Load Torque Variations Research Articles

Nonlinear Feedback Linearization and Observation Algorithm for Control of a Permanent Magnet Synchronous Machine

The aim of this study is to present a high dynamic current control and speed estimation strategy for Permanent Magnet Synchronous Motor (PMSM) drives without a speed transducer. The strategy is based on the exact linearization methodology and Extended Sliding Mode Observer (ESMO) algorithm. The performances of the proposed control strategy are analysed by simulations for a 1.6 kW PMSM. The obtained results show the effectiveness of the proposed robust current control approach and speed observation algorithm under load torque and stator resistance variation.

Transients of electrical and mechanical quantities of a brushless DC motor - computations, measurements

Transients of electrical and mechanical quantities of a brushless DC motor - computations, measurements The paper presents a method of computing electrical and mechanical variables of BLDC motors. It takes into account electrical, magnetic and mechanical phenomena in the power supply-converter-BLDC motor-load machine system. The solution to the problem is the so-called circuit-field method. The results determined with the use of time stepping finite element method were used as the parameters of equations of the developed mathematical model. Losses in the motor, losses in transistors and diodes of the converter as well as the actual back EMF waveforms, variable moment of inertia and variable load torque are accounted for. The designed laboratory stand and the test results are presented in the paper. The experimental verification shows the correctness of the developed method, algorithm and program. The developed computational method is universal with respect to different electromechanical systems with cylindrical BLDC motors. It can be applied to electromechanical systems with BLDC motors operating at constant but also variable load torque and moment of inertia.

Embedded DSP-Based Compact Fuzzy System and Its Application for Induction-Motor $V/f$ Speed Control

This paper presents a compact embedded fuzzy system for three-phase induction-motor scalar speed control. The control strategy consists in keeping constant the voltage-frequency ratio of the induction-motor supply source. A fuzzy-control system is built on a digital signal processor, which uses speed error and speed-error variation to change both the fundamental voltage amplitude and frequency of a sinusoidal pulsewidth modulation inverter. An alternative optimized method for embedded fuzzy-system design is also proposed. The controller performance, in relation to reference and load-torque variations, is evaluated by experimental results. A comparative analysis with conventional proportional-integral controller is also achieved.

Unambiguous Detection of Broken Bars in Asynchronous Motors by Means of a Flux Measurement-Based Procedure

Different techniques have been developed to detect rotor asymmetries in asynchronous motors. Although the reliability and the amount of information these techniques provide about a machine's state are indubitable, they still have a serious limitation: failure detection when the motor is driving a variable load torque. In this case, the motor phase currents are modulated by torque oscillations, and the information they contain about the integrity of bars and end rings is altered. This paper reports a new diagnostic method, based on the measurement of the magnetic flux linked by one stator tooth, which allows perfect simple discrimination between the actual presence of rotor asymmetries and the spurious effects caused by the oscillations in the load torque off the driven machine even when it is part of an adjustable speed drive and the motor is operating under a variable supply frequency.

영구자석 동기전동기의 퍼지 속도제어기 및 퍼지 각가속도 관측기 설계

This paper proposes a new fuzzy speed controller for the precise speed control of a permanent magnet synchronous motor(PMSM). The proposed control system needs the information of the angular acceleration instead of the load torque, so the third-order fuzzy acceleration observer estimates it. Moreover, the LMI conditions are derived for the existence of the fuzzy acceleration observer and fuzzy speed controller, and the gain matrices of the observer and controller are obtained. It is analytically proven that the proposed observer-based fuzzy speed regulator is exponentially stable. To evaluate the performance of the proposed control algorithm, experimental results as well as simulation results are provided under the conditions of motor parameter and load torque variations. Finally, it is clearly confirmed that the proposed control method can accurately control the speed of a PMSM.

