Home appliance

Abstract

Disclosed is a home appliance for protecting an inverter circuit by monitoring a frequency operation region of the inverter circuit. The home appliance determines a capacitive region by measuring a phase difference between a switching voltage and a resonance current of the inverter circuit, and sets an operation of the inverter circuit if a frequency operation region of the inverter circuit is determined to be the capacitive region more than a predetermined number of times, thereby restricting an operation of the inverter circuit in the capacitive region.

Description

home appliances

[0001] The present invention relates to a home appliance, and more particularly, to a home appliance including an induction heating cooktop.

[0002]

[0003] Induction ranges, which utilize induction heating technology, are gaining attention as next-generation cooking appliances that can replace gas ranges due to their advantages such as high heating efficiency, fast heating speed, stability, and convenience.

[0004] Induction heating cooktops feature heating coils made of Ritz wire. These cooktops heat induction-specific containers by placing them on a designated burner. This method requires containers to be placed in a specific location, and any slight misalignment reduces heating efficiency.

[0005] Accordingly, research and development are underway for "All Free" induction heating technology. This technology enables heating of induction containers in various locations without requiring a fixed area on the induction heating plate. It also offers the advantage of being able to heat containers of various sizes and multiple containers with three or more zones.

[0006] In an induction heating system, the inverter is configured as a resonant inverter to generate electromagnetic force to generate eddy currents for heating the vessel. The operating frequency range of an induction heating system, including a resonant network composed of a heating coil and a resonant capacitor, can be broadly divided into an inductive operating region and a capacitive operating region based on the resonant frequency. The induction heating system is primarily driven by frequency driving in the inductive region.

[0007] If operation is performed in the capacitive region, the switching element may be thermally destroyed or the operating time may be shortened due to increased power loss in the switching element, so operation in the capacitive region should be limited as much as possible.

[0008] Prior art 1 (US 9596721 B2) detects the operating range based on the comparison voltage and adjusts the operating frequency. However, prior art 1 has a high potential for errors due to the magnitude of the resonant current. For example, during high-output operation of a weakly magnetic container, the output voltage may be higher than the comparison voltage, resulting in an error that determines the resonant frequency to be below the resonant frequency.

[0009]

[0010] The present invention provides an electrical appliance that monitors the frequency operating range of an inverter circuit in an induction heating system and protects it from being driven in a capacitive range.

[0011] The present invention provides a home appliance that detects a capacitive region by measuring a phase difference between a switching voltage and a resonant current of an inverter circuit and limits operation in the capacitive region.

[0012] The present invention provides a home appliance capable of preventing an increase in loss in a switching element of an inverter circuit by satisfying ZVS (Zero Voltage Switching) operation.

[0013] The present invention provides a home appliance capable of determining a frequency operating range regardless of operating conditions such as container type, container coupling state, and input voltage by comparing the switching point of an inverter circuit and the point of resonance current.

[0014] The present invention provides a home appliance capable of protecting the system by initializing an inverter circuit when the frequency operating range of an induction heating system is a capacitive range.

[0015] The problems to be solved according to one embodiment of this specification are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0016]

[0017] A home appliance according to one embodiment of the present invention monitors a frequency operating range of an inverter circuit to protect the inverter circuit from being driven in a capacitive range.

[0018] Specifically, the home appliance determines the frequency operating range of the inverter circuit, and if the judgment result is determined to be a capacitive range a certain number of times or more, performs the operation setting of the inverter circuit.

[0019] A home appliance according to one embodiment of the present invention detects a capacitive region by measuring a phase difference between a switching voltage and a resonant current of an inverter circuit and restricts operation in the capacitive region.

[0020] Specifically, the appliance compares the voltage corresponding to the resonant current with the reference voltage and determines the frequency operating range of the inverter circuit based on the pulse signal resulting from the comparison. If the appliance determines that the circuit is in the capacitive range a certain number of times or more, it initializes the inverter circuit and switches the inverter circuit at the switching frequency immediately before the capacitive range.

[0021] A home appliance according to one embodiment of the present invention satisfies ZVS (Zero Voltage Switching) operation, thereby preventing an increase in loss in a switching element of an inverter circuit.

[0022] Specifically, when the frequency operating range of the inverter circuit is determined to be a capacitive range for a certain number of times or more, the home appliance adjusts the switching frequency for driving the inverter circuit to change the frequency operating range to an inductive range.

[0023] A home appliance according to one embodiment of the present invention determines a frequency operating range regardless of operating conditions such as container type, container coupling state, and input voltage.

[0024] Specifically, the home appliance generates a pulse signal by comparing the switching point of the inverter circuit with the point of resonance current, generates a trigger signal in synchronization with the falling edge of the pulse signal, and determines the frequency operation range by using the elapsed time from the start point of the switching frequency count of the inverter circuit to the point at which the trigger signal is generated.

[0025] An appliance according to one embodiment of the present invention protects the system when the frequency operating range of the induction heating system is a capacitive range.

[0026] Specifically, the appliance performs an operation setting of the inverter circuit, including at least one of: initializing the inverter circuit when the frequency operating range is a capacitive range; switching and driving the inverter circuit at a switching frequency immediately before the capacitive range; and alarming the user with a preset message. In addition, the appliance adjusts the switching frequency to change the frequency operating range to an inductive range, thereby limiting operation in the capacitive range.

[0027]

[0028] As described above, the present invention monitors the frequency operating range of an inverter circuit to determine the frequency operating range, and if the frequency operating range is determined to be a capacitive range a certain number of times or more as a result of the determination, performs the operation setting of the inverter circuit, thereby protecting the inverter circuit from being driven in the capacitive range.

[0029] The present invention can compare a voltage corresponding to a resonant current with a reference voltage and determine a frequency operating range of an inverter circuit based on a pulse signal according to the comparison result.

[0030] The present invention can limit the operation of the inverter circuit in the capacitive region by initializing the inverter circuit or switching and driving the inverter circuit at a switching frequency immediately before the capacitive region when the capacitive region is determined to be a certain number of times or more.

[0031] The present invention can prevent loss from increasing in the switching elements of an inverter circuit by satisfying ZVS operation by changing the frequency operating region to an inductive region by controlling the switching frequency for driving an inverter circuit.

[0032] The present invention generates a pulse signal by comparing the switching point of an inverter circuit with the point of resonance current, generates a trigger signal in synchronization with the falling edge of the pulse signal, and determines a frequency operating range by using the elapsed time from the start point of the switching frequency count of the inverter circuit to the point at which the trigger signal is generated, thereby enabling the frequency operating range to be determined regardless of operating conditions such as the type of container, container coupling state, and input voltage.

[0033] The present invention can protect an induction heating system by controlling a switching frequency when the frequency operating range of the induction heating system is a capacitive range, thereby changing the frequency operating range to an inductive range and thereby limiting operation in the capacitive range.

[0034] In addition, the present invention can secure stable operation of an induction heating system by initializing an inverter circuit when the frequency operating range is a capacitive range or switching and driving the inverter circuit at a switching frequency immediately before the capacitive range.

[0035] Additionally, the present invention can prevent thermal destruction of the switching element due to increased power loss of the switching element by limiting operation in the capacitive region.

[0036] Furthermore, the present invention can prevent errors caused by resonant current magnitude by detecting the resonant current point using a single comparator. This allows for accurate monitoring of the operating range of an induction heating system.

[0037] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0038]

[0039] FIG. 1 is an exploded perspective view showing a disassembled state of a cooktop in a home appliance according to one embodiment of the present invention.

[0040] Figure 2 is a drawing showing a plan view of the cooktop illustrated in Figure 1 and the configuration of the PCB pattern coil assembly.

[0041] FIG. 3 is a drawing showing an inverter circuit and a driving block of a home appliance according to one embodiment of the present invention.

[0042] Fig. 4 is a diagram showing the resonance current point detection circuit of Fig. 3.

