Method for equalizing the voltage of traction battery modules of a hybrid electric vehicle

Claim 1

A method for tending to equalize the voltages of the modules of a traction battery of a hybrid electric vehicle, which traction battery is made up of a plurality of series-connected modules, said method being performed by a programmed processor, and comprising the steps of: while said vehicle is in operation, sensing the voltages of each of said modules under conditions approximating a selected load condition, to thereby produce sensed module voltages; at least temporarily storing a representation of said sensed module voltages to thereby produce stored sensed module voltages; sorting at least some of said voltages into at least one ordered ranking; selecting from said at least one ordered ranking one of said modules which has a stored sensed voltage near the maximum of said ranking, to thereby identify a high module; selecting from said at least one ordered ranking another one of said modules which has a stored sensed voltage near the minimum of said ranking, to thereby identify a low module; and partially discharging said high module, and coupling the energy made available by said partial discharging to charge said low module.

Claim 2

A method for tending to equalize the voltages of the modules of a traction battery of a hybrid electric vehicle, which traction battery is made up of a plurality of series-connected modules, said method being performed by a programmed processor, and comprising the steps of: while said vehicle is in operation, sensing the voltages of each of said modules under conditions approximating a selected load condition, to thereby produce sensed module voltages; at least temporarily storing a representation of said sensed module voltages to thereby produce stored sensed module voltages; sorting at least some of said voltages into at least one ordered ranking; selecting from said at least one ordered ranking one of said modules which has a stored sensed voltage near the maximum of said ranking, to thereby identify a high module; selecting from said at least one ordered ranking another one of said modules which has a stored sensed voltage near the minimum of said ranking, to thereby identify a low module; and partially discharging said high module, and coupling the energy made available by said partial discharging to charge said low module.

Claim 7

A method for determining if a module is defective, where the module is series-connected in a battery subject to an intermittent discharge load and intermittent charging, both at varying current, said method comprising the steps of: while said battery is supplying load current at a significant fraction of its full-load capability, sensing the voltages of each of said modules, to thereby produce sensed module discharge voltages; at least temporarily storing a representation of said sensed module discharge voltages to thereby produce stored module discharge voltages; sorting at least some of said stored module discharge voltages into a first ordered ranking; while said battery is receiving charging current at a significant fraction of its maximum charging capability, sensing the voltages of each of said modules, to thereby produce sensed module charge voltages; at least temporarily storing a representation of said sensed module charge voltages to thereby produce stored module charge voltages; sorting at least some of said stored module charge voltages into a second ordered ranking; selecting from said at first ordered ranking one of said modules which has a stored discharge voltage near the minimum of said first ranking, to thereby identify a low module; averaging said stored module discharge voltages to produce an average module discharge voltage; averaging said stored module charge voltages to produce an average module charge voltage; taking the difference between said stored discharge voltage of said low module and said average module discharge voltage, to produce a low module discharge voltage difference; comparing said low module discharge voltage difference with a threshold value, and deeming said low module to have a first indicium of a bad module if said low module discharge voltage difference exceeds said threshold; taking the difference between said stored charge voltage of said low module and said average module charge voltage, to produce a low module charge voltage difference; comparing said low module charge voltage difference with a threshold value, and deeming said low module to have a second indicium of a bad module if said low module charge voltage difference exceeds said threshold; determining where, within said second ranking, said stored charge voltage of said low module occurs, and if it occurs within a specified region of said ranking, deeming said low module to have a third indicium of a bad module; and deeming said low module to be defective if said first, second, and third indicia of a bad module coexist.

Claim 8

A method for determining if a module is defective, where the module is series-connected in a battery subject to an intermittent discharge load and intermittent charging, both at varying current, said method comprising the steps of: while said battery is supplying load current at a significant fraction of its full-load capability, sensing the voltages of each of said modules, to thereby produce sensed module discharge voltages; at least temporarily storing a representation of said sensed module discharge voltages to thereby produce stored module discharge voltages; sorting at least some of said stored module discharge voltages into a first ordered ranking; while said battery is receiving charging current at a significant fraction of its maximum charging capability, sensing the voltages of each of said modules, to thereby produce sensed module charge voltages; at least temporarily storing a representation of said sensed module charge voltages to thereby produce stored module charge voltages; sorting at least some of said stored module charge voltages into a second ordered ranking; selecting from said at first ordered ranking one of said modules which has a stored discharge voltage near the minimum of said first ranking, to thereby identify a low module; averaging said stored module discharge voltages to produce an average module discharge voltage; averaging said stored module charge voltages to produce an average module charge voltage; taking the difference between said stored discharge voltage of said low module and said average module discharge voltage, to produce a low module discharge voltage difference; comparing said low module discharge voltage difference with a threshold value, and deeming said low module to have a first indicium of a bad module if said low module discharge voltage difference exceeds said threshold; taking the difference between said stored charge voltage of said low module and said average module charge voltage, to produce a low module charge voltage difference; comparing said low module charge voltage difference with a threshold value, and deeming said low module to have a second indicium of a bad module if said low module charge voltage difference exceeds said threshold; determining where, within said second ranking, said stored charge voltage of said low module occurs, and if it occurs within a specified region of said ranking, deeming said low module to have a third indicium of a bad module; and deeming said low module to be defective if said first, second, and third indicia of a bad module coexist.

