Modeling, Design, and Testing of a Linear Electric-Hydraulic Conversion Machine for Electrification of Off-Highway Vehicles

Electrification and hybridization of off-highway vehicles have the potential to yield significant fuel savings and air emissions improvements. However, developing the required components to electrify these systems is an extremely challenging task due to high force and power density requirements and highly variable drive cycles. This article investigates a new approach to off-highway vehicle electrification based around a linear piston pump integrated into a linear actuator. The article first reviews linear actuator machine topologies within the context of the charge pump application requirements. A tubular machine topology is optimized for integration with a hydraulic pump and experimentally validated using a prototype machine. A multiphysics simulation framework is developed to simulate the entire charge pump design with a position regulator. An optimized design is proposed with an oscillation frequency of 132 Hz and a total system efficiency (pump and motor) calculated to be 81.3% at full load.