Signal Conditioning Circuit for Energy Harvesters

Srikanta S, Dr. K. P. Lakshmi

Abstract: In today's fast-paced world of science and technology, efficient utilization of energy resources is vital to address rising global demands while fostering sustainable development. Rapid industrialization and societal advancements have significantly increased energy consumption, driving the need for innovative solutions to harness unused energy from the environment. This work focuses on investigating, designing, and implementing methods to capture dissipated energy from electronic devices and industrial machinery, converting waste heat into usable electricity. The study highlights a signal conditioning circuit developed to harvest renewable energy in the form of heat, primarily from sources like server rooms, electronic devices, or industrial machinery where substantial heat is dissipated. The circuit features a resistive Wheatstone bridge in a balanced state, with one arm comprising a PT100 sensor. Temperature variations cause the bridge to become unbalanced, generating a small, low- amplitude, and noisy signal. To process this signal, an AD620 instrumentation amplifier is used, which amplifies it, reduces noise, and provides enhanced common-mode rejection and filtering capabilities. The AD620 module amplifies the signal to approximately 0.9V, sufficient to charge a 1V rechargeable cell. Additionally, an MCP1640 circuit boosts the voltage to a stable 3.3V DC. For battery safety, an MCP73831 IC acts as a charge controller, complemented by a PCM module for overcurrent and surge protection, ensuring secure storage in a rechargeable battery.

Keywords: energy harvesting, waste heat recovery, signal conditioning, renewable energy circuits, thermal to electrical conversion