| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve more accurate detection of voltage from a commercial AC source than ever before even if the voltage from the commercial AC source is distorted. <P>SOLUTION: A zero-cross and voltage detection circuit 120 generates a pulse wave with a duty ratio corresponding to a peak value of output voltage from a diode bridge 2 or DC voltage from a primary electric field capacitor 3. A CPU 29 receives the pulse wave, obtains the duty ratio of the pulse wave and estimates the voltage from a commercial AC source 1 from the duty ratio. The peak value of the output voltage of the diode bridge 2 or the DC voltage from the primary electric field capacitor 3 is hardly affected by distortion. Therefore, the invention enables more accurate detection of the voltage from the commercial AC source 1 than ever before. <P>COPYRIGHT: (C)2013,JPO&INPIT |
