Available online at www.ciencedirect.com Phyic Procedia 5 ( ) 53 59 International Conference on Solid State Device and Material Science Reearch on Direct Torque Control of Induction Motor Baed on TMS3LF47A Xu Lufei, Nan Guangqun School of Electrical and Electronic Information Engineering Huanghi Intitute of Technology Huanghi, Hubei Province, China Abtract The direct torque control of Induction Motor i one of the high performance control ytem, which wa propoed after the vector control cheme. During the recent year, It ha been developed rapidly for it concie ytem cheme, excellent dynamic and tatic performance. DTC ytem directly control the electromagnetic torque and tator flux, uing the analyzing method of pace vector and tator flux orientation. Thi paper etablihe the mathematical model of direct torque control (DTC) ytem of induction motor, and direct torque control (DTC) cheme of induction motor baed on TMS3LF47A i introduced. The control cheme get the witch control ignal of inverter with the pace voltage vector modulation technology. Finally the approach ha been implemented on DSP in a. kw drive. The reult how that the DTC with SVPWM ha many merit uch a imple realization, good running performance and high voltage utilization ratio. Publihed by Elevier Ltd. B.V. Selection and/or peer-review under reponibility of of [name Garry organizer] Lee Open acce under CC BY-NC-ND licene. Keyword: TMS3LF47A;SVPWM;direct torque control; induction motor;. Introduction Induction motor Direct Torque Control (DTC) method ha been developed rapidly for it concie ytem cheme, excellent dynamic and tatic performance. It olve ome important problem in large degree that computing complexity in vector control, peculiarity changed by the impact of motor parameter, actual performance i difficult to achieve analyi reult in theory. Direct torque control ytem adopt the method of pace vector analyi and field orientation of tator flux, take tator current and voltage through real-time detection to 3 / tranform, then directly the AC motor torque and flux can be calculated in tatic - coordinate ytem. According to the reult of controller output and location of the flux, look up optimal witch table, PWM ignal can be generated. Thi paper etablihe the mathematical model of direct torque control (DTC) ytem of induction motor. Then a realization cheme of fully digitized direct torque control ytem i introduced with TMS3LF47A that work a the core control chip and IPM 875-389 Publihed by Elevier B.V. Selection and/or peer-review under reponibility of Garry Lee Open acce under CC BY-NC-ND licene. doi:.6/j.phpro..3.9
54 Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 that work a main circuit. The control cheme obtain the witch control ignal of inverter with the pace voltage vector modulation technology. The ytem hardware and oftware tructure are preented in thi paper. The tet reult how that the DTC with SVPWM ha many merit uch a imple realization, good running performance and high voltage utilization ratio.. Control principle of Induction motor direct torque control and mathematical model DTC ytem tructure i hown in Figure, the main unit i contitute of rotate peed PI controller, torque PI controller, flux PI controller,the oberver of the tator flux linkage and the torque etc. In direct torque control ytem, how to control the tator flux linkage i a key and it can be deduced by model U - I, the relationhip between the tator flux linkage and the voltage u are hown a follow. The control ytem adopt ub-circular flux linkage trajectory in low-peed operation, thu enure the invariability of torque and flux linkage in low tator frequency. DTC voltage equation i u ri p u ri p () ur rr ir p r rr ur rr ir p r rr Stator Flux equation i ( u ri ) dt () ( u ri ) dt (3) arctan( / ) (4) In the formula are Repectively the component of the tator flux linkage in the, coordinate, i magnetic track phae angle., u u,, u u r, r are tator and rotor voltage baed on i i axi and are repectively the component of the tator current. In the formula 5, the electromagnetic torque of the induction motor i hown. 3 Te n p ( i i ) (5) Through formula () to (5), obervation value of the tator flux and electromagnetic torque can be calculated. After getting calculation reult, the tator flux and electromagnetic torque can be adopted cloed-loop control and the control ytem witch tate can be got through pace location of flux linkage and looking up witch table. When the inverter i on one of operation tate, the flux trajectory move along the direction of voltage vector that i correponding to the tate. The etimation of the tator flux rely on the tator reitance, and the deviation of the tator reitance will caue the unreaonable deviation of the tator flux, in order to olve the problem that the performance of the direct torque control ytem i poor when the motor at the low peed, thi paper put forward the fuzzy controller with the fuzzy reaoning algorithm and it can etimate the tator reitance.
Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 55 Fig. the DTC ytem diagram baed SVPWM 3. The compoition of the ytem and current detection The experiment ytem i built with the TMS3LF47 a the control chip and the intelligent module PMCAVJ6 a main circuit of the inverter. The hardware tructure diagram of the ytem wa hown in figure with TMS3LF47 a the mater component, it intruction cycle i 5n, with high reolution for PWM, and it can achieve complex calculation for real-time control. With two event management module EVA and EVB, It can achieve the 6 channel of the A/D converion, ymmetry and aymmetric PWM wave and dead zone programming etc. The chip HEDS - 566 i ued for peed detection, with the chip LF47A for it frequency of the coded orthogonal pule circuit by 4 time and with the timer for pule count, the feedback value of the peed can be obtained. The current enor LA8-P i ued for the tator current detection, A, B phae of the tator current ignal i ampling, amplified and filter before ent to the A/D port of the DSP proceor. The voltage enor LV8P i ued for the voltage detection, the value of the three-phae AC voltage can be obtained by meauring the voltage of the DC ide in main circuit. the witching frequency of the power module PMCAVJ6 Reach khz, it contitute of 6 IGBT unit and it integrated perfect drive circuit in internal, o it can achieve the function of the over current protection, overheating protection and the low voltage protection for the ytem. Current detection circuit i hown in fig.3.since the motor winding are ymmetrical, only two current which are i a and i b are detected. A i hown in fig.3, the current i a detected by the current Hall i ent to the ignal amplification circuit and then to full-wave rectifier whoe output i ent to the ampling pin ADCIN ( i b into ADCIN) of A/D converter in TMS3LF47A where the analog ignal i converted to the digital to be proceed.
