The Research On Five-phase PMSM Control System For All-electric Aircraft

All-electric aircraft is a new type of aircraft which takes the electric system asflying power rather than the conventional fuel system, and the three-phase motor isoften used as the traction motor for its maturity in technology. By contrast, themultiphase motor has the advantages of high reliability, good performance offault-tolerance and low torque ripple. Therefore, this paper uses the five-phasePMSM as the traction motor of the all-electric aircraft. Later in this paper, themathematical model, SVPWM modulation, operation method under the open-circuitfault and the way to improve EMC ability of the drive system are studied, and boththe hardware platform and the software code of the five-phase PMSM controller arebuilt, finally the related experimensts are conducted.Mathematical model of the motor and the coordinate transformation are thebasis of motor control. Hence, this paper establishes the mathematical model offive-phase PMSM in the natural coordinate system. Then the coordinatetransformation formula of sinusoidal winding five-phase PMSM is deduced, so wecan obtain the mathematical model in the rotating coordinate system, and based onwhich both the motor itself and vector control system of five-phase PMSM areestablished in MATLAB/Simulink.SVPWM has been widely used in three-phase inverter system for its advantagesof low harmonic content, high utilization rate of bus voltage and easyimplementation by digital chip. Considering its characteristics, the SVPWMmodulation for the five-phase inverter is studied. And focus on the SVPWMmodulation method of Nearest Two Large Vector (NTV) and Nearest Four Vector(NFV), the analysis of simulation and experiment is carried out, from which themerits and demerits both in voltage utilization and harmonic content of the twoSVPWMs are studied.One of the basic requirements of the motor controller for all-electric aircraft isto keep functioning under the fault of open circuit ranther than stop right away. Thecontrol strategies of five-phase PMSM under fault condition are studied in this paper.Firstly, the modulation method under fault condition is presented. After thecomparison of the modulation method of SVPWM, the effective time carrier typePWM and the current hysteresis, we insist that the SVPWM is hard to use under thefault condition. Therefore, we decide to use the SVPWM under the normal conditionand the current hysteresis under the fault condition. At last, the demands whenworking under the condition of open-phase fault are deduced, and finally verified by simulation.What’s more, the EMC issues of the motor controller for all-electric aircraft arestudied in this paper. To improve the EMC ability, various measures are presentedfor the parts of the signal, the main circiut, the drive of IGBTs and the power fromthe perspective of engineering, and based on which the control platform is foundedand related EMC experiments are carried out.