| 摘要 |
<p>A method of sensing the rms value of a phase chopped sinusoidal electrical waveform comprising the steps of combining an input signal (8) representative of the waveform with an auxiliary signal (17) in a combining circuit (14, 16) which produces a combining circuit output (19) equal to whichever is the greater of the auxiliary signal and the modulus of the input signal, and averaging the combining circuit output over at least one half cycle of the wavweform. The resulting output signal level (21) is representative of the sensed rms value. By making the auxiliary signal equal to the product of a predetermined factor multiplied by a desired value of the output signal level, a feedback signal (10) is produced to allow control of the rms voltage delivered to a load (1) such as a lighting circuit.</p> |
