方成輝 陳 昊 Galina Demidova Alecksey Anuchin Yassen Gorbounov
開(kāi)關(guān)磁阻電機(jī)無(wú)電流傳感器控制方法
方成輝1,2,3陳 昊1,2,3Galina Demidova4Alecksey Anuchin5Yassen Gorbounov6
(1. 中國(guó)礦業(yè)大學(xué)電氣工程學(xué)院 徐州 221116 2. 新能源電動(dòng)車(chē)技術(shù)與裝備中東歐國(guó)家國(guó)際聯(lián)合研究中心 徐州 221008 3. 江蘇省高校新能源發(fā)電與電動(dòng)車(chē)國(guó)際合作聯(lián)合實(shí)驗(yàn)室 徐州 221008 4.圣彼得堡國(guó)立信息技術(shù)、機(jī)械和光學(xué)研究型大學(xué)控制系統(tǒng)與機(jī)器人工程學(xué)院 圣彼得堡 197101 5. 莫斯科動(dòng)力工程學(xué)院(國(guó)立研究型大學(xué))電力傳動(dòng)系 莫斯科 111250 6. 索菲亞地礦大學(xué)采礦生產(chǎn)自動(dòng)化系 索菲亞 1700)
電流傳感器的使用會(huì)增加系統(tǒng)的成本和噪聲干擾,降低系統(tǒng)的可靠性。而對(duì)于開(kāi)關(guān)磁阻電機(jī)系統(tǒng),缺少電流信號(hào)難以保證良好的控制性能。針對(duì)該問(wèn)題,提出一種無(wú)電流傳感器控制方法。該方法采用速度、加速度雙閉環(huán)控制,因此反饋量均由位置傳感器得到。首先,從兩個(gè)方面分析了所提出控制方法的可行性:①證明了該方法的收斂性;②證明了在穩(wěn)態(tài)下加速度和電磁轉(zhuǎn)矩的近似線性關(guān)系,并依此分析了加速度控制和轉(zhuǎn)矩控制的等效性。根據(jù)電機(jī)的磁鏈特性,對(duì)加速度環(huán),提出具有三個(gè)滯環(huán)邊界的滯環(huán)控制方法。兼顧電機(jī)效率和轉(zhuǎn)矩脈動(dòng),合理地選擇了開(kāi)通角、關(guān)斷角。實(shí)驗(yàn)電機(jī)為12/8開(kāi)關(guān)磁阻電機(jī)。分別采用電壓斬波控制方法、直接轉(zhuǎn)矩控制方法和所提出的控制方法運(yùn)行電機(jī),對(duì)其電流、電磁轉(zhuǎn)矩和轉(zhuǎn)速波形進(jìn)行了比較。結(jié)果表明,在控制效果上,所提出的控制方法與直接轉(zhuǎn)矩控制方法相當(dāng),優(yōu)于電壓斬波控制方法。除此之外,電流與電磁轉(zhuǎn)矩呈復(fù)雜的非線性關(guān)系,直接轉(zhuǎn)矩控制方法需要進(jìn)行電流和電磁轉(zhuǎn)矩的換算。而由于加速度與電磁轉(zhuǎn)矩的近似線性關(guān)系,所提控制方法無(wú)需計(jì)算電磁轉(zhuǎn)矩,因此計(jì)算量更小。
開(kāi)關(guān)磁阻電機(jī) 無(wú)電流傳感器控制方法 加速度 電磁轉(zhuǎn)矩
對(duì)于閉環(huán)控制系統(tǒng),控制變量必須是已知的,控制變量主要通過(guò)傳感器測(cè)量獲得。傳感器的使用存在以下弊端:①增加了系統(tǒng)的成本和體積;②安裝需要增加接線,帶來(lái)了電路干擾,降低了系統(tǒng)可靠性;③受環(huán)境約束,在惡劣條件下可能會(huì)失準(zhǔn)或失效[1-2]。因此,為了減少傳感器的使用數(shù)量,無(wú)傳感器控制技術(shù)正在被研究并已取得大量的成果[3-8]。
開(kāi)關(guān)磁阻電機(jī)結(jié)構(gòu)簡(jiǎn)單堅(jiān)固,其轉(zhuǎn)子通常采用硅鋼片疊壓制成,無(wú)繞組或永磁體,因此不存在開(kāi)、短路和退磁等問(wèn)題,可靠性高,適用于惡劣環(huán)境[9-13]。在惡劣環(huán)境中,無(wú)傳感器控制技術(shù)更為重要。開(kāi)關(guān)磁阻電機(jī)常用的控制方法包括角度位置控制(Angular Position Control, APC)[14-15]、電壓斬波控制(Voltage Pulse Width Modulation, VPWM)[16]、電流斬波控制(Chopping Current Control, CCC)[17-18]、直接轉(zhuǎn)矩控制(Direct Torque Control, DTC)[19-22]等。與異步電機(jī)、同步電機(jī)等電機(jī)相比,開(kāi)關(guān)磁阻電機(jī)主要缺點(diǎn)之一是具有較大的轉(zhuǎn)矩脈動(dòng)[23-24]。