KR101846359B1 - Electric range having multiple working-coils and control method therefor - Google Patents

Abstract

An electric range equipped with a plurality of working coils according to the present invention includes: a first inverter unit; A first hearth having first and second working coils; A second inverter section; A second incinerator having third and fourth working coils; The third fireplace; The control unit controls the connection relationship between the first and second working coils of the first fire wall and the connection relationship between the first fire wall and the third fire wall and controls the connection relationship between the third and fourth working coils of the second fire wall, Wherein the control unit controls the connection relationship between the crater and the third crater and controls the switching frequency of the first switching signal and the second switching signal to be the same at an arbitrary frequency And controlling the output of each of the first to third openings by controlling the on-time pulse width of each cycle constituting each switching signal.

Description

TECHNICAL FIELD [0001] The present invention relates to an electric range equipped with a plurality of working coils,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric range equipped with a plurality of working coils, and more particularly, to an electric range including a plurality of working coils independently driven by independent switching signals and a control method of such an electric range .

There is known an electric range in which energy is applied to the cooking container by an electric power to cause the cooking container to generate heat by itself, thereby cooking the food contained in the cooking container.

On the other hand, an electric range equipped with at least two working coils has been developed in accordance with a user's demand for performing various cooking at the same time.

An electric range having two or more working coils is also designed in such a manner that working coils are grouped and each working coil group is individually supplied with high-frequency power by its own switching circuit.

Thus, in an electric range in which a plurality of working coils are included in each group and each switching circuit is provided for each group, it is necessary to connect the plurality of working coils in an optimal connection manner. That is, the simplicity and the productivity of the circuit configuration and the score of the parts to be consumed can be changed depending on how a plurality of working coils are included in one group.

Further, when the plurality of working coils operate independently by the respective switching circuits, the frequencies of the switching signals interfere with each other, and audible noise may be generated. Therefore, a control method for minimizing such noise is required.

An object of the present invention is to improve the simplicity and productivity of a circuit configuration and to minimize the number of parts required by connecting a plurality of culverts constituting one group by an optimal connection method.

Another object of the present invention is to provide a control method for efficiently removing audible noise that may occur when different switching circuits operate respective working coils.

Another object of the present invention is to provide a control method capable of controlling the output of each working coil as desired even in a state where audible noise is suppressed.

According to an aspect of the present invention, there is provided an electric range equipped with a plurality of working coils for switching a direct current power according to an input first switching signal to output a first high frequency power between a first end and a second end A first inverter section; And a first working coil and a second working coil, wherein the first working coil and the second working coil are configured as nodes between the first end and the second end, or the first and second working coils are connected between the first end and the second end in series A first furnace configured to couple only one of the first and second working coils between the first end and the second end; A second inverter unit for switching the DC power according to an input second switching signal to output a second high frequency power between a third stage and a fourth stage; A third working coil and a fourth working coil, and a node between the third stage and the fourth stage is formed as a node, or between the third stage and the fourth stage, the third and fourth working coils are connected in series Or a second incinerator configured to be able to engage only one of the third and fourth working coils between the third stage and the fourth stage; A third hearth including at least one working coil connected between the first and the second end and connected to or between the second and the fourth end; The control unit controls the connection relationship between the first and second working coils and the connection relationship between the first and third fireboxes in the first fireplace and provides the first switching signal to the first inverter unit, Controls the heating operation of the third fireplace, controls the connection relationship of the third and fourth working coils and the connection relation of the second and third fireboxes in the second fireplace, and controls the connection of the second switching signal To control the heating operation of the second and third openers, and at least when the first and second inverter units are operated simultaneously, the switching frequency of the first and second switching signals is maintained at an arbitrary same frequency And controlling the output of each of the first to third openings by controlling the on-time pulse width of each cycle constituting each switching signal.

