| 摘要 |
<p>A power control system for gas discharge lamps and other loads includes a main divertor (200) in series or parallel with the load, and a variable divertor (156), which includes a controllably conductive device (158) controlled by a control circuit (100,154), the variable divertor being selectively inserted in series with the load during each half cycle of the output voltage signal. The system obtains an improved load voltage waveform giving superior performance under reduced power output conditions. This system can be applied to a fluorescent lighting circuit having a plurality of conventional ballasts, achieving a dimming ratio of greater than 4 to 1, and can also be applied to other gas discharge lamp circuits, including high intensity discharge lamp circuits, to incandescent lamps, and to motors such as fan motors. It can further be applied to control the power supplied to solid-state switching units, including those having capacitive inputs. The system produces a waveform having no sharp voltage changes, and thus virtually no audible noise emanates from the load. Radiated and conducted EMI are significantly lower than with existing controls. The advantageous waveform is generated while maintaining an efficiency greater than about 95 percent.</p> |
