Flux-oriented Control Research Articles

Virtual Power Grid Flux-Oriented Vector Control for Three-Phase Voltage-Type PWM Rectifier

More considerable power distortions are produced by the non-reversible diode-bridge rectifiers in the power system’s AC-DC conversion technology. In addition, bridge-rectifiers worsen energy quality and decrease power factor. Three-Phase Pulse Width Modulation (3phase-PWM) rectifiers have seen rapid growth in use due to recent breakthroughs in power device technology. Its benefits include a unity power factor, no harmonic distortion, and pulsating direct currents. An actual power regulation technique based on a novel virtual power grid controller is suggested to cheaply regulate a 3phase-PWM converter with good performance. The study introduces a new sensorless control scheme to improve the 3phase-PWM-performance rectifier. The proposed control technique employs the virtual power grid flux-oriented vector control with a Second-Order Generic Integral with Instantaneous Phase Lock Loop (SOGI-IPLL) to overcome the problems inherent in relying only on low-pass filter estimates. The virtual power grid flux value may then determine the phase difference. The IPLL takes the phase angle as an input and is utilized to construct the power-oriented vector control. The proposed power grid flux-oriented control strategy combines the VFidea with SOGI-IPLL to circumvent the restrictions imposed by relying only on an integrator of low-pass filters (LPF) to provide an estimate. A refined Virtual flux (VF) estimator with direct power control can improve management at a cheaper cost and more efficiently. The modeling findings demonstrate that the DC voltage input and power grid throughput of the 3phase-PWM rectifier can be successfully regulated in both the rectification and inversion states, allowing for the effective functioning of the 3phase-PWM rectifier.

Hybrid Flatness-Based Control of Dual Star Induction Machine Drive System for More Electrical Aircraft

Abstract This paper develops a precise method control system for tracking control of a power drive system based on a multi-phase machine under motor parameter and load torque variations. By adding a simple feedforward term based on the flatness theory, a conventional flux oriented control (FOC) can be enforced to have a perfect tracking performance under model parameter and load torque variations. Hence, a hybrid flatness-based control (HFBC) technique is applied to the control of a dual star induction machine (DSIM) and compared to a classical vector control strategy regarding tracking behaviour, robustness, and perturbations rejection. Finally, the simulation and experimental results are provided to verify the effectiveness of the proposed HFBC under uncertainties such as motor parameter and load torque variations. Furthermore, an enhancement of the drive system’s control performances is demonstrated by the improvement of the technique of separation of the objectives of tracking and disturbance rejection. The simulation and experimental results are presented, demonstrating the superiority of the HFBC.

On the Induction Motor Rotor Flux Estimation in the Electric Traction Systems with Rotor Flux-Oriented Control

Characterized by very good performance in both steady-state and dynamic regimes and also by a relatively simple control structure, the induction motor control with rotor flux orientation is frequently adopted in electric drive systems, especially in electric traction applications. This paper analyses the possibilities of rotor flux estimation in a real Romanian electric traction system of locomotives. Thus, to estimate the magnitude of rotor flux and the angu-lar position of the rotor flux vector, two possibilities are identified and discussed. First, the use of the sensed speed and stator currents is taken into consideration, and then the use of the measured supply voltages and the stator currents is the second alternative. Dedicated algorithms were designed for their related control. Both variants are analyzed through the results of the simulations obtained based on the specific models created in the Matlab/Simulink software. Four values of the imposed speed are taken into account in the performed analysis. It is highlighted that, in real conditions where the drive system is provided with speed sensor and there is no sine filter for the distorted motor supply voltage, the best option to estimate the rotor flux is to use the measured speed and the stator currents.

Enhanced Low-Speed Characteristics With Constant Switching Torque-Controller-Based DTC Technique of Five-Phase Induction Motor Drive With FOPI Control

The Classical hysteresis controller-based DTC (C-DTC) of an induction motor is a simple control scheme with better dynamics and steady-state characteristics when compared with the flux-oriented control (FOC) scheme. The major drawbacks of the C-DTC scheme are variable switching frequency and high average torque ripple under different rotor speeds. In this paper, the two-level five-leg inverter-controlled five-phase induction motor drive with constant switching torque controller-based DTC (PI-CST-DTC) scheme is introduced to improve the steady-state performance with constant switching frequency under various operating speeds. However, the proposed PI-CST-DTC exhibits slower torque and slower speed dynamics w.r.t C-DTC which is due to the periodic occurrence of zero vectors under transients. These slower dynamics are improved with the help of the proposed fractional order PI (FOPI) constant switching torque controller-based DTC (FOPI-CST-DTC) method. With the help of the hardware results, it has been verified that the proposed FOPI-based CST-DTC exhibits improved low-speed steady-state and dynamic performance of the five-phase induction motor drive. The proposed CST-DTC techniques with PI and FOPI controllers are compared with C-DTC for torque ripple reduction and %THD analysis and dynamics through hardware results.

Harmonic Injection Strategy Considering Multiplane Iron Loss Impact With Optimal Magnetizing Flux Distribution for Multiphase Induction Machines

Lagging orientation error detuning induced by iron losses for multi-planes of multiphase IM under non-sinusoidal supply control triggers error in determination of calculated harmonic, fundamental air-gap flux advance angles and harmonic slip frequency. This in-turn leads to inaccurate harmonic injected currents, which are dependent on harmonic multiple of frequency for the corresponding plane with respect to fundamental plane frequency. This paper proposes the novel harmonic injection strategy considering the detuned impact of iron losses by keeping in view the complete iron loss modeling for both harmonic magnetizing flux orientation control (MFOC) and fundamental rotor flux orientation control (RFOC) planes. Furthermore, satisfaction of complete optimal flux distribution constraints for multiphase IM are taken into account which results in preserving optimal flux patterns throughout the mechanical loading particularly at low and medium load conditions. Contrary to other traditional orientation schemes, this paper adopts the MFOC and RFOC for harmonic and fundamental plane respectively for acquiring the aligned and synchronized control of harmonic and fundamental air-gap flux distribution. Detailed experimental results incorporating seven phase induction machine as prototype are utilized to evaluate the harmonic injected currents, advance angles, slip frequencies and induced EMF waveforms which validate the effectiveness of proposed scheme.

Analysis of the Stator Current Prediction Capabilities in Induction Motor Drive Using the LSTM Network

Abstract In modern areas of knowledge related to electric drive automation, there is often a need to predict the state variables of the drive system state variables, such as phase current and voltage, electromagnetic torque, stator and rotor flux, and others. This need arises mainly from the use of predictive control algorithms but also from the need to monitor the state of the drive to diagnose possible faults that have not yet occurred but may occur in the future. This paper presents a method for predicting stator phase current signals using a network composed of long-short-term memory units, allowing the simultaneous prediction of two signals. The developed network was trained on a set of current signals generated by software. Its operation was verified by simulation tests in a direct rotor flux-oriented control (DRFOC) structure for an induction motor drive in the Matlab/Simulink environment. An important property of this method is the possibility of obtaining a filtering action on the output of the network, whose intensity can be controlled by varying the sampling frequency of the training signals.

Dual Closed-Loop Control Strategy on Harmonic Plane for Multiphase Induction Motor With Harmonic Injection Based on Air-Gap Flux Orientation Control

Multiphase motors, compared to three-phase motor, have many advantages, such as multiple degrees of freedom and flexible control. However, if these advantages are used incorrectly, it will increase the loss of the motor and decrease the efficiency. In response to this problem, this article lists the three limiting conditions that make the air-gap flux as quasi-trapezoidal waveform and analyzes the reasons why the traditional method cannot make the air-gap flux perfectly distributed. Therefore, a dual closed-loop feedback control structure on the harmonic plane was proposed. In this article, the feasibility and stability of the proposed method are analyzed. A series of comparative experiments on a seven-phase induction motor with concentrated windings platform is given. Finally, a conclusion that the proposed method not only can achieve a better electromotive force (EMF) waveform but also can increase torque per ampere is drawn.

Field-oriented control based on adaptive neuro-fuzzy inference system for PMSM dedicated to electric vehicle

Permanent magnet synchronous motor (PMSM) speed control is generally done using flux-oriented control, which uses conventional proportional-integral (PI) current regulators, but still remain the problem of calculating the coefficients of these regulators, particularly in the case of control hybridization, the development of artificial intelligence has simplified many calculations while giving more accurate, and improved results, this paper presents and compares the performance of the flux oriented control (FOC) of a PMSM powered by pulse width modulation (PWM) using PI regulator, fuzzy logic control (FLC) and adaptive neuro-fuzzy inference system (ANFIS), in this work we present another approach of a neuro ANFIS using the hybrid combination of fuzzy logic and neural networks. This ANFIS is a very powerful tool and can be applied to various engineering problems. To make up for the deficiency of fuzzy logic controller. To understand the performance, characteristics, and influence of each controller on the system response, we use MATLAB/Simulink to model a PMSM (0.5 kW) powered by a three-phase inverter and controlled by the FOC, FOC-FLC, and FOC-ANFIS.

