| 摘要 |
An AC-DC converting apparatus includes a main circuit having a fully-wave rectifier for rectifying an alternating current from an AC power supply, a reactor connected to the rectifier, and a switching element for alternately causing the reactor to store and to release electrical energy. The converting apparatus further includes a current detection circuit for generating a current detection signal indicative of the current flowing into the apparatus, and a voltage waveform detecting circuit having a 4-diode bridge for rectifying the input current of the power supply, and a photocoupler for generating an input voltage waveform signal indicative of the rectified waveform of the input voltage. Positive reference waveform and negative reference waveform smaller in amplitude than the positive reference waveform are generated from the input voltage waveform signal. A current detection signal is compared to the positive and negative reference waveforms to close the switching element when the current detection signal falls under the negative reference waveform and to open the switching element when the current detection signal exceeds the positive reference signal. This construction may reduce the size of the apparatus and mya avoid distortion of the detected waveform of the input voltage. |
