CLOCKED FLYBACK CONVERTER CIRCUIT
First Claim
1. A clocked flyback converter circuit for operating one or more lighting means (11), comprising:
- a controllable switch (7);
a transformer (5) having a primary winding (4), which is coupled to the controllable switch (7), and a secondary winding (6), to which lighting means (11) can be coupled;
a control device (14) for activating the switch (7); and
means (8) for direct or indirect recording of the current through the switch (7) in the switched-on state, and for supplying a signal reflecting this current to the control unit (14);
wherein the control unit (14) is configured to switch the switch (7) off when the signal reflecting the current has reached a variable switch-off threshold (Is), to modify the switch-off threshold (Is) for modifying the power transmitted by the flyback converter circuit (3) but not below a minimum value (Imin), and to switch from operation in the limit mode to operation in a discontinuous mode in order to obtain a further reduction of the power transmitted by the flyback converter circuit (3) where the minimum value (Imin) serves as a fixed switch-off threshold.
1 Assignment
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Accused Products
Abstract
The invention relates to a clocked flyback converter circuit for directly operating lighting means comprising: a transformer (5), which has a primary winding (4), which is coupled to a controllable switch (7), and a secondary winding (6), to which the lighting means (11) can be coupled; a control unit (14) for controlling the switch (7); and means (8) for directly or indirectly sensing the current through the switch (7) in the switched-on state and for feeding a signal and reflecting said current to the control unit (14). The control unit (14) is designed to switch off the switch (7) if the signal reflecting the current has reached a variable switch-off threshold (Is), to change the switch-off threshold (Is) in order to change the power transmitted by the flyback converter circuit (3), and to reduce the switch-off threshold (Is) for the current signal only down to a minimum value and to switch from operation in the limit mode to discontinuous operation in order to achieve a further reduction in the power transmitted by the flyback converter circuit (3) while the switch-off threshold (Is) is fixed.
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Citations
14 Claims
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1. A clocked flyback converter circuit for operating one or more lighting means (11), comprising:
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a controllable switch (7); a transformer (5) having a primary winding (4), which is coupled to the controllable switch (7), and a secondary winding (6), to which lighting means (11) can be coupled; a control device (14) for activating the switch (7); and means (8) for direct or indirect recording of the current through the switch (7) in the switched-on state, and for supplying a signal reflecting this current to the control unit (14); wherein the control unit (14) is configured to switch the switch (7) off when the signal reflecting the current has reached a variable switch-off threshold (Is), to modify the switch-off threshold (Is) for modifying the power transmitted by the flyback converter circuit (3) but not below a minimum value (Imin), and to switch from operation in the limit mode to operation in a discontinuous mode in order to obtain a further reduction of the power transmitted by the flyback converter circuit (3) where the minimum value (Imin) serves as a fixed switch-off threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling a clocked flyback converter circuit (3) that has a transformer (5), in which a primary winding (4) of the transformer is coupled to a controllable switch (3) and a secondary winding (2) of the transformer (5) is coupled to one or more lighting means (11), comprising the steps:
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activating the switch (7); and recording the current flowing through the switch (7), and generating a signal reflecting this current; wherein in a limit mode of operation the switch (7) is switched off when the signal indicates that the current has reached a variable switch-off threshold (Is), and the switch-off threshold (Is) is modified in the limit mode of operation in order to modify the power that is to be transmitted by the flyback converter circuit (3), wherein the switch-off threshold (Is) is not reduced below a minimum value (Imin); and further wherein in a discontinuous mode of operation the minimum value (Imin) serves as a fixed switch-off threshold (Is) and the switch (7) is switched off at the fixed switch threshold and remains off during a cycle for a period of time after the current flowing through the switch reaches zero before the switch is is switched on for the next cycle, in order to obtain a further reduction of the power transmitted by flyback converter circuit (3). - View Dependent Claims (11, 12, 13, 14)
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Specification