Method for charging battery, charging and discharging device

1. A charging and discharging device, comprising a first direct current/direct current (DC/DC) converter, a unidirectional alternating current/direct current (AC/DC) converter and a control unit, the first DC/DC converter being a unidirectional DC/DC converter, and the control unit being configured to:

receive a first charging current sent by a battery management system (BMS) of a battery, and control the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through an alternative current (AC) power source based on the first charging current;

receive a first discharging current sent by the BMS, and control the battery to release power based on the first discharging current, wherein the first discharging current is a discharging current sent by the BMS when a first cumulative charge amount of the battery is greater than or equal to a first cumulative charge amount threshold and a voltage of a battery cell of the battery does not exceed a full charge voltage of the battery cell; and

receive a second charging current sent by the BMS, and control the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current, wherein the second charging current is a charging current sent by the BMS when a first cumulative discharge amount of the battery is greater than or equal to a first cumulative discharge amount threshold.

2. The charging and discharging device according to claim 1 , wherein the control unit is further configured to:

receive a second discharging current sent by the BMS, and control the battery to release power based on the second discharging current, wherein the second discharging current is a discharging current sent by the BMS when a second cumulative charge amount of the battery is greater than or equal to a second cumulative charge amount threshold and the voltage of the battery cell of the battery does not exceed the full charge voltage of the battery cell.

3. The charging and discharging device according to claim 1 , wherein the control unit is further configured to:

receive a charge stop command sent by the BMS; and

control, based on the charge stop command, the unidirectional AC/DC converter and the first DC/DC converter to cause the AC power source to stop charging the battery, wherein the charge stop command is a command sent by the BMS when the voltage of the battery cell of the battery exceeds the full charge voltage.

4. The charging and discharging device according to claim 1 , wherein the charging and discharging device further comprises a second DC/DC converter; and

the control unit is specifically configured to:

control, based on the first discharging current, the second DC/DC converter to release the power of the battery into an energy storage unit.

5. The charging and discharging device according to claim 4 , wherein the second DC/DC converter is a bidirectional DC/DC converter, and the control unit is further configured to:

control the second DC/DC converter to charge the battery through the energy storage unit while controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the first charging current; and/or

control the second DC/DC converter to charge the battery through the energy storage unit while controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current.

6. The charging and discharging device according to claim 5 , wherein a first charging power of the energy storage unit to charge the battery is determined according to a discharge capability of the energy storage unit, and a second charging power of the AC power source to charge the battery is a difference between a charging demand power of the battery and the first charging power.

7. The charging and discharging device according to claim 5 , wherein the control unit is specifically configured to:

acquire a battery state of charge (SOC) of the energy storage unit;

under a condition that the SOC is greater than a SOC threshold, control the second DC/DC converter to charge the battery through the energy storage unit, and control the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the first charging current; and/or

under a condition that the SOC is greater than a SOC threshold, control the second DC/DC converter to charge the battery through the energy storage unit, and control the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current.

8. The charging and discharging device according to claim 1 , wherein a charging rate of the first charging current and/or the second charging current ranges from 2C to 10C.

9. The charging and discharging device according to claim 1 , wherein a discharging rate of the first discharging current ranges from 0.1C to 1C.

10. The charging and discharging device according to claim 1 , wherein a ratio of the first cumulative discharge amount threshold to the first cumulative charge amount threshold is less than or equal to 10%.

11. A method for charging a battery, is the method being applied to a charging and discharging device comprising a first direct current/direct current (DC/DC) converter, a unidirectional alternating current/direct current (AC/DC) converter, the first DC/DC converter being a unidirectional DC/DC converter, and comprising:

receiving a first charging current sent by a battery management system (BMS) of a battery, and controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through an alternative current (AC) power source based on the first charging current;

receiving a first discharging current sent by the BMS, and controlling the battery to release power based on the first discharging current, wherein the first discharging current is a discharging current sent by the BMS when a first cumulative charge amount of the battery is greater than or equal to a first cumulative charge amount threshold and a voltage of a battery cell of the battery does not exceed a full charge voltage of the battery cell; and

receiving a second charging current sent by the BMS, and controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current, wherein the second charging current is a charging current sent by the BMS when a first cumulative discharge amount of the battery is greater than or equal to a first cumulative discharge amount threshold.

12. The method according to claim 11 , wherein the method further comprises:

receiving a second discharging current sent by the BMS, and controlling the battery to release power based on the second discharging current, wherein the second discharging current is a discharging current sent by the BMS when a second cumulative charge amount of the battery is greater than or equal to a second cumulative charge amount threshold and the voltage of the battery cell of the battery does not exceed the full charge voltage of the battery cell.

13. The method according to claim 11 , wherein the method further comprises:

receiving a charge stop command sent by the BMS; and

controlling, based on the charge stop command, the unidirectional AC/DC converter and the first DC/DC converter to cause the AC power source to stop charging the battery, wherein the charge stop command is a command sent by the BMS when the voltage of the battery cell of the battery exceeds the full charge voltage.

14. The method according to claim 11 , wherein the charging and discharging device further comprises a second DC/DC converter, and wherein the controlling the battery to release power based on the first discharging current comprises:

controlling, based on the first discharging current, the second DC/DC converter to release the power of the battery into an energy storage unit.

15. The method according to claim 14 , wherein the second DC/DC converter is a bidirectional DC/DC converter, and wherein method further comprises:

controlling the second DC/DC converter to charge the battery through the energy storage unit while controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the first charging current; and/or

controlling the second DC/DC converter to charge the battery through the energy storage unit while controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current.

16. The method according to claim 15 , wherein a first charging power of the energy storage unit to charge the battery is determined according to a discharge capability of the energy storage unit, and a second charging power of the AC power source to charge the battery is a difference between a charging demand power of the battery and the first charging power.

17. The method according to claim 15 , wherein the charging the battery comprises:

acquiring a battery state of charge (SOC) of the energy storage unit;

under a condition that the SOC is greater than a SOC threshold, controlling the second DC/DC converter to charge the battery through the energy storage unit, and controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the first charging current; and/or

under a condition that the SOC is greater than a SOC threshold, controlling the second DC/DC converter to charge the battery through the energy storage unit, and controlling the unidirectional AC/DC converter and the first DC/DC converter to charge the battery through the AC power source based on the second charging current.

18. The method according to claim 11 , wherein a charging rate of the first charging current and/or the second charging current ranges from 2C to 10C.

19. The method according to claim 11 , wherein a discharging rate of the first discharging current ranges from 0.1C to 1C, and a ratio of the first cumulative discharge amount threshold to the first cumulative charge amount threshold is less than or equal to 10%.

20. A charging and discharging device, comprising: a processor and a memory, the memory being configured to store a computer program, and the processor being configured to call the computer program to execute the method for charging the battery of claim 11 .