An on-board charging apparatus, comprising an alternating current to direct current, AC/DC conversion circuit, a power factor correction, PFC circuit, and a direct current to direct current, DC/DC conversion circuit, wherein the DC/DC conversion circuit comprises a second H-bridge rectifier circuit, an isolation transformer, and a third H-bridge rectifier circuit, a primary-side winding of the isolation transformer is coupled to the second H-bridge rectifier circuit, and a secondary-side winding of the isolation transformer is coupled to the third H-bridge rectifier circuit; an alternating current terminal of the AC/DC conversion circuit is connected to an alternating current terminal of the PFC circuit, a direct current terminal of the AC/DC conversion circuit is connected to a first direct current terminal of the second H-bridge rectifier circuit of the DC/DC conversion circuit, and a direct current terminal of the PFC circuit is connected to a second direct current terminal of the second H-bridge rectifier circuit of the DC/DC conversion circuit; the AC/DC conversion circuit is configured to: receive a first alternating current voltage at the alternating current terminal of the AC/DC conversion circuit, and convert a first component of the first alternating current voltage into a first direct current voltage; the PFC circuit is configured to convert a second component of the first alternating current voltage into a second direct current voltage; and the DC/DC conversion circuit is configured to: convert the first direct current voltage and the second direct current voltage into a third direct current voltage, and output the third direct current voltage to a to-be-charged device, wherin the second H-bridge rectifier circuit is configured to adjust the first direct current voltage and the second direct current voltage; and the third H-bridge rectifier circuit is configured to: rectify the adjusted first direct current voltage and the adjusted second direct current voltage, and output the third direct current voltage to the to-be-charged device. the DC/DC conversion circuit comprises a second H-bridge rectifier circuit, an isolation transformer, and a third H-bridge rectifier circuit, a primary-side winding of the isolation transformer is coupled to the second H-bridge rectifier circuit, and a secondary-side winding of the isolation transformer is coupled to the third H-bridge rectifier circuit; an alternating current terminal of the AC/DC conversion circuit is connected to an alternating current terminal of the PFC circuit, a direct current terminal of the AC/DC conversion circuit is connected to a first direct current terminal of the second H-bridge rectifier circuit of the DC/DC conversion circuit, and a direct current terminal of the PFC circuit is connected to a second direct current terminal of the second H-bridge rectifier circuit of the DC/DC conversion circuit; the AC/DC conversion circuit is configured to: receive a first alternating current voltage at the alternating current terminal of the AC/DC conversion circuit, and convert a first component of the first alternating current voltage into a first direct current voltage; the PFC circuit is configured to convert a second component of the first alternating current voltage into a second direct current voltage; and the DC/DC conversion circuit is configured to: convert the first direct current voltage and the second direct current voltage into a third direct current voltage, and output the third direct current voltage to a to-be-charged device, wherin the second H-bridge rectifier circuit is configured to adjust the first direct current voltage and the second direct current voltage; and the third H-bridge rectifier circuit is configured to: rectify the adjusted first direct current voltage and the adjusted second direct current voltage, and output the third direct current voltage to the to-be-charged device. the second H-bridge rectifier circuit is configured to adjust the first direct current voltage and the second direct current voltage; and the third H-bridge rectifier circuit is configured to: rectify the adjusted first direct current voltage and the adjusted second direct current voltage, and output the third direct current voltage to the to-be-charged device.