Electromagnetic oven

Abstract

The utility model relates to an induction cooker installed at the bottom of a table for induction heating, in design, a cooking container is directly placed on the table for heating, the spacing distance between the table and the cooking container is 10-60mm, and the farther the distance is within the range of more than 20mm, the higher the voltage is, mica plates are inserted into a working coil and the lower part, and the mica plates are inserted into the working coil and the lower part. High temperature generated when the voltage is high is prevented from being transmitted downwards, and meanwhile generated subtle current is insulated, so that a stable induction cooker function is achieved. The working coil comprises the following structures: a braided wire with a plurality of leads and a plastic plate for supporting the braided wire, the plurality of ferrite magnetic cores are radially arranged on the lower portion of the plastic material plate, the two connecting wires are connected to the printed circuit board side which applies high current to the two ends of the braided wire to package the power supply circuit, and the connecting wires are covered with insulating tubes so as to achieve the effects of insulation and maximum reduction of electromagnetic wave interference.

Description

Technical Field

[0001] The utility model relates to an induction cooker, in particular to an induction cooker with induction heating installed at the bottom of a table. In the design of the working coil, a flat pan or a pot and a baking tray with a predetermined height of feet are placed on the table for heating, so that the distance between the table and the cooking container is 10-60 mm. When the distance is more than 20 mm, the higher the voltage is. A mica plate is inserted under the working coil to prevent the high temperature generated when the voltage is high from being transmitted downward, and at the same time, the fine current generated is insulated. An insulating tube is covered on the wire connecting the printed circuit board and the working coil to achieve the effects of insulation and maximum reduction of electromagnetic wave interference. Background Art

[0002] The earliest known example of using the induction heating principle of an induction cooker was carried out by General Motors in North America in the 1950s. Using the induction heating principle, water was boiled by placing a newspaper between the pot and the heating device, demonstrating convenience and safety, but product production was not achieved. Thereafter, in the 1970s, Westinghouse Electric Corporation in the United States launched the CoolTop Induction Range driven at a frequency of 25 kHz and reached the stage of producing induction cookers. In addition, previous induction cookers could only heat iron cooking utensils, but after 2009, Panasonic developed an induction cooker with a different coil design and could heat non-iron cooking utensils at high frequencies. Currently, the global demand for induction cookers is increasing, and there are more and more companies supplying induction cookers. Companies researching and developing induction cookers include Bosch, Miele, Siemens in Germany, Fagor in Spain, Beko in Turkey, Smeg in Italy, Electrolux in Sweden, ARPA in France, Gorenje in Slovenia, Panasonic in Japan, GermanPool in Hong Kong, China, LG and Samsung in South Korea, etc., setting off an induction cooker craze globally. Among them, the induction cooker works on the principle of the induction heating method described above. The principle of the induction heating system is based on Ampere's law and Faraday's law. When an alternating current is applied to the coil, a magnetic field is generated according to Ampere's law. The alternating magnetic field penetrates the heater to form a time-varying magnetic field, and a voltage is induced according to Faraday's law. The induced current flows through the induced voltage and generates heat in the form of the product of the square of the induced current and the resistance.

[0003] In addition, in a traditional induction cooker, heat is transferred to the lower part of the working coil, resulting in problems such as circuit failures and reduced durability due to overheating; current is supplied to the coil through wires, and due to the electromagnetic wave interference of these wires, there are problems such as reduced reliability of product quality and inconvenience to users. The electromagnetic interference (obstruction or interference), EMI is defined as "electromagnetic waves, whether radiated or conducted, that cause malfunctions in other electronic devices" and can have an impact that weakens the function of electronic circuits and causes discomfort in operation. Due to this problem, the unnecessary electromagnetic wave emissions of electronic devices should be controlled below a certain level. EMI noise is divided into radiation noise and conductive noise. Radiation noise is EMI that directly propagates into the space of the victim, such as interference caused by electromagnetic waves for communication such as radio or portable radios, corona discharge of transmission lines, and noise during motorcycle ignition. Conductive noise is different from the signals that originally need to be transmitted in signal lines, control lines, power supply lines, etc. connected between electronic devices or circuits, and is EMI that is conducted to the victim through these wires.

