Drive device for electric compressor

A drive device of an electric compressor that drives a compression mechanism to compress a fluid due to a rotation force of a rotor which is rotated by a rotating magnetic field generated from a stator coil of a synchronous motor, the drive device comprising:

• an inverter circuit formed of a plurality of switching elements;
• a drive unit that switches the plurality of switching elements to flow an alternating current from the inverter circuit to the stator coil based on a direct current voltage output from a direct current power source to generate the rotating magnetic field from the stator coil;
• a determination unit that, when the compression mechanism restarts after a stoppage of the compression mechanism, determines whether a pressure difference between a fluid intake side and a fluid discharge side of the compression mechanism is equal to or above a predetermined value;
• and
• a restart unit that
• sets a number of times that the switching elements are switched per unit time during an initial predetermined period when the compression mechanism begins to restart, and
• controls the drive unit such that an alternating current flows from the inverter circuit to the stator coil, the alternating current causing a rotation speed of the rotor to increase until a predetermined rotation speed when the compression mechanism restarts;
• and
• a masking unit, wherein
• the restart unit sets the number of times that the switching elements are switched per unit time to be lower when the determination unit determines that the pressure difference is equal to or above the threshold as compared to when the determination unit determines that the pressure difference is less than the threshold
• the drive device is applied to a vehicle including a vehicle device that generates operation sounds when operated,
• the masking unit performs a control of operating the vehicle device when the determination unit determines that the pressure difference is equal to or above the threshold, and
• the masking unit causes the vehicle device to generate the operation sounds when sounds are generated from the electric compressor due to a carrier frequency which is a frequency of a carrier wave when the pair of switching elements in each phase switches.

A drive device of an electric compressor that drives a compression mechanism to compress a fluid due to a rotation force of a rotor which is rotated by a rotating magnetic field generated from a stator coil of a synchronous motor, the drive device comprising:

• an inverter circuit formed of a plurality of switching elements;
• a drive unit that switches the plurality of switching elements to flow an alternating current from the inverter circuit to the stator coil based on a direct current voltage output from a direct current power source to generate the rotating magnetic field from the stator coil;
• a determination unit that, when the compression mechanism restarts after a stoppage of the compression mechanism, determines whether a pressure difference between a fluid intake side and a fluid discharge side of the compression mechanism is equal to or above a predetermined value;
• a restart unit that
• sets a number of times that the switching elements are switched per unit time during an initial predetermined period when the compression mechanism begins to restart, and
• controls the drive unit such that an alternating current flows from the inverter circuit to the stator coil, the alternating current causing a rotation speed of the rotor to increase until a predetermined rotation speed when the compression mechanism restarts;
• and
• a pressure control unit, wherein
• the restart unit sets the number of times that the switching elements are switched per unit time to be lower when the determination unit determines that the pressure difference is equal to or above the threshold as compared to when the determination unit determines that the pressure difference is less than the threshold,
• the drive device is mounted to a vehicle that includes
• the electric compressor which compresses refrigerant as the fluid,
• a first heat exchanger that dissipates heat from the refrigerant discharged from the electric compressor to vehicle cabin external air,
• a second heat exchanger that absorbs heat from vehicle cabin internal air into the refrigerant flowing from the first heat exchanger,
• a pressure reducing valve that reduces a pressure of the refrigerant flowing from a refrigerant outlet of the first heat exchanger toward a refrigerant inlet of the second heat exchanger, the pressure reducing valve forming a refrigeration cycle together with the electric compressor, the first heat exchanger, and the second heat exchanger,
• a first ventilator that causes an airflow of the vehicle cabin external air passing through the first heat exchanger, and
• a second ventilator that causes an airflow of the vehicle cabin internal air passing through the second heat exchanger, and
• the pressure control unit causes heat to exchange between the refrigerant and an airflow to reduce the pressure difference when the determination unit determines that the pressure difference is equal to or above the threshold by, prior to the restart unit controlling the drive unit, controlling at least one ventilator among the first ventilator and the second ventilator to generate the airflow which passes through a corresponding heat exchanger among the first heat exchanger and the second heat exchanger which corresponds to the at least one ventilator.