Optimal switching control of AC-DC bridge converters for DC power system applications

AC-DC bridge converters are commonly used as a bulk supply source for DC distribution systems. The common approach to controlling the converter is to switch the devices in a predetermined sequence subject to a single firing-delay parameter. This paper outlines a more general approach to converter control, whereby the device switching may occur in any desired sequence subject to well-defined constraints. If the control sampling rate is high relative to the AC supply frequency, the system is well-described by a linear discrete-time model, whose input takes one of several time-dependent discrete values. Based on this approximate model, a time-optimal discrete-time controller is proposed; its operation and the associated switch selection strategy is verified in simulations.