A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor having an impeller configured to rotate and drive a working fluid through a working fluid circuit of the HVAC system in an active operating mode. The HVAC system further includes a controller configured to, in response to receiving an input indicative of a transition to operate in an inactive operating mode, suspend the active operating mode by interrupting a supply of power to the compressor, adjust pre-rotation vanes of the compressor, a variable geometry diffuser of the compressor to a first position, or both to enable a backflow of the working fluid through the compressor for a first interval of time, and, after the first interval of time has elapsed, adjust the pre-rotation vanes, the variable geometry diffuser, or both to a second position to block the backflow of the working fluid through the compressor.

A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor having an impeller configured to rotate and drive a working fluid through a working fluid circuit of the HVAC system in an active operating mode. The HVAC system further includes a controller configured to, in response to receiving an input indicative of a transition to operate in an inactive operating mode, suspend the active operating mode by interrupting a supply of power to the compressor, adjust pre-rotation vanes of the compressor, a variable geometry diffuser of the compressor to a first position, or both to enable a backflow of the working fluid through the compressor for a first interval of time, and, after the first interval of time has elapsed, adjust the pre-rotation vanes, the variable geometry diffuser, or both to a second position to block the backflow of the working fluid through the compressor.

This disclosure relates to an axial magnetic bearing for a centrifugal refrigerant compressor, and a corresponding system and method. A centrifugal refrigerant compressor system according to an exemplary aspect of the present disclosure includes, among other things, an impeller connected to a shaft, and a magnetic bearing system supporting the shaft. The magnetic bearing system includes an axial magnetic bearing, which itself includes a first permanent magnet configured to generate a first bias flux, a second permanent magnet axially spaced-apart from the first permanent magnet and configured to generate a second bias flux, and an electromagnet. The electromagnet includes a coil arranged radially outward of the first and second permanent magnets, and the electromagnet is configured to selectively generate either a first control flux or a second control flux to apply a force to the shaft in a first axial direction or second axial direction opposite the first axial direction, respectively.

A deflector for a condenser, the condenser has an inlet communicated with exhaust pipes of a compressor, and the deflector is provided at the inlet, the deflector includes: a flow guiding structure having a first tube section and a second tube section of increasing diameter, the second tube section being positioned below the first tube section and extending into the condenser when mounted in place; and a support assembly for fixing the flow guiding structure at the inlet, at least a part of the refrigerant gas flow flows through the interior of the first tube section, and at least another part of the refrigerant gas flow flows through the outer side of the first tube section.

Chiller systems can include a controller that is configured to determine whether to restart the chiller in a rapid restart mode or a soft loading restart mode, and methods can include determining the mode for restarting the chiller. The soft loading restart mode controls the chiller to provide a comparatively gradual loading, to avoid overshooting a target temperature. The rapid restart mode more aggressively loads the chiller to return more rapidly to a particular load level. The determination of the restarting mode can be based on characteristics of the interruption of power to the chiller system. In chiller systems, the controller can receive power from an uninterruptable power source to maintain continuity of power. The logic used by the controller can be based on whether or not the controller shares continuity of power with other components of the chiller system.

This disclosure relates to refrigerant compressors, and, in particular, relates to cooling for the power electronics of such compressors. An example refrigerant system includes a main refrigerant loop in communication with a condenser, an evaporator, and a compressor. The refrigerant system further includes at least one cooling line configured to direct refrigerant from the main refrigerant loop to cool a chamber containing electronic components. A method is also disclosed.

This disclosure relates to refrigerant compressors, and, in particular, relates to cooling for the power electronics of such compressors. An example refrigerant system includes a main refrigerant loop in communication with a condenser, an evaporator, and a compressor. The refrigerant system further includes at least one cooling line configured to direct refrigerant from the main refrigerant loop to cool a chamber containing electronic components. A method is also disclosed.

A compressor according to an exemplary aspect of the present disclosure includes, among other things, a mixed compression stage having both axial and radial components arranged along a main flow path, and a radial compression stage having an impeller with a plurality of vanes arranged in the main flow path downstream of the mixed compression stage. The impeller is configured to rotate about an axis and has an outlet downstream of the vanes. A movable diffuser is arranged at the outlet, and the movable diffuser is configured to vary an area of the outlet.

A compressor according to an exemplary aspect of the present disclosure includes, among other things, a mixed compression stage having both axial and radial components arranged along a main flow path, and a radial compression stage having an impeller with a plurality of vanes arranged in the main flow path downstream of the mixed compression stage. The impeller is configured to rotate about an axis and has an outlet downstream of the vanes. A movable diffuser is arranged at the outlet, and the movable diffuser is configured to vary an area of the outlet.

The technologies described and recited herein pertain to a permanent magnet motor having multiple voltage taps so that the motor may run in multiple configurations, e.g., a low-range and a high-range, and have multiple optimal operating points.