CONVERTER FOR OPERATING AN LED LOAD, AND LIGHTING SYSTEM
A converter (1) for operating an LED load is provided. The converter (1) comprises an actively switched power factor correction, PFC, circuitry (104-112), having a control circuitry (2-4) for controlling a switch (105) of the PFC circuitry (104-112). The control circuitry (2-4) is configured to cont...
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Format: | Patent |
Sprache: | eng ; fre ; ger |
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Zusammenfassung: | A converter (1) for operating an LED load is provided. The converter (1) comprises an actively switched power factor correction, PFC, circuitry (104-112), having a control circuitry (2-4) for controlling a switch (105) of the PFC circuitry (104-112). The control circuitry (2-4) is configured to control a switch-on timing of the switch (105) such that an output voltage (113, Vbus) of the PFC circuitry (104-112) is feedback-controlled in accordance with a nominal value (201). In a discontinuous conduction mode, DCM, the control circuitry (2-4) is configured to control an actual value (204, Toff_act) of the switch-on timing of the switch (105) in one or more switching cycles to be a time of a valley of a voltage across the switch (105) succeeding a nominal value (302, Toff_nom) of the switch-on timing of a control algorithm implemented by the control circuitry (2-4). The control circuitry (2-4) is further configured to control the actual value (204, Toff_act) of the switch-on timing of the switch (105) in one or more subsequent switching cycles being subsequent to the one or more switching cycles to be a time of a valley of the voltage across the switch (105) preceding the nominal value (302, Toff_nom) of the switch-on timing. This reconciles valley switching and avoidance of visible light flicker. |
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