Space Vector Modulation for Circulating Current Suppression Using Deadbeat Control Strategy in Parallel Three-Level Neutral-Clamped Inverters

Parallel three-level T-type inverters (3LT
²
Is) can effectively increase the power rating. However, when multiple 3LT
²
Is are connected to a single dc bus, the zero-sequence circulating current (ZSCC) will occur. The ZSCC will distort the output currents and increase the system loss. To overcome this drawback, this paper proposes a novel deadbeat control scheme for the ZSCC suppression. A generalized model for analyzing ZSCC in parallel 3LT
²
Is is developed for designing the deadbeat control method. The proposed deadbeat control scheme is realized by real time adjusting the dwell time of small vectors in each space vector modulation. Compared to the conventional PI control method, the influence of different sector is eliminated, thus, improving the output current waveform and reducing the ZSCC. The effectiveness of the proposed method is verified by simulation and experiments.