Flux Linkage Research Articles

Parameter Identification of a Permanent Magnet Synchronous Motor Based on the Model Reference Adaptive System with Improved Active Disturbance Rejection Control Adaptive Law

Aiming at the problem that online parameter identification, based on the Model Reference Adaptive System (MRAS), is easily affected by the high-frequency noise of the sensor, an improved MRAS, based on variable bandwidth linear Active Disturbance Rejection Control (ADRC) adaptive law, is proposed. The proposed ADRC adaptive law, including an extended state observer, exhibits good anti-disturbance ability while effectively tracking the error signal through adjusting the bandwidth of the controller according to the observation error. When the observation error is large, the bandwidth of the controller is increased to enhance the tracking accuracy; in the opposite situation, the bandwidth is reduced to improve the anti-disturbance performance. To illustrate feasibility, a stability analysis of the proposed ADRC adaptive law is carried out and some comparison and validation experiments are designed to identify the inductance and flux linkage of the permanent magnet synchronous motor (PMSM). The experimental results show that the proposed method has better anti-disturbance performance than the MRAS based on traditional Proportional Integral (PI) adaptive law or switched PI adaptive law.

PF-MRAC-Based Elimination of Sensors in Solar-Powered PMSM Drive-Based Water Pumping System

The water pumping system powered by solar photovoltaic (PV) array and driven by permanent magnet synchronous motor demands a current-sensor to operate PV array at its maximum power and an encoder to implement field-oriented control of motor. Reduction in reliability and increment in system cost are the two major drawbacks that demands their elimination. Even the application of system for locations with high ambient temperature is limited as these sensors are temperature sensitive. In this work, power-factor based model-reference adaptive-control (PF-MRAC) to remove encoder as well as current-sensor is presented. Even stator winding resistance and rotor flux linkage are estimated by PF-MRAC. Thus, presented MRAC is independent of parameter uncertainty contrary to conventional MRAC. Besides, developed PF-MRAC does not contain integral and derivative operators, and hence it is free from saturation and noise problems. The estimated speed is used for estimation of PV power, which is then used for extracting maximum power from PV array, thereby removing current sensor. Besides, an additional converter is not required for realization of presented maximum power point tracking method. The developed PF-MRAC is realized on dSPACE Microlab box platform, and test results are acquired for various operating scenarios on laboratory prototype.

A New Hybrid Concentrated-Winding Concept With Improved Power Factor for Permanent Magnet Vernier Machine

This paper investigates a high power-factor permanent magnet vernier machine (PMVM) equipped with low-coupling hybrid concentrated-winding (CW). The proposed hybrid-CW, carrying both star- and delta-winding sets, exhibits a good filtering property to both sub- and super-order harmonics. Through the meticulous design of the short coil pitch, the ratio of inductance to magnet flux linkage is decreased, leading to a great improvement in power factor. The proposed low-coupling winding design contributes to further power factor improvement by reducing the inductance while retaining the magnet flux linkage. It is revealed that the mutual coupling between different coils of single phase and that between different windings of three phases are suppressed significantly in the hybrid-CW, thus leading to high power factor and potentially high fault tolerance. Finite element results show that the proposed hybrid-CW PMVM exhibits a significantly improved power factor up to 0.96 from 0.83 and 0.75, as compared with two counterpart PMVMs with open-slot and split-tooth structures, respectively. Benefiting from the magnetic gearing effect, the proposed PMVM has a promising active torque density of 40 Nm/L. Taking end-winding volume into consideration, the proposed PMVM exhibits an actual torque density of 21.98 Nm/L, which is 22.52% and 52.43% higher than the investigated open-slot and split-tooth counterpart PMVMs. Finally, a prototype is fabricated and tested to validate the high-power-factor and high-torque-density features of the proposed hybrid-CW PMVM.

Open-Delta Flux-Modulating Consequent Pole Motors

This paper proposes a new type of variable-flux permanent magnet motor, named “open-delta flux-modulating consequent pole motor” (OFCM). The armature winding ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W_a</i> ) of the proposed OFCM is connected in an open delta, and it also serves as a field winding ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W_f</i> ) by simultaneously supplying it with three-phase armature current and DC field current. The flux linkage of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W_a</i> can be adjusted by changing the field current. The flux-regulation capability and torque characteristics of the OFCM were investigated through finite element analysis (FEA) and experiments on a prototype machine. Using FEA, efficiency maps of the OFCM were also compared to those of a flux-modulating consequent pole motor (FCM) with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W_f</i> . The results show that the OFCM without <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W_f</i> has significantly higher efficiency and maximum torque than the FCM.

