A modified SVPWM strategy applied to a three-phase three-port bidirectional AC-DC rectifier for efficiency enhancement

A three-phase three-port rectifier (TPTPR), which is capable of handling an AC port, a low voltage DC port and a high voltage DC port simultaneously, is presented in this paper. To directly transfer power from the AC port to the low voltage DC port within single-stage power conversion, a modified SVPWM strategy based on asymmetric three-level vector space is analyzed and evaluated in this paper. With the TPTPR and modified SVPWM control strategy, the low voltage port with wide voltage range can obtain energy directly from the AC grid. As a result, the power conversion stages are reduced and the power rating of the downstream DC-DC converter can be reduced significantly. The presented topology and its corresponding vector space are both different from those of traditional two-stage rectifier composed of a three-phase three-level rectifier and a cascaded DC-DC converter. A 5kW prototype with fixed high voltage DC port and a variable low voltage DC port is built and tested to verify effectiveness of the presented solution.