Adaptive speed controller design for a permanent magnet synchronous motor

An adaptive speed controller is proposed for a permanent magnet synchronous motor (PMSM). The proposed adaptive speed regulator is insensitive to model parameter and load torque variations because it does not need any accurate knowledge about the motor parameter and load torque values. The stability of the proposed control system is also proven. Simulation and experimental results are presented to verify the effectiveness of the proposed adaptive speed controller under the uncertainties such as motor parameter and load torque variations using a prototype PMSM drive system.

Digital Implementation of an Adaptive Speed Regulator for a PMSM

We design an adaptive speed regulator for a permanent-magnet synchronous motor (PMSM). The proposed adaptive regulator does not require any information on the PMSM parameter and load-torque values, thus, it is insensitive to model parameter and load-torque variations. We implement the proposed adaptive-speed-regulator system by using a TMS320F28335 floating point DSP. We give simulation and experimental results to verify that our method can be successfully used to control a PMSM under model parameter and load-torque variations.

표면부착형 영구자석 동기전동기의 적응속도제어기 설계

본 논문에서는 표면부착형 영구자석 동기전동기의 속도 제어를 위하여 적응속도제어기를 제안한다. 제안된 적응 제어기는 모터 파라미터와 부하토크의 정확한 정보를 필요로 하지 않으므로 이들의 변동에 매우 둔감하다. 또한 제안된 제어시스템의 안정성을 해석적으로 증명한다. 본 연구에서 제안된 적응속도제어기의 성능을 검증하기 위하여, 모터 파라미터 및 부하토크 변동 하에서 시뮬레이션 및 실험 결과가 주어졌다. 본 결과를 통하여 제안된 속도제어기는 영구자석 동기전동기의 속도를 정확하게 제어할 수 있음을 검증하였다. This paper proposes a new adaptive speed controller for the speed control of a surface-permanent magnet synchronous motor. The proposed adaptive controller is very insensitive to model parameter and load torque variations since it does not require any accurate information on the motor parameter and load torque values. Moreover, the stability of the proposed control system is analytically proven. To verify the effectiveness of the proposed adaptive speed controller, simulation and experimental results are shown under motor parameter and load torque variations. It is clearly validated that the proposed speed regulator can precisely control the speed of permanent magnet synchronous motors.

영구자석 동기전동기를 위한 퍼지 제어기법 기반의 부하 토크관측기에 관한 연구

This paper proposes a new load torque observer based on the Takagi-Sugeno fuzzy method for a permanent magnet synchronous motor(PMSM). A Linear Matrix Inequality(LMI) parameterization of the fuzzy observer gain is given, and the LMI conditions are derived for the existence of the fuzzy load torque observer guaranteeing α-stability and linear quadratic performance. In this paper, a nonlinear speed controller is employed to validate the performance of the proposed fuzzy load torque observer, and various simulation results are presented under motor parameter and load torque variations.

영구자석 동기전동기의 비선형 속도 제어기 및 퍼지토크관측기 설계에 대한 연구

This paper proposes a new nonlinear speed controller with a fuzzy load torque observer based on the Takagi-Sugeno fuzzy method for a permanent magnet synchronous motor(PMSM). The LMI conditions are derived for the existence of the proposed nonlinear speed controller and fuzzy load torque observer, and the LMI parameterization to obtain the gain matrices of the controller and observer is given. In this paper, to verify the performance of the proposed nonlinear speed controller and fuzzy load torque observer, and the simulation and experimental results are demonstrated under motor parameter and load torque variations.

ECAM Control System Based on Auto-tuning PID Velocity Controller with Disturbance Observer and Velocity Compensator

This paper proposed an ECAM (Electronic cam) control system which has simple and general structure. The proposed cam controller adopted the linear and polynomial curve-fitting method to generates a smooth cam profile curve function. Smooth motion trajectory of master actuator guarantees the good performance of slave motion and has an important effect on the interpolation quality of ECAM. The auto-tuning PID velocity controller was applied to overcome the uncertainties in ECAM, and the gains of the controller are updated continuously to ensure the consistency of system performance under varying working conditions. The robustness of system against the varying load torque disturbances and noises is guaranteed by using the load torque disturbance observer to suppress the disturbance on master actuator. The velocity compensator was applied to compensate the degradation of performance of slave motion caused from the varying driving speed of master motion. The stability and validity of the proposed ECAM control system was verified by simulation results.

