Applied Mechanics and Materials Vol. 150

Abstract: In this paper, we use recursive least squares method for magnetic single layer vibration isolation system identification to get the system transfer function matrix. By considering the fitting degree, pole-zero, the step response to adjust the order of model and noise structure for optimizing the model Identification. Applying the system transfer function matrix to the magnetic active vibration control system to improve the isolation effect. The results showed that: significantly improved isolation effect, verify the validity of this identification model for magnetic single isolation system.

Abstract: Digital control circuit for the hardware components, the impact of parameters on the control precision is analyzed. The digital control model is derived according to the requirements control of magnetic bearing system in this paper .Control accuracy and the prediction of control accuracy can be achieved by he theoretical estimates when numerical control system is given .For the future, it provides a simple and efficient method for estimating control accuracy of numerical controller.

Abstract: This paper attempts to analyze a comprehensive example of innovative design and NC machining. In this example, the designed works consists of three mechanical parts, which are designed in UG system. By the advanced CAM technology of UG, automatic programming is completed. But some NC programs are from manual programming. NC machining technology is used to process the works. The example involves integrated application of 3D modeling, NC processes and programming, and machining technology. The paper focuses on the processing method of the parts, in which the technical difficulties are analyzed and summarized. It can provide valuable reference for the research of NC machining technology.

Abstract: With the rapid development of intelligent power network, research on power station grounding has become a hot area in power system, as it can directly impact on the reliability of power system. The impact of substation grounding on short circuit current and on electric equipment is explored; Based on practical analysis, the relevant conclusion is reached in the end about the relation of neutral point grounding to the reliability of power network.

Abstract: PID controller is widely used in industry field, but when the industry presence exists noise interference, it is difficult for the conventional PID controller to achieve the expected control effect, in view of this situation, the method of combinating Kalman filter with the PID control is studied in this paper, the DC motor speed control system is simulated, the results shows that the PID controller based on Kalman filter is better to inhibit the effect of white noise, and it has a good dynamic response characteristics.

Abstract: In this paper, backstepping method is used to handle the nonlinear factors for magnetic bearing spindle systems, resulting in the design of a nonlinear robust controller to make the system in equilibrium with the global uniform asymptotic stability. Meanwhile, considering the uncertainty in the system model, the impact of uncertainty is introduced in the design process, so that the system has certain robustness. Simulation results show that this method can have a good control effect in the nonlinear magnetic bearing spindle applications..

Abstract: The switch power amplifier is widely used in magnetic bearing system, the lab uses pulse width modulator TL494 which is produced by U.S. Texas instruments company to drive power tubes. It can generate PWM signal. In this paper, a three level half bridge switch power amplifier is designed based on TL494.The original design of the double op-amp circuit is analyzed and improved through analyzing positive input signal for the internal error amp of TL494. Removing the redundant circuit, the new signal input circuit can realize the same function as the double op-amp circuit and the circuit structure can be more compact.

Abstract: To fulfil the objective of high speed, high precision and intelligence in the modern equipment and advanced manufacturing industry, the magnetic bearing is requested to have small volume, low cost and low consumption. In this paper, an AC-DC three-degree-of-freedom hybrid magnetic bearing (AC-DC-3DOF-HMB) is studied, which integrates radial bearing and axial bearing in one of the magnetic bearing. The configuration and principle of AC-DC-3DOF-HMB are expounded, and the mathematical models of suspension forces are given. Then based on the function block diagram of AC-DC-3DOF-HMB control system, its hardware and software configuration are designed. The experiment results show that the rotor can be suspended stably with three degrees of freedom and has a good performance in anti- interference, and the feasibility of the control system design can be verified.

Abstract: Wind power is a clean and renewable energy, and more and more countries in the world attach great importance to it and promote the development of the wind power industry. The current situation of wind turbines at home and abroad, the development, types, and characteristics were analyzed. The structural design of vertical axis wind turbine (VAWT) and aerodynamic theory of rotor blade were briefly introduced, the characteristic parameters in VAWT design were presented in this paper. Using finite element analysis method, the spindle which is the crucial component of VAWT under the extreme wind load was analyzed, and the corresponding results were obtained. Finally the wall thickness and the structure of spindle were improved and optimized to satisfy the engineering requirements of spindle.

Abstract: Currently, most domestic blower speed is still in 3000r/min level. The friction loss of mechanical bearings results in their low efficiency. To further improve the efficiency of the fan, a new high-speed maglev centrifugal fan was developed specially. The design of impeller styles, structure and size are rational. 3D graphics of the impeller and volute were drawn by using solidworks software. Application of CFD flow analysis software and the SIMPLE algorithm described viscous flow field within the three-dimensional centrifugal fan. By comparing simulation data with calculated data, optimize the turbine design. The simulative results are basically consistent with the design data, which provides a theoretical basis for the design of a new high-speed magnetic levitation fans, improving the level of centrifugal fan design.