A method for operating a linear compressor of an appliance, such as a refrigerator appliance, is provided. In one example implementation, the method can include operating a motor of the linear compressor in order to drive a rotor of the motor. The method can further include obtaining, via a controller of the linear compressor, one or more feedback measurements of one or more electrical characteristics of the motor. The method can further include controlling, based at least in part on the one or more feedback measurements, the motor of the linear compressor using a single-phase vector-like control scheme.

A refrigerator is provided. The refrigerator includes a storage compartment, an evaporator, a compressor, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a voltage control circuit configured to adjust an input voltage of the RF power supply, a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode, memory storing instructions, and at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory, wherein the instructions, when executed by the at least one processor individually or collectively, cause the refrigerator to operate the compressor, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current, and adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food.

An electric motor drive device includes: a three-phase diode bridge which rectifies and converts a three-phase AC voltage into a DC voltage; an electrolytic capacitor which smooths a DC voltage; a DC reactor provided between the three-phase diode bridge and the electrolytic capacitor; an inverter which converts a DC voltage smoothed by the electrolytic capacitor into an AC voltage and outputs the AC voltage to a motor; a voltage detecting unit which detects a DC voltage output from the three-phase diode bridge; and an inverter control unit which detects an imbalanced state of the three-phase AC voltage on the basis of a DC voltage value which is a detection value of the DC voltage obtained by the voltage detecting unit, and controls the inverter on the basis of a detection result of the imbalanced state.

A method for controlling a compressor system includes an electrically operated compressor for compressing a working medium, and a further electrical load. The compressor includes an electric motor for compressing the working medium, an inverter supplying the electric motor with single- or multi-phase alternating current, a power factor correction filter (PFC) supplying the inverter with direct current and whose current input for supplying power to the compressor connects to a grid current source providing alternating current. For supplying power thereto the further electrical load connects to the same grid connection point as the power factor correction filter. The method includes operating the compressor system with electrical current from the grid current source, determining at least one current characteristic value of the further load, and controlling the power factor correction filter of the compressor at least in dependence of the determined at least one current characteristic value of the further load.

A cryogenic refrigeration system and method are disclosed. The cryogenic refrigeration system comprises: a refrigerator unit comprising an expansion unit and a variable speed compressor configured to compress refrigerant. The variable speed compressor is configured to receive refrigerant from the refrigerator unit via a lower pressure line and to supply compressed refrigerant to the refrigerator unit via a higher pressure line. There is also control circuitry configured to control the variable speed compressor to maintain a power consumption of the variable speed compressor below a predetermined threshold value, by during cooldown controlling the compressor to initially operate at a reduced frequency and later increasing a frequency of operation of the variable speed compressor such that the variable speed compressor operates at a higher frequency.

A refrigeration system and a method of operating the same is described. The refrigeration system includes: an induction motor having a rotor; an electrical power source connected to the induction motor, wherein rotation of the rotor powers a load of the refrigeration system; and a controller. The controller is configured to: identify a predetermined threshold value of a parameter of the induction motor and a predetermined relationship associated with the induction motor between the parameter and a derating amount; determine the parameter of the rotor during rotation of the rotor; determine whether the determined parameter meets a first condition; upon determining that the first condition has been met, determine a derating amount based on the determined parameter and the predetermined relationship; and derate the one or more loads by the derating amount.