Vector Control System Research Articles

Grid voltage local regulation by a doubly fed induction generator–based wind turbine

Voltage regulation at point of common coupling using a doubly fed induction generator–based wind energy conversion system is achieved through reactive power control. Wind energy conversion system produces reactive power when the voltage is less than grid nominal voltage and it consumes it in the opposite case. In this article, a method to achieve this goal is proposed. It consists of controlling the reference value of the vector control system in order to affect the wind energy conversion system reactive power output. Two situations have been simulated. Sudden voltage increase and decrease were applied to the control system. Satisfying results have been obtained since the voltage at point of common coupling has been restored back to its initial value.

Thrust vector control of upper stage with a gimbaled thruster during orbit transfer

In launching Multi-Satellite with One-Vehicle, the main thruster provided by the upper stage is mounted on a two-axis gimbal. During orbit transfer, the thrust vector of this gimbaled thruster (GT) should theoretically pass through the mass center of the upper stage and align with the command direction to provide orbit transfer impetus. However, it is hard to be implemented from the viewpoint of the engineering mission. The deviations of the thrust vector from the command direction would result in large velocity errors. Moreover, the deviations of the thrust vector from the upper stage mass center would produce large disturbance torques. This paper discusses the thrust vector control (TVC) of the upper stage during its orbit transfer. Firstly, the accurate nonlinear coupled kinematic and dynamic equations of the upper stage body, the two-axis gimbal and the GT are derived by taking the upper stage as a multi-body system. Then, a thrust vector control system consisting of the special attitude control of the upper stage and the gimbal rotation of the gimbaled thruster is proposed. The special attitude control defined by the desired attitude that draws the thrust vector to align with the command direction when the gimbal control makes the thrust vector passes through the upper stage mass center. Finally, the validity of the proposed method is verified through numerical simulations.

Improved Output Voltage Quality using Space Vector Modulation for Multilevel Inverters

Space vector modulation (SVM) has received wide acceptance due to many benefits over other techniques such as higher output voltages, lower total harmonic distortion (THD), high-efficiency and flexible to be implemented in vector control systems. In digital implementation, the SVM equations can be optimally computed by eliminate the use of complex forms. In this paper, the simple SVM based on twolevel inverter is employed for higher levels of inverters. This is to retain the simplicity of SVM computation for three-level and five-level cascaded H-bridge multilevel inverter (CHMI). Moreover, the proposed method utilizes two controller boards to perform high computational workloads and to eliminate glitch and error problems. Experiment results show that the THD of output voltage in five-level CHMI gives the smallest value among the results obtained from other levels.

Electromechanical resources of a frequency-controlled synchronous electric drive in continuous periodic operating modes

The possibility of increasing overload capability and reducing power loss in a frequency-controlled synchronous electric drive operating in a continuous periodic mode is considered. A definition of a “continuous periodic mode” is given. A functional diagram of vector control system of synchronous electric drive is presented. The statement of a problem in the study of electric drives is formulated. A modeling method of a synchronous electric drive making it possible to recognize the maximum loads upon heating of a synchronous motor is described. Results of computer modeling of the continuous periodic operational mode of a salient pole motor with continuous and optimal regulation of armature magnetic flux are presented. The resource of synchronous motor is determined on the basis of the criterion of motor torque allowable upon heating. A comparative analysis of power loss of synchronous motor in the continuous periodic mode with continuous and optimal regulation of armature magnetic flux is carried out. The conclusion is drawn that the use of optimal regulation of armature magnetic flux in vector control systems of synchronous electric drives operating in continuous periodic mode is efficient.

