The Electromagnetic Design And Operation Characteristics Research Of The Wound Rotor Brushless Doubly Fed Machine

With the object of the wound rotor Brushless Doubly-Fed Machine (BDFM), the aims of the research is listed in the following several aspects. The first is to establish the dq0 mathematical model with the rotor speed and simulate the operation characteristics in the Matlab software when the machine is used as a motor operating in single fed asynchronous operation, DC synchronization, doubly-fed low synchronous operation and doubly-fed super synchronous operation. The second is to analyze the power generation characteristics by using the equivalent circuit method and the finite element analysis. The third is to research the power generation characteristics of the three different rotor structures of the BDFM with the help of the finite element method.In the dissertation, the main works are as follows:Firstly, the operation principles of the wound rotor BDFM are analyzed and the rotor rotation speed expression of the stable running, and the power allocation and flow direction between the PW and CW are illustrated. And several operation modes of the machine are introduced.Secondly, the stator and rotor winding inductance of the BDFM, the mutual inductance between them are given. The winding voltage and flux linkage expressions are formulated. The dy0 mathematical model with the rotor speed of the machine is established and the characteristics of the several operation modes of the machine are simulated in the Matlab software when the machine is used as a motor. The common used per phase equivalent circuit of the machine is given. And based on the simplified per phase equivalent circuit, the torque-angles and the reactive power regulation characteristics of the BDFM are analyzed in detail.Then, the winding designs and the MMF characteristics of the stator and rotor are illustrated in detail. A double-sine winding is designed basing on the tooth harmonic principle and the sine winding theory. And the harmonic contents of the rotor winding are analyzed. The power generation characteristics of the BDFM with different rotor speed when the PW are connected to different loads are analyzed by using the equivalent method and finite element analysis. The calculation results are compared.Following, the power generation characteristics of the three different rotor structures of the BDFM are analyzed with the help of the finite element method when the PW are connected to the same load..Finally, a 60kW BDFM introduced in this paper is used as a prototype machine. The PW voltage, frequency and the waveform THD are tested when the PW is in no load and different loads conditions. When the PW is in full load condition, the line voltage, the total active power and the line current relationships with the rotation speed of the PW and CW are figured.