Here, the first incinerator includes the first working coil and the second working coil connected in series to each other; A first selecting end coupled to one end of the first working coil and a second selecting end coupled to a connecting point between the first working coil and the second working coil, relay; And a second relay having a first selection stage coupled to the connection point, a second selection stage coupled to the other end of the second working coil, and a fixed stage, wherein: The third working coil and the fourth working coil connected to each other; A third selecting coil having a fixed end coupled to the first end, a first selection end coupled to one end of the third working coil, and a second selection end coupled to a connection point between the third working coil and the fourth working coil, relay; And a fourth relay having a first select end coupled to the connection point, a second select end coupled to the other end of the fourth working coil, and a fixed end, A fifth relay having a fixed end coupled to a fixed end of the second relay, a first selected end coupled to the second end, and a second selected end coupled to one end of the third working coil; A sixth relay having a fixed end coupled to a fixed end of the fourth relay, a first selected end coupled to one end of the fifth working coil, and a second selected end coupled to the fourth end; And a seventh relay having a fixed end coupled to the other end of the fifth working coil, a first selected end coupled to the second end, and a second selected end coupled to the fourth end.

In another configuration, the first fire wall includes the first working coil and the second working coil connected in series with each other; A first relay having one fixed end, a first selection end coupled to one end of the first working coil, and a second selection end coupled to a connection point of the first working coil and the second working coil; And a second relay having a first selection stage coupled to the connection point, a second selection stage coupled to the other end of the second working coil, and a fixed stage coupled to the second stage, The crater includes the third working coil and the fourth working coil connected in series with each other; A third relay having one fixed end, a first selection end coupled to one end of the third working coil, and a second selection end coupled to a connection point of the third working coil and the fourth working coil; And a fourth relay having a first selection stage coupled to the connection point, a second selection stage coupled to the other end of the fourth working coil, and a fixed stage coupled to the fourth stage, A third relay having a fixed end coupled to the first end, a first selected end coupled to the fixed end of the first relay, and a second selected end coupled to one end of the fifth working coil; A sixth relay having a fixed end coupled to the third end, a first selected end coupled to one end of the fifth working coil, and a second selected end coupled to a fixed end of the third relay; And a seventh relay having a fixed end coupled to the other end of the fifth working coil, a first selected end coupled to the second end, and a second selected end coupled to the fourth end, .

Further, the first inverter unit may include: an upper switching device having an input terminal for receiving the DC power, an output terminal connected to the working coil, and a control terminal to which an upper switching signal is applied; A half bridge resonance system or a full bridge resonance system including an input connected to the output terminal of the upper switching element, an output terminal connected to the ground, and a lower switching element having a control terminal to which a lower switching signal is applied, The first switching signal controls ON / OFF of the upper switching element in each cycle of the switching frequency. The first switching signal controls ON / OFF of the upper switching signal whose on-time pulse width is controlled, And at this time, the lower switching signal can be kept off during at least the on time of the upper switching signal.

In addition, in the case where only one of the first and second openings is operated, the first and third openings are simultaneously operated, or the second and third openings are simultaneously operated, It is possible to control the output of the crane to be operated by changing the frequency of the switching signal provided to the crane.

According to the electric range according to the present invention having the above-described configuration, a plurality of working coils are connected in series and the relays are arranged in parallel, so that a desired working coil can be selectively operated. The circuit configuration for connecting the working coil is simple, and the number of parts required can be reduced.

Further, according to the present invention, even if a plurality of working coil groups operate simultaneously, no audible noise due to frequency interference of the switching signal is generated.

Further, in a state in which the audible noise is suppressed, the output of each working coil group operating at the same time can be arbitrarily controlled.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a circuit structure of an electric range provided with a plurality of working coils according to an embodiment of the present invention; FIG.
2 is a view showing a working coil connection structure of an electric range with five working coils according to an embodiment of the present invention.
3 is a view showing a working coil connection structure of an electric range with five working coils according to another embodiment of the present invention.
Fig. 4 is a view showing an example of disposing a plurality of culverts including a plurality of working coils. Fig.
5 is a waveform diagram of a switching signal for explaining a general method of controlling the output of each fire wall in an electric range equipped with a plurality of independently controlled fireworks.
6 is a waveform diagram of a switching signal for explaining a method of controlling the output of each firebox when a plurality of fireplaces that can be controlled independently are simultaneously operated in an electric range equipped with a plurality of working coils according to the present invention to be.
FIG. 7 is a flowchart of a method for controlling switching signals of respective craters in an electric range equipped with a plurality of working coils according to the present invention.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of an electric range including a plurality of working coils and a control method thereof according to various embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting.

