POWER SOURCE PROVIDING APPARATUS, AND CHARGING METHOD AND SYSTEM

A power supply device, includes a rectifier circuit configured to perform rectification on alternating-current power to obtain a first pulsating direct-current voltage, a first-stage conversion circuit connected to the rectifier circuit and configured to perform isolation conversion on the first pulsating direct-current voltage to thereby obtain a second pulsating direct-current voltage; a second-stage conversion circuit connected to the first-stage conversion circuit and configured to convert the second pulsating direct-current voltage into a stable direct-current voltage; and a valley-fill circuit connected to the rectifier circuit and the first-stage conversion circuit individually, wherein the valley-fill circuit is configured to supply, in response to a voltage value of the first pulsating direct-current being less than a first voltage threshold, electrical power to an input of the first-stage conversion circuit to thereby increase a valley voltage of the first pulsating direct-current voltage.