[0004] An induction cooker is a typical household electrical appliance product. Harmonic distortion is generated by the working coil of non-linear components, and EMI is generated due to transient phenomena caused by high-speed switching of high voltages. As described above, electromagnetic interference has radiation and conductivity. Since induction heating equipment uses a frequency of 20KHz to 30KHz and the switching frequency is not that high, the impact of conductive EMI transmitted through the power supply line is greater than the electromagnetic interference (EMI) caused by radiation.

[0005] In addition, Patent Document 1 discloses a technology in Korean Registered Patent No. 10-1015763 (registered on February 10, 2011), that is, in the process of using an induction cooker, in order to prevent the heat generated by the object to be heated from being conducted into the induction cooker and causing problems with the coil, a heat insulation material is applied to the inner wall of the upper plate of the induction cooker. While improving the cooling efficiency of the coil, it can also obtain the heat preservation effect of the object to be heated, but it cannot prevent the phenomenon that the high temperature generated when the voltage is high is excessively conducted to the lower part of the coil. Since the microcurrent generated by the coil flows downward and interferes with the circuit board, there is also a situation where a stable operation of the circuit cannot be formed.

[0006] Patent Document 2 discloses a power control driving method in Korean Registered Patent No. 10-2453613 (registered on October 06, 2022). This power control driving method uses an MCU to rapidly switch PowerMOSFETs including IGBTs and SiC power components, causing a high-frequency current to flow through the working coil, inducing eddy currents in the cooking container, and minimizing electromagnetic wave interference inevitably generated in the induction heating inverter device that generates heat. Patent Document 3 is a Korean Published Patent No. 10-2023-0016960 (published on February 03, 2023), which discloses an electric stove having a temperature sensing unit capable of stably sensing the temperature of the cover plate. Patent Document 4 is a Korean Registered Patent No. 10-1531213 (registered on June 18, 2015), which discloses an electromagnetic coil that effectively heats a cooking container smaller than the diameter of the electromagnetic coil by forming a coil portion with a relatively small diameter. However, at this time, there is a noise problem due to the magnetic field generated outside the cooking container. To solve this problem, it effectively heats a cooking container with a small diameter and maximizes the transmittance and thermal efficiency through an IGBT structure that can stably maintain a high output. Utility Model Content

[0007] The present utility model has been studied to solve the above problems. The purpose of the present utility model is to provide an induction cooker with an improved structure. The details of the improved structure are as follows:

[0008] First, in the design of the working coil, the voltage is higher when the distance between the working coil and the cooking container is farther within the range of 20 - 60 mm. Even when the distance between the working coil and the cooking container reaches more than 20 mm, stable heating can be performed. Second, when using a frying pan or a pot, and a barbecue plate (grill pan) with a predetermined height of feet on the table, that is, in a state where the distance between the working coil and the cooking container reaches more than 20 mm, effective insulation and maximum reduction of electromagnetic wave interference (EMI, Electro-Magnetic Interference) effects can be achieved even when a high voltage is applied, thereby enabling stable heating. Third, this induction cooker can effectively prevent the temperature heated by the induction heating of the working coil from being transferred below the coil.

[0009] To achieve the above object, the present utility model provides an induction cooker, which includes a power supply circuit, an AC-DC conversion circuit, a main control unit, an IGBT drive circuit, a working coil, and a communication interface / cooling fan drive circuit. The power supply circuit rectifies the alternating current of the AC power supply through a bridge rectifier after passing through an EMI filter, and then converts it into a stable current that suppresses unnecessary signals and EMI contained in the commercial power supply through a coil filter and an inverter circuit, and supplies it to the IGBT drive circuit to start the working coil. The power supply circuit converts the alternating current into direct current through an AC-DC converter, and then supplies DC18V and 5V power to the main control unit and the communication interface / cooling fan drive circuit through a DC-DC high-voltage conversion circuit and a DC-DC low-voltage conversion circuit. The main control unit outputs a pulse width modulation (PWM) signal, amplifies the signal through an IGBT driver, and starts the IGBT drive circuit, so that an induced magnetic field is generated when current passes through the working coil, causing the cooking container body to absorb the magnetic field and turn into eddy currents at the same time, thereby generating cooking heat;

[0010] The working coil includes a braided wire (Litz wire) having multiple wires and a plastic material plate for supporting the braided wire. The working coil is composed of a plurality of ferrite cores radially arranged under the plastic material plate and two connecting wires for connecting to the printed circuit board side of the power supply circuit that applies high current to both ends of the braided wire. The connecting wires are covered with insulating tubes to achieve the effects of insulation and maximum reduction of electromagnetic wave interference.