CFD modeling for flow field characterization and performance analysis of HGITVC

The present study aims at numerically investigating the performance of the Hot Gas Injection Thrust Vector Control (HGITVC) system within the divergent part of a supersonic nozzle. For this purpose, the following measures were taken: considering the flow to be compressible and turbulent, using k-ω-SST model for turbulence modeling, simulating and comparing single and dual injections using a three dimensional and multi block in-house code and validating simulation results using experimental data. The findings indicate that the strength of secondary jet rises as the injection area and injector to nozzle pressure ratio increases. Moreover, it is proved that increase in strength of injection leads to decrease in the amplification factor and increase in the deflection angle and the axial thrust. In addition, a sharp drop in the performance of HGITVC is observed not within acquired permissible range for strength of injection which reduces the system performance. These findings lead us to conclude that in comparison with single injection, the dual injection cannot increase the thrust ratio which is the main objective of this study. However, it helps to inject more gas without shock impingement phenomenon and also improves the Axial Thrust Augmentation (ATA).

Analysis of the dynamic performance of a variable-frequency induction motor drive using various control structures and algorithms

A comparative analysis of the dynamic characteristics of field-oriented induction motor drive control systems relying on the main magnetic flux linkage vector reference, space-vector pulse width modulation (SVPWM) of the voltage inverter output, and direct torque control (DTC) is carried out using the Matlab/Simulink program package, with the parameters of the induction motor model used being the same. A changeover from stepless vector control systems to systems using microprocessors and modern controllable frequency converters operating on the principle of relay control entails possible changes in the properties of the electric drives being controlled. In this connection, there is a need to compare the dynamic performance characteristics of an electric drive with a slave vector control system (with an idealized frequency converter), referred to as electric drive 1 (ED1), an electric drive with a DTC system (ED2), and an electric drive using direct torque control and SVPWM (ED3). Modeling has shown that the response time of the torque control loop in all the control systems considered is the same, the time delay being no more than 0.01 s. On the whole, speed control transients in all of the above systems take their course in one and the same way. The differences in flux linkage control transients between ED2 and ED3, on the one hand, and ED1, on the other hand, are due to the differences between the methods used to form the electromagnetic torque. No provision is made in the above control systems for the stabilization of the magnitude of the flux linkage vector. At low loads, the flux linkage automatically follows the load. In an ED3 with direct torque control, the calculation of the necessary instant magnitudes of the voltage vector projections and the SVPWM based formation of the voltages applied to the motor allows implementation of a fast-response control system with minimal harmonic distortions and torque pulsations. The control system coefficients are calculated beforehand. The speed controller is adjusted to the technical optimum. In the main flux linkage oriented control system, it is also desirable to use an SVPWM-based formation of the motor voltage.

Structured Singular-Value Analysis of the Vega Launcher in Atmospheric Flight

Using the structured singular value , an independent control law assessment is presented for the Vega launcher thrust vector control system. A systematic uncertainty modeling and analysis process is illustrated to retrieve and structure driving perturbation combinations affecting competing control system design requirements. It is demonstrated how analysis not only complements and generalizes classical frequency-domain stability assessments but also how it applies naturally as a performance indicator to manage the requirements tradeoff space. The proposed methodology is shown to be reliable and computationally more efficient than widespread verification and validation techniques that rely on random sampling via Monte–Carlo analysis. Although not meant as a replacement of these traditional approaches, analysis effectively complements and enhances the verification and validation tasks by guiding the analyst toward worst-case convergence over the uncertain parameter search space. The attitude dynamics in atmospheric flight of Europe’s lightweight Vega launcher is assumed throughout the paper. Comparative robustness analysis results are shown between pre- and postflight assessments.

Development of vector control system of DFIG using graphically programmed DSP

Development of vector control system of DFIG using graphically programmed DSP

Usage of invariant immersion filters in sensorless system of vector control of PMSM

Usage of invariant immersion filters in sensorless system of vector control of PMSM

Closed-loop actuator identification for Brazilian Thrust Vector Control development

This paper presents the current status of the development of a Thrust Vector Control system for new Brazilian launch vehicles, looking for the highest performance by closed-loop servo hydraulic actuator identification. Therefore, a test environment with a mass-spring test bench is introduced. Engineering models of two different types of actuators, three-way and four-way valve controlled pistons with direct drive control valves are developed. The dynamic responses are experimentally determined and subsequently mathematically modeled.

