Variable Flux Direct Torque Control Of Synchronous Reluctance Motor With High Reliability And Low Vibration

The reliability and low vibration of electrical equipment,as the main performance indicators of ships,have an important impact on the safety of ships.At present,the asynchronous motor is the main motor equipment used in ships.However,the existence of rotor winding of asynchronous motor makes the motor parameters are easily affected by the environment,which makes the control accuracy low and the vibration large in operation,which poses a serious threat to the reliability of ships.Therefore,the asynchronous motor can not meet the higher and higher requirements of low vibration performance for ships,so we can consider using other high-performance motors to replace the asynchronous motor for ships.At present,permanent magnet synchronous motor(PMSM),switched reluctance motor(SRM)and synchronous reluctance motor(SynRM)are widely used in industry.PMSM has low vibration.However,for the special working conditions of ship equipment,the risk of rotor demagnetization exists;SRM and SynRM,which have no permanent magnet rotor,can adapt to complex working conditions.However,SRM has high vibration during operation,which does not meet the requirements of low vibration performance;SynRM has high PFC,its rotor has no ferrite,has strong robustness,and is more suitable for complex working conditions.Compared with switched reluctance motor,its vibration during operation is smaller,so the SynRM has a great application prospect in submarine.At present,vector control(FOC)and direct torque control(DTC)are the main driving schemes for SynRM.The DTC algorithm has a simple control structure,and the DTC scheme is compatible with the high torque response performance of the synchronous reluctance motor.At present,this method has been applied in industry,but there is no strict regulation on its vibration performance index,so it needs further research on its vibration performance when it is applied to ships.After the stator flux amplitude is given in the traditional DTC method,it will remain unchanged during the whole operation period.The given flux amplitude will lead to the decrease of control performance,larger torque ripple,and larger speed vibration.In steady-state operation,in order to keep the flux amplitude constant,the reactive power component will increase,resulting in a lower PFC of the system.In this dissertation,the problem of stator flux amplitude given in direct torque control is analyzed.Firstly,the mathematical models of SynRM in different coordinate systems are reduction,and the traditional DTC algorithm is introduced and analyzes the problems of high vibration and low PFC when the stator flux amplitude remains constant.In order to improve the PFC of the system and reduce the torque ripple and speed vibration,two schemes of variable flux direct torque control based on PFC angle(PFA-DTC)and variable flux direct torque control based on optimal flux angle(OFLA-DTC)are proposed respectively.The principle block diagrams of the traditional DTC system and the two proposed variable flux DTC systems are constructed respectively for the synchronous reluctance motor.Secondly,in order to verify the effectiveness and correctness of the proposed algorithm,the simulation models of the two methods are built-in MATLAB Simulink environment,and the start-up and anti-disturbance performance of the conventional and the improved methods are simulated and compared.According to the simulation results,compared with conventional DTC,PFA-DTC has less torque and speed vibration in steady state,especially in no-load condition;OFLA-DTC has less torque and speed vibration in steady state than traditional DTC.Compared with traditional DTC,the two methods have higher PFC.In the simulation of sudden loading and unloading,compared with traditional DTC,PFA-DTC and OFLA-DTC have larger speed drop,but their recovery time is basically the same as traditional DTC.Therefore,the proposed variable flux direct torque control system has good static and dynamic performance.Finally,in order to verify the correctness of the theoretical method and simulation results,the corresponding experimental test platform is established.Based on CCS software,the variable flux direct torque control of synchronous reluctance motor is programmed and debugged.There are mainly algorithm programs such as variable flux direct torque control,PI adjustment,current sampling and overcurrent protection.The start-up,steady-state performance,and anti-interference performance of the motor are tested on the built test platform.The experimental results show the steady-state speed fluctuation and rotation of the variable flux direct torque control system of the synchronous reluctance motor proposed in this dissertation.The moment pulsation has been reduced,and the PFC has also been improved,which proves the reliability and superiority of the method proposed in this dissertation.