Induction heating device and control method of an induction heating device

Abstract

The present application provides an inductive heating device and a control method thereof. An inductive heating device according to an embodiment of the present application includes: a work coil disposed at a position corresponding to a heating area; an inverter circuit including a plurality of switching elements, which supplies a current to the work coil; a drive circuit, which supplies a switching signal to each of the switching elements included in the inverter circuit; a current sensor, which measures a resonance current value as a magnitude of a resonance current flowing in the work coil; and a controller, which drives the work coil by supplying a control signal for adjusting a duty ratio and a frequency of the switching signal to the drive circuit. The controller performs a container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signal, and determines whether a container exists in the heating area based on the resonance current value measured by the current sensor after the container sensing drive ends.

Description

TECHNICAL FIELD

[0001] The present application relates to an induction heating device and a control method of an induction heating device. BACKGROUND

[0002] Households or restaurants use various cooking appliances for heating food. In the past, gas stoves using gas as fuel were widely used, but in recent years, devices that heat a container such as a pot using electricity have become popular, without using gas.

[0003] Among the ways of heating a container using electricity, the induction heating method is a method of generating eddy currents in a container composed of metal components using a magnetic field generated around a coil when a high-frequency power of a predetermined size is applied to the coil, thereby heating the heating object itself.

[0004] At this time, if the current is continuously applied to the work coil in a state where the upper part of the work coil is not configured with a container, it becomes a state like idling, thereby wasting power. In addition, as the current is continuously supplied, it can cause an accident in which the induction heating device is overheated.

[0005] To solve the above-mentioned problems, as disclosed in Korean Patent Laid-Open KR10-2019-0051726, it is possible to determine whether a container is configured on the upper part of the work coil based on the resonance current generated in the work coil when the current is applied to the work coil through the inverter circuit.

[0006] However, when the induction heating device senses the container using the method disclosed in the above-mentioned Korean Patent Laid-Open, excessive noise is generated in the work coil due to the instantaneous increase in the peak to peak value of the current supplied to the work coil. Due to such driving noise, the user can feel uncomfortable every time the induction heating device is used, and depending on the situation, it can also be mistakenly assumed that a failure has occurred in the induction heating device.

[0007] Therefore, there is an urgent need to develop an induction heating device that can improve the above-mentioned problems. SUMMARY

[0008] The present application aims to provide an induction heating device and a control method of an induction heating device that can minimize driving noise generated when a container is sensed and driven.

[0009] The object of the present application is not limited to the above-mentioned object, and other objects and advantages of the present application that are not mentioned can be clearly understood by those skilled in the art through the following description, and will be further clearly understood through embodiments of the present application.

[0010] In the present invention, the controller of the induction heating device performs the container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signal.

[0011] According to the above-described feature, it is possible to minimize the drive noise generated at the time of the container sensing drive.

[0012] According to an embodiment of the present invention, an induction heating device includes: a work coil disposed at a position corresponding to a heating zone; an inverter circuit including a plurality of switching elements, which supplies a current to the work coil; a drive circuit which supplies a switching signal to each of the switching elements included in the inverter circuit; a current sensor which measures a resonance current value as a magnitude of a resonance current flowing in the work coil; and a controller which drives the work coil by supplying a control signal for adjusting a duty ratio and a frequency of the switching signal to the drive circuit, the controller performing a container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signal, and determining whether or not a container exists in the heating zone based on the resonance current value measured by the current sensor after the container sensing drive ends.

[0013] In addition, in an embodiment of the present invention, the controller starts the container sensing drive by the drive circuit supplying a switching signal having a first reference duty ratio set in advance and a first reference frequency set in advance to each of the switching elements included in the inverter circuit, and the controller performs the container sensing drive by increasing the duty ratio of the switching signal to a second reference duty ratio set in advance and decreasing the frequency of the switching signal to a second reference frequency set in advance.

[0014] In addition, in an embodiment of the present invention, the induction heating device further includes a voltage sensor which measures a supply voltage value as a voltage value supplied to the inverter circuit, and the controller starts the container sensing drive when the supply voltage value is 0. If the time for which the temperature of the indicator substrate is maintained higher than the first reference temperature is more than a reference time set in advance, the controller controls not to supply a current to the work coil through the inverter circuit.

[0015] In addition, in an embodiment of the present invention, the controller of the induction heating device increases the duty ratio of the switching signal to a second reference duty ratio set in advance, and then decreases the frequency of the switching signal to a second reference frequency set in advance after a reference time set in advance elapses.

[0016] In addition, in an embodiment of the present invention, if the supply voltage value reaches 0 V, the controller of the induction heating device ends the container sensing drive.

