Optimal Rotor Research Articles

Optimal Rotor Design of an 150 kW-Class IPMSM by the 3-D Voltage–Inductance-Map Analysis Method

A method is presented to determine the detailed design of a 150 kW-class interior permanent-magnet synchronous motor. The basic designs of stator and rotor were determined, after dividing the designed models into the best and worst cases on the basis of the rotor-shaped parameters. First, the three-bridge basic model satisfying the structural (mechanical) safety factor of the rotor is proposed. The three-bridge basic model does not meet the required torque at rated and maximum speed compared to the no-bridge model. Therefore, it is necessary to perform the design analysis through the selection of various design parameters. However, it is hard and takes alot of time to perform an analysis with numerous shape parameters. Therefore, design parameters with the greatest effect on torque and induced voltage are found using the sensitivity analysis. And the 3-D voltage–inductance map parameters were analyzed. Then, the design of the final model was predicted. On the basis of this prediction, the final model was extracted with a trend analysis. Finally, the final model was validated with experiments.

Aerodynamic performance optimization for the rotor design of a hovering agricultural unmanned helicopter

The importance of using Agriculture unmanned helicopters (AUHs), especially for spraying pesticides and fertilizers on any terrain type to ensure crop yields, has been recently acknowledged. Apart from flying these helicopters at a super-low altitude and low speed, using an efficient and optimum rotor blade ensures a uniform and deep penetration of pesticide and fertilizers over a specified area. Accordingly, this work attempts to optimize the rotor blade of an AUH by using coupling statistics and several numerical techniques, including design of experiments, response surface method, and computational fluid dynamics. The experiments are designed using the central composite design method and by selecting the geometric variables that affect the aerodynamic performance of the rotor blade, including the root chord, tip chord, and angle of attack. The angle at the root and tip is optimized in order for the resulting twist to produce a uniform blade loading, achieve maximum lift, and minimize the required hover power. The required aerodynamic forces and limited availability of engine power are identified as constraints. The blade is optimized only when the helicopter is hovering at a persistent rotational speed, and the hover efficiency of the rotor blade with an optimal twist distribution is significantly higher than the baseline.

Tip Loss Factor Effects on Aerodynamic Performances of Horizontal Axis Wind Turbine

Abstract: Tip loss corrections are an important factor in Blade Element Momentum (BEM) theory when determining optimum blade design for maximum power production. This paper presents the optimal tip design using the new tip loss correction. A semi-analytical solution was proposed to find the optimum rotor considering Shen’s new tip loss model. The optimal blade geometry is obtained for which the maximum power coefficient is calculated at different design tip speed and glide ratio. Our simulation is conducted for S809 rotor wind turbine blade type, produced by National Renewable Energy Laboratory (NREL).

Levitation Force Maximization in HTS Magnetic Bearings Formulated by a Semianalytical Approach

High-speed rotatory electromechanical devices can be practically implemented using magnetic bearings that provide a contactless operation. Besides the contactless operation, high-temperature superconducting (HTS) bearings possess an exclusive feature, i.e., self-stability. This characteristic removes requiring any control schemes and consequently an easier implementation and lower costs would be expected. This paper deals with presentation of an optimal rotor configuration in radial-type HTS bearings. A semianalytical approach called Adomian decomposition method is used to efficiently solve the governing equations of HTS bearings deduced from the H-formulation combined with the E-J power law. Control variables of the optimization process include rotor dimensions as well as magnetization direction of permanent magnets. Optimization is carried out using a powerful approach called differential evolution with maximization of levitation force around the equilibrium position as its objective function. In order to verify the proposed approach, a two-dimensional axisymmetric finite element method is also implemented.

Adaptive neuro-fuzzy algorithm to estimate effective wind speed and optimal rotor speed for variable-speed wind turbine

The precise measurement of effective wind speed is a crucial task and has huge impact on wind turbine output power, safety and control performance. In this study, a hybrid intelligent learning based adaptive neuro-fuzzy inference system (ANFIS) is proposed for online estimation of effective wind speed from instantaneous values of wind turbine tip speed ratio (TSR), rotor speed and mechanical power. The artificial neural network (ANN) adjusts the parameters of fuzzy membership functions (MFs) using hybrid optimization method. The estimated value of effective wind speed is further utilized to design the optimal rotor speed estimator for maximum power point tracking (MPPT) of variable-speed wind turbine (VSWT). Both estimators are implemented in MATLAB and their performance is investigated for national renewable energy laboratory (NREL) offshore 5 MW baseline wind turbine. The simulation results show the effectiveness of proposed method. The proposed scheme is computationally intelligent, easy to implement and more reliable for fast estimation of effective wind speed and optimal rotor speed.

