Simple Control Technique Research Articles

Sensorless Control of Low-Cost Single-Phase Hybrid Switched Reluctance Motor Drive

This paper presents a sensorless-controlled, low-cost, low-power, and variable-speed drive system suitable for fan and pump applications. The main advantages of this drive system are the low system cost, simple converter structure, and simple but robust sensorless control technique. The drive motor is a special hybrid switched reluctance motor. The proposed sensorless control method beneficially utilizes the stator side PM field and its performance is motor parameter independent. The unique low-cost drive system solution, simple and robust sensorless control features of this drive system, is demonstrated in detail in this paper. Important design details for practical implementation of the sensorless control algorithm are included. The complete drive system performance is validated using a prototype drive system.

A Scheme for the Power Control in a DFIG Connected to a DC Bus via a Diode Rectifier

This paper deals with a new conversion topology for doubly-fed induction generators (DFIGs) suitable for wind energy conversion systems integrated in microgrids. It consists of a DFIG which is fed by a pulse width modulation converter on the rotor and with the stator connected to a dc grid through a diode rectifier. In this configuration, the stator diode rectifier and the rotor-side inverter share the same dc bus, so that the conventional grid-side inverter is avoided. Since only a diode rectifier designed for the full power and a reduced power inverter are required, this layout allows a cheap and effective integration of the DFIG with other generating and storage systems connected to the same dc bus. A simple control technique suitable to regulate the power delivered to the dc grid is proposed. The scheme is based on the regulation of the amplitude of a suited fraction of the rotor flux linkage: the optimal value of this fraction is theoretically deduced in order to minimize the DFIG derating due to the current harmonics. The effectiveness of the proposed control is proven by simulations and experimental tests.

A new stability result for nonlinear cascade time-delay system and its application in chaos control

Based on the converse Lyapunov stability theorem and invariant set theory, this paper presents a new theorem for the nonlinear cascade delay system. With this new proposed method, a lot of coupled items can be taken as zero items. So the whole system can be converted to a very simple form. Also, a simple chaos control technique is proposed for the uncertain time-delay Lorenz chaotic system via this new method. The controller designed is linear and easy to be implemented. Simulation results for uncertain chaotic systems are provided to illustrate the effectiveness of the proposed scheme.

Simple digital current control strategy for single‐phase grid‐connected converters

This study proposes a simple digital current control technique for single-phase grid-connected voltage source converters. Unlike conventional strategies, the proposed method does not require any proportional-integral or proportional-resonant controller, fictitious phase generation, reference frame transformation and decoupling network; thus, it has the advantages of simplicity and reduced computational efforts. The suggested digital technique only uses a simple proportional controller in its structure and can be directly implemented on available digital signal processors. A digital controller parameter design procedure is proposed which ensures stability and near-zero steady-state error under all circumstances. Simulation and experimental results confirm that the proposed technique provides a fast and accurate current tracking with minimum harmonic distortions.

Experimental control of Triatoma infestans in poor rural villages of Bolivia through community participation.

BackgroundTriatoma infestans is the main vector of Chagas disease in the southern cone countries. Present control strategies based on indoor and outdoor residual insecticide spraying are not sufficient to control disease transmission, particularly in Bolivia. Techniques based on the management of the human environment may be good alternatives or supplements.MethodsSocial and entomological surveys were carried out in four villages of Bolivia situated in the dry inter-Andean Valleys and the Chaco region. Risk factors for house infestation by T. infestans were identified, and an eco-health intervention based on education and community participation was carried out to reduce the risks of house infestation. It consisted of implementing simple and low cost vector control techniques such as coating of mud walls, cleaning activities and removal of poultry that enter rooms to lay eggs.ResultsThe eco-health intervention significantly reduced the number of infested bedrooms, the mean abundance of T. infestans in bedrooms and beds, especially in the Chaco region. Mud wall coating was well accepted and could be proposed as a supplementary tool to the National Program of Chagas Disease Control to enhance the effects of insecticide sprayings.ConclusionsEven if cleaning activities were still neglected, community participation proved to be effective in reducing house infestation.