First, a structure of an electric range including a plurality of working coils according to an embodiment of the present invention will be described with reference to a schematic circuit diagram of FIG. Referring to the drawings, an electric range according to the present invention includes a first DC power generating unit 10 and a second DC power generating unit 17 for receiving DC power from a commercial power source and generating DC power required in the electric range, ; A first inverter unit 31 for switching the DC power from the first DC power generating unit 10 according to the input first switching signal and outputting the first high frequency power; A second inverter unit 32 for switching the DC power from the second DC power generating unit 17 according to the inputted second switching signal and outputting the second high frequency power; A first furnace (20) including a plurality of working coils connected in series and operated by a first high frequency power from a first inverter section (31); A second furnace (26) comprising at least one working coil and operated by a second high frequency power from a second inverter section (32); A first switching signal is provided to the first inverter unit 31 to induce heating by using at least one working coil of the first furnace 20 and to provide a second switching signal to the second inverter unit 32 And a control unit (50) for causing at least one working coil of the second fire wall (26) to perform induction heating so as to simultaneously operate the two fire polo.

In the present invention, it is possible to operate in accordance with the control of the first inverter unit in series with the first fire wall, or to operate by the second inverter unit in series with the second fire wall, And a third crater that can be operated independently by the control of the two-inverter section, but the illustration is omitted in Fig. This third fireplace will be described with reference to Fig. 2 and Fig.

The first DC power generating unit 10 and the second DC power generating unit 17 may be connected to the commercial power as independent components and can be independently controlled in operation.

The first inverter unit 31 and the second inverter unit 32 switch the DC power from the DC power generation units 10 and 17 according to a predetermined switching frequency to generate high frequency power, Can be supplied to a working coil (or a crater). Each DC power generating portion includes respective switching elements, and the switching operation of the switching elements can be controlled by an input switching signal.

The first inverter unit 31 includes a half bridge resonance system in which at least two switching elements QH and QL are connected in series and whose connection point is an output terminal, or a pair of switching elements (not shown) And the first high frequency power is outputted to the working coil by controlling the operation of each switching element. In the present invention, a circuit is constituted and controlled by a half bridge resonance method will be described as an example.

Here, among the series-connected switching elements, the (+) voltage side switching element of DC power is called an upper switching element, and the (-) voltage side switching element of DC power is called a lower switching element.

The configuration of the second inverter unit 32 may be the same as that of the first inverter unit 31 and outputs a second high frequency power to at least two switching elements.

At this time, the output side of the first inverter unit 31 constitutes the first stage 11 and the ground side constitutes the second stage 12. At least one working coil is connected between the first stage 11 and the second stage 12 (i.e., a first furnace and / or a third furnace), and the working coil is connected to the first inverter unit 31 The induction heating is performed by the output.

Likewise, the output side of the second inverter section 32 constitutes the third stage 13, and the ground side constitutes the fourth stage 14. Another working coil is connected between the third stage 13 and the fourth stage 14 to induce heating by the output of the second inverter section 32 (i.e., the second and / or the third furnace) .

The first fire wall 20 and the second fire wall 26 may each include at least one working coil. The first fire wall 20 may have two working coils, which are connected in series and coupled between the first end 11 and the second end 12. Each working coil is coupled through a plurality of relays between a first stage and a second stage, and can be solely coupled or simultaneously (coupled in series) between the first stage and the second stage by controlling the state of each relay have.

The second fire wall 26 also has two working coils and may be coupled in series between the third stage 13 and the fourth stage 14. Similarly, the second fire wall also includes a plurality of relays, and the state of engagement of the respective working coils can be changed by the state of each relay.

The control unit 50 provides the first inverter unit 31 with a first switching signal so that the first inverter unit 31 can supply the first high frequency power to the first crater 20. At the same time, the control unit 50 controls at least one of the plurality of relays of the first fire wall 20 so that at least one of the plurality of working coils included in the first fire wall 20 performs induction heating by the first high- .

Also, the control unit 50 can perform the same control on the second inverter unit 32 and the second fire wall 26. [ That is, the state of each of the plurality of relays constituting the second fire wall is controlled, and at least one working coil included in the second fire wall 26 is supplied to the second inverter section 32 by induction heating .

By simultaneously controlling the first inverter unit 31 and the second inverter unit 32 simultaneously, the two working coils (first and second craters) can be operated at the same time, So that two kinds of cooking can be performed simultaneously.

On the other hand, in the electric range according to the present invention, a desired working coil can be selectively operated by combining a plurality of working coils constituting each fire wall in an improved connection manner. Various connection methods will be described with reference to Figs. 2 to 3. Fig.

