消谐算法及在多电平逆变器中的应用

发布时间：2018-02-14 15:07

本文关键词： 特定谐波消除法非线性方程组同伦算法牛顿迭代法初值　出处：《北京交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着电力电子技术的快速发展,使得PWM逆变器广泛应用于各种交流调速系统,但逆变器输出中的谐波对电网及用电设备的危害愈来愈受到人们的重视,并且,高性能调速系统对逆变器效率与输出波形质量等的要求也越来越高,使得特定谐波消除PWM (SHEPWM)技术的研究成为交流调速领域的研究热点,特定谐波消除技术可实现谐波的选择性消除,控制输出波形的基波分量,本文针对该技术进行了相关研究。由于SHEPWM技术的数学模型是一组非线性方程组,本文首先针对该非线性方程组,推导了求解非线性方程组的牛顿迭代法和同伦算法的迭代公式,研究发现不同的初值对牛顿法迭代公式的收敛速度影响很大,而对同伦算法的收敛速度影响较小,但同伦算法的计算时间较长,总体收敛速度较慢,且迭代精度很低。然后,针对不同初值对利用牛顿迭代法求解非线性方程组的收敛速度影响很大的特点,对非线性方程组数值求解的初值给定作了进一步研究。利用经验公式法,三角载波比较法和重心重合法分别计算得到同等条件下的初值序列,并将计算的初值序列应用于牛顿迭代法对非线性方程组进行求解,求解结果显示：利用重心重合法计算得到的初值序列能更好地使迭代收敛。最后,基于MATLAB搭建二极管钳位型SPWM与SHEPWM三电平逆变器仿真模型,在SHEPWM消谐算法中利用重心重合法计算牛顿迭代公式的初值序列,并对非线性方程组进行求解,以求得的数值解作为SHEPWM的控制脉冲序列。仿真结果显示：SHEPWM方法控制下的输出波形中各次谐波的含量比SPWM方法控制下的输出谐波的含量低,即在相同的主电路、输入电压、开关频率、负载条件下,SHEPWM在谐波抑制方面优于SPWM。
[Abstract]:With the rapid development of power electronics technology, PWM inverters are widely used in various AC speed regulating systems. However, the harm of harmonics in inverter output to power grid and power equipment has been paid more and more attention. The requirement of inverter efficiency and output waveform quality of high performance speed regulating system is more and more high, which makes the research of special harmonic elimination PWM / SHEPWM technology become the research hotspot in the field of AC speed regulation. The special harmonic elimination technique can realize the selective elimination of harmonics and control the fundamental component of the output waveform. Because the mathematical model of SHEPWM technique is a set of nonlinear equations, the Newton iteration method and the homotopy algorithm for solving the nonlinear equations are derived in this paper. It is found that different initial values have great influence on the convergence rate of Newton iterative formula, but have little effect on the convergence rate of homotopy algorithm, but the computation time of homotopy algorithm is longer, the overall convergence rate is slower and the iteration accuracy is very low. Then, in view of the fact that different initial values have great influence on the convergence rate of solving nonlinear equations by Newton iterative method, a further study is made on the initial value of numerical solution of nonlinear equations, and the empirical formula method is used to solve the problem. The triangular carrier comparison method and the barycenter method are used to calculate the initial value sequence under the same conditions, and the calculated initial value sequence is applied to the Newton iteration method to solve the nonlinear equations. The results show that the initial value sequence calculated by the gravity center coincidence method can make the iterative convergence better. Finally, the simulation model of diode clamped SPWM and SHEPWM three-level inverter is built based on MATLAB. In the SHEPWM harmonic elimination algorithm, the initial value sequence of Newton's iterative formula is calculated by using the center of gravity coincidence method, and the nonlinear equations are solved. The numerical solution is used as the control pulse sequence of SHEPWM. The simulation results show that the harmonic content of the output waveform under the control of the SPWM method is lower than that of the output harmonic under the control of the SPWM method, that is, in the same main circuit, the input voltage is the same. The switching frequency and load condition of SHEPWM are superior to SPWM in harmonic suppression.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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