Torque Ripple in Switched Reluctance Motor Based on Asymmetrical Bridge Converter Pairote Thongprasri

Transcription

1 Internatonal Journal of Scentfc Research n Couter Scence, Engneerng and Inforaton Technology 017 IJSRCSEIT Volue Issue 5 ISSN : Torque Rle n Swtched Reluctance Motor Based on Asyetrcal Brdge Converter Parote Thongrasr Faculty of Engneerng at Srracha, Kasetsart Unversty Srracha Caus, 199, Sukuvt Road, Tungsukla, Srracha, Chonbur 030, Thaland ABSTRACT Ths aer resents an nvestgaton of the torque rle n 3-ase Swtched Reluctance Motor (SRM wth 1 stator oles and 8 rotor oles drven by the asyetrcal brdge converter. The otal control araeters are deterned to reduce torque rle by adjustng DC bus voltage and exctaton angles. A DSP TMS30F8335 controller s used to create the PWM and to calculate the rotor oston. The rotary torque nstruent s used to easure the otor torque at a rated load of 1.4 N. The exerental results, the torque rle deends on the ase current shae. The lowest torque rle wll be roduce when the ase current shae s flatted-to. Keywords : Swtched Reluctance Motor, Torque Rle, Asyetrcal Brdge Converter I. INTRODUCTION A Swtched Reluctance Motor (SRM s a doubly salent ole otor and no wndng or eranent agnet on the rotor. Therefore, there s no coer loss n the rotor. Advantages of the SRM, t has sle structure, robust, low cost, hgh ower densty, hgh relablty, good controllablty and hgh effcency. The SRM s wdely used for hgh-seed alcatons. However, a ajor dsadvantage of the SRM s the large torque rle, whch roduces acoustc nose and vbratons. The hghly non-unfor torque s roduced fro agnetc salency between stator oles and rotor oles [1]. Torque rle nzaton s ntroduced n [-4]. The ase current rofle s otzed and coared to constant the ase current rofle [5]. The torque dstrbuton functon technque can oderate the torque rle [6]. A syetrcal brdge converter s the ost oular toology used to drve a SRM. It conssts of two swtchng swtches and two freewheelng dodes er ase. Merts of a syetrcal brdge converter are hgh effcency, fast regeneraton, ase ndeendence, and hgh control caablty. Ths aer nvestgates the torque rle by adjustng DC bus voltage and exctaton angles. Ultately, the otal control araeters are deterned deendng on the ase current. II. PRINCIPLE OF SWITCHED RELUCTANCE MOTOR The voltage equaton ( v n Eq. (1 s forulated fro the electrc crcut of the stator col, whch s shown n Fg. 1. The crcut s current s. The col has an nductance L(,, whch s a functon of the rotor oston ( ( and current an nternal resstance ( R. v ( R L(,. Ths col has Fgure 1. Electrcal crcut dagra of the stator col CSEIT Receved : 01 Oct 017 Acceted : 09 Oct 017 Seteber-October-017 [(5: ] 651

2 v d(, R (1 n R dl d 1 L 1 (, ( (, The flux-lnkage s gven as L, ( ( Substtutng Eq. ( nto Eq. (1 n a, 1 1 1, d, d d (6 v R R d( L(, L(, d, L(, d d, R (3 d s the rotor angular seed; ( d, whch s substtuted n to (3. The yeld s v R L(, d, d (4 The voltage equaton n Eq. (4 conssts of 3 ters; the voltage equaton of nternal ase resstance R, ( the voltage equaton of ase nductance col d L(,, and the back EMF ( e equaton,, whch descrbes n Fg. (. d R L(, The torque equaton s gven as follows: T e a T e 1, d (7 where a s the echancal nut ower. The echancal equaton s gven by T d e TL J B (8 where T L s the load torque, J s the total nerta, and B s the total frcton coeffcent. III. ASYMMETRICAL BRIDGE CONVERTER The asyetrc brdge converter for 3-ase SRM s used as shown n Fg. 3. The converter conssts of two ower swtches and two dodes er ase. Each ase of the converter s ndeendent of others, so the external voltage control can be aled. v e External Source A B C Fgure. Electrcal crcut dagra of the SRM A B C Inut ower can be exressed as n, R L(, The Eq. (5 s solved and rearranged as follows; d (5 Phase A Phase B Phase C Fgure 3. 3-ase asyetrcal brdge converter The converter has three ossble odes of oeraton. When both swtchng devces are turn-on, the external voltage s aled and the current rses radly n the wndng. At low-seed oeraton, the current wll Volue Issue 5 Seteber-October UGC Aroved Journal [ Journal No : ] 65