2 is a view showing a working coil connection structure of an electric range with five working coils according to an embodiment of the present invention.

The first crater 20 and the third crater 27 can be coupled between the first stage 11 and the second stage 12 to which the first high frequency power is supplied by the first inverter unit 31 .

First, the first fire wall 20 includes first and second working coils 21 and 22, a first relay R1 and a second relay R2.

The first working coil 21 and the second working coil 22 are connected in series with each other. Each of the working coils has one end and the other end, and the other end of the first working coil 21 and one end of the second working coil 22 are connected to each other by a series connection.

The first relay R1 includes a first selecting end connected to the first end 11 and a fixed end coupled to one end of the first working coil 21 and a second selecting coil connected between the first working coil 21 and the second working coil 22). ≪ / RTI >

The second relay R2 has a first selected end coupled to the connection point of the first working coil 21 and the second working coil 22 and a second selected end coupled to the other end of the second working coil 22 , And one fixed end.

In this structure, by controlling the selected ends of the first relay (R1) and the second relay (R2), the first crushing chamber (20) is in a state in which only the first working coil (21) 22 are selected, and both the first and second working coils 21, 22 are selected.

The second fire wall 26 is the same as the connection relationship of the first fire wall 20, and therefore, reference is made to the drawings.

The third fire wall 27 includes fifth, sixth and seventh relays R5, R6 and R7, and a fifth working coil 25.

The fifth relay R5 has a fixed end coupled to the fixed end of the second relay R2, a first selected end coupled to the second end 12, a third end coupled to one end of the third working coil 23, 2 selection stage.

The sixth relay R6 has a fixed end coupled to the fixed end of the fourth relay R4, a first selected end coupled to one end of the fifth working coil 25, a second end coupled to the fourth end 14, 2 selection stage.

The seventh relay R7 has a fixed end coupled to the other end of the fifth working coil 25, a first selected end coupled to the second end 12, a second selected end coupled to the fourth end 14, Respectively.

In this connection structure, as each relay is controlled, the second relay R2 is coupled to the second end, or the fifth working coil 25 is connected between the first end 11 and the second end 12 Or the fourth relay R4 may be coupled to the fourth stage 14 or the fifth working coil 25 may be coupled between the third stage 13 and the fourth stage 14. [ . This allows the fifth working coil 25 to be operated depending on the first or second crater (connected in series), operated alone, or not operated.

3 is a view showing a working coil connection structure of an electric range with five working coils according to another embodiment of the present invention.

The construction of the first fire wall 20 and the second fire wall 26 is the same as that of FIG.

On the other hand, in this embodiment, the third fire wall 27 is constituted as follows.

The fifth relay R5 has a fixed end coupled to the first end, a first selected end coupled to the fixed end of the first relay R1, a second selected end coupled to one end of the fifth working coil 25, Respectively.

The sixth relay R6 has a fixed end coupled to the third stage 13, a first selected end coupled to one end of the fifth working coil 25, a second selected end coupled to one end of the fifth working coil 25, And a selection stage.

The seventh relay R7 has a fixed end coupled to the other end of the fifth working coil 25, a first selected end coupled to the second end 12, a second selected end coupled to the fourth end 14, .

In this configuration, by controlling the states of the fifth relay R5, the sixth relay R6, and the seventh relay R7, the fifth working coil 25 is connected to the first stage 11 and the second stage 12 or coupled between the third stage 13 and the fourth stage 14. In this way,

Fig. 4 is a view showing an example of arranging a plurality of culverts including a plurality of working coils connected in the same manner as the above-described embodiment in an electric range. The upper surface of the electric range is usually composed of a flat upper plate 28. The working coil for performing the induction heating can be disposed below the upper plate 28, and the upper plate 28 can visually display a region (heating region) corresponding to the shape and position of the working coil. The user can place the cooking container or the cooking object on the heating area and start induction heating.

For example, a plurality of concentric circles may be displayed on the upper plate, and working coils may be disposed on the respective concentric circles to constitute the small-scale heating regions 21, 22, 23, 24, and 25. Since each working coil can be arranged in each small heating area, the reference numerals are used in combination. The arranged order of the respective working coils can be set arbitrarily.

