Research On Fault Tolerance Method For Inter Turn Short Circuit Fault Of Axial Permanent Magnet Synchronous Motor With In Phase Coil Compensation

The appearance of PMSM and its control system improves the safety and reliability of motor control system.It has strong fault tolerance due to its characteristics of thermal isolation,magnetic isolation,physical isolation,electrical isolation and large inductance,so it has been widely used in many fields.However,the existing PMSM adopts a large winding inductance to suppress the short circuit current caused by the short circuit between turns,and also brings the defect of low power density under normal working conditions.In addition,for the short circuit with less turn,especially the one turn fault,the existing permanent magnet synchronous fault-tolerant motor still produces the over amplitude short circuit current,and the fault tolerance effect is not good.This paper presents a new type of special motor,which is different from the traditional permanent magnet synchronous fault-tolerant motor stator structure and winding connection mode,which is called the phase coil compensated axial permanent magnet synchronous fault-tolerant motor.The motor has the quasi automatic fault tolerance capability of inter turn short circuit fault,that is,it can automatically realize fault-tolerant operation without control strategy in most turn to turn short circuit faults.Only in case of short circuit fault(short-circuit turn number is very few),the short-circuit current should be restrained by control strategy.This paper focuses on the fault tolerance characteristics of the interturn short circuit,and makes a thorough and detailed theoretical and Simulation Analysis on the working characteristics,fault tolerance theory,on-line fault detection method and short circuit current suppression measures.The specific research contents include the following points:1.the synchronous fault-tolerant motor with the same phase coil compensation is proposed.The magnetic field distribution of the special motor under normal working condition and turn to turn short circuit fault state is studied by using magnetic circuit analysis method.The fault-tolerant operation mechanism is analyzed in depth,and compared with the traditional permanent magnet fault-tolerant motor.On this basis,the mathematical model of the special motor under normal operation condition and interturn short circuit fault condition is established.2.the operation characteristics of the three-dimensional prototype model are studied by Ansoft finite element simulation software.The dynamic characteristics of the special motor under the condition of sudden turn to turn short circuit are studied.The transient and steady state characteristics of the stator winding phase current and short circuit current under different turn to turn short circuit conditions are analyzed.3.based on the special motor’s unique shunt magnetic leakage circuit of stator yoke,the influence of short circuit current on the electrical parameters of each phase winding after the turn to turn short circuit fault is deduced.An online detection method for the position of interturn short circuit fault is proposed.4.after the fault position is detected online,a method of suppressing short circuit current by injecting demagnetizing current is proposed,which is suitable for the special motor.The suppression effect of the method to different coil short-circuit current is analyzed by simulation.