POWER SUPPLY DEVICE, CIRCUIT CONTROL METHOD, AND POWER SUPPLY SYSTEM

A power supply device includes: an input rectifier circuit configured to convert a received alternating-current power into a first pulsating direct-current voltage; a first-stage conversion circuit connected with the input rectifier circuit and configured to convert the first pulsating direct-current voltage into a second pulsating direct-current voltage; a valley-fill circuit connected with the first-stage conversion circuit and configured to supply, in response to a voltage value of the second pulsating direct-current voltage being lower than a voltage threshold, electrical power to thereby enable the voltage value of the second pulsating direct-current voltage to be greater than or equal to the voltage threshold; and a second-stage conversion circuit connected with the first-stage conversion circuit and configured to convert the second pulsating direct-current voltage into a constant direct-current voltage and output the constant direct-current voltage.