To reduce the possibility that temperature of refrigerant discharged from a compressor of a refrigeration apparatus becomes excessively high by controlling torque of a motor built into the compressor, the compressor includes the motor having rotation thereof controlled by inverter control. An inverter controller controls torque of the motor using inverter control when operation frequency of the compressor is at least one value within a range of from 10 Hz to 40 Hz. When at least the operation frequency is within the range of from 10 Hz to 40 Hz, torque of the motor is controlled, and under a predetermined condition in which temperature of refrigerant discharged from the compressor easily becomes excessively high, a device controller controls devices provided in a refrigerant circuit such that refrigerant sucked into the compressor is placed in a wet vapor state.

A method of operating a refrigeration system includes initiating a compressor shutdown operation, determining a difference in a saturation temperature at a port of a compressor of the refrigeration system and an ambient temperature and comparing the difference in the saturation temperature and ambient temperature with a threshold. If the difference in the saturation temperature and ambient temperature is less than or equal to the threshold, a pump down operation is performed and if the difference in the saturation temperature and ambient temperature exceeds the threshold, a compressor shutdown operation is completed.

In an embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a variable speed drive (VSD) enclosure. The VSD enclosure includes a main drive line variable speed drive (VSD) configured to supply power to a motor, and an oil pump variable speed drive (VSD) configured to supply power to a pump. The pump is configured to supply oil to one or more moving parts of the HVAC&R system. Additionally or in the alternative to the oil pump VSD, the VSD enclosure includes a magnetic bearing controller and/or a magnetic bearing controller power supply. The magnetic bearing controller is configured to control magnetic bearings of the HVAC&R system.

An electronic expansion valve (EEV) controller allows a user to drive the stepper motor of EEVs. Thus, the EEVs toggle between an open position or a closed position. The EEV controller includes a housing, a portable power supply, a motor driver printed circuit board (PCB), a power switch, a directional switch, and a motor connector. The housing is used to protect and hold in place the motor driver PCB, the portable power supply, the power switch, the directional switch, and the motor connector. The portable power supply is used to provide electrical energy to the motor driver PCB and to the stepper motor of EEVs through the motor connector. The power switch allows a user to manually turn on or off the EEV controller and the stepper motor. The directional switch is used to toggle the stepper motor between a clockwise rotation or a counter-clockwise rotation.

Method for optimizing the energy consumption of a refrigeration unit, comprising: a step A: activating a driving device (14) of the compressor (13) by modulating the operating voltage Vout of the compressor (13) to an optimized value designed to activate the compressor (13) at an optimized speed determined by a thermodynamic optimization algorithm; a step B: regulating the driving device (14) which drives the AC/DC converter (17) so that the bus voltage is equal to the greater between a first threshold and a second threshold; wherein the first threshold is equal to the product of √2 by the value of the supply voltage and the second threshold is equal to the product of √2 by the value of the driving voltage; a step C: modifying the speed of each fan in order to minimize the value of an overall electrical consumption.

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.

A system for controlling a capacity of a compressor includes a motor of the compressor including a main winding connected at a connection point to an auxiliary winding and a drive configured to control a speed of the motor. The system includes a first switch configured to selectively connect the main winding to either a first line voltage or a first output of the drive, a second switch configured to selectively connect the connection point to either a second line voltage or a second output of the drive, and a third switch configured to selectively connect the auxiliary winding to either a capacitor or a third output of the drive. The system includes a solenoid valve configured to selectively either operate in a first capacity or a second capacity. The system includes a control module configured to control the drive, the first switch, the second switch, and the third switch.

The present disclosure relates to controls and related methods for mitigating liquid (e.g., compressor refrigerant, etc.) migration and/or floodback.

A motor driving device that drives a motor with an alternating-current power converted from a direct-current power supply, includes an inverter that receives a pulse-width modulation signal and supplies the alternating-current power to the motor, and an inverter control unit that generates the pulse-width modulation signal and supplies the pulse-width modulation signal to the inverter. The inverter control unit reduces the number of pulses of the pulse-width modulation signal generated during a first period within one period of a mechanical angle of the motor to be lower than the number of pulses of the pulse-width modulation signal generated during a second period within the one period of the mechanical angle of the motor. The first period is a period during which a load torque is lower than a load torque during the second period.

A system includes an electronic power converter and a controller. The electronic power converter supplies power to one or more motor drives of an HVAC system. The controller obtains a plurality of pulse width modulation (PWM) algorithms. Each PWM algorithm has an associated spectrum of frequencies. The controller further determines one or more resonance frequencies associated with the HVAC system. The controller also selects a first PWM algorithm from the plurality of PWM algorithms wherein the spectrum of frequencies of the first PWM algorithm lacks frequency peaks that overlap with the one or more resonance frequencies associated with the HVAC system. The controller further operates the electronic power converter according to the first PWM algorithm.