張懿 吳嘉欣 孫霄陽 韋漢培 魏海峰 李垣江 儲(chǔ)建華
摘要:針對(duì)傳統(tǒng)滑模觀測器低速性能差的問題,提出一種帶定子電阻辨識(shí)的五相感應(yīng)電機(jī)滑模速度觀測器,實(shí)現(xiàn)寬范圍的五相感應(yīng)電機(jī)無速度傳感器運(yùn)行。建立五相感應(yīng)電機(jī)在旋轉(zhuǎn)坐標(biāo)系下的電壓方程,基于此將五相感應(yīng)電機(jī)解耦成基波平面與三次諧波平面分別獨(dú)立控制。諧波面上構(gòu)建第一滑模觀測器用于電機(jī)定子電阻和轉(zhuǎn)子轉(zhuǎn)速在線辨識(shí)。在此基礎(chǔ)上,將第一滑模觀測器辨識(shí)結(jié)果加載入基波面上的第二滑模觀測器,用于轉(zhuǎn)子電阻和轉(zhuǎn)子時(shí)間常數(shù)在線觀測,繼而有效克服溫度、集膚效應(yīng)等因素對(duì)轉(zhuǎn)子參數(shù)的影響,進(jìn)一步提高無速度傳感器運(yùn)行性能。實(shí)驗(yàn)結(jié)果驗(yàn)證了本文所設(shè)計(jì)雙滑模觀測器無速度傳感器技術(shù)的有效性和實(shí)用性。
關(guān)鍵詞:五相感應(yīng)電機(jī);滑模觀測器;定子電阻辨識(shí);解耦控制;無速度傳感器
DOI:10.15938/j.emc.(編輯填寫)
中圖分類號(hào):(TM301) ? 文獻(xiàn)標(biāo)志碼:A ? ? ? ? ?文章編號(hào):1007 -449X(2017)00-0000-00(編輯填寫)
Abstract:The performance of the traditional sliding mode observer at low speed is poor. In view of this problem, a sliding mode speed observer for five phase induction motor with stator resistance identification is proposed to realize the wide range speed sensorless operation. The voltage equation of the motor inrotating coordinate system was established. Based on this, the motor was decoupled from the fundamental plane and the three harmonic plane independently. On the harmonic plane, first observer was constructed to realize the online identification of stator resistance and rotor speed. And on the fundamental plane, identification results of the first observer were loaded on the second observer to realize the online observation of rotor resistance and time constant, then the effect of temperature and skin effect on the rotor parameters were effectively overcome to further improve the performance of the speed sensorless. Experimental results verified the effectiveness and practicability of speed sensorless technology with double sliding mode observer designed in this paper.
Keywords: five phase induction motor; sliding mode observer;stator resistance identification; decoupling control; speed sensorless
0 引言
多相感應(yīng)電機(jī)閉環(huán)控制需速度傳感器,考慮到減小控制裝置大小、降低成本,以及系統(tǒng)的后期維護(hù)和可靠性問題,需摒棄傳感器,實(shí)現(xiàn)無速度傳感器控制。傳統(tǒng)無傳感器控制算法大多基于滑模觀測器擴(kuò)展反電勢的觀測,但因其固有抖振特性以及測量噪聲使得其輸出反電勢存在大量的噪聲擾動(dòng),尤其在低轉(zhuǎn)速工況下反電勢幅值低,性噪比低,造成電機(jī)轉(zhuǎn)速值估計(jì)不準(zhǔn)確。另外,多相感應(yīng)電機(jī)高性能控制中,電機(jī)參數(shù)對(duì)解耦效果以及控制精度至關(guān)重要。隨著運(yùn)行工況的變化,集膚效應(yīng)和溫升等會(huì)造成定、轉(zhuǎn)子阻值參數(shù)值發(fā)生攝動(dòng),氣隙磁場飽和度也會(huì)相應(yīng)地影響電感參數(shù)值,造成轉(zhuǎn)子時(shí)間常數(shù)等的波動(dòng),影響整個(gè)控制效果[1 - 3]。因此,對(duì)于多相感應(yīng)電機(jī)來說,相關(guān)定、轉(zhuǎn)子參數(shù)的準(zhǔn)確辨識(shí)有著至關(guān)重要的意義。
