Mechanism, theory and application research of a rotating electromagnetic energy harvester suitable for multi-directional excitation

Energy harvesting in multi-directional excitation for human wearable devices is a challenge. A rotating electromagnetic energy harvester(REMEH) based on an eccentric rotor structure is proposed in this paper. Two poles of the magnets in REMEH are alternately arranged in a ring. The electrical output characteristics of the energy harvester are analyzed through theoretical, numerical simulation and experimental testing methods based on the establishment of magnetic flux density models, the coil induced voltage, and the excitation direction of the eccentric rotor structure. Theoretical analysis and experimental results show that the design of the eccentric rotor structure is well adapted to multi-directional and irregular excitation. The circular staggered arrangement of the magnets effectively increases the output voltage and output power. The results show that the average output power increases slowly when the walking speed increases from 1km/h to 3km/h, and the average output power increases substantially when the walking speed increases from 3km/h to 5km/h. When the walking speed is 1km/h and 3km/h, the average output power is 0.439mW and 0.638mW, respectively. At a walking speed of 5 km/h, the average output power increases rapidly to 1.68mW, corresponding to a power density of 16.59μW/g. This high-performance energy harvester can provide effective power supply for wearable devices or low-powered sensors.

Comprehensive Analysis On A New Type VR-Resolver with Toroidal Windings Under Healthy and Eccentric Cases

<div>A novel analysis for a new type Variable Reluctance Resolver (VR-Resolver) with toroidal windings is presented in this work. The resolver with various windings configurations as well as different rotor structures is considered for analysis. Position error of the resolvers in both healthy and eccentric cases are studied, where the effect of the eccentricity fault is analyzed for the resolvers with various windings configuration and rotor shapes. Hence, the analysis of the manufacturing tolerance due to the eccentric rotor is obtained by several analyses. Noticing the Magnetic Equivalent Circuit (MEC) method’s flexibility as well as in regards to the analysis of the several structures, a well-known flexible MEC-based method with adjustable accuracy is considered for modeling. Hence shorter processing time and more flexibility compared to Finite-Element-Method (FEM) are needed. Finally, the effectiveness of the presented works is proved by the performed validation via both FEM and experimental results.</div>

Comprehensive Analysis On A New Type VR-Resolver with Toroidal Windings Under Healthy and Eccentric Cases

<div>A novel analysis for a new type Variable Reluctance Resolver (VR-Resolver) with toroidal windings is presented in this work. The resolver with various windings configurations as well as different rotor structures is considered for analysis. Position error of the resolvers in both healthy and eccentric cases are studied, where the effect of the eccentricity fault is analyzed for the resolvers with various windings configuration and rotor shapes. Hence, the analysis of the manufacturing tolerance due to the eccentric rotor is obtained by several analyses. Noticing the Magnetic Equivalent Circuit (MEC) method’s flexibility as well as in regards to the analysis of the several structures, a well-known flexible MEC-based method with adjustable accuracy is considered for modeling. Hence shorter processing time and more flexibility compared to Finite-Element-Method (FEM) are needed. Finally, the effectiveness of the presented works is proved by the performed validation via both FEM and experimental results.</div>

Evaluating the Influence of Rotor-Casing Eccentricity on Turbine Efficiency Including Time-Resolved Flow Field Measurements

The clearance that exists between the casing and turbine blade tips is one of the key drivers of efficiency in gas turbine engines. For this reason, engine manufacturers utilize precise manufacturing techniques and may employ clearance control systems to minimize tip clearances to reduce associated losses. Despite these efforts, turbines typically exhibit some nominal casing ovality or rotor-casing eccentricity, and changes to blade tip clearance during operation commonly occur due to thermal and mechanical stresses. The present study investigates non-axisymmetric tip clearance effects by creating a rotor-casing eccentricity in a one-stage axial test turbine operating in a continuous-duration mode at engine relevant conditions with engine representative hardware. A magnetic levitation bearing system was leveraged to move the turbine shaft to vary the rotor-casing eccentricity without test section disassembly. The results of this study indicate that rotor-casing eccentricity does not affect overall turbine efficiency over the range that was tested, but does locally influence efficiency and the rotor exit flow field. Comparisons of flow angle and secondary flow kinetic energy agreed with previous studies and existing analytical methods, respectively. Collectively, these results indicate that tip clearance can be studied locally on an eccentric rotor.

