KR102594320B1 - Induction heating cooker - Google Patents

Abstract

The present invention relates to an induction heating cooker that suppresses heat generation from a switching element included in an induction cooker by varying the capacitance within each induction cooker, or reduces or prevents interference noise by reducing the difference in resonance frequency between a plurality of induction cookers. .
The present inventor's induction heating cooker includes at least one driving unit that operates each of at least one induction cooking unit with variable capacitance, and an input unit that obtains a set heating power and a set duty or heating power level for each of the at least one induction cooking unit from the user. and each of the at least one driving unit is controlled to operate the at least one induction cooking unit with the set heating power and setting duty, or with the setting heating power and setting duty corresponding to the heating power level, among the at least one induction cooking unit. When a single induction cooker performs a heating operation, a control unit is provided that checks the resonance frequency of the single induction cooker and performs a capacitance adjustment process of varying the capacitance of the single induction cooker based on the confirmed resonance frequency. do.

Description

Induction heating cooker {INDUCTION HEATING COOKER}

The present invention relates to an induction heating cooker, and in particular, to suppress heat generation of a switching element included in an induction cooker by varying the capacitance within each induction cooker, or to reduce interference noise by reducing the difference in resonance frequency between a plurality of induction cookers. It relates to an induction heating cooker that prevents.

The induction heating method is a method of providing cooking heat to a cooking vessel. A method of heating the cooking vessel by causing an induced current to be generated in the cooking vessel made of a magnetic material due to the magnetic field generated as current is supplied to the working coil formed inside the main body. This means that induction ranges, rice cookers, pans, cook tops, and slow cookers are representative cooking appliances that use the induction heating method.

Among conventional induction heating cookers, an induction range includes a main body with an accommodating space, first and second induction cookers mounted on the accommodating space to form an induced current at the bottom of the cooking vessel and operating independently of each other, and an upper side of the accommodating space. and a top portion that covers the first and second induction burners and indicates a cooking area on the upper side corresponding to the first and second induction burners, and each of the first and second induction burners has at least one working coil. It is configured to include, and the induction heating cooker in this specification is explained focusing on the induction range.

The resonance frequencies of the first and second induction burners are different depending on the thermal power set for each of the first and second induction burners and the material, size and shape of the cooking vessel placed in the cooking area above the first and second induction burners. do. If a cooking vessel is placed on each of the first and second induction burners and the first and second induction burners operate simultaneously, the difference between the resonance frequencies of the first and second induction burners is within the audible frequency band (about 2 kHz to 20 kHz). If included, interference noise occurs. This interfering noise causes considerable discomfort to the user and may cause the user to suspect that the induction cooker is malfunctioning.

In order to prevent such interference noise, the prior art separates the first and second induction cookers by a considerable distance (about 10 cm) or more (hereinafter referred to as “first prior art”), or separates the first and second induction cookers from each other by a considerable distance (about 10 cm) or more. The first and second driving units for each control were provided with a half-bridge type inverter circuit in which two IGBT elements were applied per induction cooker (hereinafter referred to as the “second prior art”).

In the case of the first prior art, if the main body is standardized to a certain area (volume) (the area (volume) occupied by the main body in the kitchen sink is almost constant), in order to sufficiently space the first and second induction cookers, the first or The diameter of the second induction burner (for example, a working coil) must be reduced, and the first or second induction burner with such a small diameter has a problem in that it is difficult to generate strong fire power.

In addition, in the case of the second prior art, the half-bridge type inverter circuit has a disadvantage in that the circuit structure becomes complicated and its production price also increases.

The present invention suppresses heat generation of a switching element (for example, an IGBT element) included in an induction cooker by varying the capacitance within each induction cooker, and reduces interference noise by reducing the difference in resonance frequency between a plurality of induction cookers. The purpose is to provide an induction heating cooker that prevents

In addition, the present invention adjusts the heating power and duty of each induction burner to prevent the plurality of induction burners from operating simultaneously without reducing the set heating amount (set integrated power) of the plurality of induction burners. The purpose is to provide a heating cooker.

In addition, the present invention uses the principle that the heating power and resonance frequency of the induction cooker are inversely proportional to adjust the heating power so that the difference in resonance frequency of the plurality of induction cookers is not included in the audible frequency band (for example, 2 kHz or less or 20 kHz or more). The purpose of the present invention is to provide an induction heating cooker that maintains a set heating amount (set integrated power) by adjusting the duty when the heating power is adjusted while performing frequency change control.

The present inventor's induction heating cooker includes at least one driving unit that operates each of at least one induction cooking unit with variable capacitance, and an input unit that obtains a set heating power and a set duty or heating power level for each of the at least one induction cooking unit from the user. and each of the at least one driving unit is controlled to operate the at least one induction cooking unit with the set heating power and setting duty, or with the setting heating power and setting duty corresponding to the heating power level, among the at least one induction cooking unit. When a single induction cooker performs a heating operation, a control unit is provided that checks the resonance frequency of the single induction cooker and performs a capacitance adjustment process of varying the capacitance of the single induction cooker based on the confirmed resonance frequency. do.

In addition, the control unit operates the single induction cooker at minimum heating power and full duty, and preferably checks the resonance frequency of the single induction cooker from the driving unit.

In addition, the control unit preferably compares the confirmed resonance frequency with a reference resonance frequency to determine the necessity of varying the capacitance of the single induction cooking surface.

In addition, if the confirmed resonance frequency is greater than the reference resonance frequency, the control unit determines that the capacitance needs to be changed, and preferably changes the capacitance of the single induction cooker.

In addition, the induction heating cooker of the present invention includes a plurality of driving units that respectively operate a plurality of induction cooking utensils with variable capacitance, an input unit that obtains a set heating power and a setting duty or heating power level for each of the plurality of induction cooking utensils from the user, and , each of the plurality of driving units is controlled to operate the plurality of induction cookers with the set heating power and set duty, or with the set heating power and set duty corresponding to the heating power level, wherein the plurality of induction cookers perform a heating operation. In this case, the plurality of induction burners are alternately operated at the set heating power and set duty to check the resonance frequencies of the plurality of induction burners from the plurality of driving units, respectively, and the difference (absolute value) between the resonance frequencies is used as a standard. and a control unit that performs a capacitance adjustment process to vary the capacitance of one of the plurality of induction cookers.

In addition, the control unit preferably compares the difference (absolute value) between the resonance frequencies with a reference frequency for capacitance adjustment to determine the necessity of varying the capacitance.

In addition, when the difference (absolute value) between the resonance frequencies is greater than the reference frequency, the control unit determines that the capacitance needs to be changed, and changes the capacitance of one induction cooker among the plurality of induction cookers. desirable.

In addition, the control unit preferably changes the capacitance of the induction cooker having a larger resonance frequency among the resonance frequencies.

In addition, the control unit preferably stores operation history information indicating whether it has determined the need to vary capacitance for the single induction cooker or the plurality of induction cookers.

Additionally, the operation history information preferably includes one of a set state or a reset state.

In addition, when the operation history information is in a reset state, the control unit determines the necessity of changing the capacitance, and the control unit preferably sets the operation history information to a set state.

In addition, the control unit preferably changes the capacitance of the at least one induction cooker or the plurality of induction cookers to a minimum capacitance and sets the operation history information to a reset state.

The invention is a switching element included in the induction cooker (e.g. , IGBT element), and has the effect of reducing or reducing interference noise by reducing the difference in resonance frequency between a plurality of induction burners.

In addition, the present invention adjusts the heating power and duty of each induction cooker to perform duty stagger control to prevent the plurality of induction cookers from operating simultaneously without reducing the set heating amount (set integrated power) of the plurality of induction cookers, It is effective in preventing interference noise.

In addition, the present invention uses the principle that the heating power of an induction stove is inversely proportional to the resonance frequency, and adjusts the heating power so that the difference between the resonance frequencies of a plurality of induction stoves is not included in the audible frequency band to prevent interference noise and adjust the heating power. This has the effect of maintaining the set heating amount by adjusting the duty.

In addition, the present invention selectively performs duty stagger control or frequency change adjustment control, and compensates for the loss of heating amount due to the rising time of the thermal power when the operation of the induction cooker starts, allowing the induction cooker to output the set heating amount. It works.

In addition, in the present invention, when performing the output operation of another induction cooker during the output operation of one induction cooker, the duty-on operation is performed simultaneously after turning off the duty of all of the plurality of induction cookers, so that the output operation of the plurality of induction cookers is performed simultaneously. This has the effect of preventing interference noise.

