Unfolding PV Microinverter Current Control: Rectified Sinusoidal vs Sinusoidal Reference Waveform

Diana Lopez Caiza, Samir Kouro, Freddy Flores-Bahamonde, Ricardo Hernandez

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

6 Citations (Scopus)

Abstract

Photovoltaic (PV) microinverter technology has become a popular solution in small-scale PV applications. The most used commercial microinverter topology is a two-stage converter composed by a dc-dc converter followed by a full-bridge unfolding inverter. The dc-dc-stage is in charge of performing MPPT and producing a rectified sinusoidal current waveform synchronized with the grid voltage, while the inverter stage only unfolds the current into an ac waveform. In this way no dc-link capacitor is needed (improving reliability), and only the dc-dc stage is performing PWM while the inverter stage is switching at fundamental frequency (improving efficiency). Since the reference current for the dc-dc stage is a rectified sinusoidal waveform, multi-resonant controllers are necessary. This type of controller is complex to design and requires more computational power compared to classic linear controllers, which is limited in PV microinverters, where lower-end micro-controllers are used to reduce cost. In this paper, a simple current control method is proposed, by following the opposite approach, in which a sinusoidal current waveform is controlled with easier controller design and implementation, and then folded or rectified in terms of the modulation in the dc-dc stage. The inverter stage unfolding function remains the same. In order to validate the proposed control, the interleaved flyback and push-pull unfolding PV microinverters are simulated, and the main features and differences of the traditional and proposed control are analyzed.

Original languageEnglish
Title of host publication2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages7094-7100
Number of pages7
ISBN (Electronic)9781479973118
DOIs
Publication statusPublished - 3 Dec 2018
Externally publishedYes
Event10th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2018 - Portland, United States
Duration: 23 Sep 201827 Sep 2018

Publication series

Name2018 IEEE Energy Conversion Congress and Exposition, ECCE 2018

Conference

Conference10th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2018
Country/TerritoryUnited States
CityPortland
Period23/09/1827/09/18

Keywords

  • Current control
  • Interleaved flyback converter
  • Microinverter
  • Photovoltaic energy
  • Push-pull converter
  • Unfolding inverter

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Renewable Energy, Sustainability and the Environment
  • Control and Optimization
  • Computer Networks and Communications
  • Hardware and Architecture
  • Information Systems and Management

Fingerprint

Dive into the research topics of 'Unfolding PV Microinverter Current Control: Rectified Sinusoidal vs Sinusoidal Reference Waveform'. Together they form a unique fingerprint.

Cite this