Study On The Three-level Direct Torque Robust Control Strategy In Permanent Magnet Synchronous Machine Drives

An adjustable-speed drive system of the high-power permanent magnetsynchronous motors has been investigated in this thesis, in which the dual three-levelneutral-point-clamped AC-DC-AC topology is used as frequency converters. A robustcontrol strategy of three-level PWM rectifier is proposed in this thesis. A permanentmagnet synchronous motor space vector modulation direct torque nonlinear robustcontrol strategy is proposed based on L2gain in this thesis. A rapid estimation methodof initial rotor position for saliency permanent magnet synchronous motor is proposedin this thesis and this method performs well in engineering. A flux observer is appliedbased on hybrid voltage-current model in this thesis, which enjoys two advantages,the integral drift problem can be eliminated by an improved integrator in the voltagemodel, and moreover, the estimated flux can be corrected with the current model toachieve full speed flux estimation. The designed controllers and estimation methodsare verified by simulation and experimental results.