A novel method of energy conversion and storage in Photoelectric Micro-power Supply

In wireless sensor nodes integrated with photoelectric micro-power supply, the efficiency of energy conversion and storage of Photoelectric Micro-power Supply (PMPS) determines their lifetime and adaptability to the environment. Therefore, it is important to improve the efficiency of the energy conversion and storage in the PMPS. However, traditional methods to improve the efficiency of the energy conversion and storage of the photovoltaic power system are not suitable in the PMPS due to the special requirement of wireless sensor nodes in the application. In this study, we propose a novel method to improve the efficiency of energy conversion and storage in the PMPS. In the method, the hybrid energy storage structure composed of super-capacitors and polymer lithium-ion batteries is used. The output power of solar cells is controlled by the circuitry of optimal voltage control. Likewise, Because of high-cycle and high-power density of super-capacitors, they are used as energy buffer. Polymer lithium-ion batteries are used as storage devices based on their high-energy density and low self-discharge rate. Polymer lithium-ion batteries are charged by super-capacitors under control of the circuitry of optimal voltage control. The mode of intermittent charge meets the requirement of rational charge of polymer lithium-ion batteries. Moreover, experiment results show the efficiency energy conversion and storage of the solar cells are improved nearly two times, compared with the method of direct energy storage.