1 is a configuration diagram of the induction heating cooker according to the present invention.
FIG. 2 is a flowchart of control operations performed by the induction heating cooker of FIG. 1.
FIG. 3 is a flowchart of the frequency control process included in the control operation of FIG. 2.
FIG. 4 is a flowchart of the capacitance adjustment process included in the control operation of FIG. 2.
FIG. 5 is a flowchart of the capacitance adjustment process performed in the frequency control process of FIG. 3.
FIG. 6 is a graph explaining the heating amount compensation process performed by the induction heating cooker of FIG. 1.
FIG. 7 is a graph illustrating the operation control process of induction cookers performed in the frequency control process performed by the induction heating cooker of FIG. 1.

In the following, the present invention is explained in detail through examples and drawings.

Figure 1 is a configuration diagram of the induction heating cooker of the present invention. The induction heating cooker includes a commercial power supply unit (1) that receives commercial AC power, first to third rectifier units (3-1 to 3-3) that receive commercial AC power and supply direct current voltage, and allow the user to select a cooking utensil and An input unit 5 that obtains commands such as start and end of operation, selection or change of heat power (or heat power level), selection of a cooking menu, start and end of cooking, and start and end of operation of the selected cooking area, and selected or changed heat power. , a display unit (7) that displays a cooking menu, cooking start and end, etc., and at least one working coil (WC1) and (WC2), respectively, and first and second rectifying units (3-1) and (3-2). ) is supplied with a direct current voltage to perform induction heating resonance, the internal capacitance is variable, and the first and second induction cookers (8) and (9) operate independently of each other, and the control signal from the control unit (20). The first and second driving units 18 and 19, which operate the first and second induction burners 8 and 9, respectively, and control the above-mentioned components, so that the first and second driving units operate according to user commands. It consists of a control unit 20 that controls (18) and (19). However, the power supply unit 1, the input unit 5, the display unit 7, and the first and second driving units 18 and 19 correspond to configurations widely known to those skilled in the art to which the present invention pertains, and thus will not be described in detail. Explanation is omitted. Although the present invention is explained through an induction heating cooker having first and second induction burners (8) and (9), it can also be applied to an induction heating cooker having three or more induction burners.

The first rectifier (3-1) is composed of a diode bridge (BD1) to which commercial AC power is applied from the power supply unit (1), a choke coil (L1), and a capacitor (C1), and the second rectifier (3-2) ) is composed of a diode bridge (BD2) to which commercial AC power is applied from the power supply unit (1), a choke coil (L2), and a capacitor (C2). In addition, the third rectifier 3-3 receives commercial AC power and supplies the DC voltage required for the first and second driving units 18 and 19, the input unit 5, the display unit 7 and the control unit 20. Create and authorize. In this specification, the first to third rectifying units (3-1 to 3-3) are collectively referred to as the rectifying unit (3).

The first induction cooker 8 includes a first variable capacitance unit that receives a direct current voltage from the first rectifier unit 3-1 and has a variable capacitance, a working coil (WC1) connected in parallel to the first variable capacitance unit, and a first variable capacitance unit (WC1) connected in parallel to the first variable capacitance unit. 1 It consists of a variable capacitance unit and a first switch (SW1) connected between the working coil (WC1) and the first rectifier unit (3-1). The first variable capacitance unit is connected in parallel to the first path including a first capacitor C1-1, and performs conduction/interruption (ON/OFF) of the current by the control unit 20. It consists of a second path consisting of a first relay unit (RLY1) and a second capacitor (C2-1) connected in series to the first relay unit (RLY1). The first variable capacitance unit has the capacitance (minimum capacitance) of only the first capacitor (C1-1) when the first relay unit (RLY1) is in the blocking state (OFF), and the first relay unit (RLY1) is in the conducting state (ON) ), it has a capacitance (maximum capacitance) that is the sum of the capacitance of the first capacitor (C1-1) and the capacitance of the second capacitor (C1-2). Accordingly, the resonant frequency of the first induction burner 8 is affected by the minimum capacitance and the inductance of the working coil (WC1) or the maximum capacitance and the inductance of the working coil (WC1), and is affected by the change in the capacitance of the first variable capacitance unit. The resonance frequency of the first induction burner 8 is also varied.

In addition, the second induction cooker 9 also receives a direct current voltage from the second rectifier unit 3-2 in the same way as the first induction cooker 8 and includes a second variable capacitance unit whose capacitance is variable, and a second variable capacitance unit. It consists of a working coil (WC2) connected in parallel, a second variable capacitance unit, and a second switch (SW2) connected between the working coil (WC2) and the second rectifier unit (3-2). The second variable capacitance unit is connected in parallel to the first path and a first path including a second capacitor C2-1, and performs conduction/interruption (ON/OFF) of the current by the control unit 20. It consists of a second path consisting of a second relay unit (RLY2) and a second capacitor (C2-2) connected in series to the second relay unit (RLY2). The second variable capacitance unit has the capacitance (minimum capacitance) of only the first capacitor (C2-1) when the second relay unit (RLY2) is in the blocking state (OFF), and the second relay unit (RLY2) is in the conducting state (ON) ), it has a capacitance (maximum capacitance) that is the sum of the capacitance of the first capacitor (C2-1) and the capacitance of the second capacitor (C2-2). Accordingly, the resonant frequency of the second induction burner 9 is affected by the minimum capacitance and the inductance of the working coil (WC2) or the maximum capacitance and the inductance of the working coil (WC2), so that the change in capacitance of the second variable capacitance unit The resonance frequency of the second induction burner 9 is also varied.

The minimum capacitance and maximum capacitance of the first induction cooker 8 may be the same as or different from the minimum capacitance and maximum capacitance of the second induction cooker 9, but in this embodiment, the same case is exemplified.

If the capacitance of the first and second induction burners (8) and (9) is excessively small, the resonance frequency of the first and second induction burners (8) and (9) becomes high and the first and second induction burners (8) and (9) become high at resonance. Since the heat generation of the switches (SW1) and (SW2) intensifies and the resonance voltage also increases, which may cause damage to the first and second switches (SW1) and (SW2), these first and second switches (SW1) , the minimum capacitance is determined to prevent heat generation and damage to (SW2). In addition, if the capacitance in the first and second induction burners (8) and (9) is excessively large, the resonance frequency becomes low, resulting in loss due to switching loss of the first and second switches (SW1) and (SW2) during resonance. As the voltage increases, the heat generation of the first and second switches (SW1) and (SW2) may worsen, so the maximum capacitance is set to prevent the heat generation of the first and second switches (SW1) and (SW2) from worsening. is decided.

In addition, the induction heating cooker of the present invention includes a power supply unit (1), a rectifier unit (3), an input unit (5), a display unit (7), first and second induction cookers (8) and (9), and first and second driving units ( 18), 19 and a main body (not shown) with a receiving space for accommodating the control unit 20, and an upper side covering the upper side of the receiving space and corresponding to the first and second induction burners 8 and 9. It is provided with a top plate (not shown) that displays the cooking area, and the input unit 5 and display unit 7 are installed on the front of the top plate.

In addition, when the control unit 20 performs an operation (output) function for one of the first and second induction cookers 8 and 9 selected, the control unit 20 operates in the same way as the induction heating cooker in the prior art. A first or second driving unit 18 to operate the selected induction cooker with a set fire power (or fire power level) set by the user and a duty (or duty ratio) corresponding to the set fire power or with a set fire power and duty set by the user. , controls (19). Table 1 below is a data table showing the correspondence between the thermal power stage, thermal power, and duty, and the corresponding relationship between the accumulated power, which is the heating amount according to the thermal power stage (thermal power and duty).

firepower level One 2 3 4 5 6 7 8 9 10 fire power
(W) 1100 1100 1100 1100 1100 1100 1100 1300 1500 1800 duty
(Sec) 1.1/6 1.6/6 2.2/6 2.7/6 3.8/6 4.9/6 6/6 6/6 6/6 6/6 Integration
power
(Wh) About 200 About 300 About 400 About 500 About 700 About 900 1100 1300 1500 1800

In the case where only a single induction burner operates, the control unit 20 operates the first or second driving unit 18, (19) to perform a heating operation according to the thermal power and duty corresponding to each thermal power stage according to the data table in Table 1. ) is controlled. Here, the duty is expressed as on time (sec)/duty cycle. For example, 1.1/6 means that the induction cooker operates (ON) for 1.1 seconds out of 6 seconds, and for 4.9 seconds (6 - 1.1), the induction cooker stops operating ( OFF), and the integrated power (Wh) refers to the heating amount when heated for 1 hour at the selected thermal power level and is calculated as “thermal power (W) x duty.” Additionally, the control unit 20 performs a capacitance adjustment process to prevent the heat generation of the first or second switches SW1 and SW2 from worsening. In this capacitance adjustment process, the control unit 20 maintains the first and second relay units (RLY1) and (RLY2) in a blocked state and operates the first or second induction cooking utensils (8) and (9) selected by the user. ), and if the confirmed resonance frequency exceeds the reference resonance frequency (Rf) for preventing heat generation, the first or second relay units (RLY1) and (RLY2) are operated in a conductive state to 2 This is to reduce the resonance frequency of the induction burners (8) and (9).

