Optimal Inductor Current in Boost DC/DC Converters Regulating the Input Voltage Applied to Low-Power Photovoltaic Modules

Abstract

In energy-harvesting applications, inductor-based switching dc/dc converters are usually employed to regulate the operating voltage of the energy transducer and to transfer the harvested energy to a storage unit. In such a context, this paper analyses the optimal inductor current of the converter that leads to maximum power efficiency. This is evaluated assuming a lowpower photovoltaic (PV) module connected to a boost dc/dc converter operating in burst mode so as to reduce the switching losses. The theoretical analysis and the experimental results reported herein prove that this optimal inductor current does not depend on the power generated by the PV module provided that the control circuit is powered from the output, but it does on the output voltage level of the storage unit. Experimental tests with a commercial boost dc/dc converter show that the use of this optimal inductor current provides up to 10% increase in efficiency.Index Terms-Boost converter, burst mode, DC/DC converter, efficiency, energy harvester, photovoltaic module.

Design and Testing of a Kinetic Energy Harvester Embedded Into an Oceanic Drifter

“…In this work, the ADP5092 (Analog Devices) has been used as the core unit. This PMU is based on a boost regulator working on PFM mode [24] and with MPPT functionality. It is a lowpower module with a very low internal consumption and works with input voltages (V in ) as low as 80 mV.…”

Efficiency Optimization in Burst-Mode Buck DC/DC Converters for Sensor Nodes

“…In this scenario, PWM converters are not recommended either, especially for subwatt energy transducers. Control strategies based on PFM [16] and BM [17]- [19] are again preferable to reduce the switching losses and, hence, increase the efficiency. Taking into account the previous discussion, the overall power system of an energy-efficient sensor node can require [20]: 1) a first dc/dc converter regulating the input voltage (i.e.…”

“…The control strategies explained before have parameters that can be optimized to improve the converter efficiency, for example: an optimal gate-driving voltage [8] and an optimal size of the power transistors [11] in PWM, an optimal on-time or peak current in PFM [21], and an optimal inductor current in BM. The latter was studied for a boost topology when regulating the output [7] and the input [19] voltage. It was proved that there is an optimal inductor current to transfer the energy from the battery to the electronics (or from the transducer to the storage unit) during the burst.…”

“…Following the approach developed in [7] and [19], this paper optimizes the efficiency of a buck, instead of a boost, dc/dc converter operating in BM for both scenarios: input and output voltage regulation. Moreover, unlike [7] and [19], the model is extended considering that the quiescent current depends on the operating conditions of the converter.…”

“…Following the approach developed in [7] and [19], this paper optimizes the efficiency of a buck, instead of a boost, dc/dc converter operating in BM for both scenarios: input and output voltage regulation. Moreover, unlike [7] and [19], the model is extended considering that the quiescent current depends on the operating conditions of the converter. This analysis of the buck converter is of interest for prolonging the autonomy of low-power sensor nodes in which the supply voltage of the sensor electronics is lower than the storage-unit voltage and/or the operating voltage of the PV module is higher than the storage-unit voltage.…”