Research On Temperature Monitoring And Active Control Of Dual Three-phase Permanent Magnet Synchronous Motor

The internal temperature of motor is an important factor affecting the safe operation.Excessive temperature will not only shorten the life of motor,but also increase the possibility of motor failure.This paper takes the dual three-phase permanent magnet synchronous motor(PMSM)as the research object,to study the motor temperature monitoring and active control methods.By constructing the loss model and thermal field model of the system,the temperature of motor under normal and fault conditions is monitored online,and the active temperature management is implemented under different working conditions to improve the reliability of motor operation.The paper firstly establishes the mathematical model of the dual three-phase PMSM in the natural coordinate system,the dual synchronous coordinate system,and the vector space decoupling transformation.And the dual three-phase motor control strategy in different coordinate systems are designed.Then,the loss model of dual three-phase PMSM considering the influence of frequency and magnetic flux density is established,and a loss model parameter identification method based on particle swarm optimization(PSO)is proposed.The method uses the PSO with experimental data under the motor normal operation to establish the loss model,which can realize the high-precision online calculation of motor loss.In terms of motor temperature monitoring under normal conditions,a five-node thermal network model is proposed,which includes two sets of stator core and winding nodes,that can reflect the motor circumferential temperature difference.Furthermore,combined with the independent control ability of two three-phase windings and the circumferential temperature difference of motor,an active temperature management strategy for dual three-phase PMSM is proposed in this paper.Compared with the conventional three-phase motor,this method can make better use of the temperature rise space of motor,and effectively increase the maximum output of motor within the safe temperature limitation.In order to further improve the reliability of the dual three-phase PMSM,this paper studies the fault condition of motor.Inter-turn short circuit(ITSC)is one of the most common motor faults,and its local rapid temperature rise will cause strong damage effection.In this paper,the ITSC fault characteristics of the dual three-phase PMSM are analyzed in detail by establishing the mathematical model in the natural stationary coordinate system and the double synchronous coordinate system.At the same time,a calculation method of motor copper loss based on faulty phase voltage is deduced and proposed,which can accurately calculate the additional copper loss caused by short-circuit current and provide effective loss information for the temperature prediction of motor in fault state.On this basis,the paper proposes a four-node thermal network model of motor under ITSC,which can realize the online monitoring of the hot spot temperature of the fault.After comparative analysis of different short-circuit current suppression methods,this paper proposes a fault-tolerant control strategy for ITSC that combines variable permanent magnet flux technology and temperature prediction information.The method can effectively improve the operation efficiency of motor in fault state by implementing the short-circuit current suppression strategy in sections.Compared with the traditional fault-tolerant control strategy,this method can not only improve the waveform quality and reduce the torque fluctuation,but also control the temperature of motor within a safe range,prevent the fault spread caused by local high temperature,and realize the motor maximum output operation within safe temperature limits.This paper verifies the correctness of the above mathematical modeling,theoretical analysis,and control strategy through finite element analysis(FEA)simulation,Matlab/Simulink simulation and experiment.