POWER FACTOR COMPENSATION CIRCUIT FOR BOOSTER TYPE CONVERTER HAVING OUTPUT VOLTAGE COMPENSATION FUNCTION

摘要

The disclosed power factor correction circuit compensates for the variation of the output DC voltage to reduce current distortion and obtain high power factor, and the configuration of the circuit is simplified by maintaining the in-phase and increasing the level of the input current according to the input AC voltage without configuring the feedforward. Let's do it.;According to an exemplary embodiment of the present invention, a boost converter accumulates energy in a coil and superimposes an input DC voltage on energy stored in the coil according to on and off states of the switching transistor, and a current sensing unit has a small resistance value in series with the switching transistor. The detection resistor is connected to detect the current flowing when the switching transistor is turned on, and then amplifies and outputs the current.The comparison reference voltage signal and the output DC voltage at which the level of the output detector varies according to the change of the output DC voltage output by the boost converter Compensation voltage signal is generated to compensate for the variation of the signal, the first signal synthesizer synthesizes the comparison reference voltage signal generated by the output detector and the voltage signal detected by the current detector to generate a comparison signal, the compensation generated by the output detector The second signal synthesizing unit combines the voltage signal and the reverse sawtooth wave signal to determine the output DC voltage. A variation compensated reverse sawtooth signal is generated, a comparator compares the comparison signal of the first signal synthesizer with the compensated reverse sawtooth signal of the second signal combiner to generate an off control signal of the switching transistor, and a rising edge of the reverse sawtooth signal The driving unit turns on the switching transistor in response to a clock signal synchronized with the control signal, and turns off the switching transistor according to the off control signal of the comparator.