탄템 GMA 용접공정의 표면비드높이 예측을 위한 STACO모델 개발에 관한 연구

One of the main challenges of the automatic arc welding process which has been widely used in various constructions such as steel structures, bridges, autos, motorcycles, construction machinery, ships, offshore structures, pressure vessels, and pipelines is to create specific welding knowledge and techniques with high quality and productivity of the production-based industry. Commercially available automated arc welding systems use simple control techniques that focus on linear system models with a small subset of the larger set of welding parameters, thereby limiting the number of applications that can be automated. However, the correlations of welding parameters and bead geometry as welding quality have mostly been linked by a trial and error method to adjust the welding parameters. In addition, the systematic correlation between these parameters have not been identified yet. To solve such problems, a new or modified models to determine the welding parameters for tandem GMA (Gas Metal Arc) welding process is required. In this study, A new predictive model called STACO model, has been proposed. Based on the experimental results, STACO model was developed with the help of a standard statistical package program, MINITAB software and MATLAB software. Cross-comparative analysis has been applied to verify the reliability of the developed model.

A taper angle control technique using thin-film layer stiction phenomenon

We propose a simple taper angle control technique which can be easily achieved by using conventional thin-film deposition and wet etching processes. Based on the proposed technique, the taper angle can be controlled below 30° by varying the thickness of the shade layer which will support the top layer by means of the thin-film stiction phenomenon. By applying the proposed technique to the thin-film line resistor structure, we can confirm that variations of the resistance and the heat generation of the thin-film line formed cross the shade structured multiple thin-film line bumps can be suppressed below 6%, while those of the line resistor formed over multiple line bumps without the shade layer are increased by 54.5% and 246.6%, respectively.

A Hybrid Resonant Converter Utilizing a Bidirectional GaN AC Switch for High-Efficiency PV Applications

This paper introduces a novel isolated hybrid resonant converter with smooth transition between multiple operating modes. With the simple addition of a bidirectional ac switch, the highly efficient series resonant converter operating in the discontinuous conduction mode is combined with a phase-shifted full-bridge buck converter and a pulsewidth-modulated boost converter in order to provide high power conversion efficiency over a wide input-voltage operating range utilizing a simple topology and simple control techniques. First, the topology is introduced, and the converter's operating modes are discussed. Next, closed-loop input-voltage controllers are designed for the different operating modes, and a smooth transition technique is introduced using a two-carrier modulation scheme. Experimental results are provided to verify the proposed system using a 300-W prototype that achieved a 97.5% California Energy Commission weighted efficiency with a 30-V input including all auxiliary and control losses.

Operation and design issues of a doubly fed induction generator stator connected to a dc net by a diode rectifier

The operation of a doubly fed induction generator (DFIG) connected to a dc net is considered in this study. The dc net is connected to the stator of the DFIG by a diode rectifier and simultaneously feeds the rotor-side inverter, which is used to control the machine. When the dc net operates at constant voltage, this solution preserves the possibility to work with a low flux at low speed, and, at the same time, reduces the cost of the power electronics. In fact, the only needed electronic converter is the rotor inverter designed for a fraction of the machine power. After introducing a simple control technique, the study proposes an analytic model for the steady-state operation and discusses the design specifications of the DFIG for given values of the dc voltage and of the power of the wind turbine. The most appropriate stator and rotor rated powers, rated stator voltage and turns ratio of the DFIG are deduced. Simulations and experimental results are presented in order to support the theory.

Tracking control of a leg rehabilitation machine driven by pneumatic artificial muscles using composite fuzzy theory.

It is difficult to achieve excellent tracking performance for a two-joint leg rehabilitation machine driven by pneumatic artificial muscles (PAMs) because the system has a coupling effect, highly nonlinear and time-varying behavior associated with gas compression, and the nonlinear elasticity of bladder containers. This paper therefore proposes a T-S fuzzy theory with supervisory control in order to overcome the above problems. The T-S fuzzy theory decomposes the model of a nonlinear system into a set of linear subsystems. In this manner, the controller in the T-S fuzzy model is able to use simple linear control techniques to provide a systematic framework for the design of a state feedback controller. Then the LMI Toolbox of MATLAB can be employed to solve linear matrix inequalities (LMIs) in order to determine controller gains based on the Lyapunov direct method. Moreover, the supervisory control can overcome the coupling effect for a leg rehabilitation machine. Experimental results show that the proposed controller can achieve excellent tracking performance, and guarantee robustness to system parameter uncertainties.