[0011] The present utility model also provides an induction cooker, which includes the following structures: a housing, a working coil and a printed circuit board, a power input part, and a power / temperature regulator. A cooling fan is provided at the lower part of the housing, and the upper part of the housing is covered with an upper plate. The working coil and the printed circuit board are arranged on the bottom surface of the upper plate inside the housing;

[0012] The power input part and the power / temperature regulator are arranged on one side of the housing. The working coil includes a braided wire (Litz wire) having multiple wires and a plastic material plate for supporting the braided wire. The working coil is composed of a plurality of ferrite cores radially arranged under the plastic material plate and two connecting wires for connecting to the printed circuit board side of the power supply circuit that applies high current to both ends of the braided wire. The connecting wires are covered with insulating tubes to achieve the effects of insulation and maximum reduction of electromagnetic wave interference.

[0013] In a preferred embodiment, the insulating tube is composed of a double-layer structure in which ceramic fibers, glass fibers, or carbon fibers are braided in a cylindrical shape on the outer side of the inner silicon tube, so as to improve insulation and have excellent heat resistance, thereby preventing deterioration caused by the high temperature generated inside the induction cooker.

[0014] In a further preferred embodiment, a mica plate with a predetermined thickness is inserted between the braided wire and the plate, and the mica plate can prevent the temperature heated by the induction heating of the working coil from being transmitted to below the working coil and improve the insulation function of the working coil.

[0015] According to an embodiment of the present invention, in the design of the working coil, the farther the distance between the working coil and the cooking container is within the range of 20 - 60 mm, the higher the voltage. When a barbecue grill (griddle) with attached legs of a non-flat pan or pot is placed on a table for use, that is, when the distance between the working coil and the cooking container reaches more than 20 mm, stable heating can also be carried out. Install an induction cooker at the bottom of the dining table, place only a thin silicon pad on the table (dining table), and place a cooking container or a griddle with attached legs directly on the table to heat the cooking container or the griddle. Safety and convenience can be achieved in use. Install an EMI filter in the power circuit, cover a double-layer silicon pad on the connecting wire connected between the printed circuit board and the working coil, and connect double-layer insulated electron tubes, etc. Even when a high voltage is applied to the working coil, electromagnetic interference (Electro-Magnetic Interference) can be minimized. Insert a mica plate between the working coil and the plate, thereby effectively preventing the temperature heated by the induction of the working coil from being transmitted to below the working coil, and having the beneficial effect of effectively preventing phenomena such as deterioration of the printed circuit board.

[0016] Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the internal structure of an induction cooker based on the present invention.

[0018] Figure 2 It is Figure 1 a schematic diagram of the external shape of the shown induction cooker.

[0019] Figure 3 It is Figure 1 a front schematic diagram of the shown working coil.

[0020] Figure 4 It is Figure 1 a reverse schematic diagram of the shown working coil.

[0021] Figure 5 It is a power supply circuit and an AC-DC conversion circuit diagram of an induction cooker based on the present invention. ​

[0022] Figure 6 It is the main control unit and IGBT drive circuit diagram of the induction cooker based on the present utility model.

[0023] Figure 7 It is the communication interface / cooling fan drive circuit diagram of the induction cooker based on the present utility model.

[0024] Figure 8 It is a schematic diagram of installing the induction cooker of the present utility model at the bottom of a table.

[0025] Figure 9 It is a schematic diagram of installing the induction cooker of the present utility model on a table.

