無刷直流電機控制器的軟件設(shè)計中英文翻譯

1、Commutation Torque Ripple Reduction in BLDC Motor Using PWM_ON_PWM ModeGuangwei Meng, Hao Xiong, Huaishu Li Department of Electrical Engineering, Naval University of Engineering, Wuhan, China.Abstrac t:The paper analyzes the steady commutation process of the BLDC motor using PWM mode, confirms the c

2、ommutation time to keep noncommutation phase current amplitude constant during commutation period by way of PWM in the period to implement the compensation control to eliminate commutation torque ripple under both low speed and high speed operation, investigates the effect by PWM mode on a three-pha

3、se six-state 120turn-on° BLDC motor, and presents torque ripple compensation control in PWM_ON_PWM mode, which can not only entirelyeliminate torque ripple resulted from the current emerging in the turn-off phase during non-commutation period but also compensate torque ripple caused by the comm

4、utation current during commutation period.Index TermsBLDC motor, commutation, PWM, torque ripple.I. INTRODUCTIONThe BLDC motors have been widely used due to its features - a simple structure, good speed adjusting performance,high power density, low noise and simple control, etc. It is a hotspot to s

5、uppress the torque ripple and improve the control performance of a BLDC motor with the trapezoidal back emf.BLDC motors usually operate in all kinds of PWM modes, which not only affect the dynamic loss of power switches and radiation uniformity, but also influence the torque ripple. It is an effecti

6、ve way to suppress the torque ripple through changing dc bus chopper control to remain non-commutation phase current amplitude constant, but it results into a more complex topology 1-3. It is just fit for low speed applications tocontrol non-commutation phase current amplitude to regulate the commut

7、ation torque ripple . It is analyzed about the influence resulted from PWM ON mode on the torque ripple .The ideas in 1-3 are to adopt different suppression methods in different speedinterval, but they don t take t he effect by PWMsonmodethesystemin account. The predictive current, neural network co

8、ntrol and active disturbance rejection control etc are introduced to suppress the torque ripple , but the control algorithm is more complicated and harder for realization.Depending on the commutation process of BLDC motors and the effect by PWM modes on the system, thepaper presents a torque ripple

9、com-pensation control in PWM_ON_PWM mode at different speeds by seeking different PWM modulation ratios during commutation period as motor runs at low speed and high speed.The method retains the original to-pology, improves the control performance of the system dramatically,and moreover is easy to r

10、ealize.II. ELECTROMAGNETIC TORQUE OF BLDC MOTOR DURING COMMUTATION PROCESSAssume that the BLDC motor is three-phase symmetrical and Y- connected, and neglect eddy currents and hysteresis losses, its equivalent circuit and main circuit are shown in Figure 1. r, L are the resistance andinductance of t

11、he stator windingsrespectively;C B A e e e , are the counter emfs of the corresponding phase windings respectively; C B A i i i , are the corresponding phase currents respectively.0=+C B A i i i (1The counter emf of every phase winding is a trapezoidal waveform with a flat-top width greater than or

12、equal to 1200 electrical degree,and its flat-top amplitude is Em. When the motor works in three-phase six-state1200 turn-on mode, the currents don t commutates instantaneously as a result of theinductanceof the armature winding. Take the power switch T1 and 2T s turn-on to2T and 3T s turn-o for exam

13、ple. During the commutation, it is gained as follows m C B A E e e e =-= (2Suppose that the mechanical angular velocity of the rotor is , the toque can beobtained as follows during the commutation process.= +=C m C C B B A A e i E i e i e i e T 2 (3 It is obvious from (3 that the toque is proportion

14、al to the non-commutation phase current during commutation,i.e. the commutation torque ripple can be eliminated so long as non-commutation phase current remains constant during commutation. III TORQUE RIPPLE REDUCTION IN PWM MODEa new PWM mode is presented -PWM _ON _PWM, i.e. using PWM mode in the f

15、irst30 and° the last 30 while° keeping constant turn-onmode in the middle 60 . The°mode can entirely eliminate the emerging current in the turn-off phase during non-commutation and thus reduce the torqueripple during non-commutation.PWM _ON _PWM is a bilateral modulation, but the dyna

