Basic Study of Radial Distributions of Electromagnetic Vibration and Noise in Three-Phase Squirrel-Cage Induction Motor under Load Conditions

Transcription

1 54 Journal of International Conference on Electrical Machine and Sytem Vol. 2, No. 2, pp. 54 ~58, 203 Baic Study of Radial Ditribution of Electromagnetic Vibration and Noie in ThreePhae SquirrelCage Induction Motor under Load Condition Iao Hirotuka*, Kazuo Tuboi* and Youuke Takahahi** Abtract Reduction of electromagnetic vibration and acoutic noie from threephae quirrelcage induction motor (IM) i very important, particularly from the tandpoint of environmental conideration. Although the electromagnetic vibration of IM ha been tudied for everal year, the relationhip between the radial ditribution of the electromagnetic vibration and noie and the electromagnetic force reponible for them have not yet been analyzed in ufficient detail. In the preent tudy, we invetigated thi relationhip experimentally for a mall IM under different load condition. Our reult clearly how that the radial ditribution of the dominant electromagnetic vibration and noie component match the mode hape of the dominant electromagnetic force producing thee component. Keyword: Induction motor, Noie, Vibration, Harmonic flux.. Introduction In recent year, the demand for induction motor (IM) with low noie characteritic ha increaed coniderably owing to environmental conideration. The baic concept of IM have been clarified through numerou tudie []. However, the relationhip between the radial ditribution of the electromagnetic vibration and noie and the force wave reponible for them have not yet been analyzed in ufficient detail. In thi paper, we preent the reult of an experimental invetigation into the radial ditribution of the electromagnetic vibration and noie generated by an IM under variou load condition. Firt, we lit the occurrence frequency and mode of the dominant electromagnetic force generated by the interaction of the harmonic fluxe in the IM gap. Next, we decribe the experimental method. Finally, on the bai of the reult from everal trial, we how that the radial ditribution of the dominant electromagnetic vibration and noie component clearly correpond to the mode hape of the dominant electromagnetic force. 2. Dominant Electromagnetic Force The general equation for the dominant electromagnetic * Department of Electrical Engineering, Chubu Univerity, Japan ** Tohiba Indutrial Product Mfg., Japan Received 08 April 203 ; Accepted 30 April 203 force reponible for the dominant electromagnetic vibration and noie component are derived in [2]. Table ummarize the occurrence frequency f M (Hz) and mode M of the dominant electromagnetic force in an IM driven by a inuoidal power upply, where n and n denote the number of tator and rotor lot, repectively; p' denote the number of pole pair; denote the lip; f denote the frequency of the power upply; and L and K are integer indicating the order of the tator and rotor lot permeance, repectively. For convenience, the dominant force are allocated a claification number. Thi table alo how that two type of electromagnetic force [I] and [II] are produced under different load condition. Force [I] i generated by the interaction between the tator fundamental flux and the rotor harmonic flux under both no load and load condition, wherea force [II] i generated by the interaction between the tator harmonic flux and the rotor fundamental flux only under load. Table. Occurrence frequency and mode of dominant Claification number Frequency f v Mode M [I] ( p' ) + ( p' + Ln Kn ) ( ) Kn p' 2 f + Ln Kn) + ( p ') 2 ( ) Kn p' f [I] ( p ) ( p ± Ln m Kn ) ' ' ± Ln m Kn) ( p ') [I] ( p' ) + ( p' Ln + Kn ) 3 ( ) Kn p' + 2 f Ln + Kn) + ( p ')

