Research On Distributed Thermoelectric Power Generation System

As an environment-friendly energy alternative, the thermoelectric generator(TEG) has attracted considerable interest due to its zero pollution, low noise, long life and cleanness of energy production. It converts thermal energy directly into electricity, and has a wide prospect in the applications such as industrial waste heat recovery, vehicle exhaust gas and deep space missions. In this paper, the maximum power point tracking method(MPPT), distributed TEG system architecture, control strategy and implementation are investigated to improve the energy efficiency of the system.The basic thermoelectric effect of the TEG is analyzed and the equivalent circuit model of TEG module is obtained, with the output characteristics tested. The analysis and experimental results show that a TEG module can be equivalent to a dc source and a resistor connected in series, and its internal resistance, open-circuit voltage, voltage and power of the maximum power point are affected by the temperature. According to the maximum power transmitting theorem, a MPPT method based on resistance matching is researched, which means matching the input impedance of the converter with the internal resistance, and the maximization of the output power of the TEG module is realized.When the TEG modules are connected in series, MPPT of each module can’t be ensured in the centralized TEG power system, due to the difference of output characteristics of TEG modules and unevenly distributed heat flux and energy. To solve the problem, two distributed TEG system architectures, module-module type differential power processing based on bidirectional Buck/Boost converters and module-output type differential power processing based on unidirectional Flyback converters, are studied in this paper. The system structure, working principle and power transmission characteristics of the two distributed TEG systems are analyzed in detail, and the optimized control strategy has been given. The experimental results based on four TEG modules show that the two systems can achieve the distributed MPPT under various conditions. Compared to the traditional centralized TEG power system, the two distributed systems researched in this paper can generated more power, which indicate the validity of the power control. Furthermore, both the theoretical and experimental results demonstrate that the module-output type system is more suitable for applications where the temperature differences of TEG modules are unevenly distributed and change frequently, while the module-module type is preferred for the situations with stable temperature differences.