Rsearche On Direct Torque Control Strategy Of Dual Three-phase Synchronous Reluctance

At present,my country is advancing in an orderly manner to achieve carbon peaking and carbon neutrality.The report of the 20 th National Congress of the Communist Party of China also mentioned that the construction of the future energy system should be established first and then broken,and vigorously develop new energy sources.However,the inherent randomness,volatility,and intermittent characteristics of new energy determine the need for highly reliable and high-power energy storage equipment as supporting equipment for the large-scale application and promotion of new energy.Flywheel batteries have the advantages of strong environmental friendliness,long life,high specific power,and high cycle efficiency,and are ideal physical energy storage methods.The motor in a flywheel battery has a critical impact on its performance,and the dual three-phase synchronous reluctance motor(Syn RM)due to its simple structure,low cost,small torque ripple,high reliability,and almost no occurrence of self-discharge and other characteristics,especially suitable for application in flywheel batteries.In this thesis,the dual three-phase synchronous reluctance motor is selected as the research object,and the research is carried out in the following aspects:(1)On the basis of analyzing the winding magnetomotive force of multi-phase motor,the frequency of torque ripple of double-three-phase motor is analyzed,and the principle of reducing torque ripple of double-three-phase motor is expounded.Based on the vector space decoupling method,the mathematical model of dual three-phase Syn RM is established,and the distribution law of the space voltage vector of dual three-phase Syn RM in the fundamental and harmonic subspaces is studied after vector space decoupling.The traditional direct torque control(DTC)based on large vector is applied to the dual three-phase Syn RM,and the reason why this method cannot suppress the 5th and 7th current harmonics is analyzed.(2)Analyze the influence of the winding structure of the dual three-phase Syn RM on the harmonic magnetomotive force,and reveal the mechanism of the generation of the 5th and 7th current harmonics during the operation of the dual three-phase Syn RM.Study the principle of SVPWM algorithm to suppress harmonics and its shortcomings.By analyzing the corresponding relationship between the 12 large vectors in the fundamental subspace and the 12 small vectors in the harmonic subspace,the method of synthesizing the low harmonic control vector with three adjacent large vectors is found.Replace the large vector in the switch table with the low harmonic vector,and design the harmonic suppression switch table.The torque response speed and switching frequency of the low harmonic vector are improved and optimized for the large vector calling sequence in one control cycle.(3)The fault-tolerant control strategy based on dimensionality reduction coordinate transformation after a phase loss fault is studied.Although this method is better than the previous fault-tolerant control strategy,it is still based on discarding the faulty phase winding.The voltage vector distribution of dual three-phase Syn RM after one-phase fault is analyzed,and the space voltage vector distribution after connecting the fault phase and the non-fault phase is compared.Study the fault-tolerant control strategy of dual-three-phase Syn RM driven by five bridge arms,and use the fault-tolerant control vector to replace the large vector,which can not only achieve fault-tolerant operation but also suppress harmonics,and the faulty phase winding of the motor can continue to operate.(4)The dual three-phase Syn RM drive system experimental platform is built with the RTU-BOX digital controller as the core,and the effectiveness of the harmonic suppression control strategy of synthesizing low harmonic vectors is verified by using this platform.