Power converter and method of operating the same

A power converter, configured to receive an input voltage, and provide an output voltage to supply power to a load, the power converter comprising:

• a power factor correction circuit, configured to receive the input voltage, and comprising at least one power switch, and
• a controller, coupled to the at least one power switch, and configured to control the switching of the at least one power switch, and control the power factor correction circuit converting the input voltage into the output voltage, and control an input current of the power factor correction circuit to follow the input voltage,
• wherein the controller acquires a switching frequency and a frequency range based on an instantaneous value of the input voltage and an effective value of the input current, wherein the frequency range comprises an upper limit frequency and a lower limit frequency;
• when the controller determines that the effective value is greater than a medium load threshold, an operation mode of the power factor correction circuit is switched from a critical conduction mode to a continuous conduction mode, and to limit the switching frequency to the lower limit frequency based on the switching frequency being less than the lower limit frequency;
• or the operation mode is switched from a triangular current mode to the continuous conduction mode, and to limit the switching frequency to the lower limit frequency,
• wherein when the controller determines that the effective value is greater than the medium load threshold, the controller adjusts the lower limit frequency between a first lower limit frequency and a second lower limit frequency based on the increasing or decreasing of the effective value.