Model Of Synchronous Reluctance Motor Research Articles

Torque/Speed Control of 3PH Synchronous Reluctance Motor Using Direct Torque Control

This paper presents an investigation of the dynamic performance of the synchronous reluctance motor (SynRM) controlled by the Direct Torque Control (DTC) technique to attain either torque or speed control. The system under study comprises synchronous reluctance motor driving a mechanical load. The inner control loop of the DTC algorithm is employed to achieve torque control through the torque hysteresis comparator in which the command torque is set externally as desired. The speed control is accomplished by adding an outer control loop comprising a speed comparator and PID controller. The controller parameters are accurately tuned to provide high transient and improved dynamic performance of the motor. The SynRM model, in the d-q synchronously rotating reference frame, and the overall components of the DTC algorithm are formulated in MATLAB/Simulink. The transient and dynamic response of the SynRM controlled by DTC is investigated when the overall system is subjected to various patterns of torque and speed commands. The results confirmed that the proposed DTC technique attained a stable, fast, and robust response for both torque and speed control loops of the controlled SynRM. Furthermore, the impact of varying the controller sampling time was explored, the outcomes revealed that as the sampling time reduces, the motor dynamic performance is significantly improved.

Impact of Rotor End Effects on FEM-Based Flux Mapping of Synchronous Reluctance Motors

The paper deals with the accurate flux map modeling of synchronous reluctance motors, using finite element analyses. Non-negligible discrepancies were initially observed by comparing two-dimensional (2-D) finite element method (FEM) simulation results with measured flux maps of real machines. Conversely, the three-dimensional (3-D) FEM-based flux mapping offers more accurate estimation of the aforementioned flux linkage characteristics and gives evidence of the 3-D end effects being also a function of the relative position between the magneto-motive force waveforms of the rotor and the stator. The paper investigates such 3-D end effects for different rotor geometries and winding structures, utilizing 2-D and 3-D FEM analysis in comparison to experimental data. The paper confirms that the 3-D effects are non-negligible both in concentrated and distributed winding machines. A simple mathematical approach is proposed for the concentrated winding machine, capable of off-line correction of the 2-D FEM flux maps. The proposed closed-form equation is validated through 3-D FEM and experiments.

Modeling of a synchronous reluctance machine accounting for space harmonics in view of torque ripple minimization

The paper deals with modeling of synchronous reluctance motor (SynRM) accounting for all phenomena responsible for torque ripple. Based on winding function approach, the proposed model consists in computing self and mutual inductances considering no sinusoidal distribution of stator windings, slotting effect and no sinusoidal reluctance variation caused by the rotor saliency. Then, optimal current waveforms are determined for each rotor position by solving a second order equation to reduce torque ripple. These currents are used within a vector control scheme. Satisfactory agreement between simulation and experimental results is obtained.

Rotor‐design and on‐line starting‐performance analysis of a synchronous‐reluctance motor

PurposeThe purpose of this paper is to derive the geometry‐based equations for inductances which are used in circuit theory analysis of synchronous reluctance motor (SRM). Transient and steady state performance analyze of SRM by using the 2D time‐stepping finite‐element method (FEM).Design/methodology/approachThe analytical approach is used to obtain the equations which describe geometry dependent magnetizing inductances of SRM. Transient and steady state performance of the SRM is analyzed by using the 2D time‐stepping FEM. The external electric circuit connected with the finite‐element model of the SRM geometry allows the study of almost any of the electric and magnetic properties of the machine. Presented SRM model is also connected to the external mechanical loads (friction, rotor inertia and load torque). The use of different materials for the magnetic‐pole part of the rotor and for flux barriers was analyzed. The flux barriers in the first SRM rotor were filled with a pure massive electrically conductive ferromagnetic with a proper B‐H curve, whereas the rotor magnetic segments were made of non‐conductive electric steel described with its B‐H curve. The conductive barriers with their end rings form a squirrel cage and allow SRM to start on‐line. The flux barriers of the second SRM rotor were made of aluminum but between the second and third flux barrier a massive electrically‐conductive ferromagnetic was inserted which during starting‐up acted as a part of the squirrel cage. All of the flux barriers of the third SRM rotor were made of electrically‐conductive aluminum with iron parts axially laminated. The finite‐element SRM models coupled with an electric circuit is also used to evaluate the motor performance at various asynchronous speeds.FindingsAnalytical geometry‐dependant equations for the d‐ and q‐axis SRM inductances are derived. On the basis of the proposed 2D time‐stepping finite‐element analysis, the start‐up performance for the SRM rotor design using different materials is established. The torque distribution as a function of time at any of the observed asynchronous speeds is not smooth and uniform. It consists of the stator‐to‐rotor tooth pulsating torque, and the synchronous and asynchronous component.Research limitations/implicationsThe main disadvantage of analytical geometry‐dependant equations for the d‐ and q‐axis SRM inductances is the linearization of any of the ferromagnetic parts.Practical implicationsOn the basis of the proposed 2D time‐stepping finite‐element analysis, the start‐up performance, asynchronous run and synchronous torque characteristics for the SRM rotor design using different materials are established.Originality/valueThe value of the paper is the closed view about happenings in rotor flux barriers of SRM, mostly regarding the time distribution of induced currents in the rotor flux barriers. On the base of 2D time‐stepping FEM, the use of different materials for the magnetic‐pole part of the rotor and for flux barriers was analyzed.