[0043] Figures 5 to 7 are waveform diagrams showing how to determine the frequency operating range of an inverter circuit according to the timing of occurrence of a resonant current ISR (Interrupt Service Routine) trigger.

[0044] Figure 8 is a flowchart showing the interrupt service routine operation of a home appliance according to one embodiment of the present invention.

[0045] FIG. 9 is a diagram illustrating an inverter circuit and a load circuit in a home appliance according to one embodiment of the present invention.

[0046]

[0047] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0048] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0049] The present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and with various modifications. However, these embodiments are provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Therefore, the present invention is not limited to the embodiments disclosed below, but should be understood to include all modifications, equivalents, and substitutes included within the technical spirit and scope of the present invention, as well as substitutions or additions of the components of one embodiment with those of another embodiment.

[0050] The attached drawings are only intended to facilitate understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. In the drawings, the components may be expressed in an exaggerated size or thickness for convenience of understanding, etc., but the scope of protection of the present invention should not be construed as being limited thereby.

[0051] The terminology used in this specification is only used to describe specific implementations or examples and is not intended to limit the present invention. In addition, the singular expression includes the plural expression unless the context clearly indicates otherwise. In the specification, terms such as "comprises" and "consists of" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification. In other words, it should be understood that terms such as "comprises" and "consists of" in the specification do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0052] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0053] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0054] When a component is referred to as being "above" or "below" another component, it should be understood that it is not only positioned directly above that other component, but that there may also be other components intervening there.

[0055] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0056] For example, embodiments of the heating coil assembly are described herein in which the heating coil assembly is used in a cooking appliance. However, in other embodiments, the heating coil assembly may be applied to other appliances requiring induction heating.

[0057] For example, a heating coil assembly may be mounted on a washing machine and used to heat the water tank, drum, or wash tub inside the washing machine, or to heat the wash water.

[0058] As another example, the heating coil assembly may be mounted on a water purifier and used to heat a hot water pipe or tank.

[0059] As another example, the heating coil assembly may be mounted on a clothes dryer or clothes care appliance and used to heat the air for drying clothes.

[0060] As another example, a heating coil assembly may be mounted on an electric kettle or rice cooker and used to heat liquid or food inside the appliance.

[0061]

[0062] [Overall structure of an induction heating cooktop]

[0063] FIG. 1 is an exploded perspective view showing an exploded state of an induction heating cooktop (100) in a home appliance according to one embodiment of the present invention.

[0064] According to one embodiment of the present invention, a home appliance may be an oven range type in which a cooktop (100) is positioned on the upper side and an oven section is positioned on the lower side. The present invention is not limited thereto, and may be configured as a home appliance in which a cooktop (100) is provided alone.

[0065] Referring to FIG. 1, a home appliance according to an embodiment of the present invention includes an induction heating cooktop (100). The induction heating cooktop (100) may include a case (110) and a top plate (120).

[0066] According to the present embodiment, the exterior of the cooktop (100) can be formed by a case (110) and a top plate (120). The case (110) is placed below the top plate (120) and can form the front, back, side, and bottom surfaces of the cooktop (100). The top plate (120) is placed on the top of the cooktop (100) and can form the upper exterior surface of the cooktop (100). The top plate (120) can be formed of ceramic glass for holding a cooking vessel.

[0067] A receiving space may be formed inside the case (110). The receiving space formed inside the case (110) may be opened upward. As an example, the case (110) may be formed in a hexahedral shape with an open upper side. Various internal components constituting the cooktop (100) may be accommodated in the receiving space surrounded by the top plate (120) and the case (110).

[0068] In addition, the cooktop (100) may have an integrated PCB pattern coil assembly (140) disposed on the lower side of the top plate (120). The PCB pattern coil assembly (140) may have at least one heating coil for heating the cooking vessel through induction heating and at least one detection coil for detecting the cooking vessel formed integrally.

[0069] For example, the PCB pattern coil assembly (140) may be configured in multiple pieces depending on the size of the top plate (120) of the cooktop (100). For example, if the top plate (120) is divided into three left areas, a center area, and a right area, three PCB pattern coil assemblies (140) may be placed on the lower side of the corresponding areas. Each of the PCB pattern coil assemblies (140) may be formed in a different size appropriate for the sizes of the left area, the center area, and the right area. Each of the PCB pattern coil assemblies (140) corresponding to each area may be driven independently.

[0070] The PCB pattern coil assembly (140) may be formed as an integrated unit including a heating coil for induction heating, a sensing coil for container detection, a temperature sensor for temperature detection, and a terminal for connection with other components. The PCB pattern coil assembly (140) may be divided into a plurality of unit blocks. For example, one heating coil may be arranged in one unit block. For example, at least two sensing coils may be arranged in one unit block. For example, two sensing coils may be arranged between one unit block and another unit block, straddling two unit blocks.

[0071] In addition, a supporter (150) may be placed on the lower side of the PCB pattern coil assembly (140) of the cooktop (100). The supporter (150) may form a framework inside the cooktop (100) to support various internal components constituting the cooktop (100). As an example, the supporter (150) may be formed in a hexahedral shape with an open lower side. For example, the supporter (150) may be formed in a shape that is roughly an upside-down version of the case (110), and may be formed to have a size slightly smaller than the case (110).

[0072] According to the present embodiment, the accommodation space can be formed inside the supporter (150), and can be formed as a space surrounded by the bottom of the case (110) and the supporter (150). Various internal components constituting the cooktop (100) can be accommodated inside the supporter (150).

[0073] For example, the inside of the supporter (190) may accommodate a resonance PCB assembly (160) in which capacitors used for resonance or oscillation are mounted, an inverter PCB assembly (170) in which switching elements for applying current to a heating coil for induction heating are mounted, a fan (180) for cooling the heat of internal components, an EMI filter (190) for filtering and blocking various noises mixed in the power supply, and a control PCB assembly in which a controller for controlling the overall operation of the cooktop (100) and circuits for container detection are mounted.

[0074] According to the present embodiment, the supporter (150) can also provide a base function of the PCB pattern coil assembly (140). More specifically, a ferrite core can be installed on the upper side of the supporter (150), the PCB pattern coil assembly (140) can be installed on the upper side of the ferrite core, and a top plate (120) can be installed on the upper side of the PCB pattern coil assembly (140).

[0075] In addition, the cooktop (100) may be equipped with a control panel (130). The control panel (130) may be placed on an area of ​​the upper surface of the top plate (120). The control panel (130) may be equipped with a user interface (UI) including a control icon for controlling the operation of the cooktop (100) by touch and a display for indicating the operating status of the cooktop (100).

[0076]

[0077] [PCB pattern coil assembly]

[0078] FIG. 2 is a drawing showing a plan view of the cooktop (100) illustrated in FIG. 1 and the configuration of the PCB pattern coil assembly (140).

[0079] Referring to FIG. 2, the cooktop (100) may include a case (110), a supporter (150), and a PCB pattern coil assembly (140). The PCB pattern coil assembly (140) is provided to configure a heating coil (142) for induction heating of the cooktop (100) and a detection coil (143) for detecting a cooking vessel, and may be placed in a receiving space inside the cooktop (100).

[0080] A supporter (150) may be placed on the upper part of the case (110), a PCB pattern coil assembly (140) may be placed on the upper part of the supporter (150), and a top plate (120) may be placed on the upper part of the PCB pattern coil assembly (140).

[0081] The PCB pattern coil assembly (140) may include a plurality of PCB pattern coil assemblies (140) depending on the size and shape of the cooktop (100). In the present embodiment, the cooktop (100) is divided into a left region, a center region, and a right region, and is exemplified by including three PCB pattern coil assemblies (140). Each PCB pattern coil assembly (140) may include a plurality of heating coils (142) and a plurality of sensing coils (143).

