To improve the dynamic quality and control performance of the permanent magnet synchronous motor speed control system, a novel sliding mode control method with improved reaching law for PMSM was proposed, which has a shorter reaching time and small system chattering. An extended state observer (ESO) based on the hyperbolic tangent function for the sliding mode controller is designed to realize the real-time tracking of the mechanical angular velocity and load disturbance of the motor, which can weaken the influence of the internal parameter perturbation and external load disturbance. The performance of the novel sliding mode controller for PMSM was simulated based on MATLAB/Simulink. An experimental platform based on dSPACE is built. The simulation and experimental results show that this novel PMSM controller can effectively suppress the system chattering and improve the dynamic performance and robustness of the system.
A novel cylinder permanent magnet governor (CPMG) with Halbach segmentation is proposed in this paper. In order to improve the transmission performance of the CPMG, different permanent magnet (PM) arrangement methods are adopted. To achieve a fair comparison result, all the PMs are of the same size. The main magnetic fluxes are considered to obtain a comprehensive equivalent magnetic circuit model of the CPMG with Halbach array and analytical output torque that is calculated. The analytical method of transmitted torque for CPMG is then presented. Additionally, the effect of the average output torque of CPMG under parameters of the thickness of the copper rings, the slip rate and the effective coupling of the copper rings are investigated. Finally, the prototype platform is ready for testing on the field. The results were consistent with the results of the simulation, and the error was kept within the range of 5%. This research can provide a theoretical and practical reference for the optimal design of the transmission characteristic of CPMG.
To improve the performance and efficiency of ordinary galloping energy harvesters (GEHs), this paper proposes a GEH with a striped bluff body. The fluid-structure coupling simulation of the bluff body and the oscillator of the energy harvester was carried out using COMSOL Multiphysics. The cloud diagram in the flow field, tip displacement at the tip of the beam, lifting and dragging force, and trace and frequency response of the harvester are analyzed. Simulation results show that the GEH with a striped bluff body has the characteristics of rising frequency and falling peak compared with the ordinary GEH, which can be locked at a fixed peak to form a stable periodic response. Experimental results show that the striped bluff body energy harvester displays better energy harvest performance. The output root mean square voltage can be increased by 119.2% at 2 m/s wind speed, which means that the galloping harvester with a striped bluff body has more stable dynamic characteristics and shows better energy harvest performance.
In this paper, a piezoelectric energy harvester based on periodic one-dimensional acoustic black holes (ABH) is proposed to improve efficiency. The harvesting performance of the energy harvester with different ABH-structures was numerically simulated through the commercial software, COMSOL Multiphysics. Finally, an experimental platform was set up to test several energy harvester samples. The results show that the energy aggregation effect of the bilateral ABH beam is better than that of the traditional ABH beam. In the optimal impedance matching, the maximum output power of the energy harvester with bilateral ABH type 3 is 112 mW, which is 2.8 times that of the energy harvester with traditional ABH. The simulation and experimental results show that the energy harvesting efficiency of the proposed ABH is much higher than that of the energy harvester with traditional ABH. It is expected to make some contributions to the further development of lightweight wireless sensors, equipment service life, bearing fault diagnosis, and so on.
In recent years, energy harvesting technology has become a promising power supply method for low-power wireless sensor nodes. According to the application requirements of energy acquisition, a piezoelectric and electrostatic hybrid vibration energy harvester is proposed in this paper. Compared with other vibration energy harvesters, the proposed hybrid harvester is easier to miniaturize and integrate into a Micro-Electro-Mechanical System (MEMS). The electromechanical coupling model of the hybrid harvester is established. The optimal design of the proposed harvester is carried out based on numerical simulation. The optimal matching impedance of piezoelectric and electrostatic modules are calculated based on numerical simulation and validated through experiments, which are 80-90 kΩ and 15-20 MΩ, respectively. The output power of the hybrid vibration energy harvester is increased by 0.04%, 0.08%, 0.102%, and 0.097%, when the excitation acceleration is 0.1 g, 0.15 g, 0.2 g, and 0.25 g, respectively, compared with the single piezoelectric module.
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