In an air-conditioning system, an outdoor unit and an indoor unit communicate through a relay device, including a plurality of communication ports; a plurality of communication networks having logical connection relationships with the respective communication ports; and a plurality of nodes having logical connection relationships with the respective communication networks. The plurality of nodes are each associated with one of the outdoor unit and the indoor unit. Among the plurality of nodes, a certain node is set as a first node, and another certain node different from the first node is set as a second node. The relay device executes transfer processing of transferring a communication frame from the first node to the second node, and then if the relay device does not receive a reception acknowledgment signal from the second node, limits a number of re-transmission times when the relay device re-transfers the communication frame to the second node.

A motor driving device and an air conditioner including the same are disclosed. The motor driving device includes a rectifier to rectify input AC power, a boost converter for boosting the rectified power from the rectifier, a first capacitor to store a pulsating voltage from the boost converter, a first inverter for outputting, to a compressor motor, AC power transformed using a voltage across the first capacitor, a second capacitor to store the rectified power from the rectifier, a second inverter for outputting, to a first fan motor, AC power transformed using a voltage across the second capacitor, and a voltage dropper to drop the voltage across the second capacitor, and to output the dropped voltage. In accordance with this configuration, the compressor motor and fan motor can be driven, using the same input AC power, even though the motor driving device uses a low-capacitance capacitor.

A hybrid power supply device of an air-conditioner for supplying multiple electric power sources to a DC rail of an inverter of a DC brushless motor of the air-conditioner to drive the operation of the DC brushless motor is introduced. Two power sources may be selectively fed into the inverter of the DC brushless motor to provide hybrid power sources to the air-conditioner in a low cost simply by connecting the outputs of two one-way rectifiers. In addition, a voltage boost circuit is provided to program each source as the main power source and a backup power source. With the skillful arrangement of a simple circuit, the air-conditioner achieves the hybrid power supply effect with a multiple of controllable power sources.

A chiller is provided that may include a plurality of compressors, a plurality of drives to drive the plurality of compressors, an input having a plurality of switches, to which IDs that correspond to the plurality of drives are assigned, and a controller to control the plurality of drives. When one or more of the switches is turned on, the controller may perform control to first operate a drive of the plurality of drives which corresponds to a switch having a smallest ID number, among turned-on switches. Thereby, when the plurality of switches is turned on, the plurality of compressors may be efficiently and stably driven.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

A control method, for a refrigerator, that includes driving a refrigerator compartment compressor that is configured to cool a refrigerator compartment; determining whether a temperature in the refrigerator compartment satisfies a first temperature; driving, based on the determination that a temperature in the refrigerator compartment satisfies the first temperature, a freezer compartment compressor that is configured to cool a freezer compartment; stopping the refrigerator compartment compressor; maintaining, after stopping the refrigerator compartment compressor, operation of the freezer compartment compressor; restarting the refrigerator compartment compressor; and varying a driving frequency of the refrigerator compartment compressor is disclosed.

A refrigerator, a sealed refrigerant system, and method are provided where the refrigerator includes at least a refrigerated compartment and a sealed refrigerant system including an evaporator, a compressor, a condenser, a controller, an evaporator fan, and a condenser fan. The method includes monitoring a frequency of the compressor, and identifying a fault condition in the at least one component of the refrigerant sealed system in response to the compressor frequency. The method may further comprise calculating a compressor frequency rate based upon the rate of change of the compressor frequency, wherein a fault in the condenser fan is identified if the compressor frequency rate is positive and exceeds a condenser fan fault threshold rate, and wherein a fault in the evaporator fan is identified if the compressor frequency rate is negative and exceeds an evaporator fan fault threshold rate.

A motor control device capable of executing a start mode that takes into consideration both the start performance with respect to a residual load and the life of a drive circuit is provided. A motor control device for executing a start mode in which a rotor is rotated by forced commutation control: stores a current value at the time when a stop command to a synchronous motor is issued; and decides, when a start command to the synchronous motor is issued after the issuance of the stop command, a target current value based on the stored current value in the start mode in response to the start command.

According to one embodiment, a cascade refrigeration cycle apparatus according to the present embodiment includes a high-temperature-side and a low-temperature-side refrigeration circuits, an inverter and a control section. The high-temperature-side refrigeration circuit includes a first compressor and a cascade heat exchanger. The low-temperature-side refrigeration circuit includes a second compressor and the cascade heat exchanger. The inverter connected to at least one of the compressors. The control section controls the inverter so that a set operating frequency for the first compressor is higher than a set operating frequency for the second compressor when an operation of the apparatus is started.

A mechanical refrigerator including a main body forming a storage space; a inverter compressor compressing a refrigerant; a microprocessor controlling drive of the compressor; a thermostat, which is connected to a power supply and switched on or switched off according to changes in a temperature of the storage space; a power detection circuit, which is connected to the power supply and the thermostat electrically, and configured to switch on or off the microprocessor according to a status of the thermostat; and a power circuit connected to the power supply and the microprocessor and configured to supply power for driving the compressor to the microprocessor.