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단상 유도전동기의 무부하손실을 고려한 등가회로 정수의 결정
좌종근(Chong-Keun Jwa),김도진(Do-Jin Kim) 대한전기학회 2010 전기학회논문지 P Vol.59 No.4
This paper proposes a step-by-step method of determining the parameters of equivalent circuit which is considered the no load losses for the single phase induction motor which has the starting winding. This method is comprised of three steps, and the stator resistance which is measured by the method of voltage drop is treated as constant and the stator and the rotor leakage reactances are assumed to be the same in every step. The test results of no load and locked rotor test are used in the 1st and 2nd step, and the ratings of name plate of the motor are needed in the 3rd step. In the 1st step, the traditional equivalent circuit parameters are directly calculated by no load and locked rotor conditions. In the next step, five nonlinear simultaneous equations for five unknown parameters can be set up by no load and locked rotor equivalent circuits. These equations are solved by using the initial parameters obtained by the 1st step parameters. In the final step, three nonlinear simultaneous equations for rotor winding resistance, leakage reactance and no load losses component resistance can be set up by equivalent circuit under the rated operation. Three parameters are solved by using the 2nd step parameters. Thus, equivalent circuit parameters are gradually refined step by step. The validity of the proposed method is evaluated by comparing the computed values obtained by the equivalent circuit parameters with the experimental values of the load test.
등가회로법에 의한 커패시터 구동 단상 유도전동기의 특성해석
좌종근(Chong-Keun Jwa),김호민(Ho-Min Kim),김도진(Do-Jin Kim) 대한전기학회 2011 전기학회논문지 P Vol.60 No.4
This paper proposes a straightforward method of analyzing the operation characteristics for the capacitor run single-phase induction motor from the traditional equivalent circuit based on the revolving field theory. The proposed method consists of five procedures as follows: mechanical loss segregation, iron loss segregation and calculation of the equivalent circuit parameters, recalculation of parameters of the main winding side, calculation of the auxiliary winding magnetizing reactance and effective turn ratio, and analyzing the operation characteristics for this motor. When the characteristics are analyzed, the segregated mechanical and iron losses are considered as a loss resistance across input terminals of the equivalent circuit for the analysis. The validity of the proposed method is verified from the comparison between the computed results and the experimental ones for the operation characteristics.
姜尙秀(Sang-Su Kang),左宗根(Chong-Keun Jwa) 대한전기학회 2008 전기학회논문지 P Vol.57 No.4
This paper analyzes the operation characteristics of a self excited induction generator with Steinmetz connection. For this analysis, the symmetrical components analysis is used to obtain the related expressions and the excitation capacitance and the magnetizing reactance are determined in tum by the condition of self excitation which includes the input impedance of the generator as viewed across load terminals. Two simultaneous equations of the condition of self excitation itself are solved by using the real and imaginary function in an application software. This method is applied to simulate the operation characteristics when the generator is driven at rated speed and the specified excitation capacitor is connected across the lagging phase. The results show that better operation characteristics except generated frequency are obtained by using relatively large excitation capacitance and resistive load.
金度進(Do-Jin Kim),左宗根(Chong-Keun Jwa) 대한전기학회 2008 전기학회논문지 P Vol.57 No.1
This paper describes a simple and straightforward method to determine phase converter reactances for the monocyclic start induction motor which have two different phase converters. In order to determine two reactances, two kinds of simultaneous equations with two unknown reactances at a specified speed are set up by the condition of balance operation. From these equation, these unknown reactances can be solved directly using the application software without any algebraic calculation. The applicability of this method is investigated by comparing with the known method by using the computed results at the starting and rated speed, and the results show good agreement each other. Using these results, the performance characteristics of this motor are computed and compared with three phase balance operation of induction motor.
金度進(Do-Jin Kim),左宗根(Chong-Keun Jwa) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
This paper analyzes the losses of a Steinmetz connection three-phase induction motor which is supplied by a single-phase source. The T-type equivalent circuit which is taken no-load losses into account is used to determine phase converter capacitive reactances at starting and rated speed by using the condition of the minimum voltage unbalance. The starting and the operating capacitor are replaced at the slip of the same voltage unbalance factor points which are depicted using two capacitive reactances. The operation characteristics are investigated by comparing with those of three-phase balanced operation to find the feasibility of single-phase operation. To analyze the losses of this motor, the output power decrease factor(OPDF), the loss ratio(LR), the no load loss ratio(NLLR), the copper loss ratio(SCLR), the stator copper loss ratio(SCLR), and the rotor copper loss ratio(RCLR) are defined and simulated in the whole slip range. The simulated results show that OPDF is maintained almost uniformly, LR is low at low speed and high at high speed, CLR is higher than NLLR, but CLR varies concavely and NLLR varies convexly at high speed, SCLR is low at low speed and high at high speed, but SCLR varies convexly at high speed, and RCLR is nearly opposite to SCLR.