Study On Open Circuit Fault Diagnosis And Fault-tolerant Control Of Single Switch In Dual Inverter Open-winding Drive With Common Mode Connected DC Buses

As an important way both to enhance the diversity of energy supplies and to reduce air pollution,the development of electric or hybrid electric vehicles,EVs or HEVs,is getting more attention.Electric drive,as the core of the powertrain system,plays an important role in vehicle'sperformance and reliability.Compared with the single inverter drive,the dual-inverter open-end winding configuration is a more ideal drive topology for new energy vehicles,particularly those powered with multi sources,considering its merits of not only better operation performance,but also greater capability in switch fault tolerance.This article uses an open-end winding drive topology with common mode connected DC buses is a novel type of topology,integrating some merits of both the separated DC-bus configuration and the single DC-bus configuration.The DC buses of the two sub-inverters are separated,allowing two different DC sources or energy storage elements being integrated directly.Meanwhile,the middle-points of the two DC buses are connected together,providing a common reference point for the two sub-inverters.As a result,the ripple voltages between the two DC buses are avoided,otherwise some negative effects would be produced.Moreover,the existence of the zero-sequence path also enhances the degree of freedom of control during fault-tolerant operation.However,that results in difficulty in fault diagnosis.Referring to this open-end winding drive with common mode connected DC buses,a single-switch open circuit fault diagnosis technique and corresponding fault-tolerant control strategy are proposed.The specific work is as follows:1)Based on the mathematical model of the open-winding induction motor,the control scheme emphasizing on the zero-sequence control as well as the neutral point voltage control are designed and verified by simulation in this paper.2)Aiming at the problem that it is difficult to accurately diagnose and diagnose the single-switch with open circuit failure,and based on the summarization of the existing reported fault diagnosis methods and fault-tolerant control methods,this paper proposes and studies the open circuit fault diagnosis methods of the single switch based on the analysis of the current characteristics of the restricted unipolar operation mode.Therefore,based on software algorithm,the accurate diagnosis of the faulty switch is realized without additional hardware detection circuit.3)Referring to the fault-tolerant operation after a single-switch open circuit faultof this open-end winding drive with common mode connected DC buses,a fault-tolerant control strategy based on the reconstruction of the switches is realized.4)Based on the simulation and experiment platform of the electric drive system of OWEIM,the proposed fault diagnosis method and fault diagnosis method are verified.