Harmonic and Fundamental Rotor Resistance Estimation Scheme for Multiphase Induction Motor Based on Nonsinusoidal Supply Control

In the absence of flux measurements, techniques of field orientations depend on motor parameters, particularly on rotor resistances. During operation in flux-oriented mode, online continuous estimation of harmonic and fundamental rotor resistances is important for multiphase IM. To limit the core saturation and to achieve the synchronous and aligned air-gap flux density distribution, the harmonic plane is based on magnetizing flux-oriented control (MFOC) whereas the fundamental plane is taken as rotor flux-oriented control (RFOC). Mismatch harmonic and fundamental resistances trigger deviations in the rotor and magnetizing flux and also cause misalignment in the resultant induced electromotive force (EMF) waveform which could, in turn, be the reason for over-excitation and under-excitation. This article formulates the simultaneous online identification of rotor resistances for particularly MFOC harmonic plane while the fundamental plane is RFOC based on the dot product of rotor flux and stator current for making a model reference adaptive system (MRAS). Mismatched stator resistance and dead time of inverter have a negligible effect on the reference model during steady state. Convergence and steady-state performance can be acquired for a variation of load conditions particularly at heavy loading. The validation of the proposed approach is verified through simulation and experiment results by incorporating a multiphase platform consisting of a seven-phase induction machine.

An Enhanced Linear ADRC Strategy for a Bearingless Induction Motor

To provide faster speed response, better current characteristics, more stable suspension, and stronger disturbance immunity for a bearingless induction motor (BIM) system, an enhanced linear active disturbance rejection control (ELADRC) strategy is proposed. First, based on the air-gap flux-oriented control, the speed LADRC and the suspension LADRC are, respectively, designed for the torque winding and suspension winding. The uncertainties and disturbance of the system are treated as a total disturbance in LADRC and linear extended state observer (LESO) is used to observe and compensate for it in real time. Second, by analyzing the defects of LADRC, the speed ELADRC and the suspension ELADRC with cascaded LESO are designed based on LADRC to improve the stability and disturbance immunity. Third, the stability and the tracking performance of the second-order ELADRC are analyzed. Finally, simulation and experimental comparisons of the PID control strategy, the LADRC strategy, and the ELADRC strategy are carried out. The analysis and results show that the proposed strategy not merely has good speed response and current characteristics and lowers the influence of load disturbance, but also realizes the fast and stable suspension of the rotor and improves the anti-disturbance performance of the suspension system.

Self-Correcting Virtual Current Sensor Based on the Modified Luenberger Observer for Fault-Tolerant Induction Motor Drive

Fault-tolerant control (FTC) solutions are increasingly being used in modern drive systems with AC motors. Such systems provide a higher degree of security and solutions that allow the on-line detection and localization of failures, as well as the switching of the control mode to a mode that allows us to continue the operation or safely stop the drive system. As the current sensors (CSs) are necessary to ensure precise control of the AC motors, in the event of their failure, one of two strategies can be used—hardware or software redundancy. The first strategy requires the use of additional measuring sensors. For this reason, the algorithmic solution, based on the Luenberger Observer (LO), has been proposed in this article as one of the software redundancy methods. In contrast to methods presented in the literature, the proposed solution allows one not only to compensate the stator current in a phase with a faulty CS, but also to adjust the correction of current estimation based on a measured signal in the other phase with a healthy CS. Extensive simulation studies in the direct rotor flux-oriented control (DRFOC) structure with the induction motor (IM) confirm the effectiveness of the proposed method. In addition, the proposed solution allows the drive system to be controlled even if all CSs are damaged.

