Triple-MOSFETs switch for adaptive maximum capacitance point tracking of triboelectric nanogenerators

In recent years, triboelectric nanogenerator (TENG) has attracted much interest recently from academia and industry. In certain situations, TENG has great potential to replace battery. Nonetheless, in practical application, a special power management system (PMS) must be developed for TENG due to its characteristics of random amplitude, high voltage, and large internal resistance. The most critical factors in PMS are the design and control of the switch. The current studies have shown that there are two modes of energy transfer in the vibration process of a contact-separation TENG. The mode 1 refers to the discharge taking place immediately after the release of the two TENG surfaces, and the mode 2 refers to discharge right at the internal maximum capacitance point (MCP) of the TENG when the triboelectric surfaces come into contact. Studies have shown that, compared with the mode 1, the mode 2 can even have a 35% increasement in efficiency. However, due to irregularity of biomechanical motions of TENG, there is no switch can realize the tracking of MCP yet. This paper proposes a triple-MOSFETs switch (TMS) that only consists of three MOSFETs and one diode. Cooperating with the dual-output rectifier, the proposed TMS becomes the first switch to realize the tracking of MCP. Different from the current switches with fixed switch-on threshold, the proposed TMS has strong environmental adaptability and realizes MCP tracking in an extensive range of voltage, which greatly improves the energy transfer efficiency from TENG to load. The experimental results show that the energy transfer efficiency of the proposed switch is 43.28% higher than that of the fixed threshold switch. Compared to directly using TENG, employing the proposed switch increases the efficiency by a factor of 107.16. In the meantime, the response of the switch is very fast, and the discharging timing can be quickly adjusted according to the random vibration of TENG.