A high efficiency, low maintenance single stage or multi-stage centrifugal compressor assembly for large cooling installations. The assembly is highly efficient by virtue of a variable frequency drive (VFD) that drives a permanent magnet motor and matches compressor speed with compressor load, a direct drive impeller that eliminates gearing losses, and magnetic bearings that reduce frictional losses. The back-emf produced by the motor provides an intermediate power source for the magnetic bearings in the event of a loss of electrical power. A cooling system provides direct cooling of the rotor with gas refrigerant, and cooling of the stator with liquid refrigerant. Modular construction allows the compressor to be retrofit with upgrades. An inlet guide vane system operates without need for oil lubrication. The use of light metal castings and elimination of gearing reduces the weight to one-third or less of comparably powered conventional units.

High capacity chiller compressor

A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly comprising a flow conditioning nose, a plurality of inlet guide vanes and a flow conditioning body that positions inlet guide vanes to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning

Centrifugal compressor assembly and method

A system and method for a compressor may include an inverter drive connected to the compressor that receives electric power and modulates a speed of the compressor by modulating a frequency of the electric power. A control module connected to the inverter drive monitors compressor power data and compressor speed data from the inverter drive, and calculates a saturated condenser temperature of a refrigeration system associated with the compressor based on the compressor power data and the compressor speed data.

Variable speed compressor protection system and method

A system and method for calibrating parameters for a refrigeration system having a variable speed compressor is provided. A compressor is connected to a condenser and an evaporator. A condenser sensor outputs a condenser signal corresponding to at least one of a sensed condenser pressure and a sensed condenser temperature. An inverter drive modulates a frequency of electric power delivered to the compressor to modulate a speed of the compressor. A control module is connected to the inverter drive and determines a measured condenser temperature based on the condenser signal, monitors electric power data and compressor speed data from the inverter drive, calculates a derived condenser temperature based on the electric power data, the compressor speed data, and compressor map data for the compressor, compares the measured condenser temperature with the derived condenser temperature, and updates the compressor map data based on the comparison.

System and method for calculating parameters for a refrigeration system with a variable speed compressor

A system and method is provided to control and operate a compressor to have two or more discrete output capacities in response to an outdoor temperature measurement. During operation of the compressor in an air conditioning or cooling mode, the compressor has a first output capacity in response to the outdoor temperature being greater than a first temperature setpoint and the compressor has a second output capacity in response to the outdoor temperature being less than a second temperature setpoint.

System and method for compressor capacity modulation

A control system for a refrigerant cooled variable frequency drive (VFD) for a chiller includes a controller which controls an electronic expansion valve to attempt to maintain a heat sink for the variable frequency drive within its design operating range. When the controller is unable to maintain the heat sink within its design operating range, a load on the chiller is reduced, either by reducing the frequency of the variable frequency drive, or if the chiller includes a compressor with internal guide vanes, by partially closing the guide vanes. The power rating of the VFD can thus be optimized based on its heat generating components operating at a controlled condition, unlike an air-cooled device which is dependent on the ambient environment.

Electronic expansion valve control for a refrigerant cooled variable frequency drive (VFD)

A method for operating a vapor compression system having a compressor driven by a variable frequency drive, wherein the compressor feeds a refrigerant loop, wherein the refrigerant loop includes a cooling circuit for the variable frequency drive, and wherein a flow control member is positioned for controlling flow of refrigerant from the refrigerant loop to the cooling circuit including the steps of: sensing an operating temperature of the variable frequency drive; and controlling the flow control member based upon the operating temperature.

Refrigerant cooled variable frequency drive and method for using same

An improved transmission vent system for centrifugal compressors comprises a motor compartment, a transmission chamber, an impeller for moving refrigerant in a downstream direction, a guide vane located upstream of the impeller, and a vent pipe connected between the transmission chamber and an area upstream of the impeller and downstream of the guide vane. Refrigerant can be vented from transmission chamber to the area upstream of the impeller and downstream of the guide vane in order to eliminate the pressure differential between the transmission chamber and the compressor suction area upstream of the impeller during start-up.

Compressor transmission vent system

A compressor system with controlled lubricant reclaim includes a compressor circuit having a compressor, a condenser, and an evaporator connected by refrigerant flow line; a lubricant circuit for circulating lubricant to the compressor; a reclaim vaporizer adapted to heat a refrigerant-lubricant mixture from the evaporator whereby the mixture is heated and lubricant and refrigerant are separated to provide reclaimed lubricant to the lubricant circuit and reclaimed refrigerant to the compressor circuit; and a control unit adapted to control flow of the mixture from the evaporator to the reclaim vaporizer based upon temperature of the mixture from the evaporator and temperature of reclaimed lubricant leaving the reclaim evaporator. Methods are also provided.

Compressor system with controlled lubricant reclaim

A mounting bracket is configured to isolate a drive module of a compression type chiller assembly from vibrations. The mounting bracket includes a bracket plate configured to be attached to a chiller assembly component adjacent to the drive module, a mounting plate transversely attached to the bracket plate and configured to be connected to a rail extending along a bottom side of the drive module, and an isolator pad arranged generally over the mounting plate such that the pad is configured to be interposed between the mounting plate and the rail of the drive module.

Cornelius Holmes

Papers

Electronic expansion valve control for a refrigerant cooled variable frequency drive (VFD)

Refrigerant cooled variable frequency drive and method for using same

Compressor transmission vent system

Compressor system with controlled lubricant reclaim

Isolation of Unit Mounted Drive From Chiller Vibrations