Decentralized simple adaptive control of nonlinear systems

SUMMARYRecently, the passivity results for linear time‐invariant systems were successfully extended to nonlinear and nonstationary systems, thus guaranteeing stability of adaptive control of nonlinear square systems. Based on this theoretical development, this paper presents the development of a new class of direct adaptive controllers, which employ a new decentralized adaptation law mechanism that is developed from the simple adaptive control technique. The resulting direct adaptive control methodology is referred to as decentralized simple adaptive control. A simplification of this new control algorithm, referred to as decentralized modified simple adaptive control, is also presented. In addition, it is shown that both control methodologies can be modified to avoid divergence in practical situations, where the trajectory tracking errors cannot reach zero. Using Lyapunov direct method and Lasalle's invariance principle for nonautonomous systems, the formal proof of stability is established. As well, a numerical simulation study for a trajectory tracking problem by a rigid‐joint manipulator is presented to illustrate the new adaptive control approaches. Copyright © 2013 John Wiley & Sons, Ltd.

Almost Passivity and Simple Adaptive Control in Discrete‐Time Systems

AbstractSuccessful implementations of simple direct adaptive control techniques in various domains of application have been presented over the last two decades in the technical literature. The theoretical background concerning basic conditions needed for stability of the controller and the open questions relating the convergence of the adaptive gains have been clarified recently, yet only for the continuous‐time algorithms. Apparently, asymptotic tracking in discrete time systems has been possible only with step input commands and the scope of the so called “almost strictly positive real (ASPR)” condition has also remained not clear. This paper expands the feasibility of discrete simple adaptive control methodology to include any desired input commands and almost all real‐world systems. The proofs of stability are also rigorously revised to solve the ultimate adaptive gain values question that has remained open until now. Finally, a complex algebraic loop that seemed to be inherent in discrete ASPR systems and might prevent the use of passivity properties in discrete systems has also been eliminated.

Adaptive Control for the Stabilization and Synchronization of Nonlinear Gyroscopes

Recently, we introduced a simple adaptive control technique for the synchronizationand stabilization of chaotic systems based on the Lasalle invariance principle. The method is very robust to the effect of noise and can use single-variable feedback toachieve the control goals. In this paper, we extend our studies on this technique tothe nonlinear gyroscopes with multi-system parameters. We show that our proposedadaptive control can stabilize the chaotic orbit of the gyroscope to its stable equilibrium and also realized the synchronization between two identical gyros even whenthe parameters are assumed to be uncertain. The designed controller is very simple relative to the system being controlled, employs only a single-variable feedbackwhen the parameters are known; and the convergence speed is very fast in all cases.We give numerical simulation results to verify the effectiveness of the technique andits robustness in the presence of noise.

Simple control technique for interleaved inverters with magnetically coupled legs

Recent works of different authors have shown that the use of intercell transformers in interleaved inverters bring many improvements to this kind of parallelism. However, even though a balanced current distribution is necessary and not guaranteed by the converter itself; just a few of those studies are focused on the modelling and control of the inverter. Moreover, the fact that the paralleled modules are coupled and that the control signals are not updated simultaneously have not been considered yet. In this way, the current paper takes those facts into account and proposes a simple procedure for modelling and control a single-phase interleaved inverter. A mathematical analysis, some simulation and experimental results are shown in order to prove the simplicity and effectiveness of the proposed procedure.

T-S Fuzzy Tracking Control of a 2-DOF Rehabilitation Robot Using System Identification

Achieving excellent tracking performance for a 2-DOF rehabilitation robot actuated by pneumatic artificial muscles (PAMs) is very difficult, due to the high nonlinearity and time-varying behavior associated with gas compression and the nonlinear elasticity of bladder containers. This paper proposes a Takagi-Sugeno (T-S) fuzzy model control to improve control performance and establish a 2nd order system model using a recursive least square method. The proposed approach decomposes the model of a nonlinear system into a set of linear subsystems. In this manner, the design of the controller in the T-S fuzzy model is capable of using simple linear control techniques to provide a systematic framework with which to design a state feedback controller. The analysis of stability is performed by using the Lyapunov direct method. We employed the powerful LMI Toolbox of MATLAB to solve linear matrix inequalities (LMIs) to determine controller gains. Experimental results verify that the proposed controller can achieve excellent tracking performance.

