This work develops an integrated thermoelectric energy-harvesting system for low-grade waste heat. Because a thermoelectric generator (TEG) operating at a small temperature difference (approximately 15 K) produces a low voltage (below 100 mV), the system requires a DC–DC converter capable of self-starting at low input voltage while drawing substantial current. Several transformer-based startup oscillators are modeled and optimized, leading to a novel autotransformer-based common-drain oscillator that generates the pulses needed to start the boost converter directly from the TEG. The transformer-based converter provides a high voltage conversion ratio, low input impedance, and high output power. A gain-controlled oscillator enables manual maximum power point tracking (MPPT), while digital control supports MPPT with fewer components and reduced voltage sampling. An energy-management system regulates the output voltage and stores surplus energy. Finally, a TEG module fabricated from in-house-synthesized n-type Ag₂Se and p-type MgAgSb is characterized and demonstrated together with the converter for low-grade waste-heat harvesting.