以上控制方法中,除APC和VPWM以外,其他方法都需要使用電流傳感器。APC和VPWM雖然不需要使用電流傳感器,但由于它們是單閉環(huán)控制,僅能跟蹤速度,對(duì)轉(zhuǎn)矩不具有控制能力。CCC能較好地控制電流,但由于電流和轉(zhuǎn)矩是非線性關(guān)系,對(duì)轉(zhuǎn)矩的控制效果不佳。DTC是直接跟蹤轉(zhuǎn)矩的控制方法,對(duì)轉(zhuǎn)矩控制效果好[19-22]。通常,DTC需要將電流值換算成電磁轉(zhuǎn)矩值跟蹤參考轉(zhuǎn)矩或者將參考轉(zhuǎn)矩?fù)Q算成參考電流值進(jìn)行電流跟蹤。因此,DTC除了需要每相電流值,還需要精確的電機(jī)模型參數(shù)。
開(kāi)關(guān)磁阻電機(jī)的電流傳感器通常安裝在每相繞組的端部。為了減少電流傳感器的使用數(shù)量,目前常見(jiàn)的方法是進(jìn)行傳感器的重構(gòu)[25-27]。不對(duì)稱半橋功率變換器(Asymmetric Half Bridge Converter, AHBC)是開(kāi)關(guān)磁阻電機(jī)最常用的功率變換器。它的工作方式是依次逐相導(dǎo)通。在換相區(qū)間,通常有兩相繞組同時(shí)導(dǎo)通。因此,任一時(shí)刻最多有兩相繞組上有電流。通過(guò)重構(gòu),電流傳感器與多相繞組耦合,任意時(shí)刻,先判斷工作相,再根據(jù)耦合系數(shù)矩陣,將傳感器上的電流值轉(zhuǎn)換成當(dāng)前工作相電流值。因此,電流傳感器重構(gòu)方法可以將電流傳感器的數(shù)量降至兩個(gè)[25-26]。文獻(xiàn)[27]對(duì)功率變換器和電流傳感器均進(jìn)行了重構(gòu),將電流傳感器的使用數(shù)量降至一個(gè)。對(duì)換相區(qū)的兩個(gè)工作相,該方法通過(guò)切換測(cè)量的方式獲取電流值。由于該方法不能測(cè)量退磁過(guò)程中的電流,因此通常用于CCC。
對(duì)于開(kāi)關(guān)磁阻電機(jī),在無(wú)電流傳感器的情況下,要保證良好的轉(zhuǎn)矩控制效果,需要找到一個(gè)新的不依賴電流的跟蹤變量,并且該變量與轉(zhuǎn)矩之間存在簡(jiǎn)單的函數(shù)關(guān)系?;诩铀俣茸兞?,本文提出一種無(wú)電流傳感器的開(kāi)關(guān)磁阻電機(jī)控制方法。首先證明了基于加速度閉環(huán)控制方法的收斂性并分析了加速度控制和轉(zhuǎn)矩控制的等效性。然后介紹了該控制方法的實(shí)現(xiàn)方式。最后通過(guò)實(shí)驗(yàn)比較了VPWM、DTC和該控制方法的控制效果。
對(duì)任何一種開(kāi)關(guān)磁阻電機(jī)的控制方法,轉(zhuǎn)子位置和轉(zhuǎn)速都必須是已知的。它們通常由位置傳感器測(cè)得,能夠通過(guò)位置傳感器直接或間接測(cè)得的量為轉(zhuǎn)子位置及其階導(dǎo)數(shù)。轉(zhuǎn)子位置的一階導(dǎo)數(shù)為轉(zhuǎn)速,二階導(dǎo)數(shù)為加速度,三階及以上導(dǎo)數(shù)無(wú)物理意義。當(dāng)系統(tǒng)僅使用位置傳感器一個(gè)傳感器時(shí),除了轉(zhuǎn)速反饋,只有加速度適合作反饋量。以下將從收斂性和轉(zhuǎn)矩控制效果兩個(gè)方面分析基于加速度閉環(huán)控制方法的可行性。
基于加速度閉環(huán)控制方法的框圖如圖1所示。加速度為跟蹤變量,因此近似認(rèn)為
式中,為復(fù)頻率。因此,當(dāng)滿足所有極點(diǎn)在左半平面時(shí),該閉環(huán)系統(tǒng)穩(wěn)定,即滿足
圖1 基于加速度閉環(huán)控制方法的框圖
電機(jī)的機(jī)械運(yùn)動(dòng)方程為
式中,e()為電磁轉(zhuǎn)矩;L為負(fù)載轉(zhuǎn)矩;為轉(zhuǎn)動(dòng)慣量;為摩擦系數(shù)。
當(dāng)轉(zhuǎn)速趨于穩(wěn)定時(shí),即
其中
根據(jù)機(jī)械運(yùn)動(dòng)方程式(5)得到
根據(jù)式(7)可得
式中,1為常數(shù),該常數(shù)與給定轉(zhuǎn)速和負(fù)載轉(zhuǎn)矩相關(guān)。電磁轉(zhuǎn)矩和加速度近似呈線性關(guān)系。
假定在1時(shí)轉(zhuǎn)速趨于穩(wěn)定,根據(jù)式(2),有
式中,2為常數(shù),由轉(zhuǎn)速穩(wěn)定可知,2必然約等于零。因此根據(jù)式(12),有