An example of the resonance frequency according to the capacitance variation of the cooking vessel and the first or second induction cooker (8) and (9) is shown in Table 2 below.

division Firepower stage 7 levels (1100W) 8 levels (1300W) 9 levels (1500W) 10 levels (1800W) Application of container A Ieast
capacitance 35kHz 34 kHz 32 kHz 31kHz maximum
capacitance 30kHz 29kHx 28 kHz 27kHz B container application Ieast
capacitance 43kHz 41kHz 40kHz 38kHz maximum
capacitance 37kHz 36kHz 34kHz 33kHz

Here, containers A and B are containers with different electrical characteristics, and in all containers, it was confirmed that the resonance frequency of the induction cooker with the maximum capacitance was reduced by approximately 4 to 6 kHz compared to the resonance frequency of the induction cooker with the minimum capacitance. do. This reduction in resonance frequency prevents the heat generation of the first and second switches SW1 and SW2 from worsening.

Additionally, the capacitance adjustment process can be applied not only when a single inverter burner is operating, but also when a plurality of inverter burners are operating. For example, the resonance frequencies of the first inverter fire bowl (8) to which container A is applied and the second inverter fire bowl (9) to which container B is applied (the first and second inverter fire bowls (8) and (9) are all at the minimum (In the case of capacitance), the difference between the resonance frequencies is 8kHz at 35kHz and 43kHz at 7 levels of thermal power, respectively. However, when the second relay (RLY 2) of the second inverter firebox 9 is converted to a conducting state at the same thermal power, the resonance frequency of the second inverter fireball 9 is reduced to 37 kHz, and the first and second inverter fireballs ( The difference between the resonance frequencies of 8) and (9) is significantly reduced to 2 kHz, and the interference noise is also significantly reduced by reducing the difference between these resonance frequencies.

In addition, the control unit 20 checks the resonance frequency of the first and/or second induction cooking utensils (8) and (9) that are in operation while performing the capacitance adjustment process and controls the first or second relay units (RLY1) and (RLY2). ) (see FIG. 4) or whether the first or second relay units (RLY1) and (RLY2) are operated in the conducting and blocking states (see FIG. 5). Stores operation history information representing .

The control unit 20 stores the operation history information in a reset state as the initial state when manufacturing the induction heating cooker or at the end of the control method, and the first and/or second operation history information is operated only when the operation history information is in the reset state. By checking the resonance frequencies of the induction burners (8) and (9), the necessity of conducting operation of the first or second relay units (RLY1) and (RLY2) is determined, and the operation history information is set to a set state and stored. In addition, when the condition of the number of induction cooking utensils in operation remains the same, the control unit 20 controls the first and/or second induction cooking utensils 8 and 9 based on operation history information (set state). Prevents unnecessary repetitive checking of the resonance frequency. For example, when the number of induction cookers in operation increases, a single induction cooker in operation is turned off and then turned on again, or the cooking vessel is removed and returned, the first and/or second induction cooker (8), ( You can also check the resonance frequency in 9) again.

In addition, the control unit 20 controls only one of the first or second relay units (RLY1) and (RLY2) to be in a conductive state, or controls both the first and second relay units (RLY1) and (RLY2) to be in a disconnected state. do.

Next, when it is necessary to operate a plurality of inverter cooking utensils, the control unit 20 performs an interference noise prevention method including a capacitance adjustment process. This interference noise prevention method allows the control unit 20 to operate the first and second inverter burners (8) without overlapping operation times with respective heating powers set for the first and second inverter burners (8) and (9) within the duty cycle. ) and (9) are additionally included in the duty-staggered control process of operating each alternately. This duty stagger control process operates only the first inverter burner (8) during the duty corresponding to the heating power of the first inverter burner (8), the second inverter burner (9) stops operating, and the first inverter burner (8) is operated. After the duty corresponding to the heating power of , the process of operating only the second inverter cooking area 9 during the duty corresponding to the heating power of the second inverter cooking area 9 is sequentially repeated.

In addition, the interference noise prevention method is such that when the thermal power of the first and second induction cooking pots (8) and (9) is lowered, the resonance frequency of the first and second induction cooking pots (8) and (9) is increased, and the first and second induction cooking pots (8) and (9) are lowered. Using the principle that when the heating power of the second induction burner (8) and (9) increases, the resonance frequency of each of the first and second induction burners (8) and (9) decreases, the first and second induction burners ( It additionally includes a frequency change control process to adjust the heating power of each of 8) and (9) so that the difference between the resonance frequencies of the first and second induction burners (8) and (9) is not included in the audible frequency band. .

Examples of resonance frequencies according to the size of the cooking vessel and the heating power level (or heating power) of the first and second induction burners 8 and 9 are shown in Table 3 below.

division Firepower level 7 levels (1100W) 8 levels (1300W) 9 levels (1500W) 10 levels (1800W) Resonant frequency when C container is applied to the first induction burner (8) 38.9kHz 37.2 kHz 35.5 kHz 34kHz Resonant frequency when D container is applied to the second induction burner (9) 33.7kHz 32.1kHz 30.5kHz 29.5kHz

Additionally, in Table 4 below, it is confirmed that the difference between resonance frequencies is reduced by the frequency change control process.

fireball Before frequency change control After frequency change control fire power
(W) duty
(Sec) Accumulated power
(Wh) resonance
frequency
(KHz) fire power
(W) duty
(Sec) Accumulated power
(Wh) resonance
frequency
(KHz) 1st induction burner (8) 1100W 6/6 1100 38.9 1800W 3.66/6 1099 34 2nd induction burner (9) 1100W 6/6 1100 33.7 1100W 6/6 1100 33.7 Differences between resonant frequencies 5.2 0.3

In Table 4, in the case before the frequency change control, the difference between the resonance frequency of the first induction cooker 8 and the resonant frequency of the second induction cooker 9 is 5.2 kHz, and the difference is included in the audible frequency band, so interference noise is not generated. It happens quite a bit.

Through the frequency change control process, the control unit 20 increases the thermal power of the first induction burner 8 from 1100W to 1800W, and increases the duty from 6/6 to 3.66 so that the accumulated power before changing the heating power and the accumulated power after changing the heating power are the same. Adjust to /6. Due to this frequency change control, the difference between the resonance frequency of the first induction cooker 8 and the resonant frequency of the second induction cooker 9 is 0.3 kHz, and the difference is not included in the audible frequency band, so that interference noise is not generated. It almost never happens.

When operating a single induction cooker, only the capacitance adjustment process is used, but when operating multiple induction cookers, the capacitance adjustment process, frequency change control process, and duty shift control process included in the interference noise prevention method are first and second. It may be performed independently or sequentially depending on the set duties for the induction burners 8 and 9, differences between resonance frequencies, etc., and is described in detail below.

FIG. 2 is a flowchart of control operations performed by the induction heating cooker of FIG. 1. In the starting stage, the control unit 20 starts a heating operation according to the cooking range selection, heating power level, and cooking start input or operation start input input by the user from the input unit 3. In the following description, the set heating power (P1) is the set heating power (heating power corresponding to the set heating power level) of the first induction cooking pot (8), and the setting heating power (P2) is the setting heating power of the second induction cooking pot (9), The set duty (D1) is the set duty (duty corresponding to the set heating power level) of the first induction burner (8), the set duty (D2) is the set duty of the second induction burner (9), and the duty (Dp) is This is the duty cycle. In addition, the thermal power (P1-1) is the increased thermal power of the first induction burner (8) (thermal power greater than the thermal power corresponding to the set thermal power level), and the thermal power (P2-1) is the increased thermal power of the second induction burner (9). , the duty (D1-1) is the reduced duty of the first induction burner (8) (a duty smaller than the duty corresponding to the set heating power level), and the duty (D2-1) is the reduced duty of the second induction burner (9). am.

In step S1, the control unit 20 determines whether a plurality of induction cooking utensils are in operation according to a user input from the input unit 3. If the plurality of induction burners, i.e., the first and second induction burners 8 and 9, are in operation, the process proceeds to step S3. Otherwise, the process proceeds to step S25.

