CHARGING METHOD, CHARGING APPARATUS, AND CHARGING SYSTEM FOR TRACTION BATTERY

1 . A charging method for a traction battery, performed by a charging apparatus, wherein the charging apparatus comprises N energy storage units connected in parallel, each energy storage unit comprises an energy storage battery and a first DC/DC converter connected to the energy storage battery, and each charging period of the charging apparatus comprises a stage in which the traction battery is charged and a stage in which the traction battery discharges to the N energy storage units, N being a positive integer greater than 1;

wherein the charging method comprises:

obtaining a first parameter of each energy storage unit in the discharge stage;

determining, based on the first parameter, a first current output by the first DC/DC converter in each energy storage unit, wherein the first current output by the first DC/DC converter in each energy storage unit is inversely proportional to the first parameter of the energy storage unit; and

sending a first control signal to the first DC/DC converter in each energy storage unit, wherein the first control signal is used to control the first DC/DC converter to output the first current, so as to cause the first DC/DC converter in each energy storage unit to receive, at the first current, electrical energy released by the traction battery.

2 . The charging method according to claim 1 , wherein the method further comprises:

obtaining the first parameter of each energy storage unit in the charge stage;

determining, based on the first parameter, a second current output by the first DC/DC converter in each energy storage unit, wherein the second current output by the first DC/DC converter in each energy storage unit is proportional to the first parameter of the energy storage unit; and

sending a second control signal to the first DC/DC converter in each energy storage unit, wherein the second control signal is used to control the first DC/DC converter to output the second current, so as to cause the first DC/DC converter in each energy storage unit to charge the traction battery at the second current.

3 . The charging method according to claim 1 , wherein the first parameter of each energy storage unit comprises at least one of the following parameters:

current state of charge (SOC) of the energy storage battery in each energy storage unit;

current voltage of the energy storage battery in each energy storage unit; and

current voltage of each energy storage unit.

4 . The charging method according to claim 1 , wherein the charging apparatus further comprises a separating unit, the separating unit is connected between the N energy storage units and the traction battery, and the separating unit comprises M second DC/DC converters and a switch module connected between the M second DC/DC converters, M being a positive integer greater than or equal to 2; and

wherein the charging method further comprises:

controlling the switch module to make the M second DC/DC converters connected in series, so that voltage output by the separating unit to the traction battery is M times voltage output by the N energy storage units; or

controlling the switch module to make the M second DC/DC converters connected in parallel, so that current output by the separating unit to the traction battery is M times current output by the N energy storage units.

5 . The charging method according to claim 1 , wherein the charging apparatus further comprises an AC/DC converter, the AC/DC converter is connected between the traction battery and an alternating current power supply, so as to cause the alternating current power supply to charge the traction battery via the AC/DC converter.

6 . A charging apparatus for a traction battery, comprising:

N energy storage units connected in parallel, wherein each energy storage unit comprises an energy storage battery and a first DC/DC converter connected to the energy storage battery, and each charging period of the charging apparatus comprises a stage in which the traction battery is charged and a stage in which the traction battery discharges to the N energy storage units, N being a positive integer greater than 1; and

a control module,

wherein the control module is configured to:

obtain a first parameter of each energy storage unit in the discharge stage;

determine, based on the first parameter, a first current output by the first DC/DC converter in each energy storage unit, wherein the first current output by the first DC/DC converter in each energy storage unit is inversely proportional to the first parameter of the energy storage unit; and

send a first control signal to the first DC/DC converter in each energy storage unit, wherein the first control signal is used to control the first DC/DC converter to output the first current, so as to cause the first DC/DC converter in each energy storage unit to receive, at the first current, electrical energy released by the traction battery.

7 . The charging apparatus according to claim 6 , wherein the control module is further configured to:

obtain the first parameter of each energy storage unit in the charge stage;

determine, based on the first parameter, a second current output by the first DC/DC converter in each energy storage unit, wherein the second current output by the first DC/DC converter in each energy storage unit is proportional to the first parameter of the energy storage unit; and

send a second control signal to the first DC/DC converter in each energy storage unit, wherein the second control signal is used to control the first DC/DC converter to output the second current, so as to cause the first DC/DC converter in each energy storage unit to charge the traction battery at the second current.

8 . The charging apparatus according to claim 6 , wherein the first parameter of each energy storage unit comprises at least one of the following parameters:

current state of charge (SOC) of the energy storage battery in each energy storage unit;

current voltage of the energy storage battery in each energy storage unit; and

current voltage of each energy storage unit.

9 . The charging apparatus according to claim 6 , wherein the charging apparatus further comprises a separating unit, the separating unit is connected between the N energy storage units and the traction battery, and the separating unit comprises M second DC/DC converters and a switch module connected between the M second DC/DC converters, M being a positive integer greater than or equal to 2; and

wherein the control module is further configured to:

control the switch module to make the M second DC/DC converters connected in series, so that voltage output by the separating unit to the traction battery is M times voltage output by the N energy storage units; or

control the switch module to make the M second DC/DC converters connected in parallel so that current output by the separating unit to the traction battery is M times current output by the N energy storage units.

10 . The charging apparatus according to claim 6 , wherein the charging apparatus further comprises an AC/DC converter, the AC/DC converter is connected between the traction battery and an alternating current power supply, so as to cause the alternating current power supply to charge the traction battery via the AC/DC converter.

11 . An energy management system (EMS), comprising a processor, wherein the processor is configured to perform the charging method according to claim 1 .

12 . A charging system, comprising:

a traction battery; and

the charging apparatus according to claim 6 , wherein the charging apparatus is configured to charge the traction battery, and each charging period comprises a stage in which the traction battery is charged and a stage in which the traction battery discharges.