Vehicle energy-storage systems
Systems and methods for storing energy for use by an electric vehicle are disclosed. Systems can include an electric vehicle battery pack including a rack configured to couple a plurality of independently removable battery strings to the vehicle, the battery strings configured to be selectively coupled in parallel to a vehicle power bus. The battery strings may include a housing, a plurality of electrochemical cells disposed within the housing, a circuit for electrically connecting the electrochemical cells, a positive high-voltage connector, a negative high-voltage connector, a switch within the housing, and a string control unit configured to control the switch. Each battery string can include a coolant inlet and a coolant outlet configured to couple with and sealingly uncouple from an external coolant supply conduit and an external coolant return conduit, and an auxiliary connector configured to couple with an external communications system and/or an external low-voltage power supply.
1. An electric vehicle battery pack comprising:
a rack configured to couple a plurality of independently removable battery strings to the vehicle, the battery strings selectively coupled in parallel to a vehicle power bus, individual battery strings of the plurality of battery strings comprising:
an individual battery string housing;
a plurality of electrochemical cells disposed within the housing;
a circuit for electrically connecting the plurality of electrochemical cells, the circuit having a positive terminal and a negative terminal;
a positive high-voltage connector located on an exterior surface of the housing, the positive high-voltage connector electrically coupled to the positive terminal;
a negative high-voltage connector located on an exterior surface of the housing, the negative high-voltage connector electrically coupled to the negative terminal;
a switch disposed within the housing and electrically connected in series with at least the positive high-voltage connector; and
a string control unit disposed within the housing, the string control unit electrically coupled to and configured to control the switch; and
a battery pack controller in communication with the string control units and one or more other components of the vehicle;
wherein each battery string comprises a plurality of battery modules connected in series, each battery module comprising a plurality of electrochemical cells;
wherein each battery string further comprises a plurality of module monitoring boards, each module monitoring board communicatively coupled to the string control unit and to one of the plurality of battery modules and configured to monitor at least one of a current, a voltage, and a temperature associated with the one battery module; and
wherein the battery pack controller comprises one or more processors and memory storing instructions that, when executed by the one or more processors, cause the one or more processors to:
receive, from a string control unit of an individual battery string or from the one or more other components of the vehicle, a signal indicating a fault condition;
determine, based on the signal, whether the fault condition is a first type of fault condition for which the individual battery string should be disconnected or a second type of fault condition for which all of the battery strings should be disconnected;
cause actuation of the switch of the individual battery string to disconnect the individual battery string from the vehicle power bus while at least one other individual battery string continues providing power to the vehicle power bus when the fault condition is the first type of fault condition; and
cause actuation of the switches of all of the battery strings to disconnect all of the battery strings from the vehicle power bus when the fault condition is the second type of fault condition.
2. The electric vehicle battery pack of claim 1 , wherein each battery string further comprises:
a coolant inlet located on an exterior surface of the housing and configured to couple with and sealingly uncouple from an external coolant supply conduit;
a coolant outlet located on an exterior surface of the housing and configured to couple with and sealingly uncouple from an external coolant return conduit; and
an auxiliary connector located on an exterior surface of the housing and configured to couple with at least one of an external communications system and an external low-voltage power supply.
3. The electric vehicle battery pack of claim 2 , wherein the auxiliary connector comprises a CAN bus connector configured to couple with a CAN bus.
4. The electric vehicle battery pack of claim 2 , further comprising one or more thermal barriers configured to at least partially insulate adjacent battery strings.
5. The electric vehicle battery pack of claim 1 , wherein the switch comprises a magnetic contactor configured to be in a disconnected position when the magnetic contactor is not energized.
6. An electric vehicle battery pack comprising:
a rack configured to couple a plurality of independently removable battery strings to the vehicle, the battery strings selectively coupled in parallel to a vehicle power bus, individual battery strings of the plurality of battery strings comprising:
an individual battery string housing;
a plurality of electrochemical cells disposed within the housing;
a circuit for electrically connecting the plurality of electrochemical cells, the circuit having a positive terminal and a negative terminal;
a positive high-voltage connector located on an exterior surface of the housing, the positive high-voltage connector electrically coupled to the positive terminal;
a negative high-voltage connector located on an exterior surface of the housing, the negative high-voltage connector electrically coupled to the negative terminal;
a coolant inlet located on an exterior surface of the housing and configured to couple with and sealingly uncouple from an external coolant supply conduit;
a coolant outlet located on an exterior surface of the housing and configured to couple with and sealingly uncouple from an external coolant return conduit;
a string control unit configured to selectively cause disconnection of the battery string from the vehicle power bus; and
an auxiliary connector located on an exterior surface of the housing and configured to couple with at least one of an external communications system and an external low-voltage power supply; and
a battery pack controller in communication with the string control units and one or more other components of the vehicle;
wherein each battery string comprises a plurality of battery modules connected in series, each battery module comprising a plurality of electrochemical cells;
wherein each battery string further comprises a plurality of module monitoring boards, each module monitoring board communicatively coupled to the string control unit and to one of the plurality of battery modules and configured to monitor at least one of a current, a voltage, and a temperature associated with the one battery module; and
wherein the battery pack controller comprises one or more processors and memory storing instructions that, when executed by the one or more processors, cause the one or more processors to:
receive, from a string control unit of an individual battery string or from the one or more other components of the vehicle, a signal indicating a fault condition;
determine, based on the signal, whether the fault condition is a first type of fault condition for which the individual battery string should be disconnected or a second type of fault condition for which all of the battery strings should be disconnected;
cause disconnection of the individual battery string from the vehicle power bus while at least one other individual battery string continues providing power to the vehicle power bus when the fault condition is the first type of fault condition; and
cause disconnection of all of the battery strings from the vehicle power bus when the fault condition is the second type of fault condition.
7. The electric vehicle battery pack of claim 6 , wherein each battery string further comprises a switch disposed within the housing and electrically connected in series with at least the positive terminal.
8. The electric vehicle battery pack of claim 7 , wherein the string control unit of each battery string is disposed within the housing, the string control unit electrically coupled to and configured to control the switch.
9. The electric vehicle battery pack of claim 8 , wherein the auxiliary connector is configured to couple with the external low-voltage power supply, and wherein the string control unit is configured to draw electrical power from the auxiliary connector.
10. The electric vehicle battery pack of claim 6 , wherein the auxiliary connector comprises a CAN bus connector configured to connect to a CAN bus.
11. The electric vehicle battery pack of claim 6 , further comprising one or more thermal barriers configured to at least partially insulate adjacent battery strings.