In step S3, the control unit 20 determines whether duty stagger control can be performed based on the set duties D1 and D2. If the sum of the set duty (D1) and (D2) is less than or equal to the duty cycle (Dp), the control unit 20 operates the first induction cooker 8 during the set duty (D1) within the duty cycle (Dp). Since the second induction cooker 9 can be operated during the set duty (D2) after the set duty (D1), that is, duty stagger control can be performed, proceed to step (S5), otherwise, the duty cycle ( Since there is an overlap time between the set duties (D1) and (D2) within Dp), the process proceeds to step (S7).

In step S5, the control unit 20 controls the first and second induction burners 8 and 9 with the set thermal powers (P1) and (P2) and set duties (D1) and (D2). The duty shift control for operating the second induction burners (8) and (9), respectively, begins to be performed. In this duty shift control, the set duty (D2) is turned on and off immediately after the set duty (D1) is turned on and off within the duty cycle (Dp). You can wait until the next duty cycle, and the set duty (D1) is turned on and off from the start of one duty cycle (Dp), and the set duty (D2) is turned on and off at the end of the duty cycle (Dp). ) is set to be OFF. Determine the ON point of duty (D2) and set in the middle period when set duty (D2) is turned on and set duty (D1) and (D2) do not overlap. Both duty (D1) and (D2) may be turned OFF. In performing duty stagger control, the induction hob that is duty-operated first may be determined by the order of user input for the first and second induction hobs (8) and (9), or may be fixed as default. For example, when the control unit 20 first receives an operation input for the second induction cooking utensil 9 from the user and then receives an operation input for the first induction cooking utensil 8, the first induction cooking utensil 8 ) may be performed first, or conversely, duty control may be performed first for the second induction burner 9. In addition, when the first induction burner 8 is set to be duty-operated controlled first by default, the control unit 20 performs duty shift control for the first and second induction burners 8 and 9, The first induction burner 8 can be operated on duty first.

In step S7, the control unit 20 adjusts the increased thermal power (P1-1) and (P2-1) by increasing at least one set thermal power (P1) and (P2), and determines the increased thermal power (P1-1). 1), reduce at least one set duty (D1), (D2) so that (P2-1) is equal to the set accumulated power by set fire power (P1), (P2) and set duty (D1), (D2) This is determined by adjusting the reduction duty (D1-1) and (D2-1). In Table 3 above, the thermal power of the first induction burner 8 is increased from 1100W to 1800W, and the duty is adjusted from 6/6 to 3.66/6 so that the set integrated power before changing the heating power and the set integrated power after changing the heating power are the same. Thus, the set integrated power of the first induction burner 8 is maintained constant.

In step S9, the control unit 20 determines whether duty stagger control can be performed based on the reduced duties (D1-1) and (D2-1). If the sum of the reduced duties (D1-1) and (D2-1) is less than or equal to the duty cycle (Dp), the control unit 20 can perform duty-staggering control and proceeds to step S11. Otherwise, Since there is an overlap time between the reduced duties (D1-1) and (D2-1) within the duty cycle (Dp), the process proceeds to step S10.

In step S10, the control unit 20 controls both the first and second relay units (RLY1) and (RLY2) to block so that the capacitance of the first and second induction cooking utensils (8) and (9) becomes the minimum capacitance. After setting and saving the operation history information to the reset state, proceed to (A).

In step S11, the control unit 20 increases the thermal power (P-1) and (P2-1) adjusted in step (S7) and reduces the duty (D1-1) and (D2-1) adjusted in the first step. and begins performing duty stagger control for the second inverter craters (8) and (9).

In step S13, the control unit 20 determines whether a single induction cooker is currently in operation. That is, the control unit 20 performs step S13 because there is no need to perform the interference noise prevention method when only a single induction cooker is operating. If a single induction burner is currently in operation, the process proceeds to step S23. Otherwise, if a plurality of induction burners are currently in operation, the process proceeds to step S15.

In step S15, the control unit 20 receives the cooking vessel inspection results from the first and second driving units 18 and 19 and determines whether the cooking vessel of one or more induction cookers has been removed. For this determination, the first and second driving units 18 and 19 perform a cooking vessel inspection using the difference in current values depending on the presence or absence of the first and second cooking vessels, and send the cooking vessel inspection results to the control unit. This is applied to (20), and the control unit 20 determines whether the cooking vessels placed on the first and second induction burners (8) and (9) have been removed according to the cooking vessel inspection results. If the cooking vessel has been removed from any one of the first and second induction burners (8) and (9), the process proceeds to step S17. Otherwise, the process proceeds to step S19.

In step S17, the control unit 20 calculates the removal duration time of the cooking vessel based on the cooking vessel inspection results from the first and second driving units 18 and 19, and the calculated removal duration time is the standard. Determine whether it is longer than an hour (eg, 1 minute). The first and second driving units 18 and 19 inspect the cooking vessel at a certain period (e.g., 1 second) for a reference time (e.g., 1 minute) based on the current value difference depending on the presence or absence of the cooking vessel. Repeatedly, the cooking vessel inspection results are applied to the control unit 20. If the removal duration of the cooking vessel is longer than the standard, proceed to step S21, otherwise proceed to step S3.

In step S19, the control unit 20 determines whether the heating power of one or more induction cookers has been changed by a user input from the input unit 5 without removing the cooking vessel. If the heating power of any one of the first and second induction burners (8) and (9) is changed, the resonance frequencies of the first and second induction burners (8) and (9) are changed to prevent interference noise. Since it is necessary to re-determine and process whether there is interference between the devices, proceed to step S3 and perform the interference noise prevention method from the beginning. If the thermal powers for the first and second induction burners (8) and (9) have not changed, the process proceeds to step S5 and performs the currently performed duty stagger control.

In step S21, the control unit 20 controls the first or second driving units 18 and 19 to cancel cooking of the induction cooker from which the cooking vessel has been removed so that the heating operation is stopped.

In step S23, the control unit 20 terminates the interference noise prevention method since only one induction cooker is operating, and sets the heating power and duty of the one operating induction cooker to the set heating power (P1) set by the user, ( The first or second driving units 18 and 19 are controlled to maintain or restore the duties (P2) and duties (D1) and (D2).

In step S25, the control unit 20 determines whether cooking of all induction cookers has been completed through input from the user through the input unit 5 or through a previous control process for the first and second driving units 18 and 19. judge. If the first or second induction burners (8) and (9) are in operation, proceed to (a) to allow cooking to proceed; otherwise, proceed to step S27.

In step S27, the control unit 20 controls both the first and second relay units (RLY1) and (RLY2) to be blocked so that the capacitance of the first and second induction burners (8) and (9) is the minimum capacitance. The operation history information is set to a reset state and saved, and the entire control process is terminated.

Table 5 below shows the adjustment process of set fire power and set duty in steps (S3) to (S9) and (S11).

fireball Before changing the setting power After changing the setting firepower Firepower (W) Duty (Sec) Integrated power (Wh) Firepower (W) Duty (Sec) Integrated power (Wh) 1st induction burner (8) 1100W 4.9/6 898 1800W 2.99/6 897 2nd induction burner (9) 1100W 4.9/6 898 1800W 2.99/6 897

When performing step S3, the control unit 20 calculates the sum of the duty (4.9/6) of the first induction burner (8) and the duty (4.9/6) of the second induction burner (9), as shown in Table 5. It is determined that this duty cycle is greater than (6/6), and the process proceeds to step S7. In step S7, the control unit 20 increases the set thermal power of the first and second induction burners 8 and 9 from 1100W to 1800W, and sets the accumulated power (898W) before changing the set heating power and changing the set heating power. After setting, adjust the duty by reducing it from 4.9/6 to 2.99/6 so that the integrated power (897W) is the same or the difference is minimal. In step S9, the control unit 20 determines that the sum of the adjusted reduction duties (2.99/6) and (2.99/6) of the first and second induction burners (8) and (9) is the duty cycle (6/6). ), so it proceeds to step S11 and controls the first and second induction burners (8) and (9) to operate alternately with increased thermal power (1800W) and reduced duty (2.99/6).

In Table 5, before changing the set fire power, the duties of the first and second induction burners (8) and (9) overlap for 3.8 to 4.9 seconds, and interference noise occurs during the overlapping time, but after changing the set fire power, the duties of the first and second induction burners (8) and (9) overlap for 3.8 to 4.9 seconds. Since the duties of the first and second induction burners (8) and (9) do not overlap, no interference noise is generated.

In step S7, the control unit 20 increases the set thermal powers to the maximum adjustable thermal power of the first and second induction burners 8 and 9 and adjusts the set duty, or sequentially increases the set thermal powers by the standard size. Adjust by increasing it, and adjust by decreasing the set duty accordingly.

