| 摘要 |
<p>A power adaptor 20 comprises an input 22 for connection to a mains supply, a filtering and rectifying circuit 30, and a resonant circuit 34, including a drive circuit (42, fig. 3), that provides an output 24 suitable for driving a load. A controller is adapted to determine the waveform of the current drawn from the input by the drive circuit, and to modify the current waveform that would inherently be drawn from the input by the drive circuit to reduce variation in instantaneous output power over each mains cycle. In particular from a sinusoidal wave to a square wave or inverted sinusoidal wave. The power adaptor may be suitable for driving a solid state light source, such as an LED, or a non-solid state light source, e.g. compact fluorescent lamp.</p> |
