JPS6220291A - Electromagnetic cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an electromagnetic cooker that heats a cooking container by induction heating.

(b) Conventional technology In conventional cooking devices of this type, a so-called inverter is used, in which a DC power source is connected to the induction heating coil via a resonant capacitor, and both ends of the resonant capacitor are switched at high speed using a switching transistor or the like. circuit is used.

(c) Problems to be solved by the invention However, in an electromagnetic cooker using such an inverter circuit, when the material and dimensions of the cooking container used change, the equivalent value of the induction heating coil equipped with the cooking container changes. There have been problems such as changes in inductance and resistance, resulting in changes in the control characteristics of the electromagnetic cooker, and in some cases, increased loss in the switching elements of the inverter circuit.

This invention was made in view of these circumstances, and compensates for changes in the equivalent inductance and resistance of the induction heating coil by changing the capacitance ω of the resonant capacitor to increase or decrease it, thereby keeping the inverter circuit always under the optimum conditions. The present invention provides an electromagnetic cooker that is driven by

(d) Means for Solving the Problems This invention provides an electromagnetic cooker that heats a magnetic cooking container using an induction heating coil, which includes a series circuit of an induction heating coil and a resonant capacitor connected to both ends of a DC power source. , and a switching circuit connected in parallel to the resonant capacitor, and the resonant capacitor has one -L capacitors connected in parallel in a separable manner.

(E) Effect Even if the resonant frequency of the series resonant circuit of the induction heating coil and resonant capacitor changes due to changes in the inductance of the induction heating coil, the resonant frequency is maintained at the optimum value by adjusting the capacitance of the resonant capacitor with a parallel capacitor. be done. Therefore, even if the material of the cooking container placed on the induction heating coil changes, the inverter circuit of the electromagnetic cooker is driven under optimal conditions.

(f) Examples Hereinafter, the present invention will be described in detail based on examples shown in the drawings. Note that this invention is not limited to this.

In Figure 1, (1) is a rectifying and smoothing circuit, (2) is an AC input power supply, (1-) is an induction heating coil, (C1) (C2
) is a resonant capacitor, (S) is a switch, (3) is a switching circuit consisting of a diode (D) and a transistor (T), and (4) is a drive circuit that drives the transistor (T>) in high-speed switching. The circuit is configured.

In the inverter circuit with such a configuration, when the transistor (T) is driven by the drive circuit (4) and supplies a resonant current to the induction heating coil ([) and the capacitor (C1), the induction heating coil (L) is placed thereon. A heated cooking container (not shown) is heated by electromagnetic induction.

By the way, electromagnetic cookers are generally designed for standard iron cooking containers.

However, for example, stainless steel (SUS IL-1
0), the inductance of the induction heating coil (L) is equivalently reduced. In such a case, by closing the switch (S) and connecting a capacitor (C2) in parallel with the resonant capacitor (C1), the induction heating coil (1-) and the capacitor (CI) (C
The resonant circuit constant consisting of 2> is compensated in the same way as when using an iron pot.

In this way, even if the material of the cooking container used changes, the inverter circuit is always driven under equivalently the same conditions, so the control characteristics of the induction cooker and the loss of the switching elements will not be affected. do not have.

In this example, (CI) (
Although two resonant capacitors of C2> are used, it is also possible to connect resonant capacitors of various capacitances in parallel to these capacitors in order to respond more precisely to changes in the material and dimensions of the cooking steel used.

(g) Effects of the Invention According to this invention, even if the material and dimensions of the cooking container used are different, the change in the inductance of the induction heating coil that is affected by this is compensated for by the increase or decrease in the capacitance of the resonant capacitor. Therefore, the inverter circuit of the electromagnetic cooker is driven under almost the same circuit conditions, and its control characteristics and loss of switching elements are maintained at optimum values.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing one embodiment of the present invention. (1)... Rectifier smoothing circuit, (2)...
...AC power supply, (3)...Switching circuit,
(L)...Induction heating coil, (C1) (C2>...Resonance capacitor, (S)
······switch.

Claims (1)

[Scope of Claims] 1. In an electromagnetic cooker that heats a magnetic cooking container with an induction heating coil, a series circuit of an induction heating coil and a resonant capacitor connected to both ends of a DC power source, and a series circuit connected to the resonant capacitor in parallel. 1. An electromagnetic cooking device characterized in that the resonant capacitor has one or more capacitors connected in parallel in a separable manner.