FIG. 3 is a flowchart of the frequency control process included in the control operation of FIG. 2.

In step S29, the control unit 20 adjusts the increased thermal power (P1-1) and (P2-1) and reduced duty (D1-1) and (D2-1) adjusted in step S7 to step S1. ) Restore and save the previously set fire power (P1), (P2) and set duty (D1), (D2).

In step S31, the control unit 20 operates the plurality of induction burners alternately with set heating powers and set duties to check the resonance frequencies of each of the plurality of induction burners. The control unit 20 drives only the first driving unit 18 to operate only the first induction cooker 8 with a set thermal power (P1) and a set duty (D1) for a certain period of time, and the first driving part 18 operates the first induction cooking unit 8 for a certain period of time. The resonance frequency (f1) of the cooking pot (8) is calculated and transmitted to the control unit (20). Next, the control unit 20 drives only the second driving unit 19 to operate only the second induction cooker 19 for a certain time with a set thermal power (P2) and a set duty (D2), and the second driving unit 19 operates The resonance frequency (f2) of the second induction burner (19) is calculated and transmitted to the control unit (20).

In step S33, the control unit 20 calculates the difference (absolute value) △f between the resonant frequencies f1 and f2 to determine whether interference noise is generated.

In step S35, the control unit 20 compares the difference (absolute value) Δf between the resonance frequencies f1 and f2 with the lowest frequency fam in the audible frequency range (e.g., 2 kHz). to determine whether interference noise occurs. If the difference (absolute value) (△f) between the resonance frequencies (f1) and (f2) is greater than the lowest frequency (fam) of the audible frequency range, the control unit 20 determines that interference noise will occur and (A-1 ), otherwise, it is determined that interference noise will not occur and proceeds to step (S71).

The control unit 20 proceeds to (A-1) to perform a capacitance adjustment process and then proceeds to (A-2) to perform step (S37).

In step S37, the control unit 20 determines the smallest heating power (Pn) and the largest heating power (Px) by comparing the resonance frequencies of the plurality of induction burners. The control unit 20 uses the principle that the heating power decreases as the resonance frequency increases, and among the set heating powers (P1) and (P2) of the first and second induction burners (8) and (9), the resonance frequency is greater. The set fire power of the induction burner (In) is set as fire power (Pn), and the set fire power of the induction burner (Ix), which has a smaller resonance frequency, is set as fire power (Px). In addition, the set duty and set accumulated power of the induction burner (In) are divided into duty (Dn) and set accumulated power (Wn), and the set duty and set accumulated power of the induction burner (Ix) are divided into duty (Dx) and set accumulated power ( Wx) is determined.

In step S39, the control unit 20 compares the thermal power (Pn) with the maximum thermal power (Pmax). Here, the maximum thermal power (Pmax) corresponds to the maximum thermal power that the first and second induction burners (8) and (9) can output. If the thermal power (Pn) is less than the maximum thermal power (Pmax), the process proceeds to step S41. Otherwise, the thermal power (Pn) cannot be increased, so the process proceeds to step S53.

In step S41, the control unit 20 increases the thermal power Pn by a standard amount to calculate and store the adjusted thermal power Pn.

In step S43, the control unit 20 operates the induction burner In with the adjusted heat power Pn and the duty Dn of the induction burner In to obtain, confirm, and store the resonance frequency fv. At this time, the induction burner (Ix) does not operate.

In step S45, the control unit 20 calculates the difference (absolute value) (△fv) between the resonance frequency (fv) and the resonance frequency (fx) of the induction cooker (Ix) to determine whether interference noise is generated. Save.

In step S47, the control unit 20 determines whether the calculated difference (absolute value) (△fv) is smaller than the difference (absolute value) (△f) in step S33. If the calculated difference (absolute value) (△fv) is less than the difference (absolute value) (△f), the heating power increase process in step (S41) is effective and proceed to step (S49). Otherwise, step (S41) Since the fire power increase process of ) is not effective, proceed to step (S51).

In step S49, the control unit 20 determines whether interference noise is generated by comparing the calculated difference (absolute value) (△fv) with the lowest frequency (fam) of the audible frequency range. If the calculated difference (absolute value) (△fv) is greater than the lowest frequency (fam) of the audible frequency range, the control unit 20 performs step (S39) to further increase the adjusted fire power (Pn) since interference noise may occur. ), otherwise, it is determined that interference noise will not occur and proceeds to step (S67).

In step S51, the control unit 20 determines that the heating power increase process in step S41 is ineffective in step S47, and the adjusted heating power in step S41 performed before step S47 ( Pn) is reduced by the standard size and determined by the heating power of the induction burner (In). The thermal power of the induction burner (In) determined in this way has the smallest difference (absolute value) (△fv).

Steps (S39) to (S49) are a process of sequentially increasing the heating power (Pn) of the induction cooking pot (In) by a standard size within the maximum heating power (Pmax) to reduce the resonance frequency (fv) of the induction cooking pot (In). It applies to In step S39, the control unit 20 performs the same operation as the above-described step S39 when proceeding from step S37, and the adjusted thermal power Pn in step S41 when proceeding from step S49. The maximum thermal power (Pmax) is compared, and then, in step S41, a process of additionally increasing the adjusted thermal power (Pn) by the standard size is performed to bring the thermal power (Pn) of the induction burner (In) within the maximum thermal power (Pmax). It increases sequentially by the standard size. Additionally, in step S47, the control unit 20 compares the difference (absolute value) (△fv) and the difference (absolute value) (△f) when proceeding from step S37 to step S47, When proceeding from step S49 to step S47, the difference (absolute value) (△fv) calculated in step S45 and the difference calculated and stored in step S45 before proceeding to step S49 ( By comparing the absolute value (△fv), the process of minimizing the difference (absolute value) (△fv) is performed.

The control unit 20 performs the above-described steps (S39) to (S49) and step (S51) to minimize the difference (absolute value) (△fv) by increasing the heating power (heating power increase process). do.

In step S53, the control unit 20 compares the thermal power (Px) with the minimum thermal power (Pmin). Here, the minimum thermal power (Pmin) corresponds to the minimum thermal power that the first and second induction burners (8) and (9) can output. If the thermal power (Px) is greater than the minimum thermal power (Pmin), proceed to step S55, otherwise proceed to step S67.

In step S55, the control unit 20 reduces the thermal power (Px) by a standard amount to calculate and store the adjusted thermal power (Px).

In step S57, the control unit 20 operates the induction burner (Ix) with the adjusted heat power (Px) and the duty (Dx) of the induction burner (Ix) to obtain, confirm, and store the resonance frequency (fw). At this time, the induction cooker (In) does not operate.

In step S59, the control unit 20 determines whether interference noise is generated by inducing an induction device operated with a resonant frequency (fw) and a thermal power (Pn) and duty (Dn) determined in step S51 or step S37. Calculate and store the difference (absolute value) (△fw) between the resonance frequencies (fv) of the crater (In).

In step S61 or step S37, the control unit 20 determines that the calculated difference (absolute value) (△fw) is the minimized difference (absolute value) (△fv) calculated in steps (S39) to (S51). Determine whether it has decreased. If the calculated difference (absolute value) (△fw) is reduced than the minimized difference (absolute value) (△fv), the heating power reduction process in step (S55) is effective and proceed to step (S63). Otherwise, proceed to step (S63). Since the fire power reduction process in (S55) is ineffective, proceed to step (S65).

In step S63, the control unit 20 determines whether interference noise is generated by comparing the calculated difference (absolute value) (△fw) with the lowest frequency (fam) of the audible frequency range. If the calculated difference (absolute value) (△fw) is greater than the lowest frequency (fam) of the audible frequency range, the control unit 20 performs step S53 to further reduce the adjusted fire power (Px) since interference noise may occur. ), otherwise, it is determined that interference noise will not occur and proceeds to step (S67).

In step S65, the control unit 20 determines that the heating power reduction process in step S55 is ineffective in step S61, and the adjusted heating power in step S55 performed before step S61 ( Px) is increased by the standard size and determined by the heating power of the induction burner (Ix). The thermal power of the induction burner (Ix) determined in this way has the smallest difference (absolute value) (△fw).

