In the development of electronic machine, the high efficiency of the power supply is important. Not only face the problem of electricity energy in Japan, in the world of electric power companies, power factor correction machine to promote and improve the increasingly important. In this paper, the AC/DC power supply with high power factor correction and standby power is introduced.
First, the power factor and power factor correction circuit (factor correction Power; PFC) to do a simple description. The so-called power factor is the ratio of the effective current to the total current. Power factor of the AC voltage and current phase difference phi, to power factor = cos phi is calculated, the voltage and current not sine wave phase difference is 1. Simply, a simple resistive load has no phase delay due to the voltage and current waveforms, and the power factor is 1.
However, most modern electronic machines use a switched mode power supply, which uses capacitors to smooth the AC voltage. Due to the use of smoothing with a capacitive load, the input AC voltage is only in the state of higher than the smooth capacitance voltage flow, the conduction angle becomes small, the current waveform into a high-frequency component of non sinusoidal current.