- 學位論文
單級低功率太陽能變頻器之研製
Design and Implementation of a Single Stage Low Power Photovoltaic Inverter
摘要
本論文主要是以數位訊號處理器來實現單級低功率之太陽能變頻器，為簡化系統嘗試將傳統串接之直流-直流與直流-交流轉換器的雙級變頻器結構簡化為單級之直流-交流變頻器。其中，以單相全橋之架構作為直流-交流轉換之核心，將低壓之直流輸入轉換為 / 之交流電壓輸出；為抑制輸出直流成份對輸出交流電壓之影響及不同電位系統之電氣隔離，因此於單相全橋電路之輸出端加入隔離變壓器。另外，為滿足單級控制之需求及降低高頻鐵損，因此使用鐵氧磁鐵來設計變壓器，將單相全橋電路輸出之 正弦脈寬調變電壓直接升壓至 ；為防止變壓器於脈寬調變期間之磁飽和，因此於變壓器高壓側輸出加入兩只搭配全橋切換訊號之同步整流開關，分別於60Hz正弦電壓之正半週與負半週來截止變壓器輸出，達到防止磁飽和之目的。於高壓輸出端設計一組LC低通濾波器與提供電感電流雙向續流所需之開關。 最後以所提設計製作一只輸入直流電壓35V及輸出為 / 之 變頻器做為驗證載具，証明所提策略之有效性。
並列摘要
The Object of this thesis is to design and implement a low power single stage PV inverter using DSP to replace the traditional DC-DC and DC-AC two-stage inverter. In the proposed inverter, the core converter is constructed by using a single phase full bridge which converts low-voltage DC to AC voltage with the frequency and . In order to eliminate the dc component injected to output voltage and make isolation between Photovoltaic cell and output, an isolated transformer is added at the output of full bridge. The transformer is designed by ferrite core owning to the low switching loss, and raises the sinusoidal PWM voltage yielded by full bridge to the grid side. Two switches, which are synchronized with the switching signals of full bridge and one of switches is conducted half period of sinusoidal voltage, are utilized at output path of transformer to prevent the transformer into saturation. Furthermore, a low pass LC filter and a set of switch as freewheeling path for the inductor is added near the output side to mitigate the switching noise. Finally, some experimental results tested in a self-made inverter, 35 input and /200 / output, show the effectiveness of the proposed control strategies.