Input power factor of high frequency switching power supply

Figure 1 shows the spectrum analysis experimental results of the input current of the high power factor rectifier circuit. At this time, the input current is close to sinusoidal and in phase with the input voltage. At this time, the THD is 8.18%, the mains input power factor PF = 0.992, and the current shunt of each harmonic current is greatly reduced.

Figure 1 High power factor rectifier circuit input power waveform and input current harmonic spectrum

As shown in Figure 1, there are significant differences in the input current harmonics and PF of the rectifier circuit before and after correction, as shown in Table 1.

Table 1 Input current harmonics and PF of the rectifier-capacitor filter circuit before and after PF correction

Figure 2 shows different input current waveforms and corresponding input power factors of the rectifier circuit when a sinusoidal voltage is input.

Figure 2 Different input current waveforms and power factors when the input is a sinusoidal voltage