Battery self-heating control method and system, and electric vehicle

A system for self-heating a battery pack, comprising the battery pack, a motor, and a motor controller;

• the motor controller electrically connected to the motor and the battery pack, and the motor electrically connected to the battery pack;
• the motor controller comprising a bridge arm inverter structure, the bridge arm inverter structure comprising an upper bridge arm assembly and a lower bridge arm assembly connected to each other, the upper bridge arm assembly connected to a positive electrode of the battery pack, and the lower bridge arm assembly connected to a negative electrode of the battery pack;
• the battery pack comprising a first battery pack and a second battery pack connected to each other, a first connecting wire led out between the first battery pack and the second battery pack, a first end of the motor connected between the upper bridge arm assembly and the lower bridge arm assembly, and a second end of the motor electrically connected to the battery pack through the first connecting wire;
• and
• the motor controller configured to:
• in a first period of each of control periods, configure a conduction state of the upper bridge arm assembly and a conduction state of the lower bridge arm assembly to be a self- heating state, wherein:
• the self-heating state comprises a first state, a second state, a third state, and a fourth state;
• at a first frequency, the motor controller is configured to switch the conduction state of the upper bridge arm assembly between the first state and the second state;
• and at a second frequency, the motor controller is configured to switch the conduction state of the lower bridge arm assembly between the fourth state and the third state;
• and
• in the self-heating state, alternately charge and discharge the first battery pack or the second battery pack to heat the battery pack by a current on a second connecting wire between the motor and the battery pack.

An electric vehicle, comprising a system for self-heating a battery pack, the system comprising the battery pack, a motor, and a motor controller;

• the motor controller electrically connected to the motor and the battery pack, and the motor electrically connected to the battery pack;
• the motor controller comprising a bridge arm inverter structure, the bridge arm inverter structure comprising an upper bridge arm assembly and a lower bridge arm assembly connected to each other, the upper bridge arm assembly connected to a positive electrode of the battery pack, and the lower bridge arm assembly connected to a negative electrode of the battery pack;
• the battery pack comprising a first battery pack and a second battery pack connected to each other, a first connecting wire led out between the first battery pack and the second battery pack, a first end of the motor connected between the upper bridge arm assembly and the lower bridge arm assembly, and a second end of the motor electrically connected to the battery pack through the first connecting wire;
• and
• the motor controller configured to:
• in a first period of each of control periods, configure a conduction state of the upper bridge arm assembly and a conduction state of the lower bridge arm assembly to be a self-heating state, wherein:
• the self-heating state comprises a first state, a second state, a third state, and a fourth state;
• at a first frequency, the motor controller is configured to switch the conduction state of the upper bridge arm assembly between the first state and the second state;
• and at a second frequency, the motor controller is configured to switch the conduction state of the lower bridge arm assembly between the fourth state and the third state;
• and
• in the self-heating state, alternately charge and discharge the first battery pack and/or or the second battery pack to heat the battery pack by a current on a second connecting wire between the motor and the battery pack.