back-EMF Constant Research Articles

Experimental and numerical studies for parameters identification of direct current motor

<p><span>Direct current (DC) motors are widely used in many applications especially those require a speed control, direction and closed-loop control system. In electric vehicle drive system, DC motor is commonly used for the propulsion of low power (<250 W) electric bicycle (e-bike) because it can operate directly from rechargeable batteries with a smart controller. In driving an e-bike in a closed loop control system, it is important to identify and estimate the dynamic of electrical and mechanical parameters. In this paper, the parameters such as armature resistance, armature inductance, back emf constant, torque constant, moment of inertia and viscous friction coefficient are ideally identified using dynamic responses experiments and tests focusing on no load motor and transient input tests. The motor is then modeled in MATLAB/Simulink using the identified motor parameters and its open loop speed and current responses are studied.</span></p>

Design and analysis of hybrid stepping motors with integrated planetary gear trains.

This work presents a novel integrated device that combines a hybrid stepping motor (HSM) and a planetary gear train (PGT) reducer as a compact structural assembly. In this study, a systematic design process was developed to efficiently implement the integrated device. By applying the gear profile on the rotor and the stator, a 9:1 two stages PGT reducer is integrated with a standard 42 type 2-pole stepping motor. The quadratic interpolation method was applied to derive the optimal design of the geometric configurations of the HSM. The electromagnetic characteristics and output performance of the integrated device, including flux linkage, back-emf constant, holding torque, and output torque, were analysed. Finally, the output performance between an existing design and the novel integrated design were compared. The two designs had similar output and holding torque, but the torque ripple was approximately 44.7% lower in the integrated device from 30% to 16.6%. In addition, the axial space arrangement was reduced by 5.2% from 67.7mm to 64.1 5mm, and the torque density was improved by 4.4%.

Finite element modeling and analytic algorithm for electromagnetic performance of Permanent Magnet Synchronous Generator (PMSG) 24 Slot 16 poles from modification of induction motor 0, 75kw 3 Phase

Modification of the induction motor into a permanent magnet synchronous generator is to put a permanent magnet on the squirrel cages stator to generate the magnetic pole as a replacement for the electromagnet pole produced at a separately excitation of the conventional synchronous generator called the Permanent Magnet Synchronous Generator (PMSG). The purpose of this research is to design PMSG by modification of induction motors into permanent magnet synchronous generator with 24 slots 16 pole by using radial flux and utilizing stator. This research is a software-based FEM (Finite Element Method) for design and the magnetic Material used for permanent magnet synchronous generators is Neodymium Iron Boron (NdFeB). The PMSG on this design obtains the back EMF constant for its half-cycle of 4.902 rad/s and gets a voltage of 191.455 Vdc at 375 rpm speed and when given the loading of 100 Ω at 375 rpm speed produces a voltage of 176.73 Vdc, the current of 1.77 A and the output power is 313.24 Watt with efficiency reaching 85%. The PMSG modelling is done to have a specification of 24 slots 16 poles, changes the the characteristic Induction motor with synchrounous speed of 1500 rpm becomes as low as 375 rp. So This PMSG modification can be used as wind turbine or microhydro power palnt with low speed prime mover energy.

Implementation and Experimental Validation of Ultrahigh-Speed PMSM Sensorless Control by Means of Extended Kalman Filter

This article presents an experimental validation of the implementation of a sensorless control algorithm for an ultrahigh permanent magnet synchronous motor by means of an extended Kalman filter, up to 240 000 rpm. The considered application is the air compressor for a fuel cell in an electric car. It is shown that the extended Kalman filter can be used for the ultrahigh-speed drives, without any loss in accuracy and robustness. Proper experimental results are shown regarding the rotor position accuracy and dynamics of accelerations. The extendibility of the presented algorithm to different machines is shown by its implementation with nine different motors. In this article, additional aspects, such as the sensitivity of the algorithm toward changes in the back EMF constant and the impact of temperature variations, are considered.