A Novel Modular-Stator Outer-Rotor Flux-Switching Permanent-Magnet Motor

A novel modular-stator outer-rotor flux-switching permanent-magnet (MSOR-FSPM) motor is proposed and studied in this paper. Structure, operation and design principles of the MSOR-FSPM motor are introduced and analyzed. Considering that the combination of different pole number and slot number has a great influence on the motor performance, the optimum rotor pole number for the 12-stator-slot MSOR-FSPM motor is researched to obtain good performance and make full use of the space in the MSOR-FSPM motor. The influences of rotor pole number on cogging torque, torque ripple and electromagnetic torque are analyzed and a 12-slot/10-pole MSOR-FSPM motor was chosen for further study. Then, several main parameters of the 12-slot/10-pole MSOR-FSPM motor were optimized to reduce the torque ripple. Finally, the utilization of permanent magnet (PM) in the MSOR-FSPM motor and a conventional outer-rotor flux-switching permanent-magnet (COR-FSPM) motor are compared and analyzed from the point of view of magnetic flux path, and verified by the finite element method (FEM). The FEM results show that the PM volume of MSOR-FSPM motor is only 54.04% of that in a COR-FSPM motor, but its average electromagnetic torque can reach more than 75% of the torque of COR-FSPM motor.

Optimal Rotor Design of Line Start Permanent Magnet Synchronous Motor by Genetic Algorithm

Optimal Rotor Design of Line Start Permanent Magnet Synchronous Motor by Genetic Algorithm

Maximum Wind Energy Extraction for Variable Speed Wind Turbines With Slow Dynamic Behavior

Currently, the maximization of wind energy extraction for variable speed wind turbines (VSWT) is usually transformed into the maximum power point tracking (MPPT), i.e., the rotor speed is continuously regulated to follow the optimal rotor speed as a function of wind speed. However, it has been recognized that the increasing rotor inertia and the high fluctuation of wind speed result in the turbines’ being unable to instantly track the optimal rotor speed and tracking losses. This indicates that maximizing wind energy extraction based on MPPT is not suitable for large-inertia VSWTs under turbulence. Moreover, it is revealed and demonstrated in this letter that a conservative speed reference matching up with the slow dynamic behavior of VSWTs can effectively improve wind energy production, which provides a new approach for maximizing wind energy extraction of VSWTs under turbulence.

Multidisciplinary Aerodynamic Design of a Rotor Blade for an Optimum Rotor Speed Helicopter

The aerodynamic design of rotor blades is challenging, and is crucial for the development of helicopter technology. Previous aerodynamic optimizations that focused only on limited design points find it difficult to balance flight performance across the entire flight envelope. This study develops a global optimum envelope (GOE) method for determining blade parameters—blade twist, taper ratio, tip sweep—for optimum rotor speed helicopters (ORS-helicopters), balancing performance improvements in hover and various freestream velocities. The GOE method implements aerodynamic blade design by a bi-level optimization, composed of a global optimization step and a secondary optimization step. Power loss as a measure of rotor performance is chosen as the objective function, referred to as direct power loss (DPL) in this study. A rotorcraft comprehensive code for trim simulation with a prescribed wake method is developed. With the application of the GOE method, a DPL reduction of as high as 16.7% can be achieved in hover, and 24% at high freestream velocity.

Optimization Design and Experimental Study of a Two-disk Rotor System Based on Multi-Island Genetic Algorithm

Abstract Based on rotor dynamics theory, a two-disk flexible rotor system representing an aero-engine with freely supported structure was established with commercial software ANSYS. The physical model of the two-disk rotor system was then integrated to the multidisciplinary design optimization software ISIGHT and the maximum vibration amplitudes experienced by the two disks when crossing the first critical speed were optimized using a multi-island genetic algorithm (MIGA). The optimization objective was to minimize the vibration amplitudes of the two disks when crossing the first critical speed. The position of disk 1 was selected as the optimization variable. The optimum position of disk 1 was obtained at the specified constraint that the variation of the first critical speed could not exceed the range of ±10 %. In order to validate the performance of the optimization design, the proof-of-transient experiments were conducted based on a high-speed flexible two-disk rotor system. Experimental results indicated that the maximum vibration amplitude of disk 1 when crossing the first critical speed declined by 60.9 % and the maximum vibration amplitude of disk 2 fell by 63.48 % after optimization. The optimization method found the optimum rotor positions of the flexible rotor system which resulted in minimum vibration amplitudes.