The Evaluation of Online Observer System of Synchronous Reluctance Motor Using a Coupled Transient FEM and Preisach Model

This study deals with the dynamic characteristics analysis of synchronous reluctance motor (SynRM) using finite element method in which the moving mesh technique is considered. The focus of this paper is to show the appropriate of online observer system for position sensorless control of a SynRM under saturation and iron loss. Comparisons are given with angle of the observer and that of proposed FEM and Preisach model of synchronous reluctance motor, respectively. The position sensorless control system is realized, and the effectiveness of the observer system is verified by experimental results.

A new investigation of dynamic mathematical model of synchronous reluctance motor—A simple unified analysis of model characteristics

AbstractThis paper presents a new characteristics analysis of a dynamic mathematical model for synchronous reluctance motors, which is recently attracting attention in conjunction with the problem of rotor phase selection and estimated based on the extended BEMF (back electromotive force) for sensorless drive. This paper gives the following new characteristic results in a simple unified analytical manner. (1) Change between positive and negative salient pole phases requires basically no modification to the dynamic mathematical model in the general reference frame. (2) Selection of positive or negative salient pole phase as rotor is no more than a preference of designers. (3) There exists a very simple method of deriving two stator flux models for explicit expression of the extended BEMF. (4) At least four circuit equations with the extended BEMF exist, which are equivalent to each other on the same reference frame. (5) There exists duality among the four circuit equations from the viewpoints of rotor phase selection. (6) The duality reinforces the above‐mentioned five results. Main results of this paper correct or reinforce the results recently reported by others. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 69–75, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20244

Numerically efficient steady-state finite-element analysis of magnetically saturated electromechanical devices

We present a numerically efficient steady-state finite-element solver for electromechanical devices incorporating magnetic saturation in which the magnetization of ferromagnetic materials is modeled as a field-dependent equivalent current density. We use a Lagrangian representation of continuum variables, thereby removing numerical instabilities due to the Peclet effect but precluding the use of standard harmonic balance methods. The shooting-Newton method is therefore used to calculate the steady-state behavior. A matrix-free Krylov-subspace linear solver, the generalized minimum residuals method (GMRES), dramatically reduces the computational burden by eliminating the need to calculate the shooting-Newton Jacobian. Simulation results from a synchronous reluctance motor model with 10 288 nodes and 4935 elements confirm that the proposed method requires much less computation time than running transient analysis until convergence.

Magnetically nonlinear and anisotropic iron core model of synchronous reluctance motor

The magnetically nonlinear and anisotropic iron core model of a synchronous reluctance motor (SRM) is presented. The iron core model is given by the current-dependent flux linkages and their partial derivatives. It is included in a dynamic SRM model and confirmed through the comparison of measured and calculated results in the case of current-controlled linear synchronous reluctance servomotor.

Mirror-Phase Characteristics of Synchronous Reluctance Motor and Salient-Pole Orientation Methods for Sensorless Vector Controls

In this paper, first of all a mathematical model of synchronous reluctance motor in a new form is established, secondly a new analysis of stator linkage flux of the motor is given, which characterizes the motor and plays the essential role for developing new rotor salient-pole orientation methods for sensorless vector controls. Finally in a unified manner based on the inherent characteristics of the flux, six new potential salient-pole orientation methods are developed and proposed.

Efficiency-optimized direct torque control of synchronous reluctance motor using feedback linearization

In this paper, a nonlinear controller capable of high dynamic torque regulation and efficiency optimization of the synchronous reluctance motor (SynRM) using input-output feedback linearization is proposed. The cross-coupling effects in the SynRM model and the torque nonlinearity due to the iron losses in torque-speed characteristics of the SynRM are discussed. The criterion for the efficiency optimization is also introduced and investigated. Since the proposed nonlinear controller directly regulates the torque by selecting the product of d- and q-axes torque currents as one of the output variables, the nonlinear and cross-coupling aspects between the d-and q-axes torque currents and the terminal currents can he eliminated. Hence, the linear torque-speed characteristic can be achieved. In addition, by controlling the power loss-minimizing criterion directly, the proposed controller can optimize the efficiency of the SynRM without deteriorating the dynamics performance.