[0017] In addition, in an embodiment of the present application, if the resonance current value is less than a reference current value set in advance, the controller of the induction heating device determines that a container is present in the heating zone, and if the resonance current value is equal to or greater than the reference current value, the controller of the induction heating device determines that a container is not present in the heating zone.

[0018] In another embodiment of the present application, a control method of an induction heating device is provided, the induction heating device including a work coil disposed at a position corresponding to a heating zone, an inverter circuit including a plurality of switching elements, which supplies a current to the work coil, a drive circuit, which supplies a switching signal to each of the switching elements included in the inverter circuit, a current sensor, which measures a resonance current value as a magnitude of a resonance current flowing in the work coil, and a controller, which drives the work coil by supplying a control signal for adjusting a duty ratio and a frequency of the switching signal to the drive circuit, wherein the control method includes a step in which the controller performs a container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signal, a step in which the resonance current value is measured by the current sensor after the container sensing drive ends, and a step in which the controller determines whether a container is present in the heating zone based on the resonance current value.

[0019] In addition, in another embodiment of the present application, the step in which the controller performs a container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signal includes a step in which the controller starts the container sensing drive by the drive circuit supplying a switching signal having a first reference duty ratio set in advance and a first reference frequency set in advance to each of the switching elements included in the inverter circuit, and a step in which the container sensing drive is performed by increasing the duty ratio of the switching signal to a second reference duty ratio set in advance and decreasing the frequency of the switching signal to a second reference frequency set in advance.

[0020] In addition, in another embodiment of the present application, the induction heating device further includes a voltage sensor, which measures a supply voltage value as a voltage value supplied to the inverter circuit, and the step in which the control method of the induction heating device starts the container sensing drive starts when the supply voltage value is 0.

[0021] In addition, in another embodiment of the present application, the step of performing the container sensing driving by increasing the duty ratio of the switching signal to a second reference duty ratio and decreasing the frequency of the switching signal to a second reference frequency in the control method of the induction heating device includes the step of increasing the duty ratio of the switching signal to a second reference duty ratio and then decreasing the frequency of the switching signal to a second reference frequency after a lapse of a reference time set in advance.

[0022] In addition, in another embodiment of the present application, the control method of the induction heating device further includes the step of the controller ending the container sensing driving if the supply voltage value reaches 0 V.

[0023] In addition, in another embodiment of the present application, the step of the controller determining whether a container is present in the heating region based on the resonance current value in the control method of the induction heating device includes the steps of determining that a container is present in the heating region if the resonance current value is less than a reference current value set in advance, and determining that a container is not present in the heating region if the resonance current value is the reference current value or more.

[0024] According to the induction heating device and the control method of the induction heating device of the present application, each switching element included in an inverter circuit is supplied with a switching signal having a first reference duty ratio and a first reference frequency, the duty ratio of the switching signal is increased to a second reference duty ratio, and the frequency of the switching signal is decreased to a second reference frequency, thereby minimizing driving noise generated at the time of container sensing driving, so that a user does not feel uncomfortable due to the noise during use of the induction heating device, thereby having an advantage of being able to improve user satisfaction.

[0025] In addition, the induction heating device and the control method of the induction heating device of the present application have an advantage of being able to reduce the possibility that a user mistakenly recognizes that the induction heating device has a malfunction due to driving noise.

[0026] Hereinafter, specific effects of the present application are explained together with the above effects when a specific embodiment is explained. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is an exploded perspective view of an induction heating device according to an embodiment of the present application.

[0028] Figure 2 is a circuit diagram illustrating an induction heating device according to an embodiment of the present application.

[0029] Figure 3is a graph showing a resonant current value sensed by a current sensor and a supply voltage value sensed by a voltage sensor of an induction heating device according to an embodiment of the present application.

[0030] Figure 4 is a graph showing a switching signal supplied to an inverter circuit by a driving circuit at a t2 point of time of a curve of Figure 3

[0031] Figure 5 is a graph showing a switching signal supplied to an inverter circuit by a driving circuit at a t2 point of time of a curve of Figure 3

[0032] Figure 6 is a graph showing a switching signal supplied to an inverter circuit by a driving circuit at a t4 point of time of a curve of Figure 3

[0033] Figure 7 is a flowchart showing a control method of an induction heating device according to an embodiment of the present application.

[0034] BEST MODE FOR CARRYING OUT THE INVENTION

[0035] 100: induction heating device; 110: work coil; 120: inverter circuit; 130: driving circuit; 140: current sensor; 150: controller; 160: voltage sensor DETAILED DESCRIPTION

[0036] Hereinafter, the foregoing objects, features and advantages will be described in detail with reference to the accompanying drawings. In this description, detailed description of known related arts will be omitted when it is determined that it can obscure the essence of the present application. Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout.