Influence of Covariance-Based ALS Methods in the Performance of Predictive Controllers With Rotor Current Estimation

The use of online rotor current estimators with predictive current controllers has been very recently stated in five-phase induction motor drives, where the closed-loop performance of the system is improved by using suboptimal estimators based on Kalman filters. In this paper, the interest of using optimization methods in the definition of the Kalman filter, like the covariance technique, is analyzed. Obtained system performances using optimal and suboptimal rotor current estimators are experimentally compared.

Real time induction motor efficiency optimization

The induction machine efficiency optimization issue is the subject of many contributions in the literature. Few solutions, have shown interest in the rapidity-stability dilemma regarding the presence of sudden load torque variations. This paper presents a new useful hybrid approach for efficiency optimization of the direct vector-controlled induction motor drives. The efficiency improvement approach consists of adjusting the rotor flux with respect to the load torque in order to minimize total losses in the induction machine. The optimal rotor flux is defined in two steps. Firstly, the controller defines a suboptimal operating point by a fast analytical algorithm based on the model of induction machine. The suboptimal flux helps to minimize the size of possible solutions space of the optimization issue. The global optimal flux is achieved in the second step using a simulated annealing method. This latter adjusts the flux level in order to reduce the power input at its minimum. This choice overcomes the influence of parameters uncertainty on the controller stability. The proposed controller has been experimentally tested and validated on a 3 kW squirrel age induction motor.

STATISTICAL OPTIMIZATION OF FREQUENCY REGULATED INDUCTION ELECTRIC DRIVES WITH SCALAR CONTROL

Purpose. Working out of technique of synthesizing statistically optimal controllers of induction electric drives with frequency scalar control operating under stochastic loads. Methodology. It is shown, that one of the ways of increasing the energy efficiency of induction electric drives at random changes of loads is to create closed systems of electric drives with statistically optimal regulators that would take into account the stochastic nature of the disturbances and acted as filters of occasional high frequency fluctuations. The structure of such controls depends on the statistical characteristics of stochastic loads – correlation function and spectral density. In this mode, the minimum loss in dynamic mode with random intensive changed loads is provided by criterion of minimum mean square error of optimal parameter control. In the case of frequency controlled electric drive such a parameter is the optimum rotor flux. Results. The optimal structures of regulators of electric drives under stochastic loads according to type of random disturbances are identified. Originality. The technique of statistically optimal synthesis with feature of the expansion of a random process load on average, served as a useful signal, and high-frequency fluctuations around the average value, served as barrier, is developed. Practical value. On an example of simulation of work of the electric drive of a crusher of grain it is shown efficiency of a filtration by statically optimal regulator of the high-frequency components of random torques of load, reduction of dispersions of its outlet parameters, increase of cyclic indicators of energy efficiency of the electric drive, such as cyclic efficiency and power factor.

静止スラストを最大とするロータ設計法

In this paper, the practical design method of the maximum static thrust rotor based on the vortex method is described. After the vortex method is introduced, the simplified optimum rotor design method is presented. By analyzing the shape of the rotor wake, it was evident that the pitch of the vortices produced by the tip of the rotor is half that of the inboard vortices. The wake contraction rate parameter and axial vortex trajectory parameters are obtained from the tip vortices simulation. The accurate design method based on the vortex method with accurate wake model is then executed. The obtained maximum thrust rotor satisfies the conditions required on the Trefftz plane, which is not unfulfilled achieved by the simplified design method.

Optimal active and reactive power control of wind turbine driven DFIG using TLBO algorithm and artificial neural networks

This paper investigates the optimal active and reactive power control capabilities for typical wind turbine (WT) driven doubly fed induction generator (DFIG). The main objective is to determine the optimal rotor voltage to extract certain active and reactive power from the DFIG over wide ranges of wind speed. Teaching learning-based optimisation (TLBO) algorithm is a new heuristic optimisation technique, used to obtain the optimum rotor voltages to achieve reference active and reactive powers overall operating points. Artificial neural network (ANN) controller is used as an adaptive controller to predict the value of rotor voltage for all operating points. The ideal power curve of a 2 MW wind turbine has been estimated to design the active power controller. The stator reactive power control capability with the range of ±1.6 MVAR is developed. With the proposed control strategy, the DFIG-based wind farm provides maximum power point tracking (MPPT), fully active and reactive powers control. For all operated wind speeds, the adaptive proposed controller develops useful network support compared to the conventional DFIG-based wind farm. The proposed system is developed in MATLAB/Simulink environment.