Measurements and Correlations of Diffusivities of Nitrous Oxide and Carbon Dioxide in Monoethanolamine + Water by Laminar Liquid Jet

The molecular diffusivities of nitrous oxide (N2O) with aqueous monoethanolamine (MEA) solutions up to 12 M were studied over a temperature range from 298.15 to 333.15 K under atmospheric pressure using a laminar liquid jet absorber. The diffusivities of CO2 in aqueous MEA solutions were calculated by the “N2O analogy” method. A simple and effective thermal control technique was used to control the temperatures of gas and liquid in the laminar liquid jet absorber. The rates of absorption were determined by measuring the flow of gas needed to replace the gas absorbed. The results showed that the diffusivities of both N2O and CO2 into aqueous MEA solution decrease with the increase of the concentration of MEA, and increase with an increase of the temperature of the solution. The relationship between the diffusivity and the viscosity of the solution roughly agrees with the modified Stokes–Einstein equation, but an exponent mathematical model was employed to simulate the diffusivity data and shows a better ag...

Analysis and control of wind-driven self-excited induction generators connected to the grid through power converters

The analysis of the wind-driven self-excited induction generators (SEIGs) connected to the grid through power converters has been developed in this paper. For this analysis, a method of representing the grid power as equivalent load resistance in the steady-state equivalent circuit of SEIG has been formulated. The technique of genetic algorithm (GA) has been adopted for making the analysis of the proposed system simple and straightforward. The control of SEIG is attempted by connecting an uncontrolled diode bridge rectifier (DBR) and a line commutated inverter (LCI) between the generator terminals and three-phase utility grid. A simple control technique for maximum power point tracking (MPPT) in wind energy conversion systems (WECS), in which the firing angle of the LCI alone needs to be controlled by sensing the rotor speed of the generator has been proposed. The effectiveness of the proposed method of MPPT and method of analysis of this wind-driven SEIG-converter system connected to the grid through power converters has been demonstrated by experiments and simulation. These experimental and simulated results confirm the usefulness and successful working of the proposed system and its analysis.

Direct active and reactive power control of single-phase grid-tie converters

In this study, a simple digital power control technique for single-phase grid-tie converters is proposed. The suggested technique is based on the application of dead-beat control theory to the instantaneous powers in the virtual two-axis reference frame. A voltage estimation scheme is added to the proposed direct power control algorithm that allows grid voltage sensorless operation. The simulation and experimental results confirm that the proposed control strategy provides fast, accurate and decoupled power control with a lower alternating current distortion.

T–S fuzzy model-based tracking control of a one-dimensional manipulator actuated by pneumatic artificial muscles

Pneumatic artificial muscle (PAM) has highly nonlinear and time-varying behavior due to gas compression and nonlinear elasticity of the bladder containers. Hence, it is difficult to achieve excellent tracking performance when using classical control methods. This study proposes a Takagi–Sugeno (T–S) fuzzy model-based control for improving control performance. The proposed approach decomposes the model of a nonlinear system into a set of linear subsystems. This allows, the T–S fuzzy model-based controller to use simple linear control techniques providing a systematic framework for the design of a state feedback controller. Stability analysis is carried out using Lyapunov direct method. The powerful LMI Toolbox in MATLAB is employed to solve linear matrix inequalities (LMIs) to obtain the controller gains. Experimental results verified that the proposed controller can achieve excellent tracking performance under different disturbances.

Applying Differential-Mode Transformer to Current Sharing With Current Ripple Considered

A simple current-sharing control technique for the switching power supply is presented herein, which is based on the concept of the differential-mode transformer and which makes the load current evenly shared well among phases all over the line voltage and load current ranges. This current-sharing structure is very simple, and it makes the efficiency relatively high at light load, which is quite suitable for industrial applications with standby power considered. In this circuit, a synchronously rectified switch is used to further upgrade the efficiency, and the coupling output inductors in copolarity are utilized to decrease the phase current ripples. In this paper, the detailed basic operating principles, together with mathematical deductions, are first described, and second, some simulated and experimental results are provided to demonstrate the proposed control strategy.