A charging system for an electric vehicle, said charging system comprising: a power battery; a charge-discharge socket; a charging connection device comprising a first plug configured to be connected with an external power supply device and a second plug configured to be connected with the charge-discharge socket; and an energy control device, comprising: a bidirectional DC-AC module having a first DC terminal connected with a first terminal of the power battery and a second DC terminal connected with a second terminal of the power battery; a charge-discharge control module having a first terminal connected with an AC terminal of the bidirectional DC-AC module and a second terminal connected with the charge-discharge socket; and a control module connected with a third terminal of the charge-discharge control module and a control terminal of the bidirectional DC-AC module and configured to control the charge-discharge control module according to a current working mode of the electric vehicle; wherein the energy control device is configured to transmit a modulated signal to and receive a modulated signal from the external power supply device via the charging connection device and to communicate with the external power supply device via the modulated signal, and the control module is configured to control the bidirectional DC-AC module and the charge-discharge control module to charge the power battery by the external power supply device, and characterised in that the energy control device further comprises: a first common-mode capacitor and a second common-mode capacitor connected in series and connected between the first terminal and the second terminal of the power battery, in which a node between the first common-mode capacitor and the second common-mode capacitor is grounded, and in that said bidirectional DC-AC module is a three-level bidirectional DC-AC module, and said modulated signal is a PWM signal. a power battery; a charge-discharge socket; a charging connection device comprising a first plug configured to be connected with an external power supply device and a second plug configured to be connected with the charge-discharge socket; and an energy control device, comprising: a bidirectional DC-AC module having a first DC terminal connected with a first terminal of the power battery and a second DC terminal connected with a second terminal of the power battery; a charge-discharge control module having a first terminal connected with an AC terminal of the bidirectional DC-AC module and a second terminal connected with the charge-discharge socket; and a control module connected with a third terminal of the charge-discharge control module and a control terminal of the bidirectional DC-AC module and configured to control the charge-discharge control module according to a current working mode of the electric vehicle; a bidirectional DC-AC module having a first DC terminal connected with a first terminal of the power battery and a second DC terminal connected with a second terminal of the power battery; a charge-discharge control module having a first terminal connected with an AC terminal of the bidirectional DC-AC module and a second terminal connected with the charge-discharge socket; and a control module connected with a third terminal of the charge-discharge control module and a control terminal of the bidirectional DC-AC module and configured to control the charge-discharge control module according to a current working mode of the electric vehicle; wherein the energy control device is configured to transmit a modulated signal to and receive a modulated signal from the external power supply device via the charging connection device and to communicate with the external power supply device via the modulated signal, and the control module is configured to control the bidirectional DC-AC module and the charge-discharge control module to charge the power battery by the external power supply device, and characterised in that the energy control device further comprises: a first common-mode capacitor and a second common-mode capacitor connected in series and connected between the first terminal and the second terminal of the power battery, in which a node between the first common-mode capacitor and the second common-mode capacitor is grounded, and in that said bidirectional DC-AC module is a three-level bidirectional DC-AC module, and said modulated signal is a PWM signal.