The ornamental design for an inverterpowersupply, as shown and described.
FIG. 1 is a first perspective view of an inverter power supply showing my design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines shown in the drawings depict portions of the inverter power supply in which the design is embodied that form no part of the claimed design.