A High-Efficiency Single-Phase T-Type BCM Microinverter

Authors:
Publisher website
Google Scholar
Abstract
This paper proposes a high efficiency single-phase T-type BCM microinverter. The conventional full-bridge BCM microinverter has achieved ZVS soft switching and thereby improved the efficiency, but it suffers from high switching losses in light load conditions. The proposed T-type BCM microinverter reserves ZVS soft switching and uses multilevel technique to further decrease the switching losses. The BCM operation with multilevel technique will have too low switching frequency when the grid voltage approaches half of the DC link voltage. To solve this problem, this paper adopts a third operation mode for the T-type switching leg to maintain the switching frequency above a minimum value. The corresponding mode transitions are also detailed to ensure a smooth operation. Because of the turn-off delay of the freewheeling transistor, the actual lower current boundary deviates from the programmed one, which will distort output current. To address this issue, this paper also proposes a boundary compensation method. A prototype has been built for performance verification, which can test both full-bridge and T-type topology. Compared with the full-bridge BCM microinverter, the proposed T-type BCM microinverter has a higher efficiency over the whole load range.
Funding Information
  • National Key R&D Program of China (2016YFB0400504)
  • 2016 Grid State Science and Technology Program (NY71-16-027)

This publication has 29 references indexed in Scilit: