背靠背三電平PWM變換器矢量控制系統(tǒng)研究
發(fā)布時間：2018-09-11 16:02
【摘要】：本文針對交流異步電機驅(qū)動,對背靠背三電平脈沖寬度調(diào)制(Pulse Width Modulation, PWM)變換器矢量控制系統(tǒng)進行研究。 對三種常用的快速SVPWM算法進行分析與比較,在此基礎上提出了一種計算量小、易于數(shù)字實現(xiàn)的任意多電平SVPWM通用算法。并將所提的通用SVPWM算法在現(xiàn)場可編程門陣列(Field Programmable Gate Array,FPGA)上設計實現(xiàn)。 針對單側二極管中點箝位型三電平PWM變換器,提出一種新的混合SVPWM的電容中點電位平衡控制算法。根據(jù)每個扇區(qū)不同的小矢量作用,并結合電容電壓偏差量及三相電流的極性來設置不同的小矢量作用時間調(diào)節(jié)因子,然后根據(jù)三相電流的變化情況使調(diào)制在常規(guī)的SVPWM和基于虛擬矢量的SVPWM之間進行切換,以實現(xiàn)對中點電位進行分扇區(qū)的精細控制。 針對背靠背的二極管中點箝位型三電平PWM變換器電容中點電壓平衡控制問題,提出一種基于雙側信號的中點電位平衡綜合預測控制算法。該算法對雙側的三相電流和直流側電容電壓進行采樣和預測,進而給出一個能夠表征電容中點電壓預期控制指標的品質(zhì)函數(shù)。通過遞推運算使品質(zhì)函數(shù)取最小值,從而獲得下一個調(diào)制周期最佳中點電壓控制的冗余矢量時間分配因子。 在已有的三電平PWM整流器DPC的基礎上,提出了在一個開關周期內(nèi)具有雙非零電壓矢量輸出的三電平PWM整流器DPC算法。該算法通過對下一時刻的有功和無功進行預測,每次選擇對有功和無功調(diào)節(jié)作用相反的兩個電壓矢量進行輸出,并通過一個分配因子對兩個電壓矢量的作用時間進行分配,從而實現(xiàn)了對功率的精細調(diào)整。 基于遞推最小二乘法,對三電平變頻器的電機參數(shù)靜態(tài)辨識進行建模和仿真,給出了中點電位不平衡與平衡的情況下,電機參數(shù)靜態(tài)辨識的仿真結果。提出一種交流異步電機電機參數(shù)動態(tài)在線辨識方法,通過在負載恒定時控制電機速度使其保持恒定來消除轉子磁鏈耦合項對參數(shù)動態(tài)在線辨識的影響,從而能夠利用遞推最小二乘法對電機參數(shù)進行在線計算,以達到電機參數(shù)動態(tài)在線辨識的實時性和高精確度要求。其中電機恒定速度的保持又是基于對轉子磁鏈和轉矩電流的恒定控制來實現(xiàn)。 提出了一種能夠使系統(tǒng)保持固定的開關頻率和采樣頻率且隨機效果不依賴于零矢量的三電平隨機SVPWM方法。通過隨機調(diào)整矢量在每個三角載波的上升段和下降段的時間分配來實現(xiàn)隨機SVPWM,并設計一種三重隨機化M序列來增強其隨機效果。該方法可使輸出的線電壓和相電流頻譜在較寬的頻帶范圍內(nèi)均勻分布,在整數(shù)倍開關頻率處的諧波幅值也大大降低。
[Abstract]:In this paper, the vector control system of back-to-back three-level pulse width modulation (PWM) converter driven by AC asynchronous motor is studied.
Based on the analysis and comparison of three commonly used fast SVPWM algorithms, a general algorithm for arbitrary multilevel SVPWM is proposed, which is easy to realize digitally with less computation. The proposed algorithm is designed and implemented on Field Programmable Gate Array (FPGA).
A novel neutral-point potential balance control algorithm for single-side diode neutral-point-clamped three-level PWM converter based on hybrid SVPWM is proposed. According to the different small vector action in each sector, different small vector action time adjustment factors are set according to the capacitor voltage deviation and the polarity of three-phase current. The variation of the current makes the modulation switch between the conventional SVPWM and the SVPWM based on the virtual vector to realize the fine sector control of the midpoint potential.
