Research On Modelling Analysis And Electromagnetic Design Of Wound-rotor Brushless Doubly-fed Machine

As a new type of AC machines, Brushless Doubly-Fed Machine(BDFM) can achieve multiplicate operation mode, such as asynchronous,synchronous and doubly–fed operation mode. The BDFM avoids the useof brush and slip ring and has many advantages for its simple structure,such as flexible modulation of its power factor and speed, small capacity ofits frequency converter, etc. It has wide application in thecontrol-frequency saving-energy adjustable speed drive systems and theconstant-voltage constant-frequency variable speed generation systems,such as the fan and pump load drives， the wind power generation，and soon. However, due to the special structure and operation mechanism of thismachine, the electromagnetic design are also rather complicated, so it is inthe stage of the theoretical research and the completed electromagneticdesign program has not been seen. Based on the two projects which are TheNatural Science Foundation of Hunan Province and the Scientific andTechnological Project of Hunan Province, it focuses on the research ofmagnetic field modulation mechanism, finite element analysis,mathematical model and simulation, and the design of winding andelectromagnetic of BDFM with wound-rotor.First of all, based on the review of the history, the research status andthe prospects of BDFM done by the national and international scholars, thisdissertation has summarized the working principle, the winding structure,the operation mode and the power flow of BDFM with wound-rotor;Secondly, starting from the electric and magnetic circuits respectively, themagnetic field modulation mechanism of a BDFM with wound-rotor isresearched, then one finite-element model of this motor is established toverify the correctness of this mechanism; Thirdly, the d-q mathematicalmodel is deduced which based on the network mathematical model, thenthe simulation model of BDFM is build with the Matlab, and thecharacteristics simulation of various operation mode and power operationunder the light condition are carried out that verified the applicability of the BDFM mathematical model and theoretical analysis of the consistency.fourthly, the characteristic and design requirement of windings areinvestigated, and four design methods of wound rotor are generalized as“Conjugate Method”,“Pole-Changing Method”,“tooth Harmonic Method”and “Pole-Amplitude Modulation Method”, a new type winding is alsopresented for three-phase rotor design which can assure the equality of theinduced branch EMF and satisfy the demands of other electrical properties;fifthly, the problems in general principle of BDFM with wound-rotor arestudied, such as the choice of the pole-pairs number, the choice of theelectromagnetic loadings and the confirmation of the main dimension andso on, the electromagnetic design flow chart of this machine is presented,and an electromagnetic design software of this wound-rotor BDFM isdeveloped on the platform of Visual Basic6.0.Finally, a prototype machine of wound-rotor BDFM with Y180Lframe size,54/36slots and3/1pole pairs is designed and the performancesof this machine under varied operation modes are studied by theexperiment.The experimental data from above have shown that theproposed mathematical model and electromagnetic design calcuationprogram are validated, and have verified the feasibility of such a woundrotor structure.