Cascade frequency converter

A cascade frequency converter comprises a plurality of power units, an isolation switch module and a frame structure, the frame structure is provided with two or more layers of supporting tables capable of containing the power units and insulation supporting columns for supporting the supporting tables, and the isolation switch module is placed at the left end or the right end of the first layer of supporting table. The power units are sequentially placed at other positions of the supporting table, and the power units are connected in series and then connected to the isolation switch module. The cascaded frequency converter adopts a two-layer or more than two-layer frame structure, and a plurality of power units can be simultaneously placed on each layer of supporting platform, so that the cascaded frequency converter can be used for placing more power units, is compact in structure and high in space utilization rate, saves the space of a machine room and land resources, and is suitable for popularization and