Aiming at the problem of neutral-point voltage balance control of capacitor in back-to-back diode neutral-point clamped three-level PWM converter, an integrated predictive control algorithm for neutral-point potential balance based on bilateral signals is proposed. The quality function of the voltage expectation control index is minimized by recursive operation, and the redundant vector time allocation factor of the best midpoint voltage control in the next modulation period is obtained.
Based on the existing DPC of three-level PWM rectifier, a DPC algorithm of three-level PWM rectifier with dual non-zero voltage vector output in one switching cycle is proposed. By predicting the active and reactive power at the next moment, the DPC algorithm selects two voltage vectors with opposite active and reactive power regulation at each time and passes through. A distribution factor is used to distribute the action time of the two voltage vectors, thus realizing fine power adjustment.
Based on the recursive least squares method, the static identification of motor parameters of three-level inverter is modeled and simulated. The simulation results of static identification of motor parameters under unbalanced and balanced neutral-point potentials are given. A dynamic on-line identification method of motor parameters of AC asynchronous motor is proposed. The motor speed is controlled by constant load. By keeping the rotor flux coupling constant, the influence of rotor flux coupling term on on-line parameter identification can be eliminated, and the motor parameters can be calculated on-line using the recursive least squares method to meet the real-time and high accuracy requirements of on-line parameter identification. The constant control of the torque current is achieved.
A three-level stochastic SVPWM method is proposed, in which the switching frequency and sampling frequency can be kept constant and the random effect does not depend on zero vectors. The stochastic SVPWM is realized by randomly adjusting the time allocation between the rising and falling phases of each triangular carrier. A triple randomized M sequence is designed to enhance the randomness of the system. This method can make the output line voltage and phase current spectrum distribute uniformly in a wide frequency band and greatly reduce the harmonic amplitude at integer multiple switching frequency.
【學位授予單位】：中南大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM46
本文編號：2237162
[Abstract]:In this paper, the vector control system of back-to-back three-level pulse width modulation (PWM) converter driven by AC asynchronous motor is studied.
Based on the analysis and comparison of three commonly used fast SVPWM algorithms, a general algorithm for arbitrary multilevel SVPWM is proposed, which is easy to realize digitally with less computation. The proposed algorithm is designed and implemented on Field Programmable Gate Array (FPGA).
A novel neutral-point potential balance control algorithm for single-side diode neutral-point-clamped three-level PWM converter based on hybrid SVPWM is proposed. According to the different small vector action in each sector, different small vector action time adjustment factors are set according to the capacitor voltage deviation and the polarity of three-phase current. The variation of the current makes the modulation switch between the conventional SVPWM and the SVPWM based on the virtual vector to realize the fine sector control of the midpoint potential.
Aiming at the problem of neutral-point voltage balance control of capacitor in back-to-back diode neutral-point clamped three-level PWM converter, an integrated predictive control algorithm for neutral-point potential balance based on bilateral signals is proposed. The quality function of the voltage expectation control index is minimized by recursive operation, and the redundant vector time allocation factor of the best midpoint voltage control in the next modulation period is obtained.
Based on the existing DPC of three-level PWM rectifier, a DPC algorithm of three-level PWM rectifier with dual non-zero voltage vector output in one switching cycle is proposed. By predicting the active and reactive power at the next moment, the DPC algorithm selects two voltage vectors with opposite active and reactive power regulation at each time and passes through. A distribution factor is used to distribute the action time of the two voltage vectors, thus realizing fine power adjustment.
Based on the recursive least squares method, the static identification of motor parameters of three-level inverter is modeled and simulated. The simulation results of static identification of motor parameters under unbalanced and balanced neutral-point potentials are given. A dynamic on-line identification method of motor parameters of AC asynchronous motor is proposed. The motor speed is controlled by constant load. By keeping the rotor flux coupling constant, the influence of rotor flux coupling term on on-line parameter identification can be eliminated, and the motor parameters can be calculated on-line using the recursive least squares method to meet the real-time and high accuracy requirements of on-line parameter identification. The constant control of the torque current is achieved.
A three-level stochastic SVPWM method is proposed, in which the switching frequency and sampling frequency can be kept constant and the random effect does not depend on zero vectors. The stochastic SVPWM is realized by randomly adjusting the time allocation between the rising and falling phases of each triangular carrier. A triple randomized M sequence is designed to enhance the randomness of the system. This method can make the output line voltage and phase current spectrum distribute uniformly in a wide frequency band and greatly reduce the harmonic amplitude at integer multiple switching frequency.
【學位授予單位】：中南大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM46
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，本文編號：2237162
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