A new cycle model of a two-stage combined semiconductor thermoelectric device that is used as a heat pump is established. The influence of Joule heating due to the electric current and heat leak due to the temperature difference between the hot and the cold junctions on the performance of the system is investigated. The general expressions of three important performance parameters, the coefficient of performance (COP), the rate of heat pumping and the power input, are derived. The maximum COP and the corresponding parameters are calculated. The internal structure parameter

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A hybrid system consisting of a solid oxide fuel cell, a semiconductor thermoelectric generator and a regenerator is put forward. Expressions for the efficiencies and power outputs of the fuel cell, thermoelectric generator and hybrid system are derived. The relation between the electric currents in the fuel cell and thermoelectric generator is revealed. The maximum efficiency and power output of the hybrid system are calculated numerically. The optimally operating electric currents in the fuel cell and thermoelectric generator are calculated and consequently the optimal region of the hybrid system is determined. The results obtained here will provide some guidance for further understanding the performance and operation of practical fuel cell–thermoelectric generator hybrid systems.

A half-bridge circuit topology for driving high-intensity discharge lamps at high frequencies is proposed. The high-frequency square wave is modulated synchronously by low-frequency, sawtooth signals. Under such circumstances, the phenomenon of acoustic resonance can be successfully prevented because standing waves within the wall of the lamp are eliminated. This has been experimentally verified. Results obtained will offer useful information for designing high-efficiency high-intensity discharge lamps.

A digital circuit for driving a low-frequency, small-wattage, high-intensity discharge lamp is proposed. By combining a digital potentiometer X9313 and a microcontroller STM32F103, the lamp can be turned on and off automatically according to the operating condition. The lamp power can be altered flexibly based on the needed luminance because it is designed to be a linear function of the resistance of the potentiometer X9313. The lighting system has an electrical efficiency of 88% and can save more than 20% of energy, compared with a traditional lamp. A remote desktop client on Android is developed for the purpose of wireless and convenient control. The proposed model will provide important information for designing high-performance, low-frequency, small-wattage, high-intensity discharge lamps.

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