Input-Series-Output-Parallel-Connected Buck Rectifiers for High-Voltage Applications

This paper presents input-series-output-parallel (ISOP) configuration for single-phase front-end buck rectifiers (BRs). The configuration is especially suitable for traction applications, where the complete rectification system needs to withstand high ac voltages and supply medium-power loads. The primary rectification module of the proposed configuration is based on pulsewidth-modulated BR (current source inverter topology). The desired isolation, mandatory for ISOP connection, is provided at the dc stage through a medium-frequency/high-frequency transformer. Equal power sharing by modules is achieved from the ac side through input voltage and current sharing. The proposed control scheme is configured using two loops. While the outer loop regulates the output dc voltage and active wave shaping of the source current, the inner loop ensures stable voltage sharing. The performance of the proposed ISOP configuration is verified using numerical simulation. Experimental verification is achieved through a 2-kW grid-connected laboratory prototype.