Abstract: A controller for a system having an evaporator, a condenser, and a dynamic compressor includes a processor and a memory, which stores instructions that program the processor to determine a first heat transfer fluid temperature at a first heat transfer fluid path of the evaporator, determine a first pressure at a first working fluid path based on first heat transfer fluid temperature, determine a second heat transfer fluid temperature at a second heat transfer fluid path of the condenser, determine a second pressure at a second working fluid path based on the second heat transfer fluid temperature, calculate an estimated pressure ratio of the compressor from the first and second pressures, determine a speed setpoint of the compressor based on the estimated pressure ratio, and operate the compressor at the speed setpoint to compress a working fluid until a condition is met.

Abstract: A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.

Abstract: A method includes commanding a motor coolant control valve to open at a first time to provide a supply of coolant to a motor coolant flow channel that delivers coolant to a motor of a compressor. A first detection of a coolant return temperature is received at a first time from a temperature sensor connected to a coolant return line that receives coolant from the motor coolant flow channel and returns coolant to another portion of the compressor. A second detection of the coolant return temperature from the temperature sensor is received at a second time after the first time. Based on the first detection and the second detection of the coolant return temperature, it is determined if the motor coolant control valve opened at the first time, and remedial action is taken when the motor coolant control valve is determined not to have opened at the first time.

Abstract: A controller for a system having an evaporator, a condenser, and a dynamic compressor includes a processor and a memory, which stores instructions that program the processor to determine a first heat transfer fluid temperature at a first heat transfer fluid path of the evaporator, determine a first pressure at a first working fluid path based on the first heat transfer fluid temperature, determine a second heat transfer fluid temperature at a second heat transfer fluid path of the condenser, determine a second pressure at a second working fluid path based on the second heat transfer fluid temperature, calculate a pressure ratio of the compressor from the first and second pressures, determine a speed setpoint of the compressor based on the pressure ratio, and operate the compressor at the speed setpoint to compress a working fluid until a condition is met.

Abstract: A vapor compression system includes a primary loop and a secondary loop. The primary loop includes a dynamic compressor operable to compress a refrigerant, a condenser fluidly connected to the dynamic compressor, a first expansion device fluidly connected to the condenser, and an evaporator fluidly connected to the first expansion device and the dynamic compressor. The dynamic compressor includes a housing, a shaft supported in the housing by a bearing, an impeller connected to the shaft, a motor operably connected to the shaft to drive rotation thereof, and a drive operable to control the motor. The secondary loop includes a second expansion device fluidly connected to the condenser, a heat exchanger fluidly connected to the second expansion device, the condenser, and the dynamic compressor, and a supply duct fluidly connected between the heat exchanger and the dynamic compressor to provide a flow of refrigerant to the bearing.

Abstract: A system includes a dynamic compressor and a controller. The dynamic compressor includes a motor having a driveshaft rotatably supported within the dynamic compressor and a compression mechanism connected to the driveshaft and operable to compress a working fluid upon rotation of the driveshaft. The controller is connected to the motor and includes a processor and a memory. The memory stores instructions that program the processor to operate the motor to compress the working fluid at a motor speed greater than a predicted minimum surge speed plus a control margin, determine when surge events have occurred, store, in the memory, an indication of each surge event that the processor determined to have occurred, and determine whether or not to take a protective action when the processor determines that a surge event has occurred.

Abstract: A method for determining a mass flow of a dynamic compressor that does not include a mass flow sensor while the compressor is operating to compress a working fluid includes determining, by a processor, a current operating point of the compressor. If the current operating point is the same as one in a map of a plurality of predetermined operating points stored in a memory, the mass flow of that predetermined operating point is retrieved as the mass flow of the current operating point. Otherwise, the processor calculates the mass flow at the current operating point from the mass flows of a subset of the predetermined operating points nearest the current operating point. The dynamic compressor continues to operate to compress the working fluid based at least in part on the calculated mass flow rate for the current operating point.

Abstract: A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.

Abstract: A system includes a dynamic compressor and a controller. The dynamic compressor includes a motor having a driveshaft rotatably supported within the dynamic compressor and a compression mechanism connected to the driveshaft and operable to compress a working fluid upon rotation of the driveshaft. The controller is connected to the motor and includes a processor and a memory. The memory stores instructions that program the processor to operate the motor to compress the working fluid at a motor speed greater than a predicted minimum surge speed plus a control margin, determine when surge events have occurred, store, in the memory, an indication of each surge event that the processor determined to have occurred, and determine whether or not to take a protective action when the processor determines that a surge event has occurred.

Abstract: A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.

Abstract: A vapor compression system includes a primary loop and a secondary loop. The primary loop includes a dynamic compressor operable to compress a refrigerant, a condenser fluidly connected to the dynamic compressor, a first expansion device fluidly connected to the condenser, and an evaporator fluidly connected to the first expansion device and the dynamic compressor. The dynamic compressor includes a housing, a shaft supported in the housing by a bearing, an impeller connected to the shaft, a motor operably connected to the shaft to drive rotation thereof, and a drive operable to control the motor. The secondary loop includes a second expansion device fluidly connected to the condenser, a heat exchanger fluidly connected to the second expansion device, the condenser, and the dynamic compressor, and a supply duct fluidly connected between the heat exchanger and the dynamic compressor to provide a flow of refrigerant to the bearing.

