Managing multiple and varying energy demands by means of energy storage in combatants with integrated electric propulsion

The potential problems of managing the power flow of pulsing energy loads together with the more conventional energy loads is a challenge that needs to be addressed if the integrated electric propulsion (IEP) concept is to advance significantly. For the all electric ship concept the primary source of energy are the main electricity generators. These feed four main types of loads: Mission essential loads needing to be available all the time, like radar: Mission important loads that must be kept working but can withstand a temporary power reduction, like the main propulsion drives: Non essential loads that can be discontinued as required, like heating; New technology loads that require pulses of energy on a irregular basis that must be provided exactly when the demand occurs. The short-term demands for electrical energy of the combined loads can significantly exceed the available energy from the main electricity generators. In such cases a set of suitable intermediate energy store are required, together with an integrated power management system that co-ordinates all the energy flows to meet the defined performance levels. There are several potential sources of stored energy in a combatant; these include the combatant's linear kinetic energy, the rotational energy of the main propulsion drive as well as any dedicated energy stores. The paper describes how these energy stores can be used to meet the defined performance levels. In particular the requirement for an aircraft launch system in future all electric aircraft carriers has led to an interest in electromagnetic launch systems to replace the steam catapult. The design features of an electromagnetic launch system are described together with the options that makes it compatible with an integrated power management system.