Wavelet and PDD as fault detection techniques

Motor current signature analysis has been successfully used for fault diagnosis in induction machines. However, this method does not always achieve good results with variable load torque. This paper proposes a different signal processing method, which combines wavelet and power spectral density techniques giving the power detail density as a fault factor. The method shows good theoretical and experimental results.

Design of a Fuzzy Speed Controller for a Permanent Magnet Synchronous Motor

This paper proposes a new fuzzy speed controller based on the Takagi-Sugeno fuzzy method to achieve a robust speed control of a permanent magnet synchronous motor(PMSM). The proposed controller requires the information of the load torque, so the second-order load torque observer is used to estimate it. The LMI condition is derived for the existence of the proposed fuzzy speed controller, and the LMI parameterization to calculate the gain matrices of the controller is provided. It is proven that the augmented control system including the fuzzy speed controller and the load torque observer is exponentially stable. To evaluate the performance of the proposed fuzzy speed controller, the simulation and experimental results are presented under motor parameter and load torque variations. Finally, it is clearly verified that the proposed control method can be used to accurately control the speed of a permanent magnet synchronous motor.

Adaptive backstepping control of a speed-sensorless induction motor under time-varying load torque and rotor resistance uncertainty

A new global adaptive backstepping controller is designed for induction motor speed control based on measurements of stator current and estimation of rotor speed. The designed partial state feedback controller is singularity free and guarantees asymptotic tracking of smooth reference trajectories for the speed of the motor under time varying load torque and rotor resistance uncertainty. The new control algorithm generates estimates for unknown time varying load torque, rotor resistance and rotor speed, which asymptotically tracks and converges to their true values. The rotor flux modulus asymptotically tracks a desired reference signal which allows the motor to operate within its specifications. As in the field-oriented control scheme; the control algorithm generates references for the magnetising flux component and for the speed component of the stator current. The control strategy yields decoupled rotor speed and rotor flux amplitude tracking control goals which allow the selection of an appropriate flu...

Modelling of a car starter with permanent magnet commutator motor

PurposeThe purpose of this paper is to present a developed modelling method of a car starter with permanent magnet commutator motor.Design/methodology/approachMathematical model, algorithm and computational program of electrical and mechanical quantities transients in the system: battery – car starter with permanent magnet commutator motor and planetary gear – combustion engine were developed. Circuit‐field method was applied. Magnetic quantities determined using time‐stepped finite‐element method (with the help of Maxwell software) were used as the parameters of mathematical model equations in circuital part. Program was developed in the Matlab environment.FindingsThe developed mathematical model, the algorithm and the program enable the computations of transients of electrical and mechanical quantities at different ambient temperature, by different swept capacity of the combustion engine as well as by different battery capacity and different charge ratio.Research limitations/implicationsThe analysis was carried out on an example of four‐cylinder combustion engine. However, the developed modelling method can be used for analysis of different combustion engines start‐up.Practical implicationsThe proposed modelling method is useful for analysis of car starters at the stage of design.Originality/valueThe originality of the work consist in the fact that in the developed model variation of the car starter load torque as well as the variations of the entire mechanical system moment of inertia were taken into account.

A Nonlinear Tracking Controller for Voltage-Fed Induction Motors With Uncertain Load Torque

In this paper, a new adaptive output feedback control scheme for the full-order (voltage-fed) model of the induction motor is presented. The proposed algorithm uses measurements of the stator currents and rotor speed and achieves global asymptotic convergence of the rotor speed and flux magnitude to their desired (time-varying) references. The distinguishing feature of the proposed scheme, which makes it appealing from a practical viewpoint, is that it consists of a simple output feedback control law, which is derived using standard arguments pertaining to Hamiltonian systems and passivity-based control. In order to make the scheme robust to load torque variations, an adaptation mechanism is added, which yields asymptotic estimates of the unknown load torque, and a rigorous stability proof for the resulting cascaded closed-loop system is provided. The efficacy of the proposed controller is verified via simulations and experimental tests.