[0082] Each PCB pattern coil assembly (140) can be divided into a plurality of unit blocks (141). The plurality of unit blocks (141) can be arranged in a matrix form. For example, at least one heating coil (142) can be arranged in one unit block (141). For example, at least two sensing coils (143) can be arranged in one unit block (141). In addition, at least two sensing coils (143) can be arranged between one unit block (141) and another unit block (141) to span two unit blocks.

[0083] Each heating coil (142) and sensing coil (143) formed on the PCB pattern coil assembly (140) may be arranged in a pattern shape on the substrate. For example, the heating coil (142) may be formed in a polygonal, for example, square, rectangular, or hexagonal pattern. Alternatively, the heating coil (142) may be formed in a circular pattern. For example, the sensing coil (143) may be formed in a circular, square, rectangular, or hexagonal pattern.

[0084] Additionally, the PCB pattern coil assembly (140) may be formed with at least one heating coil terminal (145), at least one sensing coil terminal (146), at least one heating coil wiring (147), at least one sensing coil wiring (148), and at least one via. The heating coil terminal (145) is electrically connected to the heating coil (142) through the heating coil wiring (147) and is electrically connected to the resonant PCB assembly (160) and the inverter PCB assembly (170). The sensing coil terminal (146) is electrically connected to the sensing coil (143) through the sensing coil wiring (148) and is electrically connected to the resonant PCB assembly (160) and the control PCB assembly.

[0085] In this way, not only a heating coil (142) but also a sensing coil (143) can be formed in the unit block (141) of the PCB pattern coil assembly (140). In the unit block (141), a plurality of sensing coils (143) are arranged along the front-back direction, and a plurality of sensing coils (143) are also arranged in the lateral direction.

[0086] The PCB pattern coil assembly (140) may include a PCB having a heating coil (142) patterned thereon (hereinafter referred to as a “heating coil PCB”) and a PCB having a sensing coil (143) patterned thereon (hereinafter referred to as a “sensing coil PCB”). The PCB pattern coil assembly (140) may be formed in a form in which the heating coil PCB and the sensing coil PCB are stacked vertically. For example, the heating coil PCB may be formed in a form in which 10 to 12 layers are stacked, and the heating coils (142) between the layers may be electrically connected through vias. For example, the sensing coil PCB may be formed in a form in which two layers are stacked, and the sensing coils (143) between the layers may be electrically connected through vias.

[0087] Additionally, at least one of the heating coil PCB and the sensing coil PCB may be provided in a form in which coils are patterned on both sides of the substrate. In the present embodiment, it is exemplified that the heating coil (142) is patterned on both sides of the heating coil PCB, and the sensing coil (143) is patterned on both sides of the sensing coil PCB.

[0088] Each sensing coil (143) may be positioned to overlap with each heating coil (142) forming region. Additionally, each sensing coil (143) may be positioned to overlap between two adjacent heating coil (142) forming regions.

[0089] In this embodiment, it is exemplified that two sensing coils (143) are respectively arranged inside each heating coil (142) forming region, and two sensing coils (143) are respectively arranged between two heating coils (142) adjacent in the front-back direction. In addition, a temperature sensor (144) may be provided in the PCB pattern coil assembly (140). For example, the temperature sensor (144) may be arranged at the center of each sensing coil (143).

[0090] As an example, the PCB pattern coil assembly (140) may be provided in a form in which a heating coil (142), a detection coil (143), and a temperature sensor (144) are integrally formed. For example, the PCB pattern coil assembly (140) may be formed in a form in which a heating coil PCB provided with a heating coil (142) and a detection coil PCB provided with a detection coil (143) and a temperature sensor (144) are laminated. The PCB pattern coil assembly (140) may be provided in a form including one or more pattern coil PCBs.

[0091] In this way, the PCB pattern coil assembly (140) has a structure in which a plurality of heating coils (142) for induction heating using a pattern printed on the PCB and a plurality of detection coils (143) for detecting a cooking vessel placed on a ceramic glass are formed as an integral part. The number of heating coils (142) and detection coils (143) can be determined according to the size of the cooktop (100).

[0092] For example, an integrated PCB pattern coil assembly (140) may include heating coil patterns arranged in a ten-layer structure, sensing coil patterns arranged in a two-layer structure, and an insulating material disposed between each heating coil pattern and each sensing coil pattern to insulate them. The insulating material may be formed by curing a prepreg composed of a thermosetting resin and glass fiber, which are generally used to form a printed circuit board. As an example, an applicable thermosetting resin is preferably an epoxy resin series, and specifically, FR-4 can be applied.

[0093] In this way, the insulating material formed through the prepreg can be placed between each heating coil pattern arranged in a layered structure to insulate them, and can be placed between each sensing coil pattern to insulate them. In addition, the insulating material can be configured to fill in areas where patterns are not formed, such as the heating coil pattern and the sensing coil pattern, to form a layered structure of individual layers.

[0094] Therefore, based on the heating coil pattern and the sensing coil pattern, the PCB pattern coil assembly (140) can have a layered structure having a total of 12 layers from the first layer forming the uppermost side to the 12th layer forming the lowermost layer based on the vertical direction.

[0095] In this way, the heating coil pattern and the sensing coil pattern according to the embodiment of the present invention are formed as an integrated PCB pattern coil assembly formed of multiple layers, thereby contributing to the simplification of processes such as masking, printing, and etching.

[0096]

[0097] [Home appliance configuration according to inverter operating range]

[0098] Fig. 3 is a diagram showing an inverter circuit and a driving block of a home appliance according to one embodiment of the present invention. Fig. 4 is a diagram showing a resonance current point detection circuit of Fig. 3. Figs. 5 to 7 are waveform diagrams showing how to determine the frequency operating range of an inverter circuit based on the point in time when a resonance current ISR (Interrupt Service Routine) trigger occurs.

[0099] Referring to FIG. 3, a home appliance according to one embodiment includes a rectifier circuit (310), an inverter circuit (320), a current detection circuit (330, 360), a load circuit (350), a resonant current point detection circuit (370), a control panel (130), a controller (500), and an inverter driving circuit (510).

[0100] The rectifier circuit (310) includes a plurality of diode elements (312) and a DC link capacitor (C1). The diode elements (312) rectify the input voltage (Vin) supplied from the power supply (302) and output a voltage having a pulsating waveform. The DC link capacitor (C1) smoothes the voltage output from the diode elements (312) and outputs a DC link voltage.

[0101] The inverter circuit (320) includes a plurality of switching elements, for example, a first switching element (DS1) and a second switching element (DS2). The first switching element (DS1) and the second switching element (DS2) are connected in series with each other between a high-potential voltage terminal and a low-potential voltage terminal. The inverter circuit (320) supplies a resonant current (Ir) to a heating coil in a load circuit (350) based on a DC link voltage supplied from a DC link capacitor (C1) according to the switching operation of the first switching element (DS1) and the second switching element (DS2).

[0102] In this way, the inverter circuit (320) can supply resonant current to the load circuit (350) according to the switching operation of the first switching element (DS1) and the second switching element (DS2). At this time, the resonant frequency of the resonant current (Ir) is determined by the inductance value of the heating coil included in the load circuit (350) and the capacitance value of the resonant capacitor.

[0103] The first switching element (DS1) and the second switching element (DS2) can be alternately turned on and off by the first switching signal (S1) and the second switching signal (S2) supplied from the inverter driving circuit (510). The alternate turning on and turning off of the first switching element (DS1) and the second switching element (DS2) can be referred to as switching driving of the first switching element (DS1) and the second switching element (DS2).

[0104] A resonant current (Ir) is generated by the switching operation of the first switching element (DS1) and the second switching element (DS2). When the resonant current (Ir) is supplied to the heating coil, a magnetic field is formed, and an eddy current flows through a container provided on top of the heating coil through electromagnetic induction, thereby heating the container.

[0105] The inverter circuit (320) further includes a first snubber capacitor (CS1) and a second snubber capacitor (CS2). The first snubber capacitor (CS1) is connected in parallel with the first switching element (DS1). The second snubber capacitor (CS2) is connected in parallel with the second switching element (SW2). The first snubber capacitor (CS1) and the second snubber capacitor (CS2) are connected in series with each other.

