Research On High Performance Speed Control And Fault Tolerant Operation Of The Dual Three-Phase PMSM

Motor drive system is the important power foundation to support the national economic development and national defense construction,and high-performance motor drive system has become one of the core elements of equipment manufacturing industry to develop toward high-end direction,especially according to the "Made in China 2025" manufacturing strategy for the top ten industries with competitive advantages and strategic industries deployment,higher quality of the motor system operational performance is required.The demands include high power density,high reliability,high adaptability,high precision,low emission and multifunction(4H+1L+1M).Meanwhile with the rapid development of the modern power electronics technology and the microelectronics technology,the modern electric drive technology is no longer limited to the traditional three-phase AC drive system;compared with the traditional three-phase AC drive system,multi-phase motor drive system can use low-voltage devices to achieve high-power drive,with a more stable torque output,and better fault-tolerant operation capability and other characteristics.It has better competitive advantage in the aerospace,ship drive,electric vehicles,wind power generation and other high-reliability high-power drive occasions.In this dissertation performance of the motor drive system with high precision and high reliability is chosen as the research target,and dual three-phase permanent magnet synchronous motor which has two sets of three-phase windings phase shifted by 30 electrical degrees is chosen as research object.Its mathematical modeling,PWM modulation,the influence on the system caused by the deviation of the rotor angular detection,hybrid FOC-u/f control,and fault tolerant control strategy under the case of one phase open circuit and other theories are deeply analyzed,and the proposed methods are verified by experiments.Firstly,the mathematical modeling of the dual three-phase permanent magnet synchronous motor in the harmonic basis vector space decomposition and the double dq rotation coordinate system are analyzed.Because there is an inductive coupling relationship between the di-d2 axis and the qi-q2 axis in the double dq rotating coordinate system of the dual three-phase permanent magnet synchronous motor,the all decoupling mathematical model in the D-Q-Do-Qo coordinates is established by the decoupling transformation eliminating the influence of the coupling inductance.Then the three mathematical models are compared,and the intrinsic mechanism of each subspace corresponding to the model is analyzed.Based on that to realize vector control PWM,the 64-voltage space vector of ?-? and z1-z2 under harmonic basis is synthesized equivalently by dual SVPWM voltage space vectors with phase shifted by 30 degrees.Secondly,aiming at the influence on the drive system caused by the deviation of the rotor position angular detection,the dynamic mathematical models of the permanent magnet synchronous motor with angular deviation of the rotor detection is established,and the influence of the angular deviation of the rotor position detection on the performance of the drive system is analyzed relatively comprehensively.And the influence of the rotor angle detection deviation on the horocycle of voltage and current,the steady-state performance such as the efficiency of the motor,current steady-state value,the influence of the copper loss and the stable running interval are analyzed,and the influence on the dynamic properties such as torque response ability is analyzed.According to different drive performance requirements,the conclusion provides a reference for the angle observation accuracy of PMSM,and the design of position sensorless controller and the selection of position sensor are clarified.Thirdly,hybrid FOC-u/f control strategy for dual three-phase PMSM is presented according to the characteristics of open loop u/f control and field oriented control of PMSM,which fuse high performance dynamic speed regulation characteristic of field oriented control and high steady-state speed control precision characteristic of open loop u/f control effectively.The selection of load torque angle and the dynamic regulation ability under small disturbance are analyzed.The dynamic speed regulation performance and steady-state speed control precision of the dual three-phase permanent magnet synchronous motor are promoted effectively.In order to reduce the transient impact in the switching process,the switching criterion and switching method between the two modes are given,and the smooth transition between the two control modes is realized.The validity of the control strategy is verified on the experimental platform.Lastly,in consideration of one phase open circuit failure which is common in dual three-phase permanent magnet synchronous motor,a fusion fault-tolerant control strategy for dual three-phase permanent magnet synchronous motor under neutral isolation is presented in this dissertation.The remaining five-phase windings are equivalent to the symmetrical three-phase permanent magnet synchronous motor and single-phase permanent magnetic synchronous motor after one phase open circuit failure,and the dynamic mathematical models are established under synchronous rotating d-q coordinate system and natural coordinate system respectively.According to the characteristics of the electromagnetic torque of the two sets of windings after the fault,the different distribution modes of motor output torque between two sets of windings are analyzed,and the torque distribution factor k is defined.It is pointed out that the existing single three-phase fault-tolerant control mode is a special operating mode when the torque distribution factor k=0.In order to utilize the windings of single-phase permanent magnet synchronous motor effectively,the remaining five phase current-sharing fault-tolerant control mode and the remaining five phase smooth torque fault-tolerant control mode are adopted to meet the requirements of more load conditions.The optimal selection of three fault-tolerant modes under different load conditions,the theoretical analysis of control strategy and switching process,and the design of software and hardware are completed.Experiment results show that the fusion fault-tolerant control strategy can effectively fuse the advantages of the three kinds of fault-tolerant control modes,with high hardware and software compatibility,and the switching process is reliable,and the performance of the system can be effectively improved,meanwhile improve the reliability of the system further.