Research On Vehicle-based Doubly Salient Brushless DC Generator And Its Control Strategy

There are a lot of advantages of doubly salient generator, such as light weight, high efficiency, good heat dissipation performance, a long time working ability under relatively harsh environment, fast transient response,high power density and so on, which obtained the favour of motor designers. Doubly salient electro-magnetic Motor has a simple structure, and it's easy to control, which make the integration of generator and the rectifier equipment integration easily, and very suitable to be used as a vehicle-based generator.This thesis first introduces the performance requirements of the vehicle-based generator, research status and development trend of vehicle-based generator at home and abroad. By comparing the advantages and disadvantages of various types of vehicle-based generators, the most suitable method is chosen to satisfy the performance requirements of electric excitation doubly salient brushless dc generator. Then the basic structure of doubly salient generator is introduced, and the mathematical model of doubly salient motor is established. According to the requirements of the vehicle performance described in the design plan of generator, the noumenon of generator is designed. This thesis designs the motor with its number of pole pairs of stator and rotor, the ratio of stator pole width to polar distance, rotor pole width and rotor slot type. Main details of the key design of generator are provided in this thesis.The theory of the electromagnetic field for studying the motor is the most important theory. Ansoft simulation analysis as a finite element analysis software of electrical magnetic field is used most widely, so in this thesis at chapter four, the motor electromagnetic field theory and finite element software are introduced. This thesis uses the finite element simulation software to carry out a two-dimensional finite element analysis of designed generator, such as static magnetic field, no-load magnetic field, loaded magnetic field. The output voltage of generator is a important performance indicator, so in this thesis, simulations are made for the output voltage of the motor in Ansoft simulation software. The results show that the designed motor has a good performance, which conform to the requirements of the performance of the generator. Finally, the regulation system of electric excitation doubly salient brushless dc generator is designed. According to the nonlinear characteristics of electrical excitation doubly salient brushless dc generator, this thesis adopts the variable-parameter PI excitation control method, and gives out an easy implementation of variable-parameter PI excitation control algorithm. The excitation regulator circuit model which constitutes the entire power regulating system together with the generator model is constructed, and the voltage regulation control strategy is designed. Using the model to carry out simulation analysis under the abrupt change of load, the validity and correctness of the voltage regulator control method is verified.