To realize the self-power of the vehicle micro-sensors, a piezo-electromagnetic hybrid vehicle-mounted energy harvester is proposed to recover the wind and vibration energy generated during driving. This energy harvester includes a flutter piezoelectric energy harvesting structure (FPEH) and an electromagnetic vibration energy harvester structure (EVEH). The combination of the two structures can improve the energy harvesting effect and reduce the cut-in wind speed. The coupled vibration mathematical model is established to predict the output performance of the wind energy harvesting effect. The effects of the different distances between magnets on the output are discussed. And the vibration characteristics of piezoelectric and electromagnetic vibrators are analyzed. Results show that the energy-harvesting effect is the best when the distance between magnets is 30mm. At the same time, the numerical simulation proves that the wind energy harvesting effect of the hybrid structure is better than the classic flutter structure. The experimental verification is carried out, and the experimental results are consistent with the theoretical prediction results, which verified the correctness of the theory. The optimal load of FPEH is 70kΩ , and the optimal load of EVEH is 60Ω. Under these conditions, when the wind speed is 18m/s, the peak output power of FPEH is 14.5mW, and that of EVEH is 31.8mW.

Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide sufficiently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using experimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM.

To meet the needs of low-power microelectronic devices for on-site self-supply energy, a galloping piezoelectric–electromagnetic energy harvester (GPEEH) is proposed. It consists of a galloping piezoelectric energy harvester (GPEH) and an electromagnetic energy harvester (EEH), which is installed inside the bluff body of the GPEH. The vibration at the end of the GPEH cantilever drives the magnet to vibrate, so that electromagnetic energy can be captured by cutting off the induced magnetic field lines. The coupling structure is a two-degree-of-freedom motion, which improves the output power of the energy harvester. Based on Hamilton’s variational principle and quasi-static hypothesis, the piezoelectric–electromagnetic vibrated coupling equation is established, and the output characteristics of GPEEH are obtained by the method of numerical simulation. Using the method of numerical simulation, studies a series of parameters on the output performance. when the wind speed is 9 m/s, the effective output power of the GPEEH is compared with the classical galloping piezoelectric energy harvester (CGPEH) who is no magnet. It is found that the output power of GPEEH 121% higher than the output power of CGPEH. Finally, set up an experimental platform, and test and verify. The experimental analysis results show that the simulated output parameter curves are basically consistent with the experimental drawing curves. In addition, when the wind speed is 9 m/s, under the same parameters, the effective output power of the GPEEH is 112.5% higher than that of the CGPEH. The correctness of the model is verified.

In order to study the influence of vehicle body vibration caused by road excitation on the output performance of a vehicle piezoelectric electromagnetic hybrid energy harvester, the theoretical analysis of the energy harvester is carried out, and a corresponding electromechanical coupling model is established. The hybrid energy harvester includes a flutter piezoelectric energy harvester (FPEH) and an electromagnetic vibration energy harvester (EVEH). Sweep frequency experiments and wind tunnel experiments were carried out to verify the correctness of the coupling model. By establishing the road-vehicle coupling differential equations solving module, the vehicle body vibration under different road surfaces was simulated, and the influence of different roads on output performance is analyzed. The results show that when vehicle body vibration is not considered, the cut-in speed of the harvester is 32 km h⁻¹. When the vehicle speed is higher than 32 km h⁻¹, vehicle body vibration caused by road roughness will suppress the overall output performance. When the vehicle speed is less than 32 km h⁻¹, the vibration of the vehicle body will cause the energy harvester to have no obvious cut-in wind speed. And the higher the road level, the stronger the body vibration, and the better the output performance when the vehicle speed is less than 32 km h⁻¹. Under E-class road with vehicle body vibration considered, it has already power output at a vehicle speed of 20 km h⁻¹. When the vehicle speed reaches 57 km h⁻¹, the output power of hybrid FPEH and EVEH reach 1.74 and 2.51 mW under E-class road (2.88 and 3.25 mW under A-class road), respectively.