Dual wound machines for electric ship power systems

Electric Ship Power Systems, with integrated ship service and propulsion segments, offer significant advantages to warship designers and particularly so in the context of high and directed energy weapon systems. Practical considerations lead to a mix of prime mover and generator sizes being used but straightforward inter-connection between them leaves each subsystem vulnerable to influences imposed by the other. The concept of tandem generators - either separate electrical machines, or tandem electrical machines in one frame - driven from one prime mover, attempts to square this circle by providing galvanic isolation between the two sub-systems whilst still feeding each from common prime movers. But the two machines are difficult to integrate closely, especially if both use optimal lengths and diameters. One solution is to use a dual wound machine whereby the windings of the two separate generators share the same slots. This paper considers such a dual wound machine from the perspective of its air gap flux density and considers how much electro-magnetic isolation between the two circuits will exist.