Patent ID: 8350518

Claim:
A control apparatus for a series-connected multi-level matrix converter, comprising: each voltage commanding device provided for each of single-phase matrix converters to generate a voltage reference to each of the single-phase matrix converters, from an output phase voltage reference for an output phase voltage of the series-connected multi-level matrix converter, the series-connected multi-level matrix converter including the single-phase matrix converters whose outputs are serially connected and which are connected to a plurality of secondary windings of a transformer and constructing output phases, the single-phase matrix converters each including a main circuit having a bidirectional switching element, a snubber circuit connected to an input and an output of the main circuit to suppress a surge voltage, and a DC voltage detecting section configured to detect a DC voltage of the snubber circuit to output a DC voltage detection value, the transformer having a primary winding connected to a three-phase AC power source and the plurality of secondary windings; a DC over-voltage detector configured to output a DC over-voltage signal when the DC voltage detection value exceeds a set voltage value which is preliminarily set; and a voltage modifying device, when the DC over-voltage signal is outputted, configured to decrease the voltage reference to a corresponding single-phase matrix converter among the single-phase matrix converters based on a deviation between the DC voltage detection value and the set voltage value.