Low-noise transformation device

The invention discloses a low-noise type voltage transformation device which comprises a centrifugal fan, the centrifugal fan comprises a shell and a fan wheel, the shell comprises a lower bottom plate (1), a side plate (2) and an upper cover plate (3), the fan wheel comprises a hub (4) and fan blades (5), the upper cover plate is provided with a first air inlet (6), the lower bottom plate is provided with a second air inlet (7), and a plurality of supporting ribs (8) are arranged in the second air inlet. The fan is characterized in that a plurality of flow guide grooves (11) are formed in the upper surface of the lower bottom plate (1), the flow guide grooves are evenly distributed in the circumferential direction, and the upper surface of the lower bottom plate (1) is adjacent to the fan blades. The multiple flow guide grooves are formed in the upper surface of the lower bottom plate and evenly distributed in the circumferential direction, the inlet noise of the second air inlet can be effectively lowered,