Rashid Alammari

Common-Mode Voltage and Vibration Mitigation of a Five-Phase Three-Level NPC Inverter-Fed Induction Motor Drive System

Common-mode (CM) voltage is one of the main reasons for the flow of bearing currents in induction motors (IM) that ultimately leads to the bearing failure and causes severe vibrations. For three-phase IM drives, many works have been reported either on the reduction or on the elimination of CM voltages that are generated due to pulse width modulation (PWM) action of the feeding power converters. However, for five-phase IM drives, very few studies are available with the perspective of the CM voltage elimination. Also, the effect of CM voltage on the mechanical vibrations of a five-phase IM has not been reported in the literature. Hence, in this paper, firstly, the modeling of CM current generated in the five-phase IM is done and its expression based on admittance transfer function is derived. Then the CM voltage is eliminated from a five-phase three-level neutral point clamped (NPC) voltage source inverter. The space vector pulse width modulation (SVPWM) technique is developed for the elimination of CM voltages. Only those switching states are selected which give zero CM voltage. The same selected switching states also give the balanced dc link capacitor voltages. Its effect is observed on the mechanical vibration of the motor and it is correlated with the CM current. The mechanical vibration is observed for both, with and without CM voltage elimination. Both the simulation and experimental results are given to validate the concept proposed.

Sensorless sliding mode observer for a five-phase permanent magnet synchronous motor drive.

This paper deals with the sensorless vector controlled five-phase permanent magnet synchronous motor (PMSM) drive based on a sliding mode observer (SMO). The observer is designed considering the back electromotive force (EMF) of five-phase permanent magnet synchronous motor. The SMO structure and design are illustrated. Stability of the proposed observer is demonstrated using Lyapunov stability criteria. The proposed strategy is asymptotically stable in the context of Lyapunov theory. Simulated results on a five-phase PMSM drive are displayed to validate the feasibility and the effectiveness of the proposed control strategy.

PWM scheme for dual matrix converters based five-phase open-end winding drive

The paper present simple carrier-based pulse width modulation scheme for three to five-phase matrix converters feeding a five-phase machine from both ends. The two matrix converters feeding a five-phase induction machine are supplied from a common single three-phase source. The five-phase outputs of the two matrix converters are assumed to supply a five-phase machine from both ends. The paper presents the analytical approach to obtain the expression of modulating signals that are used to generate the switching pulses for the matrix converter. Simulation results are presented to support the idea of the proposed modulation scheme.

Common-mode voltage control through vector selection in three-to-five phase matrix converter

Multi-phase matrix converters (more than three phase) are distinctively advantageous as because of reduced per-phase current and unity power factor operation. The electrical motors supplied through these converters do have the common-mode voltage problem. In this paper, an approach to reduce the common-mode voltage is presented through appropriate vectors selection. An availability of the (35) 243 states gives selection freedom within the constraints. The useful ninety three vectors with ninety active and three zero vectors are implemented in conventional space vector modulation technique in matrix converter. The space vector control technique is used with selective large and medium vectors with their disposition in d-q plane having controlled mapping in x-y harmonics plane to reduce the common-mode voltage is discussed. Two operating modes, one within the linear range and another with non-linear range (ten stepping mode) is presented with their performance. The common mode voltage (CMV) voltage reduction with rms voltage gain is observed in ten step operation. The effectiveness of these control algorithms are presented through simulation and verified by implementing it on 2 kVA matrix converter.

Space vector pulse width modulation scheme for three to seven phase direct matrix converter

In this paper a generalized multi-phase space vector theory is considered for developing the space vector modulation of a three-phase to seven-phase direct matrix converter (DMC). The modulation is based on the control of the voltage vectors in the first d-q plane, while imposing the remaining voltage vectors in the second and the third planes (x1-y1, x2-y2) zero. The duty cycles of the bidirectional switches are obtained using space vector modulation theory. The output to input voltage transfer ratio is obtained as 0.7694 for unity input power factor operation. The proposed matrix converter system offers full control of the input power factor, no limitation on the output frequency range and nearly sinusoidal output voltage. The proposed space vector algorithm can be fully implemented on a digital platform. The theoretical analysis is confirmed by digital simulations which is further verified using experimental implementation.

