US Patent No. 10,462,859

CLOCKED FLYBACK CONVERTER CIRCUIT


Patent No. 10,462,859
Issue Date October 29, 2019
Title Clocked Flyback Converter Circuit
Inventorship Andre Mitterbacher, Dornbirn (AT)
Assignee

Claim of US Patent No. 10,462,859

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; and wherein the transformer (5) has a primary-side auxiliary winding (15), to which the control unit (14) is coupled in order to record a voltage curve over the auxiliary winding (15), and the control unit (14) switches the switch back on when operating in the discontinuous mode at a point in time at which the voltage is at a zero crossing after a local minimum in the voltage curve; and further wherein a dimming signal (D) can be sent to the control unit (14), and the control unit is configured to modify the switch-off threshold (Is) in accordance with the dimming signal in the limit mode, and is configured to modify the point in time of switching the switch back on in accordance with the dimming signal (D) in the discontinuous mode when the minimum value (Imin) serves as the fixed switch off threshold.