Patent ID: 11971045
Assignee: DAIKIN INDUSTRIES, LTD.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  H | IPC F  H

Claim 0:
1. A turbo compressor for compressing refrigerant, the turbo compressor being disposed in a refrigerant circuit that performs a refrigeration cycle, comprising:
an impeller;
a drive shaft;
a drive support unit through which currents in a predetermined current range flow to generate electromagnetic forces, the drive support unit being configured to rotationally drive the drive shaft by using one of the electromagnetic forces and to support a radial load of the drive shaft in a contactless manner by using another one of the electromagnetic forces,
the drive support unit including one bearingless motor and one radial magnetic bearing;
a power source that allows the currents to flow through the drive support unit; and
a controller that controls the power source,
wherein the bearingless motor includes a rotor-stator pair constituted by a rotor and a stator, and is configured to rotationally drive the drive shaft and to support the radial load of the drive shaft in the contactless manner,
wherein the bearingless motor, the radial magnetic bearing, and a pair of touch-down bearings are housed within a compartment formed within a casing, with the bearingless motor being arranged side-by-side with the radial magnetic bearing in the casing,
wherein the bearingless motor and the radial magnetic bearing are arranged in the compartment between the pair of touch-down bearings,
wherein the radial magnetic bearing includes a plurality of electromagnets and is configured to support the radial load of the drive shaft in the contactless manner, and
wherein the one radial magnetic bearing is the only radial magnetic bearing in the turbo compressor, and is arranged on only one side of the drive shaft in its axial direction as viewed from the bearingless motor,
wherein a magnetic flux generated in the drive support unit to rotationally drive the impeller and the drive shaft is represented by a driving magnetic flux BM,
wherein a magnetic flux generated in the drive support unit to support the radial load of the drive shaft is represented by a supporting magnetic flux BS,
wherein respective sizes of the rotor and the stator of the bearingless motor impose an upper limit of Bmax on a magnetic flux generated in the drive support unit by a total current flowing through the drive support unit,
wherein the controller issues motor power commands to the power source that limit a maximum value of a sum of the driving magnetic flux BM and the supporting magnetic flux BS in a predetermined operating region of the turbo compressor to (BM+BS)max,
wherein the controller issues, as one of the motor power commands, a command causing a magnetic flux represented by BMmax to be generated in the drive support unit to generate a driving torque corresponding to a maximum torque load in the predetermined operating region,
wherein the controller issues, as another one of the motor power commands, a command causing a magnetic flux represented by BSmax to be generated in the drive support unit to support a maximum radial load of the drive shaft in the predetermined operating region, and
wherein the controller issues the respective motor power commands to control the power source such that a relationship given by (BM+BS)max≤Bmax<BMmax+BSmax is satisfied in the predetermined operating region of the turbo compressor.