Induction heating cooker operated at a constant oscillation frequency
First Claim
Patent Images
1. An induction heating cooker comprising:
- a heating coil,a first resonance capacitor which is coupled at one end thereof to one end of said heating coil and connected at the other end thereof to a direct current source,a diode coupled in parallel with said first resonance capacitor,a first switching device of a reverse current blocking type coupled at one end thereof to the other end of said heating coil,a second switching device of a reverse current conducting type coupled at one end thereof to said one end of said first switching device and to the other end of said heating coil and coupled at the other end thereof to said other end of said first resonance capacitor,a second resonance capacitor coupled across said second switching device,a control circuit comprising driving means for alternately conducting said first switching device and said second switching device at a constant frequency and for varying a DUTY FACTOR defined as a ratio of a conductive period of one of said two switching devices to a period of said signal of said constant frequency, andan oppositely poled diode coupled across the collector-emitter portion of a switching element provided in said first switching device.
1 Assignment
0 Petitions
Accused Products
Abstract
In a switching device of an induction heating cooker, an oppositely poled diode for conducting a reverse current is coupled across the collector-emitter portion of a switching element provided in the first switching device, and turn-ON operation of the switching devices does not OCCUR in normal operation of the DUTY FACTOR T2 /T1 ≈0.5.
-
Citations
13 Claims
-
1. An induction heating cooker comprising:
-
a heating coil, a first resonance capacitor which is coupled at one end thereof to one end of said heating coil and connected at the other end thereof to a direct current source, a diode coupled in parallel with said first resonance capacitor, a first switching device of a reverse current blocking type coupled at one end thereof to the other end of said heating coil, a second switching device of a reverse current conducting type coupled at one end thereof to said one end of said first switching device and to the other end of said heating coil and coupled at the other end thereof to said other end of said first resonance capacitor, a second resonance capacitor coupled across said second switching device, a control circuit comprising driving means for alternately conducting said first switching device and said second switching device at a constant frequency and for varying a DUTY FACTOR defined as a ratio of a conductive period of one of said two switching devices to a period of said signal of said constant frequency, and an oppositely poled diode coupled across the collector-emitter portion of a switching element provided in said first switching device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. An induction heating cooker comprising:
-
a first switching device and a second switching device connected in series across both ends of a direct current source, a heating coil connected at one end to a junction of one end of said first switching device and one end of said second switching device, a first resonance capacitor connected across the other end of said heating coil and the other end of said second switching device, a diode connected across both ends of said first resonance capacitor so that a current passes through a loop of said heating coil, said second switching device and said diode in the direction from said heating coil to said diode through said second switching device, and a second resonance capacitor connected in parallel to said second switching device, wherein a first dead time defined as a time period from turn-OFF of said first switching device to turn-ON of second switching device is set to a different value from a second dead time defined as a time period from turn-OFF of second switching device to turn-ON of said first switching device.
-
-
12. An induction heating cooker comprising:
-
a first switching device and a second switching device connected in series across both ends of a direct current source, a heating coil connected at one end to a junction of one end of said first switching device and one end of said second switching device, a first resonance capacitor connected across the other end of said heating coil and the other end of said second switching device, a diode connected across both ends of said first resonance capacitor so that a current passes through a loop of said heating coil, said second switching device and said diode in the direction from said heating coil to said diode through said second switching device, a second resonance capacitor connected in parallel to said second switching device, and second voltage detection means for detecting a voltage of said second resonance capacitor, wherein in the case that the output of said second voltage detection means is a predetermined value and below, operation or suspension of said operation of said switching devices is alternately repeated by said control circuit and an input is controlled by changing a ratio of a time length of said operation to a time length of said suspension.
-
-
13. An induction heating cooker comprising:
-
a first switching device and a second switching device connected in series across both ends of a direct current source, a heating coil connected at one end to a junction of one end of said first switching device and one end of said second switching device, a first resonance capacitor connected across the other end of said heating coil and the other end of said second switching device, a diode connected across both ends of said first resonance capacitor so that a current passes through a loop of said heating coil, said second switching device and said diode in the direction from said heating coil to said diode through said second switching device, a second resonance capacitor connected in parallel to said second switching device, and input setting means for setting an input by a user, wherein, in the case that the input set by said user is a predetermined value and below, operation or suspension of said operation of said switching devices is alternately repeated by said control circuit and said input is controlled by changing a ratio of a time length of said operation to a time length of said suspension.
-
Specification