Direct Vector Control Research Articles

Robust Control Method of Induction Machine against Temperature Variation

This paper proposes a control method robust against the rotor temperature variation for the induction machine used in the xEV traction application. The rotor resistance (or time constant) of the induction machine varies with the rotor temperature so that its torque control performance will be degraded if this variation is not properly compensated. In this paper, firstly a direct vector control method, which is based on the rotor flux estimator using the current model in the synchronous reference frame, is adopted in order to control the DQ-axis rotor fluxes independently. Secondly, the rotor time constant variation is compensated utilizing the flux estimation difference between the voltage and current models. This method has no transition region which is inevitable in the conventional method that uses the current model in the low speed region and the voltage model in the high speed range for estimating the rotor flux. The robustness to the temperature change of the proposed method is validated through the experiment in the motoring and regeneration modes.

A novel direct-current vector control technique for single-phase inverter with L, LC and LCL filters

Single-phase grid-connected converters (GCCs) are widely used to connect small-scale distributed renewable resources to the grid. However, unlike a three-phase system, design of the vector control for a single-phase GCC is more challenging. This paper presents a novel vector control design for a single-phase GCC based on a direct current vector control method. The design of the proposed vector controllers considered different filtering schemes, including L, LC and LCL filters. The behavior of the proposed direct current vector control is investigated through both simulation and hardware experimentation. Both demonstrate that the proposed control approach has strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy various control needs of single-phase GCCs under different filtering configurations.

New adaptive vector control methods for induction motors with simpler structure and better performance

This paper deals with the vector control, including both the direct vector control (DVC) and the indirect vector control (IdVC), of induction motors. It is well known that the estimation of rotor flux plays a fundamental role in the DVC and the estimation of rotor resistance is vital in the slip compensation of the IdVC. In these estimations, the precision is significantly affected by the motor resistances. Therefore, online estimation of motor resistances is indispensable in practice.

Comparative Study of PI, RST, Sliding Mode and Fuzzy Supervisory Controllers for DFIG based Wind Energy Conversion System

This work aims to present a comparative study of four controllers for Double Fed Induction Generator (DFIG) based Wind Energy Conversion System (WECS). The DFIG is directly connected to the grid and driven by the rotor through an AC/DC/AC converter. A model was developed for each component (Turbine, DFIG and Rectifier-Filter-Inverter) of the wind system. The PWM control method is applied to the inverter to drive the DFIG from the rotor circuit. To ensure high performance and better enforcement of DFIG, a direct vector control strategy of active and reactive power of the stator has been developed. The synthesis of conventional PI controller and advanced RST, Sliding Mode (SM) and Fuzzy Supervisory (FS) controllers is performed. The system’s performance has been tested and compared according to reference tracking, robustness, and disturbance rejection. A set of simulation studies are carried-out on a WECS model to prove the effectiveness of the proposed controllers design.

Full Decoupling Control of Two-Connected Motor Drives with Matrix Converter Supply

Multi-phase converters are required mainly for feeding variable speed multi-phase drive systems. This paper discusses one such solution by using direct ac-ac converter (matrix converter) that can be used to supply a six-phase and three-phase two-connected motor drive system. Matrix converter based two-motor drive system is presented for the first time in this paper. Two stator windings of six-phase and three-phase machines when connected in series while the rotors may be connected to different loads. Appropriate phase transposition is introduced while connecting the series stator winding to obtain decoupled control of the two machines. This paper proposes a scalar modulation scheme with three intervals technique of three-phase to six-phase matrix converter supplying series-connected six-phase and three-phase induction machine drive system. The dynamic decoupling of each machine from the group is obtained using the direct vector control algorithm. Mathematical modeling of the series-connected two-machine showed the possibility of independent control of each machine in the group. The independent control is demonstrated by analyzing the characteristics of the stator current references and speed of each machine under direct vector control scheme. The viability of the proposed control techniques is proved using analytically and simulation approach

