## 5 Conclusions  
This paper presents a coaxial rotating non-contact coupling transducer structure based on the principles of electrostatic induction and magnetically actuated piezoelectric transduction. Although the absolute charge amount of the polar plates in the electret structure with alternating positive and negative polarities is reduced, it significantly enhances the charge variation amplitude and the charge difference between the electrodes. Consequently, the open-circuit voltage and short-circuit current of electret component are markedly increased. Additionally, the output electrical signal is less susceptible to interference, which is positively correlated with rotational speed and brief, making it more suitable than piezoelectric components for deriving rotational speed and wind speed information through \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Authors** & **Energy Harvesters** & **Output of Device** & **Key Features** \\ \hline [PERSON] et al. (2017) [18] & EEH of electret. & Reach 10.5 mW at 750 rpm, with 32 electrodes and 1500 V electrets. & Innovatively designed a rotational energy-harvesting structure with the same polarity electret. Based on research [18], further optimization of the device’s electrical performance is conducted. & Innovatively designed a rotational energy-harvesting structure with the same polarity electret. Based on research [18], further optimization of the device’s electrical performance is conducted. & Innovatively designed a rotational energy-harvesting structure with the same polarity electret. Based on research [18], further optimization of the device’s electrical performance is conducted. & Innovatively designed a rotational energy-harvesting structure with the same polarity electret. \\ [PERSON] et al. (2020) [19] & EEH of electret. & Reach 18.3 mW at 1000 rpm, 31\% higher than that of the previous design. & Based on research [18], further optimization of the device’s electrical performance is conducted. & Innovatively designed a rotational energy-harvesting structure with the same polarity electret. \\ [PERSON] et al. (2023) [20] & Integrated EMEH and TEH. & The output power of DC-TEH and EMEH reach 1.78 mW and 215 mW at 180 rpm. & Proposed DC-TEH integrated with EMEH to reduce losses caused by rectification and optimize output. & Proposed DC-TEH integrated harvester tailored to the specific requirements of designed C\({}_{2}\)H\({}_{2}\) sensor. \\ [PERSON] et al. (This study) & Integrated EEH and PEH. & Reach 6.74 mW at 700 rpm, with 16 electrodes and 600 V electrets. & Developed and optimized an electric- piezoelectric coupling structure, with advantages of non-contact and facilitating integrated measurement and supply. \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of the device based on a non-contact electret-piezoelectric coupling structure with other rotational energy-harvesting devices. inverse analysis. The magnetically actuated piezoelectric component, with an appropriately designed variable cross-section, exhibits a smaller stress distribution under load, resulting in a more stable structure. This design also changes the open-circuit voltage and natural frequency to optimize output performance and compensates for the low power density of the electrostatic components. The non-contact superposition coupling of multiple pairs of electret and piezoelectric transducers reliably enhances the absolute output of the device while providing complementary integration, broadening the operational frequency range, and optimizing performance at low rotational speeds. This design also extends the device's lifespan. By integrating the output characteristics of each component, an energy management circuit is designed, and the device is tested. It operates reliably within a rotational speed range of 100-700 rpm, achieving a maximum overall output power of 6.74 mW.