5. Open-Loop Optimization Schemes

To set the optimized phase shift angles of multiple PWM carriers, many operating parameters should be taken into account. Some parameters, e.g. output filter parameters and rated switching frequency, seldom change during operation, while others, e.g. dc-link voltage, grid impedance, and output power, may change within the limited range. In addition, some parameters, e.g. the number of parallel-connected converters, change randomly. Therefore, building the optimization model according to the control objective and then solving the optimization model to obtain the proper phase shift angles of PWM carriers in the open-loop mode are important. This chapter begins with the basic principles of open-loop operation. Then, the optimization models for single-objective and multi-objectives are built. Finally, the methods for solving these models are presented following with the improved online fast calculation. The selected experimental results verified the performances of open-loop optimization schemes.