Dual-Mode and New Diesel Locomotive Developments

Abstract

The integration of electric and diesel traction into a single rail vehicle is technically challenging because of weight and space restrictions, particularly for AC catenary power. Through the combination of recent developments in power converter technology, diesel engine design, and mechanical lightweight structures, dual-mode locomotives are now feasible for railroad applications. Apart from the different modes of traction, such locomotives must also fulfill the latest vehicle standards in regard to safety, environmental impact, and interoperability. A key component is the DC link of the traction converter, which interfaces to electric and diesel power supply systems. In addition, batteries, supercaps, or both can be interfaced to this DC link. All electric power flow is bidirectional and thus permits many possibilities for energy savings and reductions in exhaust emissions. The performance of a dual-mode locomotive is greatly enhanced by the latest high-speed diesel engines developed for off-road and industrial applications. Not only do the engines provide high diesel power at low weight, but they also meet the new Tier 3 and upcoming Tier 4 exhaust emission standards. For maximum vehicle performance in both modes, the car body and truck must be lightweight. A monocoque car body and fabricated truck are the obvious solutions, as used on the dual-powered ALP-45DP and the European TRAXX AC3, which is an electric locomotive with a diesel engine for operation on nonelectrified sidings and terminals. The above technologies also lend themselves to new diesel–electric locomotives, by yielding a high vehicle performance at low axle loads, as required for passenger services at 125 mph.