| 摘要 |
Apparatuses (1, 2) for driving loads (3) via converters (4) comprise first circuits (1) for interfacing phase-cut dimmers (5) and the converters (4). Firing angles of the phase-cut dimmers (5) correspond with first moments in time during periods of voltage signals presented to the phase-cut dimmers (5). The converters (4) draw first current signals from second until third moments in time during the periods. Second circuits (2) control the converters (4) to draw second current signals from fourth until fifth moments in time during the periods, to improve an energy efficiency. The first current signals may be delivered by supplies (6). The second current signals may be delivered by output capacitors (32, 34, 35) of the first circuits (1). The third moments in time may be adaptable. One or more of the first and second and third moments in time may be situated before a zero-crossing of the voltage signal and one or more of the fourth and fifth moments in time may be situated after the zero-crossing. The first circuit (1) comprises a rectifier (11-14) with first and second inputs arranged to be coupled to first and second outputs of the phase-cut dimmer (5) and a filter (31-35) coupled to the rectifier (11-14), the filter (31-35) comprising the one or more output capacitors (32, 34, 35). The first circuit further comprises: a first diode (21) with a first electrode coupled to a first output of the rectifier (11-14) and with a second electrode coupled to the filter (31-35), and a bleeder (41-47) with a main current path (41-43) coupled to the first electrode of the first diode (21) and to the second output of the rectifier (11-14) and with a bias current path (44-47) coupled to the second electrode of the first diode (21) and to the second output of the rectifier (11-14). By withdrawing a bleeder current using the bleeder (41-47), the time-interval during which a current is withdrawn from the phase-cut dimmer (5) may be extended. |
