TWI456371B - Power factor corrector control circuit - Google Patents

Claims (10)

A control circuit for a power factor corrector, the AC input voltage is rectified and converted into a rectified voltage, and the control circuit outputs a switching signal to control a power switch, which comprises: a partial voltage filter The circuit generates a RMS voltage signal and an input current signal according to the voltage and voltage of the rectified voltage, wherein the waveform of the input current signal is the same as the waveform of the rectified voltage, and the current level is improved; The circuit generates a control signal according to the input current signal, the rms voltage signal and an error signal, wherein the error signal is generated by an output of the power factor corrector; and a switching circuit coupled to the The gain modulation circuit outputs the switching signal according to the control signal and a sawtooth wave signal; wherein the input current signal having the DC level is used to increase one of the switching signals at a zero point of an input inductor current cycle. The control circuit of claim 1, further comprising a voltage error amplifier coupled between the output of the power factor corrector and the gain modulation circuit, wherein the voltage error amplifier is based on the output A voltage feedback signal generated and a predetermined voltage are amplified by the error, and the error signal is output and transmitted to the gain modulation circuit. The control circuit of claim 1, wherein the switching circuit comprises: a current sensing resistor coupled to the power switch for sensing the input inductor current to generate a switching current signal; an amplifier, And summing the control signal and the switching current signal, and outputting an amplification signal through error amplification; and a comparator coupled to the amplifier, and outputting the switching signal according to the amplified signal and the sawtooth wave signal For controlling the switching of the power switch and the adjustment of the duty cycle. The control circuit as described in claim 1 further includes a detecting resistor coupled to One of the voltage dividing filter circuits divides the node to generate the input current signal. A control circuit for a power factor corrector, the AC input voltage is rectified and converted into a rectified voltage, and the control circuit outputs a switching signal to control a power switch, which comprises: a quasi-boost The circuit generates an input current signal according to the rectified voltage and a certain current signal, wherein the waveform of the input current signal is the same as the waveform of the rectified voltage, and the DC current level is raised; and a gain modulation circuit according to the input current The signal, the rms voltage signal and the error signal generate a control signal, wherein the rms voltage signal is generated by dividing and filtering the rectified voltage, and the error signal is outputted by one of the power factor correctors And generating, by the switching circuit, the gain modulation circuit, outputting the switching signal according to the control signal and a sawtooth wave signal; wherein the input current signal having the DC level is used for an input inductor The duty cycle of the switching signal is increased at the zero point of the current. The control circuit of claim 5, wherein the level boosting circuit comprises: a voltage/current converting circuit, converting the rectified voltage into a corresponding first current signal; and a current mirror, the first The current signal is converted into a corresponding second current signal; and a current source is provided to provide the constant current signal to add the second current signal to generate the input current signal, wherein the size of the DC level is determined by the predetermined current signal The current signal is determined. The control circuit of claim 5, further comprising a voltage error amplifier coupled between the output of the power factor corrector and the gain modulation circuit, wherein the voltage error amplifier is based on the output A voltage feedback signal generated and a predetermined voltage are amplified by the error, and the error signal is output and transmitted to the gain modulation circuit. The control circuit of claim 5, wherein the switching circuit comprises: a current sensing resistor coupled to the power switch for sensing the input inductor current Generating a switching current signal; an amplifier summing the control signal and the switching current signal, and outputting an amplification signal through error amplification; and a comparator coupled to the amplifier, according to the amplification signal and the sawtooth The wave signal outputs the switching signal after comparison to control the switching of the power switch and the adjustment of the duty cycle. The control circuit according to claim 5, further comprising a voltage dividing filter circuit, wherein the rms voltage signal is generated after being divided and filtered according to the rectified voltage. The control circuit of claim 5, further comprising a voltage dividing circuit that divides the rectified voltage for the level boosting circuit to generate the input current signal.