The Three-Port Three-Phase 3L-NPC Isolated Bidirectional DC-DC Converter

The multiport 3 level neural point clamped (3L-NPC) isolated bidirectional DC-DC converter (IBDC) can double the voltage level using the standard switching devices and connects different type sources together to meet the high-power application such as the ROV systems. A kind transformer coupled three-phase three-port 3L-NPC IBDC was put forward in this paper, and two operation modes were analyzed in detail according to the phase shift ratio and the duty cycle relationship. The regulating strategy of power flow for the three-port 3L-NPC IBDC was to get the minimum loss, hence the zero averaged power in the storage port and/or the zero-power flow between the storage port and load port were applied. The control was the multi-loop negative feedback of output voltage and current at the load port and a single-loop feedback of output current at the storage port. The linearization small signal mode was set up to analyze the control property and to determine the parameters. The three-port 3L-NPC IDBC can improve the electromagnetic compatibility obviously for high-power high-voltage application.