Prediction of Static Characteristic Parameters of an Insulated Gate Bipolar Transistor Using Artificial Neural Network

Breakdown voltage (BV), on-state voltage (Von), static latch-up voltage (Vlu), static latch-up current density (Jlu), and threshold voltage (Vth), etc., are critical static characteristic parameters of an IGBT for researchers. Von and Vth can characterize the conduction capability of the device, while BV, Vlu, and Jlu can help designers analyze the safe operating area (SOA) of the device and its reliability. In this paper, we propose a multi-layer artificial neural network (ANN) framework to predict these characteristic parameters. The proposed scheme can accurately fit the relationship between structural parameters and static characteristic parameters. Given the structural parameters of the device, characteristic parameters can be generated accurately and efficiently. Compared with technology computer-aided design (TCAD) simulation, the average errors of our scheme for each characteristic parameter are within 8%, especially for BV and Vth, while the errors are controlled within 1%, and the evaluation speed is improved more than 107 times. In addition, since the prediction process is mathematically a matrix operation process, there is no convergence problem, which there is in a TCAD simulation.

Estimation of the Accuracy of a Control System with a Fuzzy PID Controller Based on the Approximation of the Static Characteristic of the Controller

The problem of estimating the accuracy of an automatic control system with a fuzzy PID controller is solved. To describe a fuzzy controller, its static characteristic is used, which is approximated by two piecewise-linear and one piecewise-constant sections. This approach makes it possible to study the system as a linear one at each section of the approximated characteristic, and accordingly develop the calculation methods known in control engineering, taking into account the features of the system under consideration. In the article, to calculate the error in the steady state, the theorem on the final value of the original is used. For two different types of second-order control objects — static and astatic — on the basis of this theorem, analytical expressions are obtained that relate the accuracy of the control system with the values of the target and disturbance with a different structure of the controller (P-, PI-, PD-). When conducting experimental studies, the fuzzy PID controller was compared with a linear one tuned by the method of the maximum stability. Research results show that a fuzzy controller ensures the accuracy of the control system is not worse than a linear one, while increasing the dynamics of the system. The analytical expressions presented in the article make it possible to assess the accuracy of a control system with a fuzzy controller and can be used as a technique for adjusting the controller based on the accuracy requirements.

Steady State Thermal Effect on Static Characteristic of Copper Roller Shaft

The static analysis of a copper roller shaft is performed. The copper roller shaft consists of bushing, pen roll and roller. All of those components g4bconsist of different materials. Thermal steady state and statical analysis is performed in order to investigate the thermal effect of high temperature copper slab on the roller shaft. The copper slab temperature is 1200 OC. Based on this work obtained that the maximum total deformation is 0.0050523 m, maximum equivalent stress is 41600 MPa, maximum life cycle is 1011, total heat flux maximum is 879910 W/m2 and the maximum damage occur in the pen roll component.

Correction of the static characteristic of a frequency converter to reduce the amplitudes of resonance vibrations of the vibrating table

It is known that vibration systems of directional vibrations based on asynchronous vibration motors are currently widely used in practice, but at the same time they have a significant drawback - a sharp increase in vibration amplitudes when passing through the resonance zone at the time of acceleration and deceleration of vibration motors, which negatively affects their operation. The article discusses a vibration table with two unbalanced asynchronous vibration motors. The calculation scheme and equations of motion of such a vibration system are presented. It is shown that the vibration table as a control object is an oscillatory link with a pronounced resonant frequency. The equations of motion of asynchronous vibration motors with scalar frequency control are given. A structural diagram of a vibration table with unbalanced exciters has been developed, the modeling of which made it possible to determine the amplitudes of resonant oscillations. It is proposed to apply correction of the static characteristics of the frequency converter, which connects the effective value of the output voltage with the frequency, to reduce the resonance amplitudes. Equations of the desired static characteristics of the inverter and analytical dependences for calculating the necessary coefficients for its implementation are given. A computational model has been developed that makes it possible to take into account the effect of the corrected static characteristic of the frequency converter on the operation of the vibrating table at the stages of acceleration and deceleration. The results of computer simulation are given, convincingly showing that the correction of the static characteristics of the inverter is an effective means of reducing the amplitudes of resonant oscillations. It is shown that modern frequency converters have functionality that makes it easy to correct the dependence of the effective value of the output voltage on the frequency. The need to adjust the static characteristics of the inverter for a specific type of product tested on the vibration table is noted.

Finite element model for static characteristic analysis of rolling linear guide

From the designer’s point of view, the static precise finite element model of the single ball-raceway, the overall and the unit slice of the rolling linear guide (RLG) are established based on the limited data obtained. According to the contact characteristics of a single ball-raceway, Hertz theory and finite element method (FEM) are used to determine the maximum contact stress and deformation of RLG under a specific preload value. The specific modeling process of the overall and unit slice finite element model of the RLG is described in detail as well. The comparative analysis results indicate that the unit slice finite element model can take place of the overall finite element model at the static level. On the basis of previous research, the mapping laws between external load, preload value, curvature ratio, the carriage’s wall thickness, the guide’s width, and static mechanical properties of RLG are studied. The combined application of these precise finite element models can solve the problems of large calculation and low efficiency in statics of RLG. Meanwhile, it also provides a new way to achieve high-efficiency and high-rigidity design of RLG from the source.

