Passivity-based Control Of Brushless Doubly-Fed Machine

Brushless Doubly-Fed Machine (BDFM) has many advantages such as reliableoperation, small frequency converter capacity, flexible modulation of power factor andspeed. Therefore, it has good applicable prospect in the variable frequency speedregulation system and variable speed constant frequency generation system. However,one of the key factors to hinder its applications is the complex control structures andpoor control performance. Based on the Project of State Key Laboratory of PowerTransmission Equipment&System Security and New Technology of ChongqingUniversity, the simplified and high-performance control strategies of the BDFM withcage rotor were studied.Firstly, the basic structure and theory of BDFM were briefly introduced, and itsoperational characteristics were verified by the simulation of open-loop control (OLC).Then, the scheme of control winding fed by the current source inverter was adopted.6-order mathematical model of rotor speed dq-axis rotating frame was reduced as a4-order model, thereby the rotor flux oriented control system without torque estimationbased on the order-reduced model was established, which simplified the controlstructure and achieved the dynamic performances of speed and torque. Thirdly,according to the basic theory of passivity-based control (PBC), the Euler-Lagrangeequation of the BDFM with cage rotor was established and the system passivity wasanalyzed by the concept of energy. And then, a new torque and speed control structurewas proposed and the relevant controller was designed. Its dynamic performances werestudied by simulation and the parameter impact on the control performances was alsodiscussed. The results show that PBC has a good dynamic performance. Finally, thedynamic performances of OLC, rotor flux oriented control without torque estimationbased on the order-reduced model, direct torque control (DTC) and PBC were comparedrespectively. The results show that the OLC has a longer regulation time and a largerovershoot, the second control method has a smooth transition but less accuracy, DTChas more torque fluctuations, PBC shows excellent dynamic control performance.The study of this thesis has important reference value for the improvement ofBDFM’s control methods, and provides a foundation for the application of BDFM.