控制网络延时对SPWM逆变器输出电压的影响

Influence of Control Network Delay on Output Voltage of SPWM Inverter

针对中大容量变流器分布式控制系统存在固有的控制网络延时，详细推导了SPWM逆变器系统在单桥臂延时和桥臂串行延时的情况下输出线电压的数学表达式，并对两种情况下的输出线电压进行了详细地仿真定量分析和实验验证，仿真和实验结果与理论分析基本吻合，仿真和实验结果表明控制网络延时的引入使得系统输出线电压中出现了开关频率（弧）的奇数倍高次谐波，同时边频带中出现了基波频率（CO，）的3倍数次谐波，系统输出线电压总谐波系数（THD）值和各主要次谐波幅值随着控制网络延时的增加而发生变化，且THD值在单桥臂网络延时50％开关周期和桥臂串行网络延时为50％～100％开关周期时达到最大值。

Considering the control network delay inherent in the medium-large capacity inverter system, this paper derives the mathematical expression for the output line-to-line voltage of the SPWM inverter system under the conditions of the single-leg delay and the legs＇ serial delay, and makes a detailed quantitative analysis and experiment verification of the output line-to-line voltage in the both cases through simulation, The results of the simulation and experiment are basically consistent to the theoretical calculation. The results shows the higher harmonic with an odd multiple of the switching frequency （cos） and the sub-harmonics with a three multiple of the fundamental frequency （O）1） in sideband appearing due to the introduction of the control network delay. The total harmonic distortion factor（THD） value of the system＇s output line-to-line voltage and the amplitude value of main sub-harmonics vary according to the increasing control network delay. The value of the THD are the maximum when the single-leg network delay is 50% of switching period or the legs＇ serial network delay is 50%-100% of switching period.