[0106] The first snubber capacitor (CS1) and the second snubber capacitor (CS2) serve to reduce power loss due to hard switching that occurs when the first switching element (DS1) and the second switching element (DS2) are turned off.

[0107] The control panel (130) may be equipped with a user interface including a control icon for controlling the operation of the home appliance by touch and a display for indicating the operating status of the home appliance. The user can input a target heating intensity through the control panel (130).

[0108] The load circuit (350) includes at least one heating coil and at least one resonant capacitor. Here, the at least one heating coil and the at least one resonant capacitor may be connected in series or parallel. Alternatively, the load circuit (350) includes at least one heating coil, at least one resonant capacitor, and at least one relay. Here, the at least one heating coil and the at least one resonant capacitor may be selectively connected in series or parallel through at least one relay.

[0109] The current sensing circuit includes a current converter (330) and a stabilizing circuit (360). The current converter (330) may include a primary winding (T1) and a secondary winding (T2). The primary winding (T1) may be connected between the inverter circuit (320) and the load circuit (350), and the secondary winding (T2) may be connected between a ground voltage terminal and the stabilizing circuit (360).

[0110] The number of coil turns of the primary winding (T1) and the number of coil turns of the secondary winding (T2) are inversely proportional to the magnitude of the current flowing in the primary winding (T1) and the secondary winding (T2), respectively. The number of coil turns of the secondary winding (T2) may be greater than the number of coil turns of the primary winding (T1). Accordingly, the magnitude of the current flowing in the secondary winding (T2) may be less than the magnitude of the current flowing in the primary winding (T1).

[0111] A current having a smaller magnitude than the resonant current (Ir) flowing in the primary winding (T1) can flow in the secondary winding (T2). The current flowing in the secondary winding (T2), i.e. the resonant current whose magnitude has been converted, can be supplied to the resonant current point detection circuit (370) through the stabilization circuit (360).

[0112] The stabilizing circuit (360) is connected in parallel to the secondary winding (T2) of the current converter (330). The stabilizing circuit (360) includes at least one resistor and at least one stabilizing capacitor connected in parallel to the secondary winding (T2) of the current converter (330).

[0113] In the stabilization circuit (360), at least one resistor has one side connected to a ground voltage terminal and the other side connected to an output terminal from which a resonant current (Ir) is output. A stabilization capacitor is connected in parallel with at least one resistor, and has one side connected to the ground voltage terminal and the other side connected to an output terminal. The output terminal of the stabilization circuit (360) is connected to a resonant current point detection circuit (370). This stabilization circuit (360) filters noise included in the resonant current (Ir) through at least one resistor and the stabilization capacitor.

[0114] The current detection circuit configured as above detects the resonant current (Ir) output from the inverter circuit (320) through the current converter (330) and outputs the detected resonant current (Ir) to the resonant current point detection circuit (370).

[0115] Referring to Fig. 4, the resonance current point detection circuit (370) generates a pulse signal (S_PM) based on the resonance current (Ir) output from the current detection circuit and supplies the pulse signal (S_PM) to the controller (500). The pulse signal (S_PM) is used to measure the phase difference between the resonance current (Ir) and the switching voltage of the second switching element (DS2) of the inverter circuit (320) within the controller (500).

[0116] The resonance current point detection circuit (370) can generate a pulse signal (S_PM) when the voltage corresponding to the resonance current is less than the reference voltage (Vref) and greater than zero voltage. For example, the resonance current point detection circuit (370) does not generate a pulse signal in a section where the voltage corresponding to the resonance current is greater than the reference voltage (Vref).

[0117] The resonance current point detection circuit (370) includes a first diode (D31) connected to the output terminal of the current detection circuit, a first resistor (R31) connected in series to the first diode (D31), a second diode (D32) having one end connected to a power supply voltage (5 V) terminal and the other end connected to the first resistor (R31), and a second resistor (R32) having one end connected to the first resistor (R31) and the other end connected to a ground voltage terminal.

[0118] In addition, the resonance current point detection circuit (370) includes a third resistor (R33) connected in series with the first resistor (R31), a comparator (CP1) having a first input terminal (+) connected to the third resistor (R33) and a second input terminal (-) connected to a reference voltage (Vref) terminal, and a fourth resistor (R34) connected between the output terminal of the comparator (CP1) and the first input terminal (+).

[0119] In addition, the resonance current point detection circuit (370) further includes first and second reference resistors (R36, R35) connected in series between the power supply voltage terminal and the ground voltage terminal, and a reference capacitor (31) connected between the node between the first and second reference resistors (R36, R35) and the ground voltage terminal. The node between the first and second reference resistors (R36, R35) is connected to the second input terminal (-) of the comparator (CP1) as a reference voltage terminal.

[0120] In this way, the resonance current point detection circuit (370) generates a pulse signal using a single comparator. This can reduce the accumulated error occurring in the comparator. In addition, the resonance current point detection circuit (370) can prevent errors occurring according to the size of the resonance current by detecting the resonance current point using a single comparator (CP1). This allows for accurate monitoring of the frequency operating range of the inverter circuit (320) of the induction heating appliance.

[0121] In induction heating appliances, the load is the induction vessel, due to the nature of the application. Induction vessels are broadly categorized into ferromagnetic and weakly magnetic types, each with different characteristics. The appliance measures the output power during operation by positioning the vessel at the heating coil location and controls the output power by adjusting at least one of the switching frequency and duty ratio of the inverter circuit based on the output power. Output power can be adjusted differently for ferromagnetic and weakly magnetic materials.

[0122] For example, the home appliance can drive the heating coil (142) with a lower power for a ferromagnetic container with strong magnetism than for a weakly magnetic container with weak magnetism. The power intensity according to the material of the container or the power intensity according to the change value of the equivalent resistance of the detection coil can be stored in memory. After determining the material of the container, the controller (500) can drive the heating coil (142) with a power intensity corresponding to the corresponding container.

[0123] The standard for classifying magnetic materials is determined by the formation of relative magnetic permeability. Relative magnetic permeability is the ratio of the magnetic permeability in a medium to the magnetic permeability in a vacuum, and indicates how many times the vacuum magnetic permeability is. A ferromagnetic material can be defined as a material with a relative magnetic permeability greater than 1. Ferromagnetic materials have strong magnetism, and their magnetism can change depending on temperature and an external magnetic field, and they maintain this magnetism even when the external magnetic field is removed. Iron, cobalt, and nickel are representative ferromagnetic materials. A weakly magnetic material can be defined as a material with a relative magnetic permeability equal to or slightly greater than 1. A weakly magnetic material has weak magnetism and its magnetism easily changes depending on an external magnetic field or temperature. Aluminum, platinum, and platinum are representative weakly magnetic materials.

[0124] Therefore, in order to accurately drive the heating coil with the target power suitable for the material of the container, the appliance must be able to accurately measure the output power of the load.

[0125] In one embodiment, a home appliance detects a resonant current output from an inverter circuit (320), calculates a resonant parameter including at least one of a resonant voltage and a phase based on the resonant current, and measures an output power supplied from the inverter circuit to a load circuit based on the resonant current, the resonant voltage, and the phase. Here, the phase represents a phase difference between the resonant current and the switching voltage.

[0126] The controller (500) controls the inverter drive circuit (510) to drive the load circuit (350) at the target intensity received from the control panel (130). The controller (500) controls the switching of the switching elements of the inverter drive circuit (510).

[0127] The controller (500) measures a phase margin based on a pulse signal (S_PM) output from the resonance current point detection circuit (370) and a switching frequency count value, and measures a phase difference based on the phase margin. The switching frequency count value may be defined as a value counted from the point in time when the first switching element (DS1) of the inverter circuit (320) is turned off and the second switching element (DS2) is turned on to the point in time when the first switching element (DS1) of the next cycle is turned off and the second switching element (DS2) is turned on. In this way, the switching frequency count value may be counted for one cycle of the inverter circuit (320), and the value may be initialized at intervals of one cycle.