Solve Coupled Axes Problem Without FOANR Based on Substitution Method to Control DFIG Used in Wind Application

In order to control output powers generated by doubly fed induction generator (DFIG) used in wind application (WA) many previous studies, mainly based on flux orientation control (FOC) and neglecting resistance to get a simple model of DFIG with decoupled axis. However, this control strategy requires several hypotheses: low and stability of grid voltage in order to orientated the statoric flux, high power of generator to neglecting statoric resistance. As a result that may not be present in realty due to direct connection between stator and the grid In addition to the presence of resistance, whatever the power of the generator, therefore the DFIG represents a complex model and required a nonlinear control without previous approaches closer to reality to respond highly against DFIG nonlinear model, this is the first paper presents a novel strategy to control nonlinear model of DFIG based on substitution method to solving (d,q) coupled axes without flux orientation and neglecting resistance (FOANR) and also does not take into account stability of grid voltage, for produce required reference active and reactive power by controlling the voltage of rotor side converter (RSC), using classical proportional-integral (PI) controller in a non-linear synthesis form by three methods :direct control (D) and indirect open loop (IOL) and indirect with power loop (IWPL),we compared three controls and check their performance towards the real model of DFIG to verify our control and proving its effectiveness without previous approaches. Finally, the simulation results of the studied controls are presented, analyzed and compared.in terms of power reference tracking, robustness to the parametric variation and the ability to respond to sudden wind speed variation.

Identify magnetising inductance and rotor resistance to improve the performance of the induction motor through IRFOC

To get a high dynamic performance of AC machines, field-oriented control was used. The best method of field-oriented control is an indirect rotor flux-oriented control. When applied this method of ...

Design and Control of Grid-Connected PWM Rectifiers by Optimizing Fractional Order PI Controller Using Water Cycle Algorithm

In this paper water cycle algorithm-based fractional order PI controller (FOPI) is proposed for virtual flux-oriented control of a three-phase grid-connected PWM rectifier. FOPI controller makes the PWM rectifier control more robust due to the fractional behavior. Fractional-order controllers have an additional degree of freedom, so a wider range of parameters is available to provide better control and robustness in the plant. The optimization and design of the FOPI controller are done using the water cycle algorithm (WCA). WCA is an optimization method inspired by monitoring the water cycle operation and flow of water bodies like streams and rivers toward the sea. The performance of the FOPI controller is compared with the classical integer order PI controller. The parameters of PI and FOPI controllers are optimized and designed using the WCA technique, leading to WCA-PI and WCA-FOPI controllers. The system is tested using MATLAB/Simulink. The simulation results verify the better performance of WCA-FOPI in terms of settling time, rise time, peak overshoot, and Total Harmonic Distortion (THD) of grid current. A robustness measurement with line filter parametric variations and non-ideal supply voltage (unbalance and distorted supply voltage) is carried out. The WCA-FOPI demonstrates more robustness as compared to WCA-PI. Simulation findings validate the WCA-FOPI controller outcomes as compared to WCA-PI in terms of control effect and robustness.

Active and Reactive Powers Control of DFIG Based WECS Using PI Controller and Artificial Neural Network Based Controller

The purpose of this study is to improve the control performance of a Doubly Fed Induction Generator (DFIG) in a Wind Energy Conversion System (WECS) by using both of the conventional Proportional-Integral (PI) controllers and an Artificial Neural Network (ANN) based controllers. The rotor-side converter (RSC) voltages are controlled using a stator flux oriented control (FOC) to achieve an independent control of the active and reactive powers, exchanged between the stator of the DFIG and the power grid. Afterward, the PI controllers of the FOC are replaced with two ANN based controllers. A Maximum Power Point Tracking (MPPT) control strategy is necessary in order to extract the maximum power from the of wind energy system. A simulation model was carried out in MATLAB environment under different scenarios. The obtained results demonstrate the efficiency of the proposed ANN control strategy.

Phase Voltage-Oriented Control of a PMSG Wind Generator for Unity Power Factor Correction

This paper presents the power factor control of a permanent magnet synchronous wind generator (PMSG) wind turbine using a phase voltage-oriented control (PVOC) scheme, which is different from the conventional rotor flux-oriented control (RFOC) method and without using a rotor position sensor or sensorless estimator. The proposed control system is operated in two separately synchronously rotating d-q frames. One is for a phase-locked loop (PLL) and the other is for the PVOC current control loop. A PI controller functioned as a low-pass filter in the PLL loop is designed for extracting the phase voltage angle for the coordinate transformation between the stationary α-β frame and the synchronously rotating d-q frame in the PVOC control loop. The d-q modeling of the PMSG with the three-phase voltage vector aligned on the d-axis is then derived and based on which an another PI controller followed by decoupling control is designed, so that the three-phase currents are in phase with the three-phase output voltages of the wind generator for unity power factor correction. The simulation results in PSIM show the performance of the proposed control system which is also experimentally verified by using a TI TMS320F28335 digital control chip.

