- 學位論文
非對稱控制技術於全橋式零電壓感應加熱器之應用
Applying Asymmetrical Control Technology for Full-Bridge Zero-voltage-Switched Induction Heater
摘要
感應加熱設備在金屬加工製造上，相較於傳統加熱方式具有可控性佳、加熱特性良好與潔淨的加熱環境等諸多優點，但其電力架構之電源轉換效能尚有改善空間，因此在本論文中，我們將非對稱控制技術應用於感應加熱設備上，並針對感應加熱設備整個設計流程包含全橋共振返流器、非對稱控制電路、隔離驅動電路、串聯諧振負載及柔性切換技術做一完整的分析與討論。 本論文之電力架構採用全橋串聯諧振電路，以供應感應加熱線圈所需之交變電流，再透過隔離輸出變壓器將能量轉移至二次側線圈上，以提升加熱線圈效率。本電路的設計方面，可藉由串聯諧振的分析，獲得諧振槽的匹配與元件選取條件，進而得到零電壓切換條件的設計方針。在驅動電路的設計方面，採用光耦合電路搭配電流放大器，以確保控制器的訊號能以較不失真的訊號控制切換元件，並能在所需的操作頻率下正常工作。非對稱控制器的設計方面，本論文以鎖相積體電路做為震盪核心，透過電流偵測器所回授的電流訊號與電壓訊號，比較相位結果來修正操作頻率的輸出，避免負載變動劇烈，造成切換元件上的應力提升，整個非對稱控制電路的製作採用純類比電路完成。 最後，藉由波形的驗證，證實非對稱全橋感應加熱器，在變頻控制下，由滿載至輕載，皆能實現零電壓切換條件。本論文完成一具，輸出功率為3kw，操作頻率為100kHz~200kHz之非對稱式感應加熱設備雛型機。
並列摘要
The main purpose of this dissertation is to design and manufacture the new high frequency induction heater. Compared with the traditional heater, there are a lot of advantages for the induction heater including: easy control, good heating performance, clean heating environment. But power-conversion efficiency of its power structure still needs to improve. Therefore, the dissertation applies the technology of asymmetrical voltage-cancellation control to reform the induction heater Equipment. The whole design procedure of induction heating is also shown in this dissertation including: full bridge inverter, asymmetrical voltage cancellation controller, electrical isolated MOSFET driver circuit, series resonant converter and soft-switching topologies. The power circuit structure uses a full-bridge series resonant inverter to supply the exchange current for the heating coil of this induction heater. Next, the current power is transferred to secondary coil through the isolation output transformers in order to improve the efficiency of induction heat. In the circuit design, the matching condition and the resonant tank and selected direction of all devices are obtained by using the analyzed results of series resonant such that the design goal of zero-voltage switching condition is achieved. In the driver circuit design, the electrical-isolated accompanied is used with current amplifier to make sure that the control signal to operate switching devices without signal distortion under the required switching frequency. In the asymmetrical voltage-cancellation controller design, the phase-locked loop IC is used as the oscillator core. The current and voltage signals are used to compare the phase results to correct the output of switching frequency to avoid the severe change of load. The asymmetrical voltage-cancellation controller is achieved by the analog circuits. Finally, the zero-voltage switching condition of AVC full-bridge induction heater is proved by using the confirmations of the signal waveforms under the variable-frequency control from high load to light load. The AVC induction heater is finished with the 3kw power output and 100kHz~200kHz switching frequency.