Automatic speed control of an asymmetrical six-phase induction motor using emotional controller (BELBIC)

An induction motor IM with two sets of three-phase windings in stator is called a six-phase IM SPIM. SPIM has lower torque pulsation compared to a three-phase IM and using SPIM, the power rating of inverter legs can be reduced. This paper offers a high performance intelligent controller for speed automatic control of a SPIM. A brain emotional learning based intelligent controller BELBIC is proposed as the speed controller. This emotional controller has simple structure with high auto learning feature and it is independent of parameters variations. A direct vector control in rotor flux frame based on space vector pulse width modulation SVPWM is used to decouple flux and torque control of the SPIM like a conventional three-phase machine. In this work, the d-axis current and speed reference signals are accurately tracked. An overview of the BELBIC is provided. A comparison with the conventional PI controller and Sliding Mode Control SLMC points out the superiority of the proposed BELBIC in speed response and torque ripple. Experimental results indicate that the BELBIC achieves a good speed regulation with a less control effort and torque ripple.

Bi input-extended Kalman filter-based speed-sensorless control of an induction machine~capable of working in the field-weakening region

This study introduces a novel bi input-extended Kalman filter (BI-EKF)-based speed-sensorless direct vector control (DVC) of an induction motor (IM). The proposed BI-EKF-based estimator includes online estimations of the stator stationary axis components of the stator currents, i_{s\alpha} and i_{s\beta}; stator stationary axis components of the rotor flux, \varphi_{r\alpha} and \varphi_{r\beta}; rotor angular velocity, \omega_m; stator resistance, R_s; rotor resistance, R_r; and load torque t_L, as well as the magnetizing inductance, L_m, by only supposing that the stator phase currents and voltages are measured. Thus, the speed-sensorless DVC of the IM with the inclusion of the proposed estimator is able to be perfectly operated at a wide speed range, varying from zero speed to beyond the rated/based speed under the extreme variations in R_s, R_r, t_L, and L_m . The simulations confirm the effectiveness of the proposed BI-EKF-based estimator and, consequently, the speed-sensorless DVC of the IM.

Direct Vector Control With Fuzzy Current Controller for Three-phase Induction Motor

This article proposes a Direct Vector Control (DVC) method with a Fuzzy Logic Current Controller (FLCC) for three-phase induction motor. The conventional DVC method has two PI current controllers. With the aim to reduce the quantity of these controllers, we propose a single FLCC to substitute both PI controllers. The FLCC calculates the quadrature components of the stator voltage vector which are necessary to maintain the load. The rule base for the proposed controller is defined as a function of the stator current error components, and FLCC utilizes trapezoidal and triangular membership functions for the fuzzification of its inputs. The switching frequency is constant with the space vector modulation technique used in the DVC method. The performance of the proposed FLCC controller is analyzed through several tests such as: trapezoidal and triangular speed profile, step change in speed and step change in load with constant speed. The simulation and experimental results show that the proposed FLCC ensures decoupling current control and low current ripple, validating the proposed controller.

A New Approach for Controlling Direct-Driven PMSG Wind Turbines

This paper presents control of wind energy conversion system (WECS) with permanent magnet synchronous generator (PMSG). With the modern power electronic technology, direct-driven PMSG have been increasingly used in wind turbine manufactures. In PMSG wind turbine with two back-to-back voltage source converter (VSC) are used like a commercial passive rectifier followed by an insulated gate bipolar transistor (IGBT) inverter. This paper investigates the new approach for controlling the direct-driven PMSG wind turbines; it has two side-by-side voltage source pulse width modulation (PWM) converters. The paper investigates new approach based on direct current vector control method and also investigates the conventional vector control. Thisnew approach has to control both the machine side converter (MSC) and grid side converter (GSC). The control strategy is developed for integrated control of PMSG for maximum power extraction, dc-link voltage control and grid voltage support control. The WECS have been developed using Matlab Simulink software to compare the conventional vector control method with proposed approach under steady state and gusty wind conditions.