為有效降低電機(jī)參數(shù)攝動(dòng)對(duì)控制性能的影響,國內(nèi)外學(xué)者對(duì)有關(guān)電機(jī)參數(shù)辨識(shí)問題進(jìn)行了不懈努力,各種參數(shù)辨識(shí)法被相繼提出,如模型參考自適應(yīng)法[4 - 5]、人工智能法[6 - 8](遺傳算法、模糊系統(tǒng)、神經(jīng)網(wǎng)絡(luò)等)、遞推最小二乘法[9]以及擴(kuò)展Kalman濾波法[10 - 12]等。感應(yīng)電機(jī)參數(shù)辨識(shí)方面,其中以轉(zhuǎn)子時(shí)間常數(shù)辨識(shí)較為困難,其作為間接磁場定向控制的敏感變量。Zhao L等在文獻(xiàn)[13]中通過轉(zhuǎn)子槽諧波提取技術(shù)估計(jì)電機(jī)轉(zhuǎn)速,在轉(zhuǎn)速估計(jì)的前提下,提出一種用于轉(zhuǎn)子時(shí)間常數(shù)辨識(shí)的感應(yīng)電機(jī)模型導(dǎo)數(shù)形式,克服了轉(zhuǎn)子磁鏈計(jì)算中的純積分問題,調(diào)整后的粒子群優(yōu)化算法利用該模型跟蹤轉(zhuǎn)子時(shí)間常數(shù)。Laroche E等在正弦穩(wěn)態(tài)模式下進(jìn)行感應(yīng)電機(jī)參數(shù)估計(jì),基于參數(shù)攝動(dòng)得到一個(gè)模型,相對(duì)于新的參數(shù)集是線性的,此方法可在較小計(jì)算量的情況下得到一系列的參數(shù)估計(jì),避免了關(guān)注局部極小問題[14]。Yepes A G等人在文獻(xiàn)[15]中采用最小二乘法,實(shí)現(xiàn)了多相感應(yīng)電機(jī)相關(guān)參數(shù)的離線辨識(shí),并在文獻(xiàn)[16]中對(duì)漏感等參數(shù)進(jìn)行在線辨識(shí),但是該方法只局限于正弦波結(jié)構(gòu)的多相電機(jī)??傮w看來,目前多相感應(yīng)電機(jī)在抗參數(shù)攝動(dòng)方面仍存在諸多難點(diǎn),相關(guān)研究有待進(jìn)一步加強(qiáng)。
針對(duì)復(fù)雜工況下五相感應(yīng)電機(jī)定、轉(zhuǎn)子參數(shù)攝動(dòng)以及傳統(tǒng)滑模觀測器無速度傳感器低速性能差的問題,設(shè)計(jì)一種雙滑模觀測器用于電機(jī)相關(guān)參數(shù)的在線辨識(shí)。提出以下思路:(1)將五相感應(yīng)電機(jī)基波面和諧波面進(jìn)行解耦,獨(dú)立控制,雙平面內(nèi)分別構(gòu)建滑模觀測器;(2)諧波面觀測器實(shí)現(xiàn)定子電阻和轉(zhuǎn)速的在線辨識(shí),加載于基波面滑模狀態(tài)方程的構(gòu)建,有效提高低速運(yùn)行效果;(3)基波面觀測器實(shí)現(xiàn)轉(zhuǎn)子電阻和轉(zhuǎn)子時(shí)間常數(shù)的在線觀測,降低不同轉(zhuǎn)差對(duì)其的影響,提高瞬態(tài)響應(yīng)性能。為驗(yàn)證本文所提出控制策略的可行性和實(shí)用性,選取1.2kW五相感應(yīng)電機(jī)為實(shí)驗(yàn)控制對(duì)象,對(duì)比實(shí)驗(yàn)結(jié)果驗(yàn)證了設(shè)計(jì)觀測器參數(shù)辨識(shí)的可行性。
3 實(shí)驗(yàn)驗(yàn)證與分析
在五相感應(yīng)電機(jī)交流調(diào)速平臺(tái)上,對(duì)本文提出的雙滑模觀測器進(jìn)行實(shí)驗(yàn)研究,實(shí)驗(yàn)電機(jī)參數(shù)為:額定功率 ,額定電壓 ,額定電流 ,極對(duì)數(shù) ,定子電阻 ,基波轉(zhuǎn)子電阻 ,諧波轉(zhuǎn)子電阻 ,基波互感 ,諧波互感 ,輸出額定轉(zhuǎn)矩 ,額定頻率 ,額定轉(zhuǎn)速 。實(shí)驗(yàn)中滑模面比例系數(shù) ,轉(zhuǎn)速自適應(yīng)系數(shù) ,定子電阻自適應(yīng)系數(shù) 。具體實(shí)驗(yàn)系統(tǒng)平臺(tái)如圖2所示。
(1)諧波平面的滑模觀測器驗(yàn)證
