一种混合9电平电压源逆变器及其变频脉宽调制

介绍了一种应用于中高压变频调速装置的9电平输出电压源逆变器，逆变器的主电路由2种不同拓扑结构的逆变电路组成，分别使用不同参数的开关器件实现，可以综合利用阻断电压高的器件和开关速度快的器件的优点。分析了逆变器主电路的拓扑结构及特点，研究了主电路的开关模式后提出了一种基于载波调制的适合于任意电平数目混合逆变器的PWM(脉宽调制)算法，最后仿真研究了混合9电平逆变器在变速驱动场合中的应用，并验证了算法的有效性。对线电压的频谱分析表明，混合9电平逆变器有很好的输出波形，输出谐波含量少，在高频段输出线电压的总谐波畸变率小于5％，输出电压的dv／dt小，可用于驱动大容量的中高压异步电动机。

A HYBRID 9-LEVEL VOLTAGE SOURCE INVERTER AND PWM STRATEGY

This paper introduces a novel inverter topology that can be used for medium voltage inverters to realize the application of adjustable speed drive. This is a voltage source inverter with 9-level voltage output. The inverter is composed of two different topological circuits, implemented by switching devices with two kinds of different parameter, combining the advantages of the devices capability of high blocking voltage and high switching speed. The paper analyzes the feature of inverter circuit topology, studies the switching pattern of this inverter and presents a hybrid PWM method based on carrier-based modulation, which is available to any-level hybrid inverters. The simulation result demonstrates the availability of the hybrid 9-level voltage source inverter applied to ASD and the validity of the hybrid PWM method. Fourier spectrum of line-to-line voltage indicates that hybrid 9-level inverter has a better spectral performance of output voltage waveform, less harmonics content and dv/dt, and the total harmonics distortion of output line voltage in the high frequency region is less than 5% . The hybrid 9-level inverter can be used to drive the medium-voltage high power asynchronous motors.