Синхронный многофазный электропривод с управлением по многоканальному принципу

A promising way to improve the technical and economic characteristics of an AC electric drive is to design it based on an executive synchronous motor with an increased number of phases of the stator winding. However, the specific nature of the m-phase (m &gt; 3) synchronous motor is determined by the energy transfer by the whole spectrum of spatial harmonics of the field. Thus, the task is to design an electromechanical system that takes this feature into account. The author has used the method to study the adjustment characteristics of an m-phase synchronous motor based on spectral vectors of electromagnetic parameters reduced to spatial harmonics of the field. A multichannel principle of realization of an m-phase synchronous electric drive is proposed. It ensures the targeted formation of the electromagnetic state of a synchronous motor through all its energy channels as a control object. Various ways of its implementation are considered. The realization of the multiphase synchronous motor can be carried out based on of the forced mutual orientation of the flux linkage vectors and the stator current for higher spatial harmonics, which ensures the creation of additional constant components of the electromagnetic torque. This design of electric drives is advisable, in particular, for mobile installations with low-voltage (autonomous) power sources.

Accuracy improvement of maximum torque per ampere control for interior permanent magnet synchronous motor drives reflecting PM flux linkage variations

Accuracy improvement of maximum torque per ampere control for interior permanent magnet synchronous motor drives reflecting PM flux linkage variations

Comparative Study on Fault-Tolerant Triple Three-Phase PM Machine Drive With Five Modular Windings

In this paper, five different triple 3-phase windings are presented for fault tolerant PM machine drive to achieve advanced turn short circuit fault (TSCF) current reduction effect. First, the five different winding configurations are briefly introduced and the reasons of TSCF reduction effect is explained. Then, the healthy performance and fault tolerant capabilities of several fault modes are investigated by detailed finite element (FE) prediction and test verification. They exhibit almost the same healthy performance. It is demonstrated that the zero sequence (ZS) flux linkages in Y connected winding is the fundamental factor of the huge TSCF current since the Y winding does not contain ZS current path. Thus, the Y-Δ winding exhibits the best the TSCF current suppression capability which creates the ZS current path to nullify the ZS flux linkages, and the delta winding ranks as the second which contains larger ZS circuit. The investigation provides effective approaches and solutions to obtain enhanced fault tolerant capability on the worst TSCF for the safety critical applications.

High-accuracy torque estimation and safety control for induction motor used in electric vehicles

As a power output unit, Induction Motor (IM) is widely used in Electric Vehicles (EV) due to its unique advantages of higher power density and better torque ability. With more complicated motor controller system, there are some hardware and software failures which bring some risks including EV unexpected acceleration or deceleration, therefore it is necessary to build high-accuracy torque estimation and safety control strategy. Firstly, hazard and safety concept are analyzed to make sure function safety goals and levels for IM system. Secondly, a novel method of high-accuracy torque estimation is proposed based on a rotor dynamic and composite flux linkage observer. Then, fault diagnosis and handling mechanisms of motor torque are designed to avoid hazards when it is a significant difference between motor estimation torque and vehicle requested torque. Finally, power test and Hardware in Loop (HIL) bench are configured to verify torque estimation accuracy and fault protection mechanisms rationality by comparing test results and injecting related faults. Experiment result shows that motor torque accuracy is within ±5 Nm and fault protection mechanisms can bring motor to safety state promptly.

RESEARCH THE EFFECT OF THE FRACTIONAL NUMBER SLOTS OF POLE ON WIND TURBINE GENERATION USING THE ENHANCED SPOTTED HYENA OPTIMIZATION ALGORITHM

The design of machines with permanent magnets is actively developing day by day and is often used in wind energy. The main advantages of such variable speed drives are high efficiency, high power density and torque density. When designing a wind generator with two rotors and permanent magnets, it is necessary to solve such a problem as the correct choice of the number of poles and slots to increase efficiency and minimize the cost of the machine. In this work, an improved spotted hyena optimization algorithm is used to obtain the optimal combination of slots and poles. This optimization algorithm makes it possible to obtain the number of fractional slots per pole and evaluate the operating efficiency of a wind generator with a double rotor and ferrite magnets. At the first stage of machine design, various combinations of slots are installed. Next, the optimal combination is selected from various slot-pole combinations, taking into account the Enhanced Spotted Hyena Optimization (ESHO) algorithm, in which a multi-objective function is configured. Accordingly, the multi-objectives are the integration of reverse electromotive force, output torque, gear torque, flux linkage, torque ripple along with losses. Analysis of the results obtained shows that the proposed algorithm for determining the optimal slot combination is more efficient than other slot combinations. It has also been found that the choice of slot and pole combination is critical to the efficient operation of permanent magnet machines.

