JPH07230878A - Electric power supply for electromagnetic cooking appliance - Google Patents

Abstract

PURPOSE:To provide electric power supply for an electromagnetic cooking appliance suitable for cooking of a highly viscous cooking object, particularly for uniform heating of a cooking object at low electric power heating time. CONSTITUTION:Electric power supply is composed of an inverter part 12 to generate high frequency electric power and a load switching part 17 to control output of the inverter part 12 through a power control part 16. The load switching part 17 alternately switches electric connection between taps S1 and S2 to output DC voltages having different values and the power control part 16 in an optionally adjusted time ratio, and changes electric power outputted from the inverter part 12 in a pulse shape, and supplies it to a heating coil 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a part for an electromagnetic cooker, and more particularly to a power supply for an electromagnetic cooker for adjusting the intensity of induction heating of an object to be heated.

[0002]

2. Description of the Related Art An electromagnetic cooker is provided with a heating coil and a power source inside, and a top plate is arranged on the side of the heating coil on the object to be heated, and high frequency power is supplied from the power source to the heating coil. The object to be heated on the top plate is induction-heated. In this case, the strength of induction heating is
It is uniquely determined by the level of high frequency power supplied from the power source (hereinafter referred to as power level). Therefore, conventionally, when it was necessary to change the intensity of induction heating, this was achieved by adjusting the power level continuously output from the power source as needed.

[0003]

However, in an electromagnetic cooker having a conventional power source, when induction heating is continued at a constant electric power level, various heating points of the object to be heated are constant. There was a problem. For example, when a cooking pot is used as the object to be heated and a highly viscous food such as curry or stew is heated, heat convection does not easily occur inside the food, and uniform heating becomes difficult. Further, depending on the type of cooked food, charring tends to occur. This tendency is particularly remarkable in low-power heating called "melting fire heating", and improvement has been demanded. An object of the present invention is to provide a power supply for an electromagnetic cooker having a configuration capable of solving such a problem.

[0004]

According to a first aspect of the present invention, there is provided an electromagnetic cooker power supply for supplying high frequency power to a heating coil of an electromagnetic cooker, wherein the high frequency power level is cyclically at least two levels. And a time ratio adjusting unit for adjusting the ratio of the power supply time at each stage level in one cycle.

The power source for an electromagnetic cooker according to the second aspect of the invention is a power source for an electromagnetic cooker that supplies high-frequency power to a heating coil of an electromagnetic cooker, by intermittently blocking the output of the high-frequency power to intermittently generate high-frequency power. It has a power control means for supplying electric power to the heating coil, and a time ratio adjusting means for adjusting a time ratio between the supply time and the supply blocking time of the high frequency power in one cycle.

In the power source for the electromagnetic cooker according to the first or second aspect of the invention, the time ratio adjusting means makes one allocation period constant and makes the other allocation periods variable in each cycle, and the allocation period is set to the above-mentioned allocation period. It is also possible to adopt a configuration in which the power supply time or the power supply blocking time is assigned.

[0007]

In the power source for the electromagnetic cooker according to the first aspect of the present invention, the power control means switches the level of high frequency power between maximum and minimum, and supplies it to the heating coil. At that time, the time ratio adjusting means adjusts the maximum and minimum power supply time ratios in one cycle. When the maximum high-frequency power is supplied to the heating coil, the object to be heated, for example, the cooking pot, is more strongly induction-heated in response to this power. Then, when the power level is switched to the minimum, the induction heating intensity of the cooking pot suddenly weakens. As a result of this being repeated periodically, the thermal convection of the cooked food in the pan is promoted while suppressing the average power. The power level of the high frequency power may be periodically changed in three or more steps and supplied to the heating coil. In this case, the thermal convection is repeated according to each step.

In the power source for an electromagnetic cooker according to the second aspect of the invention, the power control means blocks the supply of high frequency power at the time ratio adjusted by the time ratio adjusting means. As a result, high frequency power is intermittently supplied to the heating coil. Therefore, the thermal convection is promoted as in the first invention. Moreover, even if the supplied high frequency power is temporarily maximized, the average power does not rise, so that unnecessary induction heating is suppressed.