[0037] Although the first, second, etc. terms are used to designate various structural elements, the structural elements are not limited to these terms. The terms are used only to distinguish one structural element from another. Thus, the first structural element mentioned below can also be the second structural element within the scope of the technical idea of the present application.

[0038] Hereinafter, the "upper (or lower)" of a structural element or the "on (or under)" of a structural element means not only that an arbitrary structural element is disposed so as to contact the top surface (or the bottom surface) of the structural element, but also that other structural elements can be interposed between the arbitrary structural element and the structural element disposed on (or under) the structural element. ​​​

[0039] In addition, when recited as a certain structural element is "connected", "coupled" or "linked" to another structural element, it should be understood that the structural element can be directly connected or linked to the other structural element, and other structural elements can be interposed between the structural elements, or "connected", "coupled" or "linked" to another structural element.

[0040] Throughout the specification, unless specifically stated to the contrary, each structural element can be singular or plural.

[0041] In the present specification, unless explicitly indicated to the contrary in the context, the singular expression should include the plural expression. In the present specification, the terms "comprise" or "include" should not be interpreted as necessarily including all the structural elements or steps described in the specification, but should be interpreted as not including one part of the structural elements or steps, or additionally including structural elements or steps.

[0042] Below, the induction heating device and the control method of the induction heating device of some embodiments of the present application will be described.

[0043] Figure 1 FIG. 1 is an exploded perspective view of an induction heating device according to an embodiment of the present application.

[0044] Referring to Figure 1 The induction heating device 100 according to an embodiment of the present application includes a housing 101 constituting a main body and a cover plate 102 combined with the housing 101 and sealing the inside of the housing 101.

[0045] The cover plate 102 is combined with the top surface of the housing 101 and seals the space formed inside the housing 101 from external interference. The cover plate 102 includes an upper plate portion 103 on which a container for cooking food can be placed. In an embodiment of the present application, the upper plate portion 103 can be made of a reinforced glass material such as ceramic glass, but the material of the upper plate portion 103 can vary according to the embodiment.

[0046] Heating areas 104, 105 corresponding to the work coil assemblies 106, 107, respectively, are formed in the upper plate portion 103. In order for the user to be able to clearly identify the positions of the heating areas 104, 105, lines or patterns corresponding to the heating areas 104, 105 can be printed or marked on the upper plate portion 103.

[0047] The housing 101 may have a hexahedral shape with an open upper portion. Working coil assemblies 106 and 107 for heating the container are arranged within the space formed inside the housing 101. Additionally, an interface 108 is provided inside the housing 101, which allows the user to apply power or adjust the power levels of the various heating zones 104 and 105, and displays information related to the induction heating device 100. The interface 108 may be a touch panel capable of simultaneously enabling touch-based information input and display; however, different structures of the interface 108 may be used depending on the embodiment.

[0048] Additionally, an operation area 109 is provided on the upper plate 103, positioned corresponding to the interface section 108. For user operation, text or graphics can be pre-printed on the operation area 109. Users can refer to the pre-printed text or graphics on the operation area 109 and touch specific areas of the operation area 109 to perform the desired operation. Furthermore, information output from the interface section 108 can be displayed through the operation area 109.

[0049] The user can set the power level of each heating zone 104, 105 through the interface section 108. The power level can be displayed on the operation area 118 using numbers (e.g., 1 to 9). If the power level for each heating zone 104, 105 is set, the required power value and heating frequency of the working coil corresponding to each heating zone 104, 105 are determined. Based on the determined heating frequency, the controller drives the working coils to ensure that the actual output power value of each working coil matches the required power value set by the user.

[0050] Additionally, a power supply unit 121 for supplying power to the working coil assemblies 106, 107 or the interface unit 108 is arranged in the space formed inside the housing 101.

[0051] For reference, Figure 1 In the embodiments shown, two working coil assemblies, namely the first working coil assembly 106 and the second working coil assembly 107, are exemplaryly arranged inside the housing 101. However, according to the embodiments, more than three working coil assemblies may also be arranged inside the housing 101.

[0052] The working coil assemblies 106 and 107 include: a working coil that uses a high-frequency alternating current supplied by the power supply unit 121 to form an induced magnetic field; and a heat insulation sheet for protecting the coil from heat generated by the container. For example, in Figure 1In the first working coil assembly 106, the first working coil 110 for heating the container and the first heat insulating sheet 111 are disposed in the first heating region 104. In addition, although not shown, the second working coil assembly 107 includes a second working coil and a second heat insulating sheet. According to an embodiment, the heat insulating sheet can not be disposed.

[0053] In addition, a temperature sensor is disposed in the center of each working coil. For example, in the first working coil assembly 106, the temperature sensor 112 is disposed in the center of the first working coil 110. Figure 1 In the first working coil assembly 106, the first working coil 110 for heating the container and the first heat insulating sheet 111 are disposed in the first heating region 104. In addition, although not shown, the second working coil assembly 107 includes a second working coil and a second heat insulating sheet. According to an embodiment, the heat insulating sheet can not be disposed.