Steps (S53) to (S63) are a process of increasing the resonance frequency (fw) of the induction burner (Ix) by sequentially reducing the heating power (Px) of the induction burner (Ix) by a standard size from the minimum heat power (Pmin). It applies to In step S51, the control unit 20 performs the same operation as the above-described step S53 when proceeding from step S53, and the adjusted thermal power (Px) at step S55 when proceeding from step S63. The minimum heating power (Pmin) is compared, and then, in step S55, a process of additionally reducing the adjusted heating power (Px) by the standard size is performed to bring the heating power (Px) of the induction burner (Ix) within the minimum heating power (Pmin). It is sequentially reduced by the standard size. Additionally, in step S61, the control unit 20 compares the difference (absolute value) (△fw) and the minimized difference (absolute value) (△fv) when proceeding from step S51 to step S61. And, when proceeding from step S63 to step S61, the difference (absolute value) (△fw) calculated in step S59 and the difference calculated and stored in step S59 before proceeding to step S63 Compare the difference (absolute value) (△fw) and perform the process of minimizing the difference (absolute value) (△fw).

The control unit 20 performs the above-described steps (S53) to (S63) and step (S65) to minimize the difference (absolute value) (△fv) by reducing the heating power (heating power reduction process). do.

In step S67, the control unit 20 determines that the set accumulated power of the induction burner In and the set accumulated power of the induction burner Ix for which the heating power change process in steps S37 to (S65) were performed are compared to the set accumulated power of the induction burner Ix before the heating power change. The duty (Dn) of the induction burner (In) and the duty (Dn) of the induction burner (Ix) are set to be equal to or close to the set accumulated power (Wn) of the induction burner (In) and the set accumulated power (Wx) of the induction burner (Ix). At least one of Dx) is adjusted so that each of the set integrated power of the induction burner (In) and (Ix) is maintained constant. When proceeding from step S49 to step S67, the duty (Dn) is adjusted based on the adjusted thermal power (Pn) of step (S41) performed before step S49 to be equal to the set accumulated power (Wn). The adjusted heating power (Pn) and duty (Dn) at this time are referred to as the determined heating power (Pn) and duty (Dn) of the induction cooking pot (In), and the heating power (Px) and duty (Dn) of the induction cooking pot (Ix) are referred to as Dx) is referred to as the determined thermal power (Px) and duty (Dx) of the induction burner (Ix).

In addition, when proceeding from step S63 to step S67, the duty (Dn) is adjusted based on the determined thermal power (Pn) of the induction burner (In) in step (S51) to be equal to the set integrated power (Wn). Then, the duty (Dx) is adjusted based on the adjusted thermal power (Px) in step (S57) performed before step (S63) to be equal to the set accumulated power (Wx). At this time, the adjusted duty (Dn) is referred to as the determined duty (Dn) of the induction burner (In), and the adjusted heat power (Px) and duty (Dx) of the induction burner (Ix) are referred to as the determined heat power of the induction burner (Ix). They are referred to as (Px) and duty (Dx).

In addition, when proceeding from step S65 to step S67, the duty Dn is adjusted based on the determined thermal power Pn of the induction burner In in step S51 to be equal to the set integrated power Wn. In step S65, the duty (Dx) is adjusted based on the determined thermal power (Px) of the induction burner (Ix) to be equal to the set integrated power (Wx). At this time, the adjusted duty (Dn) is referred to as the determined duty (Dn) of the induction burner (In), and the adjusted duty (Dx) is referred to as the determined duty (Dx) of the induction burner (Ix).

Through the above-described process, the control unit 20 calculates and stores the determined heating power (Pn) and duty (Dn) of the induction cooking pot (In) and the determined heating power (Px) and duty (Dx) of the induction cooking pot (Ix).

In step S69, the control unit 20 controls the induction burners In and Ix in step S67 with the determined thermal power Pn and duty Dn, respectively, and the determined thermal power Px and duty Dx. ) to operate. Precisely, the control unit 20 controls the first or second induction burners (8) and (9) corresponding to the induction burners (In) and (Ix) determined in step S37, respectively, to the determined heating power (Pn) and duty ( Operate with Dn) and determined fire power (Px) and duty (Dx).

In step S71, the control unit 20 operates a plurality of induction cooking utensils with heating power and duty set by the user. That is, the control unit 20 operates the first and second induction cooking utensils 8 and 9 with the set thermal power (P1) and (P2) and the set duty (D1) and (D2), and at this time, the set duty (D1) Even if ) and (D2) overlap for a certain period of time, interference noise is not generated due to the determination in step (S35).

The heating power increasing process of steps (S39) to (S51) and the heating power decreasing process of steps (S53) to (S65) described above may be performed in a changed order. That is, the heating power reduction process may be performed first and the heating power increasing process may be performed later.

In addition, the control unit 20 preferentially performs the processes of steps (S31), (S33), (S35), and (S71) independently of the duty stagger control process or the frequency change control process, and in step (S35), if If the difference (absolute value) (△f) between the resonance frequencies (f1) and (f2) is greater than the lowest frequency (fam) of the audible frequency range, the control unit 20 determines that interference noise will occur and performs the duty gap control process or A frequency change control process may also be performed.

Additionally, in step S35, the control unit 20 compares the difference (absolute value) △f with the highest frequency of the audible frequency range, and if the difference (absolute value) △f is the highest frequency of the audible frequency range. If the above is the case, proceed to step (S71). Otherwise, you may proceed to (A-1).

In the embodiment of FIG. 3, the control unit 20 increases the heating power of the induction cooking pot (In) with low setting heating power so that the difference (absolute value) (△fv) and (△fw) are below the lowest frequency of the audible frequency range and sets the setting heating power. The process of lowering the heating power of this high induction burner (Ix) is performed. In addition, the control unit 20 sets the thermal power of the induction cooking pot (In) with a low thermal power so that the difference (absolute value) (△fv) and (△fw) is higher than the highest frequency of the audible frequency range (for example, 20 kHz). You can also perform the process of lowering and increasing the heating power of the induction burner (Ix) with high heating power.

In addition, in the case of an induction heating cooker equipped with three or more induction burners, the control and operating principle for the two induction burners in FIG. 3 are the same, but the heating power is adjusted according to the number of added burners and the resonance frequencies are compared. The conditions for doing so increase. In other words, the heating power of the induction cooking zone with the lowest resonance frequency (fmin) of each cooking zone is fixed, the heating power of the remaining induction cooking zones is adjusted by increasing it by the standard size, and the heating power of the remaining induction cooking zones is adjusted according to the lowest resonance frequency (fmin) and the adjusted heating power. A heating power increase process is performed by comparing the resonance frequencies of the induction cooking utensils to determine whether the difference (absolute value) between the resonance frequencies is within the lowest frequency of the audible frequency range. If no interference noise is generated during this process of increasing thermal power, the thermal power reduction process is not performed, and if interference noise is generated, the thermal power reduction process is performed. The heating power reduction process is adjusted by reducing the heating power of the induction cooker with the lowest resonant frequency (fmin) by the standard size, and the resonance frequencies of the induction cookers due to the process of increasing the heating power and the resonance frequencies of the induction cooker with the reduced heating power are adjusted. By comparing each, a fire power reduction process is performed to determine whether the difference (absolute value) between the resonance frequencies is within the lowest frequency of the audible frequency range. In addition, a process of adjusting the duty of each induction burner is performed so that the accumulated power of each induction burner before the interference noise prevention method is performed is satisfied.

For example, if induction cooker 1 has the lowest resonance frequency, induction cooker 3 has the highest resonance frequency, and induction cooker 2 has the middle resonance frequency, the control unit 20 fixes the heating power of induction cooker 1. Then, increase the heating power of induction burners 2 and 3 to the standard size, and the difference (absolute value) between the resonance frequencies of induction burners 1 to 3 (difference between the resonance frequency of induction burner 1 and the resonance frequency of induction burner 2, induction burner 1 Calculate the difference between the resonance frequency of and the resonance frequency of induction cooker 3. The control unit 20 determines that the difference between the resonance frequency of induction cooker 1 and the resonance frequency of induction cooker 2 is within the lowest frequency of the audible frequency range, but the difference between the resonance frequency of induction cooker 1 and the resonance frequency of induction cooker 3 is within the lowest frequency of the audible frequency range. If it exceeds this, the heating power increase process is performed by further increasing the heating power of the induction burner 3 by the standard size. If the heating power of induction cooking zone 2 and induction cooking zone 3 is the maximum thermal power, but interference noise occurs, the heating power reduction process is performed by reducing the heating power of induction cooking zone 1 by the standard size. In this way, the control unit 20 can prevent interference noise even when a plurality of induction cookers are provided.

Additionally, the control unit 20 may adjust the heating power of three or more induction burners so that the difference between the resonance frequencies of the induction burners is greater than or equal to the maximum frequency of the audible frequency range.