Novel robust simultaneous estimation of stator and rotor resistances and rotor speed to improve induction motor efficiency

This paper presents a novel method of parallel stator and rotor resistances and rotor speed estimation for robust sensorless induction motor drive. Moreover, the estimated parameters have been used to calculate the optimal rotor flux for improving the motor efficiency. In this scheme, a parallel model reference adaptive system (MRAS) is designed to simultaneous estimation of rotor speed and rotor-stator resistances in order to achieve a high-precise control in a wide range of motor speed. The aim of design of one MRAS for parallel estimation of stator and rotor resistances and rotor speed is to save the implementation cost and to reduce the processes time. Moreover, the stability of the control scheme has been derived based on Popov's criterion to design the adaptation mechanisms. Digital simulation based on Matlab/Simulink is carried out to evaluate the effectiveness of the proposed scheme at different operating conditions. The simulation results demonstrate the effectivity of the proposed scheme at a wide range of speed under load disturbance and parameter variation.

Coordinated Operation Strategy of Wind Farms for Frequency Control by Exploring Wake Interaction

This paper proposes a coordinated wind farm (WF) operation strategy that exploits the wake interaction within a WF. In contrast to the conventional WF operation strategy where each wind turbine (WT) is optimized individually, three operation strategies are suggested: 1) maximization of the WF's power while maintaining WF's rotational kinetic energy; 2) maximization of the WF's rotational kinetic energy while maintaining WF's output power; and 3) a de-loaded strategy whereby the WF's rotational kinetic energy is maximized for a fixed de-loading margin. The three operation strategies are formulated as nonlinear optimization problems and solved in a central WF controller. The optimal rotor speeds and pitch angles are used as reference values in the individual WTs. The optimization results for the three respective operation strategies show that: 1) up to 3% increase in the WF's output power; 2) up to 23% increase in the WF's rotational kinetic energy; and 3) up to 28% increase in the WF's rotational kinetic energy and 8% reserve power while operating the WF in a 5% de-loaded mode with respect to the conventional operation strategy. Time-domain simulations show that the proposed operation strategy noticeably improves the WF's performance in frequency control.

Novel robust simultaneous estimation of stator and rotor resistances and rotor speed to improve induction motor efficiency

This paper presents a novel method of parallel stator and rotor resistances and rotor speed estimation for robust sensorless induction motor drive. Moreover, the estimated parameters have been used to calculate the optimal rotor flux for improving the motor efficiency. In this scheme, a parallel model reference adaptive system (MRAS) is designed to simultaneous estimation of rotor speed and rotor-stator resistances in order to achieve a high-precise control in a wide range of motor speed. The aim of design of one MRAS for parallel estimation of stator and rotor resistances and rotor speed is to save the implementation cost and to reduce the processes time. Moreover, the stability of the control scheme has been derived based on Popov's criterion to design the adaptation mechanisms. Digital simulation based on Matlab/Simulink is carried out to evaluate the effectiveness of the proposed scheme at different operating conditions. The simulation results demonstrate the effectivity of the proposed scheme at a wide range of speed under load disturbance and parameter variation.

Efficient Operation of Wind Turbine with Doubly Fed Induction Generator Using TLBO Algorithm and Artificial Neural Networks

This paper investigates efficient operation of the doubly-fed induction generator (DFIG) considering iron losses with active power control capability for typical wind turbine (WT) system. The control objective is to determine the optimal rotor voltage to extract maximum active power from the DFIG over wide ranges of wind speed with two strategies: maximum efficiency strategy and stator UPF strategy. The Teaching Learning Based Optimization (TLBO) algorithm is used to achieve the above objective. The ideal power curve of a 2 MW wind turbine has been estimated to design the active power controller. Artificial neural network (ANN) controller is used as an adaptive dynamic controller to predict the value of rotor voltage for all operating points for the two case strategies. With the proposed control strategy, the DFIG-based WT provides maximum power point tracking (MPPT), fully power control with two control strategies. The overall WT system with DFIG iron losses consideration with the proposed controller is developed using Matlab/Simulink environment.

Rotor structure design of permanent magnet synchronous generator by topology optimization method using GA

This paper proposes a topology optimization method and rotor structure designs for a permanent magnet synchronous generator based on this method. These described designs enable high output power and less permanent magnet volume. The topology optimization method is a genetic algorithm that considers the clusters and cleaning procedure of material. The optimized rotor has a structure in which the magnet is moved in the direction of rotation, and the output power of the optimized rotor is larger than that of the Prius type generator, in spite of less PM volume.