METHOD AND DEVICE FOR CHARGING AND DISCHARGING BATTERY SYSTEM, BATTERY SYSTEM AND ELECTRIC VEHICLE

1 . A method for charging and discharging a battery system, wherein the battery system comprises a low-voltage battery and a high-voltage battery, wherein the high-voltage battery and the low-voltage battery are both configured to be connected with a load, and the method comprises:

obtaining a first power of the load when the load is in operation;

obtaining a first SOC value of the low-voltage battery and a second SOC value of the high-voltage battery; and

controlling charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value.

2 . The method according to claim 1 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value comprises:

controlling the high-voltage battery to discharge for the load, or alternatively, controlling the high-voltage battery and the low-voltage battery to discharge simultaneously for the load, if a maximum power output by the low-voltage battery is smaller than the first power.

3 . The method according to claim 2 , wherein when the high-voltage battery and the low-voltage battery are controlled to discharge simultaneously for the load, and if the first SOC value is smaller than or equal to a first SOC threshold, the low-voltage battery is controlled to stop discharging for the load.

4 . The method according to claim 1 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value comprises:

controlling the low-voltage battery to discharge for the load if a maximum power output by the low-voltage battery is greater than or equal to the first power; and

controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value.

5 . The method according to claim 4 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value comprises:

controlling the low-voltage battery to discharge for the load if the first SOC value is greater than a second SOC threshold and the first SOC value is smaller than or equal to a third SOC threshold.

6 . The method according to claim 5 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value further comprises:

controlling the high-voltage battery to discharge for the load if the first SOC value is smaller than or equal to the second SOC threshold, and the second SOC value is greater than a fourth SOC threshold; and

controlling the high-voltage battery to charge the low-voltage battery until a SOC value of the low-voltage battery reaches the third SOC threshold.

7 . The method according to claim 5 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value further comprises:

outputting a prompt for charging the high-voltage battery and the low-voltage battery if the first SOC value is smaller than or equal to the second SOC threshold and the second SOC value is smaller than or equal to the fourth SOC threshold.

8 . The method of claim 1 , wherein the method further comprises:

controlling the low-voltage battery to discharge for the load upon receiving a high-voltage power-down signal.

9 . The method according to claim 1 , wherein the battery system further comprises a bidirectional DC/DC module, the bidirectional DC/DC module is respectively connected with the high-voltage battery and the low-voltage battery, and the method further comprises:

controlling the bidirectional DC/DC module to enable the high-voltage battery to charge the low-voltage battery, or enable the low-voltage battery to charge the high-voltage battery, or enable the high-voltage battery to discharge for the load.

10 . A device for charging and discharging a battery system, wherein the battery system comprises a low-voltage battery and a high-voltage battery, wherein the high-voltage battery and the low-voltage battery are both configured to be connected with a load, and the device comprises:

a power acquisition unit, configured to obtain a first power of the load when the load is in operation;

an SOC value acquisition unit, configured to obtain a first SOC value of the low-voltage battery and a second SOC value of the high-voltage battery; and

a charge-and-discharge controller, configured to control charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value.

11 . The device according to claim 10 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value comprises:

controlling the high-voltage battery to discharge for the load, or alternatively, controlling the high-voltage battery and the low-voltage battery to discharge simultaneously for the load, if a maximum power output by the low-voltage battery is smaller than the first power.

12 . The device according to claim 11 , wherein when the high-voltage battery and the low-voltage battery are controlled to discharge simultaneously for the load, and if the first SOC value is smaller than or equal to a first SOC threshold, the low-voltage battery is controlled to stop discharging for the load.

13 . The device according to claim 10 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first power, the first SOC value and the second SOC value comprises:

controlling the low-voltage battery to discharge for the load if a maximum power output by the low-voltage battery is greater than or equal to the first power; and

controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value.

14 . The device according to claim 13 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value comprises:

controlling the low-voltage battery to discharge for the load if the first SOC value is greater than a second SOC threshold and the first SOC value is smaller than or equal to a third SOC threshold.

15 . The device according to claim 14 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value further comprises:

controlling the high-voltage battery to discharge for the load if the first SOC value is smaller than or equal to the second SOC threshold, and the second SOC value is greater than a fourth SOC threshold; and

controlling the high-voltage battery to charge the low-voltage battery until a SOC value of the low-voltage battery reaches the third SOC threshold.

16 . The device according to claim 14 , wherein said controlling the charge-and-discharge processes of the high-voltage battery and the low-voltage battery according to the first SOC value and the second SOC value further comprises:

outputting a prompt for charging the high-voltage battery and the low-voltage battery if the first SOC value is smaller than or equal to the second SOC threshold and the second SOC value is smaller than or equal to the fourth SOC threshold.

17 . The device according to claim 1 , wherein the charge-and-discharge controller further configured to:

control the low-voltage battery to discharge for the load upon receiving a high-voltage power-down signal.

18 . The device according to claim 10 , wherein the battery system further comprises a bidirectional DC/DC module, the bidirectional DC/DC module is respectively connected with the high-voltage battery and the low-voltage battery, and the charge-and-discharge controller further configured to:

control the bidirectional DC/DC module to enable the high-voltage battery to charge the low-voltage battery, or enable the low-voltage battery to charge the high-voltage battery, or enable the high-voltage battery to discharge for the load.

19 . An electric vehicle, comprising:

a load; and

a battery system, the battery system comprising:

a low-voltage battery;

a high-voltage battery;

a bidirectional DC/DC module; and

a master controller, the master controller comprising a memory; and a processor, coupled to the memory, wherein the processor is configured to perform the method according to claim 1 based on an instruction stored in the memory,

wherein the master controller is respectively connected with the low-voltage battery, the high-voltage battery and the bidirectional DC/DC module, and

wherein the battery system is configured to supply power to the load.

20 . The electric vehicle according to claim 19 , wherein the master controller comprises a vehicle controller, a low-voltage battery controller, a logic controller of a bidirectional DC/DC module, and a high-voltage battery controller;

the vehicle controller is configured to control the low-voltage battery controller, the logic controller of the bidirectional DC/DC module and the high-voltage battery controller, the low-voltage battery controller is configured to control a charge-and-discharge process of the low-voltage battery, the logic controller of the bidirectional DC/DC module is configured to control the bidirectional DC/DC module, and a high-voltage battery controller is configured to control the charge-and-discharge process of the high-voltage battery.