三相四桥臂逆变器控制技术研究

摘要

三相四桥臂逆变器可以解决不平衡负载引起输出电压不平衡的问题.采用开环控制或传统同步旋转坐标系PI控制时,三相四桥臂逆变器输出电压仍存在不平衡现象.为了揭示其原因,首先建立了三相四桥臂逆变器数学模型,在此基础上分析了三相四桥臂逆变器输出电压不平衡的根本原因,并提出相应的解决方案.该方案有效地抑制了不平衡负载电流扰动对输出电压的影响,保证了三相四桥臂逆变器在不平衡负载情况下输出三相对称正弦电压.最后在Matlab/Simulink环境下对空载、平衡负载、不平衡负载三种情况下系统开环和闭环控制进行了仿真研究,仿真结果验证了该解决方案的正确性.%Three-phase four-leg inverter has the capability of rejecting the unbalanced voltage due to asymmetrical loads. However, the unbalanced voltage still exists when the open-loop control or synchronous frame PI controller are used for three-phase four-leg inverter. In order to explain the reason for this phenomenon, the mathematical model for three-phase four-leg inverter is built, based on which the unbalanced output voltage problem is discussed. And then the solution to the voltage unbalance problem is presented. The proposed solution can mitigate the effect of unbalanced load current on three-phase output voltages, so the balanced sinusoidal voltage regulation can be achieved under the unbalanced loads. Finally, the system open-loop control and closed-loop control simulations are carried out under the conditions of no-load, balanced load and unbalanced load in Matlab/Simulink. Simulation results prove that the presented solution is valid.This work is supported by National Natural Science Foundation of China (No. 50837003 and No. 50977081) and Natural Science Foundation of Hebei Province (No. E2010001261).