A refrigeration cycle apparatus includes a plurality of outdoor units. Each of the plurality of outdoor units includes an outdoor heat exchanger, a compressor, and a sensor to detect the quantity of refrigeration oil in the outdoor unit. A controller has a first operation mode in which a part of the plurality of outdoor units is operated and another outdoor unit is stopped; and a second operation mode in which all of the plurality of outdoor units are operated. In the first operation mode, when the operating time of an operating outdoor unit exceeds a prescribed time and the quantity of refrigeration oil in the compressor of the operating outdoor unit is equal to or larger than a prescribed quantity, the controller stops the operating outdoor unit and makes a switch to bring a stopped outdoor unit of the plurality of outdoor units into operation.

A heating system having a plurality of outdoor air source heat pumps. An indoor heat transfer system receives heat from the plurality of outdoor air source heat pumps, and uses the heat for a heating application. The heating system is configured to control the plurality of outdoor air source heat pumps so as to reduce an occurrence of the plurality of outdoor air source heat pumps simultaneously being in a defrost cycle. Water to water heat pump(s) are provided in a cascade configuration with the indoor units to produce higher temperature water for the heating application.

A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a first portion of a refrigeration system within a building; and an isolation module configured to selectively open and close an isolation valve of the refrigeration system and to, via the isolation valve, maintain the amount of refrigerant within the first portion within the building below a predetermined amount of the refrigerant.

A refrigerant control system includes: a charge module configured to determine an amount of refrigerant that is present within a refrigeration system of a building; a leak module configured to diagnose that a leak is present in the refrigeration system based on the amount of refrigerant; and at least one module configured to take at least one remedial action in response to the diagnosis that the leak is present in the refrigeration system.

A method for adjusting compression efficiency for an HVACR system having a variable-frequency drive (VFD) is disclosed. The method includes determining a first compression efficiency, determining an operating point, determining a region of an operating map when a difference between the operating point and a previously determined operating point exceeds a predetermined threshold, adjusting a VFD input to a first input based on the region of the operating map, and controlling the VFD using the first input for a predetermined period of time. The method also includes determining a second compression efficiency and an operation restriction, adjusting the VFD input to a second input based on the operation restriction and a difference between the first compression efficiency and the second compression efficiency, and controlling the VFD using the second input. The method also includes utilizing machine learning control techniques to control several system variables to optimize the compression efficiency.

An expansion valve control method for a multi-split air-conditioning system to solve the problem of detecting leakage of an expansion valve of a multi-split air-conditioning system. The system includes an outdoor unit and a plurality of indoor units connected to the outdoor unit, each of the indoor units is connected to the outdoor unit by a first pipeline and a second pipeline. The expansion valve control method includes acquiring an indoor temperature of an environment where an indoor unit is located; acquiring the temperature of a first pipeline of the indoor unit and the temperature of a second pipeline of the indoor unit when the indoor unit is in a shutdown state; and according to at least the indoor temperature of the environment where the indoor unit is located, determining the leakage condition of an expansion valve of the indoor unit.

A method for adjusting compression efficiency for an HVACR system having a variable-frequency drive (VFD) is disclosed. The method includes determining a first compression efficiency, determining an operating point, determining a region of an operating map when a difference between the operating point and a previously determined operating point exceeds a predetermined threshold, adjusting a VFD input to a first input based on the region of the operating map, and controlling the VFD using the first input for a predetermined period of time. The method also includes determining a second compression efficiency and an operation restriction, adjusting the VFD input to a second input based on the operation restriction and a difference between the first compression efficiency and the second compression efficiency, and controlling the VFD using the second input. The method also includes utilizing machine learning control techniques to control several system variables to optimize the compression efficiency.

In order to reduce the effect on a compressor caused by foaming in an oil tank, a control unit for controlling an oil pump starts the oil pump before a compressor is started (SA1), starts the compressor (SA4) when an oil supply differential pressure P satisfies a compressor startup condition during a reference time Tas from the starting of the oil pump (“Yes” in SA3), and extends the operation of the oil pump for a prescribed time without starting the compressor (Step SA5) when the compressor startup condition is not satisfied (“No” in SA3).

Provided is an air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, and a controller configured to control the heating means. The controller includes a heat load learning unit configured to learn a heat load based on temperature data and air conditioning data, a stagnation prevention control start timing estimation unit configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and a device control unit configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.

An HVAC system includes a pressure sensor is disposed in a suction line between a compressor and an indoor heat-exchange coil. The pressure sensor is electrically coupled to a compressor controller. An HVAC controller is electrically coupled to the compressor controller. The HVAC controller is configured to transmit a signal to the compressor controller to activate and de-activate the compressor. The compressor controller is configured to receive a signal from the HVAC controller to activate the compressor, determine a start speed of the compressor, monitor a run time of the compressor, and modulate a speed of the compressor.