Ibrahim El-Arabawy

Fault Signature Production for Rolling Element Bearings in Induction Motor

This paper investigates the faults of ball bearings and their effect on both machine vibration and stator current. Bearing faults are categorized into two main groups according to the fault signature produced and appear in machine vibration and stator current. They are single-point defect and generalized roughness. Single-point defect produces one of the four predictable characteristic fault frequencies depending on which surface of the bearing contains the fault (inner race, outer race, balls, cage). While, generalized roughness produce broadband change in machine vibration and stator current. Experimental results are given for healthy bearing and when it becomes faulty to detect the effect of single-point defect and generalized roughness faults on it and on machine vibration and stator current.

Non-linear sliding-mode control of three-phase buck-boost inverter

The development of static power converters capable of transforming DC energy obtained from alternative sources into AC has become one of the main challenges in renewable energy systems. In this context, the buck-boost inverter is advantageous for being capable of providing an AC output voltage higher or lower than the input DC voltage in a single power conversion stage. In this paper, a controller based on the non-linear sliding mode theory is proposed for a three-phase buck-boost inverter to track a desired AC reference voltage. Unlike conventional linear sliding mode controllers that depend on the errors of the state variables, the control law used here depends only on the input and output voltages of the converter without the need to the inductor current measurement, which reduces the system complexity and cost. The proposed controller can not only track the desired reference quickly and accurately, but also achieve a high immunity to external perturbations, such as input voltage and output load disturbances. Several simulation studies are presented in order to investigate the performance of the proposed controller.

Inverter Faults In Variable Voltage Variable Frequency Induction Motor Drive

A simulation and practical results of a common fault occurred in the voltage source inverter used for v/f drive for induction motor, namely; open circuit fault and short circuit fault, are introduced. Results and analysis lead to extract rules for different fault conditions. These rules help for both fault detection and localization.

Practical methodology of control and protection of field oriented induction machine using digital signal processing

This paper introduces a review for field oriented control (FOC) induction machine. The practical field oriented control and fault detection of induction machine using Digital signal Processor (DSP) card. Including the design of the measuring circuit which is needed in both control and fault detection of induction machine. Due to the DSP card deal with low electric signal an isolation card between the measuring circuits and the DSP card will be design. A new power module three phase inverter circuit will use and the design of its protection circuit. The Simulink block diagram of the induction machine with DSP will be introduced. Under the DSP control card some results of the induction motor will be shown.

Rectifier Faults In Variable Voltage Variable Frequency Induction Motor Drives

This paper investigates the uncontrolled rectifier faults in variable voltage variable frequency induction motor drive. These faults are categorized to either open circuit or short circuit for one diode or more. The fault results are compared with the results of a healthy drive system depending on measuring the dc-link voltage and recording the root mean square value of the input voltage to the motor terminals. An algorithm which represents the fault cases gives a way for fault detection technique is introduced. The system under both healthy case and faulty cases is simulated and validated experimentally.

Performance of a five-phase induction machine with single-tooth winding under open-phase conditions

Five-phase induction machine with a single-tooth winding is shown promise when compared with a conventional five-phase distributed winding in some applications such as high frequency induction motors and motors with long stators and limited diameters. Unlike a conventional five-phase with distributed winding, the effect of non-fundamental subspaces is a quite different in a single-tooth winding. In this paper, a five-phase induction machine with a single-tooth winding is investigated under open-phase conditions. Firstly, the MMF distribution of a conventional full-pitch concentrated winding and a single-tooth winding are compared to explore the effect of different subspaces. Then, the steady-state model using the symmetrical components theory is derived to compare the machine performance under healthy and open-phase conditions. A prototype five-phase machine with a single-tooth winding has been used to verify the derived mathematical model under different operational cases.

A Modified Selective Harmonic Elimination method for balancing capacitor voltage in modular multilevel converter

The modular multilevel converter (MMC) has proven itself as an exceptionally effective converter in High Voltage DC (HVDC) applications, due to its modularity, reliability and robustness. Yet, it requires unique modulation techniques to accomplish the troublesome capacitor voltage balancing. In this paper, a Modified Selective Harmonic Elimination (M-SHE) is introduced where the switching of the submodules is done in a certain preconfigured arrangement which accomplishes the required capacitor balancing. The proposed modulation technique is then compared with Third Harmonic Injection — Phase Shift — Sinusoidal Pulse Width Modulation (THI-PS-SPWM) and with the Classical Selective Harmonic Elimination (SHE). Performance of the proposed M-SHE, classical SHE and THI-PS-SPWM for a five-level MMC unit is evaluated based on time-domain simulation studies in the MATLAB/SIMULINK software. The reported study results demonstrate that the M-SHE satisfies capacitor balancing and has lower Total Harmonic Distortion (THD) than the classical SHE and THI-PS-SPWM.

Performance of nine-switch inverter-fed asymmetrical six-phase induction machine under machine and converter faults

This paper investigates the performance of an asymmetrical six-phase induction machine fed by a six-phase nine-switch voltage source inverter under both healthy and open motor phase cases. In the literature, the nine-switch inverter topology is proposed as a suitable reduced switch-count converter topology for six-phase drives, where each pair of phases share the same converter leg. First, a brief summary about this topology along with its limitations are introduced. The six-phase drive system topology is then investigated under both inverter and machine open-circuit faults. Conventional rotor field oriented controller is employed as a controller platform for such a drive. Optimal current control is used under open phase conditions to ensure a certain optimization criterion, namely, minimum stator copper loss or maximum torque production. The system is investigated through a simulation study using MATLAB/SIMULINK.

A particle swarm optimization for optimum design of fractional order PID Controller in Active Magnetic Bearing systems

Active Magnetic Bearings (AMBs) are now widely used for high rotational speed applications; where friction and maintenance cost are to be minimized; such as turbo-machinery and high speed compressors. Conventional PID controllers are commonly employed in these systems. The high speed variations cause gyroscopic effects which degrade the system performance. Moreover, under high speeds, AMB systems may experience instability. In this paper, the design of an active magnetic bearing system based on fractional order PID (FOPID) controllers is introduced. The controller gains are optimized using particle swarm optimization (PSO) approach. A typical AMB system with four degrees of freedoms (DOFs) is used to assess the proposed controller against conventional PID controllers. Different system constraints including the current limits of the power amplifiers are considered in the optimization problem.

Simulation aides in comparison between different methodology of field oriented control of induction motor based on flux and speed estimation

The most popular induction motor drive control method has been the field oriented control (FOC) in the past two decades. Furthermore, the recent trend in FOC is towards the use of sensorless techniques that avoid the use of speed sensor and flux sensor. The sensors in the hardware of the drive are replaced with state observers to minimize the cost and increase the reliability. This paper is mainly focused on the state observers to estimate the states that are used in the FOC algorithms frequently. The closed loop and extended Kalman filter (EKF) techniques are applied for the FOC of induction motor. Finally, both techniques are simulated based on Mathlab® Simulink program.