Earticle

In this paper, the control technique of the stepping motor using back electromotive force(B-EMF) without encoder is investigated. The stepping motor generally uses the rotary encoder to detect the rotor position. Since this method increases the cost and the motor configuration size, the new closed-loop control method applied for the B-EMF was implemented by using current detect circuit, AD-converter, and micro controller unit(MCU). The contorl loop of stepping motor became very simplified. The current change of stepping motor measured by the amplifier was measured and analyzed, when the missing step is occurred. Based on the data from current feedback, position errors were compensated and confirmed by using AD-converter.

In this paper investigated the without encoder drive for stepping motor using back electromotive force(B-EMF). In generally stepping motor should be rotary encoder to rotor position, the rotary encoder is adopted to detect the position. But in this way increase cost and volume. This paper propose B-EMF & closed-loop method was implemented using current detect circuit, AD-converter and MCU(micro controller unit). So that stepping motor environment is very simplify. The current of stepping motor was measured by using amplifier. The change of current was measured and analyzed, when the missing step occurred. Based on data from current feedback, position errors were compensated and it was confirmed by using AD-converter.

The aim of this paper is to increase the performance of hysteresis compensation for Shape Memory Alloy (SMA) actuators by using inverse Preisach model in closed-loop control system. This is used to reduce hysteresis effects and improve accuracy for the displacement of SMA actuators. Firstly, hysteresis is identified by numerical Preisach model implementation. The geometrical interpretation from first order transition curves is used for hysteresis modeling. Secondly, the inverse Preisach model is formulated and incorporated in closed-loop PID control system in order to obtain desired current-to-displacement relationship with hysteresis reducing. The experimental results for hysteresis compensation by using this method are also shown in this paper.

This Paper presents the position tracking control of a closed-loop cylinder system using electro-rheological(ER) valve actuators. After manufacturing three sets of cylindrical ER valves on the basis of Bingham model of ER fluid, a 3 dof(degree-of-freedom) closed-loop cylinder system having the heave, roll and pitch motions is constructed. The governing equations of motion are derived using Lagrange's equation and a control model is formulated by considering nonlinear characteristics of the system. Sliding mode controllers are then designed fer these ER valve actuators in order to achieve position tracking control. The effectiveness of trajectory tracking control performance of the proposed cylinder system is demonstrated through computer simulation and experimental implementation of the sliding mode controller.

The building of distributed power and smart grid accelerates the development of intelligent contactor. The design of intelligent contactor has gradually attracted more attention. This review introduces the latest research progress of intelligent contactor including four aspects such as intelligent design and optimization, no-arc control technology, less bounce control technology and subsidiary structure and function. This review focuses on power electronics technology, artificial intelligence content algorithm, and feedback control and so on .Some ideas are proposed to be further studied. Finally, the intelligent contactor’s development is looked into with the future of China's energy management pattern.

It is well known that the electro-hydraulic actuator (EHA) system is exposed to the disturbances, uncertainties, and parameter variations which are caused by the changes in operating conditions for instance, total moving mass, supply pressure, servo-valve gain, bulk modulus, leakage coefficient, and friction. These problems pose to a great challenge in modelling and controller development for an EHA system. Degradation of the desired performance can be imposed if an improper control strategy is utilized. This paper discusses the fundamental study on the significant effect that leads to degradation of EHA system performance due to variation in the system parameters. A nonlinear EHA system model is developed and implemented in the simulation studies in open-loop and closed-loop control configuration. The finding shows that the servo-valve gain resulted the most influential parameters to the EHA system performance as compared to the total moving mass and supply pressure parameters. In order to overcome these issues, the utilized controller should be robust enough to overcome the entire operating range that against such disturbances, uncertainties, and parameter variations. Therefore, a nonlinear and the intelligent control approach may be necessary to be designed in order to overcome these difficulties.

The multistage compression is usually adopted for large tonnage powder pressing equipment to improve product quality. The first compression is the key process during the powder processing as the target pressure is small and the load is great fluctuant. The pressure in the first compression is likely to be much overshot that makes laminated products if conventional control strategy is applied. The control parameters of routine mode have bad adaptation because they change with the target pressure. In order to improve the accuracy of the pressure and adaptability of control parameters in the first compression, one strategy oriented to engineering application that includes data testing, parameter setting and control optimizing has been proposed. Real-time monitoring system with multi-channels based on LabVIEW is built, and the full-state of equipment can be acquired based on the system. The working statuses of control elements during the pressing process due to inertial force are optimized with the experimental data, and the segmented variable gain control strategy based on parameterization is developed and applied. The experimental results with the strategy during the first compression indicate that the pressure precision is raised from 0.3MPa and above (conventional opened-loop control) to 0.05MPa and below, and the pressing time is controlled in 300ms and below. The control strategy ensures the high accuracy and efficiency of pressing process and it is convenient to be applied in engineering.