МОДЕЛИРОВАНИЕ СИСТЕМЫ «СИНХРОННЫЙ ГЕНЕРАТОР – ПРЕОБРАЗОВАТЕЛЬ ЧАСТОТЫ – СИНХРОННЫЙ ДВИГАТЕЛЬ»

The relevance of the use of AC-AC power transmission systems on vehicles, including autonomous locomotives, using synchronous generators and traction synchronous motors is showed. Typical block diagram of electric transmission of traction rolling stock and functional diagram of electric power transmission with synchronous generator and traction motors are given. Based on the theory of a generalized electrical motor, a mathematical description has been devel-oped in a two-phase coordinate system for a synchronous generator with excitation winding and starting winding and a synchronous motor with permanent magnets, its equivalent schemes are shown. The results of simulation in Matlab Simulink of electric system with two traction motors connected to frequency converters with two-level voltage source inverters are given. Direct torque control system with a table function of switching the voltage source inverter by output signals of relay regulators of torque and flux linkage is used for motor control. Based on the obtained re-sults, recommendations for the synthesis of energy-efficient control systems for synchronous motors with permanent magnets are given

Modified modeling and internal model control method of thrust ripples in PMLSMs for ultraprecision air-bearing linear feed systems

With the aim of attenuating thrust ripples in ultraprecision air-bearing linear feed systems, a simple and effective internal model control (IMC) system is herein presented based on a modified modeling and identification method of permanent magnet linear synchronous motors (PMLSMs). First, flux linkage equations were used to describe the volt–ampere characteristics of PMLSMs and provide a thrust expression in a differential form based on the principle of virtual work. Then, an analytical formula was obtained through derivation based on the condition of field-oriented control. On this basis, an IMC compensator was designed using an inverse model to attenuate nonlinear thrust effects, and an extended Kalman filter (EKF) was adopted to estimate the actual current in an analog linear amplifier. The boundedness of the nonlinear system was analyzed based on the convergence condition; furthermore, the stability of the proposed IMC compensator with EKF could be guaranteed. Then, an accurate model and thrust parameters were obtained using an identification experiment on an air-bearing linear platform driven by a linear analog amplifier. To demonstrate the coupling effect of current on thrust and confirm the effectiveness of the proposed method, both simulations and experiments were performed at a uniform velocity under extra loads of different weights; then, an extended state observer (ESO) was introduced as a comparative method. Finally, the results of the following error indicated that the proposed method demonstrated improved performance in terms of overcoming the influence of nonlinearity and that it results in smooth velocities in steady states.

Design and Cogging Torque Reduction of Radial Flux Brushless DC Motors with Varied Permanent Magnet Pole Shapes for Electric Vehicle Application

Brushless direct current motors have more attractive features, making them a promising solution for electric vehicle applications. A 1 kW, 510 rpm, 24-slots and 8-pole inner runner type surface permanent magnet mounted radial flux brushless DC motor with seven different permanent magnet pole shape rotor is investigated. Motors with different permanent magnet shape rotors were designed, and finite element modelling and simulation were carried out. For performance comparison, the initial design with a radial-type pole shape was regarded as a reference design. Cogging torque is detrimental to the overall performance of the motor, typically in low-speed applications like electric vehicles. The primary aim of this paper is to reduce the cogging torque &amp; study its effect on the overall performance of the motor and minimize torque ripples with reduced permanent magnet requirements. The proposed designs are analyzed in terms of cogging torque, flux density, torque, efficiency, flux linkage and back-EMF. The comparative analysis shows that the motor with bump-shaped permanent magnet rotor poles has betterperformance than the others.

Quantitative assessment on synchronisation capability of a line‐start permanent magnet synchronous motor with hybrid rotor

AbstractThe authors devote a quantitative assessment on the synchronisation capability of a line‐start permanent magnet synchronous motor (LSPMSM) equipped with a hybrid rotor. The quantitative assessment is realised by determining a load criterion consisting of load torques and inertias under which the motor will just synchronise. During the process of load‐criterion determination, close attention is paid to parameters governing the motor synchronisation behaviour. Following the principle of stator‐current error minimisation, the time‐variant magnetising inductances and permanent magnet (PM) flux linkages of the analysed LSPMSM are simplified into slip‐dependent constants via the simple and robust genetic algorithm (GA). The load criterion is then obtained after the establishment of a dynamic motor model involving the simplified parameters. Prototyping tests focused on motor speed‐time responses under different mechanical loads are carried out to validate the obtained load criterion and the paper analyses.

