Energy management strategy to simplify the hardware structure of wireless sensor nodes

Abstract

Maximum power point tracking (MPPT) circuits in photovoltaic (PV) cell-based wireless sensor nodes often make the systems complex and costly. This paper proposes a novel energy management strategy for PV cell-based systems to remove their MPPT circuit without reducing their working efficiency. By modeling the non-MPPT system, energy storage in different situations is calculated. The key factors to improve the working efficiency of the system, such as operating voltage and number of PV cells in series, are also analyzed. A design is proposed to maximize the working efficiency. Another model for systems including MPPT circuits is also proposed for comparison. Simulation analysis shows that during the monitoring period, the total active time of the non-MPPT system can be as long as that of the system with MPPT circuits. Experimental tests confirm the validity of the proposed energy strategy. More importantly, the number of electronic components in the non-MPPT system’s power module is only approximately 1/5 of that of the other system. This strategy provides a possible approach for practical wireless sensor nodes that are small in size and have low cost.