2 Iao Hirotuka, Kazuo Tuboi and Youuke Takahahi Tet Motor and Meaurement A motor (pecification lited in Table 2) with 36 and 33 tator and rotor lot, repectively, wa ued a the tet motor; thi lot combination i not ued commercially but implifie examination of the dominant electromagnetic vibration and noie. A inuoidal voltage of variable frequency wa upplied, and the natural frequencie of the tet motor were meaured by uing an impact hammer at the ame motor temperature a that for the meaurement of the electromagnetic vibration and noie. It wa confirmed that the natural frequencie of the tet motor were approximately contant even if the rotor were replaced. Noie meaurement were conducted in a motor noie laboratory in which reflected ound and background noie were minimized (Fig. 2). The tet motor wa et on an eddy current dynamometer with a damper rubber to minimize the effect of external vibration. To avoid abnormal tarting phenomena in the tet motor and to adjut the upplied frequency f, a ine wave variable frequency power upply wa ued. The radial vibration wa detected by two accelerometer: one fixed on top of the IM, and the other, movable. The ignal from thee accelerometer were input into a fat Fourier tranform (FFT) analyzer through charge amplifier. Electromagnetic noie wa alo detected by two device: a fixed microphone mounted at the upper center poition on the IM tator and a movable microphone. The meaured ound preure level (db) were analyzed by the FFT analyzer via ound level meter. Finally, to etimate the electromagnetic noie in better detail, the ditance between the center of the tet motor and both microphone wa 0.5 m, which i le than the tipulated ditance in JIS C 420 [3]. Table 2.Specification of tet motor Number of pole: 2p 4 Rated output.5 kw Rated voltage 200 V Rated frequency 60 Hz Number of tator lot n 36 Number of rotor lot n 33 Skew of rotor lot No kew 506, 043, 344, 684, Main natural frequencie 956, 2653, 333, 3806 Hz Meaurement of vibration and noie were performed at no load (i.e., when the percentage of the load to the rated load, Lp i 0%) and rated load (Lp = 00%). When Lp i changed, the occurrence frequency of the vibration and noie component, fm i varie becaue of the change in lip. To eliminate the effect of the mechanical ytem and keep fv contant, the voltage/frequency ratio V/f wa kept at 200/60 while adjuting either V or f. Further, when force 2 in Table I i the caue of vibration and noie component, fm can be maintained at contant value by adjuting V/f and keeping the rotational peed at 800 min to avoid the effect of the natural frequency. 4. Experimental Reult 4. Dominant Electromagnetic Vibration and Noie Component A hown in Fig., fv decreae with an increae in the load becaue of the accompanying increae in lip. Moreover, the figure clearly how that the dominant electromagnetic noie component ha the ame frequency a the dominant electromagnetic vibration component. In thi paper, the five component lited in Table III are conidered to decribe the radial ditribution, which are dicued in the next ubection. A ummarized in Table III, the dominant component correpond to the force with mall mode M (Table I). In particular, 09 Hz and 200 Hz are dominant at Lp = 0% becaue they correpond to force with M = and 2, repectively. 4.2 Radial Ditribution of Dominant Electromagnetic Vibration and Noie Component Fig. 4 how the radial ditribution of the 99 Hz (= 6.5f) vibration and it noie component at any intant at Lp = 0%. Thee ditribution are imilar to each other and correpond to M = 3, a hown in Table III. Fig. 5 how the correponding ditribution at Lp = 00%. In thi figure, the rotational direction of the node i alo indicated. Thee ditribution alo appear to correpond to M = 3. Thu, from Fig. 4 and 5, it i oberved that the ditribution of the electromagnetic vibration and noie component do not change form regardle of the load. Fig. 6, 7, 8, and 9 how the radial ditribution of the 09 (8.5f), 978 (33f), 200 (35f), and 3088 Hz (5.5f) vibration and noie component at any intant. Thi control can regulate capacitor voltage to the reference value per arm module Table 3. Dominant electromagnetic vibration and noie component f v at L p = 0% M K L 990 (6.5f) 3 09 (8.5f) 978 (33f) (35f) (5.5f) 5 3 3

3 56 Baic Study of Radial Ditribution of Electromagnetic Vibration and Noie in ThreePhae SquirrelCage Induction Motor under Load Condition 4. Concluion We invetigated the radial ditribution of the vibration and noie of an IM under different load condition. Our experiment confirmed that a cloe relationhip exit between the radial ditribution of the electromagnetic vibration and noie component and the radial force. We believe that the reult of our tudy can ait in noie and vibration reduction for IM. And the control can regulate capacitor voltage to the reference value per arm module Diplacement 0 2 ± (μm) 0 8 at bae time 2 after /99 /2 () 3 after /99 2/2 () 4 after /99 3/2() 5 after /99 4/2 () 6 after /99 5/2 () 7 after /99 6/2 () 8 after /99 7/2 () 9 after /99 8/2 () 0 after /99 9/2 () after /99 0/2 () 2 after /99 /2 () (a) Electromagnetic vibration Sound preure level (kg/m 2 ) at bae time 2 after /99 /2 () 3 after /99 2/2 () 4 after /99 3/2() 5 after /99 4/2 () 6 after /99 5/2 () 7 after /99 6/2 () 8 after /99 7/2 () 9 after /99 8/2 () 0 after /99 9/2 () after /99 0/2 () 2 after /99 /2 () (b) Electromagnetic noie. Fig.. Radial ditribution of 99 Hz (6.5f) component at Lp = 0%

