Enhancing Microinverter Energy Capture With Submodule Differential Power Processing

• Published in: IEEE transactions on power electronics Vol. 31; no. 5; pp. 3575 - 3585
• Main Authors: Shibin Qin, Barth, Christopher B., Pilawa-Podgurski, Robert C. N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithm design and analysis; Architecture; Converters; Detection; Electric currents; Electric power; Electronic systems; Energy capture; Hardware; Inverters; Maximum power point trackers; Power loss; Prototypes; Sensors; Tracking; Transaction processing; Voltage control; maximum power point trackers; Differential power processing; power systems; power converters; micro-inverter; photovoltaic
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2015.2464235

Differential power processing (DPP) is a power electronics system architecture that configures dc-dc converters in parallel with the PV string to improve its power yield. The parallel nature of the DPP architecture brings a number of benefits, such as low converter power rating and low power losses, all of which make DPP especially suitable for submodule-level maximum power point tracking (MPPT). Meanwhile, microinverters typically perform only module-level MPPT and do not address power losses due to uncompensated submodule mismatch. In this paper, we introduce DPP converters into a microinverter system to improve its energy capture by recovering power losses due to submodule mismatch. The control method to interface DPP converters with a microinverter for submodule MPPT is presented and the tradeoff between tracking accuracy and control overhead is analyzed. A small-footprint DPP converter is designed. A digitally assisted windowed sensing technique is also implemented to address the challenge of precise current sensing. Altogether, the proposed solution seamlessly integrates DPP into the existing microinverter design. To demonstrate the effectiveness of the proposed solution, a hardware prototype has been built and tested with an off-the-shelf commercial microinverter. The improvement in energy capture with DPP converters has been experimentally verified.