Radiated and conducted interferences in induction heating equipment: characteristics and remedies

The authors describe all the disturbances resulting from induction heating equipment, and practical methods to deal with the problems in order that induction heating processes can handle disturbances by themselves, and be made more cost-effective. After a great number of measurements and a study of industrial installations, principal mechanisms of the interferences have been revealed. For harmonic distortion, useful solutions have been proposed, some of which are industrially tested or used by manufacturers. The proposed dual Steinmetz Bridge can thoroughly resolve both the capacitor switching problem and harmonic amplification in a nonlinear load or in a polluted network. A current type inverter is realized in `spread´ type for the high frequency study. On the basis of interference mechanisms, practical solutions such as damping reactor, common mode current bypass, and nonlinear snubber have been proposed and confirmed in a `compacted´ type inverter. The best way for attenuating the interferences is to dispose at sources and transform them into thermal energy