Further, the time ratio adjusting means contributes to the adjustment of the power supply time ratio or the supply blocking time of each level of the power level as described above, but one allocation period in each cycle is fixed, Make other allocation periods variable,
When the power supply time or the supply blocking time is allocated to each allocation period, the above-mentioned cycle also becomes variable.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram of a power supply for an electromagnetic cooker according to a first embodiment of the present invention.
0 is an input unit, 11 is a DC power supply unit, 12 is an inverter unit,
Reference numeral 13 is a series resonance capacitor, 14 is a heating coil of an electromagnetic cooker, 15 is a high-frequency current detection coil, 16 is a power control unit, and 17 is a load switching unit. It should be noted that FIG. 1 shows a configuration diagram of only a portion for carrying out the present invention.

In the power source for the electromagnetic cooker having this structure, first, commercial AC power is input from the input section 10 to the DC power source section 11,
Here, rectification and smoothing are performed to generate DC power. Further, this DC power is switched by the inverter unit 12 to be converted into high frequency power having a predetermined frequency, the phase of which is adjusted by the series resonance capacitor 13 and supplied to the heating coil 14. A general-purpose small-sized inverter unit can be used for the inverter unit 12. The high frequency current detection coil 15 detects a current flowing through a high frequency circuit including the inverter unit 12, the capacitor 13, and the heating coil 14, and guides the current to the power control unit 16.

The power control unit 16 controls the switching circuit provided in the inverter unit 12 on the basis of the detected current to make the power level output from the inverter unit 12 constant and to direct the direct current from the load switching unit 17. The power level is changed stepwise according to the voltage value (power control means).

The load switching section 17 includes three loads connected in series to the DC circuit, for example, resistors R1 to R3, taps S1 and S2 provided between the resistors R1 to R3, and taps S1. A switch circuit 171 that alternately and periodically switches electrical connection with S2 at a predetermined time ratio to introduce a DC voltage of a corresponding value to the power control unit 16, and a timing adjustment that adjusts the switching timing of the switch circuit 171. And a circuit 172 (time ratio adjusting means). Since this configuration is for explaining the principle, the type and number of loads may be arbitrary. Also,
The resistors R1 and / or the resistors R2 can also be variable resistors.

In this load switching unit 17, tap S1
Let V1 be the DC voltage value generated at 1, the DC voltage value generated at tap S2 be V2, and the resistance value of each resistor be R1 << R2,
Each DC voltage value is V1 >> V2. Therefore, each tap S
1, S2 and the power control section 16 are electrically switched by the switch circuit 171 alternately at the time ratio adjusted by the timing adjustment circuit 172, so that the inverter section 12 controlled by the switch circuit 171 changes the electrical connection as shown in FIG. As shown, the first high frequency power W1 having the maximum power level and the second high frequency power W2 having the minimum power level are periodically output at an adjusted time ratio.

Therefore, the strength of the high-frequency magnetic field generated in the heating coil 14 changes stepwise and cyclically according to the level of electric power supplied, and when the cooked material is put in the object to be heated, for example, the cooking pot. In addition, it is possible to cause appropriate heat convection in the cooked product while suppressing the overall average power. When adjusting the power switching timing as shown in FIG. 3, the total T of the period (time) Ta assigned to the output of the first power W1 and the period Tb assigned to the output of the second power W2 is set to be constant. You may change the ratio of both, or
One of the allocation periods may be fixed and the other allocation period may be variable. In the latter case, since the cycle itself is variable, the strength of the high-frequency magnetic field generated in the heating coil 14 can be adjusted more multilaterally.

In particular, in the above-mentioned configuration in which the allocation period Ta is fixed and the allocation period Tb is variable, by adjusting Ta << Tb, the power level of the first power W1 is further increased while suppressing an increase in average power. Can be large. Therefore, for example, even when cooking a high-viscosity cooked food such as curry or stew by heating on a simmer, it is possible to surely cause thermal convection and prevent burning.

The above description is an example of changing the high frequency power in two steps, but it may be changed in three steps or more. In this case, in the configuration of FIG. 1, the number of loads of the load switching unit 17 and the number of taps in between are increased, and the load is periodically switched in a predetermined order. In this way, the strength of the high frequency magnetic field generated in the heating coil 14 can be adjusted more finely according to the cooking application.

(Second Embodiment) FIG. 2 is a block diagram of a power supply for an electromagnetic cooker according to a second embodiment of the present invention. Since this embodiment is a modification of the first embodiment described above,
Parts that are the same as the parts shown in FIG.

In this embodiment, an opening / closing control unit 27 is provided in place of the load switching unit 17 of the first embodiment described above. The switching control unit 27 inserts and connects a switch 271 in series with an electric path for supplying a DC voltage of a predetermined value to the power control unit 16, and a timing adjustment circuit that adjusts the timing of the switching control of the switch 271. 272 is provided (time ratio adjusting means).

