Research On Internal Fault-tolerant Permanent Magnet Starter Generator System

With the rapid development of more-electric and all-electric aircraft in recent years, the requirements of aeronautical power system increases highly in terms of power level, power quality and reliability. Internal and integrated starter generator system has become the research focuses in more-electric aircraft system. The starter generator system is based on the reversibility principle of the motor. The motor works as the starter of the engine in electric mode and works as the load of the engine in generating mode to supply power. Fault-tolerant permanent magnet motor(FTPMM) takes the characteristics of high power density and high reliability. Thus, FTPMM is a strong competitor in the area of internal starter generator.The overall structure of internal FTPMM starter generator system is introduced. The mathematical model of FTPMM is established according to its features. Based on the aero engine start torque trait, the constant torque starting scheme is presented. Considering the large inductance of FTPMM, Id analysis flux-weakening control method is proposed to realize the constant voltage generation control in a wide speed range. Considering the magnetic isolation of FTPMM and based on the three-phase four-leg topology, the fault-tolerant control strategy of one-phase fault is proposed according to SVPWM algorithm. It means to keep the magnetic fields generated by stator current as circular rotating fields. On the basis of theoretical analysis, the simulation model of the FTPMM starter generator system is established by using the simulation analysis software MATLAB. The simulation analysis and verification of the control algorithm are carried out.The simulated hardware experiment platform of internal FTPMM starter generator system is designed and set up. It mainly includes the control circuits and power circuits. The core chip of the control circuits is TMS320F2812 of TI. The power device is the IPM of Mitsubishi. The software procedures of the control strategy is realized by C language program, which mainly include constant torque starting algorithm, flux-weakening control algorithm and fault-tolerant control algorithm. Based on the hardware and software, the whole starter generator system was debugged. Experimental results are in agreement with the simulation results and theoretical analysis,which verify the effectiveness of the control strategy of the system.