Robustness to Large-Scale Mass Production Manufacturing Tolerances by Means of Sensitivity and Statistical Analysis for IPMSMs

This article deals with highlighting some pragmatic approaches for determining the key-parameters that one has to monitor in order not to jeopardize the fulfillment of the customer specifications, due to the tolerances, that occur in large-scale mass production. For that, two parametrization models (symmetric vs. asymmetric) and two types of parameter distributions (uniform vs. normal) are compared when considering lamination, stack assembly and material properties tolerances. Results in different scenarios for both the motor (in open-circuit and under load), and the whole drive (with and without position sensor detection errors) are provided and compared with end-of-line measurements (where available) for a 12-slots 10-poles IPM-type PMSM with fractional slot concentrated winding. After including the effect of the temperature in the full asymmetric model, rather good agreements between calculations and measurements are reported for back-EMF and torque constant. Furthermore, it is shown that the interaction between the uncertainties of the motor parameters and the rest of the drive's components (e.g. position sensor) cause large inaccuracies into the system, and they are hardly predictable by taking the individual deviations separately. Finally, towards the end, attempts are made to reduce the computational and the modeling effort using various techniques and ultimately fitted artificial neural networks (ANNs) as surrogates.

Development of a new moving magnet linear compressor. Part A: Design and modeling

Abstract This article provides a detailed design and a CAD model of a new moving magnet linear compressor for the household refrigerator. A comprehensive electromechanical analytical model is provided to quantify the dynamic parameters necessary for the estimation of a compressor's performance. Additionally, the frequency response functions of the prototype at different input power conditions are investigated in order to evaluate the effect of excitation frequency on the dynamic parameters. The developed compressor is rigorously evaluated on a test-rig to validate all the presented analytical models. This article also provides a methodology to calculate the actuator's back-emf and motor constant which performs a vital role in the analytical model developed for any linear compressor. Furthermore, performance of the proposed compressor is evaluated with R600a to validate the pressure–volume curves and frequency response functions.

Combined Sensor–Sensorless Control of PMDC Motor for HD Camera of Unmanned Monitoring System

This paper presents a position control scheme for a high-definition serial digital interface (HD-SDI) camera of an unmanned monitoring system. A combination of both sensor and sensorless algorithms of a permanent magnet (PM) DC motor is proposed to create smooth camera movements, stop it at desired positions, and obtain high-quality images without shaking. The back EMF of the motor can be estimated and its actual speed can be calculated accurately by using a model reference adaptive sensorless (MRAS) method. A low-resolution hall sensor is used to approximate the speed instead of measuring the actual value. The moving position can be estimated from the speed approximation and it can be used together with a sliding mode observer to modify the back EMF constant. In the advanced position control of the camera, both instantaneous speed and moving position references are determined by the acceleration and deceleration speed patterns to satisfy the dynamic response during operation. Furthermore, the instantaneous position error can be compensated by incorporating a speed reference. The effectiveness of the proposed control scheme was verified through experiments.

Mathematical model’s parameters identification in a prototype of solar panel’s motor

Solar panel can optimally convert energy when its position is upright to the sun, thus the innovation of solar tracker is needed. Solar tracker needs a motor so that the solar tracker is able to track the sun. This research studies a motor of solar panel prototype called motor DC. This research identifies parameter value of motor DC mathematical model. Identification is performed on resistance (Ra), inductance (La), back emf constant (Kb), torque constant (Km), rotor inertia (J), coefficient of viscous friction (B). Furthermore, simulation is applied to motor DC mathematical model with the identified parameter. Simulation is repeated 4 times with combinations of back emf constant and torque constant. Result of the simulation system is angular velocity. Then, angular velocity from simulation is compared to the result of angular velocity from the experiment. Comparison indicates that the third simulation shows the best value with the confidence level of absolute average relative deviation of 97.317587123%.