In this switching control section 27, the switching device 27
The DC voltage is intermittently introduced to the power control unit 16 by periodically opening and closing 1 at a predetermined time ratio. As a result, the output power of the inverter unit 12 is periodically blocked. For example, the pulse-shaped high frequency power is periodically supplied to the heating coil 14 by minimizing the time ratio of closing the electric path. A high-frequency magnetic field is generated in the heating coil 14 only while the high-frequency power is supplied, and the object to be heated, such as a cooking pot, is induction-heated. Therefore, as in the case of the first embodiment, when the food is put in the cooking pot, it is possible to cause an appropriate heat convection while suppressing the average electric power of the whole. In particular, when the power supply time is allocated to an extremely short time, the power level of the high frequency power used can be further increased while suppressing the increase of the average power, so that a cooked food with high viscosity such as curry or stew can be used. Even when the simmering fire is heated, it is possible to surely cause the heat convection and effectively prevent the burning.

Also in this embodiment, the timing control section 272 changes the ratio between the power supply time and the power supply blocking time in one cycle when the switching control of the switch 271 is controlled. Alternatively, one of the times (allocation period) may be constant and the other time may be variable. In the latter case, since the intermittent period is also variable, the strength of the high frequency magnetic field generated in the heating coil 14 can be adjusted more multilaterally.

In particular, in a configuration in which the power supply time is constant and the supply blocking time is variable, the former time is made extremely short, and the power level of the high frequency power used is further suppressed while suppressing the increase in average power. Can be large. Therefore, for example, even when cooking a high-viscosity cooked food such as curry or stew by heating on a simmer, it is possible to surely cause thermal convection and prevent burning.

[0024]

As is apparent from the above description, according to the power source for the electromagnetic cooker of the first invention, the power level of the high frequency power supplied to the heating coil is switched to at least two levels, and each level in one cycle. It is possible to strengthen the high frequency magnetic field of the heating coil stepwise, and in some cases instantaneously, by adjusting the ratio of the power supply time of the heating coil. The problem can be resolved. For example, even in the case of heating a highly viscous food such as curry or stew, it is possible to moderately promote heat convection and perform uniform heating, and the charring thereof is effectively prevented. effective.

Further, according to the power source for the electromagnetic cooker of the second invention, the above effect can be obtained only by periodically blocking the supply of the high frequency power to the heating coil, so that the power source having a simple structure can be realized. Also, it is advantageous in terms of cost.

Further, in the power source for the electromagnetic cooker of each invention, the time ratio adjusting means makes one allocation period constant and the other allocation period variable, and the above-mentioned power supply time or supply interruption time is set in each of these allocation periods. In the configuration of assigning, the cycle itself is also variable, and there is an effect that the strength of the high frequency magnetic field generated in the heating coil can be adjusted in multiple ways.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a power source for an electromagnetic cooker according to a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a power source for an electromagnetic cooker according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an example of power switching timing in the first embodiment.

[Explanation of symbols]

 10 Input Section 11 DC Power Supply Section 12 Inverter Section 13 Series Resonance Capacitor 14 Electromagnetic Cooker Heating Coil 15 High Frequency Current Detection Coil 16 Power Control Section 17 Load Switching Section 171 Switch Circuit 172 Timing Adjustment Circuit 27 Opening and Closing Control Section 271 Switch 272 Timing adjustment circuit

Claims (3)

[Claims] 1. An electromagnetic cooker power supply for supplying high frequency power to a heating coil of an electromagnetic cooker, the power control means for periodically switching the level of the high frequency power to at least two levels and supplying the heating coil. A power supply for an electromagnetic cooker, comprising: a time ratio adjusting means for adjusting a ratio of power supply time at each level of a cycle. 2. An electric power source for an electromagnetic cooker for supplying high frequency power to a heating coil of an electromagnetic cooker, the power control means for periodically interrupting the supply of the high frequency power and supplying intermittent high frequency power to the heating coil. And a time ratio adjusting means for adjusting the time ratio between the power supply time and the supply blocking time in one cycle. 3. The power source for an electromagnetic cooker according to claim 1, wherein the time ratio adjusting means makes one allocation period constant and makes another allocation period variable in each cycle, and each of these allocation periods is changed. A power source for an electromagnetic cooker, wherein the power supply time or the supply blocking time is assigned.