On-board fluid machine

An on-board fluid machine comprising:

• a housing configured to allow fluid to flow into the housing;
• an electric motor accommodated in the housing;
• and
• a driver that is supplied with DC power and drives the electric motor, wherein the driver includes
• a low-pass filter circuit configured to reduce common mode noise and normal mode noise that are included in the DC power, and
• an inverter circuit configured to convert the DC power, from which the common mode noise and the normal mode noise have been reduced, to AC power, wherein
• the low-pass filter circuit includes
• a common mode choke coil including a ring core and a first coil and a second coil that are wound around the ring core, and
• a capacitor electrically connected to the common mode choke coil,
• the driver further includes a damping unit located at a position where magnetic field lines produced by the common mode choke coil generate eddy current,
• the damping unit includes a first part and a second part, wherein the first part is box-shaped and includes a first opening, and the second part is box-shaped and includes a second opening, and the first part and the second part cooperate to accommodate the common mode choke coil in a state in which the first opening and the second opening are opposed to each other.