The present disclosure provides an air conditioner including a compressor and a drive circuit configured to drive the compressor. The drive circuit includes an AC path, a rectifier connected to the AC path, a DC path on an output side of the rectifier, a smoothing capacitor connected to the DC path, an inverter connected to the DC path, a switch disposed on an electric path from the AC path to the smoothing capacitor, and a controller configured to close and open the switch during a preheating operation of supplying electricity for preheating the compressor via the inverter.

A compressor includes a casing that stores lubricating oil in a bottom of the casing, a compression mechanism housed in the casing, a housing that supports the compression mechanism and forms a crank chamber, a first oil return passage arranged to guide the lubricating oil flowing into the crank chamber downward, and a second oil return passage. The first oil return passage is provided with an oil return guide that contracts a flow of the lubricating oil. An upper portion of the casing forms an oil separation space that separates the lubricating oil from a high-pressure refrigerant discharged from the compression mechanism in the oil separation space. The second oil return passage guides the lubricating oil separated in the oil separation space downward, and an outlet of the second oil return passage is disposed near an outlet of the oil return guide.

An expander and motor-compressor unit is disclosed. The unit includes a casing and an electric motor arranged in the casing. A compressor is arranged in the casing and drivingly coupled to the electric motor through a central shaft. Furthermore, a turbo-expander is arranged for rotation in the casing and is drivingly coupled to the electric motor and to the compressor through the central shaft.

A compressor assembly includes a compressor motor having a main winding coupled with a line terminal to receive power from a line voltage source, and an auxiliary winding. The assembly includes first and second capacitors each coupled between the line terminal and the auxiliary winding, a first relay to selectively couple the first capacitor and the second capacitor in parallel, a second relay coupled to selectively inhibit the supply of power from the line voltage source to the auxiliary winding via the first capacitor, and a control circuit configured to close the first relay in response detection of excess load condition criteria, and to subsequently open the first relay in response to detection of normal load condition criteria. The excess load condition criteria and the normal load condition criteria each include at least one of a voltage of the main winding and a voltage of the auxiliary winding.

A compressor has: a motor that has a stator provided around an axis of a rotor; a rotating shaft that is fixed to the rotor; a bearing that supports the rotating shaft; an impeller that is connected to the rotating shaft and compresses fluid; and a casing that accommodates the motor. In this compressor, the stator has: a coil that encircles the axis of the rotor; and a stator core that has a magnetic pole facing, in a radial direction of the rotor, an outer circumferential surface of the rotor, via a gap.

A turbo compressor and a refrigeration cycle device having a turbo compressor are provided. The turbo compressor includes a housing having a motor chamber; a drive motor having a stator and a rotor in the motor chamber of the housing; a first compression portion and a second compression portion, respectively, provided on opposite ends of a rotary shaft; a connecting passage that connects an exit of the first compression portion and an entrance of the second compression portion; an inlet passage that penetrates a first side of the housing to communicate with an inside of the motor chamber and guide a refrigeration fluid to the motor chamber; and an outlet passage that penetrates a second side of the housing to communicate with the inside of the motor chamber and guide the refrigeration fluid in the motor chamber out of the housing. Thus, a gas foil bearing provided in the motor chamber may be quickly actuated by supplying the refrigeration fluid to the motor chamber, and at a same time, heat generated from the motor chamber may be quickly dissipated even in a highspeed operation, thereby improving efficiency of the turbo compressor and a refrigeration cycle device having a turbo compressor.

A damping unit includes a damping bent portion having the form of a flat plate and bent from a damping side portion. The damping bent portion is thermally coupled to a heat dissipation surface. This transfers the heat generated by the damping unit from the damping bent portion, in addition to the damping side portion, to the heat dissipation surface of an inverter case.

An electric compressor is provided in which the connection strength between lead terminals from a motor and an inverter circuit section is improved. The electric compressor 1 is constituted by electrically connecting lead terminals 24 to 26 of a motor and an inverter circuit section 3 for supplying power to the motor by a motor side connection terminal 28. The inverter circuit section 3 is protrusively provided with terminal connection portions 19 to 21 each having a screw groove portion. The motor side connection terminal 28 has a flat plate terminal portion. The flat plate terminal portion is fixed to the inverter circuit section 3 by a nut 91 screwed into each of the screw groove portions of the terminal connection portions 19 to 21 and electrically connected to the inverter circuit section 3 in that state.

A method of operating a heat exchanger system in which a compressor, which is drivable by a motor, is fluidly interposed between an evaporator and a condenser following receipt of a shutdown command is provided. The method includes positioning inlet guide vanes (IGVs) of the compressor in a first position in the event of at least one of a first precondition being in effect and the first and a second precondition both not being in effect. The method further includes positioning the IGVs in a second position in an event the first precondition is not in effect but the second precondition is in effect, ramping a speed of the compressor down until a third precondition takes effect, removing power from the motor and positioning the IGVs in the first position once power is removed from the motor.

A rotor includes a rotation shaft, a rotor core, and a permanent magnet. The rotor core includes a shaft fixing part having a shaft insertion hole in which the rotation shaft is inserted, an annular magnet holding part surrounding the shaft fixing part from outside in a radial direction about a central axis of the rotation shaft and being distanced from the shaft fixing part, and a connecting part connecting the shaft fixing part and the magnet holding part to each other. The permanent magnet is mounted in the magnet holding part and forms a first magnetic pole. A portion of the magnet holding part adjacent to the permanent magnet in a circumferential direction forms a second magnetic pole. The connecting part has at least two ribs distanced from each other in the direction of the central axis.