因此,當(dāng)加速度脈動(dòng)小時(shí),轉(zhuǎn)矩脈動(dòng)必然是小的。
不對(duì)稱半橋功率變換器是開(kāi)關(guān)磁阻電機(jī)最常用的功率變換器,其結(jié)構(gòu)如圖2所示。每相有四種開(kāi)關(guān)狀態(tài),以A相為例,如圖3所示,分別是(1=1,2=1),(1=0,2=1),(1=1,2=0),(1=0,2=0),其中,1代表開(kāi)通,0代表關(guān)斷。這四種開(kāi)關(guān)狀態(tài)對(duì)應(yīng)三種繞組電壓。不計(jì)晶體管導(dǎo)通壓降和導(dǎo)線壓降,(1=1,2=1)對(duì)應(yīng)dc,(1=0,2=1)和(1=1,2=0)對(duì)應(yīng)0,(1=0,2=0)對(duì)應(yīng)-dc。dc為母線電壓。在電感值上升區(qū),根據(jù)開(kāi)關(guān)磁阻電機(jī)電路方程有
圖3 不對(duì)稱半橋功率變換器的四種開(kāi)關(guān)狀態(tài)
因此,在電感上升區(qū)域,電磁轉(zhuǎn)矩隨著電流上升而上升,隨著電流下降而下降。由式(10)可知,加速度隨電磁轉(zhuǎn)矩上升而上升,隨電磁轉(zhuǎn)矩下降而下降。綜上所述,當(dāng)(1=1,2=1)時(shí),加速度上升,當(dāng)(1=0,2=1),(1=1,2=0),(1=0,2=0)時(shí),加速度下降,(1=0,2=0)的加速度下降速率大于(1=0,2=1)和(1=1,2=0)的加速度下降速率。
圖4 傳統(tǒng)滯環(huán)控制的仿真結(jié)果
圖5 電機(jī)磁鏈曲線
圖6 增加一個(gè)滯環(huán)上限的滯環(huán)控制的仿真結(jié)果
圖7 關(guān)斷角為19°時(shí)的仿真結(jié)果
本文的實(shí)驗(yàn)平臺(tái)如圖8所示。實(shí)驗(yàn)電機(jī)采用12/8開(kāi)關(guān)磁阻電機(jī),其主要參數(shù)列在表1中。位置信號(hào)通過(guò)光電編碼器E6B2-CWZ6C測(cè)得。對(duì)比實(shí)驗(yàn)中的電流信號(hào)通過(guò)電流傳感器LT108-S7測(cè)得。位置信號(hào)和電流信號(hào)輸入控制芯片DSP TMS320F28335,在DSP內(nèi)計(jì)算速度、加速度以及執(zhí)行控制方法,得到門(mén)極驅(qū)動(dòng)信號(hào)。功率晶體管采用MOSFET,型號(hào)為IPP052N08N5。數(shù)模轉(zhuǎn)換過(guò)程和模數(shù)轉(zhuǎn)換過(guò)程分別由芯片AD5344和AD7606完成。電機(jī)的負(fù)載轉(zhuǎn)矩由磁粉制動(dòng)器提供。電磁轉(zhuǎn)矩通過(guò)查--表得到。
圖8 實(shí)驗(yàn)平臺(tái)
表1 開(kāi)關(guān)磁阻電機(jī)樣機(jī)參數(shù)
由于本文方法的反饋量均直接或間接來(lái)自位置量,因此對(duì)位置量測(cè)量及速度計(jì)算方法進(jìn)行簡(jiǎn)要的誤差分析。對(duì)于光電編碼器E6B2-CWZ6C,兩個(gè)位置信號(hào)脈沖邊沿間隔0.09°,因此位置量測(cè)量的最大誤差為0.09°。測(cè)速采用的是測(cè)周法,其原理是以位置信號(hào)脈沖邊沿間隔除以通過(guò)這段間隔所花時(shí)間。對(duì)于DSP,時(shí)間計(jì)量方式為時(shí)鐘脈沖數(shù)乘以時(shí)鐘周期。這種測(cè)速法的誤差與光電編碼器精度無(wú)關(guān),取決于控制芯片的時(shí)鐘頻率,計(jì)時(shí)器最大誤差為一個(gè)時(shí)鐘周期。DSP28335的時(shí)鐘頻率為150MHz,如果QEP模塊的時(shí)基不分頻,那么時(shí)間計(jì)量的最大誤差為6.67ns。以給定轉(zhuǎn)速600r/min為例,轉(zhuǎn)過(guò)0.09°需要25ms,一個(gè)位置間隔的時(shí)間計(jì)量的最大誤差約為0.027%,因此速度計(jì)算誤差極小。
