Comparison of DC capacitor requirements for 3- and 5-phase permanent magnet generators feeding diode rectifiers

This paper demonstrates the advantages of utilising 5-phase permanent magnet generator technology in diode rectifier applications by comparing with the traditional 3-phase systems. The key outcomes are that the size of the capacitor, hence volume and cost, is significantly reduced when compared with the 3-phase system. However, investigations have also been undertaken under fault scenarios. It is shown that if operation is required under open-circuit faults, the advantages of the 5-phase system in terms of capacitor size are eroded, and that special care has to be taken in sizing the capacitor to deal with the increased rms current. Experimental results are provided.