In particular, the first to fifth working coils may be arranged in order from the center of the concentric circle to the outside. If the user uses a very small cooking vessel, the heating operation can be started by operating only the first working coil 21 through a predetermined operation function. The second to fifth working coils 22, 23, 24, and 25 may be sequentially selected and operated in accordance with an increase in size or shape of the cooking vessel.

Alternatively, when cooking is started, the control unit 50 operates all of the five working coils 21, 22, 23, 24, and 25, identifies a working coil in which induction heating is performed among the working coils, It is possible to control the relay operation of the working coil except for the coil (the working coil not participating in the induction heating) so that the power is supplied only to the working coil for performing the induction heating so as to perform the heating operation with the optimum efficiency.

When the user selects the heating output of the first stage, only the first working coil 21 is operated. When the user selects the second stage, the first and second heating coils 21 and 22 are simultaneously operated, The third to fifth heating coils may be sequentially operated by selecting the third step, the fourth step or the fifth step.

On the other hand, as described above, in the electric range equipped with a plurality of burners, the first burner 20 is controlled by the first direct-current power generation unit 10 and the first inverter unit 31, 26 are independently controlled by the second DC power generating unit 17 and the second inverter unit 32, there is a possibility that audible noise may be generated due to the interference of the respective switching signals due to the operation of the respective inverter units.

In a typical electric range, the induction heating output of the working coil is adjusted by changing the frequency of the upper / lower switching signal applied to the upper / lower switching element.

For example, referring to the waveform diagram of FIG. 5, in the case where the induction heating output is controlled by the frequency control method, the frequencies of the first upper switching signal and the first lower switching signal constituting the first switching signal are controlled by the controller 50 ) Will be described.

5 (a) shows that the first switching signal is formed at a frequency of 45 kHz, for example. The first upper switching signal and the first lower switching signal are shown together. Each cycle may include one on-time and one off-time.

During the on time of the first upper switching signal, the first lower switching signal must be off-time.

Here, the first switching signal may be operated at a frequency of 45 kHz, and the induction heating output of the first fire wall 20 may be 400 W at this time.

5 (b) shows that the first switching signal is formed at a frequency of 23 kHz, for example. When the first switching signal is 23 kHz, for example, the induction heating output of the first fire wall 20 may be 1800 W. As the on time width of the first switching signal decreases, the energy delivered by the resonance decreases, so that the induction heating output is reduced.

5 (c) shows that the first switching signal is formed at a frequency of 50 kHz, for example. When the first switching signal is 50 kHz, for example, the induction heating output of the first fire wall 20 may be 300 W.

Thus, by increasing or decreasing the frequency of the switching signal, it is possible to adjust the output of the induction heating through the working coil included in the furnace. Lowering this switching frequency may increase the output of the induction heating, but lowering the switching frequency to the audible frequency range may cause noise during switching operation and cause problems such as heat generation of the working coil itself. Thus, the switching frequency is adjusted above the audible frequency range.

On the other hand, the high (or on-time) of the upper switching signal and the high of the lower switching signal have a predetermined time difference (i.e., a dead time). This is because the upper switching device and the lower switching device can be turned on at the same time .

In this way, the induction heating output is controlled in such a manner that the switching frequency applied to the working coils of the first fire wall 20 and the switching frequency of the switching signal applied to the second fire wall 26 are changed independently of each other The frequencies of the switching signals interfere with each other to generate an interference sound, which may be an unpleasant noise.

Particularly, every time the output of each crater is changed, the noise becomes larger or smaller, which causes unpleasant feeling to use.

Therefore, in the present invention, when a plurality of culverts are to be operated simultaneously, the frequency of the switching signals applied to the respective culverts are kept the same, and the output is adjusted by controlling the width of the on- .

6 is a waveform diagram for explaining this control method. 6 is an example of a switching signal having the same frequency in the electric range according to the present invention. As shown in FIG. 6, the ON time within one cycle of the upper switching signal and the lower switching signal constituting the first switching signal is controlled The control method proposed by the present invention. In particular, it is desirable to control the on-time of the upper switching signal.

6 (a) shows an example of a first switching signal having a switching frequency of, for example, 21 kHz. In the present invention, the second switching signal will also have the same frequency. However, the on time of the upper switching signal of the second switching signal may be the same as or different from the waveform shown in the figure.

