JPS6010318Y2 - induction heating device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an induction heating device suitable for induction heating a cooking pot or the like.

This type of induction heating uses a high-frequency generator that includes a heating coil that performs induction heating, and sends a high-frequency current through the heating coil to inductively heat a cooking pot placed near the heating coil. However, since most conventional pots have only one heating coil, they have the disadvantage that the temperature at the bottom of the pot is not uniform.

That is, as shown in A of FIG. 1, the temperature at the center of the bottom of the pot was lower than that at the periphery.

There are also devices with two heating coils, but each cannot be controlled separately, so they have the same drawbacks as those with one heating coil.

The present invention is based on the above considerations, and is an induction heating device that is equipped with a plurality of heating coils and their control switches so that they can be controlled separately to control the temperature of the bottom of the pot depending on the location. It provides:

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In Fig. 2, reference numeral 1 denotes a housing of the induction heating device, on the top of which an object to be heated such as a cooking pot 2 is fixed and placed, and a material such as heat-resistant glass or porcelain that allows high-frequency magnetic flux to pass through efficiently. A flat insulating plate 3 is provided.

At the bottom of the insulating plate 3, a first heating coil 4 and a second heating coil 5 are arranged concentrically and on the same plane, opposite to the cooking pot 2.
For example, a second heating coil 5 is provided on the outer periphery of the first heating coil 4, and each is connected to a power source 6.

The high frequency magnetic flux generated by the heating coils 4 and 5 is effectively transferred to the cooking pot etc. as shown by the arrow, where the high frequency magnetic flux is converted into thermal energy and can heat the cooking pot 2 etc.

Next, the configuration of the power supply 6 will be explained.

In FIG. 3, 7 is a commercial AC power supply, to which a rectifier circuit 8 configured by connecting four diodes 8a, 8b, 8c, and 8d in a bridge is connected, and a capacitor 9 is connected in parallel with the rectifier circuit 8. , take out the DC power supply Edc,
Furthermore, one end of a reactor 10 is attached to the anode side of the rectifier circuit 8, and the capacitor 9 and reactor 10 constitute a filter that removes high frequency signals (for example, 17 kHz to 50 kHz).

A series circuit of a capacitor 11, a DC power source, a forward diode 12, and a capacitor 13 is connected between the other end of the reactor 10 and the cathode of the rectifier circuit 8.
The heating coil 4 and the switching element 14 are connected to a high frequency generator H1 consisting of a damper diode 16 and a capacitor 18 in parallel with the switching element 14.

Further, connected to the capacitor 13 is a high frequency generator H2 comprising a second heating coil 5, a switching element 15, a damper diode 17 in parallel with the switching element 15, and a capacitor 19.

A gate drive circuit 20.21 (not shown) for supplying a switching signal is provided at the gate of the switching element 14.15.

Note that the capacitors 18 and 19 are connected to the first heating coil 4, respectively.
Together with the inductance of the second heating filter 5, it forms a resonant circuit.

Furthermore, although a so-called GTO (gate turn-off thyristor) is used as the switching elements 14 and 15, a transistor or the like may also be used.

In such a configuration, when commercial alternating current is supplied from the power supply 7, it is converted to direct current by the rectifier circuit 8, and the direct current power Edc is supplied to the capacitors 11 and 13.
By using a capacitor with approximately the same capacitance value as 1.13,
The voltage across the capacitors 11 and 13 is divided to 1/2 EdC.

Here, when a required high frequency signal is supplied from the gate drive circuit 20.21 to the gate of the switching element 14.15, the switching element 14.15 is turned on, and a current flows as shown by the arrow (solid line).

Next, switching element 14.15 is turned off by supplying an off signal from gate drive circuit 20.21.

At this time, the energy stored in the first heating coil 4 and the second heating coil 5 is discharged through the path indicated by the broken line.

By repeating such an operation, a high frequency current can be continuously passed through the first heating coil 4 and the second heating coil 5, and as described above, power can be efficiently supplied to a cooking pot or the like. Can be done.

Furthermore, the diode 12 allows the circuit block that constitutes the first heating coil 4 and the circuit block that constitutes the second heating coil 5 to have independent configurations even though they share a common power source.

As a result of this configuration, the temperature at the bottom of the pot was made almost uniform as shown in B in FIG.

In addition, the first heating coil 4
If the heating coil 5 and the second heating coil 5 are used independently by appropriately switching and adjusting the output, uneven heating can be further eliminated.

As explained above, according to the present invention, since two heating coils and their control switches are provided, the temperature at the bottom of the pot is made uniform, and an induction heating device without uneven heating can be provided.

Incidentally, it is also possible to carry out the same method even if two or more heating coils are provided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between the location of the bottom of the pot and the temperature in the case of one and two heating coils, Fig. 2 is a block diagram of an induction heating device according to an embodiment of the present invention, and Fig. 3 is a diagram showing the relationship between the temperature and the location of the pot bottom in the case of one and two heating coils. It is a circuit diagram. 4...First heating coil, 5...Second
heating coil, 20.21... gate drive circuit,
22゜23... Control switch.

Claims (1)

[Scope of utility model registration request] The other end of a capacitor with a forward diode connected between it is connected to a DC power source, and a high frequency generator consisting of a heating coil, a switching element, its gate drive circuit, etc. is connected to both ends of both capacitors. An induction heating device characterized in that gate drive circuits 20 and 21 are provided with control switches 22 and 23 so that heating coil 4 and heating coil 5 can be controlled separately.