三电平矢量控制变频器随机SVPWM技术

Random SVPWM technique for three-level vector control inverters

针对三电平矢量控制变频器优化PWM控制问题,提出一种能够使系统保持固定的开关频率和采样频率的随机空间矢量脉宽调制(SVPWM)方法。该方法在不改变矢量作用的伏秒平衡规律的前提下,通过随机调整各矢量在每个三角载波的上升段和下降段的时间分配来实现随机SVP-WM,且其随机效果不依赖于零矢量。另外,提出一种三重随机化M序列的设计思路,以增强SVP-WM的随机效果。实验结果表明,相比常规的SVPWM算法,该算法输出的线电压和相电流频谱在较宽的频带范围内分布更均匀,整数倍开关频率处的谐波幅值大大降低。

Aiming at the optimizing pulse width modulation （PWM） control in three-level vector control inverter, a random space vector PWM （SVPWM） method with fixed switching and sampling frequency is proposed. In this method, all vectors action time was randomly assigned between the ascent and descent stage of each triangle carrier on the basis of the unchanging voltage-second balance law, and the random effect does not rely on the zero vectors. To insure better random effect of the SVPWM, a design for maxi- mal-length shift register sequences （M-sequences） was proposed. Simulation and experiment results show the proposed scheme leads to a well-distributed spectrum of the line-to-line voltage and phase current, and smaller harmonic amplitude at the integral multiple of the switching frequency compared with the con- ventional SVPWM.