[0054] In an embodiment of the present application, the temperature sensor outputs a sensing voltage corresponding to the temperature of the container, and the sensing voltage output from the temperature sensor is transmitted to the controller described later. The controller confirms the temperature of the container based on the magnitude of the sensing voltage output from the temperature sensor, and if the temperature of the container is equal to or greater than a reference value set in advance, performs an overheat protection operation of reducing the actual power value of the working coil or interrupting the driving of the working coil.

[0055] In addition, although not shown in the first working coil assembly 106, a substrate on which a plurality of circuits or elements including the controller can be mounted can be disposed in the space formed inside the housing 101. The controller can drive each working coil according to a heating start instruction of the user input through the interface portion 108, thereby performing a heating operation. If the user inputs a heating end instruction through the interface portion 108, the controller ends the heating operation by interrupting the driving of the working coil. Figure 1

[0056] Figure 2 FIG. 1 is a circuit diagram showing an inductive heating device according to an embodiment of the present application.

[0057] Referring to FIG. 1, Figure 2 The inductive heating device 100 according to an embodiment of the present application includes a working coil 110, an inverter circuit 120, a driving circuit 130, a current sensor 140, and a controller 150. Also, the inductive heating device 100 according to an embodiment of the present application can further include a voltage sensor 160. In addition, the inductive heating device 100 according to an embodiment of the present application can further include a rectifier circuit 170 and a smoothing capacitor C5.

[0058] The working coil 110 is disposed at a position corresponding to the heating region 104. The working coil 110 heats the heated body by a resonance current generated between the working coil 110 and the heated body as a current flows. The working coil 110 can receive a current from the inverter circuit 120. ​

[0059] The inverter circuit 120 includes a plurality of switching elements and supplies a current to the work coil 110.

[0060] The inverter circuit 120 can include a first switching element SW1 and a second switching element SW2. That is, as shown in FIG. 1, the inverter circuit 120 of the induction heating device 100 according to an embodiment of the present application can be configured of a half bridge circuit including two switching elements SW1 and SW2. However, in another embodiment of the present application, the inverter circuit 120 can be configured of a full bridge circuit including four switching elements. Hereinafter, an embodiment in which the inverter circuit 120 is configured of a half bridge circuit as shown in FIG. 1 will be described as a center. Figure 2 Figure 2

[0061] The inverter circuit 120 converts a current received from the external power source 200 and supplies it to the work coil 110. At this time, the current received from the external power source 200 can be supplied to the inverter circuit 120 after being rectified by the rectifier circuit 170 and smoothed by the smoothing capacitor C5.

[0062] The rectifier circuit 170 can include a plurality of diode elements, and in an embodiment of the present application, the rectifier circuit 170 can be a bridge diode circuit. The rectifier circuit 170 can rectify an alternating current input voltage received from the external power source 200 and output a voltage having a pulsating waveform.

[0063] The smoothing capacitor C5 can smooth the voltage rectified by the rectifier circuit 170 and output a direct current link voltage.

[0064] The direct current link voltage input to the inverter circuit 120 is converted into an alternating current by the turn on and turn off actions, i.e., switching actions, of the switching elements SW1 and SW2 included in the inverter circuit 120. The alternating current converted by the inverter circuit 120 is supplied to the work coil 110. As a resonance phenomenon occurs in the work coil 110, eddy currents flow in the container and heat the container.

[0065] The driving circuit 130 supplies a switching signal to each of the switching elements SW1 and SW2 included in the inverter circuit 120. At this time, the switching signal can be a pulse width modulation (PWM) signal having a duty ratio and a frequency set in advance, respectively. Hereinafter, the duty ratio will be expressed as a ratio of a time in which the switching signal is a high value within one cycle.

[0066] ​​As the driving circuit 130 supplies the switching signals, the respective switching elements SW1, SW2 included in the inverter circuit 120 are turned on or off. At this time, the first switching element SW1 and the second switching element SW2 can each be turned on or off due to the first switching signal S1 and the second switching signal S2. The respective switching elements SW1, SW2 can be turned on when the respective switching signals S1, S2 are high values, and turned off when the respective switching signals S1, S2 are low values.

[0067] The driving circuit 130 can generate the switching signals based on a control signal received from the controller 150 described later, and supply the switching signals to the inverter circuit 120.

[0068] The current sensor 140 measures a resonance current value that is a magnitude of a resonance current flowing in the work coil 110. That is, the current sensor 140 can measure the resonance current value while the work coil 110 is driven, and transmit the resonance current value to the controller 150.