[0026] In the figure: 1: induction cooker; 10: cooling fan; 20: upper plate; 30: housing; 40: working coil; 41: Litz wire; 42: plastic material plate; 43: ferrite core; 44: connecting wire; 45: insulating tube; 46: mica plate; 50: printed circuit board (PCB); 60: power input part; 70: power / temperature regulator; 80: fixing bracket; 100: power supply circuit; 110: AC power supply (commercial power supply); 120: EMI filter; 130: bridge rectifier; 140: coil filter; 150: inverter circuit; 200: AC-DC conversion circuit; 210: AC-DC converter; 220: DC-DC high voltage conversion circuit; 230: DC-DC low voltage conversion circuit; 300: main control unit; 310: IGBT driver; 400: IGBT drive circuit; 400, 320, 430, 440: IGBT switching element; 411, 421, 431, 441: free wheel diode; 412, 432: buffer capacitor; 500: communication interface / cooling fan drive circuit; 510: coil temperature detection circuit; 520: buzzer drive circuit; T: table; R: cooking container (frying pan, baking tray, etc.); S: temperature sensor. Specific embodiments

[0027] In the description of the present utility model, it should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0028] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0029] In the description of the present utility model, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0030] To make the purpose, technical solution and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the scope of the present utility model. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concept of the present utility model.

[0031] Next, the preferred embodiments of the present utility model will be described in detail according to the drawings without limiting the present utility model.

[0032] Figures 1 to 4 There are physical pictures of the induction cooker based on the present utility model shown. Figures 5 to 7 There are various circuit diagrams of the induction cooker constituted based on the present utility model shown. Figure 8 and Figure 9 respectively represent the installation and use states of the present utility model.

[0033] Embodiment 1

[0034] As shown in the figure, the induction cooker 1 based on this embodiment includes the following structures: a housing 30, a working coil 40, a printed circuit board 50, a power input unit 60, a power / temperature regulator 70, and a plurality of fixing brackets 80. The lower part of the housing 30 is provided with a cooling fan 10, and the upper part is covered with an upper plate 20. The working coil 40 and the printed circuit board 50 are arranged on the bottom surface of the upper plate 20 inside the housing 30. The power input unit and the power 60 / temperature regulator 70 are arranged on one side of the housing 30.

[0035] The fixing bracket 80 is used to mount the induction cooker 1 on the bottom of the table (T).

[0036] The induction cooker 1 of this embodiment is installed in the center of the table (T), that is, the fixing bracket 80 installed with screws suspends and fixes the edge. The center of the fixing bracket 80 is located at the center of the working coil 40, and a space with a distance of at least 15 cm from the floor must be ensured under the table (T) to fully cool the heat generated during use.

[0037] In addition, as Figure 9 shown, the power / temperature regulator 70 connected to the main body of the induction cooker 1 by wires is installed after drilling holes on one side of the upper surface of the table (T) using a drill bit and a jigsaw. The user only needs to press the power button and the temperature adjustment button (︿, ﹀ arrows) of the power / temperature regulator 70 to operate by touch, and the power on / off state and the firepower adjustment stage can be visually confirmed on the LCD window. Press the power button for about 2 seconds, and the power will be in the on (ON) state. Press the power button again, and the P5 gear will be lit and start. Regarding the firepower adjustment, use the temperature adjustment button (︿, ﹀ arrows) to appropriately adjust the firepower and then use it. After pressing the power button in the startup state, it will be converted to the ON mark to end the heating, and the LCD window will automatically close after 30 seconds.

[0038] On the one hand, the firepower adjustment is set between multiple gears of P1 to P7. In the P7 gear with the highest temperature, it will automatically return to the P1 gear after 15 minutes of startup and automatically turn off after 60 minutes. In the P6 gear, it will automatically return to the P1 gear after 20 minutes of startup. In the P5 gear, it will return to the P1 gear after 25 minutes of startup. In the P4 gear, it will return to the P1 gear after 30 minutes of startup. In the P3 gear, it will return to the P1 gear after 40 minutes of startup. In the P2 gear, it will return to the P1 gear after 50 minutes of startup. After returning to the P1 gear, it will automatically turn off after 50 minutes. A timer is set for the firepower adjustment to automatically turn off, which can prevent fires caused by overheating and exert a safety function effect.