Modified Indirect Vector Control Technique for Current-Source Induction Motor Drive

Medium-voltage (MV) drives are generally based on either voltage-source inverters or current-source inverters (CSIs). CSIs feature simple topology, motor-friendly waveforms, power reversal capability, and short-circuit-proof protection; hence, they are widely used as high-power MV drives. Direct vector control (DVC) CSI drives ensure improved performance by decoupled control of the machine flux and torque using two independent control loops. Despite the excellent performance of DVC, this scheme faces practical challenges, like dc offset in the stator model and machine parameter dependence. Conventional indirect vector control (IVC) CSI drives are known for reduced computational burden and less machine dependence. However, conventional-IVC CSI drives exhibit poor dynamic response and transient field misorientation due to the absence of a dedicated flux control loop. In this paper, a modified IVC technique is proposed featuring superior decoupling and field orientation using only two extra proportional-integral current controllers with additional motor current feedback signals. The proposed-technique effectiveness is examined experimentally, on a scaled low-voltage prototype, as well as using simulation results.

Performance Improvements with Advanced AC Drives in Plate Shearing Line at Steel Plant

This paper represents the comprehensive study, analysis and results achieved by various data evaluation of AC drive system over DC drive system in Essar steel limited in India. With innovations in advanced direct torque control and vector control technologies, performance of AC drives is similar to DC drives in entire speed range. Usage of these advance speed control techniques in AC drives gives excellent results to achieve desired torquespeed characteristics, dynamic response and over load capabilities similar to DC drives. In February 2010, replacement of DC drive system by AC drive system was carried out in hot rolled plate shearing line (PSL), which is cut to length application line in steel plant. Before replacement, design calculation of AC system was carried out for matching the plant requirements. By various technical and fi nancial comparisons, it is found that use of AC drives is more economical in comparison with DC drives.AC drives ensure improvements on energy effi ciency, reliability and enhancement of production with reduction in cost, maintenance and equipment down time. After replacement of DC drives to AC drives, following performancs ase observed in PSL: Energy saving of 1.88 kWh/t. Production rate increased from 55 t/h to 95 t/h. Line speed increased from 19.5 meters per minute (m/min) to 23 m/min. Line stoppage time reduced from 2000 minutes to 300 minutes per annum.

MRAS Based Sensorless and Sensor Vector Control and Smooth Transient Between Them

Dynamic control, like vector control is an essential feature of every modern AC drive. In some cases it might be very important to provide continuous operation in case of encoder failure. It further means that the transient between sensor vector control and sensorless vector control has to be smooth. To obtain that a modified vector and sensorless vector control algorithms were designed. To allow smooth transitions, both sensor and sensorless control share common flux model. In this paper a novel robust MRAS-based speed estimator based on error between current estimators output and measured current and modifications of direct sensor vector control are presented. Theoretical analysis of estimators and design of adaptation loop is described. Finally, simulation and experimental results are shown.