APC和VPWM是兩種常用的不需要電流傳感器的開(kāi)關(guān)磁阻電機(jī)控制方法,VPWM的轉(zhuǎn)矩控制效果優(yōu)于APC。因此,將VPWM作為本文控制方法的一個(gè)參照,在同樣硬件條件下,驗(yàn)證本文控制方法在控制效果上的改進(jìn)。DTC是目前轉(zhuǎn)矩控制效果較好的控制方式。以DTC為參照,觀察本文控制方法及其在控制效果上的差異。該DTC采用與本文相同的滯環(huán)方式實(shí)現(xiàn)。根據(jù)第2.3節(jié)的分析,開(kāi)通角和關(guān)斷角分別設(shè)為0°和20°。在低速輕載、高速重載、變轉(zhuǎn)速和變負(fù)載條件下,分別采用VPWM、DTC和本文控制方法控制電機(jī),觀察并對(duì)比控制效果。轉(zhuǎn)矩脈動(dòng)ripple定義為:ripple=max-min,max和min分別為最大電磁轉(zhuǎn)矩和最小電磁轉(zhuǎn)矩。
母線電壓設(shè)為12V。DTC的滯環(huán)下限為-0.01N·m,兩個(gè)滯環(huán)上限分別為0.01N·m和0.02N·m。本文控制方法的滯環(huán)下限為-5rad/s2,兩個(gè)滯環(huán)上限分別為5rad/s2和10rad/s2。當(dāng)轉(zhuǎn)速穩(wěn)定時(shí),取兩個(gè)周期的波形,實(shí)驗(yàn)結(jié)果如圖9所示。在該運(yùn)行條件下,VPWM的max約為0.4N·m,min約為0.08N·m,ripple約為0.32N·m;DTC和本文控制方法的max約為0.32N·m,min約為0.12N·m,ripple約為0.2N·m。
圖9 低速輕載時(shí)的實(shí)驗(yàn)結(jié)果
母線電壓設(shè)為36V。DTC的滯環(huán)下限為-0.03N·m,兩個(gè)滯環(huán)上限分別為0.03N·m和0.06N·m。本文控制方法的滯環(huán)下限為-15rad/s2,兩個(gè)滯環(huán)上限分別為15rad/s2、30rad/s2。當(dāng)轉(zhuǎn)速穩(wěn)定時(shí),取兩個(gè)周期的波形,實(shí)驗(yàn)結(jié)果如圖10所示。在該工作條件下,VPWM的max約為1.8N·m,min約為0.2N·m,ripple約為1.6N·m;DTC和本文控制方法的max約為1N·m,min約為0.5N·m,ripple約為0.5N·m。
圖10 高速重載時(shí)的實(shí)驗(yàn)結(jié)果
母線電壓設(shè)為24V。起始狀態(tài)設(shè)為(600r/min, 0.2N·m)。變轉(zhuǎn)速時(shí)的實(shí)驗(yàn)結(jié)果如圖11所示。在變轉(zhuǎn)速過(guò)程中,VPWM的max接近4N·m;DTC和本文控制方法的max約為3N·m。
圖11 變轉(zhuǎn)速時(shí)的實(shí)驗(yàn)結(jié)果
母線電壓設(shè)為24V。起始狀態(tài)為(600r/min, 0.2N·m)。變負(fù)載時(shí)的實(shí)驗(yàn)結(jié)果如圖12所示。在變負(fù)載過(guò)程中,VPWM的一個(gè)周期的ripple最大約為2N·m;DTC和本文控制方法的一個(gè)周期的ripple最大約為0.5N·m。
由以上電機(jī)的動(dòng)態(tài)過(guò)程和穩(wěn)態(tài)過(guò)程的實(shí)驗(yàn)結(jié)果可知:和VPWM相比,在轉(zhuǎn)矩控制效果上,本文控制方法具有顯著優(yōu)勢(shì);和DTC相比,對(duì)于電流波形、電磁轉(zhuǎn)矩波形和轉(zhuǎn)速波形,本文方法均與其相似。該結(jié)果證明了加速度控制和轉(zhuǎn)矩控制的等效性,與第2節(jié)的理論分析相一致。
圖12 變負(fù)載時(shí)的實(shí)驗(yàn)結(jié)果
本文提出了一種開(kāi)關(guān)磁阻電機(jī)無(wú)電流傳感器控制方法。電流傳感器的省去提高了系統(tǒng)可靠性并降低了系統(tǒng)的成本。在缺少電流信息的情況下,該方法對(duì)位置信息進(jìn)行了充分利用,將傳統(tǒng)控制方法中不常使用的位置量二階導(dǎo)數(shù)——加速度作為反饋量,取得了良好的控制效果。從理論上證明了該方法對(duì)轉(zhuǎn)矩的間接控制能力。采用滯環(huán)方法跟蹤參考加速度,根據(jù)開(kāi)關(guān)磁阻電機(jī)的磁鏈特征,增加了一個(gè)滯環(huán)上界,減小了轉(zhuǎn)矩脈動(dòng)。根據(jù)實(shí)驗(yàn)結(jié)果,本文方法的控制性能優(yōu)于現(xiàn)有的不依賴電流傳感器的控制方法,與DTC相當(dāng)。除此之外,與DTC相比,本文控制方法的優(yōu)勢(shì)還在于不需要進(jìn)行電流-電磁轉(zhuǎn)矩?fù)Q算,減少了在線計(jì)算時(shí)間,并且不受電機(jī)參數(shù)限制,魯棒性更好。旋轉(zhuǎn)電機(jī)的機(jī)械運(yùn)動(dòng)方程相同,因此本文的控制方法能為其他類型旋轉(zhuǎn)電機(jī)的控制提供參考。
