Induction heater with power transistor switches - supplying resonant circuit containing heating coil and controlled, current-limiting choke

摘要

The induction heater has the oscillator's induction coil acting as the heating coil for the cooking utensil. A parallel resonant circuit is connected in series with a controlled, current-limiting choke. This series circuit is connected via controlled power switches to a current supply. The switches are opened and closed alternately so that the series circuit is supplied with an alternating current. When the switches are being turned-off this current passes via a shunt path comprising capacitors and diodes. The advantage lies in causing no r.f. interference and in being efficient whilst needing relatively few components.