[0069] The voltage sensor 160 measures a supply voltage value that is a voltage value supplied to the inverter circuit 120. In other words, the voltage sensor 160 measures the voltage value supplied from the external power source 200 as the supply voltage value. That is, the voltage sensor 160 can measure the voltage value before being rectified and smoothed by the rectifier circuit 170 and the smoothing capacitor C5. Also, the voltage sensor 160 can transmit the measured supply voltage value to the controller 150.

[0070] The controller 150 drives the work coil 110 by supplying a control signal for adjusting a duty ratio and a frequency of the switching signals S1, S2 to the driving circuit 130. That is, the controller 150 can control the driving circuit 130 by the control signal, and thus can adjust the duty ratio and the frequency of the switching signals S1, S2.

[0071] If a heating start instruction is received from the user, the controller 150 determines a frequency corresponding to a required power value of the work coil 110, that is, a heating frequency, and supplies a control signal corresponding to the determined heating frequency to the driving circuit 130. Accordingly, the switching signals S1, S2 are output from the driving circuit 130, and the work coil 110 is driven as the switching signals S1, S2 are input to the respective switching elements SW1, SW2. If the work coil 110 is driven, eddy currents are generated in the container, thereby heating the container.

[0072] Through the above-described process, the controller 150 performs a container sensing drive by setting and adjusting the duty ratio and the frequency of the switching signals S1, S2 before heating the container.

[0073] The container sensing drive is a drive for confirming whether a container is disposed in the heating region 104 corresponding to the work coil 110.

[0074] The controller 150 supplies the switching signals S1, S2 having the first reference duty ratio set in advance and the first reference frequency set in advance to the respective switching elements SW1, SW2 included in the inverter circuit 120 through the driving circuit 130, thereby being able to start the container sensing driving. Also, the controller 150 can perform the container sensing driving by increasing the duty ratio of the switching signals S1, S2 to the second reference duty ratio set in advance and decreasing the frequency of the switching signals S1, S2 to the second reference frequency set in advance.

[0075] Referring to Figures 3 to 6 the graph, the container sensing driving is explained in more detail.

[0076] Figure 3 is a graph showing the resonance current value sensed by the current sensor and the supply voltage value sensed by the voltage sensor of the induction heating device according to an embodiment of the present application.

[0077] Referring to Figure 3 , it can be confirmed that the graph showing the supply voltage value V in measured by the voltage sensor 160 and the resonance current value I R measured by the current sensor 140 is shown.

[0078] First, the controller 150 starts the container sensing driving when the supply voltage value V in is 0 V. Since the supply voltage value V in at the t1 point of time is 0 V on the graph, the container sensing driving is started at the t1 point of time. Figure 3

[0079] The controller 150 starts the container sensing driving when the supply voltage value V in is 0 V, thereby being able to minimize the driving noise that can be generated when the container sensing driving is started.

[0080] At the t1 point of time on the graph, the controller 150 can supply the switching signals S1, S2 having the first reference duty ratio set in advance and the first reference frequency set in advance to the respective switching elements SW1, SW2 included in the inverter circuit 120.

[0081] The first reference duty ratio can be set to a minimum value (for example, 20%) of the duty ratio that the switching signals S1, S2 supplied to the switching elements SW1, SW2 can have.

[0082] As described above, by setting the first reference duty ratio to the minimum value of the duty ratio, it is possible to prevent an excessive current from being supplied to the work coil 110 at the initial moment of the container sensing driving.

[0083] ​Also, the first reference frequency can be set to a high frequency (for example, 120 kHz).

[0084] At this time, it can be confirmed that the switching signals S1, S2 supplied to each switching element SW1, SW2 included in the inverter circuit 120 through the driving circuit 130 at the t1 point of time are an embodiment of the curve shown in FIG. 7. Figure 4

[0085] Figure 4 is a graph showing the curve of the switching signals supplied to the inverter circuit through the driving circuit at the t1 point of time of the curve of Figure 3

[0086] Referring to Figure 4 , it can be confirmed that the switching signals S1, S2 having the first reference duty of 20% and having the first reference frequency of 120 kHz.

[0087] At this time, the first switching element SW1 and the second switching element SW2 can act in a complementary manner. That is, the first switching signal S1 and the second switching signal S2 can have a high value H at different points of time from each other.

[0088] First, the first switching signal S1 has a high value H during the time from 0 μs to 1.67 μs and has a low value L during the remaining time in the time from 0 μs to 8.33 μs as a first cycle. Also, the second switching signal S2 has a high value H during the time from 4.17 μs to 5.83 μs and has a low value L during the remaining time in the time from 0 μs to 8.33 μs as a first cycle. Also, the same pattern can be repeated in the next cycle.

