JPH05190268A - Electromagnetic induction heating device for multiport range - Google Patents

Abstract

(57) [Abstract] [Purpose] A plurality of induction heating coils in an electromagnetic induction heating apparatus for a multi-port range can be fed by one inverter, and the heating apparatus is downsized. [Structure] A plurality of induction heating coils in an electromagnetic induction heating apparatus for a multi-port range are connected in series or in parallel, and an appropriate value of impedance ratio is selected to set a power sharing ratio between the heating coils to a predetermined value. Further, the impedance of each heating coil is controlled so that the variation range of the circuit total impedance by each heating coil is within a predetermined variation range specified for stable operation of the inverter, when connected in series or in parallel.
A dance is selected so that the required electric power of each heating coil is simultaneously supplied by one inverter, and when the heating coils are connected in series, the heating coils are opened and closed in parallel with each of the heating coils. On the other hand, when connected in parallel, an opening / closing means for opening the heating coil is provided in series with each heating coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pot which is supplied with a high frequency power from an inverter and which generates an eddy current at the bottom of a metal pot placed on the top plate by the electromagnetic induction effect of the current flowing therethrough. The present invention relates to an electromagnetic induction heating device for a multi-port range, such as an electromagnetic cooker for business use, which includes a plurality of heating coils for heating.

[0002]

2. Description of the Related Art In a conventional electromagnetic induction heating apparatus for a multi-port range having a plurality of heating coils of this type, the same number of inverters as the plurality of heating coils are provided, and each heating coil is provided with a corresponding inverter. -It is known that the power supply is controlled individually by the power supply.

[0003]

However, in the conventional electromagnetic induction heating apparatus for a multiple mouth range as described above,
Since the required number of heating coils and the same number of inverters are provided, the device as a whole must be large and expensive. In view of this, it is an object of the present invention to provide an electromagnetic induction heating device for a multi-port range in which a plurality of heating coils can be simultaneously fed by a single inverter so as to be compact and inexpensive. To do.

[0004]

In order to achieve the above object, an electromagnetic induction heating apparatus for a multi-port range according to the present invention is a metal pan placed on a top plate by an electromagnetic induction action by its energizing current. Coil for heating the metal pot by generating an eddy current at the bottom of the container and an invertor using the heating coil as a load
In an electromagnetic induction heating device comprising a plurality of heating coils as described above, it is for a multiple opening range having a plurality of heating coils as described above, and the required power of each of the plurality of heating coils is simultaneously supplied by one inverter. Also, regarding the plurality of heating coils, these are connected in series or in parallel and the power sharing ratio between the respective heating coils is set to a predetermined value by selecting an appropriate value of the impedance ratio, and either of the series or parallel. When connecting the
It is assumed that the impedance of each heating coil is selected so that the variation range of the dance is within a predetermined variation range specified for stable operation of the inverter, and that when the heating coils are connected in series, An opening / closing means for short-circuiting is provided in parallel with each heating coil, and an opening / closing means for opening the circuit is provided in series with each heating coil when connected in parallel, and further the terminal voltage of each heating coil or Display means for detecting the energizing current and the detection level of the terminal voltage or the energizing current corresponding to the power supplied to each heating coil upon receiving the output signal of the detecting means, and the display installed at an appropriate position for operating the apparatus. Means shall be provided.

[0005]

In order for the inverter to operate stably, it is necessary to operate the inverter so that the output voltage, the output current, and the output power of the inverter do not exceed respective predetermined limit values. FIG. 4 is an operational characteristic diagram showing the safe operating region of the inverter when the load impedance changes, wherein the output voltage is V _o its upper limit value is V _om , and the output current is I _o its upper limit value is I _{o. om} , the output power is P, and the safe operation area when the maximum output power, which is its upper limit value, is P _m is shown by the hatched portion in the figure. Here, the ratio of the voltage V _{o to} the current I _o indicates the output impedance of the inverter, and the straight lines A and B shown in the figure have slopes respectively corresponding to the stable operating range of the inverter. It is an impedance characteristic line corresponding to the maximum value and the minimum value of the output impedance.

Therefore, regardless of whether the required number of power supply loads is single or plural, the impedance characteristic line of the total load of the inverter is located in the hatched portion between the characteristic lines A and B in the figure. If so, stable operation becomes possible. According to the present invention, according to the above, while the plurality of induction heating coils are connected in series or in parallel, the total impedance characteristic line is the above-mentioned characteristic lines A,
By setting the impedance ratio between the respective heating coils so that the power sharing ratio between the respective heating coils is a predetermined value, it is possible to use a single inverter. Power is supplied to the heating coil at a predetermined power distribution ratio at the same time.

The impedance of the circuit formed by the plurality of heating coils changes depending on the change in the number of series or parallel heating coils or the presence / absence of each of the metal pans according to the change in the required heating state. The input power P _e of each heating coil obtained as the distribution value of the output power P is expressed by the following equation (1), and δ (cm) indicating the penetration depth of the induced current at the bottom of the metal pot is It becomes like the following formula (2).

