Research On The Detection And Control Technology Of Open-phase Fault Of Pmsm

Permanent magnet synchronous motor(PMSM)is widely used in many fields because of its high power density,high efficiency and low energy consumption.However,due to the working principle and working environment of PMSM,the reliability of motor drive system is reduced.One of the most common faults in the motor drive system is the open-phase fault,which is often caused by the disconnection of one phase of the motor,the disconnection of one phase of the inverter or the poor contact of the mechanical terminals.In the case of open-phase fault,the performance and efficiency of the motor will be reduced due to the imbalance of phase currents.Especially in extreme cases,it may cause irrecoverable damage to the motor drive system.Therefore,the fault diagnosis and fault-tolerant control technology of open-phase fault become particularly important to ensure the reliability of the control system.This paper mainly analyzes and studies from the mathematical modeling of the motor system,the detection of the open-phase fault of the motor,the fault-tolerant control of the open-phase fault of the motor and the fault-tolerant control of the open-phase fault of the inverter.Following are the main contents of this paper:1.This paper focus on the basic structure and mathematical model of PMSM,through the comparative analysis of three commonly used coordinate transformation,establishes the mathematical model of PMSM in these three different coordinate systems,and establishes the mathematical model of the motor in case of fault according to the fault characteristics of the motor in case of open-phase fault.2.To detect the open-phase fault of PMSM,using the least squares algorithm based on forgetting factor to identify the three-phase stator resistances of the motor,according to the change of the fault phase resistances,and by setting an appropriate threshold to detect the specific fault phase.3.The fault-tolerant control is performed for one-phase open-circuit fault of one phase winding of PMSM,and the three-phase four-switch fault-tolerant topology is adopted to ensure that the motor can continue to operate after fault.Firstly,this paper establishes a mathematical model of the motor when using a three-phase four-switch fault-tolerant structure,analyzes and verifies the impact of this fault-tolerant topology on the motor drive system,andthen proposes a proportional-integral quasi-resonant control strategy for the current loop to achieve the suppression of ripple in torque and speed,thereby ensuring high reliability of PMSM operation under open-phase fault.4.Aiming at the one-phase open-circuit fault of the inverter in PMSM drive system,a strategy for suppressing torque ripple of a motor fed by a three-phase four-switch inverter is proposed.When a three-phase four-switch inverter is used,the performance of the motor will be seriously affected by the voltage fluctuations of the two dc-split capacitors.Therefore,this paper first establishes a mathematical model when the motor uses a three-phase four-switch inverter,analyzes the impact of capacitor voltage fluctuations on the system,and then uses the proportional-integral quasi-resonant control strategy of the current loop to improve the current waveform,thereby suppressing the periodic ripple of motor torque and speed.