Research On The High Reliability Dual-Winding Fault-Tolerant Permanent Magnet Motor And Its Control System

With the increasing development of more-electric aircraft,the requirement of the electric drive system for aerospace applications is becoming more and more high.In addition to meet some specific functions,motor drive system for aerospace applications must have high reliability and strong fault tolerance.Hence,the fault-tolerant permanent-magnet(PM)motor drive systems have attracted more and more attentions.For improving the drawbacks of the traditional fault-tolerant PM motor drive systems and their control strategies,this thesis researches the dual-winding fault-tolerant permanent magnet(DFPM)motor drive system and its fault-tolerant control strategy.This thesis mainly includes the following contents:To improve the performance of the traditional fault-tolerant PM motor drive systems,a novel electric drive system based on the DFPM motor for aerospace applications is investigated.According to the design requirements of an aircraft electric drive system,this thesis researches the optimization design,fault operation analysis,finite element analysis and prototype experiment validation of the DFPM motor.The DFPM motor has the advantages of magnetic isolation,physics isolation,thermal isolation,small cogging torque ripple,inhibiting the short circuit current and high fault tolerance.Compared with the traditional fault-tolerant PM motor drive systems,the DFPM motor drive system needs the number of power switches and independent power supply is least,over kVA/kW ratio is largest.The DFPM motor drive system is a most suitable fault-tolerant motor drive system for aerospace applications.The traditional fault-tolerant control strategy is too complex and its switching frequency is not fixed lead to have a big current ripple.The active-active redundant fault-tolerant control strategy of the DFPM motor drive system based on vector control is proposed and investigated.The system mathematical model,redundant fault-tolerant control principle,open-circuit fault diagnosis and processing strategy,short-circuit fault diagnosis and processing strategy,and redundancy communication strategies are analyzed and introduced.Then,the operational performance of the drive system under open-circuit and short-circuit fault have been verified by simulation and experiment.The proposed redundant fault-tolerant control strategy is simple and has the functions of fault diagnosis and redundant communication between the two redundancies.Each redundancy provides smooth torque,in general,loss of one redundancy does not bring in ripple or drag torque into the drive system.The research results show good fault-tolerant characteristic of the DFPM motor drive system,namely,the output performance of the DFPM motor drive system under open-circuit and short-circuit fault conditions is almost the same as normal condition,which verified the proposed redundant fault-tolerant control strategy.To achieve the four-quadrant fault-tolerant operation for the helicopter winch applications,the four-quadrant fault-tolerant operation control strategy is proposed.Then,the electromagnetic performances of the DFPM motor drive with open-circuit and short-circuit fault under the four-quadrant operational condition have been verified by experiments.Experimental results are presented,showing the effectiveness of the proposed four-quadrant fault-tolerant operation control strategy.The common open-circuit fault diagnostics have the issue of false alarms when load change suddenly or speed change suddenly.A new strong robustness open circuit fault diagnosis strategy of the DFPM motor drive system is proposed and investigated.The simulation and experimental results show that the proposed strong robustness open circuit fault diagnosis strategy can overcome the issue of false alarms when load change suddenly or speed change suddenly and it can overcome the issue of false alarms under the no-load or light-load conditions.The proposed strong robustness open-circuit fault diagnostic strategy can realize real-time detection and localization of single power switch or one phase winding open-circuit fault.In order to adapt to the single power supply system of the aircraft,a novel DFPM motor drive system and fault-tolerant control strategy based on the redundancy bridge arm are proposed and investigated.To achieve the fault diagnosis performance of the drive system,the diagnosis and processing methods of the open-circuit fault and the short-circuit fault have been proposed and investigated.The operational performance of the drive system under open-circuit and short-circuit fault have been verified by simulation and experiment.The research results verify the reliability and effectiveness of the proposed the DFPM motor drive system and fault-tolerant control strategy based on the redundancy bridge arm.The proposed DFPM motor drive system based on the redundancy bridge arm can not only adapt to the single power supply system of the aircraft,reduce the number of power switches and independent power supply,save the electric drive system cost,but also improve power density,the reliability and the utilization rate of the electric drive system.At the same time,the drive system has stronger fault-tolerant ability and it can realize the fault tolerant control for one phase winding fault or multiphase winding fault.