Mario J. Duran

Addressing Learner Satisfaction Outcomes in Electronic Instrumentation and Measurement Laboratory Course Organization

This paper proposes and details a course organization methodology based on learner satisfaction achievement. The approach follows the prevailing tendency in modern university reforms which are primarily concerned about how people learn. As a consequence, the learner has been placed as the main actor of the teaching-learning process. Nevertheless, the current learning literature has not addressed the measurement of learner satisfaction within laboratory and practical subjects. This study develops a general and comprehensive methodology for learner satisfaction measurement in practical subjects. As a case example, the proposed methodology has been applied to an electronic instrumentation and measurement course, confirming the variables with a significant influence on learner satisfaction and becoming the starting point for curriculum redesign based on the learner satisfaction approach. To assess the improvement of the proposed course organization methodology, a comparison with previous academic years has been performed showing the students rated score evolution. Results fully confirm the validity of the technique and the novel course organization

Independent vector control of asymmetrical nine-phase machines by means of series connection

The interest in multi-phase machines for high performance applications has been growing in recent years due to their potential advantages over three-phase machines. One of the possibilities of taking advantage of the additional degrees of freedom that exist in multi-phase machines is the series connection of several multi-phase machines, with the supply coming from a single multi-phase inverter. Among the different choices, the quasi nine-phase machine with three sets of three-phase windings spatially displaced by 20 degrees, is particularly attractive for high-power applications. This paper discusses the possibility of connecting a number of such asymmetrical nine-phase machines and explains how independent control can be achieved although a single nine-phase inverter is used as the supply. Mathematical derivations and simulation proof of independent vector control, achievable with this system, are provided for the series connection of three nine-phase machines and a three-phase machine. The existence of the independent control of the machines is fully verified both in torque and speed mode using indirect rotor-flux oriented control principles

Fault-tolerant current predictive control of five-phase induction motor drives with an open phase

Multiphase induction motor drives have recently gained attention in traction applications where high overall system reliability and a reduction in the total power per phase are required. The additional phases compared to standard three-phase drives allow the creation of a rotating flux even in fault conditions, guaranteeing that the system continues operating without torque ripple, vibrations and noise. The control technique in post-fault situation must ensure ripple-free operation of the machine reducing the achievable torque to maintain the stator currents within rated values. This paper details the modifications in a predictive control scheme to allow post-fault operation of the five-phase drive when one phase is open. Simulation results are provided to confirm the ability of the modified control scheme to operate in fault-tolerant mode with limited currents, maximum torque and low torque ripples.

Modeling Learner Satisfaction in an Electronic Instrumentation and Measurement Course Using Structural Equation Models

The prevailing tendency in modern university reforms is towards ldquohow people learn,rdquo following a learner-centered approach in which the learner is the main actor of the teaching-learning process. As a consequence, one of the key indicators of the teaching-learning process is the measurement of learner satisfaction within the classroom. Learner satisfaction has traditionally been measured using survey responses to a standard learning survey. However, more scientific analysis should be performed to assess adequately not only learner satisfaction but also the main dimensions that have a positive impact on learner satisfaction. The purpose of this paper is to define a structural and measurement model in which causal relationships among these different dimensions are adequately established. The methodology is based on a multivariate regression model (Structural Equation Models) to establish scientifically a structural model for learner satisfaction within a classroom, measuring its validity and reliability. The proposed approach has been applied to model learner satisfaction in an electronic instrumentation course at the University of Seville, Spain. The results and implications of this study will contribute to improve student satisfaction with respect to the dimensions considered.

eDSPlab: A remote-accessed instrumentation laboratory for digital signal processors training based on the Internet

This paper presents a new model for using real instrumentation laboratories for digital signal processors (DSP) training on the Internet employing a virtual environment based on Labview. Remote instrumentation interest has been growing immensely as a result of the telecommunication network development and middleware technologies, specially remote signal processing instrumentation/systems used in both industrial and educational approaches. In engineering education, a key activity to be improved is the learning process in digital signal processing instrumentation. Industrial development also demands network distributed and remote applications for on-line control and off-presence monitoring. A remote-accessed instrumentation laboratory is proposed in this approach versus simulation and software-based tools. The virtual on-line laboratory has been developed and validated in the field of electronic digital measurement processing and the effectiveness of the approach is experimentally verified locally and remotely. The prototype has been successfully implemented during the last course 2004/2005 at the Electronic Engineering Department of the University of Seville, Spain

Multi-Dimensional Space Vector Pulse Width Modulation Scheme for Five-Phase Series-Connected Two-Motor Drives

