Research On Fault Diagnosis And Fault Tolerant Control Algorithms Of Open Circuit Fault In Open Winding Motor Drive System

Electric vehicle(EV),as an important way to improve energy utilization,reduce environmental pollution and improve energy supply diversification,has drawn more and more attention from all countries in the world.EV is gradually replacing conventional energy vehicles as the main mode of transportation.Due to its importance of being the power core of electric vehicles,motor and its drive control system play an important role in vehicles' operation performance and reliability.The reliability of motor drive system is particularly prominent due to the special application occasions and application requirements of electric vehicles.Early reports showed that about 38% of converter system failures in industrial frequency conversion applications were caused by the failure of switching devices.With the improvement of power electronic technology,its failure ratio has decreased,but 31% of failure rate still makes it the most vulnerable device in the converter system.For electric vehicles,the failure of electric drive system will not only cause safety accidents,but also increase the cost of operation and maintenance.Aiming at the current demand of electric drive system for new energy vehicles and its application characteristics.This paper will focus on the open-winding induction motor system(OEM-IM)driven by dual inverters.The specific research contents can be summarized as follows.Firstly,an open circuit fault diagnosis scheme for single switch in OEW-IM system is designed.The diagnostic variable is constructed by using the average value of three-phase current and the standard unitary average value of the system.By using this diagnostic variables,we can judge whether the system switch is open or not,and locate the fault phase.Furthermore,we can lock the fault switch range to a switch alignment.a unipolar switch fault identification scheme is designed.Put it specifically,when the fault switch alignment is confirmed,Block the driving signal of the Non-Fault switch from the faulty phase,then change the duty cycle of its complementary switch,so as to make the phase current convenient for us to extract fault information and know the accurate location of fault switch.Secondly,A fault-tolerant control scheme based on instantaneous active power of open-winding motor is designed.When the fault of one single switch is detected,we block the driving signal of other switches in the faulty phase,then carry out the instantaneous active power optimization strategy,generates the current references necessary for the remaining phases to supply the required power,thus eliminating electromagnetic torque ripple of OEW-IM system,simultaneously minimizing the copper loss of stator.At last,based on matlab simulation and system experiment platform,the stability and accuracy of the diagnosis scheme are proved.While in the matlab simulation software environment,the validity and superiority of fault-tolerant control method are verified.