A Constrained Non-Linear Model Predictive Controller for the Rotor Flux-Oriented Control of an Induction Motor Drive

Predictive controllers have been extensively studied and applied to electrical drives, mainly because they provide fast dynamic responses and are suitable for multi-variable control and non-linear systems. Many approaches perform the prediction and optimization process on-line, which requires a high computational capacity for fast dynamics, such as, for example, the control of AC electric motors. Due to the complexity of embedding constraints in controller design, which demands a high computational capacity to solve the optimization problem, off-line approaches are one of the choices to overcome this problem. However, these strategies do not deal with the inherent constraints of the drive system, which significantly simplifies the design of the controller. This paper proposes a non-linear and multi-variable predictive controller to control the speed and rotor flux of an induction motor, where the constraints are treated after the controller design. Besides dealing with the constraints of the electric drive system, our proposal allows increasing the stability of the system when the model does not incorporate disturbances and when parameter incompatibilities occur. Several computer simulations and experimental tests were performed to evaluate the behavior of the proposed controller, showing good performance to track the controlled variables under normal operating conditions, under load disturbances, parametric incompatibility, and at a very low rotor speed.

Electromechanical Coupling Modelling of High Speed EMUs with Rotor Field Oriented Control

According to the theory of vehicle system dynamics and rotor flux-oriented control (RFOC), an electromechanical coupling simulation model of transmission system of high-speed EMUs is established considering the effect of mechanical and electrical characteristics. Firstly, an EMUs multi-body system (MBS) model including is developed by Simpack software based on the structure and parameters of a high-speed EMUs, and a RFOC simulation model of traction transmission system is also built by the Simulink platform. Then two types of models are linked by Simpack co-simulation interface model. Consequently, the electromechanical coupling model of EMUs is developed. The computer simulation method is adopted to simulate the coupling system with RFOC. Simulation results indicate that the proposed model can effectively reveal the change of electrical performance of the high-speed EMUs, the coupling system has a good anti interference performance and robustness.

Induction-Machine-Based Starter/Generator Systems: Techniques, Developments, and Advances

The starter/generator (SG) system is widely used in various applications, including more-electric/hybrid electric aircraft (MEA/HEA) and hybrid electric vehicles (HEVs). The electric machine operates as a motor to provide the required torque to start the engine. Once the engine starts, the same electric machine transforms to a generator to produce electrical power. With the advantages of a simple and robust structure, low cost and maintenance, and a good overload capability, the cage-type induction machine (IM) is a competitive candidate for SG systems. The research on system topologies mainly focuses on dc power systems, while ac and hybrid ac/dc power systems are investigated to satisfy the diversity requirement for the power supply. A number of control strategies are intensely studied for the effective integration of the double functions of starting and generating, mainly including flux -oriented control (FOC) and direct torque control (DTC). Although there have been several reports on IM -based SG systems, many important aspects still must be investigated and improved

Control-Winding Direct Power Control Strategy for Five-Phase Dual-Stator Winding Induction Generator DC Generating System

A control-winding direct power control (CWDPC) strategy for a dc generating system based on the five-phase dual-stator winding induction generator is proposed and investigated in this article. For this generator, the flux-oriented control is usually employed in the previous work mainly for the sake of good static performance. However, the present control strategy has the limitation of the further enhancement of the dynamic properties. This article explores a CWDPC strategy to upgrade the dynamic performance of this generating system. The fundamental active power of the five-phase control winding (CW) relates to its dc bus voltage while the dc bus voltage on the five-phase power-winding (PW) side is related to the control of five-phase CW fundamental reactive power. By replacing inner current loops to power control loops, the CW instantaneous fundamental active and reactive powers are calculated through the power observer and regulated directly through two power-control loops. In the transient process, the CW fundamental active power changes slightly while the reactive power can be quickly controlled for fast recovery of the dc bus voltage on the five-phase PW side. As the system has an additional control degree of freedom, the third harmonic is also considered in the proposed strategy, and the corresponding implementation is given as well. The simulation and experimental results demonstrate that using the proposed CWDPC strategy, the system has shorter transient time and lower voltage change in the dynamic response than the flux-oriented control strategy, which means the dynamic performance is further improved.