Matsushita Electric Industrial Co., Ltd.

Tadao Toyooka

Keizo Amagami

Hideyuki Kominami

Takao Kobayashi

Mitsuyuki Kiuchi

Shigeru Kusunoki

Takumi Mizukawa

Hiroshi Fujieda

Yukio Hirai

Masatatsu Nakamura

An induction heating apparatus includes a saturable reactor having a pair of rectangular ferrite cores. An air gap is provided in each ferrite core to provide a gradually increasing saturation characteristic on the magnetization curve of the cores. A pair of series-connected load windings is coiled around each core and a control winding is coiled around a common magnetic path of the cores. A power control circuit produces a DC control current that passes through the control winding. The high frequency energization current is passed through the load windings. Means are provided to control the DC control current at a desired setting. Preferably, the actual power level is detected to control the DC current through a feedback loop.

Induction heating apparatus using a saturable reactor for power control

Electromagnetic coupling between a pan or utensil load to be heated by magnetic induction and a source of high frequency magnetic flux is sensed by detecting a current which is indicative of the electromagnetic coupling by means of a current transformer. The detected current is compared with a reference level. Intermittent generation of the magnetic flux is commenced when, for example, a small magnetic metal object is inadvertently placed as a load with the result that the detected current becomes lower than the reference level. This allows intermittent check for the presence and absence of the inadvertently placed load for subsequent cooking operations and minimization of the heat generated therein.

Pan detector for induction heating apparatus

A high frequency heating apparatus in which a combination of a microwave oven for heating food through dielectric heating and a cooking device for heating metallic vessel through electrical induction is incorporated to effect efficient cooking and simultaneous formation of brown scorching on the surface of food. In the heating apparatus, power required for the magnetron of the microwave oven and also for the heating coil of the cooking device is supplied through one inverter unit, by which arrangement, an efficient cooking apparatus of compact size is presented.

High frequency heating apparatus

A pan detector for an induction heating apparatus of the type having an induction heating coil adapted to electromagnetically couple to a cooking vessel comprises a first, vertically movable magnet and a second, fixed magnet spaced therefrom and a reed switch disposed between the first and second magnets. Upon the placement of a cooking vessel of magnetic metal in overlying relation to the heating coil, the first magnet moves upwardy by attraction between the bottom wall of the cooking vessel and the first magnet to result in a change in magnetic flux level in the neighborhood of the reed switch. The reed switch operates in response to the change in magnetic flux level to permit and prevent, respectively, energization of the heating coil. The first and second magnets have their poles oriented in opposition to each other to provide repulsion therebetwen to increase the attraction.

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Kadoma, Japan

Tadao Toyooka