Charging device and charging method for charging a battery

A charging device, comprising:

• a charging receiving terminal, configured to receive an alternating current from a mains supply;
• a voltage adjusting circuit, having an input end coupled to the charging receiving terminal and comprising a first rectifier, a switch unit, a transformer and a synthesizing unit, wherein
• the first rectifier is configured to rectify the alternating current from the mains supply and to output a voltage with a first pulsating waveform;
• the switch unit is configured to modulate the voltage with the first pulsating waveform according to a control signal;
• the transformer is configured to output a plurality of voltages with pulsating waveforms according to the modulated voltage with the first pulsating waveform;
• and
• the synthesizing unit is configured to synthesize the plurality of voltages with the pulsating waveforms to output a second alternating current;
• wherein
• an output end of the voltage adjusting circuit is configured to be coupled to a battery such that the second alternating current is applied to the battery directly, and for each cycle of the second alternating current, a peak voltage of a positive half is greater than an absolute value of a valley voltage of a negative half, the transformer comprises a primary winding, a first secondary winding and a second secondary winding, a first end of the primary winding is coupled to a first output end of the first rectifier, a second end of the primary winding is coupled to the switch unit, the first secondary winding and the second secondary winding both are coupled to the synthesizing unit, and the transformer is configured to output a voltage with a second pulsating waveform via the first secondary winding according to the modulated voltage with the first pulsating waveform and to output a voltage with a third pulsating waveform via the second secondary winding according to the modulated voltage with the first pulsating waveform, and the synthesizing unit is configured to synthesize the voltage with the second pulsating waveform and the voltage with the third pulsating waveform to output the second alternating current;
• and
• a central control module, configured to output the control signal to the switch unit so as to adjust at least one of a voltage and a current of the second alternating current outputted by the voltage adjusting circuit, in response to a charging requirement of the battery.