[0089] Returning again to Figure 3 , it can be confirmed that the resonance current value I R begins to gradually increase as the controller 150 supplies the switching signals S1, S2 having the first reference duty and the first reference frequency to each switching element SW1, SW2 included in the inverter circuit 120 through the driving circuit 130. Thus, it is possible to minimize the driving noise generated when the controller 150 starts the container sensing driving.

[0090] The controller 150 can start the container sensing driving by supplying the switching signals S1, S2 as Figure 4 at the t1 point of time through the driving circuit 130 and then increase the duty of the switching signals S1, S2 to the second reference duty.

[0091] ​​The second reference duty ratio can be set to a maximum value (e.g., 50%) of a duty ratio that the switching signals S1, S2 supplied to the switching elements SW1, SW2 can have. Thus, the second reference duty ratio is a value greater than the first reference duty ratio.

[0092] As described above, by increasing the duty ratios of the switching signals S1, S2 from the first reference duty ratio to the second reference duty ratio, it is possible to minimize switching loss that occurs due to switching of the switching elements SW1, SW2 with the first reference duty ratio.

[0093] At this time, the controller 150 increases the duty ratios of the switching signals S1, S2 such that the duty ratios of the switching signals S1, S2 reach the second reference duty ratio at the t2 time point. By Figure 5 An example of the switching signals S1, S2 supplied by the drive circuit 130 to each of the switching elements SW1, SW2 included in the inverter circuit 120 at the t2 time point can be confirmed.

[0094] Figure 5 is a graph showing a curve of the switching signals supplied by the drive circuit to the inverter circuit at the t2 time point of the curve of Figure 3

[0095] Referring to Figure 5 It can be confirmed that the switching signals S1, S2 have the second reference duty ratio of 50% and have the first reference frequency of 120 kHz.

[0096] At this time, the first switching element SW1 and the second switching element SW2 can operate in a complementary manner. That is, the first switching signal S1 and the second switching signal S2 can have a high value H at different time points from each other.

[0097] First, the first switching signal S1 has a high value H during a time from 0 μs to 4.17 μs and has a low value L during the remaining time in a time from 0 μs to 8.33 μs as a first period. Also, the second switching signal S2 has a high value H during a time from 4.17 μs to 8.33 μs and has a low value L during the remaining time in the time from 0 μs to 8.33 μs as the first period. Also, the same pattern can be repeated in the next period.

[0098] Returning again to Figure 3 , the controller 150 can adjust to change the switching signals S1, S2 from Figure 4 to the form of Figure 5 ​the form of the waveform, thereby being able to reduce switching loss generated due to the switching elements SW1, SW2 being switched according to the first reference duty ratio for a long time. In addition, it can be confirmed that the resonance current value I R will gradually increase. Therefore, it is possible to minimize drive noise generated when the controller 150 starts the container sensing drive.

[0099] The controller 150 increases the duty ratio of the switching signals S1, S2 to the second reference duty ratio, and then identically supplies the switching signals S1, S2 to the drive circuit 130 during a reference time set in advance. That is, on the curve, from the t2 time point to the t3 time point, the switching signals S1, S2 will not change. By the controller 150 identically maintaining the switching signals S1, S2 from the t2 time point to the t3 time point, it is possible to stabilize the frequency of the switching signals S1, S2.

[0100] The controller 150 identically maintains the switching signals S1, S2 during the reference time, and then reduces the frequency of the switching signals S1, S2 to a second reference frequency set in advance.

[0101] The frequency of the second reference frequency can be set to be lower than the frequency of the first reference frequency (for example, 60 kHz). Therefore, the second reference frequency is a value smaller than the first reference frequency.

[0102] As described above, by reducing the frequency of the switching signals S1, S2 from the first reference frequency to the second reference frequency, it is possible to reduce drive noise generated due to the inability to sufficiently transfer energy when sensing a low-efficiency container such as a weak magnet container with a high frequency such as the first reference frequency.

[0103] The controller 150 can supply the switching signals S1, S2 such as Figure 5 to the drive circuit 130 until the t3 time point, and then reduce the frequency of the switching signals S1, S2 to reach the second reference frequency at the t4 time point. By Figure 6 an embodiment of the switching signals S1, S2 supplied by the drive circuit 130 to each of the switching elements SW1, SW2 included in the inverter circuit 120 at the t4 time point can be confirmed.

[0104] Figure 6 is a graph showing the curve of the switching signals supplied by the drive circuit to the inverter circuit at the t4 time point of the curve of Figure 3

[0105] Referring to Figure 6 ​It can be confirmed that the switching signals S1, S2 having a second reference duty of 50% and a second reference frequency of 60 kHz.

[0106] At this time, the first switching element SW1 and the second switching element SW2 can operate in a complementary manner. That is, the first switching signal S1 and the second switching signal S2 can have a high value H at different time points from each other.

