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Electrical machine efficiency improvement has been paid more attention over the past years. Using Permanent Magnets (PMs) in various modern electrical machines is one of the most favorable approaches to increase machine efficiency. However, PMs still have a significant disadvantage that is the demagnetization issue. Therefore, these demagnetized PMs need to magnetize for regaining their initial capability considering the demagnetization level. Therefore, first of all, this paper proposes the demagnetization behavior of NdFeB PMs due to thermal effect. Then, these PMs are magnetized using a proposed simple magnetizing technique considering various demagnetization conditions. Finally, the results indicate that the most complete demagnetized PMs are able to significantly recover to their initial capability.

Among various types of electric motor, selecting an induction motor for electric vehicle (EV) is still being discussed. Efficiency and weight of induction motor are two significant disadvantages compared to other motors. To solve these two concerns, this paper proposes a study to effectively improve induction motor efficiency and its power density. The stator winding of proposed three phase induction motor is rewound by decreasing number of turn and by increasing stator coil size. This proposed motor is suitable for EV driven by inverter in high speed operation which the rated power of this motor is approximately two times more than that of its original. As the results, the motor efficiency is improved since its total loss is slightly increased. In addition, as an increasing twice of rated motor power approximately with the same motor weight, the power density of the proposed motor is also enhanced. Three sizes of three-phase inductor motor including 0.75, 2.25, and 3.7 kW are tested to illustrate the proposed approach in this study.

In order to use a generator-set for charging battery of the stand-alone hybrid renewable power generation system in remote area efficiently, the generator-set needs to be operated in various speeds considering battery voltage. The conventional field excited synchronous generator, which is used to convert mechanical power to electrical power from internal combustion engine (ICE), cannot handle this important function. Therefore, this paper presents an effective technique to improve the efficiency of the generator-set using interior permanent magnet synchronous generator (IPMSG). Two designed IPMSGs including 6 cm and 8 cm stator core lengths, which are be able to operate in the maximum efficiency speed region of the ICE, are proposed for selecting the appropriate generator in this study. Finally, the testing results show that the proposed 8 cm stator core length IPMSG with suitable operation can be effectively and efficiently used as the generator-set for charging the 48 V battery systems.

An electrical energy monitoring system helps improve the security and reliability of a hospital operating system which can also indirectly enhance energy efficiency itself. However, a large hospital has a complex electrical system which leads to the big data issue from the installed monitoring system in this size-scaled hospital. Therefore, this paper proposes K-mean clustering technique, which is one of the effective data mining techniques, to analyze the big data from the electrical energy monitoring system in hospital. The case study is a large hospital with 200 in-patient beds in Thailand. Without loss of generality, electrical load profile is used for analyzing instead of using the electrical energy. Finally, the proposed data clustering technique is able to characterize electrical load profiles effectively for each hospital floor. This technique also identify the abnormality of these characterized electrical load profiles in various scenarios which hospital system operators can use them to consider the security, reliability, and energy efficiency of their operating systems.

Microemulsiflcation is one of the novel techniques to reduce viscosity of vegetable oils to avoid durability problems in diesel engines. Microemulsion biofuels are transparent, thermodynamically stable, and single-phase mixtures of vegetable oils and ethanol in the presence of surfactants and co-surfactants. Additives have also been included in microemulsion biofuel formulations to improve their stability and fuel properties; however, there is limited research on the effect of additives on emission characteristics of microemulsion biofuels. In this study, microemulsion biofuels were formulated from palm oil/diesel blend (1:1 v/v), ethanol, surfactant, and co-surfactants. Five additives, ethylene glycol butyl ether (EGBE), diethylene glycol ethyl ether (DEGEE), propylene glycol ethyl ether (PGEE), dipropylene glycol methyl ether (DPGME), and ethyl acetate (EA), were used to study the effect of additives on phase behaviors, fuel properties, and emission characteristics. The results showed that studied additives could improve some fuel properties of microemulsion biofuels with negligible effect on phase stability. Additionally, it was found that carbon monoxide (CO) emissions from microemulsion biofuels with DEGEE and EA, and nitrogen oxide (NOx) emissions from microemulsion biofuels with all additives were lower than those from diesel and biodiesel. Therefore, DEGEE and EA can be considered as promising additives for microemulsion biofuel formulations, which can improve fuel properties as well as can significantly reduce CO and NO x emissions below the levels of diesel and biodiesel. These encouraging results offer options of additives for biofuel applications.

In order to enhance energy security while reducing environmental impact, the government of Thailand has established policy to develop domestic energy resources to increase energy stability and to sufficiently meet the future demand. Aiming to achieve a 20% share of renewable energy by 2022 according to the 15-Year Renewable Energy Development Plan (REDP), it is necessary to work out a plan to explore new renewable energy resources and technologies, encourage more investments from both public and private sectors, and promote entrepreneurships to transfer laboratory work to commercial production in manufacturing scale. In this paper, first the situation of Thailand's energy is presented. The energy plan in next 15 years will also be mentioned. Next, the potential of renewable energy resources are also discussed. Finally, the study of the technology roadmap of the renewable energy industry in Thailand is proposed to emphasize the importance of the present and upcoming technology and product trend.

This paper presents a phase to ground leakage current in 3-phase induction motor caused by switching voltage source. The phase to ground leakage current of induction motor is effected by impedance of motor insulator which varied with switching frequency from voltage source. So various testing voltage sources included variable frequency square wave, variable frequency sine wave and dc source are supplied to induction motor in order to find out the impedance of motor insulator. Finally, test results of 1hp, 3hp and 5hp induction motors are shown and carried out to evaluate the phase to ground insulation motor impedance model.

This paper presents a preliminary study of the technique of brushless synchronous reluctance generator (BSRG) combined with the utility power supply for generating a nonsinusoidal three-phase voltage waveform. The PWM techniques have still faced a few problems of how to control the amplitude and the k/sup th/ order harmonic voltage wave. The harmonic generator using BSRG technique can be used as source and sink power characteristics in any kind of load in the power system. Therefore, the frequency and amplitude of the wave form obtained from this harmonic generator can be independently controlled in order to use for a study of how the harmonics affect three-phase induction motors or transformers. Finally, the nonsinusoidal voltage waveforms of the fundamental with the 3/sup rd/, 5/sup th/, 7/sub th/ and 10/sup th/ order harmonics at various voltage distortion factors (VDF) obtained from the BSRG technique are illustrated and discussed.

This paper presents the technique of how to minimize power from the supply when a three-phase induction motor is under the load test. The load test enables the determination of the value of load power, current and power factor of the induction motor. In practice, a DC generator or eddy current brake is applied for the mechanical test. The objective of this paper is to propose a load test method using two pulleys for changing speed of an induction motor. The second induction machine is controlled to operate as an induction generator in order to transfer the energy to the supply, therefore the power required during the test is obviously reduced. The study of how to control the induction motor operated as generator will be the useful information for developing the induction generator system (IG) to work with variable speed and load, and to make it work as a stand alone generator.