Communication system for battery management systems in electric or hybrid vehicles

Abstract

A circuit can include a CAN bus and multiple nodes. The multiple nodes can reboot at the same time so that a Time 0 is set at boot for each node. Each node can store an ID node and determine from its ID node one time slot of a plurality of periodic time slots starting from Time 0 in which to transmit on the CAN bus. Each node can transmit messages on the CAN bus in its determined time slot subsequent to Time 0.

1 - 30 . (canceled) 
     
     
         31 . A circuit comprising:
 a controller area network (CAN) bus; and   a plurality of nodes each storing a node identifier,   wherein each of the plurality of nodes is configured to send messages over the CAN bus during its assigned periodic time slot and not during other time slots.   
     
     
         32 . The circuit of  claim 31 , wherein each of the plurality of nodes is configured to determine its assigned periodic time slot from an initial time that depends on a reboot time for the plurality of nodes. 
     
     
         33 . The circuit of  claim 32 , wherein each of the plurality of nodes is configured to determine its assigned periodic time slot further from a multiplication of a time constant and a value stored in its memory. 
     
     
         34 . The circuit of  claim 32 , wherein each of the plurality of nodes is configured to determine its assigned periodic time slot further from a multiplication of a time constant and its node identifier. 
     
     
         35 . The circuit of  claim 31 , wherein the plurality of nodes is configured to synchronize a timing for sending the messages. 
     
     
         36 . The circuit of  claim 35 , wherein the plurality of nodes is configured to power at a common power-on time and synchronize relative to the common power-on time. 
     
     
         37 . The circuit of  claim 35 , wherein the plurality of nodes is configured to synchronize relative to a common time other than a reboot time for the plurality of nodes. 
     
     
         38 . The circuit of  claim 31 , wherein one of the plurality of nodes is configured to:
 detect a collision with the message from another node of the plurality of nodes; and   resynchronize responsive to detection of the collision.   
     
     
         39 . The circuit of  claim 38 , wherein the one of the plurality of nodes is configured to resynchronize by rebooting. 
     
     
         40 . The circuit of  claim 31 , further comprising a galvanic isolation between one of the plurality of nodes and the CAN bus. 
     
     
         41 . The circuit of  claim 40 , wherein the galvanic isolation comprises a transformer for power signals and an optocoupler for data signals. 
     
     
         42 . The circuit of  claim 40 , wherein the one of the plurality of nodes comprises a bus driver, and the galvanic isolation is between the bus driver and the CAN bus. 
     
     
         43 . The circuit of  claim 40 , wherein the galvanic isolation is configured to disconnect the one of the plurality of nodes from the CAN bus. 
     
     
         44 . The circuit of  claim 43 , further comprising a numerical circuit in the one of the plurality of nodes, the numerical circuit being configured to control a connection or a disconnection of the galvanic isolation. 
     
     
         45 . The circuit of  claim 43 , further comprising a central control system configured to control a connection or a disconnection of the galvanic isolation. 
     
     
         46 . The circuit of  claim 31 , wherein one of the plurality of nodes comprises a battery management system configured to monitor one or more battery cells in a battery pack. 
     
     
         47 . A system comprising:
 the circuit of  claim 46 ; and   a central monitoring unit connected to the CAN bus, the central monitoring unit being configured to present a state of the one or more battery cells.   
     
     
         48 . A method for sharing a controller area network (CAN) bus between a plurality of nodes, wherein a node identifier is assigned to each of the plurality of nodes, the method comprising:
 dividing a CAN channel into a plurality of periodic time slots;   assigning one of the plurality of periodic time slots to each node; and   sending, by each of the plurality of nodes, messages during its assigned periodic time slot and not during other time slots.   
     
     
         49 . The method of  claim 48 , further comprising synchronizing a timing of the plurality of nodes for sending the messages. 
     
     
         50 . The method of  claim 49 , wherein said synchronizing comprises:
 powering the plurality of nodes at a common power-on time; and   synchronizing the plurality of nodes relative to the common power-on time.   
     
     
         51 . The method of  claim 50 , further comprising:
 detecting a collision between messages sent from the plurality of nodes; and   resynchronizing at least one node of the plurality of nodes from the collision.   
     
     
         52 . The method of  claim 51 , wherein said resynchronizing comprises rebooting the plurality of nodes. 
     
     
         53 . The method of  claim 48 , further comprising setting a reboot time at boot of the plurality of nodes, and wherein said assigning comprises assigning individual time slots of the plurality of periodic time slots to the plurality of nodes based at least on the reboot time and the node identifiers assigned to the plurality of nodes. 
     
     
         54 . The method of  claim 48 , further comprising monitoring, by a battery management system of one of the plurality of nodes, one or more battery cells in a battery pack. 
     
     
         55 . The method of  claim 48 , further comprising rebooting, by a central monitoring unit, the plurality of nodes at least once every first time duration.