16、mic losses of power switches in the mode are equal to those of unilateral modulation. Six switches are modulated in turn, so the power switches have a uniform radiation and the system has a higher reliability. The mode is employing PWM on the turn-on power switchesand thus it can suppress the torque

17、 ripple during commutation to a certain extent even if a compensation control is not applied at a low speed.In PWM _ON _PWM mode, it can not only eliminate the torque ripple during non-commutation but also suppress the commutation torque ripple at low speed operation by keeping dm BB U rI E D 034+=

18、in the commutation compensation control time ? ? +=m c E rI rI r L t 21ln 00 at low speed operation, i.e.d m U rI Ehigh speed operation i.e.d m U rI E +034,overlapping commutation is used to keep the turn-on phase constantly on and make the control pulse duty cycle of the turn-off phase 1340-+=dm AA

19、 U rI E D in the commutation compensation control time? ? -=0021ln rI E U rI r L t m d c ,which can not only eliminate the torque ripple during noncommutation but also suppress the commutation torque ripple at high speed operation.A simulation is carried out to verify the method.The parameters areN

20、T m r n V U m kg J r mH L L N N 4.0,1600,48,0157.0,66.0,262=? = =.In non-full-bridge modulation mode such as H_PWM-L_ON mode, power switches in the upper arms use PWM mode while the others in the lowerarms use constant turn-on mode in 1200 turn-on interval. The simulation waveform of phase current i

21、s shown in Fig. 3. It is obvious that a current emerges in the turn-off phase during non-turn-on period and its pulsating frequency is the same as the modulatingfrequency while its amplitude varies with the variation of back emf amplitude, whichproduces a reverse torque.Figure 2 H_ PWM - L_ ON phase

22、 current waveform Figure 3 PWM_ON_PWM phase current waveform The simulation waveform of phase current in PWM _ON _PWM mode is shown in Fig.4. It is obvious that no current emerges in the turn-off phase duringnon-turnon period, which reduces the torque ripple during noncommutation compared with other

23、 PWM mode.Fig.5 shows the waveforms of the phase current and torque at low speed with PWM pulse duty cycle DA=0.2 without compensation control. Fig. 6 shows thewaveforms of the phase current and torque at low speed with the control pulse duty cycle DBB=0.4 in the turn-on phase within the commutation

24、 time tc=0.0013 by a compensation control. The comparison indicates that the torque ripple caused by commutation can be almost eliminated by means of a commutation compensationcontrol at low speed application.It is found from Fig.3 to Fig.8 that using a commutation compensation control in PWM_ON_PWM

25、 mode can not only avoid the torque ripple caused by the emerging current in the turn-off phase during noncommutation but also effectively suppress the commutation torque ripple at both low speed and high speed applications.Figure4 phase current and torque waveform during Figure 5 when running at lo

26、w speed by changing theLow speed running phase current and phase compensation torque waveformFigure 6under the speed of phase current and torque waveform Figure 7high-speed run through the compensation control ofphase current and torque waveformIV. CONCLUSIONSBased on the analysis of commutation pro

27、cess of BLDC motor and the effect by PWM mode on the control system, a commutation compensation control in PWM_ON_PWM mode is worked out, which can not only eliminate torque ripple resulted from the current emerging in the turn-off phase during non-commutation period but also compensate commutation

28、torque ripple. A control system without torque ripple can be realized through the method under both low speed and high speed operation.REFERENCES1 S. Wang, T. Li, and Z. Wang,DC motor drives using a single current sensor,12,pp. 288-293, March. 2008.“ Commutation torque ripple reduction in brushless

29、” Electric Machines and Control, vol.2 X. Zhang and Z. Lü ,“ New BLDCM drive method to smooth the torque,” PowerElectronics, vol. 41, pp. 102-104, Feb. 2007.3 H.J. Song and C. Ick.“ Commutationippletorquereduction in brushless DCmotor drivers using a single DC current sensor,” IEEE Trans. On Po

30、wer Electr, vol.19,pp. 312-319, Feb. 2004.4 G.H. Kim, J. Seog and S.W. Jong, “ Analysis of the commutation torque ripple effect for BLDCM fed by HCRPWM-VSI , ” Proc. of APEC 92, 1992, -pp284.277.5 X. Zhang and B. Chen, “ The different influences of four PWM modes on commutation torque ripples in bru