Neural Network-Driven Sensorless Speed Control of EV Drive Using PMSM

To reduce pollution and energy consumption, particularly in the automotive industry, energy saving is the main concern, and hence, Electric vehicles (EVs) are getting significantly more attention than vehicles with internal combustion engines (IC engines). Electric motors used in Electric Vehicles (EVs) must have high efficiency for maximum utilization of the energy from the batteries or fuel cells. Also, these motors must be compact, lightweight, less expensive and very easily recycled. Further, to obtain better dynamic performance, various motor control strategies are used to control the speed of the motor. And to have increased reliability, sensorless speed control techniques that offer sufficiently high performance are used. The sensorless speed control techniques are largely divided into three groups: state observer methods, indirect measurement methods and saliency-based methods. Generally, the state observer uses back emf or flux linkage to estimate the speed of the motor. Since the back emf is directly proportional to the rotor speed, at low-speed back emf based method will give poor performance. The current-based Model Reference Adaptive System (MRAS) model is also popular for estimating low speed; however, assessments deteriorate during high performance applications such as EV. This paper presents an artificial neural network (ANN)-deployed sensorless speed control of permanent magnet synchronous motor (PMSM) drive used in EVs. In this paper, the estimation of speed using the current-based MRAS model is discussed and compared with the proposed ANN-based controller, which shows significant improvement in the performance of EV motor drives. The MATLAB simulation and experimental results are presented to validate the proposed algorithm.

Optimized FCS-MPCC based on disturbance feedback rejection for IPMSMs under demagnetization fault in high-speed trains

This paper proposes an optimized finite control set model predictive current control (FCS-MPCC) strategy based on disturbance feedback rejection control (DFRC) method for interior permanent magnet synchronous motors (IPMSM) employed in high-speed trains. The strategy aims to mitigate the impact of parameter mismatch caused by permanent magnet demagnetization faults. Firstly, a discrete predicting model is established for IPMSMs, considering the mismatch in flux linkage, resistance, and inductance. The analysis is conducted to evaluate the impact of disturbances caused by demagnetization faults on the traditional FCS-MPCC. Secondly, second-order sliding mode disturbances observers (SMDOs) are utilized to detect real-time disturbances under demagnetization faults. The stability analysis of the second-order SMDOs is conducted using a Lyapunov function. Furthermore, disturbance controllers are developed to regulate the disturbances and generate compensating values for the FCS-MPCC. Lastly, experimental validation is performed on two IPMSMs to demonstrate the effectiveness of the proposed DFRC-based FCS-MPCC strategy against parameter mismatch issues caused by demagnetization faults.

Non-volatile resistive switching behavior and time series analysis of Ag/PVA-graphene oxide/Ag device

Non-volatile memory devices have been getting significant attention from researchers worldwide in recent years due to their application in resistive random access memory and neuromorphic computing. Here, we have fabricated polyvinyl alcohol-graphene oxide (PVA-GO) composite as an active material for the resistive switching with different concentrations of GO (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5 wt. % GO solution) dispersed in 5 wt. % PVA matrix in a 2:1 volume ratio. We demonstrate the non-volatile forming free resistive switching properties of Ag/PVA-GO/Ag devices. Structural properties of PVA-GO composites are established from the x-ray diffraction pattern, which indicates the complete dispersion of GO inside the PVA matrix. The Ag/PVA-GO-0.1 wt. %/Ag device shows better bipolar resistive switching at VSET ∼ 0.4 V and VRESET at ∼−0.8 V. This device indicates well-resolved two distinct states at a read voltage of 0.1 V in endurance and retention measurements. The fabricated device switches successfully tested for 2.5 × 103 cycles and retains its state for 3.36 × 103 s without any observable degradation. Furthermore, the non-volatile retention property was modeled using time series analysis. For this, Holt–Winter's exponential smoothing technique was utilized. Additionally, the charge–flux linkage characteristic shows the double-valued function, and time domain–charge and time domain–flux show asymmetric behaviors. The electrical conduction mechanism exhibits ohmic behavior in the entire region of the low resistance state and the lower voltage region of the high resistance state. In the high-voltage region of the high resistance state, the space charge-limited conduction mechanism is observed. The resistive switching behavior is explained with the help of an appropriate model.