속도제어를 위한 유도전동기 자속추정 시뮬레이터 적용에 관한 연구

본 논문에서는 전 속도 영역에서 안정적인 자속추정이 가능한 유도전동기 자속추정방법을 제안 하였다. 제안된 방법은 전압, 전류, 속도 등의 정보를 통하여 자속각을 연산하는 유도전동기 직접벡터제어방식을 이용하였다. 유도전동기 벡터제어에 있어서 자속정보는 필수적이기 때문에 정확한 자속을 추정하기 위한 방법으로 저속영역에서 는 전류모델 자속 추정기를, 고속영역에서는 전압모델 자속 추정기를 각각 이용함으로써 전 속도영역에서 정확한 자속을 추정할 수 있었다. 또한 기본적인 속도, 전류, 자속제어기는 PI제어기를 이용하였으며, 각각의 적분에 의한 오차를 보상하기 위하여 Anti-windup PI 제어기를 추가하였다. 제시한 제어기의 타당성을 알아보고자 Matlab / simulink를 이용하여 전류모델, 전압모델 자속 추정기를 설계하여 정확한 자속추정이 이루어짐을 확인하였으며, 유도 전동기 벡터제어 시 간접벡터와 직접벡터방식의 파라미터 영향에 따른 분석을 통해 보다 정밀한 제어가 이루어짐을 확인하였다. 이와 같은 시뮬레이션 결과를 분석 하여 제시한 알고리즘의 타당성을 입증하였다. In this paper, flux estimation method at the Induction motor is applied to stability flux estimate of possibility in overall speed domain. angle operation has voltage and current and speed information using the Induction motor direct control method. Induction motor direct control is material to flux information. Exact flux estimation method to using current model flux estimator of low-speed domain and voltage model flux estimator of high-speed domain. Speed and current and flux controller using PI controller. And error of integral requital for add to Anti-Windup PI controller. Verified to performance of Current model Flux controller and voltage model flux controller using Matlab / Simulink. Analysis has parameter influence of direct vector control and indirect vector control at the Induction motor vector control. So, verified to minute control. Analyzed to simulation result and proof to validity of presented algorithm.

Control of HVDC Light System Using Conventional and Direct Current Vector Control Approaches

With the advance of power electronic technology, the application of HVdc light systems based on voltage-source insulated gate bipolar transistor (IGBT) converters has increased rapidly in renewable, microgrid, and electric power systems. This paper proposes an optimal control strategy for an HVdc light system using a direct current vector control mechanism. The proposed approach is compared with the traditional vector control method for different HVdc control requirements, such as active power, reactive power, and grid voltage support control. A limitation of the conventional control mechanism is analyzed through a theoretical study and computer simulation. Closed-loop control evaluation demonstrates that the proposed approach works well for HVdc light system control both within and beyond the physical constraints of the system, such as rated power and saturation of pulse width modulation (PWM). The evaluation also shows that the conventional control technique could result in over voltage and system oscillation, especially when the controller operates beyond the PWM saturation limit.

High-performance sensorless vector control of induction motor drives using artificial intelligent technique

This paper presents a sensorless speed observer method of an induction motor using an artificial intelligent technique in direct field-oriented control system. The proposed sensorless vector control system consist of an adaptive observer of rotor flux in order to accurately estimate stator resistance and speed simultaneously, without affecting drive performances. The observer is associated with a direct vector control drive to rotor flux orientation for induction motor and uses the stator voltages and currents as inputs. To improve performance in a wide operating range, and achieve low sensitivity to parameter variations and external influences, the system uses an intelligent adaptive mechanism based on fuzzy logic approach to estimate the speed and a simple PI controller to determinate the stator resistance. The algorithm developed is robust and effective; it also provides accurate estimates, a good trajectory tracking with the different dynamics presented. Numerical experiments are presented to illustrate the feasibility of the proposed technique. Copyright © 2010 John Wiley & Sons, Ltd.

Bi Input-extended Kalman filter based estimation technique for speed-sensorless control of induction motors

This study offers a novel extended Kalman filter (EKF) based estimation technique for the solution of the on-line estimation problem related to uncertainties in the stator and rotor resistances inherent to the speed-sensorless high efficiency control of induction motors (IMs) in the wide speed range as well as extending the limited number of states and parameter estimations possible with a conventional single EKF algorithm. For this aim, the introduced estimation technique in this work utilizes a single EKF algorithm with the consecutive execution of two inputs derived from the two individual extended IM models based on the stator resistance and rotor resistance estimation, differently from the other approaches in past studies, which require two separate EKF algorithms operating in a switching or braided manner; thus, it has superiority over the previous EKF schemes in this regard. The proposed EKF based estimation technique performing the on-line estimations of the stator currents, the rotor flux, the rotor angular velocity, and the load torque involving the viscous friction term together with the rotor and stator resistance is also used in the combination with the speed-sensorless direct vector control of IM and tested with simulations under the challenging 12 scenarios generated instantaneously via step and/or linear variations of the velocity reference, the load torque, the stator resistance, and the rotor resistance in the range of high and zero speed, assuming that the measured stator phase currents and voltages are available. Even under those variations, the performance of the speed-sensorless direct vector control system established on the novel EKF based estimation technique is observed to be quite good.