31、shless DC motor control system, ” Electric Machines and Control,vol.7, pp. 87-91, Feb. 2003.6 D. Chen, Z. Liu and J. Ren et al, ?Analysis of effects onBLDCM torque ripple by PWM modes,” . Electrical Drivers, vol.35, pp. 18-20, April 2005.中文翻譯用 PWM_ON_PWM 模式抑制無刷直流電機換相引起的脈動轉(zhuǎn)矩中國武漢海軍工程大學(xué)電機工程系蒙廣偉、雄郝、李懷樹編

32、摘要 :本文分析了無刷直流電動機采用 PWM 控制穩(wěn)定換相的過程 ,證實了運用 PWM 模式 ,在換相時控制非換相相電流有穩(wěn)定不變的幅度 ,并進行補償以消除低速和高速工作下的換相轉(zhuǎn)矩脈動 ;研究了運用三相六狀態(tài)的 PWM 模式 120°啟動無刷直流電機的方法 ,并提出基于脈寬調(diào)制的 PWM 模式如何來抑制轉(zhuǎn)矩脈動 ,PWM 控制不僅可以消除非換相期間由關(guān)斷電流引起的轉(zhuǎn)矩脈動 ,還可以補償換相期間由換相電流引起的轉(zhuǎn)矩脈動。關(guān)鍵詞 :直流無刷電機、換相、 PWM 脈寬調(diào)制、轉(zhuǎn)矩波動1.前言由于直流無刷電機具備結(jié)構(gòu)簡單、調(diào)速性能好、功率密度高、噪音低、控制簡便等優(yōu)點 ,現(xiàn)已得到廣泛的運用。

33、用梯形反電動勢法抑制轉(zhuǎn)矩脈動和完善直流無刷電機控制性能已成為一個熱點。直流無刷電機經(jīng)常運轉(zhuǎn)在各種 PWM 模式 ,PWM 不僅影響著電力開關(guān)的動態(tài)損耗和輻射均勻性 ,也影響著轉(zhuǎn)矩脈動。通過直流母線波紋斬波 ,抑制轉(zhuǎn)矩脈動以穩(wěn)定非換相相電流幅值恒定是很有效的方式 ,但這導(dǎo)致了一個更復(fù)雜的拓撲結(jié)構(gòu) 式(1式 (3,它只適用于低速運作場合 ,通過控制非換相相電流幅值來控制轉(zhuǎn)矩脈動。分析PWM 模式下轉(zhuǎn)矩脈動的作用 , 式(1式 (3中的觀點是在不同的速度區(qū)間采用不同的抑制方法 ,但沒有起到 PWM 的作用。目前預(yù)測 ,神經(jīng)網(wǎng)絡(luò)控制和主動自抗擾控制等的引入 ,能達到抑制轉(zhuǎn)矩脈動的效果,但控制算法更復(fù)雜

34、也更難實現(xiàn)。根據(jù)直流無刷電機換相問題和 PWM 調(diào)制方式在系統(tǒng)中的影響 ,提出了一種控制轉(zhuǎn)矩脈動補償模式 -PWM_ON_PWM 模式 ,尋求在不同的速度下通過尋求不同的 PWM 調(diào)制比 ,來保證電機在低速和高速狀態(tài)下穩(wěn)定轉(zhuǎn)動。該方法保留了原有的拓撲結(jié)構(gòu) ,顯著提高了該系統(tǒng)的控制性能 ,而且很容易做到。2.無刷直流電動機換相過程中的電磁轉(zhuǎn)矩圖 1 三相無刷直流電動機及其系統(tǒng)圖假設(shè)直流無刷電機是三相對稱 Y 聯(lián)接 ,忽略渦流和磁滯損耗 ,其等效電路和主要電路如圖 1 所示 ,R ,L 分別是電阻和定子繞組電感 ,C B A e e e ,分別是相應(yīng)階段的繞組反電動勢 ,C B A i i i ,

