Reduction of Magnetic Flux Leakage from an Induction Heating Range

In the basic arrangement for an induction heating range consisting of an exciting coil and a cooking vessel, magnetic flux leakage always exists which should be reduced to avoid various harmful effects in practical use. It was found that a cylindrical conducting ring which was set to surround the exciting coil was much more effective for the reduction of the flux leakage than the conventional wire ring. The position and width of the ring were adjusted to give the best reduction effect of flux leakage. The validity of the cylindrical ring was confirmed theoretically by the field analysis based upon the finite element method newly developed to model exterior open regions satisfactorily.