[0039] On the other hand, the LCD window lights up various error codes according to the situation, showing E0 when there is no cooking container; showing E1 / E2 when the AC voltage is lower or higher than the predetermined voltage respectively; showing E3 or E4 (when the IGBT circuit is abnormal) when the circuit is abnormal; showing E5 when the cooking surface is too hot or when heating an empty container; showing E6 when the IGBT is overheated, which is convenient for taking corresponding measures.

[0040] Embodiment 2

[0041] In addition, the induction cooker 1 based on this embodiment includes the following circuits: a power supply circuit 100, an AC-DC conversion circuit 200, a main control unit 300, an IGBT drive circuit 400, the working coil 40, and a communication interface / cooling fan drive circuit 500.

[0042] As Figure 5 shown, in the power supply circuit 100, the AC power supply 110; the alternating current of the commercial power supply passes through the EMI filter 120, is rectified by the bridge rectifier 130, and then passes through the coil filter 140 and the inverter circuit 150 to convert it into a stable current that suppresses unnecessary signals and EMI of the commercial power supply, forming a voltage waveform with the frequency required for input to the working coil 40.

[0043] The output voltage frequency generated in the power supply circuit 100 is determined according to the resonance frequency and the output level. The resonance frequency and the output level can be obtained through the inductance coefficient of the working coil 40 and the capacitor (inverter circuit) of the power supply 100. When the frequency is higher than the resonance frequency, the impedance increases, the magnitude of the current decreases, and the output power decreases. Therefore, the output power intensity can be divided into stages. When the output power intensity decreases, if the frequency is adjusted to be lower than the resonance frequency, the fluctuation amplitude of the output is large and it is difficult to accurately control. Therefore, in the design, the output power intensity is set to the maximum level near the resonance frequency, and the output power intensity is reduced by further increasing the frequency.

[0044] In addition, as Figure 5 shown, regarding the commercial power supply (AC) provided by the power supply circuit 100, it is converted into DC through the AC-DC converter 210, and through the DC-DC high-voltage conversion circuit 220 and the DC-DC low-voltage conversion circuit 230, DC 18V and 5V power supplies can be provided to the printed circuit board 50 on which the main control unit 300 and the communication interface / cooling fan drive circuit 500 are installed.

[0045] That is, the 18V power supply is activated by the IGBT drive circuit 400 and the communication interface / cooling fan drive circuit 500, and the 5V power supply is activated by the main control unit 300 and the coil temperature detection circuit 510.

[0046] In addition, asFigure 6 As shown, regarding the main control unit 300 (MCU) outputting a control signal to control the turning on and off of the fan, outputting a pulse width modulation (PWM) signal to control the increase and decrease of the heating output, amplifying the signal through the IGBT driver 310, starting the IGBT drive circuit 400, a current passes through the working coil 40 to generate an induced magnetic field, causing the cooking vessel body (not shown in the figure) to absorb the magnetic field and become eddy currents, thereby generating heat for cooking. The magnitude of the working current, the cooking surface temperature, and the commercial power supply voltage are detected.

[0047] In the drawing, the symbol 320 is the working current detection circuit. After the alternating current passes through the current transformer, it is converted into a DC signal through the diode rectifier circuit and transmitted to the control chip, that is, the main control unit 300.

[0048] The IGBT drive circuit 400 has the following structure: four freewheeling diodes (411, 421, 441) connected between the collectors and emitters of the first to fourth IGBT switching elements (410, 420, 430, 440) and the IGBT switching elements (410, 420, 430, 440), and snubber capacitors (412, 432) connected between the collectors and emitters of the first and third IGBT switching elements (410, 430).

[0049] Between the neutral points of the series circuits of the first IGBT switching element 410 and the third IGBT switching element 410, a series circuit of the working coil 40 for heating the cooking vessel and the first resonant capacitor 450 is connected. In the first resonant capacitor 450, a series circuit of the second resonant capacitor 460 and the switch relay switch 470 is connected in parallel. Therefore, the two series circuits form a resonant circuit.

