Design And Realization Of Dual PWM Frequency And Speed Converter Of Brushless Doubly-fed Machine

Brushless Doubly-Fed Machine(BDFM)is an AC motor with special structure and operating principle.It has expansive applicable potentials in the field of variable frequency drive system.In the BDFM drive control system,it is necessary to use dual PWM converters to realize the variable frequency speed control of BDFM and meets the demand the bidirectional energy flow of BDFM control winding.However,the fluctuation of the DC bus voltage of dual PWM converter will endanger the reliable operation of the converter and influence the speed control performance of BDFM.Therefore,this thesis applied dual PWM converter to BDFM variable frequency speed regulation.To suppress the DC bus voltage fluctuation generated during the BDFM speed regulation process,according to the principle of variable frequency speed regulation of BDFM and the control theory of dual PWM converter,a BDFM dual PWM frequency and speed converter and its coordinated control algorithm were researched by the method of combining MATLAB simulation and prototype experiment.Firstly,this thesis introduced the operating principles of BDFM and three-phase voltage source PWM rectifier,derived the mathematical models of BDFM with cage rotor and three-phase voltage source PWM rectifier,and then analyzed the power flow direction of BDFM dual PWM frequency and speed converter.Secondly,according to the theory of instantaneous power,the instantaneous power equations of three-phase voltage source PWM rectifier and BDFM control winding were deduced,and then the load power feedforward coordinated control algorithm of BDFM dual PWM frequency and speed converter was designed.Thirdly,the main circuit parameters of BDFM dual PWM frequency and speed converter were designed according to the parameters of a BDFM prototype.The independent control and the load power feedforward coordinated control algorithms were compared and analyzed by simulation,and the optimization effect of the coordinated control algorithm was analyzed.Finally,with TMS320F28335 as the main controller,coupled with IGBT and isolation drive modules,the voltage,current and speed sampling circuits were designed.The BDFM dual PWM frequency and speed converter experiment platform was then built up.By using the designed experimental platform,the load power feedforward coordinated control experiment of BDFM dual PWM frequency and speed converter was carried out.The results show that the BDFM dual PWM frequency and speed converter designed in this thesis has the advantages of high power factor and bidirectional energy flow,and is suitable for BDFM frequency conversion and speed regulation.The load power feedforward coordinated control algorithm of BDFM dual PWM frequency and speed converter can reduce the DC bus voltage fluctuation during the BDFM speed control process,accelerate the response speed of the DC bus voltage,and improve the stability of the system.The research results of this thesis provide important technical reference and hardware support for the research on the control algorithm of BDFM dual PWM frequency and speed converter.