Dual-Modulator Compensation Technique for Parallel Inverters Using Space-Vector Modulation

In common dc-link parallel-inverter systems, the amplitudes and the phase angles of three-phase inverters can be separately adjusted to control power sharing. However, when the space-vector modulation technique is used in a parallel-inverter system without the output transformers, the zero-sequence circulating current will occur. This paper provides detailed analysis of the zero-sequence circulating current and proposes a novel dual-modulator compensation technique for eliminating the zero-sequence circulating current caused by power-sharing control systems. Results obtained from both simulation and experiments confirmed the performance and the effectiveness of the proposed compensation method.