P _e = K · [f · μ · δ] ^1/2 · (N · I) ² …………………… (1) δ = 5.03 × 10 ³ · [ρ / (μ · f )] ^1/2 …………………… (2) where ρ is the specific electric resistance (μΩ · cm), μ is the relative permeability, f is the frequency (H _Z ), and N is the number of turns of the heating coil. (T), I
Is a current flowing through the heating coil (A), and K is a constant depending on the shapes of the heating coil and the metal pot and the relative relationship between the two.

As shown in the above equation (1), the input power P _e of each coil which defines the heating power of each heating coil is proportional to the square of the number of turns N thereof. The self-inductance of each heating coil, and hence its impedance, also changes in proportion to the square of the number of turns N. Therefore, the number of turns of each heating coil is such that the required electric power P _e can be obtained in each heating coil, the power sharing ratio between the heating coils is a predetermined value, and the combined impedance of the heating coils is It is determined by three conditions that the variation range of the dance is between the characteristic lines A and B.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the present invention will be described below with reference to the circuit diagram of the electromagnetic induction heating apparatus for multiple mouth range shown in FIGS. In addition, in each of the drawings, the same display symbols are attached to components having the same function. First, FIG. 1 shows a first embodiment of the present invention in which three sets of heating coils are connected in series and the level of the heating input in each heating coil is displayed. In FIG. 1, reference numeral 1 is an example of an inverter whose load is a series resonance circuit, which is composed of a series resonance capacitor C _r for the total reactance of the load heating coil and a main circuit switching transistor T _r. It is a thing.

Further, 2 and 3 and 4 are heating coils which are spiral plate coils and are connected in series with each other, and the number of coil turns thereof is, for example, 10T, 7T, 5 respectively.
A large-capacity heating coil, a medium-capacity heating coil, and a small-capacity heating coil which are selected as T and have the above-mentioned electric power sharing ratio of about 4: 2: 1 are shown. Further, the composite impedance of each heating coil changes depending on the change in the number of heating coils connected in series due to the change in the required heating state or the presence / absence of a metal pot placed, and the variation range between the maximum value and the minimum value is as shown in FIG. Are selected so as to be located between the characteristic lines A and B.

Reference numerals 30 and 31 and 32 denote a large-sized metal pot, a medium-sized metal pot, and a small-sized metal pot which are heated in correspondence with the heating coils 2 and 3 and 4, respectively. It is placed on the plate 5. Furthermore, 10 and 11 and 1
Reference numeral 2 is a display unit, and the coil voltage corresponding to the input power in the heating coils 2, 3 and 4 is detected by the differential amplifier OA, and the LED for the level meter is turned on by the detection signal to detect the coil voltage. The heating state in the heating coil is displayed. The LEDs are installed in a place convenient for operating the heating device, for example, on the operation touch panel.

Next, FIG. 2 shows a second embodiment of the present invention.
The figure shows a case where three sets of heating coils are connected in series and two sets of heating coils in the three sets can be selectively short-circuited in accordance with changes in the heating state such as a decrease in the number of metal pans. That is, FIG. 2 shows an arrangement in which elements for selectively short-circuiting the heating coils 3 and 4 are provided in place of the display units 10, 11 and 12 in FIG. 1, and SW ₁ and SW ₂ correspond to the heating coils 3 and 4, respectively. Short circuit switch, 40 and 41 are switches C for switching operation
The switches SW ₁ and SW ₂ are respectively operated according to the OS operation command.
It is a heating mode switching section that opens and closes. In addition, the reactor L and the short-circuiting switch SW ₃ are connected in series by the switch S.
The switch SW ₃ is connected in parallel with the switch W ₁ and the switch SW ₃ is closed by a command from the switching unit 40.
_The heating coil 3 is short-circuited instead of ₁ , and the switch is a current limiting circuit which is applied when a sudden increase in the load current is expected due to a sudden decrease in the load circuit overall impedance when the heating coil 3 is short-circuited. It is not used together with SW ₁ .

Further, FIG. 3 shows a third embodiment of the present invention,
The two sets of heating coils provided corresponding to the two sets of metal pans are connected in parallel, and one set of the two heating coils is selectively opened according to the change in the required heating state, and both the heating coils are connected. This is a case where the level of each heating input is displayed. That is, FIG. 3 shows a case where the heating coils 2 and 3 are connected in parallel and only the coil 3 is opened by the opening switch SW ₄ . The switch S
W ₄ is selectively opened / closed by a command from the switching operation switch COS in the switching / display unit 51. Also CT
Reference numerals ₁ and CT ₂ are current transformers for detecting the energizing currents of the heating coils 2 and 3, respectively, and the outputs of both current transformers are for detecting the current level in the display unit 50 and the switching / display unit 51, respectively. It is input to the differential amplifier OA, and the detection signals of the both differential amplifiers are level meters of the both display units 50 and 51, respectively.
The heating LED is turned on to display the heating state of the corresponding heating coils. The output of the differential amplifier OA in the switching / display unit 51 is further input to the comparator CP, and when the energizing current of the heating coil 3 becomes larger than the predetermined value, the comparator CP emits the output. Buffer amplifier B
By driving the switch COS via A, the switch SW ₄ is opened, and the heating coil 3 is disconnected to avoid the overload state of the inverter.