With the increasing number of vehicles, society and environmental problems become much more seriously. Aiming at the serious problems, CNG engine, which has better emission performance, has been paid much more attention. However, the CNG engine also has its own disadvantages, such as engine power deterioration, great influence of different mixture ratios of the gas and air on the optimum ignition time of the engine, and so on. Therefore, adaptive control for the air-fuel ratio and ignition timing should be properly adjusted with the consideration of the engine power, economy and emissions. There are two methods of controlling the ignition timing: mechanical and electronic control. In this paper, we develop an adoptive control method based on electronic control. According to the verification, the method can improve the efficiency of the CNG engine. It can be shown the validity of the adoptive method.

The variable integral gain voltage and current double closed-loop control technique based on a PWM inverter is studied in this paper. To improve the response speed and steady-state accuracy of the system, the voltage and current double closed-loop control model is established at first, and then the fixed integral of double closed-loop control strategy is analyzed based on this model. Because variable integral gain control method can improve the control precision based on the double closed loop, the voltage and current double closed-loop control strategy with variable integral gain is proposed. Finally, a series of simulation and experiment results are accomplished to verify the validity of this method. It is shown that the dynamic response time is 2ms and the maximum voltage change rate is only at 0.5%, and the steady-state accuracy can reach 99.55%.

This paper describes a control method of turn-on/off angles to improve the efficiency of the switched reluctance generator(SRG) with a power closed-loop control system, and the inner-loop of the system is current hysteresis control. The SRG control system is constituted by the PI power controller and the two-level current hysteresis controller. By measuring and analyzing the system losses of different reference powers, speeds and turn-on/off angles, selection strategy of optimal turn-on/off angles is discussed. The proposed method is simple, reliable, and easy to achieve.

Chen and Chen(FSS, 1993, 159-168) presented a reasonable analytical model of fuzzy closed-loop systems and proposed a method to analyze the stability of fuzzy control by the relational matrix of fuzzy system. Chen, Lu and Chen(IEEE Trans. Syst. Man Cybern., 1995, 881-888) formulated the sufficient and necessary conditions on stability of fuzzy closed-loop control systems. Gang and Chen(FSS, 1996, 27-34) deduced a linguistic relation model of a fuzzy closed loop control system from the linguistic models of the fuzzy controller and the controlled process and discussed the linguistic stability of fuzzy closed loop system by a linguistic relation matrix. In this paper, we study more on their models. Indeed, we prove the existence and uniqueness of equilibrium state $X_e$ in which fuzzy system is stable and give closed form of $X_e$. The same examples in Chen and Chen and Gang and Chen are treated to analyze the stability of fuzzy control systems.

The presented paper gives an overview of several projects addressing the experimental characterization and control of the buffet phenomenon on 3D turbulent wings in transonic flow conditions. This aerodynamic instability induces strong wall pressure fluctuations and therefore limits flight domain. Consequently, to enlarge the latter but also to provide more flexibility during the design phase, it is interesting to try to delay the buffet onset. This paper summarizes the main investigations leading to the achievement of open and closed-loop buffet control and its experimental demonstration. Several wind tunnel tests campaigns, performed on a 3D half wing/fuselage body, enabled to characterize the buffet aerodynamic instability and to study the efficiency of innovative fluidic control devices designed and manufactured by ONERA. The analysis of the open-loop databases demonstrated the effects on the usual buffet characteristics, especially on the shock location and the separation areas on the wing suction side. Using these results, a closed-loop control methodology based on a quasi-steady approach was defined and several architectures were tested for various parameters such as the input signal, the objective function, the tuning of the feedback gain. All closed-loop methods were implemented on a dSPACE device able to estimate in real time the fluidic actuators command calculated mainly from the unsteady pressure sensors data. The efficiency of delaying the buffet onset or limiting its effects was demonstrated using the quasi-steady closed-loop approach and tested in both research and industrial wind tunnel environments.

A new on-line fault detection and isolation(FDI) scheme has been proposed for engines using an adaptive neural network classifier; this paper investigates the robustness of this scheme by evaluating in a wide range of operational modes. The neural classifier is made adaptive to cope with the significant parameter uncertainty, disturbances, and environmental changes. The developed scheme is capable of diagnosing faults in the on-line mode and can be directly implemented in an on-board diagnosis system(hardware). The robustness of the FDI for the closed-loop system with crankshaft speed feedback is investigated by testing it for a wide range of operational modes, including robustness against fixed and sinusoidal throttle angle inputs, change in load, change in an engine parameter, and all changes occurring simultaneously. The evaluations are performed using a mean value engine model(MVEM), which is a widely used benchmark model for engine control system and FDI system design. The simulation results confirm the robustness of the proposed method for various uncertainties and disturbances.

