OPEN-CIRCUIT FAULT TOLERANCE OF MULTIPHASE GENERATOR RECTIFIER SYSTEMS

Generator rectifier systems are widely used in transport applications to provide a DC power source. Multiphase generators are attracting interest in the marine and aircraft sectors for medium voltage operation (above 1kV) with fault-tolerant capability. Fault tolerance is enhanced by using a split phase arrangement, where the windings are grouped into submachines, each with its own rectifier that can be interconnected in series or parallel to create the output voltage. This paper uses a 15-phase example, configurable as three 5-phase or five 3-phase submachines, to investigate fault tolerance. The results allow previous work on 12-phase machines to be generalised for any number of phases. In addition, series stacking is shown to maintain DC current whereas parallel stacking maintains the DC voltage. The removal of an entire submachine is shown to be more effective than operating with an unbalanced system due to a single open-circuit coil or diode.