PPOWEROWER FFACTORACTOR CCORRECTORORRECTOR S6500 Marketing Team 张飞实战电子官方网站：zhangfeidz? 点击打开 POWER FACTOR CORRECTOR Introduction Introduction Conventional AC/DC Converter, most electronic ballast and SMPS, employ a full wave rectifier bridge with a simple capacitor filter to draw DC power from the mains AC, Fig.1 Fig. 1 Uncorrected power factor circuit This filter capacitor must be large enough to supply the total power during most of each half-cycle while instantaneous line voltage is below the DC output voltage. With this Bulk capacitor filter, the line current waveform is a narrow pulse, this occurs near the line voltage peak and results in a high charge current spike, Fig 2. Fig. 2 Uncorrected power factor input waveform figure 张飞实战电子官方网站：zhangfeidz? 点击打开 POWER FACTOR CORRECTOR Since power is only taken near the line voltage peaks, the resulting spikes of current are extremely non-sinusoidal with a high content of harmonics. This results in a poor power factor condition. Power Factor ratios of 0.5 to 0.7 are common. Power factor correction can be achieved with the use of either a passive or an active input circuit. Passive circuits usually contain a combination of large capacitors, inductors, and rectifiers that operate at the ac line frequency. Active circuits incorporate some form of a high f