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Current Sensorless Control Method of Switched Reluctance Motors
1,2,31,2,3456
(1. School of Electrical Engineering China University of Mining and Technology Xuzhou 221116 China 2. International Joint Research Center of Central and Eastern European Countries on New Energy Electric Vehicle Technology and Equipment Xuzhou 221008 China 3. International Cooperation Joint Laboratory of New Energy Power Generation and Electric Vehicles of Jiangsu Province Colleges and Universities Xuzhou 221008 China 4. Faculty of Control Systems and Robotics Engineer Saint-Petersburg National Research University of Information Technologies Mechanics and Optics St. Petersburg 197101 Russia 5. Electric Drives Department Moscow Power Engineering Institute National Research University Moscow 111250 Russia 6. Department of Automation of Mining Production University of Mining and Geology "St. Ivan Rilski" Sofia 1700 Bulgaria)
Control variables are usually measured by sensors. However, sensors can increase system costs, cause interference, and reduce reliability. Thus, the sensorless technique is widely studied. For switch reluctance motor (SRM) systems, according to present control methods, current information is necessary to torque control. A new control variable is toned to replace the current and have a simple relation with electromagnetic torque to achieve good control performance without current sensors. Rotor position and speed are necessary for any SRM control methods, usually measured by a position sensor. The first derivative of position is speed, the second derivative of position is acceleration, and the third and more derivatives of position have no physical meaning. When only a position sensor is used in the SRM system, besides the speed, the acceleration is the unique possible feedback variable. Therefore, a current sensorless control method of SRMs using double closed loops of speed and acceleration is proposed.