MAGNETOSTATIC FIELD ANALYSIS OF DC COMMUTATOR MOTORS WITH GEAR-TEETH ON THE ROTOR

This paper presents the open-circuit magnetostatic field analysis of a DC commutator motor by applying 1-D and 2-D equivalent magnetic circuit methods. For the 1-D and 2-D equivalent magnetic circuit method, the average air-gap flux density of a DC commutator motor and magnetic flux in every node are derived respectively, and the validity is verified by the finite-element analysis. The Carter’s coefficient is applied to model the permeance of the slot and gear-teeth space. The differences of the air-gap flux density are 3.21% and 3.06% for 1-D and 2-D methods, respectively. The flux linkages, back-EMF constants, cogging torques, electromagnetic torques, and torque ripples of the two gear profiles with feasible number of teeth integrated on the rotor are analyzed to verify the effects of gear profiles. The result shows that the gear-teeth integrated on the motor act as dummy slots, which reduce the cogging torque and torque ripple by 92.02% and 50.14 %, respectively.

PMDC Motor Parameter Estimation Using Bio-Inspired Optimization Algorithms

The precise estimation of the motor parameter is essential to design the appropriate controller. The main goal of this paper is to estimate the parameters of permanent magnet dc (PMDC) motor used in a wheelchair, applying standard as well as a dynamic particle swarm optimization (PSO), ant colony optimization (ACO), and artificial bee colony (ABC) along with experimental methods. The electromechanical, mechanical, and electrical parameters, such as torque constant, back-emf constant, moment of inertia, viscous friction coefficient, armature inductance, and resistance are estimated using both the experimental and optimization methods. The motor is modeled in Matlab/Simulink R2015a using the estimated motor parameters and studied the performance with different loading conditions starting from no-load to full-load. The simulated results of motor performance with estimated parameters are compared with the experimental load test results. The results showed that the PMDC motor parameters estimated from dynamic PSO with varying inertia weight as well as ABC algorithm have comparatively very less speed and current error than standard PSO, dynamic PSO with constant inertia weight, and ACO algorithms. Furthermore, parameters from dynamic PSO with varying inertia weight showed speed as well as current error less than 0.5%, and the ABC algorithm shown current error slightly more than 0.5%. However, the analysis of variance tests shown no significant difference in current and speed performance with parameter estimated from ABC and dynamic PSO with varying inertia weight. Furthermore, ABC algorithm convergence is faster than dynamic PSO with varying inertia weight. But parameters estimated from dynamic PSO with varying inertia weight are precise and may be appropriate for the design of the motor controllers.

유한요소법을 이용한 서비스 로봇관절용 외전형 BLDC 모터설계에 관한 연구

This s paper presents characteristics Analysis of Outer Rotor type BLDC Motor. To reduce the cogging torque and to make the high back EMF constant of the motor, Not only magnetization directions of a permanent magnet are investigated, but also a tooth chamfer of a stator is optimized. The design and analysis results are verified with experimental results.

해석적 방법을 이용한 3상 집중권 권선을 갖는 양측식 슬롯리스 고정자 Halbach 배열 영구자석 선형 발전기의 특성해석

This paper deals with the generating characteristic analysis of permanent magnet linear generator (PMLG) with double-sided Halbach magnet array mover and three phases concentrated stator windings by using analytical method. On the basis of a magnetic vector potential and Maxwell’s equations, governing equations are obtained, and magnetization modeling for Halbach magnet array is performed analytically by using the Fourier series. And then, we obtain electrical parameters such as back-EMF constant, resistance, and coil inductance based on magnetic field calculations. Finally, analytical results for generating performance are confirmed by comparing with finite element analysis results.

해석적 방법을 이용한 양측식 선형 영구자석 발전기의 특성해석

This paper deals with characteristic analysis of double sided permanent magnet linear generator using analytical method. We derived magnetic field solutions produced by permanent magnet and armature reaction based on the 2D polar coordinate and magnetic vector potential. based on the derived magnetic field solutions, Induced voltage is obtained when arbitrary sinusoidal input condition. In addition, electrical parameters such as back-EMF constant, resistance, and inductance are obtained. Finally, generating performance characteristic at the rated load and various load is examined by using equivalent circuit.

역기전력 추정법을 이용한 브러시리스 직류 전동기의 홀센서 상전류 전환시점 보상 방법

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

Analysis of Permanent Magnet Synchronous Generator for Vortex Induced Vibration Hydrokinetic Energy Applications Based on Analytical Magnetic Field Calculations

This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.

