Research On Operation Mechanism Of 30kW Six Phase Open Winding Permanent Magnet Synchronous Motor For Military Vehicle

At present,the development of high-performance rare earth permanent magnet materials,power electronic switching devices,pulse width modulation technology and motor control technology makes the permanent magnet synchronous motor develop rapidly.Permanent magnet synchronous motor has the unique advantages of high power density,high torque inertia ratio,high efficiency and flexible magnetic steel structure.It is widely used in transportation,power generation,AC servo and transmission fields.Compared with the traditional three-phase motor,the multi-phase motor has higher degree of freedom,better fault-tolerant performance,more control degrees of freedom,and flexible vector modulation combination,which meets the reliability requirements of the motor system in the vehicle environment.The combination of open winding motor and H-bridge inverter can improve the control flexibility of the motor drive system,and eliminate the defects of zero sequence subspace harmonic injection when the multi-phase motor system is fault tolerant.The research on open winding multi-phase permanent magnet synchronous motor has important theoretical significance and engineering application value.In this paper,the six phase open winding permanent magnet synchronous motor and its drive system are taken as the research object,and the key problems such as vector control theory,space vector pulse width modulation(SVPWM)strategy,fault-tolerant operation characteristics after fault are studied.The mathematical model of six phase open winding PMSM in natural coordinate system is established,the park transformation matrix is derived,the mathematical model of motor in synchronous rotation coordinate system is established,and the closed-loop vector control system model of single inverter and double inverter is established.The two-dimensional finite element model of the motor is established,and the no-load operation characteristics of the motor are simulated and analyzed.Based on the dynamic model of open winding six phase PMSM drive system,the maximum two vector PWM mode based on fundamental subspace is proposed,and the maximum two vector PWM mode of dual inverter drive system is analyzed.The space voltage vector and zero sequence voltage of single inverter and double inverter closed-loop vector control system are compared and analyzed.Through the derivation of the modulation coefficient range,the control strategy law is obtained and the Simulink simulation model is established.The output voltage under the control strategy is applied to the two-dimensional finite element model of the motor as the excitation.The operation characteristics of the motor under the control strategy are simulated and analyzed to verify the effectiveness of the SVPWM control method of the dual inverter drive system.In view of the common open circuit fault of multi-phase motor system,the fault-tolerant operation of the motor is realized based on the fault-tolerant control scheme of the minimum copper loss of the stator.The suppression of the winding magnetomotive force,copper loss,iron loss,eddy current loss,torque and torque fluctuation and torque fluctuation in the fault-tolerant operation of the motor is analyzed by the finite element model.The current waveform is compared with the other three topology structures The reliability of the fault-tolerant control strategy is verified by comparing and analyzing the current waveform of.In addition,by adjusting the amplitude and phase of the fundamental current,the torque fluctuation caused by the third harmonic back EMF can be restrained,and the non fault phase winding does not need to be injected with harmonic current,which improves the engineering practicability of fault-tolerant operation of polyphase motor.