Khaled Yahia

Induction motors airgap-eccentricity detection through the discrete wavelet transform of the apparent power signal under non-stationary operating conditions

Fast Fourier transform (FFT) analysis has been successfully used for fault diagnosis in induction machines. However, this method does not always provide good results for the cases of load torque, speed and voltages variation, leading to a variation of the motor-slip and the consequent FFT problems that appear due to the non-stationary nature of the involved signals. In this paper, the discrete wavelet transform (DWT) of the apparent-power signal for the airgap-eccentricity fault detection in three-phase induction motors is presented in order to overcome the above FFT problems. The proposed method is based on the decomposition of the apparent-power signal from which wavelet approximation and detail coefficients are extracted. The energy evaluation of a known bandwidth permits to define a fault severity factor (FSF). Simulation as well as experimental results are provided to illustrate the effectiveness and accuracy of the proposed method presented even for the case of load torque variations.

Induction Motors Broken Rotor Bars Diagnosis Through the Discrete Wavelet Transform of the Instantaneous Reactive Power Signal under Time-varying Load Conditions

Abstract—In this article, a method based on the application of the discrete wavelet transform to the instantaneous reactive power signal, for diagnosing the occurrence of broken rotor bars in induction motors operating under time-varying load conditions, is presented. This method is based on the decomposition of the instantaneous reactive power signal, from which wavelet approximation and detail coefficients are extracted. The energy evaluation of known bandwidths permits to define a fault severity factor. This method has been tested through the simulation of an induction motor using a mathematical model based on the winding-function approach. These simulation results are complemented by experimental tests conducted on an induction motor with several faulty rotors that can be interchanged and both simulation and experimental results have shown the effectiveness of the proposed method for broken rotor bars diagnosis in induction motors even under time-varying load conditions.

The Use of the Modified Prony’s Method for Rotor Speed Estimation in Squirrel-Cage Induction Motors

It is well known that rotor speed estimation assumes a paramount importance for the correct diagnosis of bearings, air-gap eccentricities, or rotor bar defects. In this paper, a new technique for rotor speed estimation using a modified Prony’s method is proposed. The algorithm developed for this purpose is based on tracking the frequencies of the rotor slot harmonics (RSH) that exist in stator currents of most squirrel-cage induction motors. High-order RSH frequencies are used to avoid the possible effect of harmonics stemming from other sources. The proposed modified Prony’s method shows a great ability for tracking RSH frequencies and then the rotation speed. In addition, this technique can deal with noisy and nonstationary signals and it requires only few data samples, which reduce considerably the computational time and data storage requirements. Consequently, the proposed algorithm is suitable for online implementation. The method’s effectiveness is verified by simulation and experimental tests.

Sensorless fuzzy sliding mode control for permanent magnet synchronous motor fed by AC/DC/AC converter

In this paper a systematic fuzzy sliding mode controller is presented for permanent magnet synchronous motor (PMSM) sensorless drives. The fuzzy sliding mode controller is designed based on input–output feedback linearization control technique. The extended Kalman filter is used to estimate the speed, position and load torque. The PMSM is fed from indirect power electronics converter. This indirect converter is controlled by the sliding mode technique. This control technique allows the minimization of harmonics introduced by the line converter, including the control of power factor and DC-link voltage. The robustness of the overall system is studied using simulation for different operating modes and varied parameters.

Application of AC/DC/AC converter for sensorless nonlinear control of permanent magnet synchronous motor.

In this paper, a nonlinear controller is presented for permanent magnet synchronous motor (PMSM) sensorless drives. The nonlinear controller is designed based on input-output feedback linearization control technique. The extended Kalman filter is used to estimate the speed, position and load torque. The PMSM is fed from indirect power electronics converter. This indirect converter is controlled by the sliding mode technique. This control technique allows the minimization of harmonics introduced by the line converter, including the control of power factor and DC-link voltage. We study the robustness of the overall system using simulation for different operating modes and parameters variation.

Sensorless control strategy for permanent magnet synchronous motor fed by AC/DC/AC converter

In this paper, a non-linear controller is presented for permanent magnet synchronous motor (PMSM) sensorless drives. The non-linear controller is designed based on an input-output feedback linearization control technique. The extended Kalman filter is used to estimate the speed, position and load torque. The PMSM is fed by an indirect power electronics converter. This indirect converter is controlled by a sliding mode technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. We study the robustness of the overall system using simulation for different operating modes and varied parameters.

Modeling synchronous reluctance motors including saturation, iron losses and mechanical losses

The correct modeling and control of synchronous reluctance motors (SynRMs) requires a very good parameter identification. Accordingly, a simple experimental off-line approach for the calculation of the viscous friction coefficient, constant friction load, iron loss resistance and direct/quadrature inductances is presented in this paper. The iron loss resistance and the direct/quadrature inductances were introduced in the model as lookup tables. The motor behavior under vector control is analyzed considering both saturation and iron losses. Simulation results of a vector-controlled 2.2 kW SynRM are compared with experimental tests in order to show the effectiveness and accuracy of the proposed parameter identification methods.

Systematic fuzzy sliding mode approach combined with extented Kalman filter for permanent magnet synchronous motor control

This paper proposes a new state observer based on an extended Kalman filter (EKF) for the sensorless systematic fuzzy sliding mode control of permanent magnet synchronous motors (PMSM). The observer can obtain a precise estimation of rotor speed and position. Load torque is also observed and used as the feed-forward compensation to improve the system performance during load torque changes. In this system, the initial rotor position is not necessary for the start up.

The use of the modified Prony's method for rotor speed estimation in squirrel cage induction motors

It is well known that rotor speed estimation assumes a paramount importance for the correct diagnosis of bearings, air-gap eccentricities, or rotor bar defects. In this paper, a new technique for rotor speed estimation using a modified Pronys method is proposed. The algorithm developed for this purpose is based on tracking the frequencies of the rotor slot harmonics (RSH) that exist in stator currents of most squirrel-cage induction motors. High-order RSH frequencies are used to avoid the possible effect of harmonics stemming from other sources. The proposed modified Pronys method shows a great ability for tracking RSH frequencies and then the rotation speed. In addition, this technique can deal with noisy and nonstationary signals and it requires only few data samples, which reduce considerably the computational time and data storage requirements. Consequently, the proposed algorithm is suitable for online implementation. The methods effectiveness is verified by simulation and experimental tests.

Adaptive nonlinear control combined with unscented Kalman filter for permanent magnet synchronous motor fed by AC/DC/AC converter

In this paper, a adaptive non-linear controller is presented for permanent magnet synchronous motor (PMSM) sensorless drives. The adaptive non-linear controller is designed based on an input-output feedback linearization control technique. The unscented Kalman filter is used to estimate the speed, position and load torque. The PMSM is fed by an indirect power electronics converter. This indirect converter is controlled by a sliding mode technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. We study the robustness of the overall system using simulation for different operating modes and varied parameters.