[0128] The start time of the phase data can be defined as "switch frequency count value / 2 + dead time / 2", and the end time of the phase data can be defined as the time of the falling edge of the pulse signal (S_PM). The dead time can be defined as the time for the first switching element (DS1) and the second switching element (DS2) to alternately operate. For example, the dead time can be defined as the time it takes for the first switching element (DS1) and the second switching element (DS2) to be completely turned on or completely turned off in response to the first switching signal (S1) and the second switching signal (S2). This dead time can be set in advance and stored in the memory of the home appliance.

[0129] The controller (500) can calculate the phase difference between the resonant current and the switching voltage based on the phase data.

[0130] The controller (500) can calculate the resonance voltage as a value obtained by multiplying the input voltage (Vin) by the on-time duty of the second switching element (DS2). The controller (500) can calculate the resonance current value output to the inverter circuit (320) using the first-order regression equation for the value detected by the current detection circuit.

[0131] The controller (500) controls the resonant voltage (VINPUT x Duty), the average resonant current (I L_avg ), and the phase difference (θ) can be used to measure the output power supplied to the load circuit (350). For example, the output power can be calculated by Power = VINPUT x Duty x ILavg x cosΘ. The controller (500) can calculate the output power at least once per system control cycle, for example, every 10 ms or 8.3 ms.

[0132] The controller (500) can control the switching operation of the inverter circuit (320) by adjusting at least one of the switching frequency and duty ratio of the inverter circuit (320) according to the output power supplied to the load circuit (350).

[0133] The controller (500) can control at least one relay within the load circuit (350) to activate at least one heating coil corresponding to the position of the container depending on the position of the container.

[0134] The controller (500) measures the phase difference between the resonant current and the switching voltage of the inverter circuit (320) using only the resonant current output from the inverter circuit (320), so that the output power output from the inverter circuit (320) to the load circuit (350) can be accurately measured.

[0135] In this way, the home appliance according to one embodiment detects only the resonant current in the hardware aspect and measures the resonant voltage and phase in the software aspect to measure the output power of the load, so that the power of the load can be accurately measured regardless of changes in the heating coil or changes in the inverter PCB pattern.

[0136] According to one embodiment, a home appliance can improve the reliability of switch operation of an inverter circuit by adjusting at least one of a switching frequency and a duty ratio of an inverter circuit based on the power of a measured load.

[0137] According to one embodiment, a home appliance measures the power of a load by utilizing a resonant current resulting from current conversion of a current supplied to a load from an inverter circuit, thereby preventing the influence of noise due to resistance of a ground voltage terminal.

[0138] According to one embodiment, a home appliance can reduce the influence of noise compared to a conventional technology that measures input current using a shunt resistor, thereby improving the reliability of high-frequency driving of switching elements of an inverter circuit.

[0139] According to one embodiment, the home appliance can accurately measure the power of the load even when the container is changed to a ferromagnetic or weakly magnetic material, and thus can drive the inverter circuit at an appropriate switching frequency depending on the container material.

[0140] In induction heating appliances, the operating frequency range can be broadly divided into an inductive operating range, an operating range near the resonance point, and a capacitive operating range based on the resonant frequency. Induction heating appliances drive the inverter circuit (320) in the inductive range to reduce the power loss of the switching element. If the induction heating appliance operates in the capacitive range, the power loss of the switching element may increase, and the switching element may be thermally destroyed.

[0141] Therefore, in an induction heating appliance, the frequency operating range of the inverter circuit (320) must be monitored to protect the inverter circuit (320) from being driven in the capacitive range.

[0142] The inductive operating region can be defined as an operating range in which the resonant current is lagged by a voltage higher than the drain-source voltage of the switching element of the inverter circuit (320), thereby satisfying ZVS (Zero Voltage Switching) and generating a sinusoidal current to reduce the turn-off current of the switching element and thereby reduce the heat generation of the switching element.

[0143] The operating region near the resonance point can be defined as the operating range within which the phase difference between the drain-source voltage of the switching element and the resonant current is within the error range.

[0144] The capacitive operating region can be defined as an operating range in which the resonant current leads the drain-source voltage of the switching element of the inverter circuit (320), which increases ZVS dissatisfaction and turn-on loss of the switching element, thereby increasing heat generation of the swing element and causing damage to the switching element during long-term operation.

[0145] The capacitive operating region may occur under the following conditions. For example, in an induction heating appliance system, the possibility of capacitive operating region may increase when the minimum duty frequency is applied during the interference noise minimization logic operation, as the operation occurs near the resonance point. Alternatively, the capacitive operating region may occur when the resonance point is greater than the switching frequency limit value during the switching frequency control for constant output during the eccentric operation of the container. Alternatively, the capacitive operating region may occur when the switching frequency during the operation changes to the capacitive region when the position of the container is changed from eccentric to centered during the eccentric operation of the container.

[0146] Figure 5 shows a waveform diagram of an inverter circuit in an inductive heating appliance operating in the inductive operating range. Figure 7 shows a waveform diagram of an inverter circuit in an inductive heating appliance operating in the operating range near the resonance point. Figure 8 shows a waveform diagram of an inverter circuit in an induction heating appliance operating in the capacitive operating range.

[0147] Referring to FIGS. 5 to 7, the controller (500) determines the frequency operating range of the inverter circuit (320) based on the occurrence time of the resonant current ISR (Interrupt Service Routine) trigger. For example, the controller (500) generates the trigger signal (ISR) in synchronization with the falling edge of the pulse signal (S_PM). The controller (500) determines the frequency operating range using the elapsed time (ET) from the start time of the switching frequency count of the inverter circuit (320) to the occurrence time of the trigger signal (ISR).

[0148] As illustrated in Fig. 5, the controller (500) determines the frequency operation region as an inductive region if the elapsed time (ET) from the switching frequency count start point to the point at which the trigger signal (ISR) is generated is greater than a first reference time. The first reference time can be set to "switching frequency count value / 2 + dead time."

[0149] As illustrated in Fig. 6, the controller (500) determines the frequency operation region as a resonance point region when the elapsed time (ET) from the switching frequency count start point to the point at which the trigger signal (ISR) is generated is less than the first reference time and greater than the second reference time. The second reference time may be set to "switching frequency count value / 2 - dead time."

[0150] If the frequency operating range of the inverter circuit (320) is determined to be a resonance point range, the controller (500) determines whether to restart based on the resonance overcurrent and switch overtemperature protection logic. If resonance overcurrent or switch overtemperature is determined, the controller (500) can initialize the switching operation of the inverter circuit (320) and restart it.

[0151] As illustrated in Fig. 7, the controller (500) determines the frequency operation region as a capacitive region if the elapsed time from the switching frequency count start point to the time when the trigger signal (ISR) is generated is less than the second reference time and greater than the third reference time. The third reference time may be set to "switching frequency count value / 4."

[0152] The controller (500) sets the operation of the inverter circuit (320) when the frequency operation region is determined to be a capacitive region a certain number of times or more. Setting the operation of the inverter circuit (320) may include initializing the inverter circuit (320). In addition, setting the operation of the inverter circuit (320) may include switching and driving the inverter circuit (320) at a switching frequency immediately before the capacitive region. In addition, setting the operation of the inverter circuit may include alerting the user with a preset message. For example, the preset message may be "Please change the position of the container." Alternatively, the preset message may be "Please change to a different container."

[0153] More specifically, the controller (500) determines the frequency operating range of the inverter circuit (320) based on the pulse signal (S_PM) received from the resonant current point detection circuit (370). The resonant current point detection circuit (370) compares the voltage corresponding to the resonant current (Ir) with the reference voltage (Vref) and provides the pulse signal (S_PM) according to the comparison result to the controller (500). The controller (500) generates a trigger signal (ISR) in synchronization with the falling edge of the pulse signal (S_PM) and determines the frequency operating range by using the elapsed time (ET) from the switching frequency count start time of the inverter circuit (320) to the time when the trigger signal (ISR) is generated.

