Research On Starter/Generator Control Strategy Of Aviation PMSM Fed By An ANPC Three-level Inverter

Starter/generator(S/G)system can greatly improve aircraft power density and integration.Therefore,it has become a research hotspot of the more electric aircraft(MEA)technology.Because of more cables,big weight,low efficiency,high cost and other problems in the S/G system of AC power supply,some key technologies of the S/G system of aviation permanent magnet synchronous machine(PMSM)fed by the active neutral point clamped(ANPC)three-level converter are studied by using the advantages of HVDC power supply system in this paper.Firstly,ANPC three-level converter topology is selected fit for the S/G system,and its neutral-point capacitor voltage balancing control strategy is analyzed.After some aspects of typical diode NPC,active NPC and TNPC three-level converters,such as topological structure,the harmonic characteristic,the power loss,the snubber circuit design and so on,are mutually compared and analyzed carefully,and the ANPC threelevel topology is obtained,which is suitable for the S/G system.The four-quadrant operation ability of ANPC three-level converter is analyzed because the S/G system can work either in rectification or in inverter.In order to solve the unbalance problem of upper and lower dc-bus capacitor voltages of ANPC three-level converter,the control strategy of neutral-point potential balancing is proposed.Secondly,through the analysis of resonance phenomenon in the practical application,the improved PDPWM modulation strategy is put forward.Using the traditional PDPWM modulation strategy,the absorption capacitance and the stray inductance of the circuit will produce resonance phenomenon,it will reduce the efficiency of ANPC three-level converter.To suppress the resonance,an improved PDPWM modulation strategy is proposed,and the corresponding simulation and experiment has proved its correctness.Furthermore,based on the above research,the control strategy of S/G system of aero PMSM powered by ANPC three-level converter is studied.ANPC three-level converter is combined with aero PMSM to constitute the S/G system.According to the working demands of PMSM S/G system,the system operation is divided into starting and generating processes.Based on the vector control of the motor,the control strategies of outside loops of speed,constant torque and constant power are proposed for the starting area.And the motor vector control algorithms before weak magnetic region and in weak magnetic region are analyzed for high speed generating process.At the same time,for the reliability of S/G system,the model reference adaptive sensorless control is selected as the backup of the system.The results of simulation have verified the corresponding control strategy of the S/G system.Finally,an experimental platform was designed for experimental verification.Based on the analysis and design,the high current experimental platform was built to verify the performance index of aero PMSM S/G system which ANPC three-level converter must reach.And the towing platform of ANPC three-level converter aero PMSM S/G system is built to verify the feasibility of relevant control strategies in the above three aspects.