Research On Characteristics And Control Method Of Current Source Fed Induction Motor

Voltage source converter is used widely in the field of induction motor drive now.However,its applications are restricted by poor load current limitation capability and four-quadrant operation limitation.Current source converter has several advantages,such as controlling the output current directly,realize regenerative braking easily,reliable four-quadrant operation and implicit short-circuit protection.But the large volume,high cost storage inductor used in current source converter is not conducive to the promotion and application of current source converter.In recent years,with the rapid development of the super-conducting magnetic energy storage technology,the efficiency problem of the current source converter will be resolved,which supply advantages for the current source converter in applications.Current source fed induction motor drive is presented in this dissertation.The electromagnetic mechanism,mechanical properties,current source converter topology,mathematical model,system design,efficiency optimization and simulation experimental results of current source fed induction motor drive are given in detail.The detailed content is arranged as follows:Electromagnetic interaction principle of current source fed induction motor is studied and rotor reaction diferences between voltage source fed induction motor and current source fed induction motor are analyzed.Diagram of space-vector for current fed induction motor under different load is presented and maximum boundary limitation of the magnetomotive force is given which lay the foundation for the design of current source fed induction motor.The theory of symmetrical components is used to derive the equivalent circuit and basic formulas of current source fed induction motor.Mechanical properties,overload ability and maximum torque of current source fed induction motor are also analyzed compared with voltage source fed induction motor.The performance change of the current source fed induction motor under different loads is verified by MATLAB,including motor speed,electromagnetic torque,stator current,stator voltage,power factor,input power and efficiency.The co-simulation method combined Ansoft/Maxwell 2D and Ansoft/Simplorer is applied to present the magnetic field chang of current source fed induction motor.The main circuit of the current source converter is designed.The transformation from bi-valued logical signal of voltage source converter to tri-valued logical signal of current source converter is studied.The space vector control strategy of current source converter is determined.The simulation results show that the unity-power factor of the grid side is achieved and the current ripple at the DC bus is small.In order to improve the response and steady state performance,the fuzzy self-adap PI speed regulator in vector control system of current source fed induction motor drive is designed and simulated.Based on the loss model and the golden section method,a hybrid search method is proposed to optimize the efficiency of current source fed induction motor drive.Simulation results show that the hybrid search method has advantages of independent on motor parameters,fast optimization speed and fast response,therefore,it is an effective efficiency optimization control algorithm.An experiment prototype based on DSP for current source fed induction motor drive is built.Hardware components and software designing methods are given in detail.The simulation and experimental results show that the feasibility of current source fed induction motor drive and the correctness of theoretical analysis.