4 Iao Hirotuka, Kazuo Tuboi and Youuke Takahahi 57 Accelerometer Eddy current dynamometer Tet motor Microphone Fig. 2. Experimental apparatu Vibratory acceleration fa [m/ 2 ] Hz,.2 m/ 2 09 Hz, 2.90 m/ 2 L p = 0%, f = 60 Hz, Poition: 978 H z, 200 Hz,.20 m/ 2.9 m/ Hz,.35 m/ Hz, 2.98 m/ Hz, 2.0 m/ 2 Lp = 00%, f = 60 Hz, Poition: 89 Hz, 0.74 m/ Hz, 7.60 m/ Hz, 0.62 m/ 2 Fig f component at Lp = 00% Occurrence frequency (khz) (a) Electromagnetic vibration Sound preure level Sp [db] Hz, 49.2 db 09 Hz, 60.9 db 978 Hz, 200 Hz, 72.3 db 45.6 db 3088 Hz, 55.4 db 944 Hz, 65.9 db 063 Hz, 76.5 db 89 Hz, 40.7 db Lp = 0%, f = 60 Hz, Poition : 0 Lp = 00%, f = 60 Hz, Poition: 203 Hz, 72.8 db 2956 Hz, 30.9 db Fig f component Occurrence frequency (khz) (b) Electromagnetic noie Fig. 3. Dominant electromagnetic vibration and noie at Fig f component (Continued)

5 58 Baic Study of Radial Ditribution of Electromagnetic Vibration and Noie in ThreePhae SquirrelCage Induction Motor under Load Condition Reference [] For example, S. J. Yang, LowNoie Electrical Motor, Clarendon Pre, Oxford, 98. [2] K. Tuboi, I. Hirotuka, F. Ihibahi, Caue and Characteritic of the Electromagnetic Vibration of a Squirrel Cage Induction Motor under Load, Tran. IEEJ, Vol. 7D, No., pp. 7380, January 997. [3] Japanee Indutrial Standard Committee, JIS C 420, 200 (in Japanee). Fig f component Iao Hirotuka (Member of I.E.E.J) i a profeor at Chubu Univerity, College of Electrical Engineering, Department of Electrical Engineering. He received a Mater of Engineering degree in 986 from Chubu Univerity. He worked for Mitubihi Electric Corporation from April to Augut 986. He received hi Doctor of Engineering degree in 990 from Chubu Univerity. Hi major reearch i on rotating electrical machine, with pecial emphai on abnormal phenomena in induction machine. He i a member of IEEE, the Japan Society of Applied Electromagnetic and Mechanic, Intitute of Noie Control Engineering of JAPAN, and of the Intitute of Electrical Intallation Engineer of Japan. Kazuo Tuboi (Senior Member of I.E.E.J) i a profeor at Chubu Univerity. He received hi Mater degree in 973 from Chubu Intitute of Technology (now Chubu Univerity), and hi Doctor of Engineering degree in 976 from Kyuhu Univerity. Hi reearch interet are in the field of power, electric drive, and control ytem. Hi major reearch i on rotating electrical machine. He received a Paper Award from the Intitute of Electrical Engineering of Japan (IEEJ). He i a member of IEEE, and of the Intitute of Electrical Intallation Engineer of Japan. Fig f component 5. Acknowledgment The author thank the graduate tudent of the Department of Electrical Engineering, College of Engineering, Chubu Univerity, for their aitance. Youuke Takahahi (Member of I.E.E.J) received a Mater of Engineering degree in 2002 from Chubu Univerity. He joined Tohiba indutrial product Manufacturing Corporation in He i mainly engaged in development and deign of induction motor.