| 摘要 |
<p>A dimmer circuit (100) controls the current delivered from an AC power source (106) to an inductive or capacitive or resistive load (107). The dimmer circuit (100) has first and second semiconductor switches (211, 212) anti-serial coupled between the AC power source (106) and the load (107), and a first control circuit (260) that controls the first and second semiconductor switches (211, 212) to operate respectively in their conducting state or non-conducting state. The dimmer circuit (100) further has a DC power supply circuit (102) with a capacitor (123) that draws current from the AC voltage source (106) during at least part of the conducting state of the first and second semiconductor switches (211, 212) and which supplies DC power to at least the first control circuit (260). The dimmer circuit (100) according to the invention has third and fourth semiconductor switches (231, 232) anti-serial coupled between the first and second semiconductor switches (211, 212), and a second control circuit (270) that control s the third and fourth semiconductor switches (231, 232) to operate into their conducting state during dimming operation and into their non-conducting state during charging and dimming operation of the dimmer circuit (100).</p> |
