vibration pattern is maintained or decreased.

[0363] The second predetermined condition may include at least one of a condition in which the vibration intensity of the second vibration pattern is less than the minimum value of the vibration intensities while reducing the power level of the heating coil and maintaining it for a predetermined period of time, and a condition in which the slope of the vibration intensity of the second vibration pattern is less than a preset slope.

[0364] The method may further include controlling the display to display at least one of the boiling state and boiling progress of the food contained in the cooking vessel.

[0365] Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments.

[0366] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory storage medium" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored in the storage medium and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0367] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0368] The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present invention can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. Plate on which the cooking container is positioned; A vibration sensor for detecting vibration of the above cooking container; a heating coil for heating the cooking vessel; and Increase the power level of the heating coil so that the food contained in the cooking container is heated, Obtaining a first vibration pattern of the cooking vessel based on the vibration data of the vibration sensor, When the first vibration pattern satisfies a predetermined first condition, the power level of the heating coil is reduced and maintained for a predetermined time, After the above-mentioned predetermined time has elapsed, the second vibration pattern of the cooking vessel is obtained, An induction heating device including a control unit that determines that the food is in a boiling state based on the second vibration pattern satisfying a predetermined second condition.

2. In paragraph 1, The above control unit, An induction heating device that obtains correction data excluding a vibration component generated in at least one of an inverter and a cooling fan of the induction heating device from the vibration data of the vibration sensor, and determines the vibration intensity and the vibration intensity slope based on the correction data.

3. In paragraph 1, The above first condition is, An induction heating device comprising at least one of a condition in which the slope of the vibration intensity of the first vibration pattern is maximum and a condition in which a maximum value of the vibration intensity is detected.

4. In paragraph 3, The condition for the maximum slope of the vibration intensity of the first vibration pattern is: An induction heating device determined based on the maximum slope of the vibration intensity and the maximum value of the vibration intensity.

5. In paragraph 3, The conditions under which the maximum value of the vibration intensity is detected are: An induction heating device including a condition in which the slope of the vibration intensity is less than a slope drop detection threshold.

6. In paragraph 3, The above first condition is, An induction heating device comprising a vessel heating detection condition determined based on a slope of the vibration intensity and a vessel heating detection threshold value.

7. In paragraph 1, The second condition stipulated above is, An induction heating device including a condition in which the vibration intensity of the second vibration pattern is maintained or decreased.

8. In paragraph 1, The second condition stipulated above is, An induction heating device comprising a vibration intensity of the second vibration pattern that is less than the minimum value of the vibration intensities while reducing the power level of the heating coil and maintaining it for a predetermined period of time.

9. In paragraph 1, The second condition stipulated above is, An induction heating device including a condition in which the slope of the vibration intensity of the second vibration pattern is less than a preset slope.

10. In paragraph 1, The above cooking material is an induction heating device with water.

11. In paragraph 1, Including more displays, An induction heating device wherein the control unit controls the display to display at least one of the boiling state and boiling progress of the food contained in the cooking container.

12. A method for controlling an induction heating device including a vibration sensor for detecting vibration of a cooking vessel positioned on a plate and a heating coil for heating the cooking vessel, Increase the power level of the heating coil so that the food contained in the cooking container is heated; Obtaining a first vibration pattern of the cooking vessel based on the vibration data of the vibration sensor; When the first vibration pattern satisfies a predetermined first condition, the power level of the heating coil is reduced and maintained for a predetermined time; After the above-mentioned predetermined time has elapsed, a second vibration pattern of the cooking vessel is obtained; A control method for an induction heating device, comprising: determining that the food is in a boiling state based on the second vibration pattern satisfying a predetermined second condition.

13. In paragraph 12, A control method for an induction heating device further comprising: obtaining correction data excluding a vibration component generated in at least one of an inverter and a cooling fan of the induction heating device from the vibration data of the vibration sensor, and determining a vibration intensity and a vibration intensity slope based on the correction data.

14. In paragraph 12, The above first condition is, A control method for an induction heating device including at least one of a condition in which the slope of the vibration intensity of the first vibration pattern is maximum and a condition in which a maximum value of the vibration intensity is detected.

15. In paragraph 14, The condition for the maximum slope of the vibration intensity of the first vibration pattern is: A control method for an induction heating device, comprising determining based on the maximum slope of the vibration intensity and the maximum value of the vibration intensity.

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