FIG. 4 is a flowchart of the capacitance adjustment process included in the control operation of FIG. 2. The single induction burner in operation is one of the first or second induction burner 8 or 9, but in this flow chart, the first induction burner 8 is illustrated as being in operation.

In step S25 of FIG. 2, when the first induction burner 8 is in operation, the process proceeds to step S101 through (a).

In step S101, the control unit 20 controls the operation of the first induction burner 8 at a set heating power and duty.

In step S103, the control unit 20 determines the state (set or reset state) of the stored motion history information and proceeds to step S105 if the motion history information is in the reset state. Otherwise, if the motion history information is in the set state, the control unit 20 determines the state (set or reset state). Proceed to step S113.

In step S105, the control unit 20 sets the operation history information to a set state.

In step S107, the control unit 20 checks the resonance frequency fc of the first induction cooker 8, which is an induction cooker in operation. The control unit 20 operates only the first driving unit 18 to operate the first induction cooker 8 at the lowest thermal power (e.g., level 7 (1100W)) and full duty D1 for a certain period of time. , the first driving unit 18 calculates the resonance frequency (fc) of the first induction cooker 8 and transmits it to the control unit 20. Here, as confirmed in Table 2, since the resonance frequency of the first induction burner 8 at the lowest heat power is higher than the resonance frequency of the first induction burner 8 at the maximum heat power, the first switch ( SW1) has the most severe fever. Therefore, considering that the user can use the lowest thermal power, it is desirable to perform step S107 based on the lowest thermal power.

In step S109, the control unit 20 compares the received resonance frequency (fc) with the reference resonance frequency (Rf) for preventing heat generation. Here, the reference resonance frequency (Rf) corresponds to a frequency (for example, 40 kHz) at which excessive heat generation of the first switch (SW1) occurs. If the received resonance frequency (fc) is greater than the reference resonance frequency (Rf), the control unit 20 determines that the heat generation of the first switch (SW1) may be excessive and the capacitance needs to be varied (increased), so step (S111) Otherwise, the conduction operation control (capacitance variable) of the first relay unit (RLY1) is unnecessary and the process proceeds to step S113.

In step S111, the control unit 20 operates the first relay unit (RLY1), which is a relay included in the first induction cooker 8, which is an induction cooker in operation, in a conducting state to increase the capacitance of the first induction cooker 8. Increase to the maximum capacitance.

In step S113, the control unit 20 controls the operation of the first induction burner 8 at a set heating power and duty.

In step S115, the control unit 20 determines whether cooking of the first induction cooker 8, which is an induction cooker in operation, has ended. If cooking of the first induction burner 8 is completed, proceed to (C) and perform step (S27). Otherwise, proceed to (b) and proceed to step (S1).

The order of performance of the above-described steps (S105) and (S107) may be changed.

In addition, proceeding from step S115 to (b), when only the first induction cooker 8, which is a single induction cooker, is operating in step S1, through steps S25, (a), and step S101. When proceeding to step S103, the control unit 20 checks the stored operation history information and proceeds to step S113 since the operation history information is set to prevent unnecessary repetition of steps S105 to S111. do.

FIG. 5 is a flowchart of the capacitance adjustment process performed in the frequency control process of FIG. 3.

The control unit 20 performs step S35 and proceeds to step S201 through (A-1).

In step S201, the control unit 20 checks the status of the stored operation history information, and if the operation history information is in a reset state, proceeds to step S203 to determine whether capacitance adjustment is necessary. Otherwise, the operation history information is set. If the state (i.e., capacitance adjustment is unnecessary or the capacitance has already been adjusted), the process proceeds to step S37 through (A-2).

In step S203, the control unit 20 compares the difference (absolute value) △f between the resonance frequencies f1 and f2 calculated in step S33 with the reference frequency fac for capacitance adjustment. do. As described above, the capacitance adjustment process reduces the resonance frequency by the variable range of the resonance frequency (e.g., 4 to 6 kHz), so the difference (absolute value) between the calculated resonance frequencies (f1) and (f2) ( When Δf) is greater than or equal to the variable range, the control unit 20 may perform a capacitance adjustment process. Here, the reference frequency (fac) for capacitance adjustment is set to have a frequency included in this variable range, for example, 5 kHz. If the difference (absolute value) (△f) between the calculated resonance frequencies (f1) and (f2) is greater than or equal to the reference frequency (fac), proceed to step (S205). Otherwise, proceed to step (S205) through (A-2). Proceed to S37).

In step S205, the control unit 20 sets the operation history information to a set state and stores it.

In step S207, the control unit 20 compares the resonance frequency f1 of the first induction cooker 8 and the resonance frequency f2 of the second induction cooker 9, and selects the induction cooker having a large resonance frequency. Increase the capacitance from the minimum capacitance to the maximum capacitance. If the resonant frequency f1 of the first induction burner 8 is greater than or equal to the resonant frequency f2 of the second induction burner 9, proceed to step S209, otherwise proceed to step S211. . However, in step S203, if the difference (absolute value) △f between the resonance frequencies (f1) and (f2) is greater than or equal to the variable range, the process proceeds to step S207, so the resonance frequencies (f1) and (f2) ) are not the same.

In step S209, the control unit 20 controls the first relay unit RLY1 to be turned on in order to reduce the resonance frequency f1 of the first induction cooker 8. The capacitance is varied to the maximum capacitance and proceeds to step (S29) through (A).

In step S211, the control unit 20 controls the second relay unit RLY2 to be turned on in order to reduce the resonance frequency f2 of the second induction cooker 9. The capacitance is varied to the maximum capacitance and proceeds to step (S29) through (A).

Unlike the order shown in FIG. 5, the above-described step (S205) may be performed after steps (S209) and (S211), respectively.

3 and 5 described above, the present invention preferentially performs the capacitance adjustment process between (A-1) and (A-2) when interference noise is generated in step S35, so that the first and second After reducing the difference between the resonance frequencies between the induction burners 8 and 9 by the above-described variable range by capacitance adjustment, the frequency control process is exemplarily performed in steps S37 to S69. Although described, the control sequence of the capacitance adjustment process and frequency control process may be changed.

FIG. 6 is a graph explaining the heating amount compensation process performed by the induction heating cooker of FIG. 1. The control unit 20 controls the first and second driving units 18 and 19 so that the first and second driving parts 18 and 19 are connected to the first and second induction burners 8 and 9. Apply fire power according to the set duty (duty ON and OFF). Ideally, the heating power should immediately increase from 0 to the set heating power (W1) at the duty-on time (t1), but the heating power increases as shown in FIG. 6 depending on the time constant value of the circuit components inside the cooking vessel or induction heating cooker. A rising time occurs that gradually increases from 0 to the set fire power (W1). The rising time (t1-t2) in FIG. 6 causes a loss of heating amount (PL - shaded portion). In other words, while performing the interference noise prevention method, a loss of heating amount occurs at each duty-on point, so a difference equal to the heating loss amount (PL) occurs between the set integrated power and the actual integrated power.

In order to solve this problem, the control unit 20 turns off the actual heating power after a certain period of time has elapsed from the point of duty OFF included in the set duty, that is, the first and second induction cooking utensils are compensated for more than the set duty. Compensate for the amount of heating by operating it for more time. Specifically, the control unit 20 obtains the current value from the first and second driving units 18 and 19, and calculates the time (time t2) required for the current value to rise to the target current value corresponding to the set thermal power W1. - Calculate time (t1)), check the current value in regular time units from time (t1) to time (t2), calculate the slope of the current rise curve, and integrate the slope of the current rise curve to determine the amount of heat loss ( PL) is calculated. Next, the control unit 20 calculates the compensation time by dividing the loss heating amount (PL) by the currently set thermal power (W1). In Figure 6, the compensation time (time (t3) to (t4)) is shown, and the control unit 20 maintains the fire power for the compensation time at the duty off point (time (t3)) of the set duty and maintains the fire power at the duty time (t4). An off signal is applied to the first and second driving units 18 and 19. That is, the control unit 20 adds the compensation time to the set duty, and sends the first and second driving units 18 and 19 (on-duty time of the set duty (time (t3) - time (t1)) + compensation) By applying a duty control signal including time) to the first and second driving units 18 and 19, the first and second induction burners 18 and 19 (on duty time (time) of the set duty The heating operation is performed for (t3) - time (t1)) + compensation time). For example, if the on-duty time is 3 seconds and the compensation time is 0.2 seconds, the control unit 20 generates a control signal including the duty (3.2/6) to drive the first and second drivers 18, By applying (19), a compensation process for the amount of heating loss is performed.

As described above, the control unit 20 compensates for the heating amount using the current values from the first and second driving units 18 and 19, but uses other measured values (e.g., voltage values, etc.) Thus, heating amount compensation may be performed.

