A CMOS-Based Energy Harvesting Approach for Laterally Arrayed Multibandgap Concentrated Photovoltaic Systems

Abstract

This paper presents an energy harvesting approach for a Concentrated Photovoltaic (CPV) system based on cellblock-level integrated CMOS converters. The CPV system, built upon the Laterally-Arrayed Multi-Bandgap (LAMB) cell structure, is a potentially higher-efficiency and lower-cost alternative to traditional Tandem-based systems. The individual cells within a sub-module block are connected for approximate voltage matching, and a Multi-Input Single-Output (MISO) buck converter harvests and combines the energy while performing Maximum Power Point Tracking (MPPT) locally for each cell type. A miniaturized MISO dc-dc prototype converter operating at 10MHz is developed in a 130nm CMOS process. For 45-160mW power levels, the prototype converter achieves >92% nominal and >95% peak efficiency in a small (4.8 mm 2 ) form factor designed to fit within available space in a LAMB PV cell block. The results demonstrate the potential of the LAMB CPV architecture for enhanced solar energy capture.Index Terms-MISO dc-dc converter, energy harvesting, concentrated photovoltaic systems, maximum power point tracking, CMOS dc-dc power converters

Overview of DC/DC Converters for Concentrating Photovoltaics (CPVs)

“…Even extreme efficiency allowed by the differential power processing of [36] cannot overcome the intrinsic over cost due to the numerous amounts of converters needed to fully cover all of the cells. From these three converters, only the one in [38] does not meet the requirements of minimum mandatory efficiency, the one in [32] being at the limit. It has to be noted that to derive the efficiency curves in Figure 8, only the efficiency relative to power electronic itself is considered.…”

“…The four other converters implement very simple MPPT algorithms, mainly in order to validate their hardware: in refs. [31,32], a Perturb and Observe algorithm is implemented, in [38], a hill climbing algorithm is implemented, and in [36], a simple voltage equalization technique is employed. Hence, the focus of the present overview is restricted to discussions related to hardware.…”

“…As designed, the buck and boost topologies exhibit a unitary complex factor, followed closely by the buck boost topologies (which trades a diode for a switch compared to buck or boost). The most complex topologies, namely [32,34], show complexities three times or higher than the simplest ones.…”

“…The more complicated ones represent attempts at answering some specificities of the CPV cells, and are represented in Figure 6. For example, in [32], it consists of an interleaved buck topology. Each of its input is directly linked to a junction of the CPV cell, mainly to overcome spectral mismatch and the necessity of lattice-matched junctions [33].…”

Impact of DC-DC Converters on the Energy Performance of a Dense Concentrator PV Array under Nonuniform Irradiance and Temperature Profiles

“…However, it is worth noting that these DC-DC converters only supply the mismatch current between the series current and the maximum power point current of each CPV cell. Consequently, their efficiency and power output are reduced compared with traditional converters that facilitate full power conversion [29][30][31].…”