A refrigeration and air-conditioning apparatus rapidly varies the pressure or the temperature inside a liquid reserve container to identify a liquid level position inside the liquid reserve container on the basis of the surface temperature of the liquid reserve container.

An inverter controller, a method of operating a controller and a field-installable kit. In one embodiment, the controller includes: (1) a thermostat interface configured to receive conventional thermostat signals providing for a ventilation mode, first- and second-stage cooling modes and at least one heating mode and provide relay control signals for an inverter forward start relay, first- and second-stage cooling speed select relays and at least one heating relay and (2) an inverter controller coupled to the thermostat interface and configured to receive the relay control signals and provide an inverter forward start signal, an inverter high speed set, an inverter medium speed set and an inverter ventilation speed set.

A compressor control apparatus, and a refrigerator including the same are provided. The operation of two compressors may be controlled using an alternating current (AC) switch, thereby minimizing a number of components, as well as increasing compressor capacity and enhancing operation efficiency. A plurality of operation modes may be used to correspond to a load or freezing capacity using two compressors, and the two compressors may be operated in a separate or simultaneous manner using a drive including two (AC) switches, thereby simplifying the configuration of the system.

A direct-current power supply device is a direct-current power supply device that converts a three-phase alternating current to a direct current and supplies the direct current to a load, and includes a first capacitor and a second capacitor connected in series between output terminals to the load, a charge unit that selectively charges one or both of the first capacitor and the second capacitor, and a control unit that controls the charge unit. The control unit controls an output voltage of the direct-current power supply device by a charging period of the charge unit, and also controls a power factor and a harmonic current of the direct-current power supply device by a charge timing with respect to a reference phase of the three-phase alternating current of the charge unit as a reference.

Disclosed are a compressor applied to a refrigerator not having a cycle matching function or a refrigerator not including a controller, and capable of controlling a driving of a linear motor by the compressor itself, and a method for controlling the same. The compressor installed at an apparatus including a refrigeration cycle includes: a piston which reciprocates in a cylinder; a linear motor configured to provide a driving force to move the piston; a sensor configured to sense a motor current of the linear motor; and a compressor controller configured to detect information related to a load of the apparatus, in a separated manner from a controller which controls a body of the apparatus, wherein the compressor controller calculates a phase difference between a stroke of the piston and the sensed motor current, and wherein the compressor controller controls a driving of the linear motor in correspondence to the detected load, such that the calculated phase difference is within a range of a reference phase difference.

An electric motor system is described. The electric motor system includes a drive circuit including an inverter configured to supply variable frequency current and a contactor configured to supply line frequency current. The electric motor system also includes an electric motor coupled to the drive circuit wherein the electric motor is communicatively coupled to a controller. The controller is configured to control the inverter to supply variable frequency current to the electric motor, thereby operating the electric motor at a motor speed, and determine, based upon at least one input parameter, a maximum potential motor speed the inverter can achieve. The controller is also configured to receive a command to operate the electric motor at line frequency current and control the drive circuit to transition from supplying variable frequency current to supplying line frequency current before the maximum potential motor speed the inverter can achieve is reached.

In order to improve a method for selecting a frequency converter for a refrigerant compressor unit comprising a refrigerant compressor and an electric drive motor in such a way that the frequency converter is optimised for the application in question, it is proposed that a working state suitable for the operation of the refrigerant compressor unit is selected in an application field of an application diagram of the refrigerant compressor, that an operating frequency is selected for this selected working state, and that, on the basis of drive data, a working state operating current value corresponding to the selected working state and the selected operating frequency is ascertained for the operation of the refrigerant compressor unit.

A method controls a refrigerator. The refrigerator includes a compressor that includes a piston and uses refrigerant as lubricant for the piston, and the method includes determining an end time point of a refrigerant recovery operation based on a driving input value of the compressor to thereby reducer abrasion of the piston and power consumption.

The present invention relates to a motor driving apparatus and a refrigerator including the same. A motor driving apparatus according to an embodiment of the present invention comprises: a signal delay unit for delaying an input speed order signal; an inverter control unit for outputting an inverter switching control signal, on the basis of the speed order signal delayed by the signal delay unit; and an inverter for converting an input operation direct current power into a predetermined alternating current power, on the basis of a switching operation according to the inverter switching control signal, and driving a motor using the converted alternating current power. Therefore, it is possible to prevent starting failure and reduce noise.

An electric motor drive device including a drive controller configured to control an operation of an inverter, the drive controller including a frequency setting unit configured to set an operating frequency of an electric motor, a frequency determining unit configured to determine whether or not the operating frequency set in the frequency setting unit is equal to or lower than a set frequency threshold value, a voltage determining unit configured to determine whether or not a value of a DC voltage is equal to or larger than a set voltage threshold value, and an inverter controller configured to control the inverter based on the operating frequency set in the frequency setting unit.