[0050] Figure 7 The communication interface / cooling fan drive circuit 500 is shown in the figure. The communication interface / cooling fan drive circuit 500 is connected to the circuit of the main board, the 5V power input, the 3.3V power input, the AD input signal, the control board communication interface, outputs a PWM signal, is connected to the signal output port of the main control unit 300, drives the cooling fan 10 to rotate, discharges the heat inside the housing 30, reduces the internal environmental temperature of the housing 30, and maintains the normal operation of the induction cooker, that is, the working coil 40. The buzzer drive circuit 520 is connected to the signal output port of the main control unit 300, and when the temperature control button or function operation is completed, it warns the user and communicates with the user through sound.

[0051] The symbol 530 in the drawing is the display panel interface circuit. The control chip communicates with the display panel through this display panel interface circuit to transmit display signals and display relevant status parameters. The symbol 540 is the display panel signal detection circuit. When the control chip detects the connection of the display panel, it transmits data; when the display panel is not detected, it does not transmit data. In addition, the symbol 550 is the communication circuit between the chip board and the lamp board. Since the operating voltage of the control chip on the chip board is different from that of the control chip on the lamp board, the corresponding voltage signal can be converted through this communication circuit to achieve normal communication.

[0052] In addition, the symbol 560 is the switch detection circuit. It outputs a high level through the resistor (R36). After connecting the switch, it transmits the signal with the changed level to the control chip. The symbol 570 is the cooling fan drive circuit. When the signal is 1, the fan starts to work; when the signal is 0, the fan stops working.

[0053] The basic circuits of the induction cooker 1, namely the power supply circuit 100, the AC-DC conversion circuit 200, the main control unit 300, the IGBT drive circuit 400, and the communication interface / cooling fan drive circuit 500, are well-known components in the technical field to which the present invention belongs. Therefore, detailed descriptions thereof are omitted. Below, the characteristic configurations and effects of the induction cooker 1 based on the present invention will be described.

[0054] First, the structural characteristics of the working coil 40 of the induction cooker based on the present invention are as follows:

[0055] The working coil 40 of the induction cooker based on the present invention is composed of the following structures: a flat-type braided wire 41 (Litz wire), a plastic material plate 42, multiple ferrite cores 43, and two connecting wires 44. The flat-type braided wire 41 (Litz wire) is formed by aggregating multiple fine wires. The plastic material plate 42 is formed by mixing PBT (polybutylene terephthalate) and glass fiber for supporting the braided wire 41. The multiple ferrite cores 43 are radially arranged below the plate 42. The two connecting wires 44 are connected to the printed circuit board side for applying high current to both ends of the braided wire 41.

[0056] In addition, in the induction cooker 1 based on the present invention, an insulating tube 45 covers the braided wire 41 of the working coil 40 and the connecting wire 44 connecting to the printed circuit board, so as to effectively insulate the current emitted from the connecting wire 44 and minimize electromagnetic wave interference.

[0057] The insulating tube 45 is composed of a double structure in which a ceramic fiber or a glass fiber or a carbon fiber is braided into a cylindrical shape outside the inner silicon tube, so as to maximize the insulation effect and have excellent heat resistance, and can prevent the deterioration phenomenon of high-temperature heat generated inside the induction cooker.

[0058] In addition, in the induction cooker 1 based on the present utility model, a mica plate 46 with a predetermined thickness is inserted between the braided wire 41 and the plastic material plate 42, so as to effectively prevent the temperature heated by the induction of the working coil 40 from being transmitted to the lower part of the working coil, and improve the insulation function of the working coil 40.

[0059] In the present utility model, the thickness of the mica plate 46 is preferably 0.8 mm or more. In this embodiment, a mica plate 46 with a thickness of 1 mm is applied.

[0060] In this embodiment, the working coil 40 generates an alternating magnetic field by obtaining the output voltage applied from the power supply circuit 100, and the generated alternating magnetic field is amplified by the ferrite core 43. The ferrite core 43 is sometimes used as the magnet core of a transformer and an inductor due to its high magnetic permeability and low conductivity. Different from the iron core of the solenoid coil used in a transformer and an inductor, due to the structural characteristics of the induction cooker using the flat braided wire 41, it is arranged in a radial structure on the bottom surface of the working coil 40.

