Research On Air Gap Flux Oriented Vector Control Techniques Of Synchronous Motor

Adjusting speed system of synchronous motor is widely used in the field of high-power electric drive. The high-performance speed control system of synchronous motor can realize industrial automation and improve production efficiency. Besides, it is also of great significance for power saving. This paper studies on the electrically excited synchronous motor vector control system which is based on air gap magnetic field orientated. The control system design and flux observer are analyzed in details.Based on the vector control principle and coordinate transformation tools, this paper analyzes the basic principle of air gap flux oriented control. In order to design the control system, the mathematic models in A-B-C frame, d-q frame and M-T frame for synchronous motor are established, and the overall bock diagram for synchronous motor vector control is given.According to the optimization design theory for control system, this paper designs the controller parameters for stator current regulator, speed regulator, rotor excitation current regulator and the air gap flux regulator. The stator current control is discussed in details. The dynamic and steady state performance of stator current is analyzed under different controller parameters. Based on the open-loop bode diagram, we find that PI controller for stator current loop is robust even if the motor parameters vary. And the EMF disturbance on the current loop control performance is also discussed. The control system performance is studied by simulation.The current model and voltage model for air gap flux observer are described, and an improved flux observer which is based on both the open-loop current model and the adaptive voltage model is designed. The PI controller for this flux observer is analyzed in detail. In order to evaluate the performance of this flux observer, this paper establishes complex vector model for the air gap flux observer, and uses the frequency response function for performance evaluation. The simulation results verify the theoretical analysis. Besides, the flux observer algorithm is also introduced. Based on the AC-DC-AC inverter and the DC chopper topology, this paper has designed an experimental equipment of synchronous motor speed control system. Verifications for the design of stator current regulator, speed regulator, rotor excitation current regulator, air gap flux regulator and the air-gap flux observer are done by experiment.