Non-linear control of the output stage of a solar microinverter. Issue 1 (2nd January 2017)

• Record Type: Journal Article
• Authors: Lopez-Santos, Oswaldo; Garcia, Germain; Martinez-Salamero, Luis; Avila-Martinez, Juan C.; Seguier, Lionel
• Is Part Of: International journal of control. Volume 90:Issue 1(2017)
• Page Start: 90
• Page End: 109
• Publication Date: 2017-01-02
• Subjects: sliding mode control -- photovoltaic microinverter -- power source inverter -- power electronics -- current controller -- power quality; Automatic control -- Periodicals; Electronic journals; 629.8
• DOI: 10.1080/00207179.2015.1116126
• Languages: English
• ISSNs: 0020-7179

Abstract

ABSTRACT: This paper presents a proposal to control the output stage of a two-stage solar microinverter to inject real power into the grid. The input stage of the microinverter is used to extract the maximum available power of a photovoltaic module enforcing a power source behavior in the DC-link to feed the output stage. The work here reported is devoted to control a grid-connected power source inverter with a high power quality level at the grid side ensuring the power balance of the microinverter regulating the voltage of the DC-link. The proposed control is composed of a sinusoidal current reference generator and a cascade type controller composed by a current tracking loop and a voltage regulation loop. The current reference is obtained using a synchronized generator based on phase locked loop (PLL) which gives the shape, the frequency and phase of the current signal. The amplitude of the reference is obtained from a simple controller regulating the DC-link voltage. The tracking of the current reference is accomplished by means of a first-order sliding mode control law. The solution takes advantage of the rapidity and inherent robustness of the sliding mode current controller allowing a robust behavior in the regulation of the DC-link using a simple linear controller. The analytical expression to determine the power quality indicators of the micro-inverter's output is theoretically solved giving expressions relating the converter parameters. The theoretical approach is validated using simulation and experimental results.