Research On Drive And Fault-tolerant Control Strategy Of Five-phase Permanent Magnet Synchronous Motor

With the rapid development of science and technology,motor drive control system as an important link in modern industrial production,has been widely concerned and studied by scholars at home and abroad.Multi-phase permanent magnet synchronous motor has broad application prospects in the field of high reliability requirements because of its advantages such as low torque ripple,high power density,high efficiency and strong fault tolerance.With the continuous development of modern control theory and the rapid development of power electronics technology,the motor drive system has been separated from the traditional three-phase power supply network.Due to the increase of the number of stator windings,the control freedom of the drive system has increased,and the design flexibility has been improved accordingly.The failure of the multi-phase motor drive system makes the system unstable and threatens the industrial production.Therefore,it is very important to study the fault-tolerant control strategy after the failure.Therefore,taking the five-phase permanent magnet synchronous motor as the research object,this paper studies the control strategy of normal operation and fault-tolerant operation of its drive system.Firstly,the multi-phase motor and its control strategy,as well as the development and overview of multi-phase motor fault-tolerant control technology are summarized and described,so as to determine that this paper analyzes and studies the five-phase permanent magnet synchronous motor drive system.The mathematical model of five-phase permanent magnet synchronous motor in natural coordinate system is established,and the mathematical model in rotating coordinate system is established according to the coordinate transformation matrix under the expanded five-phase motor system.The drive control block diagram of fivephase permanent magnet synchronous motor is built,and the vector control strategy based on space vector pulse width modulation technology is adopted when the five-phase permanent magnet synchronous motor is in normal operation;The space voltage vector under the topology of five-phase voltage source inverter is studied and analyzed.In order to reduce the harmonic content of the motor and make the motor run more stable,the adjacent four vector space vector pulse width modulation method is used to realize its vector control strategy.Secondly,based on the principle that the magnetomotive force remains unchanged before and after motor fault,the fault-tolerant current expression after single-phase open circuit fault of five-phase permanent magnet synchronous motor is calculated,and then the space voltage vector expression reconstructed after single-phase open circuit fault can be obtained through the position relationship of residual phase space vector,so as to realize the synthesis of target vector,and then realize the fault-tolerant control strategy after single-phase open circuit fault based on space vector pulse width modulation technology.Finally,in order to realize the smooth conversion of electromechanical energy in the motor drive system,the reduced order transformation matrix of five-phase permanent magnet synchronous motor in the case of adjacent two-phase open circuit fault is constructed,the space voltage vector is reconstructed according to the reduced order transformation matrix,and the space vector pulse width modulation technology is used to realize the fault-tolerant control after two-phase open circuit fault,compared with the traditional current hysteresis tracking pulse width modulation control mode,the fault-tolerant control strategy based on space vector pulse width modulation technology is more superior.