A Survey Study on ePump Design Architectures for Mobile Hydraulics

Abstract With the electrification trends affecting mobile hydraulics, there is a growing need for energy-efficient and compact hydraulic supply units driven by electric machines, also known as ePumps. This paper aims to compare various ePump designs that utilize different combinations of “best-in-class” commercially available hydraulic pumps and electric machines (EMs), to meet the requirements of a generic mobile hydraulic application. The paper intends to discuss the effect of the design architecture of the combination of a permanent magnet synchronous machine (PMSM), with several hydraulic pumps, including axial piston machines, bent axis piston machines, external gear machines, vane pumps, and radial piston pumps. A large combination of ePump architectures exists, and for engineers, it can be challenging to assess the pros and cons of each option for an electrified application. To address this challenge, in this paper, different commercially available pumps and an EM are chosen to evaluate key performance and design parameters such as drive cycle efficiencies, mass, and volume. Qualitative cost and power density considerations are also investigated. The effect of variable displacement ePump operation on the drive cycle is demonstrated for two ePump cases. By providing a benchmarking based on a generalized utilization cycle, this study serves as a guideline for selecting appropriate ePump architectures in electrified mobile hydraulic applications.