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Induction motor speed measurement using motor current signature analysis technique
(2009-12-01)
Phumiphak, P.
;
Chat-uthai, C.
As the procedure of nonintrusive method for field efficiency estimation of induction motor requires the actual motor speed from direct measurement by using shaft-mounted speed encoder or optical tachometer which reduces the reliability and also increases the cost. In this paper, the sensorless speed measurement scheme using implementation of motor current signature analysis (MCSA) is proposed. Both line-fed (sinusoidal) and inverter-fed (nonsinusoidal) motors with different operating frequencies are considered. In this technique, neither equivalent circuit parameters nor structures of machine are required. Moreover for inverterfed motor, the information of inverter such as switching frequency and switching PWM scheme are not required. This proposed technique is verified from the experimental results of measured speeds of 2.2 and 4.0 kW three-phase induction motors operated under various load torques. The experimental results show that the overall speed estimation accuracy is approximately within 2 rpm errors.
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Optimal capacitances compensation for short-shunt self-excited induction generator under inductive load
(2009-12-01)
Phumiphak, P.
;
Chat-uthai, C.
This paper presents a technique for evaluating the optimal values of capacitances necessary to maintain the power quality of voltage regulation of the short-shunt self-excited induction generator (SEIG) feeding to the desired pu load under various lagging power factor conditions. The optimal values of shunt and series capacitances, and the optimal relation of ratio of air gap voltage to frequency with magnetizing reactance for the minimum voltage regulation of SEIG are evaluated by using the technique of genetic algorithm (GA) based on the equivalent circuit parameters of machine. Experimental results of 0.75 kW, short-shunt SEIG are performed to confirm the effectiveness of this proposed technique. The results are experimentally verified, which illustrate that the voltage regulations of SEIG under different inductive loads are within the limit of ± 0.06 pu.
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Performance estimation method for in-service single-phase induction motors
(2008-12-01)
Phumiphak, P.
;
Chat-uthai, C.
This paper proposes a performance estimation method for single-phase induction motors in the field at any operating load using a set of data from in-service measurement. This paper describes the use of the improved equivalent circuit models based on double-revolving-field theory which a core loss element is properly added in order to provide more accurate results. The appropriate values for the model parameters can be evaluated by the use of measured data coupled with the genetic algorithms. The estimated performance result of several motors are presented and then compared to the measured values obtained from load tests, and clearly illustrate that agreement between the proposed method and the actual one is good. © 2008 IEEE.
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Nonintrusive method for estimating field efficiency of inverter- fed induction motor using measured values
(2008-12-01)
Phumiphak, P.
;
Chat-uthai, C.
This paper presents a nonintrusive method for estimating field efficiency of inverter-fed induction motor at various operating frequencies and loads using only a set of data from field measurement. The performances of motor such as torque and efficiency can be estimated by using measurement data coupled with the use of genetic algorithm based on the modified motor equivalent circuit concept. The 2.2 and 4.0 kW motors fed by inverter were tested in laboratory under frequencies of 30, 40, 50, and 60 Hz. The subway tunnel ventilation fan motors controlled by variable speed drive were also on-site investigated. The estimated performances found to give a better correlation over a wide range of speeds and loads. © 2008 IEEE.
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Minimum cost design of small low-loss transformers
(2005-01-01)
Phophongviwat, T.
;
Chat-uthai, C.
A procedure for minimum cost design of a small low-loss low-frequency transformer is presented. The total losses of transformer can be defined to be the design constraint. The procedure for improving the accuracy of calculated total losses is the basis of the proposed total losses calculation associated with the temperature rise evaluation. The optimization technique used in this paper is based on the Genetic Algorithms. Five samples of 72 VA, 220/24 V, 50 Hz transformers have been designed and tested in order to illustrate how well the calculated total losses values using this proposed procedure matches that of the measured values obtained from the test. Finally, the simulation results of the minimum cost design with losses constraint are demonstrated. This proposed design is suitable for the design of economical transformer with total losses value options which is considerably flexible for a particular purpose.
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Sensitivity analysis for the automatic shape design of electromagnetic devices in 3D using FEM
(1997-01-01)
Ramirez, J. A.
;
Freeman, E. M.
;
Chat-uthai, C.
;
Lowther, D. A.
This work discusses a method based on the direct differentiation of the finite element matrices for the sensitivity analysis in the optimization of 3D magnetostatic problems. The formulation uses the magnetic vector potential as state variable. The results of two problems are presented. © 1997 IEEE.
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An improved constrained quasi-newton method for the solution of inverse electromagnetic problems
(1996-12-01)
Chat-uthai, C.
This paper presents the formulation of an improved direct technique called modified constrained quasiNewton method (PLBA-CR) achieved with constraint correction and objective reduction algorithms which may he used for the solution of inverse electromagnetic problems. Two problems are discussed and the results are compared with the quadratic extended penalty function (QUAP) and the augmented Lagrangian multiplier (ALM) method in terms of accuracy and calculations required. The results show that the PLBA-CR technique is substantially faster in terms of time computation and would appear to have certain important advantages over the other methods. © 1996 IEEE.

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