IPMSM torque control strategies based on LUTs and VCT feedback for robust control under machine parameter variations

In recent years, Interior Permanent Magnet Synchronous Machines (IPMSMs) have attracted a considerable attention in the scientific community and industry for Electric and Hybrid Electric Vehicle (HEV) propulsion systems. Lookup Table (LUT) based Field Oriented Control (FOC) strategies are widely used for IPMSM torque control. However, LUTs strongly depend on machine parameters. Deviations of these parameters due to machine ageing, temperature or manufacturing inaccuracies can lead to control instabilities in the field weakening region. In this paper, two novel hybrid IPMSM control strategies combining the usage of LUTs and Voltage Constraint Tracking (VCT) feedbacks are proposed in order to overcome the aforementioned controllability issues. Simulation results that demonstrate the validity of the proposed approaches are presented.Postprint (author's final draft

A globally exponentially stable position observer for interior permanent magnet synchronous motors

The design of a position observer for the interior permanent magnet synchronous motor is a challenging problem that, in spite of many research efforts, remained open for a long time. In this paper we present the first globally exponentially convergent solution to it, assuming that the saliency is not too large. As expected in all observer tasks, a persistency of excitation condition is imposed. Conditions on the operation of the motor, under which it is verified, are given. In particular, it is shown that at rotor standstill---when the system is not observable---it is possible to inject a probing signal to enforce the persistent excitation condition. {The high performance of the proposed observer, in standstill and high speed regions, is verified by extensive series of test-runs on an experimental setup

A study of energy efficiency opportunities in Putrajaya Maritime Centre towards green building

Nowadays, people are more concerned about energy efficiency, energy consumption and conservations in buildings. With this in view, a project to investigate the potential of energy saving in selected building in Putrajaya Maritime Centre was carried out. The scope of the study includes identifying energy consumption in a selected building, to study energy saving opportunities, and to analyse cost investment in term of economic. As a public building and a recreation centre, these building should take the initiative to protect the environment towards green building. According to the research and analysis, several solutions are proposed to help reduce energy consumption and energy cost in the Maritime Centre. First, by improving physical properties of building components. Second, by changing the air condition temperature control setting. This paper also discuss about the improvement of lighting system efficient. From the data analysis, it has been found that huge amount of energy can be saved for a better green environment

Local weak observability conditions of sensorless AC drives

Alternating current (AC) electrical drive control without mechanical sensors is an active research topic. This paper studies the observability of both induction machine and synchronous machine sensorless drives. Observer-based sensorless techniques are known for their deteriorated performance in some operating conditions. An observability analysis of the machines helps understanding (and improving) the observer's behavior in the aforementioned conditions.Comment: arXiv admin note: text overlap with arXiv:1512.0366

High-frequency issues using rotating voltage injections intended for position self-sensing

The rotor position is required in many control schemes in electrical drives. Replacing position sensors by machine self-sensing estimators increases reliability and reduces cost. Solutions based on tracking magnetic anisotropies through the monitoring of the incremental inductance variations are efficient at low-speed and standstill operations. This inductance can be estimated by measuring the response to the injection of high-frequency signals. In general however, the selection of the optimal frequency is not addressed thoroughly. In this paper, we propose discrete-time operations based on a rotating voltage injection at frequencies up to one third of the sampling frequency used by the digital controller. The impact on the rotation-drive, the computational requirement, the robustness and the effect of the resistance on the position estimation are analyzed regarding the signal frequency

Employability skills for hospitality students in Malaysia

Malaysia needs high skilled workforce to support growth of the industry. With dynamically changing job market and progressive technological change, employees are expected to keep abreast of global economics. In the process of achieving the status of developed nation by the year 2020, Malaysia needs to restructure its workforce to ensure that middle level workers are highly skilled. Current job environment demands multi-task and skills. Thus, university graduates must be prepared to meet the demand especially in the hospitality industry. The purpose of this study is to identify the level of employability skills in the hospitality field. This research applied quantitative methodology. The respondents consist of final year students in bakery and culinary programme. Stratified sampling was used to select students in hospitality programs from 22 vocational colleges in Malaysia. Questionnaires were distributed to 841 students in five regions which are Central, South, North, East and East Malaysia (Sarawak) in Malaysia. Descriptive analysis was used to analyse the quantitative data. The results showed that the level of hospitality employability skills among vocational students in Malaysia were at high level of competence (93.2%). The research has brought meaningful implications for hospitality vocational students, employers and policy makers