Analysis and Application of Particular Current Signatures (Symptoms) for Cage Monitoring in Nonsinusoidally Fed Motors With High Rejection to Drive Load, Inertia, and Frequency Variations

In this paper, some original and effective fault indicators for broken-bar detection in power squirrel-cage induction motors are presented. A motor phase-current signature analysis can be performed by evaluating the typical ratios I (7 - 2s)f /I 5f and I (5 + 2s)f I 7f, I (13 - 2s)f /I 11 f and I (11 + 2s)f /I 13f , etc., which appear in the phase-current spectrum of faulted motors fed by nonsinusoidal voltage sources. The main advantages of the new indicators are the following: (1) accentuate insensitivity to disturbs such as load torque, drive inertia, and frequency variations; (2) low dependence with respect to machine parameters (except the pole number); and (3) linear dependence on fault gravity. They can be directly applied on motors fed by open-loop low-switching frequency gate turn-off/thyristor converters. Railway traction drives are possible targets. Application to mains-fed motors can be tried too, if suitable harmonics are present in the plant supply. A detailed analytical formulation for fault indicators is furnished, based on the multiphase symmetrical component theory; theoretical results have been supported by experimental work, performed by using a motor with an appositely prepared cage, and successively, method validation was achieved on three other industrial motors.

Robust Rotor Fault Detection by Means of the Vienna Monitoring Method and a Parameter Tracking Technique

The Vienna monitoring method (VMM) is a model-based rotor fault detection method that utilizes the voltage and current models for the computation of a fault indicator. So far, the VMM was investigated with fixed rotor parameters only. In this paper, the parameters of the current model are provided by a parameter tracking technique. For this advanced rotor fault detection method, measurement results are presented for steady-state and varying load torque operations.

Self-Tuning of PI Speed Controller Gains Using Fuzzy Logic Controller

The role of proportional-integral (PI) controller and proportional-integral-derivative (PID) controller as a speed controller for a Permanent Magnet Synchronous Motor (PMSM) in high performance drive system is still vital although new control techniques such as vector control theory that is more effective -but complex- is available. However, PI controller is slow in adapting to speed changes, load disturbances and parameters variations without continuous tuning of its gains. Conventional approach to these issues is to tune the gains manually by observing the output of the system. The tuning must be made on-line and automatic in order to avoid tedious task in manual control. Hence, an on-line self-tuning scheme using fuzzy logic controller (FLC) is proposed in this paper. The performance of the developed proposed controller is tested through a wide range of speeds as well as with load and parameters variations through simulation using MATLAB/SIMULINK. It is found that the proposed 25 rules FLC with adaptive input and output scaling factors enhances the performance of the system especially at high load inertia. The simulation results show that the developed controller can well adapt to speed changes as well as sudden speed reduction besides fast recovery from load torque and parameters variation and these show remarkable improvement compared to conventional PI controller performance.

Adaptive Direct Torque Control of Induction Motors

In direct torque control (DTC), many induction motor parameters are needed, especially those that affect the values of current and flux required in the control algorithm. DTC of induction machines presents an acceptable tracking scheme for both electromagnetic torque and stator flux. This control scheme depends only on stator measurements. The measurement of the stator flux is very difficult to achieve and can be estimated by an observer. The electromagnetic torque and the stator flux (magnitude and angle) can be determined despite their direct dependence on the knowledge of the stator resistance. This resistance can change up to 180% of its nominal value. The resistance changes with the operational conditions of the motor, such as temperature and frequency. Under these circumstances, a parameter identifier is developed to account for the resistance variations, hence establishing adaptive DTC (ADTC). Moreover, load torque represents the changing tasks required from the motor. In this article, the load torque variations are coupled with stator resistance changes, and the effectiveness of ADTC is investigated. More stable motor operations of polyphase induction motors are obtained under these uncertainties using ADTC.