Principle

Modern diesel-electric vehicles with 3-phase traction motors can be braked dynamically by using the electric traction motors as generators. This capacity is usually exploited in order to have a wear-free braking mode. The control of the traction system can be designed in such a way that part of the recovered energy can be used to feed on-board consumers.

Technical details

In modern diesel-electric 3-phase locomotives the Diesel engine drives a generator feeding the DC link. The DC link feeds the traction inverters as well as the auxiliaries and the train bus supply. During braking, the traction motors feed the recovered power into the DC link. This additional power can either be converted into heat in braking resistors or used for other consumers, namely auxiliaries (compressors, ventilation etc.) or the train bus supply (supplying the comfort functions in passenger trains).The power management is usually realised as follows: The recovered braking power is fed into the DC link. The part of this power that can be used for auxiliaries or train bus supply is drawn from the DC link, the rest is dissipated in the resistors. The resistor is automatically "switched on" if the voltage in the DC link exceeds a certain limit value.