35、 分別是相應(yīng)的相電流 :0=+C B A i i i (1 每相繞組的反電動勢是平頂寬度大于或等于120 度的梯形波 ,其平頂振幅是 Em 。當電機工作在三相六階段 120 度導(dǎo)通模式下 ,電流不整流瞬間電樞繞組做電感處理。例如圖中 1T 和 2T 導(dǎo)通 ,到 2T 和 3T 導(dǎo)通。換相時有如下關(guān)系 :m C B A E e e e =-= (2 假設(shè)轉(zhuǎn)子機械角速度為 ,在換相過程中可獲得的轉(zhuǎn)矩如下: = +=C m C C B B A A e i E i e i e i e T 2 (3 很顯然 ,從式 (3 可以看出在換相期間轉(zhuǎn)矩與非換相相電流成比例關(guān)系,即只要換相時非換相相電流保持不變,

36、就可以消除轉(zhuǎn)矩脈動。3.PWM 模式降低轉(zhuǎn)矩脈動在公式的基礎(chǔ)上 ,一個新的 PWM 的控制方式 PWM_ON_PWM 模式提出了 ,這種控制方式是在第一個30 度和最后一個 30 度里采用 PWM 控制 ,同時保持轉(zhuǎn)速在中間的 60 度范圍內(nèi)不變。該模式可以完全消除在非換相期間關(guān)斷階段出現(xiàn)的電流波動 ,并減少非換相期間的轉(zhuǎn)矩波動。PWM_ON_PWM 模式是雙邊調(diào)制的 ,但單邊調(diào)制的電源開關(guān)動態(tài)損耗是相等的。六開關(guān)輪流調(diào)制 ,系統(tǒng)具有更高的可靠性。該模式運用 PWM 控制開啟電力開關(guān) ,因此即使補償并不適用于低速情況 ,它也可以在一定程度上抑制換相時的轉(zhuǎn)矩脈動在 PWM_ON_PWM 模式下

37、,不僅可以消除非換相期間的轉(zhuǎn)矩脈動 ,而且過低速時d m U rI E +034,通過控制換相補償時間? +=m c E rI rI r L t 21ln 00 來控制 dm BB U rI E D 034+=, 從而減少低速時的換相轉(zhuǎn)矩脈動。高速運轉(zhuǎn)時d m U rI E +034,采用換相重疊保持導(dǎo)通相不斷,通過控制換相補償控制時間? -=0021ln rI E U rI r L t m d c 來控制關(guān)斷相的脈沖占空比1340-+=dm AA U rI E D , 從而不僅消除了非換相期間的轉(zhuǎn)矩脈動,也抑制了高速運轉(zhuǎn)時的換相轉(zhuǎn)矩脈動。用仿真對該方法進行驗證,仿真參數(shù)如下 :N T m r

38、 n V U m kg J r mH L L N N 4.0,1600,48,0157.0,66.0,262=? = =在非全橋調(diào)制模式 ,如 H_PWM-L_ON 模式 ,上橋臂的電源開關(guān)用 PWM 模式 ,下橋臂采用120 度間隔的持續(xù)導(dǎo)通模式。相電流的仿真波形如圖3 所示 ,很明顯非導(dǎo)通期間的關(guān)斷相的有電流流過 ,且脈動頻率與調(diào)制頻率相同,電流幅度隨調(diào)制波幅度變化,這產(chǎn)生了一個反轉(zhuǎn)矩。圖 2 H_ PWM -L_ ON 的相電流波形圖 3 PWM_ON_PWM 的相電流波形圖 4 表示的是 PWM_ON_PWM 模式的相電流波形 ,很明顯非導(dǎo)通期間關(guān)斷相沒有電流流過 ,這與其他 PWM 模式相比 ,減少了非換相期間的轉(zhuǎn)矩脈動。圖 5 是占空比為 0.2 的無補償 PWM 控制 ,顯示了低速狀態(tài)下的電流和轉(zhuǎn)矩波形。圖 6 是占空比為 0.4,換相補償時間為 0.0013 的 PWM 控制 ,顯示了低速狀態(tài)下的電流和轉(zhuǎn)矩波形。通過比較可得 ,低速狀態(tài)下 ,通過換相補償 ,幾乎可以完全消除換相導(dǎo)致的轉(zhuǎn)矩脈動。從圖 3 到圖 8 可