Mehmet UÇAR, Emre AVCI

3-Seviyeli 3-Fazlı 4-Kollu AT-NPC Eviricinin SRF Tabanlı Çıkış Gerilimi Denetimi

Bu çalışma bağımsız modda çalışan 3-seviyeli 3-fazlı 4-kollu (3P4L) gelişmiş T-tipi nötr noktası bağlantılı (AT-NPC) evirici için senkron referans yapı (SRF) tabanlı yüksek performanslı çıkış gerilim denetleyicisi önermektedir. Bağımsız işletim için 3-fazlı eviriciler, dengesiz doğrusal ve doğrusal olmayan yükler gibi farklı yük türleri altında 3-fazlı dengeli nominal gerilim sağlamak zorundadır. Bu tür yüklerle çalışan 3P4L eviriciler, ilave dördüncü kol tarafından sıfır sıralı gerilimi kontrol etmeye izin verirler. Bu çalışmanın ana katkısı, senkron koordinat sisteminde çıkış gerilim ve kondansatör akım geri beslemesine dayalı olarak modellenmiş LC tipi filtreye sahip 3-seviyeli 3P4L AT-NPC eviricinin kontrol edilmesidir. Elde edilen kondansatör akımı ayrıştırılmış modele göre, eviricin çıkış gerilimini kontrol etmek için çift çevrimli PI denetleyicisi adapte edilmiştir. Hızlı dinamik cevap ve kapasitör akımının aktif sönümlenmesi için kapasitör akım geri beslemeli bir iç döngü kullanılmıştır. Son olarak, denetleyicinin geçici ve kararlı durum çalışma performansı, farklı yük türleri dikkate alınarak PSIM benzetim çalışmaları ile test edilmiştir. Benzetim sonuçları, önerilen SRY tabanlı çift döngülü PI denetleyicinin, 3-seviyeli 3P4L AT-NPC evirici için %3’den daha düşük toplam harmonik bozulma (THD) değerine sahip yüksek dinamik cevap ve yüksek kaliteli çıkış gerilimi sağladığını doğrulamaktadır.

SRF Based Output Voltage Control of 3-Level 3-Phase 4-Leg AT-NPC Inverter

This paper proposes a synchronous reference frame (SRF) based high performance output voltage controller for the 3-level 3-phase 4-leg (3P4L) advanced T-type neutral point clamped (AT-NPC) inverter operated in stand-alone mode. 3-phase inverters for stand-alone operation are required to provide 3-phase balanced nominal voltage under different load types such as unbalanced linear and non-linear loads. 3P4L inverters working with these types of load allow controlling zero sequence voltage by additional fourth leg. The main contribution of this work is the control of the 3-level 3P4L AT-NPC inverter with an LC-type filter modeled based on the output voltage and capacitor current feedback in the synchronous coordinate system. According to obtained capacitor current decoupled model, double loop PI controller is adopted to control the output voltage of the inverter. An inner capacitor current feedback loop is employed to provide fast dynamic response and active damping of the capacitor current. Finally, transient and steady state operation performance of the controller have been tested with PSIM simulation studies considering different load types. Simulation results validate that the proposed SRF based double loop PI controller ensure high dynamic response and high quality output voltage with less than 3% total harmonic distortion (THD) value for the 3-level 3P4L AT-NPC inverter.

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