Analysis of an Axial-Flux Slotted Limited-Angle Torque Motor with Quasi-Halbach Array for Torque Performance Improvement

Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors (LATMs), which are primarily used to position first-stage valves in electrohydraulic servosystems. This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range (CTR) and output torque. Firstly, the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed. Secondly, a brief design procedure is presented, the structure selections of open slot and double-stator single-rotor (DSSR) interior rotor with surface mounted quasi-Halbach permanent magnet (PM) array are illustrated, and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM. Then, 3-D finite-element method (FEM) is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque, no-load back EMF, and output torque, and the results show that the proposed LATM with quasi-Halbach array has a 10% improvement in output torque and a 25% improvement in CTR. Meanwhile, the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation. Finally, prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.

Deadbeat-Direct Torque and Flux Control of a Brushless Axial-Flux Magnetic-Geared Double-Rotor Machine for Power-Splitting HEVs

A deadbeat-direct torque and flux control (DB-DTFC) for brushless axial-flux magnetic-geared double-rotor machines (AMGDRMs) is presented in this paper. The AMGDRM is employed as a power-splitting component in hybrid electric vehicles (HEVs) to enable speed decoupling between the internal combustion engine (ICE) and load. Since the rigid connection between the ICE and the drive train is replaced by the AMGDRM, fast torque control of the AMGDRM is required for the ICE speed regulation. Furthermore, the ICE torque contains abundant harmonics, inevitable sinusoidal components are introduced to the modulating rotor torque for torque balance, and further to the PM rotor torque owing to the magnetic-gear effect. Since both the PM rotor of the AMGDRM and the traction motor contribute to the hybrid electric system total torque output (i.e., torque coupling), the cascaded traction motor should compensate the PM rotor torque ripple actively to guarantee smooth total output torque. However, proportional-integral (PI) regulator suffers from limited bandwidth and thus could not realize accurate torque decoupling. Therefore, DB-DTFC, where torque and flux linkage are decoupled and respectively achieve their reference commands within two sampling periods, i.e., deadbeat responses, is proposed to enable a faster and more robust ICE speed control and accurate torque decoupling. The DB-DTFC law is derived and discrete-time close-loop current and flux linkage observers of the AMGDRM are developed. The proposed scheme and its superiorities are experimentally validated on an AMGDRM prototype test bench.

3D Hybrid Segmented Layer Modeling of On-Load Magnetic Fields and Torques for Coreless Axial-Flux Permanent Magnet Synchronous Motor

This paper presents a novel 3-dimensional hybrid segmented layer model (3D HSLM) for coreless axial-flux permanent magnet synchronous motors (AFPMSMs). In the proposed 3D HSLM, the magnetic field sources are divided into the PM array and current-driven electro-magnets, which are captured by the combination of the magnetic scalar potential and vector potential models. This paper proposes a geometry function and cylindrical harmonic index modulation functions in order to correctly capture the curvature effect by the PMs and coils with arbitrary shapes and also the radial edge effect from the finite lengths of the rotor and the stator. The proposed modeling method also enables accurate estimation of the motor characteristics on the on-load conditions using the magnetic vector potential model. The fidelity of the proposed 3D HSLM is validated against the equivalent FEM models for various cases with different PM and coil shapes, in terms of the airgap magnetic fields, motor torque, and flux linkage. The comparison results show that the proposed 3D HSLM yields a modeling accuracy of more than 98% while significantly reducing the calculation time by two orders of magnitude as compared to the FEM models.

Sensorless vector control approach for the interior PM synchronous machine with DC-offset compensation loop

Two different DC offset compensators for sensorless PMSM, motor drives with wide speed range flux linkage observers, are introduced and compared. The first one is an improved flux observer with PI correction and no need for mover speed and phase adaptation. The second one is a novel flux observer with an active disturbance rejection controller (ADRC) compensator without mover speed adaptation. The ESO built into ADRC is able to detect and compensate for both internal model disturbance and external load disturbance, resulting in a controller with superior dynamic responsiveness and robust regulation. In both scenarios, an injected direct current (DC) offset is calculated and maintained by the PI integral part and ADRC, which effectively compensates for the DC biases and drifts caused by the sampling channels. Compared to the PI controller, ADRC demonstrates greater transient performance and disturbance robustness. The results of theoretical analysis and Matlab simulations have confirmed the feasibility and efficiency of the proposed strategy.