Research On Fault Operation Mode Of Rectifier Bridge Of 12-phase Rectification Synchronous Generator System

12-phase synchronous generator with rectifier-load systems are widely used in ships owning to its advantages of high DC power supply quality and good fault-tolerant performance. To study the performance of the system in fault operation, a simulation model of the 12-phase synchronous generator with rectifier-load system was established based on circuit topology theory. With the first 25 harmonic components of the field MMFs taken into consideration, the model is simplified and more accurate. Loop-current topology-varying network equations of the system were established and numerically solved in fast simulate speed.A novel numerical method based on the magnetic vector potential is proposed to calculate stator end leakage inductances of the multiphase induction machine with the conic angle of end-windings taken into consideration. To acquire the leakage inductances between end-windings, the flux is obtained by a line integral of vector-potential along the end-winding sides. The new method is of more accuracy and higher computation speed, and makes it easy to deal with the complicated end-winding frameworks. By following the general procedure which according the incidence matrix to obtain the phase end leakage inductances, the new method retains advantages of flexibility and versatility.To study the bridge fault performance of 12-phase synchronous generator-rectifier-load systems, a judging method of the on-off condition of diodes in fault state is proposed in this paper, taking the uncontrolled rectifier bridge as an example. The analysis method is verified correct by comparing the simulation results with the experiment data, providing the method and theoretic foundation for the fault-tolerant feasibility analysis of multi-phase rectifier generators in diode-fault operation.For four bridge-loss fault operations of the 12-phase rectifier generator systems, the asymmetric operating performance and the DC power quality were analyzed, which provide the theoretic foundation for the fault-tolerant feasibility analysis of bridge-loss operations of multi-phase rectifier generators. For the single-diode-open fault operation, the DC power supply quality and the asymmetric operating performance is also discussed with the simulation, and it can be concluded that the level of the influence on power supply quality is related to the load on the DC side. For the single-diode-short fault operation, the characteristics of voltage and current of is discussed with the simulation, providing theoretical basis for the formulation of the protection scheme.By comparing the simulation results with the experiment results of a 4 kW model machine operating in both normal mode and fault modes, the simulation model is verified to be of effective and accurate.