Experimental and simulation testing of thermal loading in the jet tabs of a thrust vector control system

The paper discusses the temperature changes in mechanical jet tabs in a system of rocket motor thrust vector control, estimated by the simulation and experimental tests methodology. The heat transfer calculation is based on complex computational fluid dynamics simulations of both the nozzle and external tab flows, as the comprehensive integral flow zones with high flow parameters gradients. Due to a complexity of the model for flow calculations, the experimental estimation of the calculated results is carried out. The temperature is measured by jet tabs embedded thermocouples, and conducted through the rocket motor static tests. A good agreement of the calculated and measured results is achieved. The main aim of the developed method is to establish an approved calculation tool for designing new TVC systems in order to avoid disadvantages due to overheating.

Investigation and Comparison Effects of Fluid Injection Type in Thrust Vector Control

In this research, the effects of some liquid side injection from nozzle wall into exhaust gas of combustion chamber are studied. The side injection against main flow is as elliptical solid thing that change the symmetric of flow field on nozzle wall and causes some different pressure distribution on wall, and finally causes thrust vector deviation. Flows interaction causes some physical phenomena as bow shock wave in front of injection region. This paper explain the effects of this wave and variation velocity & pressure distribution at different cross sections of flow field and comparison results of air and other liquid fluid in thrust vector control system. The results are compared with experimental data and have well agreement with them. The results show that Freon is one of best injection liquid for this type of thrust vector control. Performance of Injection is optimum in relative position 35 to 40% nozzle divergence length.

Vector Control Specialized for Switched Reluctance Motor Drives

SUMMARYThis paper proposes vector control specialized for a switched reluctance motor (SRM) drive. Because it is a unipolar drive, a sinusoidal current with a dc offset is applied to each circuit instead of the conventional trapezoidal current. The current consists of dc and ac components which can be identified by their generation of a (virtual) rotor flux and rotating stator magnetic field, respectively. Thus, the vector control system can be developed in the same way as conventional ac machines. The proposed technique provides new mathematical models of SRMs on a rotating reference frame and achieves precise and fast torque response and advanced operations such as linear torque‐current control and maximum‐torque‐per‐ampere control. The vector control theory was verified through simulations and experiments.

Wind turbine emulator based on blade element momentum theory for variable‐speed wind power generation system

This paper proposes a wind turbine emulator (WTE) based on the blade momentum theory, and tests the variable‐speed wind power generation system using a pulse‐width modulation (PWM) converter to verify the accuracy of the emulator. The behavior of the wind turbine for natural wind is reproduced by the WTE based on the proposed theory. The variable‐speed wind power generation system employs a vector control system to control the torque and speed of the permanent magnet synchronous generator in the converter side. The windmill rotational speed is controlled to maximize the efficiency of the wind turbine against wind velocity. And the active power and reactive power are controlled in the inverter side, and the generated power is sent to the grid while controlling the DC link voltage to be constant at the same time. The behaviors of the WTE are compared with the simulation results and experimental results using a real wind turbine. These experimental and simulation results show that the test bench with the proposed WTE has sufficient performance and accuracy to verify variable‐speed wind generator systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Study and Realization of SVPWM Algorithm’s Key Technology

Control algorithm is the core of AC servo system. In order to improve the performance of system, on the basis of vector control system and space vector pulse width modulation (SVPWM), inverse matrix and projection of out U on plane rectangular coordinate system were used to determine the nonzero vector movement time 2 1 t t、 . Then, a calcula- tion method of vector switch point T cm1 ,T cm2 ,T cm3 was given. Finally, a judgment method of sector which vector locate was given based on the one-to-one relationship between index number and sector. Simulation was carried on and some simulation results show that the system has good dynamic response and steady-state accuracy.

