An Optimized MPC Method for Restraining the Midpoint Voltage Fluctuation of 3-Level T-Type Grid-Connected Inverter

• Published in: Journal of electrical engineering & technology Vol. 18; no. 2; pp. 1111 - 1122
• Main Authors: Dou, Zhifeng, Wang, Nan, Chen, Zhinan, Zheng, Anping, Lu, Falong, Lv, Zhongbin
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.03.2023; 대한전기학회
• Subjects: Electrical Engineering; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Instrumentation; Original Article; Power Electronics; 전기공학; Three-phase switch state; T-type grid-connected inverter; Cost function; Neutral point voltage fluctuation; Finite control set model predictive control
• ISSN: 1975-0102; 2093-7423
• DOI: 10.1007/s42835-022-01180-6

Conventional Finite Control Set Model Predictive Control (FCS-MPC) suffers from large neutral point voltage fluctuation, cumbersome calculation process, as well as high current Total Harmonic Distortions for 3-level T-type grid-tied inverter. An improved FCS-MPC method is proposed in this paper by directly calculating the switch state’s cost function. This method uses the 3-phase switching state S x to represent the load current i , the DC side neutral point voltage offset Δ U c , the load current prediction value i ( k  + 1), and establishes a real-time cost function g through 27 switching vectors. In the loop calculation, the switching vector is selected by minimizing the absolute value of the cost function g, and the output switching state is represented by the switching vector. Thus, the inverter can be switched ON or OFF depending on the stat of the next moment. The FCS-MPC of a 3-level T-type grid-tied inverter is also established by simulation, and the effectiveness of the proposed method is verified by experimental results.