Finite set model predictive current control with reduced and constant common mode voltage for a five-phase voltage source inverter

Multiphase drives are now becoming serious competitor to traditional three-phase drives due to reasons of better fault tolerant property and reduced per-phase converter rating that are especially suited to high power drives application. One of the major factor of widespread research on multiphase drive are the availability of high computational power of control platforms such as DSP and FPGAs. With availability of such computationally powerful tool of DSP/FPGA leads to the adoption of model predictive control (MPC) in electric drive. This paper present current control of a five-phase inverter using MPC with the aim of achieving constant common mode voltage. By achieving constant common mode voltage (CMV), bearing current can be greatly reduced. This is achieved by proper selection of space vectors and analysis of drop in voltage gain is presented. Simulation results are supported by experimental approach.

Impact on power quality due to large-scale adoption of compact fluorescent lamps – a review

ABSTRACT The demand of electrical energy has grown tremendously in the last couple of decades across the globe. The energy conservation and management has attracted the attention of stake holders for efficient utilisation of the resources. One of the major steps taken by the authorities towards conservation of electrical energy is replacement of incandescent lamps (ILs) by compact fluorescent lamps (CFLs). CFL uses electronic circuit for its ignition, making them a non-linear load on utility grid. Large-scale replacement of ILs has enormous effects on utility grid in terms of power quality. This paper reviews the work conducted by several researchers investigating the effect of using CFLs on power quality. Basic terminologies related to power quality is defined. The experimental results elaborate the pollution on the grid in the term of total harmonic distortion in current due to adoption of CFLs. The methodologies of harmonic measurement system are reviewed. Different software used for the analysis is presented. The paper will help the researchers to receive a comprehensive overview of power-quality issues.

Modelling and implementation of SVPWM technique for a fifteen-phase voltage source inverter for sinusoidal output waveform

In this paper space vector model of a fifteen-phase voltage source inverter (VSI) is presented. The space vector Pulse Width Modulation (SVPWM) of a fifteen-phase voltage source inverter (VSI) with the aim of producing sinusoidal output waveform, is illustrated. Generalized space vector theory is used to model the inverter and the SVPWM. As per the general inverter switching theory there are 215 = 32768 switching states are possible that yield 32766 active space voltage vectors and two zero voltage vectors at the origin. Out of the total 32766 active voltage vectors, 210 voltage vectors are utilized for the implementation of SVPWM. The sinusoidal voltage is obtained by controlling the duty cycle the voltage space vectors of d-q plane when voltage space vectors of other six x-y planes are set to zero. Maximum modulation index is used to get balanced sinusoidal output. The theoretical results are verified by simulation and experimental results with R-L load.

High performance backstepping control of a fivephase induction motor drive

Multiphase electric drives have been investigated and proposed for applications where the highest overall system reliability and the reduction in the total power per phase are required. This paper deals with the high performance Backstepping control strategy which is based on laws allowing an explicit control of system stability in closed-loop operation of five-phase induction motor drives. This control focuses on the transient analysis in nonlinear adaptive control which allows tending asymptotically the process to a reference model. The reference model is established from the desired performances of the drive system in the closed-loop mode of operation system. This paper presents the Backstepping control technique (BC) and compared with the indirect rotor flux oriented control of a five phase IM drives. Simulation results are provided to support the findings and validate the control scheme.

Ethics in engineering education: A literature review

Engineering Ethics is an important topic to be developed in engineering education curriculum. Despite its importance, ethics is not much investigated in engineering education as compared to other disciplines, in particular medicine or biology education. In this paper, a comprehensive review of engineering ethics is provided. The review covers three main topics: 1) Attributes of ethical engineers, 2) Content, logistics and pedagogy of engineering ethics, and 3) Assessment of engineering ethics. A particular focus is given to the Defining Issues Test (DIT) and the Engineering and Science Issues Test (ESIT) that is considered a promising instrument to assess moral judgment development of science and engineering students. Final remarks will conclude the paper.