Research On SPWM Control Technology And Open Circuit Fault Diagnosis Of Cascaded Inverters

Firstly, some control methods about traditional cascaded inverters which cell has the same input dc voltage is generally introduced in this paper. And then, this paper presents a control method about cascaded inverters utilizing different (binary relation) dc input voltage on each cell. Taking cascaded inverters with two cells for example, this paper analyzes and comprises the SPWM (Sinusoidal Pulse Width Modulation) methods, output voltage levels and harmonious characteristic of cascaded inverters utilizing same dc voltage and binary relation dc voltage. And then, based on output voltage and output filter inductor current feedback SPWM control, the cascaded inverters' prototype is made and the performance of inverter system is analyzed with the variatation of parameters while some conclusion is drawn in this paper. The simulation and experimental results illustrate advantages of the cascaded inverters utilizing binary relation dc voltage and the control method presented in this paper, such as more output voltage levels, less harmonious content, and when one inverter cell is fault, the control method can make cascaded inverters still output voltage which corresponds with requirements. Finally, the diagnoses of cascaded inverters which have a switch's open circuit fault is researched, and a diagnoses method is presented in this paper. The simulation results demonstrate that the method is simple and correct, which lays the foundation for farther researching the redundancy of cascaded inverters.