On the other hand, in the induction heating circuit of the half bridge current resonance method or full bridge resonance method, the actual induction heating output is controlled by the operation of the upper switching element, and the operation of the lower switching element is almost independent of the output. Accordingly, in the present invention, the on-time of the upper switching element is mainly controlled, and the on-time of the lower switching element is controlled depending on the on-time of the upper switching element. Lt; / RTI >

Figure 6 (a) shows that the on-time pulse width D1 is 50% at a fixed frequency of 21 kHz (this 50% may include dead time). The basic switching signal is based on a normal sine wave. And can safely operate at maximum output when the on-time is 50% within one period. The output in the illustrated example may be, for example, 1800W.

When the output of the first fire wall 20 is to be reduced during the maximum output as described above, the frequency of the switching signal is not increased, but, as shown in FIG. 6 (b) The pulse width of the on-time is decreased. It can be seen that the on-time pulse width D2 is considerably reduced even in the waveform diagram. The output at this time may be, for example, 400W.

Since the on time of the first upper switching signal is reduced in this way, the off time of the first switching device Q1 may be longer. At this time, the on time of the first lower switching signal can be arbitrarily determined within the off time range of the first upper switching signal.

By reducing the on time of the first upper switching signal, the high frequency current applied to the first fire wall 20 is reduced, and as a result, the output of induction heating is reduced.

6 (c) shows a case in which the output of the first fire wall 20 is further reduced. In the waveform diagram, the on time (D3) of the first upper switching signal is further reduced, and the output at this time may be 300W.

The second switching signal for controlling the second inverter unit 32 during the on-time control in the state where the switching frequency of the first switching signal is kept constant (for example, 21 kHz) While maintaining the frequency at 21 kHz, it can be controlled by increasing or decreasing the pulse width of the on-time to match the induction heating output.

Since the switching frequency of the first switching signal and the second switching signal is always the same even when the output of the second fire wall is controlled, no noise due to the interference due to the different resonance frequency is generated.

On the other hand, the same frequency can be arbitrarily selected from among frequencies capable of maintaining safety even when a plurality of craters are operated simultaneously.

That is, the induction heating output of the currently operating crater is measured, and the optimum heating performance is provided based on the type, size, shape or position of the cooking container, the number of induction heating output steps set by the user, A frequency that can ensure the safe operation of each component constituting the electric range can be selected.

Next, a control method for operating a plurality of inverter circuits at the same frequency in the electric range according to the present invention will be described with reference to the flowchart of Fig.

First, the user can start cooking using one cullet (S110). At this time, since the control unit 50 is in a state in which only a single crater is operated, the induction heating output can be adjusted by changing the frequency of the switching signal for each of the upper and lower switching elements of the inverter unit that controls the crater ( S170).

Of course, even when only one crater is operated, the output of the induction heating is adjusted in such a manner that the on-time pulse width constituting one cycle of the switching signal is controlled in a state in which the frequency is fixed to an arbitrary value Control is also possible.

On the other hand, if the user further intends to use more than one crane (S130), the control unit 50 fixes the frequency of the switching signal provided to the crane during the previous operation to a predetermined frequency, The frequency of the switching signal to be provided to the inverter is also used to generate a switching signal using the same fixed frequency, and provides the switching signal to the inverter unit for controlling the crane to be added. Then, by controlling the on-time pulse width constituting one period of the switching signal in accordance with the requested output to each fire wall, the output for each screen is controlled (S140).

Here, the same fixed frequency can be arbitrarily selected according to the current operating state of each crater. Further, the same frequency to be fixed may not be completely fixed but may be changed as needed, either increasing or decreasing. Of course, the frequencies of the switching signals applied to the respective inverter sections must be changed at the same time.

The embodiments of the present invention described above are merely illustrative of the technical idea of the present invention, and the scope of protection of the present invention should be interpreted according to the claims. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the essential characteristics thereof, It is to be understood that the invention is not limited thereto.