56 Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 Fig. The hardware tructure diagram of the ytem iai R k R k C n RP R4 56k 56k +V C3 n 4 3 + - UA R3 TL84 3k C n -V R5 + 3k 3 - R6 3k k C4 4 R7 47p 4 UD TL84 D IN6 R8 k C5 u CMAX R9 k Ia Fig.3 current detect circuit 4. Principle of SVPWM and Software deign Space voltage vector implementation of control ytem adopt pace voltage vector modulation to form inverter witch ignal. It input ignal i V ref and V ref that i output ignal of flux and torque controller. At any moment, tator voltage vector hould fall on one of ix-voltage ector that i derived from baic voltage vector ditinction. In any PWM cycle T, dicretional tator voltage vector can be yntheized through two adjacent baic vector. A Fig4 hown, voltage vendor V ref i in the firt ector which i yntheized with two baic voltage vector V, V and two Zero vector V7,V8. The relation i:
Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 57 t t t t 7 3 v 3 v * * U dc (T T in( U dc T in t 3 ) t ) (6) (a) (b) Fig. 4 Space vector PWM * Calculated tep of Space Vector a follow:()voltage vector v compounded by calculation.()judging it phae according to v * angle of the interval. (3) Calculating working time of witching voltage vector. (4) Compounding three-phae PWM ignal according to working time of witch voltage vector. Control oftware i divided into two part, main program and interrupted ervice program. The main program goe on cycle after completing the initialization. All control proce i finihed in the interrupted ervice program. The interrupted ervice program mainly perform the ampling of motor tator current and voltage, finihing the converion of current, voltage, A / D converter, proceing peed feedback ignal through QEP unit, and output 6 channel PWM ignal ued to control baed on direct torque control algorithm. The ytem adopt timer T3 to trigger interruption every a ample cycle, thu enure to generate 6 channel PWM pule. 5. Experimental reult and concluion
58 Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 Experimental motor parameter i that power rating P N i.kw, tator rated voltage U N i 38V, tator reitance r i 3.66, tator current i.66a,tator inductance L i 36.6mH, rotor inductance Lr i 36.6mH, tator mutual inductance Lm i 96.6mH, rated peed n N i4r/min. The experimental reult are hown in Figure 5 to 8. From wave hown in thee figure, tranition time of the motor i hort, the motor peed rie from to 8 rpm in le than a econd time, and there are no overhoot, which fully reflect excellent acceleration performance of the direct torque control. From figure 6 to 7, in teady-tate current waveform and voltage waveform are ine wave with better quality. n * n Horizontal axi: 5m/div Vertical axi: 5rpm/div Fig.5 etting rotational peed n* and practical rotational peed n Horizontal axi: m/div Vertical axi: A/div Fig.6 tator current wave in table tate Fig.7 tator voltage wave in table tate
Xu Lufei and Nan Guangqun / Phyic Procedia 5 ( ) 53 59 59 Horizontal axi: 5m/div Vertical axi:.4web /div Fig.8, component of tator flux The DTC cheme i tudied in that uing TMS3LF47A DSP a the kernel of control ytem, and the oftware of control ytem complied in DSP aembly language. Stator flux oberver i key part of DTC ytem. Claic U-I model i imple. However the integrator inevitably bring up the error accumulation on DC drift at a low peed. So thi paper preent a new model baed on the tranform between low peed and high peed. In thi paper, we tudy the application of TMS3F47A in Direct Torque Control of Induction Motor Sytem. Uing SVPWM technology theory, harmonic i retrained by oftware deign, ignal generated i imple and convenient. Acknowledgment The author would like to acknowledge upport for the project from Key Dicipline on Automation &Electronic Engineering of Huanghi Intitue of Technology.. Reference [] M. F. Ecalante, J. C. Vannier, A. Arzande. Flying capacitor multilevel inverter and DTC motor drive application. IEEE Tran. Ind. Electron.,, vol. 49, no. 4, 89~85 [] Joon Hyoung Ryu, Kwang Won Lee, Ja Sung Lee. A Unified Flux and Torque Control Method for DTC-Baed Induction-Motor Drive. IEEE Tranaction on Power Electronic, Vol.,No.,January 6:34~4 [3] Maao Yano, Michio IwahoriTranition from Slip-Frequency Control to Vector Control for Induction Motor Drive of Traction Application in Japan Power Electronic and Drive Sytem 3. PEDS 3. The Fifth International Conference on Volume, 7~ [4] Wang Huangang,Xu Wenli,Yang Geng,et al. Anew approach to direct torque control of induction motor[j].proceeding of the CSEE,4,4():7~ [5] Liu Heping. DSP tructure, principle and application of TMS3LF4x [M]. Beijing: Beijing Univerity of Aeronautic and Atronautic Pre,