A space vector PWM (SVPWM) technique for multiphase voltage source inverters (VSI), based on a multidimensional space approach, is considered in this paper. The additional degrees of freedom, which appear as the number of phases increases, make the SVPWM more complex because VSI space vectors are not in a single two-dimensional space any more. Existing approaches are predominantly based on n- dimensional space decomposition into (n-l)/2 two-dimensional sub-spaces and this is adequate when the output is required to be sinusoidal or sinusoidal with higher harmonic injection. However, in the case considered here (five-phase series- connected two-motor drive) there are two independent reference voltage vectors in the two sub-spaces and the problem of active voltage vector selection arises. The methodology outlined here is capable of overcoming this problem, since the voltage space vectors are selected on the basis of criteria that are formulated for the multi-dimensional space, so that all the two-dimensional sub-spaces are simultaneously considered. The paper at first summarises the mathematical analysis that establishes the necessary conditions for appropriate selection of the voltage space vectors in the multi-dimensional case. Different criteria for the general n-phase case are presented for the selection of the VSI space vectors and the validity of the SVPWM scheme is verified by simulation of a five-phase VSI supplying two series-connected five-phase motors.

Multi-dimensional space vector pulse width modulation for disturbance-free operation of a five-phase AC motor drive

One of the advantages of multi-phase machine variable-speed drives is the possibility of disturbance-free mode of operation when one or more phases are lost during normal operation. This requires the modification of the control algorithm in post-fault operation. This paper investigates the use of multidimensional space vector PWM technique to synthesise required voltages for the disturbance-free mode of operation of a five-phase machine in post-fault operation. Different cases, with regard to the number and spatial position of faulted phases, are covered, showing the necessary conditions mathematically and enabling examination of the performance of the modulation technique. Simulation results confirm the adequacy of the multi-dimensional PWM approach to control the supply of the machine in the post-fault mode of operation.

Modeling of a five-phase induction motor drive with a faulty phase

Fault-tolerance capability is one of the most attractive characteristics of multiphase machines for industrial applications. Resent research has proven that post-fault ripple-free operation is possible as long as the reference currents generate a smoothly rotating magnetomotive force (MMF). However, the power converter and multiphase machine behaviour and interaction during different types of faults has been hardly studied, modelled and verified. This work analyses the behaviour of a real five-phase induction machine when a fault appear in one phase of the power converter. Two cases are considered, an open-phase fault condition where a power leg of the converter is disconnected, and an open-phase fault condition where the free-wheel diodes continue working. Two models are also presented based on PSIM and SIMULINK for the analytical study of the system under the fault conditions, and verified comparing the obtained results with the real case.

Real-Time Implementation of Multi-Dimensional Five-Phase Space Vector PWM Using Look-Up Table Techniques

Space vector PWM (SVPWM) has been recently developed for multi-phase motor drives on the basis of the multidimensional space approach. Although showing excellent characteristics with regard to performance, the multi-dimensional based SVPWM is very difficult for real-time implementation due to the excessive computational demands of the algorithm. A further difficulty stems from the dependence of the computation time on the operating conditions. This paper attempts to alleviate these problems encountered in the real-time implementation of multi-dimensional SVPWM algorithms, by using look-up tables that include off-line information. The performance of the approximate algorithm based on the off-line calculations is evaluated by simulation for different requirements regarding the output voltage synthesis. The algorithm is finally implemented in a TMS320C6711 Texas Instruments DSP, thus proving the feasibility of real time implementation with fixed computational time, at the expense of the additional memory for the look-up table storage.

Analysis of the Power Quality in Six-phase Induction Motor Drives with Arbitrary Winding Spatial Shifting

Multiphase machines are becoming an alternative to the three-phase standard in high power applications with high reliability requirements. Due to the capability to inherit off-the-shelf three-phase technology, the most popular choice at industry is the use of multiple threephase windings. The disposition of the different sets of threephase winding is however varied. In the specific case of sixphase machine, a spatial shifting among the three-phase windings of 0o, 30o and 60o has been used in dual-three-phase, asymmetrical and symmetrical machines, respectively. This spatial displacement has an impact on the power quality of the currents that supply the machine since the same magnetomotive force (MMF) in the airgap can be generated with different harmonic cancellation between phases. This work considers an arbitrary spatial shifting of the threephase windings in order to explore its impact on the power quality from the machine-side. Extensive simulation results compared the different types of six-phase machine and some conclusions are extracted about the advantages of each choice.