Power factor correction circuit

Abstract

The present invention relates to a power factor correction circuit, that can include: an inductor current detector that generates a sampling voltage signal, and sinusoidal half-wave current and voltage signals based on the sampling voltage signal; a mediate signal generator generating slope voltage and clock signals in response to the sinusoidal half-wave voltage signal, where a frequency of each varies with the sinusoidal half-wave voltage signal; a current modulation circuit receiving the sinusoidal half-wave current signal and a voltage feedback signal representative of a power stage output voltage to generate a regulation signal that is compared against the slope voltage signal to generate a modulation signal; and a logic / driving circuit receiving the modulation and clock signals, and generating a controlling signal that controls a power switch with variable frequency to maintain the inductor current in phase with the sinusoidal half-wave voltage signal and the power stage output voltage constant.

Description

technical field [0001] The invention relates to the field of power supplies, and more specifically, relates to a power factor correction circuit applied in power supplies. Background technique [0002] The AC / DC power supply in the prior art generally includes: EMI (Electromagnetic Interference, electromagnetic interference) filter network, rectifier circuit, power factor correction circuit and power stage circuit, figure 1 It is a working principle block diagram of the AC / DC power supply in the prior art. The alternating current AC is filtered by the EMI filter network 11, and after the electromagnetic interference is eliminated, the voltage output by the EMI filter network 11 is rectified by the full-bridge rectifier circuit 12, and then the voltage output from the full-bridge rectifier circuit 12 is further rectified by the power factor correction circuit 13 power factor correction, and finally input the voltage after power factor correction to the load 14 to drive the l...

AI Technical Summary

Problems solved by technology

In order to realize the variability of switching frequency, frequency synthesis technology is usually used, such as using a separate dedicated chip for generating variable frequency, but the method of using a separate dedicated chip for generating variable frequency will also greatly increase the cost of system implementation, and will not Conducive to miniaturization and integration of circuits

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