Induction heating circuits for cooking appliances

(19)

(11)

EP 0 269 413 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	11.01.1989 Bulletin 1989/02

(43)	Date of publication A2:
	01.06.1988 Bulletin 1988/22

(21)	Application number: 87310357.6

(22)	Date of filing: 24.11.1987

(51)	International Patent Classification (IPC)⁴: H05B 6/12, H05B 6/06

(84)	Designated Contracting States:
	BE DE ES FR GB IT NL

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Priority:

25.11.1986 GB 8628098

(71)	Applicant: CREDA LIMITED
	Stoke-on-Trent Staffordshire, ST11 9LJ (GB)

(72)	Inventor:
	Bullough, Robert Ian Fetcham Surrey KT22 9HQ (GB)

(74)	Representative: Waters, Jeffrey
	The General Electric Company, p.l.c. GEC Patent Department Waterhouse Lane Chelmsford, Essex CM1 2QX Chelmsford, Essex CM1 2QX (GB)

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References cited: :

(54)	Induction heating circuits for cooking appliances

(57) In an induction heating circuit for a cooking appliance, a pan heating coil (L2) is powered at values determined by the state of conduction of a gate turn-off thyristor (VT1). To reduce the amplitude of current flow through the thyristor at turn-on, a circuit responsive to the voltage across a capacitor (CR) that resonates the pan coil (L2) is employed. The circuit is coupled to the resonant circuit comprising pan coil (L2) and capacitor (CR) by a saturating transformer (T1) and senses the instant when the voltage across capacitor (CR) reaches a minimum and this information is used to turn-on the thyristor (VT1).

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