scholarly journals Low-power electronics for energy harvesting sensors

2014 ◽  
Vol 1 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Steven Dunbar ◽  
Zoya Popović
Keyword(s):  
Energy Harvesting ◽  
Low Power ◽  
Low Voltage ◽  
Integrated Design ◽  
Storage Element ◽  
Fully Integrated ◽  
Point Tracking ◽  
Transient Nature ◽  
Power Point ◽  
Power Application

This paper addresses low-power, low-voltage electronic circuit requirements for wireless sensors with energy harvesting. The challenges of start-up for micro-controller unit (MCU)-based energy-harvesting platforms is discussed where a transient, low-voltage (20–1000 mV), low-power (<100 μW) source having a relatively high source impedance (possibly >500 Ω) is used. Efficient converter circuitry is required to transform the low-voltage output from the source to a level suitable for typical electronic devices, 1.8–5 V, and a prototype is demonstrated in the paper. Owing to the limited energy available to deliver to the storage element, the converter output voltage typically has a slow rising slew rate that can be a problem for MCUs. This necessitates a reset circuit to hold-off operation until a level high enough for reliable operation is achieved. Once operational, Maximum Power Point Tracking (MPPT) extracts peak power from the harvester while simultaneously tracking the transient nature of the source. In this low-power application, MCU programming needs to be efficient, while otherwise keeping the MCU in the lowest power standby mode possible to conserve energy. In a fully integrated design, a single MCU may be used for the sensor application, power management, power conversion, and MPPT functions.

Autonomous Flyback Converter for Energy Harvesting from Microbial Fuel Cells

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
F. Khaled ◽  
B. Allard ◽  
O. Ondel ◽  
C. Vollaire
Keyword(s):  
Fuel Cells ◽  
Energy Harvesting ◽  
Microbial Fuel Cells ◽  
Low Voltage ◽  
Maximum Power ◽  
Flyback Converter ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Start Up ◽  
Power Point

Cover letterAn autonomous flyback converter was designed for energy harvesting from Microbial Fuel Cells (MFCs). The circuit was optimized to minimize the losses and maximize the efficiency. A Maximum Power Point Tracking (MPPT) algorithm was implanted in the converter to extract the maximum power available from MFC. Discontinuous conduction mode operation of the flyback allows controlling the MPP operation by impedance matching. The flyback can start-up at low voltage, around 300 mV. The output open circuit voltage is about 20 V and the voltage at MPP is 6.4 V with a maximum efficiency of 71.2%.: Microbial fuel cells (MFCs) use bacteria as the catalysts to oxidize organic matter and generate electricity. This energy can be used to supply low power electronic systems. A power management unit between the MFCs and the load is required to adapt the voltage and control the operation. The low voltage and low power characteristics of MFCs prohibit the use of standard converter topologies since the threshold voltage of standard CMOS transistors in CMOS technology is higher than the output voltage of MFCs. A low-voltage start-up sub-circuit is required to charge a primary capacitor to supply the driver. A specific sub-circuit is also required to control the operation of MFCs for Maximum Power Point Tracking (MPPT) issues. An optimized Discontinuous Conduction Mode (DCM) autonomous flyback converter for energy harvesting is presented for ambient sources, like MFCs. The converter is designed, fabricated, and tested. An MPPT algorithm is integrated in the system to control the operation and to extract the maximum available power from the MFC. The converter is able of start and step-up MFC output voltage to a value higher than 3 V under load. The peak efficiency of the converter is 71.2%.

A Novel Interface Circuit with 99.2% MPPT Accuracy and 1.3% THD for Energy Harvesting

2017 ◽  
Vol 26 (11) ◽  
pp. 1750176 ◽  
Author(s):  
Yani Li ◽  
Zhangming Zhu ◽  
Yintang Yang ◽  
Yadong Sun ◽  
Xu Wang
Keyword(s):  
Energy Harvesting ◽  
Conversion Efficiency ◽  
Power Efficiency ◽  
Low Voltage ◽  
Harmonic Distortion ◽  
Cmos Process ◽  
Interface Circuit ◽  
Point Tracking ◽  
Peak Output Power ◽  
Power Point

To improve conversion efficiency and output quality of the energy harvester, a novel interface circuit with composite maximum power point tracking (MPPT) in energy harvesting applications is proposed in this paper. By using the ultra-low-voltage multiplier with digital control and simple one-cycle variable frequency technique, the converter realizes fast power tracking and high conversion efficiency, and minimizes the power consumption and harmonics, thereby obtaining high tracking precise and low total harmonic distortion (THD). Implemented in 65-nm CMOS process, this converter achieves 85.9% peak power efficiency with dc output voltage of 1.6[Formula: see text]V. The peak tracking efficiency and THD are 99.2% and 1.3%, respectively. The peak output power is 18.31[Formula: see text][Formula: see text]W, and the power loss of the entire converter is only 16.53[Formula: see text][Formula: see text]W.

ULTRA-LOW POWER BOOST CONVERTER WITH CONSTANT ON-TIME-BASED MPPT FOR ENERGY HARVESTING APPLICATIONS

2014 ◽  
Vol 23 (02) ◽  
pp. 1450027 ◽  
Author(s):  
MINGYANG CHEN ◽  
MENGLIAN ZHAO ◽  
QING LIU ◽  
LU WANG ◽  
XIAOBO WU
Keyword(s):  
Energy Harvesting ◽  
Low Power ◽  
Power Efficiency ◽  
Input Voltage ◽  
Boost Converter ◽  
Cmos Process ◽  
Ultra Low Power ◽  
Voltage Range ◽  
Point Tracking ◽  
Power Point

An ultra-low power boost converter for energy harvesting applications is introduced in this brief. The idle power dissipation is reduced to 800 nW by using a novel output voltage detector (OVD) which is insensitive to temperature variation and process deviation. Furthermore, a constant on-time (COT)-based hysteretic burst mode controller with maximum power point tracking (MPPT) technique is developed to ensure high power efficiency for a wide input voltage range. After startup, the input voltage can be set as low as 30 mV. The whole system is designed and fabricated in SMIC 0.18 μm CMOS process, the end-to-end power efficiency of this converter can reach 49% at 350 mV input voltage and 65% at 750 mV input voltage.

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