Wireless battery management systems using variable frame length

Abstract

A monitor circuit for use in a management system with modular subsystems includes: a sensor configured to measure parameter values of a monitored electrical component as a function of time; and storage coupled to the sensor and configured to store the parameter values. The monitor circuit also includes frame preparation circuitry coupled to the storage and configured to prepare frames that include the parameter values, wherein the prepared frames vary in length as a function of time.

What is claimed is: 
     
         1 . A device in a wireless battery management system (WBMS), the device comprising:
 a sensor configured to measure parameter values of one or more battery cells;   storage coupled to the sensor and configured to store the parameter values;   a communication interface configured to receive a first command from a primary node in the WBMS; and   frame preparation circuitry coupled to the storage and configured to prepare a first frame that include the parameter values,   wherein the frame preparation circuitry is configured to set a first length of the first frame based on the first command.   
     
     
         2 . The device of  claim 1 , wherein the first command indicates the first length for the first frame. 
     
     
         3 . The device of  claim 1 , wherein the frame preparation circuitry is configured to set the first length of the first frame based on a value in a payload section of the first command. 
     
     
         4 . The device of  claim 1 ,
 wherein the first command includes a command to read a number of bytes, and   wherein the first length is equal to the number of bytes.   
     
     
         5 . The device of  claim 1 ,
 wherein the first frame includes a fixed payload portion and a variable payload portion, and   wherein the frame preparation circuitry is configured to set the first length of the first frame by setting a length of the variable payload portion of the first frame based on the first command.   
     
     
         6 . The device of  claim 5 , wherein the frame preparation circuitry is configured to set the length of the variable payload portion by adding dummy reads to the first frame. 
     
     
         7 . The device of  claim 1 ,
 wherein the communication interface is further configured to receive a second command from the primary node,   wherein the frame preparation circuitry is further configured to prepare a second frame including a second length based on the second command, and   wherein the first length is different from the second length.   
     
     
         8 . The device of  claim 7 ,
 wherein the first command indicates the first length for the first frame, and   wherein the second command indicates the second length for the second frame.   
     
     
         9 . The device of  claim 7 , wherein the frame preparation circuitry is configured to:
 set the first length of the first frame based on a first value in a payload section of the first command;   set the second length of the second frame based on a second value in a payload section of the second command.   
     
     
         10 . The device of  claim 7 ,
 wherein the first command includes a command to read a first number of bytes,   wherein the second command includes a command to read a second number of bytes,   wherein the first length is equal to the first number of bytes,   wherein the second length is equal to the second number of bytes   
     
     
         11 . The device of  claim 7 ,
 wherein the first frame includes a first fixed payload portion and a first variable payload portion,   wherein the second frame includes a second fixed payload portion and a second variable payload portion,   wherein a length of the second fixed payload portion is equal to a length of the first fixed payload portion, and   wherein the frame preparation circuitry is configured to:
 set the first length of the first frame by setting a length of the first variable payload portion of the first frame based on the first command; and 
 set the second length of the second frame by setting a length of the second variable payload portion of the second frame based on the second command. 
   
     
     
         12 . The device of  claim 11 , wherein the frame preparation circuitry is configured to:
 set the length of the first variable payload portion by adding dummy reads to the first frame; and   set the length of the second variable payload portion without adding dummy reads to the second frame.   
     
     
         13 . A wireless battery management system (WBMS) comprising:
 a primary controller configured to transmit a first command;   a secondary node configured to:
 measure parameter values of one or more battery cells; 
 prepare a first frame that includes the parameter values; and 
 set a first length of the first frame based on the first command. 
   
     
     
         14 . The WBMS of  claim 13 ,
 wherein the first frame includes a fixed payload portion and a variable payload portion, and   wherein the secondary node is configured to set the first length of the first frame by setting a length of the variable payload portion of the first frame based on the first command.   
     
     
         15 . The WBMS of  claim 14 , wherein the secondary node is configured to set the length of the variable payload portion by adding dummy reads to the first frame. 
     
     
         16 . The WBMS of  claim 13 ,
 wherein the primary controller is further configured to transmit a second command to the secondary node,   wherein the secondary node is further configured to prepare a second frame including a second length based on the second command, and   wherein the first length is different from the second length.   
     
     
         17 . The WBMS of  claim 16 ,
 wherein the first frame includes a first fixed payload portion and a first variable payload portion,   wherein the second frame includes a second fixed payload portion and a second variable payload portion,   wherein a length of the second fixed payload portion is equal to a length of the first fixed payload portion, and   wherein the secondary node is configured to:
 set the first length of the first frame by setting a length of the first variable payload portion of the first frame based on the first command, and 
 set the second length of the second frame by setting a length of the second variable payload portion of the second frame based on the second command. 
   
     
     
         18 . A method comprising:
 measuring, by a secondary node in a wireless battery management system (WBMS), parameter values of one or more battery cells;   receiving, by the secondary node, a first command from a primary node in the WBMS;   preparing, by the secondary node, a first frame that includes the parameter values; and   setting, by the secondary node, a first length of the first frame based on the first command.   
     
     
         19 . The method of  claim 18 , further comprising:
 receiving a second command from the primary node; and   preparing a second frame including a second length based on the second command,   wherein the first length is different from the second length.   
     
     
         20 . The method of  claim 19 ,
 wherein the first frame includes a first fixed payload portion and a first variable payload portion,   wherein the second frame includes a second fixed payload portion and a second variable payload portion,   wherein a length of the second fixed payload portion is equal to a length of the first fixed payload portion, and   wherein the method further comprises:
 setting the first length of the first frame by setting a length of the first variable payload portion of the first frame based on the first command; and 
 setting the second length of the second frame by setting a length of the second variable payload portion of the second frame based on the second command.