Evaluating the Influence of Rotor-Casing Eccentricity on Turbine Efficiency Including Time-Resolved Flow Field Measurements

The clearance that exists between the casing and turbine blade tips is one of the key drivers of efficiency in gas turbine engines. For this reason, engine manufacturers utilize precise manufacturing techniques and may employ clearance control systems to minimize tip clearances to reduce associated losses. Despite these efforts, turbines typically exhibit some nominal casing ovality or rotor-casing eccentricity, and changes to blade tip clearance during operation commonly occur due to thermal and mechanical stresses. The present study investigates non-axisymmetric tip clearance effects by creating a rotor-casing eccentricity in a one-stage axial test turbine operating in a continuous-duration mode at engine relevant conditions with engine representative hardware. A magnetic levitation bearing system was leveraged to move the turbine shaft to vary the rotor-casing eccentricity without test section disassembly. The results of this study indicate that rotor-casing eccentricity does not affect overall turbine efficiency over the range that was tested, but does locally influence efficiency and the rotor exit flow field. Comparisons of flow angle and secondary flow kinetic energy agreed with previous studies and existing analytical methods, respectively. Collectively, these results indicate that tip clearance can be studied locally on an eccentric rotor.

Recent Advances in Elongational Flow Dominated Polymer Processing Technologies

The continuous development of plasticizing conveying methods and devices has been carried out to meet the needs of the polymer processing industry. As compared to the conventional shear-flow-dominated plasticizing and conveying techniques, a new method for processing polymers based on elongational flow was proposed. This new method and the related devices such as vane extruders, eccentric rotor extruders and so on, exhibited multiple advantages including shorter processing time, higher mixing effectiveness, improved product performance and better adaptability to various material systems. The development of new techniques in the field of polymer material processing has opened up a broad space for the development of new plastic products, improved product performance and reduced processing costs. In this review, recent advances concerning the processing techniques based on elongational flow are summarized, and the broad applications in polymer processing as well as some future opportunities and challenges in this vibrant area are elucidated in detail.

Testing and Analysis Fault of Induction Motor for Case Study Misalignment Installation Using Current Signal with Energy Coefficient

An induction motor is a key device for an industrial machine. The installation misalignment of the motor will result in derating problems and energy consumption that is generally used to analyze signal faults using the fast Fourier transform (FFT) method. Problems with the rotor affect the non-stationary signal and FFT can be utilized to analyze this problem inefficiently. This paper proposed the testing and analysis of faults in an eccentric rotor at different levels using the stator current detection technique and the calculation of the energy signal coefficient via the wavelet decomposition (WD) method. The experimental results showed that an increase in eccentricity had a linear relation with the energy signal, where R2 was 80.81%. Moreover, the test results illustrated that the proposed method was more efficient than FFT and applicable to motor fault analysis and application in the industrial.

Theory of Frequency Captured of Eccentric Rotor by Vibration Environment with Same Direction

Aiming at the frequency synchronization phenomena of oscillating or rotating bodies, this paper proposes a novel solution to address the self-synchronization problem of vibration systems. An integral mean method with small parameters and periodic coefficient (IMM-SPPC) is proposed, which converts the relative motion of the electrically driven eccentric rotor and the vibration environment into a second-order periodic coefficient differential equation. Through the calculation of the equilibrium point of the second-order periodic coefficient differential equation and the study of its stability, the synchronization criterion and the stability criterion of the eccentric rotor and the vibration environment are deduced. The simulation results show the validity of the deduced synchronization criterion and stability criterion. The proposed IMM-SPPC provides a new way for studying vibration synchronization.