High Step-Up Transformerless Inverter for AC Module Applications with Active Power Decoupling

Jinia Roy, Yinglai Xia, Raja Ayyanar

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

This paper explores a power-conversion system for single-phase transformerless ac module application. A nonisolated high-gain dc-dc stage is coupled with a doubly grounded dynamic dc-link inverter to implement the microinverter topology. The front-end boost stage steps up the single-module voltage to a higher dc voltage, typically to 200 or 400 V as required for the following inverter stage. It is a hybrid of an interleaved boost and switched capacitor concept capable of achieving high gain while simultaneously maintaining reduced voltage and current stress, and thus lowering switching and conduction loss for most of the switches. By directly connecting the grid neutral to the photovoltaic (PV) negative, the doubly grounded voltage swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformerless PV inverters. The two dc links of the inverter stage share the double-line frequency power decoupling with a combination of higher value of mean voltage and relatively large 120-Hz ripple component-the dynamic dc-link approach. Through an optimization algorithm, the decoupling capacitance is minimized enabling an all-film capacitor implementation while satisfying the converter's operating constraints over a wide range of power factors. The simulation as well as experimental results from a GaN-based hardware prototype validate the converter's performance.

Original languageEnglish (US)
Article number8425065
Pages (from-to)3891-3901
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Volume66
Issue number5
DOIs
StatePublished - May 2019

Keywords

  • Active power decoupling
  • GaN-based converter
  • doubly grounded inverter
  • extended-duty-ratio (EDR) boost
  • high-gain boost
  • microinverter
  • minimized capacitance
  • module-integrated power converter
  • transformerless PV inverter

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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