DC-DC converter suitable for thermoelectric generator

With recent advancements in thermoelectric material performance, thermoelectric generators have become a viable alternative for power generation using small temperature differentials with benefits that can not be found in other energy conversion methods. The power generated by a thermoelectric generator, using a small ΔT, is characterized by a relatively high current (-∼5 A), but a relatively low voltage (<0.3 V), which is often not suited for many practical applications. In order to make use of the thermoelectric generated power in applications requiring a higher voltage, a DC-DC step up converter that can handle low input voltage is needed. Commercial available DC step up converters require an input voltage of at least 0.7 volts, which is the minimal voltage required for operating a bipolar junction switch. Several novel approaches for low input voltage DC-DC converter concepts have been studied and proved to be feasible. Their operations are based on some unconventional methods achieving DC to AC conversion for low input voltage. In one solid state approach, a normally-on transistor and a tunnel diode were utilized to achieve low voltage oscillation. A conversion concept was also developed which is based on an electromagnetic actuated mechanical switch. Operating principles and measured performance of these approaches will be reported.