Modified T-Type Three-Level AC-DC Converter Based Multifunctional Compensator for Three-Phase AC Power System With Low-Frequency Pulsed Load

• Published in: IEEE transactions on industrial electronics (1982) 2022-12, Vol.69 (12), p.11844-11855
• Main Authors: Zhu, Jianxin, Wu, Hongfei, Li, Lin, Wang, Jiangfeng, Hua, Ming, Xing, Yan
• Format: Article
• Language: English
• Subjects: AC-DC converters; Active filters; Capacitors; Carrier-based pulsewidth modulation (CBPWM); Circuits; Compensation; Compensators; Control methods; Decoupling; Dynamic response; Electric potential; Electric power systems; Feedforward control; Harmonic analysis; Inverters; Low pass filters; Power flow; Power harmonic filters; power quality; Power rating; Power systems; pulsed power decoupling; Rectifiers; semi-two-stage ac-dc converter; Voltage
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2021.3130322

In order to achieve an efficient pulsed power compensation for the ac-sourced pulsed power system, a multifunctional compensator (MFC) of modified T-type semi-two-stage converter is proposed in this article. The power decoupling capacitor is in parallel with one of the dividing capacitors of the three-level ac/dc converter, so that the voltage of decoupling capacitor is able to vary in a very wide range without increasing the voltage stress of the converter. The semi-two-stage compensator achieves better compensation performance and less decoupling capacitor than the single-stage circuit while having higher efficiency and lower converter power rating than the two-stage solution. Operating principles of the semi-two stage MFC are analyzed in detail, and a modulation strategy is presented to achieve two-path power flow between the decoupling capacitor and ac power system. In order to improve the dynamic response of the MFC during the transition between different pulse frequency loads, a power-difference feed-forward control and a dual low-pass filter control are proposed for the compensation. A prototype is built and tested to verify the effectiveness and feasibility of the proposed MFC and control methods.