Research on Permanent Magnet Linear Synchronous Motor with a Special Pole Shape Based on Finite Element Analysis

In this paper, a model of unit motor (16p15s) which is used for vertical elevator has been set up. And a modification of the primary geometry has been presented. In the new geometry, pole shoes are affixed to the primary poles. The finite element analysis (FEA) of various width of pole and different width of pole shoe have been carried out in this paper. The results show that the force profile of the proposed PMLSM has been improved. The minimum force ripple occurs in a suitable width of the pole shoes. And the back EMF constant is analyzed, too.

Electromagnetic Performance Analysis of Wind Power Generator With Outer Permanent Magnet Rotor Based on Turbine Characteristics Variation Over Nominal Wind Speed

In this paper, we investigate the electromagnetic performance of wind power generators with outer permanent magnet rotors on the bases of variations in the turbine characteristics over nominal wind speeds by employing various proposed analytical techniques. We have employed an electromagnetic analytical method for calculating electrical parameters such as back EMF constant, synchronous inductance, and phase resistance on the basis of the magnetic field distribution calculated in previous studies. Moreover, curve fitting and finite element methods have been used for core losses analysis, while the d-q model employing the coordinate transformation theorem has been used for analyzing generation performances. To validate our techniques, we compared the performance results obtained using our analytical methods with those obtained by experimental setups. In addition, we propose optimized wind turbine characteristics for our model from the analysis results of electromagnetic performances obtained by considering three types of turbine characteristics.

Analysis on electric power consumption characteristics of cylindrical linear oscillatory actuator with Halbach permanent magnet array mover under electromechanical resonance frequency

This paper deals with electric power consumption characteristics of cylindrical linear oscillatory actuator with Halbach permanent magnet array mover under electromechanical resonance frequency. The control parameters such as back-emf constant, torque constant, resistance, and inductance are obtained from characteristic equations and experimental results. Then, the voltage equation and mechanical motion equation after deriving control parameters are proposed by impedance modeling considering mechanical component, and theoretical resonance frequency is predicted by impedance modeling. Finally, dynamic simulation and experimental results are presented for drive characteristics such as current, power factor, and displacement according to the various values of frequency, and this paper find that the current and electric power consumed in linear actuator have the minimum value at the resonance frequency.

Design and Operation of Interior Permanent-Magnet Motors With Two Axial Segments and High Rotor Saliency

Skewing the magnets in a brushless interior permanent-magnet motor can be difficult. One method to overcome this problem is to use axial segments that are rotated (“twisted”) with respect to each other. Compared to other methods of rotor skewing, this method may reduce manufacturing cost and the complexity of the rotor. This paper addresses the use of two axial segments and the associated effects on the back-electromotive force (EMF) waveform and motor performance. The back-EMF waveforms of an interior permanent-magnet motor are deeply influenced by the tooth-slot and winding harmonics. They should be sinusoidal to reduce torque ripple for ac motor servo drives and other applications where smooth operation is required. In the paper, we present the two-segment rotor structure together with a simple technique for reducing high-order back-EMF harmonics, and we derive the optimal twisted angle of the proposed two-segment rotor. This minimizes the total harmonic distortion of the back-EMF waveform due to tooth-slot effects. We examine cogging torque and the reduction in cogging torque. We apply the twisted angle rotor to two different compressor motors. In addition to the back-EMF, we address the torque ripple under load and the effect of twist on back-EMF constant. We examine the results using finite-element analysis and validate them by experimental measurement.

In-Depth Study of the Torque Constant for Permanent-Magnet Machines

The torque constant, together with the back-EMF constant, was originally used in permanent-magnet DC commutator (PMDC) motors to couple electric circuit equations with mechanical equations. It is still an open question how these two constants should be defined in brushless DC (BLDC) motors and permanent-magnet (PM) AC motors. We present an in-depth study of these two constants, and conclude that the definition based on the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> axes is applicable for the dynamic motion control of not only PM AC motors, but also BLDC motors.