[0061] Regarding the working coil 40, that is, the magnetic field generated by the braided wire 41 and the ferrite core 43 can affect the components mounted on the printed circuit board 50. Therefore, a mica plate 46 serving as a shielding plate and an insulating plate is additionally mounted on the plastic material plate 42.

[0062] Since the working coil 40 has structural variables caused by the length and number of turns of the coil, as well as electrical variables composed of the voltage and frequency applied to the flat coil, and the current, current density, resistance and inductance coefficient flowing through the coil. Therefore, using the numerical values of the variables and their respective relationships, the working coil 40 and various cooking vessels (R) at a position 10 - 60 mm away are designed for suitable heating. In this embodiment, the braided wire 41 is composed of two thin wires 102 with a diameter of 0.19 mm, and the inner diameter is The outer diameter is The specification and shape are concentric circles with 62 turns of two-layer laminations, and the inductance coefficient (L) is 600 ± 10 uH.

[0063] In addition, 22 ferrite cores 43 are arranged radially outward according to the specification of thickness * width * length of 5 * 15 * 50 mm, or 6 ferrite cores 43 are arranged radially inward according to the specification of thickness * width * length of 5 * 15 × 40 mm.

[0064] Based on the induction cooker 1 of this embodiment, the magnetic field intensity is improved by increasing the number of induction systems of the working coil 40, so that long-distance heating can be carried out, that is, induction heating can be performed on the cooking container at a position 20 to 60 mm apart. That is, as the distance between the cooking container (R), such as an iron pot, a frying pan, or a baking tray with legs, and the working coil 40 continuously increases from 10 mm to 60 mm, the magnetic field intensity of the cooking container (R) induced by the working coil drops sharply, and the working coil cannot detect the cooking container. In this embodiment, the number of induction systems of the cooking container (R) is increased to improve the magnetic field intensity of the cooking container (R), thereby achieving long-distance heating. Therefore, a frying pan or a pot, as well as various baking trays with predetermined height legs, can be placed on the table for use.

[0065] On the other hand, in this embodiment, the temperature sensor (S) is installed at the center of the working coil 40 to keep in contact with the bottom of the upper plate 20. A further preferred method is to perforate the center of the upper plate 20 to expose the temperature sensor (S) to the outside, so as to directly detect the lower temperature of the table, and prevent fires that may occur when the cooking container is heated by an empty container. And existing induction cookers are provided with temperature sensors under the glass upper plate to measure the indirect heat of the upper and lower plates of the glass upper plate, so as to solve the problem of inaccurate temperature measurement of the cooking container. When the induction cooker is attached to the bottom of the table, the upper plate 20 of the induction cooker will not be exposed to the outside, thus not causing problems such as water flowing into the induction cooker, and approaching the actual measurement of the cooking container temperature to the greatest extent. When overheated, that is, when the temperature detected by the temperature sensor (S) is 80 to 90 °C, the operation of the induction cooker can be blocked to prevent fires caused by overheating.

[0066] In addition, when the temperature sensor is installed in a protruding (exposed) state on the upper plate, if there are unexpected things such as iron or screws on the table, these situations will be reflected in the induction cooker, and the situation of the table itself catching fire can be prevented.

[0067] As described above, the induction cooker 1 based on this embodiment has the following advantages: the farther the distance between the working coil 40 and the cooking container (R) is within the range of 20 to 60 mm, the higher the voltage. Therefore, the induction cooker 1 is installed at the bottom of the table, with only a thin silicon pad placed at the bottom of the table, and the cooking container (R) is placed on it to heat the cooking container (R). Or, in the case of no silicon pad, a baking tray with legs is placed on the table, which can achieve safe and convenient use effects. An EMI filter 120 is used in the power supply circuit 100, and a double-insulated wire is connected between the printed circuit board and the working coil 40. Even when a high voltage is applied to the working coil 40, it has high-efficiency insulation and can minimize the electromagnetic wave interference effect. And by inserting a mica plate 46 between the working coil 40 and the plastic material plate 42, the temperature heated by the induction heating of the working coil 40 is prevented from being transmitted below the working coil 40, thereby preventing the deterioration of the printed circuit board.

