Enhanced switched balancing network for battery pack

Abstract

One or more of the present embodiments provide for a battery cell balancing system and strategy that delivers more efficient use of battery capacities as needed for different use cases. For example, a balancing circuit is provided to support targeted battery cell passive and active balancing according to a balancing strategy for the use cases. Further the balancing circuit allows for cell balancing to be performed while the battery cells are collectively being charged or discharged.

We claim: 
     
         1 . A balancing circuit comprising:
 a cell group stack comprising:
 a plurality of cell groups; 
 a plurality of cell group balancing relays, each of the cell group balancing relays electrically coupled to one of the cell groups; 
 a charge balancing relay configured to selectively electrically couple a voltage source to the plurality of cell group balancing relays; 
 a discharge balancing relay configured to selectively electrically couple a load and the plurality of cell group balancing relays; and 
 a balancing controller communicatively coupled to the plurality of cell group balancing relays, the charge balancing relay, and the discharge balancing relay, wherein the balancing controller controls open and closed states of the plurality of cell group balancing relays, charge balancing relay, and discharge balancing relay based on a balancing state of the cell group stack. 
   
     
     
         2 . The balancing circuit of  claim 1 , further comprising one or more additional cell group stacks and a power source arranged to deliver electrical power to the cell group stacks. 
     
     
         3 . The balancing circuit of  claim 2 , further comprising a battery management system and a plurality of stack controllers, at least one of the stack controllers communicatively coupled to the battery management system and at least one of the cell group stacks, the at least one of the stack controllers to control the balancing controller of the at least one of the cell group stacks based on an external configuration received from the battery management system. 
     
     
         4 . The balancing circuit of  claim 1 , wherein the balancing state of the cell group stack is selected from the group consisting of a charge balancing state, a discharge balancing state, and a no balance state. 
     
     
         5 . The balancing circuit of  claim 1 , further comprising the voltage source and the load. 
     
     
         6 . The balancing circuit of  claim 1 , wherein the balancing controller is configured to balance the plurality of cell groups based on aggregated data for each of the cell groups. 
     
     
         7 . The balancing circuit of  claim 1 , wherein the balancing controller is configured to balance the plurality of cell groups based on a measured voltage and a measured temperature received for each of the cell groups. 
     
     
         8 . A balancing circuit comprising:
 a plurality of cell groups;   a plurality of cell balance relays;   a plurality of balancing controllers, each balancing controller configured to control charging and discharging for a different subset of the plurality of cell groups;   a plurality of string controllers, each string controller configured to control a different subset of the plurality of balancing controllers; and   a battery management system configured to control power distribution in the balancing circuit by controlling the plurality of string controllers,   wherein each balancing controller controls open and closed states of a subset of the plurality of cell balance relays based on a balancing state of the balancing controller.   
     
     
         9 . The balancing circuit of  claim 8 , further comprising:
 an energy management system configured to control power delivery to the balancing circuit.   
     
     
         10 . The balancing circuit of  claim 9 , wherein the energy management system is configured to control power delivery from a power supply based upon a balancing profile received via an application programming interface (API) from a user device. 
     
     
         11 . The balancing circuit of  claim 8 , wherein the balancing state of each of the balancing controllers is one of in a plurality of states comprising:
 a charge balancing state for charging one of the plurality of cell groups to a target voltage;   a discharge balancing state for discharging one of the plurality of cell groups to a target voltage; and   a no balance state for decoupling a subset of the plurality of cell groups from the balancing circuit.   
     
     
         12 . The balancing circuit of  claim 11 , wherein the balancing controllers are configured to transition to the no balance state before charging or discharging a different cell group. 
     
     
         13 . The balancing circuit of  claim 8 , wherein the balancing circuit is configured to charge or discharge specific cell groups of the plurality of cell groups via the plurality of balancing controllers and the plurality of string controllers. 
     
     
         14 . A balancing circuit comprising:
 a plurality of cell group stacks, each stack comprising:
 a plurality of cell groups; and 
 a plurality of balancing controllers, each balancing controller configured to control a different circuit for balancing a different subset of the plurality of cell groups; and 
   a plurality of stack controllers, each stack controller configured to control a different subset of the plurality of balancing controllers.   
     
     
         15 . The balancing circuit of  claim 14 , further comprising:
 a power supply configured to deliver power to the plurality of cell group stacks;   a battery management system (BMS) configured to control power distribution to the plurality of cell groups by controlling the plurality of stack controllers; and   an energy management system (EMS) configured to control power delivery by the power supply.   
     
     
         16 . The balancing circuit of  claim 15 , wherein each of the plurality of stack controllers is configured to operate based on a balancing mode received from the BMS, wherein the balancing mode comprises a target voltage mode for equalizing voltages of the plurality of cell groups. 
     
     
         17 . The balancing circuit of  claim 16 , wherein the target voltage mode comprises:
 an average mode configured to charge, to discharge, or to charge and discharge one or more of the plurality of cell groups to a target voltage set to an average voltage of the plurality of cell groups; or   a fixed target voltage mode configured to charge, to discharge, or to charge and discharge one or more of the plurality of cell groups to a target voltage set as a fixed voltage for the plurality of cell groups.   
     
     
         18 . The balancing circuit of  claim 16 , wherein the target voltage mode comprises:
 a low target voltage mode configured to charge, to discharge, or to charge and discharge one or more of the plurality of cell groups to a target voltage set to a lowest voltage of the plurality of cell groups; or   a high target voltage mode configured to charge, to discharge, or to charge and discharge one or more of the plurality of cell groups to a target voltage set to a highest voltage of the plurality of cell groups.   
     
     
         19 . The balancing circuit of  claim 16 , wherein the balancing mode includes a charge voltage dead-band configured to ignore cell groups with voltages less than a threshold below a target voltage. 
     
     
         20 . The balancing circuit of  claim 16 , wherein the balancing mode includes a discharge voltage dead-band configured to ignore cell groups having voltages greater than a threshold above a target voltage.