A High-Efficiency Hybrid Resonant Converter with Wide-Input Regulation for Photovoltaic Applications

Abstract

A microconverter serves as a front-end dc-dc stage of a microinverter to convert the power from a photovoltaic (PV) module to a dc-bus. These front-end microconverters require isolation, high-boost ratio, wide-input voltage regulation, and high-efficiency. This paper introduces an isolated resonant converter with hybrid modes of operation to achieve wide-input regulation while still maintaining high-efficiency. The proposed converter is designed as a series resonant converter with nominal-input voltage and operates under two additional modes: a boost converter with low-input voltage and a buck converter with high-input voltage. Unlike conventional resonant converters, this converter operates at discontinues conduction mode (DCM) with a fixed frequency, simplifying the design and control. In addition, this converter can achieve zero-voltage switching (ZVS) and/or zero-current switching (ZCS) of the primary-side MOSFETs, ZVS and/or ZCS of the secondary-side MOSFETs and ZCS of output diodes under all operating conditions.

Existing System

Maximum Power Point Tracking Technology.

Proposed System

In this paper, a resonant microconverter with hybrid operation modes is proposed to achieve high-efficiency and wide-input voltage regulation. This microconverter topology operates as a series resonant converter at the nominal-input voltage where it reaches peak efficiency. Two operation modes combine to allow the converter to operate on either side of this optimized point. Under low-input voltage, the converter behaves as a boost converter. A new switching technology is proposed under this condition to allow simple control, and reduced switching and gate charge loss. Under high-input voltage, the converter acts like a buck converter. The switching frequency is fixed at the series resonant frequency during the entire operating range. With this topology, the converter achieves ZVS and/or ZCS of the primary-side MOSFETs, ZCS and/or ZVS of the secondary-side MOSFETs and ZCS of the output diodes under all operating conditions.

Architecture

Proposed microconverter topology with hybrid modes of operation