Motor Noise and Vibration Test Research

Some factors, such as friction, vibration, and so on, can result in the fault and abnormal noise in the motor. Based on the detection and analysis of noise and vibration, we can identify and eliminate the faults of the motor. This is helpful not only to ensure the completion of production tasks, but also to prevent accidents. In this paper, we briefly introduce the motor noise generation principle. A laptop computer and LabVIEW software are used to design the experiment system to detect and analysis the noise and vibration of motor. External microphone and computer with sound card constitute noise detection system hardware. Vibration sensor and the data acquisition card constitute vibration detection system hardware. LabVIEW software combined with FFT analysis is used to realize the noise signal acquisition, recording and spectral analysis. Detecting and analyzing the noise of the permanent magnet DC motor and three-phase asynchronous motor proves that the motor noise and vibration detecting experimental platform is fully meet the requirements of motor test and research. This detection and analysis system has a good man-machine interface and strong operability

Numerical Investigation of Storage Behaviors of A Liquid CO2 Tank

The dynamic behavior of heat transfer induced by flow of the storage tank during the storage process was investigated using the computational fluid dynamics (CFD) approach, with the target of the liquid CO2 storage tank in a CO2 injection station in an oilfield. The flow field distribution outside the tank was simulated, exhibiting the patterns of air flow near the tank wall. The effect of progressive cooling leakage in the tank under various conditions was determined through simulation of the dynamic of flow heat transfer under various storage settings, with the result indicating that tank pressure has a beneficial effect on cooling capacity. The medium level, on the other hand, had a negative impact on cooling capacity. Finally, the impact of environmental variables on fluid loss was evaluated. This finding supports the safety and cost-benefit analysis of liquid CO2 storage systems

Research on bi-directional four-port converter of solar electric vehicle

Existing electric vehicles are mainly powered by batteries, which have short driving miles, inconvenient charging, still a large proportion of charging electricity from fossil-fuel power plant, and still not solving the pollution problem from the source and other defects. Connecting solar power to electric vehicles to form a complex energy system can help solve these problems. A bi-directional four port converter consisting of one BOOST and three SEPIC/ZETA circuits is presented to control the composite energy system consisting of photovoltaic panels, battery and super capacitor. BOOST circuit enables maximum power tracking of the solar panels and delivers energy to the DC bus. The first bi-directional SEPIC/ZETA circuit enables the bi-directional flow of energy between the battery and the DC bus during discharge and charging. The second bi-directional SEPIC/ZETA circuit enables the bi-directional flow of energy between the super capacitor and the DC bus during discharge and charging. The third bi-directional SEPIC/ZETA circuit converts the DC bus voltage to a suitable load voltage or feeds the load braking energy back to the DC bus. The bi-directional four-port converter enables multiple modes of operation for complex energy systems, such as maximum power tracking of the photovoltaic panel, battery power to the load, high power density output from the super capacitor, return of braking energy from the load, power supply from the photovoltaic panel to the load, and charging of the photovoltaic panel to the battery and super capacitor, and so on. Simulations and experiments demonstrate that the proposed bi-directional four-port converter can manage multiple operating modes of the complex energy system well and ensure the stability of voltage and power during mode switching. It also proves that the addition of solar energy can effectively reduce the consumption of battery energy, thus improving the driving miles and battery life and contributing to the pure green operation of electric vehicles

Research on the rapid calculation method of temperature rise of cable core of duct cable under emergency load

In order to facilitate engineers to manage dynamic loads in real time and improve the utilization of power cables, it is necessary to accurately calculate the temperature rise of cable cores under duct laying conditions. The transient thermal circuit model involved in this paper helps to improve the speed of dynamic response and the accuracy of transient temperature rise calculation for power cable cores under duct laying conditions. Since the impact of the environmental conditions, exploring the computational relationships of the thermal circuit model parameters helps to improve the engineering applicability of the model. The duct cable can be broken down into three parts: the cable body, the air inside the pipe and the external environment. In engineering, the thermal circuit model parameters of the cable body can be made into a table and applied by looking up the table. The thermal circuit model parameters of air in duct are related to the cable outside diameter and duct inside diameter, and can also be engineered using tables for application. The fit gives the third part of the equation with respect to the thermal resistance coefficient of the duct and soil and the burial depth. The error in applying the decentralized thermal circuit model and parametric expressions is less than 1 °C compared to the results of finite element calculations. This proves that the decomposition of the duct power cable model improves the accuracy of the transient temperature rise calculation. The relationship equation between the parameters of the thermal circuit model and the laying conditions helps to improve the engineering adaptability of the method

A novel transient thermal circuit model of buried power cables for emergency and dynamic load

In order to improve the utilization rate of cable while ensuring safety and reliability, accurate and rapid evaluation of transient temperature rise of directly buried power cables is useful to improve the management level of dynamic capacity increase and emergency load conditions. Since the existing thermal circuit model is relatively complex or not very accurate, an equivalent three-branch transient thermal circuit model is presented for the complex cable structure and heat dissipation environment based on the uniqueness of the temperature field. Considering the electric circuit similarity, the transient analysis method of the centralized parameter network in the circuit is used to establish the transient adjoint model of the thermal capacity branch, provide the node conduction matrix of the transient thermal circuit model, and write the node temperature rise equation as a function of the node heat flow. By comparing the solution of the thermal circuit model with the finite element results, and the genetic algorithm is used to optimize and obtain the equivalent thermal resistance and thermal capacity parameters of the transient thermal circuit model. The comparison of finite element calculation results proves that the proposed three-branch transient thermal circuit model is more accurate than the two-branch thermal circuit model. Compared to the traditional all-part thermal circuit model, the three-branch model can be rapidly solved and easily applied in engineering

The Existence of Positive Solutions for a Fourth-Order Difference Equation with Sum Form Boundary Conditions

We consider the fourth-order difference equation: Δ(z(k+1)Δ3u(k-1))=w(k)f(k,u(k)),  k∈{1,2,…,n-1} subject to the boundary conditions: u(0)=u(n+2)=∑i=1n+1g(i)u(i), aΔ2u(0)-bz(2)Δ3u(0)=∑i=3n+1h(i)Δ2u(i-2), aΔ2u(n)-bz(n+1)Δ3u(n-1)=∑i=3n+1h(i)Δ2u(i-2), where a,b>0 and Δu(k)=u(k+1)-u(k) for k∈{0,1,…,n-1},  f:{0,1,…,n}×[0,+∞)→[0,+∞) is continuous. h(i) is nonnegative i∈{2,3,…,n+2}; g(i) is nonnegative for i∈{0,1,…,n}. Using fixed point theorem of cone expansion and compression of norm type and Hölder’s inequality, various existence, multiplicity, and nonexistence results of positive solutions for above problem are derived, which extends and improves some known recent results

Electromagnetic simulations of a fully superconducting 10-MW-Class wind turbine generator

An electromagnetic design study of a 10-MW-class synchronous generator that has both the field and armature windings superconducting is presented. The field winding is assumed to be made of YBCO tapes, whereas multifilament MgB2 wires are considered for the armature winding. The proposed design is analyzed using a finite-element-based simulation tool. The results obtained show that a higher output voltage, and hence higher power levels, can be achieved compared with the more common arrangement where the field winding is superconducting whereas the armature winding is made of copper. Moreover, the proposed structure weighs less and has better flux density distribution within the armatur