Performance Improvement of Dual-Buck Inverter With Mitigating Reverse Recovery Characteristics and Supporting Reactive Power

This paper proposes a three-level dual-buck inverter (DBI) that reduces reverse recovery current and compensates reactive power. To reduce the reverse recovery problem of main switching diodes in the DBI, the auxiliary circuit consisting of diodes and coupled inductors is adapted. The auxiliary circuit enables zero-current turn-off of the diodes. The coupled inductor design is also conducted considering not only for unity power factor (PF) but also non-unity PF operations. By utilizing the auxiliary circuit, the reverse recovery and the shoot-through problems in silicon devices can be significantly mitigated so that the efficiency and the reliability of the DBI are much improved. Meanwhile, the pulse-width modulation scheme is also proposed to supply reactive power with the DBI which is a unidirectional inverter. In the proposed modulation method, the duty offset is simply added according to the required PF and the operating region of the DBI. By doing so, traditional current control concepts for bidirectional inverters can be directly applied to the DBI without any modification. By utilizing the proposed techniques, the reliability, efficiency, and utilization of the DBI can be significantly improved. The experimental results with a 3 kVA DBI prototype demonstrate the effectiveness of the proposed DBI.