Modeling of the three phase electric arc furnace and its voltage flicker mitigation are the purposes of this paper. For modeling of the electric arc furnace, at first, the arc is modeled by using current-voltage characteristic of a real arc. Then, the arc random characteristic has been taken into account by modulating the ac voltage via a band limited white noise. The electric arc furnace compensation with static VAr compensator, Thyristor Controlled Reactor combined with a Fixed Capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive approach with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in the compensator control. Also, in closed loop control, two different approaches are considered. The former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. Finally, in order to show the effectiveness of the proposed methodology, the simulation results are provided.

Output filter is an essential part of a grid-connected inverter used for improving the quality of a grid-injected current. The use of LCL filters in power converters in microgrid applications is more preferred compared with L or LC filters because of their better harmonic attenuation capability. However, LCL filter still occupies a main part of the weight and volume of the whole system. Thus, more progress can be further developed with this consideration. In this paper, based on a 2.5 kW three-phase voltage source inverter, a magnetic-integrated LCL filter is designed by sharing an EIE-type core to reduce weight and size significantly. With the magnetic coupling influence taken into consideration, more effective design principles of the filter are discussed according to theoretical analysis and mathematical modeling. Meanwhile, a double closed-loop control strategy is utilized to eliminate the resonance introduced by the LCL filter and stabilize the system. Simulation and practical experiments are conducted with a detailed comparison between the discrete and integrated LCL filters, which can verify the feasibility and validity of the proposed method.

Wireless smart sensors, which have become popular for monitoring applications, are an attractive option for implementing structural control systems, due to their onboard sensing, processing, and communication capabilities. However, wireless smart sensors pose inherent challenges for control, including delays from communication, acquisition hardware, and processing time. Previous research in wireless control, which focused on semi-active systems, has found that sampling rate along with time delays can significantly impact control performance. However, because semi-active systems are guaranteed stable, these issues are typically neglected in the control design. This work achieves active control with smart sensors in an experimental setting. Because active systems are not inherently stable, all the elements of the control loop must be addressed, including data acquisition hardware, processing performance, and control design at slow sampling rates. The sensing hardware is shown to have a significant impact on the control design and performance. Ultimately, the smart sensor active control system achieves comparable performance to the traditional tethered system.

This letter presents an analytical framework for a performance analysis of the imperfect direct-sequence code division multiple access (DS-CDMA) closed-loop power control (CLPC) loop with loop delay, channel estimation error, and power control command bit error as the parameters under a Rayleigh flat fading environment. The proposed model is verified through a comparison between analytical results and simulation ones.

The method that the operating condition of Control Rod Drive Mechanism (CRDM) can be monitored without mounting sensors within CRDM housing was developed, and by using this developed method the closed-loop controller for the CRDM was designed which can optimize the performance and maximize the reliability of CRDM operation. Neural network is utilized as pattern recognition engine in detecting CRDM actuation. In this paper, most problems in previous open loop system are resolved. The control algorithms for closed-loop system ore developed and implemented within the hardware of timing controller based on microprocessor. All functions in the timing controller ore verified by means of real time CRDM simulator. The results show that the timing controller performs its intended functions properly.

A primary-side regulation (PSR) constant current (CC) output and constant voltage (CV) output AC-DC converter is proposed and an adaptive high-precision closed-loop constant current control scheme is put forward in this paper. In the CC mode, the converter adopts the closed-loop control strategy to realize that the switching period adaptively converges to twice the demagnetization time, which realizes the CC output. In addition, exactly detecting the demagnetization time is a prerequisite for obtaining a high-precision output current. Therefore, a demagnetization time detection circuit is designed to provide accurate and reliable demagnetization information. The control IC was fabricated with the Nuvoton 0.5um BCD process, and a 5 V/2 A prototype circuit was implemented to verify its performance. Experimental results show that the CC deviation is within ± 1.4%, which is lower than the target value of ± 2.0%. Under different loads and AC inputs, the conversion efficiency in the CC mode varies between 76.3% and 80.7%.

The amplitude error of phase modulator used in closed-loop fiber optic gyroscope has occurred by the temperature dependency of the electro-optic coefficient, and also can be due to the square-wave dither signal which is generally applied for eliminating the deadzone. This error can cause bias drift and scale factor error. This paper analyzes the temperature dependency of the modulation amplitude and the relationship with the scale factor of the gyroscope, and deals with an amplitude control method. The error calculation logic considering the dither signal is implemented on the signal processing module. The result of experiments from a prototype gyroscope shows the effect of the modulation amplitude control and a considerable improvement on performances.