Patent ID: 8261860

Claim:
Hybrid powertrain system, comprising: an electrical energy storage device; an electrically-powered torque machine configured to generate torque transferable to a driveline and react torque from the driveline; a plurality of reciprocating free-piston internal combustion engines each including a linear alternator device configured to generate electric power when in an engine-on state, each reciprocating free-piston internal combustion engine configured to generate a rated output power differing from rated output powers of the other reciprocating free-piston internal combustion engines when operating at resonant speeds; a power electronics circuit configured to transfer electric power between each of the linear alternator devices, the electrical energy storage device and the torque machine; and a control module configured to determine mechanical and electrical power demands responsive to an operator torque request and a state of charge of the electrical energy storage device, command operation of the torque machine to generate an output torque responsive to the mechanical power demands, and command operations of the reciprocating free-piston internal combustion engines to generate electric power responsive to the electrical power demands.