[0154] When the controller (500) determines that the capacitive region has been entered a certain number of times or more, it initializes the inverter circuit (320) and switches and drives the inverter circuit (320) at the switching frequency immediately before the capacitive region.

[0155] In addition, the controller (500) detects the capacitive region by measuring the phase difference between the switching voltage and the resonant current of the inverter circuit (320) and restricts the operation in the capacitive region. For example, if the frequency operation region of the inverter circuit (320) is determined to be the capacitive region a certain number of times or more, the controller (500) can change the frequency operation region to the inductive region by adjusting the switching frequency for driving the inverter circuit (320).

[0156] In this way, the controller (500) performs operation settings of the inverter circuit (320) including at least one of initializing the inverter circuit (320) when the frequency operating region is a capacitive region, switching and driving the inverter circuit at a switching frequency immediately before the capacitive region, and alarming the user with a preset message. In addition, the controller (500) can control the switching frequency to change the frequency operating region to an inductive region, thereby limiting the operation of the inverter circuit (320) in the capacitive region.

[0157] Figure 8 is a flowchart showing the interrupt service routine operation of a home appliance according to one embodiment of the present invention.

[0158] As shown in Fig. 8, the interrupt service routine operating in the controller (500) of the home appliance is described as follows.

[0159] The controller (500) generates a resonance current detection point (S11). For example, the controller (500) generates an interrupt service routine trigger signal (ISR) in synchronization with the falling edge of the pulse signal (S_PM) of the resonance current detection point circuit (370).

[0160] Next, the controller (500) acquires a count value of the switching frequency (S12). For example, the controller (500) acquires a switching frequency count value that is counted from the point in time when the first switching element (DS1) of the inverter circuit (320) is turned off and the second switching element (DS2) is turned on to the point in time when the first switching element (DS1) of the next cycle is turned off and the second switching element (DS2) is turned on. This switching frequency count value is counted for one cycle of the inverter circuit (320) and the value is initialized at intervals of one cycle.

[0161] Next, the controller (500) acquires the current switching frequency value (S13). For example, the controller (500) can detect a container and control the switching operation of the inverter circuit (320) at a switching frequency corresponding to the container, and can adjust the switching frequency according to the output power output from the inverter circuit (320) to the load circuit (350). In this way, the controller (500) can acquire the current switching frequency value for controlling the inverter circuit (320).

[0162] Next, the controller (500) determines whether the inverter circuit (320) operates in the inductive region (S14). For example, the controller (500) determines whether the elapsed time (ET) from the switching frequency count start time to the trigger signal (ISR) occurrence time is greater than the first reference time set as "switching frequency count value / 2 + dead time."

[0163] Next, the controller (500) determines the frequency operation area of ​​the inverter circuit (320) as an inductive area when the elapsed time (ET) is greater than “switching frequency count value / 2 + dead time” (S15).

[0164] Next, the controller (500) initializes the number of occurrences of the previously recorded capacitive operating region (S16).

[0165] In step (S14), the controller (500) determines whether the inverter circuit (320) operates in the capacitive operating region if the elapsed time (ET) is less than “switching frequency count value / 2 + dead time” (S17).

[0166] The controller (500) determines the frequency operation region as a capacitive region when the elapsed time from the switching frequency count start point to the time when the trigger signal (ISR) is generated is less than the second reference time set as “switching frequency count value / 2 - dead time” and greater than the third reference time set as “switching frequency count value / 4” (S18).

[0167] Next, the controller (500) determines whether the number of times the frequency operating region of the inverter circuit (320) is judged to be a capacitive region has occurred more than a reference number of times (S19).

[0168] Next, the controller (500) performs inverter operation settings when the frequency operation region of the inverter circuit (320) is determined to be a capacitive region more than a reference number of times (S20). For example, when the frequency operation region is determined to be a capacitive region more than a certain number of times, the controller (500) initializes the inverter circuit (320) or switches and drives the inverter circuit (320) at the switching frequency immediately before the capacitive region. In addition, the controller (500) can alarm with a message such as "Please change the position of the container" or "Please use a different container."

[0169] In this way, the controller (500) can monitor the frequency operating range of the inverter circuit (320) and adjust the switching frequency so that the inverter circuit (320) does not operate in the capacitive range.

[0170] In step (S19), the controller (500) increases the number of times the frequency operating region of the inverter circuit (320) is judged to be a capacitive region if the number of times the capacitive region occurs is less than the reference number (S21).

[0171] Returning to step (S17), the controller (500) determines the frequency operation area as a resonance point area if the elapsed time (ET) from the switching frequency count start point to the time the trigger signal (ISR) is generated is less than “switching frequency count value / 2 + dead time” and greater than “switching frequency count value / 2 - dead time” (S22).

[0172] Next, the controller (500) initializes the number of times the capacitive region occurs when the frequency operating region of the inverter circuit (320) is determined to be the resonance point region (S23). In addition, the controller (500) may determine whether to restart based on the resonance overcurrent and switch overtemperature protection logic when the frequency operating region of the inverter circuit (320) is determined to be the resonance point region. For example, the controller (500) may initialize the switching operation of the inverter circuit (320) when the resonance overcurrent or switch overtemperature is determined for the inverter circuit (320) based on the protection logic. Alternatively, the controller (500) may restart the inverter circuit (320) when the resonance overcurrent or switch overtemperature is determined for the inverter circuit (320) based on the protection logic.

[0173] In this way, the controller (500) monitors the frequency operating range of the inverter circuit (320) to determine the frequency operating range, and if the determination result is that it is a capacitive range a certain number of times or more, it performs the operation setting of the inverter circuit (320) to protect the inverter circuit from being driven in the capacitive range.

[0174] The controller (500) can limit the operation of the inverter circuit (320) in the capacitive region by initializing the inverter circuit (320) or switching and driving the inverter circuit at a switching frequency immediately before the capacitive region when the capacitive region is determined to be a certain number of times or more.

[0175] The controller (500) can prevent loss from increasing in the switching elements of the inverter circuit (320) by satisfying ZVS operation by adjusting the switching frequency for driving the inverter circuit (320) and changing the frequency operating region to an inductive region.

[0176] The controller (500) generates a pulse signal by comparing the switching point of the inverter circuit (320) with the point of resonance current, generates a trigger signal in synchronization with the falling edge of the pulse signal, and determines the frequency operating range by using the elapsed time from the switching frequency count start point of the inverter circuit (320) to the point at which the trigger signal is generated, thereby enabling the frequency operating range to be determined regardless of operating conditions such as the type of container, container coupling state, and input voltage.

[0177] The controller (500) can protect the induction heating system by controlling the switching frequency when the frequency operating range of the inverter circuit (320) is a capacitive range, thereby changing the frequency operating range to an inductive range and thereby limiting operation in the capacitive range.

[0178] The controller (500) can ensure stable operation of the induction heating system by initializing the inverter circuit (320) when the frequency operating range of the inverter circuit (320) is a capacitive range or switching and driving the inverter circuit (320) at a switching frequency immediately before the capacitive range.

[0179] The controller (500) can prevent the switching element from being thermally destroyed due to increased power loss of the switching element by limiting the operation in the capacitive region of the inverter circuit (320).

[0180]

[0181] [Inverter circuit and load circuit]

[0182] FIG. 9 is a diagram illustrating a rectifier circuit (310), a first inverter circuit (320a), a second inverter circuit (320b), and a load circuit (350) in a home appliance according to one embodiment of the present invention.

[0183] The rectifier circuit (310) converts an alternating voltage whose magnitude and polarity (positive voltage or negative voltage) change over time into a direct current voltage whose magnitude and polarity are constant, and converts an alternating current whose magnitude and direction (positive current or negative current) change over time into a direct current whose magnitude is constant.

