High Step-up Transformer-less Inverter for AC Module Applications with Active Power Decoupling

Jinia Roy, Yinglai Xia, Raja Ayyanar

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

This paper explores a power conversion system for single phase transfomer-less 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 200V or 400V 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 lower switching and conduction loss for most of the switches. By directly connecting the grid-neutral to the PV negative, the doubly-grounded voltage-swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformer-less 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 120Hz 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-factor. The simulation as well as experimental results from a GaN based hardware-prototype validate the converter's performance.

Original languageEnglish (US)
JournalIEEE Transactions on Industrial Electronics
DOIs
StateAccepted/In press - Aug 3 2018

Keywords

  • Active power decoupling
  • Capacitance
  • Capacitors
  • doubly grounded inverter
  • extended duty ratio boost
  • Gallium nitride
  • GaN based converter
  • high gain boost
  • Inverters
  • microinverter
  • minimized capacitance
  • module integrated power converter
  • Reactive power
  • Stress
  • Switches
  • transformer-less PV inverter

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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