Research On The CPPM Hybrid Excitation Wind Power System

With the increasing emphasis on clean energy, wind power has become the world's fastest-growing new energy. China is the world's second largest energy consumer, and it import 50% of the oil every year. While resources and environmental issues are also increasingly prominent, to develop wind power is the inevitable choice.In wind power generation systems, permanent magnet synchronous motor with high-efficiency is attracting great attention. However, the air-gap flux of permanent magnet motor is difficult to control, which limit its application and popularization in many areas. In recent years, the hybrid excitation motor, especially CPPM motor is attracting more and more attention. It not only inherits high-efficiency characteristic of permanent magnet motor and also the advantage of motor with electrical excitation, which can adjust air-gap magnetic field smoothly. It can control the output voltage, expand the scope of wind speed and improve the efficiency of wind power generation.In this paper, firstly, the development of hybrid excitation motor and its control system are reviewed. The structure and operation principle of the CPPM motor are discussed. A two-dimensional simulation model is established by applying an equivalent method .For further accurate calculation of the magnetic field distribution of the motor, the three dimensional magnetic field finite element analysis are presented, and the simulation results of two-dimensional and three-dimensional are compared. Three-dimensional simulation focuses on the different parameters, which affect the waveform of flux density. The analysis gets the relationship between different parameters and the number of harmonic, providing reference for the motor design. Again, the paper introduces the wind turbine characteristics, and obtains the relationship between motor power curve and motor speed under different wind speed, which is called the maximum power point tracking (MPPT) control theory. Based on this theory, the system structure and control circuit implementation principle are proposed. And also the simulation software is used to help design the circuit, such as double-direction excitation circuit. Finally, experimental platform is constructed, experimental results show that the voltage waveforms of generator is sinusoidal and circuit works properly which match the motor voltage regulation ability.