Optimal-sequence-based control of switching power converters in interactive power networks

We develop and demonstrate an optimal switching- sequence-based control (OSBC) scheme for switching power converters (SPCs) that guarantees global stability and also meets predefined performance criteria. First, using techniques based on composite Lyapunov functions (CLFs) and piecewise-linear (PWL) models of the SPC, we determine the set of switching sequences that guarantee global stability. Next, by solving optimization problems using predefined cost functions for the saturated (transient) and unsaturated (steady-state) regions of operation, we determine the optimal switching sequence and the duration of time spent in it. Further, we investigate how the proposed OSBC can be applied to SPCs in interactive power networks (IPNs). For such a system, the periodically-varying network feedbacks are estimated and the OSBC is modified to account for such disturbances. The application of the proposed OSBC is demonstrated using a parallel-connected network of three- phase voltage-source inverters (VSIs).