Abstract: A controller for a system having an evaporator, a condenser, and a dynamic compressor includes a processor and a memory, which stores instructions that program the processor to determine a first heat transfer fluid temperature at a first heat transfer fluid path of the evaporator, determine a first pressure at a first working fluid path based on the first heat transfer fluid temperature, determine a second heat transfer fluid temperature at a second heat transfer fluid path of the condenser, determine a second pressure at a second working fluid path based on the second heat transfer fluid temperature, calculate a pressure ratio of the compressor from the first and second pressures, determine a speed setpoint of the compressor based on the pressure ratio, and operate the compressor at the speed setpoint to compress a working fluid until a condition is met.

Abstract: A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.

Abstract: An HVAC system includes an unloading device, a centrifugal compressor, a gas foil bearing, a VFD and a controller. The controller is programmed to start the centrifugal compressor from a stopped condition by operating the unloading device to remove a load from the centrifugal compressor, accelerating the motor to a first speed above a liftoff speed of the gas foil bearing and below an operating speed of the centrifugal compressor, running the motor for a period of time, operating the unloading device to apply the load to the centrifugal compressor, and accelerating the motor to the operating speed.

Abstract: A system includes a dynamic compressor to compress a working fluid and a controller. The controller is connected to the dynamic compressor and includes a processor and a memory. The memory stores a map of predetermined operating points of the dynamic compressor, each predetermined operating point including a mass flow of the compressor at that predetermined operating point. The memory stores instructions that program the processor to operate the dynamic compressor to compress the working fluid and determine a current operating point of the compressor. The instructions program the processor to calculate the mass flow for the current operating point from the map of the plurality of predetermined operating points. The instructions further program the processor to continue to operate the dynamic compressor to compress the working fluid based at least in part on the calculated mass flow for the current operating point.

Abstract: A method for determining a mass flow of a dynamic compressor that does not include a mass flow sensor while the compressor is operating to compress a working fluid includes determining, by a processor, a current operating point of the compressor. If the current operating point is the same as one in a map of a plurality of predetermined operating points stored in a memory, the mass flow of that predetermined operating point is retrieved as the mass flow of the current operating point. Otherwise, the processor calculates the mass flow at the current operating point from the mass flows of a subset of the predetermined operating points nearest the current operating point. The dynamic compressor continues to operate to compress the working fluid based at least in part on the calculated mass flow rate for the current operating point.

Abstract: A system includes a dynamic compressor, a variable frequency drive (VFD), and a controller. The dynamic compressor includes a motor having a driveshaft rotatably supported within the dynamic compressor, and a compression mechanism connected to the driveshaft and operable to compress a working fluid upon rotation of the driveshaft. The VFD includes a sensor configured to sense a current provided to the motor. The controller is connected to the motor and includes a processor and a memory. The memory stores instructions that program the processor to operate the motor using the VFD to compress the working fluid, receive signals representing the current from the VFD to the motor, and determine when a surge event has occurred based at least in part on the received signals representing the current from the VFD to the motor.

Abstract: A cooling system for a compressor includes a coolant supply line, a coolant return line, a temperature sensor connected to the coolant return line to detect at least one of a temperature of the coolant return line and a temperature of coolant within the coolant return line, and a controller. The coolant supply line includes a coolant control valve, and is connectable to a housing of the compressor to deliver coolant to at least one of a plurality of coolant flow channels defined therein. The coolant return line is connectable to the compressor housing to receive coolant from the coolant flow channels and return coolant to a low-pressure side of the compressor. The controller is configured to control the coolant control valve based on the temperature detected by the temperature sensor to control the supply of coolant through the coolant supply line.

Abstract: A system includes a dynamic compressor, a variable frequency drive (VFD), and a controller. The dynamic compressor includes a motor having a driveshaft rotatably supported within the dynamic compressor, and a compression mechanism connected to the driveshaft and operable to compress a working fluid upon rotation of the driveshaft. The VFD includes a sensor configured to sense a current provided to the motor. The controller is connected to the motor and includes a processor and a memory. The memory stores instructions that program the processor to operate the motor using the VFD to compress the working fluid, receive signals representing the current from the VFD to the motor, and determine when a surge event has occurred based at least in part on the received signals representing the current from the VFD to the motor.

Abstract: A system includes a dynamic compressor and a controller. The dynamic compressor includes a motor having a driveshaft rotatably supported within the dynamic compressor and a compression mechanism connected to the driveshaft and operable to compress a working fluid upon rotation of the driveshaft. The controller is connected to the motor and includes a processor and a memory. The memory stores instructions that program the processor to operate the motor to compress the working fluid at a motor speed greater than a predicted minimum surge speed plus a control margin, determine when surge events have occurred, store, in the memory, an indication of each surge event that the processor determined to have occurred, and determine whether or not to take a protective action when the processor determines that a surge event has occurred.