【作者】 白皓然；

【导师】 王凤翔；

【作者基本信息】 沈阳工业大学 ， 电力电子与电力传动， 2009， 博士

【摘要】 高速电机具有体积小、功率密度大和效率高等优点,但同时具有单位体积损耗大和散热困难等不足,尤其是其功率变换装置产生的谐波电流会增加高速电机的损耗和温升。如何减小谐波成为高速电机功率变换系统的重要研究课题。本文研究内容是国家自然科学基金重点资助项目“微型燃气轮机—高速发电机分布式发电与能量转换系统研究”(编号50437010)的部分研究内容,集中研究高速发电机功率变换系统的谐波抑制技术,主要包括以下内容:(1)为了抑制高速发电机输出AC/DC功率变换装置的电流谐波,并考虑高速发电机自启动的需求,研究了具有谐波抑制功能的PWM整流器/逆变器。建立了小信号分析数学模型,推导了传递函数;针对功率器件开关频率受到限制的问题,采用了特定谐波消除脉宽调制(SHEPWM)策略;分析了单极性和双极性脉冲控制模型下开关角的求解方法;通过线电压过零检测确定电网电压相位及电压和电流双闭环控制,实现了稳态下电流的无静差调节,并对以上控制策略进行了仿真和实验研究。(2)为了克服PWM整流器高频下功率器件开关频率的限制与控制技术复杂的问题,提出了一种采用移相电抗器的多相整流电路抑制网侧谐波电流的方法,通过选择移相角度可消除或抑制特定次数的网侧谐波电流。分析了移相电抗器的结构、绕组连接方式和谐波抑制原理,建立了移相电抗器整流系统的数学模型,进行了六相和十二相移相电抗器整流系统的仿真和实验研究。实验结果表明移相电抗器应用于高频整流可有效地抑制网侧电流谐波。(3)为了满足高速发电机自启动和谐波抑制的需要,研究了具有逆变器和有源滤波器双重功能的变流器,在高速发电机启动时用作PWM逆变器,当高速发电机正常运行时用作有源滤波器。分析了有源滤波器和补偿对象容量之间的关系,研究了有源滤波器谐波电流的检测方法、采用直流母线电压外环和谐波电流内环的控制策略以及特定谐波消除的控制方法,并对频率1000Hz不同调制策略的谐波抑制效果进行了对比分析。(4)针对高频谐波抑制引入了3次谐波无源注入和单开关PWM整流器6次谐波注入两种谐波电流注入方法。分析了两种方法抑制网侧输入电流谐波的基本原理,研究了具体控制策略,并分别进行了频率1000Hz仿真实验研究。(5)为了满足分布式发电系统不同供电用户的需求,研究了具有承受不平衡负载功能的三相四桥臂逆变器。推导了三相四桥臂逆变器的传递函数,建立了系统传递函数矩阵;分析了三维空间电压矢量调制策略,给出了三棱柱判断、四面体的区分、各个空间矢量作用时间的计算方法,并进行了仿真和实验研究。仿真和实验结果表明,三相四桥臂逆变器在不平衡负载下能保证输出电压的对称关系。(6)研制了用于额定功率75kW额定转速60000r/min高速永磁发电机输出AC/DC功率变换的六相移相电抗器,并进行了实验研究。设计了基于TMS320LF2407A双DSP的实验平台,完成了PWM双向变流器和三相四桥臂逆变器的部分实验。更多还原

【Abstract】 The main advantages of the high speed machine are small size and high power density. However, the high speed machine suffers from higher loss density and cooling difficulty due to small cooling area, especially the high frequency harmonic currents produced by the power conversion system increase the loss and temperature of high speed machine. How to reduce the harmonic components is an important problem to be solved for the power conversion system design. The study of this thesis is a part of the project-"The study on distributed high speed generator system driven by micro-turbines and its energy conversion system", which is funded by the National Natural Science Foundation of China (No. 50437010). The study of the thesis is concentrated to the harmonics repression technology for high speed generator power conversion system. The main contents are listed as follows:(1) To reduce the current harmonics produced by the AC/DC power conversion and meet the requirements on self-starting, a PWM rectifier/inverter with current harmonics repression function is investigated. The mathematical model of small-signal is established. A special harmonic elimination pulse-width modulation (SHEPWM) strategy is utilized to overcome maximum switching frequency limit. The methods to solve switching angles are analyzed in the unipolar mode and bipolar mode respectively. Space voltage vector phase angle is determined by testing the zero crossing of line voltage, the no-error of current in the stable state is obtained through double closed loop. The simulation and experimental studies based on the above control strategies are carried out.(2) To overcome the maximum switching frequency limit and avoid complicated control scheme of PWM rectifier, a new kind of multi-phase rectifying alternating circuit using phase shifting reactor for harmonics elimination is proposed. The selected harmonic components can be reduced or eliminated by selecting correspondent phase-shifting angles. The harmonics repression principle, structrure of phase-shifting reactor, determination of turns and connection mode of the phase-shifting windings etc. are analyzed. The mathematical model of multi-phase rectifying system with phase shifting reactors are built. The simulation and experimental study on a 6-phase and 12-phase rectifying system with phase shifting reactor are carried out. The experimental results show that the multi-phase rectifying system with phase shifting reactor can effectively reduce the current harmonics on the AC power supply side.(3) To meet the requirements of harmonic suppression and self-starting of the high speed generator, a combined converter of inverter with active power filter (APF) is investigated. The APF/inverter works as an inverter during the generator starting and as an APF during the normal AC/DC power conversion. The relation between the capacity of APF and that of the compensation objects is analyzed. The detection method on harmonic current, the control strategy of double closed loop and the special harmonic elimination control technology are studied. The comparative study on harmonic suppression at frequency 1000Hz for different modulation strategies is carried out.(4) Two approaches, a third-order harmonic injection with passive circuit and a sixth-order harmonic injection of a single-switch PWM rectifier, are employed to suppress the dominant harmonic components in the input currents on distributed high speed generator system. Based on their principle analysis, the relevant strategies are investigated and the simulation studies at 1000 Hz are carried out respectively.(5) To satisfy the requirement of different users, a three-phase four-leg circuit topology inverter is investigated to balance output voltage. The transfer functions and system transfer functions matrix are deduced. Three-dimensional space voltage vector modulation strategy is analyzed. The triangular prism judgment, the tetrahedron discrimination and computational methods of space vector action time are discussed. The simulation results verify the feasibility of the proposed design structure and control strategy.(6) A six-phase-shift reactor prototype is developed and tested, which is used for the AC/DC power conversion in the high speed permanent-magnet generator with rated power of 75kW and rated speed of 60000r/min. In addition, an experimental platform is also designed and built based on dual DSP (TMS320LF2407A), the bidirectional PWM converter and 3-phase 4-leg inverter are tested partly based on the platform.更多还原