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Interest in autonomous low-power energy sources has risen with the development and widespread use of devices with very low energy consumption. Interest in thermoelectric harvesters has increased against this background. Thermoelectric harvesters, especially harvesters on-chip, have peculiar properties related to the thermal route, thermal transients, and spatial temperature distribution within the chip. A behavioral model of the harvester is required for engineers to successfully develop voltage converters with maximum power point tracking and energy storage units. There are accurate models based on the finite element method, but these models are usually not compatible with simulators of electrical circuits, and therefore are not convenient for designers. Existing equivalent circuit models fit this requirement, but usually do not consider many parameters. This article proposes an original method that allows simulating spatial thermoelectric processes by analogy with the finite difference method, using electrical circuits simulations software. The study proposes a complete methodology for building the model and examples of simulations of one-, two- and three-dimensional problems, as well as examples of simulation of macro problems in the presence of external thermal and electrical devices, such as heatsink and electrical load.

The brief presents some principles of the ON/OFF operational strategy applied to energy management of a hybrid internal combustion engine (ICE) based auxiliary power unit (APU). It is shown that significant reduction of fuel consumption (78% for the example system presented) and maintenance expenses (80% operation time decrease was attained by the system) may be achieved by such a strategy, shifting the system operation point towards corresponding optimal region. The side effect of aggravated amount of starting events is cured by employing an actively balanced supercapacitor (SC)-based emergency starter (SCS). The SCS operates as short-time energy storage device, charging from the battery at a low rate and then providing a current burst required for proper internal combustion engine starting. Current sensorless method of automatic connection (based on bus voltage sensing) and disconnection (based on sensing the voltage across bidirectional MOSFET-based switch) of the SCS is also proposed. The proposed circuitry, successfully validated by experiments, may be arbitrarily scaled up or down according to application rating., Competing Interests: The authors declare no conflict of interest.