Simulation of Induction Machine Drive by Composite Model Flux Observer

 Abstract—This paper presents a robust simulation of direct vector control of induction machine (IM) drive on the rotor flux direction with composite model flux observer. In the indirect vector control of IM, current reference values are used for estimation angle of the rotor flux space vector (ARFSV), however using current reference values instead of current real values can decrease accuracy of ARFSV. In the direct vector control, current real values (current feedback) estimate the ARFSV. ARFSV estimation can be performed by current model flux observer and voltage model flux observer. These observers have their own limitations. The composite model reduces disadvantages of every individual ones. Simulation of composite model is applied to induction machines and obtained results compare to the classical current and voltage models. The composite model approach shows great advantages over those classic ones, a.e. speed control over wide range of motor operation and enough short settling time. All these remarkable advantages support application of composite model in ARFSV.

Learning improvement by using Matlab simulator in advanced electrical machinery laboratory

This paper deals with using simulators such as MATLAB/SIMULINK to work on complicated problems in electrical machines. Simulation of direct vector control of induction machine (IM) drive on the rotor flux direction with composite model flux observer can improve electrical machine learning's of graduate and under graduated students, hi the indirect vector control of IM, current reference values are used for the estimation angle of the rotor flux space vector (ARFSV), however using current reference values instead of current real values can decrease accuracy of ARFSV. hi the direct vector control, current real values (current feedback) estimate ARFSV. The ARFSV estimation can be performed by the current model flux observer and voltage model flux observer. These observers have some restrictions. But The composite model reduces disadvantages of every individual ones. In fact, Simulation of the composite model is applied to induction machines to get results compare to the classical current and voltage models. The interesting point is that the composite model approach shows great advantages over those classic ones, i.e. speed control over the wide range of motor operation with enough short settling time. All these remarkable benefits support the application of composite model in ARFSV. © 2010 Published by Elsevier Ltd.

Fuzzy Logic Speed Controller for Direct Vector Control of Induction Motor

Fuzzy Logic Speed Controller for Direct Vector Control of Induction Motor

Switching EKF technique for rotor and stator resistance estimation in speed sensorless control of IMs

High performance speed sensorless control of induction motors (IMs) calls for estimation and control schemes that offer solutions to parameter uncertainties as well as to difficulties involved with accurate flux/velocity estimation at very low and zero speed. In this study, a new EKF based estimation algorithm is proposed for the solution of both problems and is applied in combination with speed sensorless direct vector control (DVC). The technique is based on the consecutive execution of two EKF algorithms, by switching from one algorithm to another at every n sampling periods. The number of sampling periods, n, is determined based on the desired system performance. The switching EKF approach, thus applied, provides an accurate estimation of an increased number of parameters than would be possible with a single EKF algorithm. The simultaneous and accurate estimation of rotor, R r ′ and stator, R s resistances, both in the transient and steady state, is an important challenge in speed sensorless IM control and reported studies achieving satisfactory results are few, if any. With the proposed technique in this study, the sensorless estimation of R r ′ and R s is achieved in transient and steady state and in both high and low speed operation while also estimating the unknown load torque, velocity, flux and current components. The performance demonstrated by the simulation results at zero speed, as well as at low and high speed operation is very promising when compared with individual EKF algorithms performing either R r ′ or R s estimation or with the few other approaches taken in past studies, which require either signal injection and/or a change of algorithms based on the speed range. The results also motivate utilization of the technique for multiple parameter estimation in a variety of control methods.