Abstarct: Thermoelectric generator (TEG) systems are used to produce electric power in many situations. They are noiseless, environmentally friendly, cheap and without moving parts. The performance of TEG depends on the temperature difference between the two sides of the module, so it is necessary to provide suitable working conditions to obtain maximum efficiency. TEG systems are often in unstable thermal boundary conditions. Therefore, thermal management of the system is necessary to improve electrical performance. In this study, phase change materials (PCMs) were used due to their inherent properties in latent thermal energy storage, on the hot and cold side of the module, inside aluminum tanks with thin walls. On the other hand, these materials have high thermal resistance, which increase the energy storage time. In order to increase the thermal conductivity and to accelerate the heat transfer mechanism, copper and nickel mextal foams were used in the PCM. In the experiments, an electrical heater was used as a representative of the heat source to apply heat to the system and create unstable boundary conditions with constant and fluctuating thermal loads, and thermocouples at different points of the box measured the temperature of different points at every moment. In addition, a data logger recorded temperatures and voltage at different times. The results of using the mentioned materials in the TEG system and on the hot side of the module showed that the temperature of the hot side was controlled and the module was protected against the thermal fluctuations of the heat source and sudden temperature increase. The potential of PCM in absorbing and releasing thermal energy led to the storage of a significant amount of energy. The foam inside the PCM decreased its thermal resistance and increased the thermal capacity. When the heater is on, the PCM temperature increases and leads to a decrease in the temperature of the box body and the hot side, resulting in a decrease in the temperature of the cold side and an improvement in its voltage. After the heater was turned off, the thermal energy was transferred from the PCM to the foam and then to the hot side at a faster rate, and the system was more suitable in generating voltage due to the higher temperature of the hot side. Due to temperature control on both sides of the module, the system including copper foam provided higher electrical strength than nickel. The results of tests on the cold side showed that the use of copper foam in PCM as a heat sink is a suitable alternative to the electrical fan and is the key factor for a TEG system with zero cooling energy. This system led to control the temperature of the cold and hot sides of the module and improve the production voltage.