[0107] First, the first switching signal S1 has a high value H during a time from 0 μs to 8.33 μs among a time from 0 μs to 16.67 μs as a first period, and has a low value L during the remaining time. Also, the second switching signal S2 has a high value H during a time from 8.33 μs to 16.67 μs among a time from 0 μs to 16.67 μs as a first period, and has a low value L during the remaining time. Also, the same pattern can be repeated in the next period.

[0108] Returning again to Figure 3 , the controller 150 can adjust to change the switching signals S1, S2 from Figure 5 to Figure 6 , thereby being able to minimize the driving noise generated when performing the container sensing after operating the switching elements SW1, SW2 according to the first reference frequency.

[0109] The controller 150 reduces the frequency of the switching signals S1, S2 to the second reference frequency, and then ends the container sensing drive by interrupting the supply of the switching signals S1, S2 based on the driving circuit 130. That is, the controller 150 controls so that the switching signals S1, S2 both have a low value L.

[0110] At this time, if the supply voltage value reaches 0 V, the controller 150 can end the container sensing drive. The controller 150 can minimize the driving noise that can be generated when starting the container sensing drive by ending the container sensing drive when the supply voltage value V in is 0 V.

[0111] On the curve of Figure 4 , since the supply voltage value V in is 0 V at the t4 time point, the container sensing drive is ended at the t4 time point.

[0112] As the controller 150 controls so that the switching signals S1, S2 both have a low value L to end the container sensing drive, the work coil 110 performs autonomous resonance. Thereby, the resonance current value I R will decrease. While the work coil 110 performs autonomous resonance, the controller 150 can control the switching signals S1, S2 based on the resonance current value IR to determine whether a container exists in the heating zone 104.

[0113] Returning again to Figure 2 , the controller 150 ends the container sensing drive, and then determines whether a container exists in the heating zone based on the resonance current value measured by the current sensor 140.

[0114] At this time, if the resonance current value is less than the reference current value, the controller 150 can determine that a container exists in the heating zone 104. In contrast, if the resonance current value is greater than or equal to the reference current value, the controller 150 can determine that a container does not exist in the heating zone 104.

[0115] As described above, by supplying the switching signals S1, S2 having the first reference duty ratio and the first reference frequency to the respective switching elements SW1, SW2 included in the inverter circuit 120, the duty ratio of the switching signals S1, S2 is increased to the second reference duty ratio, and the frequency of the switching signals S1, S2 is decreased to the second reference frequency, thereby enabling the drive noise generated at the time of the container sensing drive to be minimized. In addition, by starting and ending the container sensing drive when the supply voltage value is 0 V, the drive noise generated at the time of the container sensing drive can be minimized.

[0116] Figure 7 is a flowchart illustrating a control method of an induction heating device according to an embodiment of the present application.

[0117] Referring to Figure 7 , first, the controller 150 determines whether the supply voltage value is 0 V (step S710). If the supply voltage value is not 0 V, the controller 150 waits until the supply voltage value reaches 0 V.

[0118] In addition, if the supply voltage value is 0 V, the controller 150 starts the container sensing drive. As the container sensing drive is started, the controller 150 supplies the switching signals S1, S2 having the first reference duty ratio and the first reference frequency (step S720).

[0119] Subsequently, the controller 150 increases the duty ratio of the switching signals S1, S2 to the second reference duty ratio (step S730).

[0120] Then, the controller 150 determines whether a reference time has elapsed (step S740). If the reference time has not elapsed, the controller 150 waits until the reference time elapses.

[0121] If the reference time has elapsed, the controller decreases the frequency of the switching signals S1, S2 to the second reference frequency (step S750).

[0122] After that, the controller 150 again judges whether the supply voltage value is 0 V (step S760). If the supply voltage value is not 0 V, the controller 150 waits until the supply voltage value reaches 0 V.

[0123] In addition, if the supply voltage value is 0 V, the controller 150 ends the container sensing drive. With the end of the container sensing drive, the controller 150 measures the resonance current value through the current sensor 140 (step S770).

[0124] In addition, if the resonance current value is less than the reference current value, the controller 150 judges that there is a container in the heating region 104 (step S790). In contrast, if the resonance current value is the reference current value or more, the controller 150 judges that there is no container in the heating region 104 (step S800).

[0125] According to the induction heating apparatus 100 and the control method of the induction heating apparatus 100 of the present application as described above, by supplying the switching signals S1, S2 having the first reference duty ratio and the first reference frequency to each of the switching elements SW1, SW2 included in the inverter circuit 120, the duty ratio of the switching signals S1, S2 is increased to the second reference duty ratio, and the frequency of the switching signals S1, S2 is decreased to the second reference frequency, thereby it is possible to minimize the drive noise generated at the time of the container sensing drive. In addition, by starting and ending the container sensing drive when the supply current value is 0 V, it is possible to minimize the drive noise generated at the time of the container sensing drive. As described above, by minimizing the drive noise generated at the time of the container sensing drive, it is possible to improve the satisfaction of the user since the user does not feel uncomfortable due to the noise in the process of using the induction heating apparatus 100.

