José Salvado

Design of a system for analysis and monitoring of vibrations in Linear Switched Reluctance machines

The acceptance and usage of switched reluctance machines has been conditioned, beside other reasons, by the acoustic noise produced. Research efforts to minimize vibrations on the design stage and during machine operation mainly concentrate on rotational machines and only a few works can be found focusing on the linear configuration. This paper proposes a system to analyze and monitoring vibrations in switched reluctance machines, with special focus on the linear configuration, aiming a real-time data operation. The system is based on the MSP430 family of microcontrollers manufactured by Texas Instruments Inc, and comprises a network of intelligent accelerometers sensors, distributed along the machine mechanical structure. The intelligent sensors communicate via USB 2.0 protocol with the Host PC. An experimental vibration tests applied to a Linear Switched Reluctance Actuator (LSRA) is performed and results are presented to validate the proposed system.

Vibration analysis of a linear switched reluctance actuator

The main drawback of switched reluctance machines acceptance is the acoustic noise produced. Research efforts to minimize vibrations in this type of electric machines concentrate mainly on the rotational configuration and only a few works can be found focusing on linear actuators. This paper presents the results of finite elements analysis of vibration frequencies for a linear switched reluctance actuator. The results obtained serve as reference and support for experimental modal analysis and characterization of vibrations and acoustic noise in this type of machines.

Motivating younger students by using engineering graduation projects to facilitate their work

This paper addresses a way to motivate freshmen students benefiting from the work of term students in graduation projects. The application of concepts from digital electronics and analog telecommunications systems can reinforce cooperation of students at different levels on a positive way and strength skills. This can also be used as demonstrative experiences to attract prospective students to electrical engineering courses. The experience of a cooperative work with graduation projects is presented and how it can facilitate younger students work and thus contribute for their motivation and skills. The graduation projects used are briefly presented and some results are shown and discussed.

Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance Actuator

This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM) to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design.

A Simple yet Effective Semi-Anechoic Chamber for the Acoustic Characterization of an LSRA

This paper presents a simple and cost effective solution of a semi-anechoic chamber suitable for the acoustic noise characterization of a Linear Switched Reluctance Actuator (LSRA). Using simple construction and assembling techniques, and low-cost materials, it allows significant acoustic isolation characteristics from the environmental noise, caused by peoples activities, other machinery operation, etc. The average attenuation achieved is better than 30 dB for a noise source place at 1 meter distance from its walls. The overall test results demonstrate an affordable yet effective semi-anechoic chamber solution, and prove its adequacy for the specific purpose of characterizing a LSRA in terms of the acoustic noise produced.

Improved distributed system for analysis of vibrations in linear switched reluctance actuators

Research efforts have been taken to characterize the vibrations in switched reluctance machines but only a few works focus on the linear configuration. This paper proposes a realtime data acquisition system to monitor and analyze the vibrations in this type of machines with special focus on the linear switched reluctance actuator. The system is based on the Texas Instruments MSP430F54xx family of microcontrollers and comprises a modular network of accelerometer sensors, distributed along the mechanical structure of the machine. The sensors modules communicate with the Host PC via USB 2.0 protocol and data is collected and processed in MATLAB®.