On-board electric compressor
An on-board electric compressor that comprises: a housing; a compression unit; an electric motor; and an inverter device. The inverter device comprises: an inverter circuit that converts direct current power to alternating current power; and a noise reduction unit that is provided on an input side of the inverter circuit and that reduces common mode noise and normal mode noise that are included in the direct current power. The noise reduction unit comprises: a common mode choke coil; and a smoothing capacitor that, in cooperation with the common mode choke coil, constitutes a low pass filter circuit. The common mode choke coil has: a core that has a first core part and a second core part; a first winding that is wound around the first core part; and a second winding that is wound around the second core part.
1. An on-board motor-driven compressor comprising:
a housing including a suction port through which fluid is drawn in;
a compression unit accommodated in the housing and configured to compress the fluid;
an electric motor accommodated in the housing and configured to drive the compression unit; and
an inverter device configured to drive the electric motor, wherein the inverter device includes
an inverter circuit configured to convert DC power to AC power, and
a noise reducing unit arranged at an input side of the inverter circuit and configured to reduce common mode noise and normal mode noise contained in the DC power before the DC power is input to the inverter circuit, wherein the noise reducing unit includes
a common mode choke coil including a core having a first core portion and a second core portion, a first winding wound around the first core portion, and a second winding wound around the second core portion, and
a smoothing capacitor that cooperates with the common mode choke coil to configure a low pass filter circuit, and
the inverter device further includes a damping unit configured to generate eddy current with a leakage magnetic flux generated from the common mode choke coil to lower a Q value of the low pass filter circuit, wherein the damping unit configures a magnetic path through which the leakage magnetic flux flows to increase a leakage inductance of the common mode choke coil.
2. The on-board motor-driven compressor according to claim 1 , wherein the damping unit covers at least one part of a side surface of the common mode choke coil.
3. The on-board motor-driven compressor according to claim 1 , wherein
the inverter device includes
a circuit board including a wire pattern, and
an inverter case accommodating the inverter circuit, the circuit board, and the noise reducing unit; and
the damping unit is configured by a material having a higher relative magnetic permeability than the inverter case.
4. The on-board motor-driven compressor according to claim 3 , wherein the damping unit is configured by a material having a higher electrical resistivity than the inverter case.
5. The on-board motor-driven compressor according to claim 3 , wherein
the damping unit is box-shaped and includes an opening covered by the inverter case, and
the common mode choke coil is accommodated in an accommodation compartment defined by the damping unit and the inverter case.
6. The on-board motor-driven compressor according to claim 1 , wherein the damping unit includes a shield electrically conductive metal film that covers at least one part of the common mode choke coil.
7. The on-board motor-driven compressor according to claim 1 , wherein
the inverter device includes a circuit board including a wire pattern; and
the damping unit includes
a shield electrically conductive metal case including an opening, wherein the common mode choke coil is accommodated in the shield electrically conductive metal case through the opening, and the shield electrically conductive metal case is fixed to the circuit board so as to close the opening with the circuit board, and
a shield electrically conductive metal film formed in a region at an inner side of the opening on the circuit board.
8. The on-board motor-driven compressor according to claim 1 , wherein the damping unit is made of an electrically conductive material of a ferromagnetic body.
9. The on-board motor-driven compressor according to claim 1 , wherein the low pass filter circuit has a specific Q value when a gain of the low pass filter circuit with respect to the normal mode noise having a frequency that is the same as a resonance frequency of the low pass filter circuit is a tolerable gain set based on a specification of a vehicle; and the damping unit is configured to lower the Q value of the low pass filter circuit from the specific Q value.