A 15% reduction in fuel consumption was achieved by Deutsche Bahn’s VT642 test DMU when MTU (a leading provider of diesel engines and complete drive systems) undertook trials with a hybrid version of its Power Pack.
MTU’s Power Packs combine a DMU engine with electric, mechanical or hydraulic transmission, after-treatment, auxiliaries and cooling systems— in a single unit mounted on a support frame.
The hybrid version adds an electric propulsion module with battery, power electronics and a control system. More than 6,000 conventional Power Packs have been delivered, and MTU hopes that the hybrid version can also achieve a firm foothold in the market.
Trial runs totalling 2,300km were undertaken between January and March on the 26km Staudenbahn in Bayern. MTU used the tests to verify 70 scenarios which it had previously simulated in order to determine how the hybrid system would respond to different conditions, and how the DMU could be operated most efficiently.
MTU believes that further fuel savings would be possible on routes that are more favourable for regenerative braking. Hybrid Power Packs could also be combined with overhead electrification to produce an electro-diesel hybrid.
The trials also showed that the noise from a moving train could be reduced by 5dB, while the noise of a stationary DMU was 21dB lower, because the engine was switched off and the auxiliary systems were powered by the batteries.
Dr Ingo Wintruff, vice-president (propulsion and power generation) at MTU, said: “These test runs represent a milestone in this project as a whole. A fuel saving of 15% is a fantastic result; it means that savings of 20-25% should be possible under optimum conditions.”