[0184] The rectifier circuit (310) may include a bridge diode. Specifically, the rectifier circuit (310) includes four diodes (D1, D2, D3, D4). The diodes (D1, D2, D3, D4) form diode pairs (D1 and D2, D3 and D4) in which two diodes are connected in series, and the two diode pairs (D1 and D2, D3 and D4) are connected in parallel with each other. The bridge diode converts an AC voltage whose polarity changes over time into a positive voltage whose polarity is constant, and converts an AC current whose direction changes over time into a positive current whose direction is constant.

[0185] Additionally, the rectifier circuit (310) includes a DC-coupled capacitor (C1). The DC-coupled capacitor (C1) converts a positive voltage whose magnitude varies over time into a DC voltage of a constant magnitude.

[0186] The inverter circuit (320a, 320b) includes a first inverter circuit (320a) and a second inverter circuit (320b). The first inverter circuit (320a) supplies a first resonant current to the load circuit (350) through a first output terminal (OUT1) according to the switching operation of the switching elements (DS11, DS12). The second inverter circuit (320b) supplies a second resonant current to the load circuit (350) through a second output terminal (OUT2) according to the switching operation of the switching elements (DS21, DS22).

[0187] The first current detection circuit (330a) converts the first resonant current supplied from the first inverter circuit (320a) to the load circuit (350) into an intensity having a constant ratio. The converted first resonant current is provided to the resonant current point detection circuit (370). The second current detection circuit (330b) converts the second resonant current supplied from the second inverter circuit (320a) to the load circuit (350) into an intensity having a constant ratio. The converted second resonant current is provided to the resonant current point detection circuit (370).

[0188] The load circuit (350) may include at least one resonant capacitor (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) connected in series or in parallel, at least one heating coil (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8), and at least one relay (RL1, RL2, RL3, RL4, RL4, RL6).

[0189] Resonant capacitors (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) can be used to filter the DC component in the driving current. Heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) can be used to heat the cooking vessel using electromagnetic induction. Relays (RL1, RL2, RL3, RL4, RL4, RL6) can be used to selectively connect the heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) in series or parallel. Additionally, heating coils (WC1, WC2, WC3, WC4, WC5, WC6, WC7, WC8) and capacitors (CS1, CS2, CS3, CS4, CS5, CS6, CS7, CS8) can be used to determine the resonant frequency of the driving current.

[0190] The load circuit (350) may include a first resonant capacitor (CS1) that transmits a first resonant current supplied from a first inverter circuit (320a), a first heating coil (WC1) connected in series to the first resonant capacitor (CS1), a second heating coil (WC2) connected in series to the first heating coil (WC1), a second resonant capacitor (CS2) connected in series to the second heating coil (WC2), and a first relay (RL1) that switches the second resonant capacitor (CS2) and a ground voltage terminal.

[0191] In addition, the load circuit (350) may further include a third resonant capacitor (CS3) that transmits a second resonant current supplied from the second inverter circuit (320b), a third heating coil (WC3) connected in series to the third resonant capacitor (CS3), a fourth heating coil (WC4) connected in series to the third heating coil (WC3), a fourth resonant capacitor (CS4) connected in series to the fourth heating coil (WC4), and a second relay (RL2) that switches the fourth resonant capacitor (CS4) and a ground voltage terminal.

[0192] Additionally, the load circuit (350) may further include a third relay (RL3) that switches a node between the first heating coil (WC1) and the second heating coil (WC2) and a node between the third heating coil (WC3) and the fourth heating coil (WC4).

[0193] In addition, the load circuit (350) may further include a fifth resonant capacitor (CS5) that transmits a first resonant current supplied from the first inverter circuit (320a), a fifth heating coil (WC5) connected in series to the fifth resonant capacitor (CS5), a sixth heating coil (WC6) connected in series to the fifth heating coil (WC5), a sixth resonant capacitor (CS6) connected in series to the sixth heating coil (WC6), and a fourth relay (RL4) that switches the sixth resonant capacitor (CS6) and a ground voltage terminal.

[0194] In addition, the load circuit (350) may further include a seventh resonant capacitor (CS7) that transmits a second resonant current supplied from the second inverter circuit (320b), a seventh heating coil (WC7) connected in series to the seventh resonant capacitor (CS7), an eighth heating coil (WC8) connected in series to the seventh heating coil (WC7), an eighth resonant capacitor (CS8) connected in series to the eighth heating coil (WC7), and a fifth relay (RL5) that switches the eighth resonant capacitor (CS8) and a ground voltage terminal.

[0195] Additionally, the load circuit (350) may further include a sixth relay (RL6) that switches a node between the fifth heating coil (WC5) and the sixth heating coil (WC6) and a node between the seventh heating coil (WC7) and the eighth heating coil (WC8).

[0196] The current detection circuit may include a first current detection circuit (330a) that detects a first resonant current output from a first inverter circuit (320a) and a second current detection circuit (330b) that detects a second resonant current output from a second inverter circuit (320b). The first current detection circuit (330a) and the second current detection circuit (330b) may individually detect the first resonant current output from the first inverter circuit (320a) and the second resonant current output from the second inverter circuit (320b).

[0197] The resonance current point detection circuit (370) may include a first resonance current point detection circuit that compares a first voltage corresponding to a first resonance current detected by a first current detection circuit (330a) with a reference voltage and outputs a first pulse signal according to the comparison result. In addition, the resonance current point detection circuit (370) may include a second resonance current point detection circuit that compares a second voltage corresponding to a second resonance current detected by a second current detection circuit (330b) with a reference voltage and outputs a second pulse signal according to the comparison result.

[0198] The controller (500) can individually determine the frequency operating ranges of the first inverter circuit (320a) and the second inverter circuit (320b) based on the first pulse signal and the second pulse signal output from the first resonant current point detection circuit and the second resonant current point detection circuit. When the frequency operating range of the first inverter circuit (320a) or the second inverter circuit (320b) is determined to be a capacitive range a certain number of times or more, the controller (500) can individually adjust the switching frequency of the first inverter circuit (320a) or the second inverter circuit (320b).

[0199] According to one embodiment of the present invention, a home appliance includes a load circuit including at least one heating coil and at least one resonant capacitor, an inverter circuit supplying a resonant current to the load circuit according to a switching operation, a current detection circuit detecting the resonant current, a resonant current point detection circuit comparing a voltage corresponding to the resonant current detected by the current detection circuit with a reference voltage and outputting a pulse signal according to the comparison result, and a controller determining a frequency operation area of ​​the inverter circuit based on the pulse signal and performing an operation setting of the inverter circuit when the determination result determines that the frequency operation area is a capacitive area a predetermined number of times or more.

[0200] In one embodiment, the controller can generate a trigger signal in synchronization with the falling edge of the pulse signal, and determine the frequency operating region using the elapsed time from the start time of the switching frequency count of the inverter circuit to the time when the trigger signal is generated.

[0201] In one embodiment, setting up the operation of the inverter circuit may include performing an initialization operation on the inverter circuit.

[0202] In one embodiment, the operation setting of the inverter circuit may further include driving the inverter circuit at a switching frequency just prior to the capacitive region.

[0203] In one embodiment, the operation of the inverter circuit may include the performance of alerting a user with a preset message.

[0204] In one embodiment, the controller may determine the frequency operating region as an inductive region if the elapsed time is greater than the first reference time.

[0205] In one embodiment, the first reference time may be set to “switching frequency count value / 2 + dead time”.

[0206] In one embodiment, the controller may determine the frequency operating region as a resonance point region when the elapsed time is less than the first reference time and greater than the second reference time.

[0207] In one embodiment, the second reference time may be set to “switching frequency count value / 2 - dead time”.

[0208] In one embodiment, the controller may determine the frequency operating region as a capacitive region if the elapsed time is less than the second reference time and greater than the third reference time.