A Novel Sensorless Fuzzy Sliding-Mode Control of Induction Motor

A novel fuzzy sliding-mode structure has been proposed for the model reference adaptive system(MRAS) based sensorless control of an induction motor in this paper. The design includes a hybrid MRAS from measured stator terminal voltages and currents. The estimated speed is used as feedback in an indirect vector control system achieving the speed control without using shaft mounted transducers. Fuzzy sliding-mode structure includes two nonlinear controllers, one of which is sliding mode type and the other is PI-fuzzy logic based controller, the latter define a new control structure. Both controllers are combined by means of an expert system based on Takagi-Sugeno fuzzy reasoning. The sliding mode controller acts in the steady state. The new structure has two advantages: sliding-mode controller increasing system stability and PI-like fuzzy logic based controller reducing the chattering in permanent state. The scheme has been implemented and experimentally validated.

Radial displacement-sensorless control for bearingless induction motor

Aimed at rotor position identification of bearingless induction motor( BIM),a displacementsensorless control scheme based on modified back electromotive force was proposed for the BIM. Firstly,to eliminate the flux observation error,on the basis of the back electromotive force( BEMF) method,the low pass filter was added to the flux observation model of radial suspension force winding. At the same time,the amplitude and phase deviation caused by the addition of low pass filter were compensated. Secondly,the modified flux observation model of radial suspension force winding was obtained and the rotor radial deviation was obtained according to the relationship equation between flux and displacement. Thus,the radial displacement self-detecting was achieved. Finally,a displacement-sensorless vector control system of the BIM was established using the presented position detection method. The simulation results show that the control system not only can accurately detect the rotor radial position,but also has good speed and torque characteristics. The further experimental results also show that the method had a good ability of radial displacement self-detecting.The BIM can realize stable suspension operation with displacement-sensorless.

Review on model reference adaptive system for sensorless vector control of induction motor drives

The most frequently used electrical machine in various modern high-performance drive applications is the induction motor (IM), especially its squirrel cage type rotor counterpart. The high-precision, efficient control of sensorless IM drives throughout its operating range demands an exact knowledge of a few of the IM parameters. The stator resistance, rotor resistances are such important IM parameters whose variations may lead to improper estimation of speed over the whole operating range in sensorless drives. Numerous methods for the estimation of speed of high-performance sensorless IM drives taking into account the effect of parameter variations have been developed. This paper aims at providing a review of the major model reference adaptive system (MRAS) based techniques applied for the estimation of speed of such sensorless drives. This paper is illustrated throughout with relevant mathematical equations, experimental and simulation results, associated to different MRAS-based sensorless vector control of the IM drive.

Numerical Characterisation of Jet-Vane based Thrust Vector Control Systems

<p>Computational fluid dynamics methodology was used in characterising jet vane based thrust vector control systems of tactical missiles. Three-dimensional Reynolds Averaged Navier-Stokes equations were solved along with two-equation turbulence model for different operating conditions. Nonlinear regression analysis was applied to the detailed CFD database to evolve a mathematical model for the thrust vector control system. The developed model was validated with series of ground based 6-Component static tests. The proven methodology is applied toa new configuration.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 261-264, DOI: http://dx.doi.org/10.14429/dsj.65.7960</strong></p>

Indirect vector control with simplified rotor resistance adaptation for induction machines

A novel indirect vector control system for induction machines is proposed. To ensure accurate rotor flux orientation in face of severe thermal drift of the rotor resistance during practical operation, the system features a new rotor resistance adaptation method. The latter is based on the elimination of the q-axis rotor flux, which is calculated from steady-state relations of the induction machine. Compared with other rotor resistance adaptation methods found in the literature, for example, observer-based and model reference adaptive system-based methods, the proposed one poses much less computation burden and is quite convenient for online implementation. The basic principle and theoretical analysis are presented. The effects of other motor parameters on the adaptation method are also investigated. Based on the investigation results, a stator resistance compensation algorithm is incorporated to reduce the impact of incorrect stator resistance at low speeds. Some non-negligible issues in practical applications, such as dead-time effect and transport delay of digital pulse-width modulation process, are also investigated and taken care of. Simulation and experimental results show good dynamic and steady-state performance.