[0126] As described above, although the present application has been described with reference to the example drawings, the present application is not limited to the embodiments and the drawings disclosed in the present specification, and a person of ordinary skill in the art can make various modifications within the scope of the technical idea of the present application. Also, even if the effect predictable through the structure according to the present application is not explicitly described when the embodiments of the present application are described, the effect should be recognized.

Claims

1. An inductive heating device, wherein includes: a work coil disposed at a position corresponding to a heating region; an inverter circuit including a plurality of switching elements, which supplies a current to the work coil; a drive circuit which supplies a switching signal to each of the switching elements included in the inverter circuit; a current sensor which measures a resonance current value as a magnitude of a resonance current flowing in the work coil; and a controller which drives the work coil by supplying a control signal for adjusting a duty ratio and a frequency of the switching signal to the drive circuit, the controller starts a container sensing drive by supplying a switching signal having a first reference duty ratio set in advance and a first reference frequency set in advance to each of the switching elements included in the inverter circuit through the drive circuit, the controller performs the container sensing drive by increasing the duty ratio of the switching signal to a second reference duty ratio set in advance and decreasing the frequency of the switching signal to a second reference frequency set in advance, and judges whether or not a container is present in the heating region based on the resonance current value measured by the current sensor after the container sensing drive ends.

2. The induction heating device according to claim 1, wherein the induction heating device further includes a voltage sensor which measures a supply voltage value as a voltage value supplied to the inverter circuit, the controller starts the container sensing drive when the supply voltage value is 0.

3. The induction heating device according to claim 1, wherein the controller increases the duty ratio of the switching signal to a second reference duty ratio set in advance, and then decreases the frequency of the switching signal to a second reference frequency set in advance after a reference time set in advance elapses.

4. The induction heating device according to claim 1, wherein the induction heating device further includes a voltage sensor which measures a supply voltage value as a magnitude of a voltage supplied to the inverter circuit, the controller ends the container sensing drive if the supply voltage value reaches 0 V.

5. The induction heating device according to claim 1, wherein the controller judges that a container is present in the heating region if the resonance current value is smaller than a reference current value set in advance, the controller judges that a container is not present in the heating region if the resonance current value is the reference current value or more.

6. A control method of an induction heating apparatus, the induction heating apparatus comprising: a work coil disposed at a position corresponding to a heating region; an inverter circuit including a plurality of switching elements, which supplies a current to the work coil; a drive circuit which supplies a switching signal to each of the switching elements included in the inverter circuit; a current sensor which measures a resonance current value as a magnitude of a resonance current flowing in the work coil; and a controller which drives the work coil by supplying a control signal for adjusting a duty ratio and a frequency of the switching signal to the drive circuit, wherein the control method includes: the controller starts a step of container sensing drive by supplying a switching signal having a first reference duty ratio set in advance and a first reference frequency set in advance to each switching element included in the inverter circuit through the drive circuit; a step of performing the container sensing drive by increasing the duty ratio of the switching signal to a second reference duty ratio set in advance and decreasing the frequency of the switching signal to a second reference frequency set in advance; after the container sensing drive ends, a step of measuring the resonance current value by the current sensor; and the controller judges whether or not there is a container in the heating region based on the resonance current value.

7. The control method of the induction heating device according to claim 6, wherein the induction heating device further includes a voltage sensor that measures a supply voltage value as a voltage value supplied to the inverter circuit, the step of starting the container sensing drive is started when the supply voltage value is 0.

8. The control method of the induction heating device according to claim 6, wherein the step of performing the container sensing drive by increasing the duty ratio of the switching signal to a second reference duty ratio set in advance and decreasing the frequency of the switching signal to a second reference frequency set in advance includes: a step of increasing the duty ratio of the switching signal to a second reference duty ratio set in advance, and then decreasing the frequency of the switching signal to a second reference frequency set in advance after a reference time set in advance elapses.

9. The control method of the induction heating device according to claim 6, wherein the induction heating device further includes a voltage sensor that measures a supply voltage value as a voltage value supplied to the inverter circuit, the control method of the induction heating device further includes: a step of the controller ending the container sensing drive if the supply voltage value reaches 0 V.

10. The control method of the induction heating device according to claim 6, wherein the step of the controller judging whether or not there is a container in the heating region based on the resonance current value includes: a step of judging that there is a container in the heating region if the resonance current value is smaller than a reference current value set in advance; and a step of judging that there is no container in the heating region if the resonance current value is the reference current value or more.

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