Parallel hybrid electric vehicle power management system and adaptive power management method and program therefor

Abstract

A system, computer readable storage device and method for controlling torque in a hybrid electric vehicle are disclosed. The method comprises determining a state of charge of an energy storage device, obtaining a reference state of charge, obtaining an error from a difference between the determined state of charge and the reference state of charge; and apportioning torque between a motor and an engine based upon the error. The motor is electrically coupled to the energy storage device and powered by the energy storage device. A state of charge (SOC) correction factor is determined based upon the error. The SOC correction factor is used to adjust a torque ratio of motor to engine torque that is determined for a given torque command.

What is claimed is: 
     
         1 . A method for controlling torque in a hybrid electric vehicle comprising:
 determining a state of charge of an energy storage device;   obtaining a reference state of charge;   obtaining an error from a difference between said determined state of charge and said reference state of charge; and   apportioning torque between a motor and an engine based upon said error, said motor being electrically coupled to said energy storage device and powered by said energy storage device.   
     
     
         2 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , wherein said reference state of charge is constant. 
     
     
         3 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , wherein said reference state of charge is calculated using a reference plant model. 
     
     
         4 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , further comprising: obtaining a state of charge correction factor based upon said error. 
     
     
         5 . The method for controlling torque in a hybrid electric vehicle according to  claim 4 , further comprising: receiving a torque command and wherein said apportioning between said motor and said engine comprises:
 determining a ratio of power from said motor and power from said engine based upon said received torque command; and   adjusting said ratio based upon said state of charge correction factor.   
     
     
         6 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , further comprising:
 charging said energy storage device using only regenerative braking, said charging resulting in an increase in a state of charge for said energy storage device.   
     
     
         7 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , wherein said motor uses only said charged energy from said regenerative braking without charging said energy storage device with power from said engine. 
     
     
         8 . The method for controlling torque in a hybrid electric vehicle according to  claim 4 , further comprising: receiving a torque command and wherein said apportioning of torque between said motor and said engine comprises:
 determining a torque contribution from said motor and from said engine based upon said received torque command; and   adjusting said motor torque contribution based upon said state of charge correction factor.   
     
     
         9 . The method for controlling torque in a hybrid electric vehicle according to  claim 4 , further comprising:
 storing said state of charge correction factor.   
     
     
         10 . The method for controlling torque in a hybrid electric vehicle according to  claim 9 , wherein said stored state of charge correction factor is associated with a type of drive cycle. 
     
     
         11 . The method for controlling torque in a hybrid electric vehicle according to  claim 10 , further comprising:
 receiving a reset request indicating a reset condition, said reset request including a new type of drive cycle;   retrieving a state of charge correction factor associated with the new type of drive cycle;   setting the state of charge correction factor to the retrieved state of charge correction factor; and   adjusting said motor torque contribution based upon said set state of charge correction factor.   
     
     
         12 . The method for controlling torque in a hybrid electric vehicle according to  claim 1 , further comprising:
 monitoring at least one operating parameter for said hybrid electric vehicle; and   adjusting the reference state of charge based upon said monitored at least one operating parameter.   
     
     
         13 . The method for controlling torque in a hybrid electric vehicle according to  claim 5 , further comprising:
 monitoring at least one operating parameter for said hybrid electric vehicle; and   adjusting the obtained state of charge correction factor based upon said monitored at least one operating parameter.   
     
     
         14 . A computer readable storage device storing a computer readable program for causing a computer to execute a method for controlling the torque in a hybrid electric vehicle, said method comprising:
 determining a state of charge of an energy storage device;   obtaining a reference state of charge;   obtaining an error from a difference between said determined state of charge and said reference state of charge; and   apportioning torque between a motor and an engine based upon said error, said motor being electrically coupled to said energy storage device and powered by said energy storage device.   
     
     
         15 . A torque control system comprising:
 a combustion engine;   an energy storage device;   a motor controller coupled to said energy storage device;   a motor/generator coupled to said motor controller; and   a system controller for apportioning torque between said motor/generator and said combustion engine based upon a difference between a determined state of charge of said energy storage device and a reference state of charge, said motor controller controls said motor/generator based upon using power from said energy storage device.