[[alternative]]Design and Implementation of a Vector Controller for Inverter-Excited Induction Generator

碩士電機工程學系[[abstract]]早期的風能轉換方式是利用風力渦輪機去驅動感應發電機。為了提高效率，可以利用同步發電機來取代風力渦輪機，其變頻的輸出，再用直流連接型變流器，得到定頻的輸出。兩者的比較，前者需要有機械調速的裝置，故效率較低。但是，感應機的發電模式，本質上是變速定頻的發電系統，若能捨去機械調速裝置，改用其它方法適當地加以控制，應用在風力發電上將是一種效率高的風力發電系統。本文提出用變流器(Inverter)做為感應發電機的激磁電源，藉由控制感應發電機的激磁電流來控制感應發電機的輸出電力，因此不必經由機械調速裝置，也可以控制感應發電機的發電量，要改善風力發電的系統效率的目的是可以達到的。激磁電流的控制是利用感應機的直交軸理論，發展出一套向量控制的方法，來控制變流器依風速的變化適當地提供感應機所需的激磁電流，達到控制輸出電力的目的。本文的向量控制器是用數位信號處理器(Digital Signal Processor)來實現所提出的控制演算法，並且藉由實驗來證明變流器做為感應發電機的激磁電源的能力，在風力應用中，此系統在不使用風力渦輪機的情況下，成功地得到較佳的效率。[[abstract]]Wind turbine driving induction generators are conventionally used to convert wind power into electric power. Wind turbine generators have been improved using variable frequency synchronous generators converted using a DC link inverter to produce fixed frequency output. The former is less efficient because its speeds are regulated by a mechanical speed regulator. An induction machine operated in generator mode is inherently a variable speed constant frequency (VSCF) system. The most advanced wind generator system could be produced if the volatile wind power was used to directly drive an induction generator with the output power controlled using high efficiency control systems. This thesis proposes a scheme that eliminates the mechanical speed regulator. The proposed method uses an inverter designed as a current controlled source to supply magnetizing current for the induction generator to control the induction generator output power. The proposed method improves the wind power converting efficiency. The d-q axis theory is used to design a vector controller to control an inverter that appropriately supplies magnetizing current in accordance with the wind velocity to regulate the induction generator output power. The TMS320C240 digital signal processor (DSP) is used to implement the vector controller. The performers of the proposed control algorithms are examined and experiments to verify the ability of the proposed inverter to control the induction generator magnetizing current are illustrated. The proposed system successfully obtains higher induction generator efficiency without using a wind turbine in wind power applications