Small Wind Power Systems Rectifier Unloading Design And Implementation Of The Load Device

Small wind power generation system is very suitable for solving the power problem of residents living in a relatively poor and scattered place but with a preferable wind sources. But, it develops slowly nowadays because of the its high cost and low reliability. Therefore, it is meaningful to study the small wind power generation system.The electric power that comes from wind is got feedback to the power electronic interface circuit of power grid by rectifier circuit. It plays a vital role in small wind power system as it has such characteristics as capacity, stability, and interconnection. Unloading circuit is used as the fan's protection circuit. It can protect the fan from speeding and overloading in strong wind case. Besides, the capacity requirement of power grid's front-end inverter is reduced after the introduction of unloading circuit. Thus the system cost is reduced. Therefore, the rectifier and unloading device of small wind power system is studied and designed in this thesis.Main research and work are as follows:1)The topological structure of small-scale wind power system and knowledge about rectifier and unloading technology are introduced. On the basis of this, system structure is given which is composed of permanent magnet synchronous generator, uncontrolled bridge rectifier circuit, unloading device and inverter.2) The functional requirements and design of system's rectifier and unloading device are analyzed and designed according to the topological structure and performance index of the system. The appropriate hardware components are seleted. Besides, a modified unloading circuit control method is put forward according to the existing control logic of unloading circuit.3)MSP430F149 microcontroller is used as the measurement control chip of system's rectifier and unloading circuits. The switch of unloading circuit and the size of unloading power are controlled through PWM waveforms which are calculated and generated according to the measured DC voltage.4) The rectifier circuit, IGBT driver circuit and buffer circuit are designed according to the rectifier and power switching devices selected before.