The ornamental design for a wireless powertransferdevice, as shown and described.
1. Wireless power transfer device
1.1 : Front perspective view
1.2 : Back perspective view
1.3 : Front
1.4 : Back
1.5 : Top
1.6 : Bottom
1.7 : Left
1.8 : Right
Design 1: this article is a wireless power transfer device for charging batteries of electric movable bodies, such as a vehicle or a vessel, from outside; this article can be used as a wireless power transfer device on both the power transmitting side and power receiving side; two nearly hexagonal cylindrical parts on the back side of this article are connector parts; thin lines drawn on the surfaces of this article are shading lines identifying the shapes of the three-dimensional surfaces.