Four-level predictive control of two parallel converters based on inductance configuration

A common challenge in dual parallel converter operation is the difficulty in balancing circulating current and parallel current ripple. This paper proposes a stepwise model predictive control method for dual parallel converters based on inductor ratio matching. By configuring AC-side filter inductors with a 1:2 ratio, the method achieves 37 equivalent basic vectors through vector deduplication from 64 switching combinations without increasing power device levels, resulting in a four-level output vector plane. Building on this foundation, a discrete predictive model for parallel current and three-phase circulating current is established. The method first ranks vectors according to current ripple targets, then filters redundant combinations under constraints of three-phase and zero-sequence circulating current peak thresholds, achieving coordinated optimization of ripple and circulating current while maintaining controllable computational complexity. Simulation results demonstrate that under conditions where the equivalent filter inductors and switching frequencies are consistent, the proposed method significantly reduces parallel current ripple metrics and suppresses zero-sequence circulating current peaks compared to the 1:1 inductor ratio interleaved carrier space vector modulation (ISVM).