[0015]

According to the present invention, in an electromagnetic induction heating apparatus for a multiple opening range, which comprises a plurality of induction heating coils and an inverter having the heating coils as a load, the plurality of heating coils are provided. Connect in series or in parallel and
The power distribution ratio between the heating coils is set to a predetermined value by selecting an appropriate value of the dance ratio, and the variation range of the circuit overall impedance by the heating coils is set to the above-mentioned invariant when the series or parallel connection is made. -The impedance of each heating coil is selected so that the heating coil is within a predetermined fluctuation range specified for stable operation, and when the heating coils are connected in series, the heating coils are short-circuited in parallel. On the other hand, when the parallel connection is provided, the opening and closing means for opening the heating coil is provided in series with each of the heating coils, and the required power of each of the plurality of heating coils is simultaneously supplied by one inverter. Furthermore, the terminal voltage or the energizing current of each heating coil is detected, and the state of the terminal voltage or the energizing current corresponding to the power supplied to each heating coil is displayed. In addition, the circuit configuration of the electromagnetic induction heating device for the multiple mouth range can be simplified and the size can be greatly reduced. In addition, diversification of cooking and safety of operation of the device can be achieved by selecting and combining pots to be heated. It can also be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an electromagnetic induction heating device for a multiple-port range showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an electromagnetic induction heating device for a multiple-port range showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an electromagnetic induction heating device for a multi-port range showing a third embodiment of the present invention.

FIG. 4 is an operational characteristic diagram showing the safe operating area of the inverter.

[Explanation of symbols]

1 Inverter for heating 2 Large capacity heating coil 3 Medium capacity heating coil 4 Small capacity heating coil 5 Top plate 10 Display section 11 Display section 12 Display section 30 Large metal pan 31 Medium metal pan 32 Small metal pan 40 heating mode - de switching unit 41 heating mode - de switching unit 50 display unit 51 switching and display unit BA buffer amplifier COS changeover operation switch CP comparator C _r series resonant capacitor CT ₁ current transformer CT ₂ current transformer L reactor LED (light emitting diode) OA differential amplifier SW _i switch (for heating coil short circuit or open circuit, i
= 1,2,3,4) _Tr switching transistor

Claims (6)

[Claims] 1. A heating coil for heating the metal pan by generating an eddy current at the bottom of the metal pan placed on the top plate by the electromagnetic induction effect of the energizing current, and an invertor using the heating coil as a load. -In an electromagnetic induction heating device comprising: a plurality of heating coils as described above, for a multi-port range, the required power of each of the plurality of heating coils is simultaneously fed by a single inverter, An electromagnetic induction heating apparatus for a multi-port range, which is configured to simultaneously heat a plurality of metal pans placed corresponding to the respective heating coils. 2. The electromagnetic induction heating apparatus for a multiple opening range according to claim 1, wherein the plurality of heating coils are connected in series and the power sharing ratio between the respective heating coils is selected by selecting an appropriate impedance ratio. Is set to a predetermined value, and the impedance of each heating coil is set so that the variation range of the total impedance of the series connection circuit of each heating coil is within the predetermined variation range specified for stable operation of the inverter. An electromagnetic induction heating device for a multi-port range, which has been selected. 3. The electromagnetic induction heating apparatus for a multiple opening range according to claim 1, wherein the plurality of heating coils are connected in parallel and the power sharing ratio between the heating coils is selected by selecting an appropriate impedance ratio. Is set to a predetermined value, and the impedance of each heating coil is set so that the variation range of the total impedance of the parallel connection circuit of each heating coil is within the predetermined variation range specified for stable operation of the inverter. An electromagnetic induction heating device for a multi-port range, which has been selected. 4. The electromagnetic induction heating apparatus for a multiple opening range according to claim 2, wherein the heating coil short-circuit opening / closing means is provided in parallel with each of the plurality of heating coils connected in series. Electromagnetic induction heating device for multiple mouth range. 5. The electromagnetic induction heating apparatus for a multiple opening range according to claim 3, wherein each of the plurality of heating coils connected in parallel is provided with an opening / closing means for opening the heating coil in series. Electromagnetic induction heating device for multiple mouth range. 6. The electromagnetic induction heating apparatus for a multiple opening range according to claim 1 or 2, wherein each of the heating coils has a terminal voltage or energization current detection means and an output signal of the detection means. Electromagnetic induction for a multiple opening range, characterized in that it has a display means for displaying the detection level of the terminal voltage or energization current corresponding to the power supplied to the heating coil and installed at an appropriate position for operating the apparatus. Heating device.