Appeal No. 2003-0275 Page 8
Application No. 09/550,032
Brake controller 66 converts the brake pedal pressure signals on lines 84
and 85 to a brake torque command and provides a request on line 60 to motor
controller 22 for regenerative braking. Motor controller 22 continuously runs a
routine (i.e., every 100 ms) to determine the amount of regenerative braking
capable by monitoring rotational speed of motor 18 and by monitoring the
condition of battery pack assembly 10, including the voltage level and current
flow. The amount of regenerative braking capable is determined by the amount
of power that can be generated by motor 18 at its given rotational speed. The
determined amount of regenerative braking capable may be limited by other
factors, such as battery voltage conditions, which indicate the amount of power
that can be transferred to battery pack 10 without harming the electrical system
or battery pack 10, and vehicle speed.
Motor controller 22 then, responsive to the brake regeneration request
and the determined regeneration capability, commands power inverter 12
through line 16 to place motor 18 in a regenerative state and transfer energy to
battery pack 10. The regenerative state of motor 18 provides braking torque to
the vehicle wheels to which motor 18 is connected at a level corresponding to
either (a) the determined regenerative braking capability, or (b) the brake torque
command, whichever is less.
Boberg's teachings
Boberg's invention relates generally to a hybrid electric vehicle and, more
particularly, to an electric motor/regenerator and friction brake torque distribution control
strategy for a hybrid electric vehicle. Referring to Figure 1, a hybrid powertrain system
10 is illustrated for a motor vehicle 8. The hybrid powertrain system 10 includes a heat
engine 14 operating on a hydrocarbon based or fossil fuel; a clutch mechanism 16 and
a transmission 18. Transmission 18 connects to engine 14 through clutch 16 and
transmits engine rotation and power at various ratios to a pair of drive wheels 26 of the
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