Regenerative Drive for Subway Trains—Part 3: System Evaluation

Abstract

The most efficient hybrid drive philosophy eliminates high-acceleration power peaking and operates as a fully regenerative system (little or no accumulator top-off during station stop). The optimal accumulator control concept is designed as vehicle velocity dependent and is shown to vary only slightly with vehicle load and station distance. Furthermore, accumulator sizing is numerically determined subject to this control concept. The effect of large coast (5 percent) or cruise periods opposes the justification of any regenerative system and is herein questioned as an integral part of the drive cycle. Conversely, short coast (2 percent) or cruise has little effect on the hybrid drive performance. As a basis of comparison (with other drive systems), the ideal vehicle concept is postulated.