Double Closed-Loop Compound Control Strategy for Magnetic Liquid Double Suspension Bearing

As a new type of suspension bearing, the magnetic liquid double suspension bearing (MLDSB) is mainly supported by electromagnetic suspension and supplemented by hydrostatic support. At present, the MLDSB adopts the regulation strategy of “electromagnetic-position feedback closed-loop, hydrostatic constant-flow supply” (referred to as CFC mode). In the equilibrium position, the external load is carried by the electromagnetic system, and the hydrostatic system produces no supporting force. Thus, the carrying capacity and supporting stiffness of the MLDSB can be reduced. To solve this problem, the double closed-loop control strategy of “electromagnetic system-force feedback inner loop and hydrostatic-position feedback outer loop” (referred to as DCL mode) was proposed to improve the bearing performance and operation stability of the MLDSB. First, the mathematical models of CFC mode and DCL mode of the single DOF supporting system were established. Second, the real-time variation laws of rotor displacement, flow/hydrostatic force, and regulating current/electromagnetic force in the two control modes were plotted, compared, and analyzed. Finally, the influence law of initial current, flow, and controller parameters on the dynamic and static characteristic index were analyzed in detail. The results show that compared with that in CFC mode, the displacement in DCL mode is smaller, and the adjustment time is shorter. The hydrostatic force is equal to the electromagnetic force in DCL mode when the rotor returns to the balance position. Moreover, the system in DCL mode has better robustness, and the initial flow has a more obvious influence on the dynamic and static characteristic indexes. This study provides a theoretical basis for stable suspension control and the safe and reliable operation of the MLDSB.

Study of a Modified Obstruction Free Pressure Sensor Based Flow Transducer Using Hall Sensors

In the present paper, a modified obstruction free pressure sensor-based flow transducer has been developed using Hall sensors. This technique is a modified version of the earlier inductive method. In this transducer, the fluid pressure in the pipeline is taken as the flow sensing parameter, and various drawbacks of the earlier inductive technique are eliminated. A prototype unit of the transducer is developed and studied in the present work. The transducer consists of two identical C-type Bourdon gauges, each fitted with an identical permanent magnet and Hall sensor assembly to sense the fluid pressure under flow condition and static pressure under no flow condition. The difference between the two Hall sensor outputs is found to vary nonlinearly with flow rate. The mathematical relations describing the working of the prototype unit are derived in the paper. The static characteristic curves of the proposed flow transducer are determined experimentally and reported in the paper. The characteristic curves are found to follow the derived equations to a very good extent with negligible percentage deviation from best-fit nonlinear characteristic.

ABOUT ONE METHOD OF IMPROVING THE STATIC CHARACTERISTIC MAGNETOELASTIC SENSORS

The article is devoted to improving the static characteristics of magnetoelastic sensors. Using the energyinformational method, techniques for improving the static characteristic are identified. By implementing these techniques, the design of a magnetoelastic sensor is proposed. The design scheme of the proposed magnetoelastic sensor, the electrical connection diagram of the sections of the measuring windings and the principle of operation of the sensor are given. An expression of the static characteristic for estimating its degree of nonlinearity is obtained.

DEVELOPMENT OF METHODS AND MANAGEMENT TOOLS AEROGASDYNAMICS PROCESSES AT MINING SITES

The practical development of the algorithm for optimal control of mine ventilation was preceded by comprehensive studies of the specific features of mining sites in order to obtain their mathematical description. The latter includes the static and dynamic characteristics of objects, i.e. the relationship between input and output values. The purpose of the research: to develop methods and management tools aerogasdynamics processes on mining sites of coalmines. Research methods. The methodology based on the system approach; modern methods of mathematical statistics, decision theory; mathematical logic devices; factor analysis; mathematical modeling; set theory and system analysis. To determine the dynamic characteristics of aerogasodynamic processes, experimental methods were used, divided into active and passive. The active method consists in con-structing a dynamic model of airing objects by approximating the transition curve obtained because of special effects on the airing object with an analytical expression. Statistical dynamics methods were used to obtain dynamic characteristics based on normal operation data. The method of correlation analysis was used. Results of research: experimental verification showed that the maximum relative error of in determining the methane concentration from the static characteristic constructed using a modified technique does not exceed 10 %. The value of the error was determined by comparing the static characteristic obtained by the modified correlation analysis method with the exact static characteristic of the airing object. The latter were found with regard to dynamic properties of the object and additive structures aerogas dynamics processes. Conclusion. The method of correlation analysis can be used to determine the dependence of the methane flow rate on the airflow rate in the steady-state mode, i.e. the static characteristic q = f (Q) for the site and lava. To determine the static characteristics based on the data of normal operation with a limited observation interval (5-10 days), a modified method of correlation analysis is proposed. Small values of the relative error of indicate the possibility and feasibility of using a modified correlation analysis technique to construct a static characteristic of the airing object based on random processes of methane concentration and air flow obtained during normal operation of the site. The static characteristics C= f (Q) and q= f(Q) are widely used to determine the mathematical expectations of the methane concentration and flow rate of mining sites, in the modeling of ventilation facilities and in the analysis and synthesis of mine ventilation control systems.