Alternatively, the induction heating cooker is provided with an integrated power meter that measures the integrated power at the first and second induction burners 8 and 9, and the control unit 20 obtains the integrated power from the integrated power meter. The control unit 20 stores the accumulated power data at the maximum thermal power and the total duty (6/6), receives the accumulated power due to the maximum thermal power and the set duty from the integrated power meter, and calculates the accumulated power included in the stored accumulated power data. The compensation time may be calculated by dividing the difference between the applied integrated powers (integrated power difference) by the maximum thermal power. In addition, the control unit 20 stores controllable heating powers and all integrated power data at the total duty (6/6), receives the set heating power and accumulated power due to the set duty from the integrated power meter, and responds to the stored set heating power. The compensation time may be calculated by dividing the difference between the applied integrated power and the applied integrated power by the set thermal power.

FIG. 7 is a graph illustrating the operation control process of induction cookers performed in the frequency control process performed by the induction heating cooker of FIG. 1.

Figure 7 (a) is a thermal power graph (S1) of the first induction burner 8 operating at the total duty (6/6) and thermal power (Wa), and Figure 7 (b) is the duty at time (t10). This is a thermal power graph (S2) of the second induction cooking utensil (9) in ON operation, and (c) in FIG. 7 is a thermal power graph (S3) of the first induction cooking utensil (8) modified according to the present invention.

By the frequency control process, the thermal power of the first induction cooking pot (8) and/or the thermal power of the second induction cooking pot (9) are adjusted so that the first induction cooking pot (8) is adjusted to the heating power (Wa) and the second induction cooking pot (9) is adjusted. ) is operated with thermal power (Wb), no interference noise is generated. However, due to the rising time (time (t10) to (t11)), the thermal power of the second induction burner 9 gradually increases from 0 to the thermal power (Wb). That is, during the rising time, the resonant frequency of the second induction burner 9 changes, so that the difference (absolute value) between the resonant frequencies of the first and second induction burners 8 and 9 is in the audible frequency range. This causes interference noise.

In order to prevent such interference noise, as shown in (c) of FIG. 7, when the respective duties of a plurality of induction cookers overlap during the operation of duty stagger control or frequency change control, each induction cooker controls the duty. By matching the timing of change from the OFF state to the duty-on state, the frequency change due to the rising time of each induction cooker occurs equally, so that there is little difference between the resonance frequencies of the induction cookers or outside the audible frequency range. Let’s do it. If the first induction hob 8 is at full duty (6/6) and the second induction hob 9 is at the set duty, the control unit 20 operates before the duty ON of the second induction hob 9. At the point where the first induction burner (8) is turned off and the second induction burner (9) is turned on, the first and second induction burners (8) and (9) are turned on. By operating in this state, interference noise due to frequency changes in rising time can be prevented.

As explained above, the present invention is not limited to the above-described specific preferred embodiments, and anyone skilled in the art can use various Of course, modifications are possible, and such modifications fall within the scope of the claims.

1: Power unit 3: Rectifier unit
5: input part 7: display part
8, 9: first and second induction burners 18, 19: first and second driving units
20: Control unit SW1, SW2: First and second switches
RLY1, RLY2: 1st and 2nd relay units

Claims (22)

At least one driving unit that operates at least one induction cooking unit with variable capacitance;
an input unit that obtains a set heating power and a set duty or heating power level for each of the at least one induction cooker from the user;
Each of the at least one driving unit is controlled to operate the at least one induction cooker with the set heating power and set duty or with the set heating power and set duty corresponding to the heating power level, and a single burner among the at least one induction cooker is used. When the induction cooker performs a heating operation, a control unit is provided to check the resonance frequency of the single induction cooker and perform a capacitance adjustment process of varying the capacitance of the single induction cooker based on the confirmed resonance frequency,
The control unit operates the single induction cooker at minimum heating power and full duty, and checks the resonance frequency of the single induction cooker from the driving unit,
Compare the confirmed resonance frequency with the reference resonance frequency to determine the need for varying the capacitance of the single induction cooker,
If the confirmed resonance frequency is greater than the reference resonance frequency, it is determined that the capacitance needs to be changed, and the capacitance of the single induction cooker is varied. delete delete delete a plurality of driving units that respectively operate a plurality of induction cooking utensils with variable capacitance;
an input unit that obtains a set heating power and a set duty or heating power level for each of the plurality of induction cookers from the user;
The plurality of driving units are each controlled to operate the plurality of induction cookers with the set heating power and set duty, or with the set heating power and set duty corresponding to the heating power level, when the plurality of induction cookers perform a heating operation. , the plurality of induction burners are alternately operated at the set heating power and set duty to check the resonance frequencies of the plurality of induction burners from the plurality of driving units, respectively, based on the difference (absolute value) between the resonance frequencies. A control unit that performs a capacitance adjustment process to vary the capacitance of one of the plurality of induction cookers,
When performing a simultaneous heating operation of the plurality of induction burners, the control unit compares the sum of each set duty of the plurality of induction burners and the duty cycle before the capacitance adjustment process to adjust the duty cycle for the plurality of induction burners. An induction heating cooker characterized by performing control. According to claim 5,
The control unit determines the necessity of varying the capacitance by comparing the difference (absolute value) between the resonance frequencies with a reference frequency for capacitance adjustment. According to claim 6,
When the difference (absolute value) between the resonance frequencies is greater than the reference frequency, the control unit determines that the capacitance needs to be changed, and changes the capacitance of one of the plurality of induction cookers. Induction heating cooker. According to claim 7,
An induction heating cooker, wherein the control unit varies the capacitance of an induction cooker having a larger resonance frequency among the resonance frequencies. The method according to any one of claims 1 or 6 to 8,
An induction heating cooker, wherein the control unit stores operation history information indicating whether it has determined the need to vary capacitance for the single induction cooker or the plurality of induction cookers. According to clause 9,
An induction heating cooker, characterized in that the operation history information includes one of a set state or a reset state. According to claim 10,
The control unit determines the necessity of changing the capacitance when the operation history information is in a reset state, and the control unit sets the operation history information to a set state. According to claim 10,
The control unit is configured to vary the capacitance of the at least one induction cooker or the plurality of induction cookers to a minimum capacitance and set the operation history information to a reset state. delete According to claim 5,
When the sum of the set duties of the plurality of induction cookers is less than or equal to the duty cycle, the control unit performs the duty stagger control. According to claim 5,
When the sum of the set duties of the plurality of induction burners is greater than the duty cycle, the control unit decreases the set duty of at least one induction burner among the plurality of induction burners and increases the set fire power of the one induction burner. , An induction heating cooker, characterized in that the set accumulated power of the one induction burner is maintained constant. According to claim 15,
The control unit is an induction heating cooker, characterized in that the sum of the set duty and the reduced set duty of the plurality of induction cookers and the duty cycle are compared. According to claim 16,
When the sum of the set duty and the reduced set duty of the plurality of induction burners is less than or equal to the duty cycle, the control unit controls the set duty of the plurality of induction burners, the reduced set duty and set fire power, and the increased set fire power. An induction heating cooker characterized by performing duty stagger control. According to claim 16,
When the sum of the set duty and the reduced set duty of the plurality of induction burners is greater than the duty cycle, the control unit changes the capacitance of the plurality of induction burners to the minimum capacitance and performs at least one of the capacitance adjustment process and the frequency change control process. An induction heating cooker, characterized in that it performs one or more things. According to claim 18,
The control unit performs a frequency change process of adjusting at least one set heat power of the plurality of induction cookers so that the difference (absolute value) between the resonance frequencies is outside the audible frequency range. Cooking machine. According to claim 19,
In order to ensure that the difference (absolute value) between the resonance frequencies is less than or equal to the lowest frequency of the audible frequency range, the control unit performs an increase process for the set heating power of the induction cooker with the largest resonance frequency and the smallest resonance frequency. An induction heating cooker, characterized in that it performs at least one of the processes of reducing the set thermal power of an induction cooking pot. According to claim 19,
In order to ensure that the difference (absolute value) between the resonance frequencies is greater than or equal to the highest frequency of the audible frequency range, the control unit performs a reduction process for the set heating power of the induction cooker with the largest resonance frequency and the smallest resonance frequency. An induction heating cooker characterized in that it performs at least one of the processes of increasing the setting heating power of an induction cooking pot. According to claim 19,
The control unit is an induction heating cooker characterized in that it adjusts the set duty of the induction cooker whose set heat power is adjusted so that the set accumulated power of the induction cooker whose set heat power is adjusted is maintained constant.

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