[0068] It should be noted that although the above embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, any changes and modifications made to the embodiments described in this article, or equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present invention, and directly or indirectly applying the above technical solutions to other related technical fields are all included in the patent protection scope of the present invention.

Claims

1. An induction cooker, characterized in that: It includes a power supply circuit (100), an AC-DC conversion circuit (200), a main control unit (300), an IGBT drive circuit (400), a working coil, and a communication interface / cooling fan drive circuit (500). The power supply circuit (100) rectifies the AC current of the AC power supply (110) after passing through the EMI filter (120), and then converts it into a commercial stable current through the coil filter (140) and the inverter circuit, and supplies it to the IGBT drive circuit (400) to start the working coil (40). The power supply circuit (100) converts the AC current into DC through the AC-DC converter (210), and then supplies DC 18V and 5V power to the main control unit (300) and the communication interface / cooling fan drive circuit (500) through the DC-DC high-voltage conversion circuit (220) and the DC-DC low-voltage conversion circuit (230). The main control unit (300) outputs a pulse width modulation signal, amplifies the signal through the IGBT driver (310), and starts the IGBT drive circuit (400) so that when current passes through the working coil (40), an induced magnetic field is generated, enabling the cooking container body to absorb the magnetic field and at the same time become eddy currents to generate cooking heat. The working coil (40) includes a braided wire (41) having multiple wires, and a plastic material plate (42) for supporting the braided wire (41). The plastic material plate (42) is composed of a plurality of ferrite cores (43) radially arranged at the lower part and two connecting wires (44) for connecting to the printed circuit board side of the power supply circuit including the braided wire (41) at both ends. The connecting wires (44) are covered with an insulating tube (45).

2. The induction cooker according to claim 1, wherein: The insulating tube (45) is composed of a double-layer structure woven in a cylindrical shape using ceramic fiber or glass fiber or carbon fiber outside the inner silicon tube.

3. The induction cooker according to claim 1, characterized in that: A mica plate (46) with a predetermined thickness is inserted between the braided wire (41) and the plastic material plate (42). The mica plate (46) prevents the temperature heated by the induction heating of the working coil (40) from being transferred below the working coil (40).

4. The induction cooker according to claim 1, characterized in that: A temperature sensor (S) is installed at the center of the working coil (40), and the temperature sensor (S) is exposed on the upper plate (20) of the induction cooker (1).

5. The induction cooker according to claim 1, characterized in that: The braided wire (41) is composed of two thin wires with a diameter of 0.19 mm, and the inner diameter is The outer diameter is The specification and shape are concentric 2-layer laminations wound 62 times, and the inductance coefficient is 600 ± 10 uH; 22 ferrite cores (43) are radially arranged outward according to the specification of thickness * width * length of 5 * 15 * 50 mm, or 6 ferrite cores (43) are radially arranged inward according to the specification of thickness * width * length of 5 * 15 × 40 mm.

6. The induction cooker according to any one of claims 1 to 5, characterized in that: It includes the following structures: a housing (30), a working coil (40), a printed circuit board (50), a power input unit (60), and a power / temperature regulator (70). A cooling fan (10) is provided at the lower part of the housing (30), and an upper plate (20) covers the upper part of the housing (30). The working coil (40) and the printed circuit board (50) are disposed on the bottom surface of the upper plate (20) inside the housing (30), and the power input unit (60) and the power / temperature regulator (70) are disposed on one side of the housing (30). The working coil (40) includes a braided wire (41) having multiple wires, and a plastic material plate (42) for supporting the braided wire (41). The lower part of the plate (42) is composed of a plurality of ferrite cores (43) radially arranged and two connection wires (44) for connecting to the printed circuit board (50) side of the power supply circuit including applying a high current to both ends of the braided wire (41). The connection wires (44) are covered with an insulating tube (45).

7. The induction cooker according to claim 6, wherein: A mica plate (46) having a predetermined thickness is inserted between the braided wire (41) and the plate (42), and the mica plate (46) prevents the temperature heated by the induction heating of the working coil (40) from being transferred below the working coil (40).

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