Claim 10

A method for determining if a module is defective, where the module is series-connected in a battery subject to an intermittent discharge load and intermittent charging, both at varying current, said method comprising the steps of: while said battery is supplying load current at a significant fraction of its full-load capability, sensing the voltages of each of said modules, to thereby produce sensed module discharge voltages; at least temporarily storing a representation of said sensed module discharge voltages to thereby produce stored module discharge voltages; sorting at least some of said stored module discharge voltages into a first ordered ranking; while said battery is receiving charging current at a significant fraction of its maximum charging capability, sensing the voltages of each of said modules, to thereby produce sensed module charge voltages; at least temporarily storing a representation of said sensed module charge voltages to thereby produce stored module charge voltages; sorting at least some of said stored module charge voltages into a second ordered ranking; selecting from said second ordered ranking another one of said modules which has a stored charge voltage near the maximum of said ranking, to thereby identify a high module; averaging said stored module discharge voltages to produce an average module discharge voltage; averaging said stored module charge voltages to produce an average module charge voltage; taking the difference between said stored discharge voltage of said high module and said average module discharge voltage, to produce a high module discharge voltage difference; comparing said high module discharge voltage difference with a threshold value, and deeming said high module to have a first indicium of a bad module if said high module discharge voltage difference exceeds said threshold; taking the difference between said stored charge voltage of said high module and said average module charge voltage, to produce a high module charge voltage difference; comparing said high module charge voltage difference with a threshold value, and deeming said high module to have a second indicium of a bad module if said high module charge voltage difference exceeds said threshold; determining where, within said first ranking, said stored discharge voltage of said high module occurs, and if it occurs within a specified region of said first ranking, deeming said high module to have a third indicium of a bad module; and deeming said high module to be defective if said first, second, and third indicia of a bad module coexist.

Claim 11

A method for determining if a module is defective, where the module is series-connected in a battery subject to an intermittent discharge load and intermittent charging, both at varying current, said method comprising the steps of: while said battery is supplying load current at a significant fraction of its full-load capability, sensing the voltages of each of said modules, to thereby produce sensed module discharge voltages; at least temporarily storing a representation of said sensed module discharge voltages to thereby produce stored module discharge voltages; sorting at least some of said stored module discharge voltages into a first ordered ranking; while said battery is receiving charging current at a significant fraction of its maximum charging capability, sensing the voltages of each of said modules, to thereby produce sensed module charge voltages; at least temporarily storing a representation of said sensed module charge voltages to thereby produce stored module charge voltages; sorting at least some of said stored module charge voltages into a second ordered ranking; selecting from said second ordered ranking another one of said modules which has a stored charge voltage near the maximum of said ranking, to thereby identify a high module; averaging said stored module discharge voltages to produce an average module discharge voltage; averaging said stored module charge voltages to produce an average module charge voltage; taking the difference between said stored discharge voltage of said high module and said average module discharge voltage, to produce a high module discharge voltage difference; comparing said high module discharge voltage difference with a threshold value, and deeming said high module to have a first indicium of a bad module if said high module discharge voltage difference exceeds said threshold; taking the difference between said stored charge voltage of said high module and said average module charge voltage, to produce a high module charge voltage difference; comparing said high module charge voltage difference with a threshold value, and deeming said high module to have a second indicium of a bad module if said high module charge voltage difference exceeds said threshold; determining where, within said first ranking, said stored discharge voltage of said high module occurs, and if it occurs within a specified region of said first ranking, deeming said high module to have a third indicium of a bad module; and deeming said high module to be defective if said first, second, and third indicia of a bad module coexist.