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20 mV Input, 4.2 V Output Boost Converter with
Methodology of Maximum Output Power for
Thermoelectric Energy Harvesting
Abstract:
This paper presents a low-input-voltage boost converter for
thermoelectric energy harvesting. In environments with 1-2 K thermal
difference, such as in the case of a body wearable application, TEG
generates several micro watts and tens of mV to the boost converter. For
the low-input-voltage operation, the power consumption of the control
circuit of the proposed boost converter is reduced by using a duty-cycle
bandgap reference voltage circuit. In order to maximizing the output
power, the input voltage of the boost converter is conventionally set to
half of an open voltage of a thermoelectric generator (TEG). In this
setting, however, conduction losses such as those of an inductor and a
power switch are not considered. The conventional boost converter cannot
output the maximum output power. We propose a methodology of the
maximum output power considering the conduction losses in the boost
converter. The boost converter was implemented in a 0.13μm CMOS
process. The output voltage can be boosted from 20 mV input which is
the open voltage of TEG of 1.5 Ω source resistance. The measurement
results show that the output power is increased by approximately 10%
using the proposed methodology for the open voltage between 20 mV and
100 mV
Existing System:
 For sensor ICs operating for a long time without maintenance,
development of a boost converter connected to a thermoelectric
generator (TEG) and a secondary battery such as a Li-ion battery is
underway.
 In environments with 1-2 K thermal difference, such as in the case
of a body-wearable application, TEG generates several micro watts
and tens of mV to the boost converter.
 Since the output power of the TEG is very small, power
consumption in a control circuit of the boost converter should be
reduced. Furthermore, the impedances of the boost converter and
the TEG should be matched so that maximum output power at the
boost converter is achieved.
Proposed system:
 In the proposed system by using conventional methodology, the
input voltage of the boost converter is set to half of an open voltage
of the TEG.
 In this setting, however, conduction losses such as those of an
inductor and a power switch are not considered. The conventional
boost converter cannot output the maximum output power.
 We propose a methodology to achieve the maximum output power
where the conduction losses in the boost converter are taken into
account.
Circuit diagram:
Reference:
[1] S.Lineykin and S. Ben-Yaakov, "Modeling and Analysis of
Thermoelectric Modules," IEEE Transactions on Industry Applications,
vol.43, no.2, pp.505-512, 2007. [2] J. Kim and C. Kim, "A DC–DC
Boost Converter with VariationTolerant MPPT Technique and Efficient
ZCS Circuit for Thermoelectric Energy Harvesting Applications," IEEE
Transactions on Power Electronics, vol.28, no.8, pp.3827-3833, 2013.
[3] Linear Technology, LTC 3108 datasheet, 2010,
http://cds.linear.com/docs/en/datasheet/3108fc. pdf. [4] Y. K. Ramadass
and A. P. Chandrakasan, "A Battery-Less Thermoelectric Energy
Harvesting Interface Circuit With 35 mV Startup Voltage," IEEE
Journal of Solid-State Circuits, vol.46, no.1, pp.333-341, 2011.