Research on Control of Fuel Cell Based Push-pull Forward Converter

四桥臂逆变器的作用是针对三相不平衡或非线性负载提供三相对称输出电压。逆变器中由于第四桥臂的存在，各桥臂控制之间存在一定的耦合关系，逆变器的控制变得非常复杂。鉴于多数文献只根据解耦变换矩阵给出了一种解耦方案，并未深入揭示四桥臂逆变器控制规律的本质。该文在分析第四桥臂作用和研究四桥臂逆变器控制规律基础上，提出了通过第四桥臂对负载产生的不平衡因素进行全补偿的思想。所提控制思想揭示了针对四桥臂逆变器的解耦变换矩阵的本质。在这一控制思想的基础上，该文给出了四桥臂逆变器的控制方法。所构造的控制方法简单实用，实现了四个桥臂的独立调节。针对不同的负载条件进行仿真，结果证明了控制方案的有效。 关键词：；；；

Control Strategy of Fourth Leg in Four-leg Inverter

Four-leg inverters are used to supply three-phase balanced voltages under an unbalanced/nonlinear load condition. As the fourth leg exists in the inverters, the control of the inverter is coupled and very complex. In many papers the decoupling transformation matrix is given and a decoupled control method is proposed, but the essence of the control law for four-leg inverters is not discovered. In this paper, based on analyzing the function of the fourth leg and studying the control law for four-leg inverters, a control idea based on compensating unbalanced effect completely by the fourth leg is proposed. The proposed idea discovers the essence of the decoupling transformation matrix for four-leg inverter. Based on the idea, a control method for four-leg inverters is proposed. The designed controller based on the idea of entire compensation by the fourth leg is very simple and effective, which realizes the independent modulations for four legs. The simulation study was carried out on different load conditions and the effectiveness of the controller is verified by simulation results.