[0209] In one embodiment, the third reference time may be set to “switching frequency count value / 4”.

[0210] In one embodiment, the current sensing circuit may include a current converter that converts a resonant current output from the inverter circuit at a constant rate, and a stabilizing circuit that stabilizes and outputs the converted resonant current.

[0211] In one embodiment, the stabilizing circuit may include at least one resistor connected in parallel with the current transformer, one end connected to a ground voltage terminal and the other end connected to an output terminal, and a stabilizing capacitor connected in parallel with the at least one resistor, one end connected to the ground voltage terminal and the other end connected to the output terminal.

[0212] In one embodiment, the resonant current point detection circuit may include a first diode connected to an output terminal of the current detection circuit, a first resistor connected in series with the first diode, a second diode having one end connected to a power voltage terminal and the other end connected to the first resistor, a second resistor having one end connected to the first resistor and the other end connected to a ground voltage terminal, a third resistor connected in series with the first resistor, a comparator having a first input terminal connected to the third resistor and a second input terminal connected to a reference voltage terminal, and a fourth resistor connected between an output terminal of the comparator and the first input terminal.

[0213] In one embodiment, the resonant current point detection circuit may further include first and second reference resistors connected in series between a power supply voltage terminal and a ground voltage terminal, and a reference capacitor connected between a node between the first and second reference resistors and the ground voltage terminal, wherein the node between the first and second reference resistors may be connected to a second input terminal of the comparator as a reference voltage terminal.

[0214] In one embodiment, at least one heating coil may be formed as an integral multilayer PCB pattern assembly.

[0215] In one embodiment, the inverter circuit may include first and second switching elements connected in series between the high potential terminal and the low potential terminal.

[0216] In one embodiment, the controller can change the frequency operating region to an inductive region by adjusting the switching frequency for driving the first and second switching elements when the frequency operating region of the inverter circuit is determined to be a capacitive region a certain number of times or more.

[0217] In one embodiment, the inverter circuit may include a first inverter circuit that supplies a first resonant current to the load circuit, and a second inverter circuit that supplies a second resonant current to the load circuit. The current sensing circuit may include a first current sensing circuit that detects a first resonant current output from the first inverter circuit, and a second current sensing circuit that detects a second resonant current output from the second inverter circuit. The first current sensing circuit and the second current sensing circuit may individually detect the first resonant current and the second resonant current.

[0218] In one embodiment, the resonance current point detection circuit may include a first resonance current point detection circuit that compares a first voltage corresponding to a first resonance current with a reference voltage and outputs a first pulse signal according to the comparison result, and a second resonance current point detection circuit that compares a second voltage corresponding to a second resonance current with a reference voltage and outputs a second pulse signal according to the comparison result.

[0219] In one embodiment, the controller can individually determine the frequency operating regions of the first inverter circuit and the second inverter circuit based on the first pulse signal and the second pulse signal, and when the frequency operating region of the first inverter circuit or the second inverter circuit is determined to be a capacitive region a certain number of times or more, the controller can change the frequency operating region to an inductive region by adjusting the switching frequency of the first inverter circuit or the second inverter circuit.

[0220] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

Claims

1. A load circuit comprising at least one heating coil and at least one resonant capacitor; An inverter circuit that supplies resonant current to the load circuit according to a switching drive; A current sensing circuit for detecting the above resonant current; A resonance current timing detection circuit that compares the voltage corresponding to the resonance current detected by the current detection circuit with a reference voltage and outputs a pulse signal according to the comparison result; and A home appliance, comprising a controller that determines the frequency operating range of the inverter circuit based on the pulse signal, and performs operation settings of the inverter circuit when the determination result determines that the frequency operating range is a capacitive range a certain number of times or more.

2. In paragraph 1, A home appliance in which the controller generates a trigger signal in synchronization with the falling edge of the pulse signal, and determines the frequency operation range by using the elapsed time from the start time of the switching frequency count of the inverter circuit to the time when the trigger signal is generated.

3. In paragraph 2, A home appliance, wherein the operation setting of the inverter circuit includes at least one of: initializing the inverter circuit; switching the inverter circuit at a switching frequency immediately before the capacitive region; and alarming a user with a preset message.

4. In paragraph 2, The above controller determines the frequency operation area as an inductive area when the elapsed time is greater than a first reference time, and the first reference time is set to “switching frequency count value / 2 + dead time”, wherein the home appliance.

5. In paragraph 4, The above controller determines the frequency operation region as a resonance point region when the elapsed time is less than the first reference time and greater than the second reference time, and the second reference time is set to “switching frequency count value / 2 - dead time”, wherein the home appliance.

6. In paragraph 5, The above controller determines the frequency operation area as the capacitive area when the elapsed time is less than the second reference time and greater than the third reference time, and the third reference time is set to “switching frequency count value / 4”, wherein the home appliance.

7. In paragraph 1, The above current sensing circuit A current converter that converts the resonant current output from the inverter circuit at a constant rate; and A home appliance comprising a stabilizing circuit that stabilizes and outputs the converted resonant current.

8. In paragraph 7, The above stabilization circuit At least one resistor connected in parallel to the current converter, one side of which is connected to a ground voltage terminal and the other side of which is connected to an output terminal; and A home appliance comprising a stabilizing capacitor connected in parallel with at least one resistor, one side of which is connected to the ground voltage terminal and the other side of which is connected to the output terminal.

9. In paragraph 1, The above resonant current point detection circuit A first diode connected to the output terminal of the above current sensing circuit; A first resistor connected in series with the first diode; A second diode having one end connected to the power supply voltage terminal and the other end connected to the first resistor; A second resistor having one end connected to the first resistor and the other end connected to the ground voltage terminal; A third resistor connected in series with the first resistor; A comparator having a first input terminal connected to the third resistor and a second input terminal connected to a reference voltage terminal; and A home appliance comprising a fourth resistor connected between the output terminal of the comparator and the first input terminal.

10. In paragraph 9, The above resonant current point detection circuit First and second reference resistors connected in series between the power voltage terminal and the ground voltage terminal; and Further comprising a reference capacitor connected between the node between the first and second reference resistors and the ground voltage terminal, A home appliance, wherein the node between the first and second reference resistors is connected to the second input terminal of the comparator as the reference voltage terminal.

11. In paragraph 1, An appliance, wherein at least one heating coil is formed as an integral multilayer PCB pattern assembly.

12. In paragraph 1, The above inverter circuit A home appliance comprising first and second switching elements connected in series between a high-potential terminal and a low-potential terminal.

13. In paragraph 12, A home appliance in which the controller adjusts the switching frequency for driving the first and second switching elements, when the frequency operating range of the inverter circuit is determined to be a capacitive range a certain number of times or more, thereby changing the frequency operating range to an inductive range.

14. In paragraph 1, The above inverter circuit A first inverter circuit supplying a first resonant current to the load circuit; and A second inverter circuit is included that supplies a second resonant current to the load circuit, The above current sensing circuit A first current detection circuit that detects the first resonant current output from the first inverter circuit; and It includes a second current detection circuit that detects the second resonant current output from the second inverter circuit, The first current detection circuit and the second current detection circuit individually detect the first resonant current and the second resonant current, The above resonant current point detection circuit A first resonance current timing detection circuit that compares a first voltage corresponding to the first resonance current with the reference voltage and outputs a first pulse signal according to the comparison result; and A home appliance, comprising a second resonance current timing detection circuit that compares a second voltage corresponding to the second resonance current with the reference voltage and outputs a second pulse signal according to the comparison result.

15. In paragraph 14, The controller individually determines the frequency operating ranges of the first inverter circuit and the second inverter circuit based on the first pulse signal and the second pulse signal, A home appliance, wherein when the frequency operating range of the first inverter circuit or the second inverter circuit is determined to be a capacitive range a certain number of times or more, the switching frequency of the first inverter circuit or the second inverter circuit is adjusted to change the frequency operating range to an inductive range.

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