Claims (5)

A first inverter unit for switching a DC power according to an input first switching signal to output a first high frequency power between a first end and a second end;
And a first working coil and a second working coil, wherein the first working coil and the second working coil are configured as nodes between the first end and the second end, or the first and second working coils are connected between the first end and the second end in series A first furnace configured to couple only one of the first and second working coils between the first end and the second end;
A second inverter unit for switching the DC power according to an input second switching signal to output a second high frequency power between a third stage and a fourth stage;
A third working coil and a fourth working coil, and a node between the third stage and the fourth stage is formed as a node, or between the third stage and the fourth stage, the third and fourth working coils are connected in series Or a second incinerator configured to be able to engage only one of the third and fourth working coils between the third stage and the fourth stage;
A third hearth including at least one working coil connected between the first and the second end and connected to or between the second and the fourth end;
The control unit controls the connection relationship between the first and second working coils and the connection relationship between the first and third fireboxes in the first fireplace and provides the first switching signal to the first inverter unit, Controls the heating operation of the third fireplace, controls the connection relationship of the third and fourth working coils and the connection relation of the second and third fireboxes in the second fireplace, and controls the connection of the second switching signal To control the heating operation of the second and third openers, and at least when the first and second inverter units are operated simultaneously, the switching frequency of the first and second switching signals is maintained at an arbitrary same frequency And a control unit for controlling an output of each of the first to third openings by controlling an on-time pulse width of each cycle constituting each switching signal. The method according to claim 1,
The first crater includes:
The first working coil and the second working coil connected to each other in series;
A first selecting end coupled to one end of the first working coil and a second selecting end coupled to a connecting point between the first working coil and the second working coil, relay; And
And a second relay having a first selected end coupled to the connection point, a second selected end coupled to the other end of the second working coil, and a fixed end,
The second crater includes:
The third working coil and the fourth working coil connected in series to each other;
A third selecting coil having a fixed end coupled to the first end, a first selection end coupled to one end of the third working coil, and a second selection end coupled to a connection point between the third working coil and the fourth working coil, relay; And
And a fourth relay having a first select end coupled to the connection point, a second select end coupled to the other end of the fourth working coil, and a fixed end,
The third crater includes:
A fifth relay having a fixed end coupled to a fixed end of the second relay, a first selected end coupled to the second end, and a second selected end coupled to one end of the third working coil;
A sixth relay having a fixed end coupled to the fixed end of the fourth relay, a first selected end coupled to one end of the fifth working coil, and a second selected end coupled to the fourth end; And
And a seventh relay having a fixed end coupled to the other end of the fifth working coil, a first selected end coupled to the second end, and a second selected end coupled to the fourth end, An electric range equipped with a plurality of working coils. The method according to claim 1,
The first crater includes:
The first working coil and the second working coil connected to each other in series;
A first relay having one fixed end, a first selection end coupled to one end of the first working coil, and a second selection end coupled to a connection point of the first working coil and the second working coil; And
And a second relay having a first selection stage coupled to the connection point, a second selection stage coupled to the other end of the second working coil, and a fixed stage coupled to the second stage,
The second crater includes:
The third working coil and the fourth working coil connected in series to each other;
A third relay having one fixed end, a first selection end coupled to one end of the third working coil, and a second selection end coupled to a connection point of the third working coil and the fourth working coil; And
And a fourth relay having a first select end coupled to the connection point, a second select end coupled to the other end of the fourth working coil, and a fixed end coupled to the fourth end,
The third crater includes:
A fifth relay having a fixed end coupled to the first end, a first select end coupled to the fixed end of the first relay, and a second select end coupled to one end of the fifth working coil;
A sixth relay having a fixed end coupled to the third end, a first selected end coupled to one end of the fifth working coil, and a second selected end coupled to a fixed end of the third relay; And
And a seventh relay having a fixed end coupled to the other end of the fifth working coil, a first selected end coupled to the second end, and a second selected end coupled to the fourth end, An electric range equipped with a plurality of working coils. The method according to claim 1,
The first inverter unit includes:
An upper switching element having an input terminal for receiving the DC power, an output terminal connected to the working coil, and a control terminal to which an upper switching signal is applied;
And a lower switching element having an input connected to an output terminal of the upper switching element, an output terminal connected to the ground, and a control terminal to which a lower switching signal is applied, the half bridge resonance system or the full bridge resonance system,
Further, the first switching signal may include:
Wherein the control circuit controls the on / off state of the upper switching element in each cycle of the switching frequency,
And wherein the lower switching signal is kept off during at least an on time of the upper switching signal, wherein the lower switching signal is turned on or off. 5. The method of claim 4,
In the case where only one of the first and second openings is operated or the first and third openings are operated simultaneously or the second and third openings are simultaneously operated, Wherein the control unit controls the output of the crane to be operated by changing the frequency of the provided switching signal.

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