Power factor correction converter control offset

摘要

A power supply arrangement includes a PFC converter, an LLC converter, a control unit and an offset unit. The control unit generates a control signal to control a duty cycle of a PWM (Pulse Width Modulation) signal to control the PFC converter. The control unit includes a PWM converter that generates the PWM signal to which a switching circuit is responsive to switch a current representing an input current of the PFC converter. An amplifier receives a current sense signal and provides the current representing the input current of the PFC converter. An offset unit generates a variable offset signal to offset the control signal or a signal used by the control unit to generate the control signal. The variable offset signal is an offset current coupled to offset the current sense signal received at the input of the amplifier.