Method of and apparatus for controlling charging and/or discharging of a battery for a hybrid electric vehicle

#1. Field of the Invention

#The present invention relates generally to a hybrid electric vehicle (HEV), and specifically to a method and an apparatus for controlling charging and/or discharging of a HEV battery.

#2. Discussion of the Prior Art

#Other objects of the present invention will become more apparent to persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying figures.

#The foregoing objects, advantages, and features, as well as other objects and advantages, will become apparent with reference to the description and figures below, in which like numerals represent like elements and in which:

#FIG. 1 illustrates a general hybrid electric vehicle (HEV) configuration.

#The present invention relates to electric vehicles and, more particularly, hybrid electric vehicles (HEVs). FIG. 1 demonstrates just one possible configuration, specifically a parallel/series hybrid electric vehicle (powersplit) configuration using an Internal Combustion Engine (ICE).

#In a basic HEV, a planetary gear set 20 mechanically couples a carrier gear 22 to an engine 24 via a one-way clutch 26. The planetary gear set 20 also mechanically couples a sun gear 28 to a generator motor 30 and a ring (output) gear 32. The generator motor 30 also mechanically links to a generator brake 34 and is electrically linked to a battery 36. A traction motor 38 is mechanically coupled to the ring gear 32 of the planetary gear set 20 via a second gear set 40 and is electrically linked to the battery 36. The ring gear 32 of the planetary gear set 20 and the traction motor 38 are mechanically coupled to drive wheels 42 via an output shaft 44.

#The planetary gear set 20, splits the engine 24 output energy into a series path from the engine 24 to the generator motor 30 and a parallel path from the engine 24 to the drive wheels 42. Engine 24 speed can be controlled by varying the split to the series path while maintaining the mechanical connection through the parallel path. The traction motor 38 augments the engine 24 power to the drive wheels 42 on the parallel path through the second gear set 40. The traction motor 38 also provides the opportunity to use energy directly from the series path, essentially running off power created by the generator motor 30. This reduces losses associated with converting energy into and out of chemical energy in the battery 36 and allows all engine 24 energy, minus conversion losses, to reach the drive wheels 42.