3 exceed ts deanded value fast. When one swtch s turn-off and the current crculates through the other swtch and one dode. Ths oeraton s the called freewheelng ode, whch eloys a low deagnetzng voltage to the wndng. If both swtches turned off, the current crculates through two dodes and recharges the caactor. The deagnetzaton rocess s faster than the freewheelng ode. to botto. Table I IV suarze the value of average torque rle, when turn-on and turn-off angles were adjusted usng DC bus voltage at 1VDC, 4VDC, 36VDC, and 48VDC, resectvely. L a algned oston L u unalgned oston Rotor oston unalgned oston (ech. angle Fgure 4. Inductance rofle of the SRM (a angle at 0 and turn-off at 11 Fg. 4 dects the nductance versus dfferent rotor ostons. For controllng the SRM, the converter needs the aled voltage to the wndng between the turn-on angle and turn-off angle. The turn-on and turn-off dl angles ust be n range 0 to.5 or whle s d ncreasng. (b angle at 1 and turn-off at 11 IV. EXPERIMENTAL RESULTS The exerental setu s used to nvestgate torque rle, when the SRM s controlled by asyetrcal brdge converter. It conssts of 3-ase 1/8 SRM wth resolver, 3-ase asyetrcal brdge converter wth TMS8335DSP controller, external voltage source, torque eter, and 1.4 N load. (c angle at and turn-off at 1 (d angle at 3 and turn-off at 1 Fgure 5. Exerental setu To deterne the otu control araeters for lowest torque rle, Fgs. 6-9 show wavefors of average torque rle and ase current A-C (fro to (e angle at 4 and turn-off at Volue Issue 5 Seteber-October UGC Aroved Journal [ Journal No : ] 653

4 (f angle at 5 and turn-off at (d angle at 3 and turn-off at 1 Fgure 6. Adjustng /off angle wth 1VDC TABLE I CONTROL PARAMETERS WITH 1V ( ( (r Torque rle (N (e angle at 4 and turn-off at (f angle at 5 and turn-off at Fgure 7. Adjustng /off angle wth 4VDC TABLE II Control araeters wth 4V (a angle at 0 and turn-off at 11 ( ( (r Torque rle (N (b angle at 1 and turn-off at 11 (c angle at and turn-off at 1 (a angle at 0 and turn-off at 11 Volue Issue 5 Seteber-October UGC Aroved Journal [ Journal No : ] 654

5 TABLE III Control araeters wth 36V (b angle at 1 and turn-off at 11 ( ( (r Torque rle (N (c angle at and turn-off at 1 (a angle at 0 and turn-off at 11 (d angle at 3 and turn-off at 1 (b angle at 1 and turn-off at 11 (e angle at 4 and turn-off at (c angle at 4 and turn-off at (f angle at 5 and turn-off at Fgure 8. Adjustng /off angle wth 36VDC (e angle at 4 and turn-off at Volue Issue 5 Seteber-October UGC Aroved Journal [ Journal No : ] 655

6 (f angle at 5 and turn-off at Fgure 8. Adjustng /off angle wth 48VDC [4] V. P. Vujcc, Mnzaton of torque rle and coer losses n swtched reluctance drve, IEEE Trans. on Power Electroncs, vol. 7, no. 1, , 01. [5] J. B. Fort, B. Skala, and V. Kus, The torque rle reducton at the drve wth the swtched reluctance otor, IEEE Int. Power Electroncs and Moton Control, 015, DSa.16-1 DSa [6] X.D. Xue, K.W. E. Cheng, S.L. Ho, "Otzaton and evaluaton of torque-sharng functons for torque rle nzaton n swtched reluctance otor drves", IEEE Trans. on Power Electroncs, vol. 4, no. 9, 009. ( TABLE IV Control araeters wth 48V ( (r Torque rle (N. V. CONCLUSION Average torque rle value of the 3-ase 1/8 SRM usng the asyetrcal brdge converter s nvestgated. and turn-off angles were adjusted whle the DC bus voltage was fxed. Exerental results, the lowest torque rle wll be occurred, when the shae of ase current s flatted-to as shown n Fgs Ultately, the otal control araeters used to control the SRM that the shae of ase current s flatted-to. In ths aer, the otal turn-off angle s at 11 and the otal turn-on angle s at 0 or 1. VI. REFERENCES [1] I. Husan, Mnzaton of Torque Rle n SRM Drves, IEEE Trans. Industral Electroncs, vol. 49, no. 1, 00. [] C. H. Cho, S. H. K, Y. D. K, and K.H. Park, A new torque control ethod of a swtched reluctance otor usng a torque-sharng functon, IEEE Trans. on Magnetcs, vol. 38, no. 5, , 00. [3] Q. Zhan, J. Sun, S. Wang and K. Xn, A Fxed- Frequency Drect Instantaneous Torque Control Method of Swtched Reluctance Motor Contrbutng to Low Vbraton and Acoustc Nose IEEE Int. Conf. on Industral Electroncs, 006, Volue Issue 5 Seteber-October UGC Aroved Journal [ Journal No : ] 656