Firstly, the feasibility of the proposed method is analyzed in two points. ① Its convergence is proven; ② The approximate linear relation between electromagnetic torque and acceleration in a steady state is proven, and the equivalence of torque control and acceleration control is analyzed further. Subsequently, a hysteresis control method with three bounds is proposed to track reference acceleration. According to flux features of the SRM, there is a position where inductance increase sharply, and if the phase current cannot be reduced timely, the electromagnetic torque will also increase sharply, leading to a large torque ripple. Thus, an extra upper bound is set, and a negative voltage is used to quickly reduce the phase current when the acceleration is beyond the upper bound. Finally, Given both motor efficiency and torque ripple, turn-on and turn-off angle are appropriately selected.
Angle position control (APC) and voltage pulse width modulation (VPWM) are two existing current sensorless control methods of SRMs. VPWM has better control performance than APC. Therefore, taking VPWM as a comparison object, the improvement of the proposed method is verified by experiments. The direct torque control (DTC) method is another comparison object to demonstrate the equivalence of torque control and acceleration control. The experiments are carried out under four conditions: low speed and light load, high speed and heavy load, speed change, and load change. Under (600r/min, 0.2N·m), the torque ripple of VPMM is about 0.32N·m, and those of DTC and the proposed method are about 0.2N·m. Under (1 500r/min, 0.7N·m), the torque ripple of VPMM is about 1.6N·m, and those of DTC and the proposed method are about 0.5N·m. If the initial condition is set to (600r/min, 0.2N·m), during speed change, the max torque of VPMM is about 4N·m, and those of DTC and the proposed method are about 0.2N·m. If the initial condition is set to (600r/min, 0.2N·m), during load change, the torque ripple of VPMM is about 2N·m, and those of DTC and the proposed method are about 0.5N·m.
The experimental results show that the proposed method is comparable to the DTC and better than the VPWM in control performance. In addition, the relationship between the current and the electromagnetic torque is complex and nonlinear, but the conversion between them is needed in DTC. Due to the approximately linear relationship between electromagnetic torque and acceleration, the proposed method is independent of the electromagnetic torque, thus having a lower computational cost.
Switched reluctance motor, current sensorless control method, acceleration, electromagnetic torque
TM301
10.19595/j.cnki.1000-6753.tces.212148
國(guó)家自然科學(xué)基金國(guó)際(地區(qū))合作與交流項(xiàng)目、2019年度國(guó)家自然科學(xué)基金委員會(huì)與埃及科學(xué)研究技術(shù)院合作研究項(xiàng)目(51961145401)和徐州市推動(dòng)科技創(chuàng)新專項(xiàng)資金項(xiàng)目-創(chuàng)新能力建設(shè)計(jì)劃(KC21315)資助。
2021-12-30
2022-02-21
方成輝 男,1988年生,博士,研究方向?yàn)殚_(kāi)關(guān)磁阻電機(jī)系統(tǒng)及其控制。
E-mail: shenweiqianchong@126.com
陳 昊 男,1969年生,教授,博士生導(dǎo)師,研究方向?yàn)殚_(kāi)關(guān)磁阻電機(jī)系統(tǒng)及其控制。
E-mail: hchen@cumt.edu.cn(通信作者)
(編輯 崔文靜)