為驗(yàn)證定子電阻辨識(shí)對(duì)于滑模觀測器的有效性,分別基于傳統(tǒng)滑模觀測器和本文提出的帶定子電阻辨識(shí)的滑模觀測器作對(duì)比實(shí)驗(yàn),如圖3和圖4所示。分別給定電機(jī) 的低轉(zhuǎn)速值,圖3滑模觀測算法中始終將定子電阻值設(shè)置為 不變,對(duì)比圖3,圖4中滑模觀測算法中的定子電阻值始終在辨識(shí)更新中,定子電阻初始值為 。對(duì)比結(jié)果可知,定子電阻值誤差對(duì)于諧波面上的轉(zhuǎn)子磁鏈、定子電流觀測以及轉(zhuǎn)速估計(jì)均產(chǎn)生影響,產(chǎn)生相應(yīng)的諧波和抖動(dòng),尤其在轉(zhuǎn)子轉(zhuǎn)速估計(jì)方面,定子電阻誤差使得轉(zhuǎn)子估計(jì)誤差大大增加,抖振尤為明顯。
圖4投入定子電阻辨識(shí)環(huán)節(jié),定子電阻辨識(shí)值從設(shè)定初值迅速收斂至實(shí)際值,轉(zhuǎn)速估計(jì)逼近實(shí)際轉(zhuǎn)速,誤差大大減小,抖振消失,諧波面上的轉(zhuǎn)子磁鏈以及定子電流觀測更加平滑,正弦度增強(qiáng)。經(jīng)分析,電機(jī)低速運(yùn)行時(shí),反電勢值較小,定子電阻壓降對(duì)系統(tǒng)影響較大,定子電阻的辨識(shí)對(duì)于低轉(zhuǎn)速估計(jì)尤為重要。
(2)基波平面的滑模觀測器驗(yàn)證
圖5為空載工況下基波面轉(zhuǎn)子電阻和轉(zhuǎn)子時(shí)間常數(shù)辨識(shí)結(jié)果,考慮到滑模固有抖振性,將轉(zhuǎn)子電阻和轉(zhuǎn)子常數(shù)自適應(yīng)律系數(shù)作相應(yīng)減小, 左右收斂至實(shí)際值。對(duì)比圖6滿載工況下的實(shí)驗(yàn)結(jié)果,滿載工況下轉(zhuǎn)子電阻辨識(shí)值由空載的 變?yōu)榧s ,增大約 ,轉(zhuǎn)子時(shí)間常數(shù)相應(yīng)地減小,由空載的 降低至 。經(jīng)分析,一方面負(fù)載的變化改變了轉(zhuǎn)差率,導(dǎo)致轉(zhuǎn)子電流頻率隨之改變,由于集膚效應(yīng)的存在改變了轉(zhuǎn)子等效電阻值,并對(duì)轉(zhuǎn)子漏感造成影響;另一方面,給定負(fù)載的變化增大了電流幅值,電機(jī)內(nèi)溫升使得轉(zhuǎn)子電阻增大。
為了驗(yàn)證電機(jī)運(yùn)行動(dòng)態(tài)過程中參數(shù)辨識(shí)算法的有效性,進(jìn)行了負(fù)載突變下的基波面轉(zhuǎn)子電阻和轉(zhuǎn)子時(shí)間常數(shù)辨識(shí)實(shí)驗(yàn),如圖7所示。在4s時(shí)刻之前,電機(jī)運(yùn)行在空載工況下,對(duì)應(yīng)圖5所示的運(yùn)行工況,在4s時(shí)刻給定電機(jī)突加額定負(fù)載,由圖可知,轉(zhuǎn)子電阻辨識(shí)經(jīng)過大約0.4s時(shí)間快速趨于穩(wěn)態(tài),幾乎無超調(diào),而轉(zhuǎn)子時(shí)間常數(shù)辨識(shí)值在突加負(fù)載時(shí)會(huì)有一個(gè)較小的超調(diào),之后經(jīng)過大約0.7s時(shí)間同樣趨于穩(wěn)態(tài),最終辨識(shí)結(jié)果與圖6基本一致。
為了驗(yàn)證電機(jī)運(yùn)行動(dòng)態(tài)過程中轉(zhuǎn)速辨識(shí)算法的有效性,進(jìn)行了給定轉(zhuǎn)速突變下的轉(zhuǎn)速辨識(shí)實(shí)驗(yàn),如圖8所示為估計(jì)轉(zhuǎn)速與實(shí)際轉(zhuǎn)速對(duì)比。在3.0s時(shí)刻之前,給定電機(jī)200r/min的轉(zhuǎn)速運(yùn)行,在3.0s時(shí)刻,給定轉(zhuǎn)速突升為額定轉(zhuǎn)速值,在9.0s時(shí)刻,給定轉(zhuǎn)速突降為200r/min。由圖可知,電機(jī)轉(zhuǎn)速估計(jì)在給定轉(zhuǎn)速突變時(shí)能夠嚴(yán)格跟隨實(shí)際值,估計(jì)動(dòng)態(tài)性能較好。
4 結(jié)論
傳統(tǒng)三相感應(yīng)電機(jī)控制的基礎(chǔ)上,將五相感應(yīng)電機(jī)解耦成雙平面的三相感應(yīng)電機(jī),實(shí)現(xiàn)五相感應(yīng)電機(jī)雙平面多參數(shù)并行辨識(shí)。諧波面構(gòu)建帶定子電阻辨識(shí)的轉(zhuǎn)速滑模觀測器,有效拓寬了無速度傳感器運(yùn)行范圍,改善低速運(yùn)行效果。在諧波面定子電阻和轉(zhuǎn)速辨識(shí)的基礎(chǔ)上構(gòu)建基波面上的新型滑模觀測器,實(shí)現(xiàn)了基波面上的轉(zhuǎn)子參數(shù)在線觀測,有效避免溫升、集膚效應(yīng)對(duì)轉(zhuǎn)子參數(shù)的攝動(dòng)影響。實(shí)驗(yàn)結(jié)果顯示所設(shè)計(jì)的滑模觀測器觀測效果較好,具有廣闊的應(yīng)用前景。
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